Catheterization and Cardiovascular Diagnosis 27:234-242 (1992)
Long-Tip Guiding Catheter: Successful and Safe for Left Coronary Artery Angioplasty Jan Voda, MD A long-tip guiding catheter was designed for angioplasty of the left coronary artery. Principal factors of guiding catheter function were identified, and the catheter’s shape was designed to utilize them efficiently. Emphasis was placed on an overbent secondary curve (150-180’) for more precise catheter control. The distal tip of the catheter is 2 cm long in the 4.0 size and the 20%. A 1.5 cm long segment beprimary bend is shallow, tween the secondary and tertiary curves enhances stability and support. Catheter performance was studied during procedures on 90 patients; 89 patients underwent coronary artery angioplasty and one patient underwent diagnostic angiography. The success rate for angioplasty was 95% with no major complications, Mild pressure damping occurred in 18 patients, and mild catheter displacement from the left main coronary artery occurred in 24 patients. Catheter support was judged as excellent to very good in 82 patients. Judkins or Amplatz catheters were not required during this study. The observed disadvantages of the long-tip catheter were the risk of catheter buckling up during advancement into the left main coronary artery and, perhaps, a higher risk of pressure damping. Superselective engagement of the catheter in the left anterior descending or circumflex arteries may be a problem when the left main coronary artery is very short. This study showed the long-tip catheter to be safe and highly successful for angioplasty of the left coronary artery. o 1992 wiiey-Liss, 111c.
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Key words: guiding coronary artery
catheter,
coronary angioplasty,
left
INTRODUCTION
Today’s guiding catheters for angioplasty of the left coronary artery originated from diagnostic catheters, and they have been used with considerable success and safety for many years. Essentially unchanged shapes of Judkins and Amplatz [ 1.21 diagnostic catheters are still most frequently used; however, the role of guiding catheters is fundamentally different from that of diagnostic catheters. Therefore, it is not surprising that in many cases the performance of these guiding catheters is not adequate. In terms of functional differences between Judkins and Amplatz catheters, currently used diagnostic and guiding catheters can be classified into two groups-those with distal curves that are overbent or underbent prior to their insertion into the circulation. Importantly, the catheters have “memory,” which could be defined as a tendency to keep or resume original configuration. The memory is an additional useful factor in manipulation of the catheters and plays a major role in engagement of the Judkins, 0 1992 Wiley-Liss, Inc.
long-tip, or Amplatz catheters into the left main coronary artery (Fig. 1). There are important differences in response and manipulation of the overbent and underbent catheters. Inherently, the overbent catheters have good and predictable response, whereas underbent catheters may be difficult to manipulate. This is the principal reason why the Judkins catheter is the most popular in diagnostic studies and as a guiding catheter in angioplasties. This is also the main reason why we selected the overbent principle for design of the long-tip catheter. THEORETICAL ANALYSIS
An important function of guiding catheters is support of devices such as balloon catheters and guide wires. At least four major properties determine guiding catheter support: (1) catheter intubation into the vessel, (2) catheter bends, (3) geometry and surface characteristics of the catheter’s supportive points, and (4)physical characteristics of the catheter material. Vessel intubation has been, in the experience of many operators, useful in increasing guiding catheter support [ 5 ] .This most likely results from greater catheter stability and the shortened distance that the balloon catheter and wire protrude. Coaxial alignment of the catheter with the left main coronary artery is superior to noncoaxial alignment [ 5 ] .This positioning appears to cause less injury to the vessel and better utilizes applied forces, as described below [5-71. However, further studies are needed to confirm this conclusion. When forces are transmitted in a straight line (Fig. 2a), virtually no force is lost. When forces are transmitted at an angle, force is lost (Fig. 2b). The greater the angle, the more force is lost; at 90” the loss of force transmission is complete (Fig. 2c). Changes in forces can be calculated from the following formula:
F, = F, x cos a where F, is a force entering the angle a, F, is a force exiting the angle a, and angle a is an angle between forces F, and F, (Fig. 2a,b). The clinical implication of this theory is that in a catheter with greater bends, the loss of transmitted forces is greater and, overall, the catheter provides less support. From the Baptist Medical Plaza, Oklahoma City.
Received February 8, 1992; revision accepted June 4, 1992 Address reprint requests to Jan Voda, Baptist Medical Plaza, Oklahoma City, OK 73112.
Long-TipGuiding Catheter
.
,
Judkins Cathetei
235
Amplatz Catheter
Long Tip Catheter
a
b
C
d
M = Forces generated by catheter memory LMCA = Left main coronary artery
Fig. 1. Role of catheter memory in the engagement of the left main coronary artery and common functional principles of the Judkins and long tip catheters. Fundamentaldifferences in the mechanics of reaching and engaging the left main coronary artery by the overbent and underbent catheters: a. The memory of the straight catheter bent by the aortic arch moves the catheter tip towards the aortic wall opposite the origin of the left main coronary artery. It is virtually impossible to engage this catheter in the left main coronary artery. b. When the Judkins catheter is introduced into the aortic root, the 180" secondary bend is straightened and after the wire is removed the catheter attempts to acquire its original overbent configuration. The memory of the secondary bend with help of primary bend are, thus, responsible for movement of the tip into the left main coronary artery. c. Similar to Judkins catheter, it is mainly the memory of the secondary overbend that enables the long tip catheter to reach and engage the left main coronary artery after
the wire is removed. This principle of overbent, like in the Judkins catheter, allows the long tip catheter to have a direct response to manipulations by the operator. d. The underbent catheter, for example, Amplatr catheter introduced into the aortic root, usually advances into the sinus of valsalva and below the left main coronary artery. Engagement of the left main coronary artery is accomplished by advancing the catheter, bending It further and narrowing its large distal loop. This maneuver increases the forces directed against the aortic wall and creates difflculty in manipulatingthe catheter. When the tip reaches the level of the left main coronary artery, these stored forces (memory) move the tip into the vessel, often independently of the operator's control. As a result, the underbent catheters are inherently more difficult to manipulate. In this case, it is the large distal loop of the Amplatz catheter that enables it to reach and engage the left main coronary artery.
The location of the catheter's supporting point in the aorta determines the angles at which forces and support are transmitted (Fig. 3). Maximal support, i.e., virtually no loss of force, occurs when the angle between the point of immediate support and the long axis of the left main coronary artery is 0" (Fig. 3a). The angle between the direction of forces and the aortic wall is also important. A greater angle of entry decreases the risk of supportive point or segment displacement (Fig. 4), as implied by the above formula. Another determinant of catheter support appears to be friction of the catheter at the supportive point or the force needed to displace this point. Given constant force of the catheter against the aortic wall, the larger the area of the catheter is in contact with the aortic wall the greater is the force needed to displace it (Fig. 4). One of the properties that determines catheter friction is the character of the catheter's surface. A surface that has high friction provides better stability and support for the catheter.
Not surprisingly, when the principles described above are applied in evaluating the function of the Judkins catheter in coronary angioplasty, a number of problems are identified and have been confirmed by extensive clinical experience. A 90" primary bend. Although a 90" bend at the tip facilitates engagement of the catheter in the left coronary artery, it causes poor coaxial alignment of the catheter with the left main coronary artery (Fig. 3b) and may, in some cases, completely prevent deeper intubation. Furthermore, a 90" bend causes significant loss of transmitted forces and if the primary bend were a sharp angle, the loss of forces would be complete (Fig. 2c). The upwardpointing tip may be directed opposite to the takeoff of the circumflex artery. In extreme cases, as the catheter is advanced the tip may rotate retrogradely and point toward the origin of the left main coronary artery, which makes balloon advancement virtually impossible. Location of the point of support. Typically, the point of support for the engaged Judkins catheter is considerably above the left main coronary artery, which creates a large angle between the supportive forces and the axis of the left main coronary artery and results in loss of sup-
PROBLEMS WITH THE JUDKINS CATHETER The Judkins catheter was designed for diagnostic purposes, and catheter support was not a requirement [ l].
236
Voda F 1,
Judkins Catheter
/
.ong Tip Catheter
,
Judkins Catheter
Long Tip Catheter
Fig. 4. shows relationship of the catheter position in the ascending aorta and the angles of the catheters with the aortic wall and their effect on stability and displacement of the catheter. Incoming catheter force F, is divided into force F, that presses the catheter against the aortic wall and the force F, which is vertical and causes displacement of the catheter. The greater the angle of the catheter with aortic wail (aand p), the greater the friction of the catheter and lesser chance of catheter displacement. The angle p is greater than angle a;therefore, the long tip catheter is more difficult to displace than Judkins catheter when incoming force F, is constant. F, is an incoming force of the Judkins and long tip catheters. F, is a partial force of F, pressing the catheter against the aortic wall and increasing the catheter friction. F, is a vertical force responsible for catheter displacement. a and p are angles between the aortic wall and the Judkins and long tip catheter respectively.
Fz
a
b
Fig. 3. shows more efficient use of supportive forces by long tip catheter. There is virtually no angle between the catheter force F, of the long tip catheter and the force F, applied in the left main coronary artery (shown in Figure 3a). In Figure 3b the force F, of the Judkins catheter enters the ostium of the left main coronary artery at the angle p and results in lesser force F, applied in the left main coronary artery. The steeper this angle, the greater loss of support occurs: F, is catheter force entering the left main coronary artery. F, is a transmitted catheter force through the left main coronary artery. Ps is point of support. A, is an area of support of the long tip catheter. p is an angle between the catheter and the left main coronary artery forces.
port (Figs. 3b, 4). In this arrangement, the catheter's support depends on the ability of its straightened secondary curve to close and, in general, support is reduced. This has been a major problem for the recently introduced thin-wall catheters.
Small area of support in the aorta. Support is essentially provided by a single point and the area of the catheter in contact with the aortic wall is small. The straight proximal arm creates a sharp angle between the aortic wall and the catheter, which makes the catheter more vulnerable to displacement and results in inadequate support (Fig. 4). LONG-TIP CATHETER
We designed a long-tip catheter (Figs. 5-7), taking into consideration the theoretical principles described above, and expected it to have the following capabilities: (1) coaxial intubation, (2) better support and stability, (3) precise control and manipulation, (4) lack of bends to improve advancement of devices through the lumen and to decrease the loss of supportive forces, and (5) safety. Catheter support was improved by eliminating the sharp primary bend and providing a larger, more effectively located supportive point. More precise catheter
Long-Tip Guiding Catheter FIGURE 5
aP=primary curve of 20" %=secondary ciirve of 150"-180" ?=tertiary curve of approximately 40" d l = distance between catheter tip and center of primary curve d2 = distance between center of the primary curve and outmost point of the secondary curve d j = distance between the end of the secondary curve and center of the tertiary curve approximately 1.cni i dl
=
d2 and is 2 cm. in
Fig. 5. shows a drawing of the long tip catheter.
Fig. 6. Photograph of long tip catheters (SCIMED Life Systems, Inc.) Size 3.5 cm is shown on the lefl and 4.0 cm on the right.
manipulation was achieved by overbending of the secondary curve, and better coaxial alignment with the left main coronary artery was achieved by use of a long, straight distal segment without bends. The long-tip catheter is of conventional diameter and length and is constructed of conventional materials. Its unique characteristics result from the arrangement of its three distal curves. The primary curve is shallow (- 20"), which allows for better coaxial alignment and causes less trauma during intubation of the left main coronary artery while minimizing the loss of transmitted forces. Although this angle is shallow, it elevates the catheter tip adequately to engage the left main coronary artery without difficulty (Figs. 1, 3a). The optimal location of the primary curve appears to be at the midpoint between the catheter tip and the outermost point of the secondary curve. This arrangement
237
balances the catheter, which contributes to its easy manipulation and places the supportive point into the most effective location, opposite the left main coronary artery. The long catheter tip provides greater leverage, which allows for easier changes of the primary curve, if needed, during intubation. Also, the greater reach of the catheter permits easier cannulation of left main coronary arteries with anomalous origins (e.g., posterior takeoff). The secondary curve of the catheter has a radius of 0.5 cm and it creates a 150-180" angle between the catheter arms, D2 and D3. This overbend permits good catheter response to proximal manipulation. The tertiary curve has an angle of 30-40". This angle creates a supportive segment 1.5 cm long. The steeper angle between the aorta and the catheter decreases forces that can displace the catheter (Fig. 4). The larger area of the catheter in contact with the aorta further increases resistance to displacement. This design serves a purpose similar to that of a circular base on a wineglass-stability is increased. The surface of the catheter in contact with the aorta may be best when coated with a high-friction material, but the surface was not specifically altered on catheters used in this study. The primary bend is increased to 30" on the alternative long-tip catheter with the secondary and tertiary bends unchanged (Fig. 8). This catheter is better suited for PTCA of the anterior descending artery when the left main coronary artery is short. It may also provide a better coaxial engagement and support when the vessel has a superior takeoff. METHODS The purpose of this study was to evaluate the safety and performance of the 8F long-tip guiding catheter (TRIGUIDEB) manufactured by SCIMED Life Systems (Maple Grove, MN). The 90 patients participating in the study were from 39 to 90 yr of age. The degree of complexity of the angioplasty varied, as did coronary anatomy. Nine different operators performed the procedures, and their experiences varied widely. The most experienced operator performed over 3,000 angioplasties; the least experienced operator performed less than 100 cases. A total of 89 patients underwent coronary angioplasty. In the remaining patient, who had previously undergone cardiac transplantation, the long-tip catheter was used for a diagnostic study (Fig. 9). In this patient, the posterior takeoff of the left coronary artery did not allow for proper engagement of an FL4 Judkins catheter. Of the patients who underwent angioplasty, 71 were male and 18 were female; 63 patients had multivessel disease and 30 patients had previously undergone CABG. The stenoses for which dilatation was attempted were 65%-100%. Ten were complete occlusions. Lesion locations were as follows: anterior descending artery (53), circumflex (44),protected left main coronary ar-
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Fig. 7. Shows angiograms of the left coronary artery and configurations of the 4.0 long tip catheter in following projections: A. AP; 8. RAO 29"; C. LAO 41", Cranial 40"; D. LAO 48", Caudal 24".
tery (7), intermediate artery ( 5 ) , obtuse marginal arteries (4), diagonal artery (4), and septa1 artery (1). In 86 patients, 20/40 catheters were used where the primary curve was 20" and the tertiary curve was 40". In one patient, a 30140 catheter was used, and in two patients 40/50 catheters were used. These catheters had a primary curve of 30" and 40" and a secondary curve of 40" and 50", respectively. The 4.0 cm long-tip catheter was used in 81 patients; the 4.5 cm tip was used in five patients; the 5.0 cm was used in one patient, and the 3.5 cm was used in two patients. In three patients we used a kissing balloon technique (both guiding catheters were 4.0 cm). Four patients required elective IABP support. The catheter characteristics evaluated in this study were overall manipulation and support, and stability and engagement of the left coronary artery (left main coronary, left anterior descending, or circumflex artery),
pressure damping (systolic, diastolic, or both), and degree of coaxial alignment and contrast overspill. These are subjective, yet important characteristics to evaluate. The overall success rate, complications of the procedure, and any difficulty encountered in manipulating the catheters were noted. In one patient, angiography of the aortic root was performed and recorded in the lateral view with a long-tip catheter engaged in the left main coronary artery. The purpose of this study was to demonstrate that the 1.5 cm long segment of the catheter between the secondary and tertiary curves lies against the aortic wall, as predicted (Fig. 10). RESULTS
Angioplasty was successful on 85 patients (95% success rate), and there were no major complications-no
Long-Tip Guiding Catheter
239
Fig. 8. Photograph of the alternative LAD catheter In AP projection. This catheter differs from the standard long tip catheter by steeper primary curve which is 30". Fig. 10. Aortic root anglogram recorded in the lateral view. The long tip catheter is engaged in the left main coronary artery and catheter segment between the secondary and tertiary curves lies against the aortic wall as predicted.
ter was successfully advanced into the stenosis, but inflations failed to achieve a good result. The long-tip catheter was engaged successfully in all patients and was manipulated without problems in 83 patients. In four patients, there was moderate difficulty in engaging the catheter in the left main coronary artery. In two patients, the engagement was difficult but successful. In four patients, the catheter folded up during its advancement through the ascending aorta into the left main coronary artery. This was corrected in three patients by choosing a catheter one-half size larger and in one patient by decreasing the tertiary curve from 40" to 30". Removal of the folded-up catheter required insertion of the guide wire into the catheter and the aortic root. The maneuver used was similar to that used for removal of a folded Judkins catheter. Mild pressure damping occurred in 18 patients (21%). Fig. 9. Angiogram of the lefl coronary artery shows the long tip catheter engaged in the lefl main coronary artery that has Systolic damping occurred in six patients, diastolic posterior takeoff. Note that in the RAO view the catheter tip damping occurred in four patients, and damping of both points leftward and not to the right as seen in normal takeoff of pressures occurred in eight patients. There was virtually the left coronary artery. no displacement of the guiding catheter from the left coronary artery during advancement of the balloon catheter in 65 patients. In 22 patients, there was mild disvessel closures, myocardial infarctions, emergency sur- placement and in two patients there was moderate disgery, or dissection of the left main coronary artery. In placement. Overall support was considered to be four of the cases, failure appeared not to be due to the excellent in 25 patients, very good in 57 patients, and performance of the guiding catheter. The balloon cathe- barely adequate in three patients. In these last three pa-
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Voda
FIGURE 11 Catheter S i i
cm@uration of the 1’ and 2’ arms ~~
~-
.~
Correct Size
Short Catheter
Long Catheter
PC is primary curve, PA is primary arm and SA is secondary arm. -~
.
Fig. 11. demonstratesconfigurationsof the Long, Short and a correctly sized Long Tip catheter.
tients, difficulties were attributed to nonavailability of the appropriate size catheter. In the past, we have used 70% of angioplasties of the Amplatz catheters for circumflex artery. In this study, the Amplatz catheter would have been the first choice in 35 patients; however, the Amplatz catheter was successfully replaced by the long-tip catheter.
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GUIDELINES FOR USE OF THE LONG-TIP CATHETER
Based on our overall experience, the long-tip catheter appears to be indicated for angioplasty of all stenoses in the left coronary artery. We have found the catheter to be useful even for problematic cases such as those that require considerable guiding catheter support, cases of a posterior takeoff of the left main coronary artery (unless extreme), distal lesions, and cases in which the left main coronary artery originates superiorly. The method of choosing the appropriate size long-tip catheter is similar to that for choosing a Judkins catheter. When the aortic root appears normal in size, a 4.0 long-tip catheter is appropriate. In smaller men, and particularly in women, a 3.5 long-tip is often required. Patients with a dilated aortic root or aortic stenosis require 5.0 and 6.0 long-tip catheters, respectively. The appearance of primary and secondary arms after engagement of the long-tip catheter in the left main coronary artery (Fig. 11) is an important indicator that the catheter chosen is the correct size. The technique for introducing and engaging the cath-
eter into the left main coronary artery is similar to that used for a Judkins catheter with several differences. The catheter is advanced around the aortic arch over the guide wire and then more proximally into the ascending aorta than is a Judkins catheter. After the guide wire is removed, the catheter is advanced further only after the catheter tip is horizontal or pointing downward. As with Judkins catheters, often a simple advancement of the long-tip catheter without any further manipulation results in engagement of the left main coronary artery. However, if the tip points upward while the catheter is advanced, the risk of catheter buckling is high. The catheter tip can be turned downward by clockwise rotation and upward by counterclockwise rotation. When the catheter tip is within 1” of the ostium of the left main coronary artery, advancement is usually successful no matter what the direction of the catheter tip. Slight counterclockwise or clockwise rotation may facilitate engagement of the catheter tip. The catheter can be advanced deeply into the aortic root for better support and acquire an “Amplatz” configuration. This positioning is seldom needed because the catheter provides good support from its usual position; however, if an Amplatz positioning is required, this can usually be accomplished by simple advancement of the catheter without rotation. DISCUSSION
Most currently used guiding catheters for angioplasty of the left coronary artery have curves designed by Judkins and Amplatz for diagnostic purposes. Although both types of catheters have been used successfully for angioplasty since 1977, they sometimes have significant inadequacies. In general, the Judkins catheter is responsive and allows for good control and safety but often lacks support and stability. This is particularly the case when the left main coronary artery has a steep upward takeoff, when dilatation of a distal lesion of the circumflex artery is required, or when the circumflex artery has a steep angle of origin. The Amplatz catheter, as a rule, provides very good support but may be associated with higher risks during angioplasty because it may be poorly responsive to the operator. This problem is magnified by unorthodox anatomy of the aortic root or anomalous takeoffs of the left main coronary artery. After analysis of force vectors and other factors that play a role in guiding catheter support, we arranged them efficiently and arrived at the configuration of the long-tip catheter that provides a very good catheter support. Most important of these factors are: absence of steep catheter bends, coaxial entry of the catheter into the left main coronary artery, location of the point of support directly opposite the left main coronary artery, and changed point of support to a larger area utilizing a segment of the
Long-Tip Guiding Catheter
catheter. Finally, the addition of the tertiary bend increases the overall stability and support of the long-tip catheter by directing the push of the proximal catheter into the aortic wall. In this study, the overbent long-tip catheter was easy to manipulate and control. It moved in a predictable manner and engaged well in the left main coronary artery. The 95% success rate for angioplasty of the left coronary artery in this study was equal to or better than that generally reported for this procedure and there were no serious complications as described in the results. In the majority of patients studied, we used the 4.0 longtip catheter. Since a new manufacturing process was initiated by SCIMED Life Systems, we used the long-tip catheter in over 300 patients and found that size 3.5 is preferable in most patients. Deeper intubation of the long-tip catheter into the left main coronary artery allowed more selective injection, better visualization of the vessels and lesions, and overall better support. An important question not answered in our study is whether routine coaxial intubation of the left main coronary artery is better and safer than occasional intubation with a noncoaxial catheter. It has been generally accepted philosophy that coaxial intubation of the vessels by catheters is preferable and safer [5]. However, we recommend that even catheters that engage the left main coronary artery coaxially be intubated only for a brief moment when maximal support is required. The prolonged deep intubation probably increases the risk of procedures. To minimize the potential injury to the left main coronary artery, it may be safer to use a catheter with a long soft tip (SCIMED Life Systems, Maple Grove, intermediate guiding catheter). However, this catheter may have difficulty to maintain a 20% primary curve. In this study we observed no injury to the left main coronary artery or complications related to the intubation of this vessel with the long-tip catheter. The pressure damping that occurred in 18 patients was completely eliminated or significantly improved in the majority of patients by rotating the catheter counterclockwise or, less often, clockwise and simultaneous slight withdrawal. The high incidence of pressure damping (21%) seen with the use of the long-tip catheter is probably due to the following reasons: (1) deeper catheter intubation in the left main coronary artery results in the larger portion of the lumen of the vessel being occupied by the catheter and, thus, a smaller volume of the lumen is available for blood flow; this may be a frequent cause of pressure damping; (2) the deeper intubation of the left main coronary artery may result in selective engagement of the catheter in the anterior descending or circumflex arteries, particularly when the left main coronary artery is short; these vessels, in general, have a smaller diameter than the left main coronary artery; (3) 30 patients out of 89 that we studied underwent previous
241
bypass surgery. These patients often had a diseased and small diameter left main coronary artery. Another problem that we observed with the long-tip catheter was “folding” of the catheter in the ascending aorta in four patients. This occurred at the early stage of the study when we were limited by the availability of only one catheter size. This problem can be avoided by choosing a catheter of proper size and advancing the catheter over the guide wire closer to the aortic valve than is customary with a Judkins catheter before the wire is removed. If the catheter is advanced from the midascending aorta, it is important to keep the catheter tip pointing inferiorly. This is accomplished with clockwise rotation. The last problem with the long-tip catheter seen in this study was presented by a short left main coronary artery. In this case the long-tip catheter may advance past the origin of the left anterior descending artery or point toward the circumflex artery, which creates difficulty in selecting the anterior descending artery. This problem can be corrected by use of a long-tip catheter with a primary bend of 30” or more. As with the Judkins catheter, the selective engagement of the anterior descending artery is improved by choosing a half-size shorter catheter (e.g., 3.5 instead of 4.0 catheter). In extreme cases, the Judkins catheter may be preferable for selecting the anterior descending artery because the 90” primary bend has a tendency to point towards this vessel. Since we began using the long-tip catheter for angioplasty of the left coronary artery, we have not used the Amplatz or Judkins catheters. In our experience, the long-tip catheter is an efficient and safe guiding catheter for angioplasty of the left coronary artery, which manipulates as well as the Judkins catheter and provides support and stability that nears the support of the Amplatz catheter. Although valuable information was obtained in this first evaluation of the long-tip catheter, the study has limitations. Further studies must be performed to fully understand the advantages, risks, and overall clinical value of this catheter. ACKNOWLEDGMENTS
I am greatly indebted to Judy Avers for preparing the manuscript, and to Drs. Sherali Gowani, Chandrahas Agarwal, and Keith Kassabian for their valuable help with this study. REFERENCES 1 . Judkins MP: Percutaneous transfemoral selective coronary angiography. Radio1 Clin North Am 6(3): 467-492, 1968. 2. Amplatz K, Formanek G , Stanger P, Wilson W: Mechanics of
selective coronary artery catheterization via femoral approach. Radiology 89: 1040-1047, 1967.
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3. El Gamal MIH, Bonnier JJRM, Michels HR, van Gelder LM: Improved success rate of percutaneous transluminal graft and coronary angioplasty with the El Gamal guiding catheter. Cathet Cardiovasc Diagn l l: 89-96, 1985. 4. Nesto RW: Performance characteristics of a new shape of guiding catheter for PTCA of the left coronary artery. Cathet Cardiovasc Diagn 24: 144-148, 1991. 5 . Carr ML: The use of the guiding catheter in coronary angioplasty: The techniques of manipulating catheters to obtain the necessary
power to cross tight coronary stenoses. Cathet Cardiovasc Diagn 12: 189-197, 1986.
6. Wayne VS, Harper RW, Pitt A: Left main coronary artery stenosis after percutaneous transluminal coronary angioplasty. Am J Cardiol 61: 450-460, 1988. 7. Kells CM, Miller RM, Henderson MA, Lomnicki JM, MacDonald RG: Left main coronary a e r y disease progression after percutaneous transluminal coronary angioplasty. Am J Cardiol 65: 513514, 1990.
Long-Tip Guiding Catheter: Successful and Safe for Left Coronary Artery Angioplasty Jan Voda, MD A long-tip guiding catheter was designed for angioplasty of the left coronary artery. Principal factors of guiding catheter function were identified, and the catheter’s shape was designed to utilize them efficiently. Emphasis was placed on an overbent secondary curve (150-180’) for more precise catheter control. The distal tip of the catheter is 2 cm long in the 4.0 size and the 20%. A 1.5 cm long segment beprimary bend is shallow, tween the secondary and tertiary curves enhances stability and support. Catheter performance was studied during procedures on 90 patients; 89 patients underwent coronary artery angioplasty and one patient underwent diagnostic angiography. The success rate for angioplasty was 95% with no major complications, Mild pressure damping occurred in 18 patients, and mild catheter displacement from the left main coronary artery occurred in 24 patients. Catheter support was judged as excellent to very good in 82 patients. Judkins or Amplatz catheters were not required during this study. The observed disadvantages of the long-tip catheter were the risk of catheter buckling up during advancement into the left main coronary artery and, perhaps, a higher risk of pressure damping. Superselective engagement of the catheter in the left anterior descending or circumflex arteries may be a problem when the left main coronary artery is very short. This study showed the long-tip catheter to be safe and highly successful for angioplasty of the left coronary artery. o 1992 wiiey-Liss, 111c.
-
Key words: guiding coronary artery
catheter,
coronary angioplasty,
left
INTRODUCTION
Today’s guiding catheters for angioplasty of the left coronary artery originated from diagnostic catheters, and they have been used with considerable success and safety for many years. Essentially unchanged shapes of Judkins and Amplatz [ 1.21 diagnostic catheters are still most frequently used; however, the role of guiding catheters is fundamentally different from that of diagnostic catheters. Therefore, it is not surprising that in many cases the performance of these guiding catheters is not adequate. In terms of functional differences between Judkins and Amplatz catheters, currently used diagnostic and guiding catheters can be classified into two groups-those with distal curves that are overbent or underbent prior to their insertion into the circulation. Importantly, the catheters have “memory,” which could be defined as a tendency to keep or resume original configuration. The memory is an additional useful factor in manipulation of the catheters and plays a major role in engagement of the Judkins, 0 1992 Wiley-Liss, Inc.
long-tip, or Amplatz catheters into the left main coronary artery (Fig. 1). There are important differences in response and manipulation of the overbent and underbent catheters. Inherently, the overbent catheters have good and predictable response, whereas underbent catheters may be difficult to manipulate. This is the principal reason why the Judkins catheter is the most popular in diagnostic studies and as a guiding catheter in angioplasties. This is also the main reason why we selected the overbent principle for design of the long-tip catheter. THEORETICAL ANALYSIS
An important function of guiding catheters is support of devices such as balloon catheters and guide wires. At least four major properties determine guiding catheter support: (1) catheter intubation into the vessel, (2) catheter bends, (3) geometry and surface characteristics of the catheter’s supportive points, and (4)physical characteristics of the catheter material. Vessel intubation has been, in the experience of many operators, useful in increasing guiding catheter support [ 5 ] .This most likely results from greater catheter stability and the shortened distance that the balloon catheter and wire protrude. Coaxial alignment of the catheter with the left main coronary artery is superior to noncoaxial alignment [ 5 ] .This positioning appears to cause less injury to the vessel and better utilizes applied forces, as described below [5-71. However, further studies are needed to confirm this conclusion. When forces are transmitted in a straight line (Fig. 2a), virtually no force is lost. When forces are transmitted at an angle, force is lost (Fig. 2b). The greater the angle, the more force is lost; at 90” the loss of force transmission is complete (Fig. 2c). Changes in forces can be calculated from the following formula:
F, = F, x cos a where F, is a force entering the angle a, F, is a force exiting the angle a, and angle a is an angle between forces F, and F, (Fig. 2a,b). The clinical implication of this theory is that in a catheter with greater bends, the loss of transmitted forces is greater and, overall, the catheter provides less support. From the Baptist Medical Plaza, Oklahoma City.
Received February 8, 1992; revision accepted June 4, 1992 Address reprint requests to Jan Voda, Baptist Medical Plaza, Oklahoma City, OK 73112.
Long-TipGuiding Catheter
.
,
Judkins Cathetei
235
Amplatz Catheter
Long Tip Catheter
a
b
C
d
M = Forces generated by catheter memory LMCA = Left main coronary artery
Fig. 1. Role of catheter memory in the engagement of the left main coronary artery and common functional principles of the Judkins and long tip catheters. Fundamentaldifferences in the mechanics of reaching and engaging the left main coronary artery by the overbent and underbent catheters: a. The memory of the straight catheter bent by the aortic arch moves the catheter tip towards the aortic wall opposite the origin of the left main coronary artery. It is virtually impossible to engage this catheter in the left main coronary artery. b. When the Judkins catheter is introduced into the aortic root, the 180" secondary bend is straightened and after the wire is removed the catheter attempts to acquire its original overbent configuration. The memory of the secondary bend with help of primary bend are, thus, responsible for movement of the tip into the left main coronary artery. c. Similar to Judkins catheter, it is mainly the memory of the secondary overbend that enables the long tip catheter to reach and engage the left main coronary artery after
the wire is removed. This principle of overbent, like in the Judkins catheter, allows the long tip catheter to have a direct response to manipulations by the operator. d. The underbent catheter, for example, Amplatr catheter introduced into the aortic root, usually advances into the sinus of valsalva and below the left main coronary artery. Engagement of the left main coronary artery is accomplished by advancing the catheter, bending It further and narrowing its large distal loop. This maneuver increases the forces directed against the aortic wall and creates difflculty in manipulatingthe catheter. When the tip reaches the level of the left main coronary artery, these stored forces (memory) move the tip into the vessel, often independently of the operator's control. As a result, the underbent catheters are inherently more difficult to manipulate. In this case, it is the large distal loop of the Amplatz catheter that enables it to reach and engage the left main coronary artery.
The location of the catheter's supporting point in the aorta determines the angles at which forces and support are transmitted (Fig. 3). Maximal support, i.e., virtually no loss of force, occurs when the angle between the point of immediate support and the long axis of the left main coronary artery is 0" (Fig. 3a). The angle between the direction of forces and the aortic wall is also important. A greater angle of entry decreases the risk of supportive point or segment displacement (Fig. 4), as implied by the above formula. Another determinant of catheter support appears to be friction of the catheter at the supportive point or the force needed to displace this point. Given constant force of the catheter against the aortic wall, the larger the area of the catheter is in contact with the aortic wall the greater is the force needed to displace it (Fig. 4). One of the properties that determines catheter friction is the character of the catheter's surface. A surface that has high friction provides better stability and support for the catheter.
Not surprisingly, when the principles described above are applied in evaluating the function of the Judkins catheter in coronary angioplasty, a number of problems are identified and have been confirmed by extensive clinical experience. A 90" primary bend. Although a 90" bend at the tip facilitates engagement of the catheter in the left coronary artery, it causes poor coaxial alignment of the catheter with the left main coronary artery (Fig. 3b) and may, in some cases, completely prevent deeper intubation. Furthermore, a 90" bend causes significant loss of transmitted forces and if the primary bend were a sharp angle, the loss of forces would be complete (Fig. 2c). The upwardpointing tip may be directed opposite to the takeoff of the circumflex artery. In extreme cases, as the catheter is advanced the tip may rotate retrogradely and point toward the origin of the left main coronary artery, which makes balloon advancement virtually impossible. Location of the point of support. Typically, the point of support for the engaged Judkins catheter is considerably above the left main coronary artery, which creates a large angle between the supportive forces and the axis of the left main coronary artery and results in loss of sup-
PROBLEMS WITH THE JUDKINS CATHETER The Judkins catheter was designed for diagnostic purposes, and catheter support was not a requirement [ l].
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Judkins Catheter
/
.ong Tip Catheter
,
Judkins Catheter
Long Tip Catheter
Fig. 4. shows relationship of the catheter position in the ascending aorta and the angles of the catheters with the aortic wall and their effect on stability and displacement of the catheter. Incoming catheter force F, is divided into force F, that presses the catheter against the aortic wall and the force F, which is vertical and causes displacement of the catheter. The greater the angle of the catheter with aortic wail (aand p), the greater the friction of the catheter and lesser chance of catheter displacement. The angle p is greater than angle a;therefore, the long tip catheter is more difficult to displace than Judkins catheter when incoming force F, is constant. F, is an incoming force of the Judkins and long tip catheters. F, is a partial force of F, pressing the catheter against the aortic wall and increasing the catheter friction. F, is a vertical force responsible for catheter displacement. a and p are angles between the aortic wall and the Judkins and long tip catheter respectively.
Fz
a
b
Fig. 3. shows more efficient use of supportive forces by long tip catheter. There is virtually no angle between the catheter force F, of the long tip catheter and the force F, applied in the left main coronary artery (shown in Figure 3a). In Figure 3b the force F, of the Judkins catheter enters the ostium of the left main coronary artery at the angle p and results in lesser force F, applied in the left main coronary artery. The steeper this angle, the greater loss of support occurs: F, is catheter force entering the left main coronary artery. F, is a transmitted catheter force through the left main coronary artery. Ps is point of support. A, is an area of support of the long tip catheter. p is an angle between the catheter and the left main coronary artery forces.
port (Figs. 3b, 4). In this arrangement, the catheter's support depends on the ability of its straightened secondary curve to close and, in general, support is reduced. This has been a major problem for the recently introduced thin-wall catheters.
Small area of support in the aorta. Support is essentially provided by a single point and the area of the catheter in contact with the aortic wall is small. The straight proximal arm creates a sharp angle between the aortic wall and the catheter, which makes the catheter more vulnerable to displacement and results in inadequate support (Fig. 4). LONG-TIP CATHETER
We designed a long-tip catheter (Figs. 5-7), taking into consideration the theoretical principles described above, and expected it to have the following capabilities: (1) coaxial intubation, (2) better support and stability, (3) precise control and manipulation, (4) lack of bends to improve advancement of devices through the lumen and to decrease the loss of supportive forces, and (5) safety. Catheter support was improved by eliminating the sharp primary bend and providing a larger, more effectively located supportive point. More precise catheter
Long-Tip Guiding Catheter FIGURE 5
aP=primary curve of 20" %=secondary ciirve of 150"-180" ?=tertiary curve of approximately 40" d l = distance between catheter tip and center of primary curve d2 = distance between center of the primary curve and outmost point of the secondary curve d j = distance between the end of the secondary curve and center of the tertiary curve approximately 1.cni i dl
=
d2 and is 2 cm. in
Fig. 5. shows a drawing of the long tip catheter.
Fig. 6. Photograph of long tip catheters (SCIMED Life Systems, Inc.) Size 3.5 cm is shown on the lefl and 4.0 cm on the right.
manipulation was achieved by overbending of the secondary curve, and better coaxial alignment with the left main coronary artery was achieved by use of a long, straight distal segment without bends. The long-tip catheter is of conventional diameter and length and is constructed of conventional materials. Its unique characteristics result from the arrangement of its three distal curves. The primary curve is shallow (- 20"), which allows for better coaxial alignment and causes less trauma during intubation of the left main coronary artery while minimizing the loss of transmitted forces. Although this angle is shallow, it elevates the catheter tip adequately to engage the left main coronary artery without difficulty (Figs. 1, 3a). The optimal location of the primary curve appears to be at the midpoint between the catheter tip and the outermost point of the secondary curve. This arrangement
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balances the catheter, which contributes to its easy manipulation and places the supportive point into the most effective location, opposite the left main coronary artery. The long catheter tip provides greater leverage, which allows for easier changes of the primary curve, if needed, during intubation. Also, the greater reach of the catheter permits easier cannulation of left main coronary arteries with anomalous origins (e.g., posterior takeoff). The secondary curve of the catheter has a radius of 0.5 cm and it creates a 150-180" angle between the catheter arms, D2 and D3. This overbend permits good catheter response to proximal manipulation. The tertiary curve has an angle of 30-40". This angle creates a supportive segment 1.5 cm long. The steeper angle between the aorta and the catheter decreases forces that can displace the catheter (Fig. 4). The larger area of the catheter in contact with the aorta further increases resistance to displacement. This design serves a purpose similar to that of a circular base on a wineglass-stability is increased. The surface of the catheter in contact with the aorta may be best when coated with a high-friction material, but the surface was not specifically altered on catheters used in this study. The primary bend is increased to 30" on the alternative long-tip catheter with the secondary and tertiary bends unchanged (Fig. 8). This catheter is better suited for PTCA of the anterior descending artery when the left main coronary artery is short. It may also provide a better coaxial engagement and support when the vessel has a superior takeoff. METHODS The purpose of this study was to evaluate the safety and performance of the 8F long-tip guiding catheter (TRIGUIDEB) manufactured by SCIMED Life Systems (Maple Grove, MN). The 90 patients participating in the study were from 39 to 90 yr of age. The degree of complexity of the angioplasty varied, as did coronary anatomy. Nine different operators performed the procedures, and their experiences varied widely. The most experienced operator performed over 3,000 angioplasties; the least experienced operator performed less than 100 cases. A total of 89 patients underwent coronary angioplasty. In the remaining patient, who had previously undergone cardiac transplantation, the long-tip catheter was used for a diagnostic study (Fig. 9). In this patient, the posterior takeoff of the left coronary artery did not allow for proper engagement of an FL4 Judkins catheter. Of the patients who underwent angioplasty, 71 were male and 18 were female; 63 patients had multivessel disease and 30 patients had previously undergone CABG. The stenoses for which dilatation was attempted were 65%-100%. Ten were complete occlusions. Lesion locations were as follows: anterior descending artery (53), circumflex (44),protected left main coronary ar-
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Fig. 7. Shows angiograms of the left coronary artery and configurations of the 4.0 long tip catheter in following projections: A. AP; 8. RAO 29"; C. LAO 41", Cranial 40"; D. LAO 48", Caudal 24".
tery (7), intermediate artery ( 5 ) , obtuse marginal arteries (4), diagonal artery (4), and septa1 artery (1). In 86 patients, 20/40 catheters were used where the primary curve was 20" and the tertiary curve was 40". In one patient, a 30140 catheter was used, and in two patients 40/50 catheters were used. These catheters had a primary curve of 30" and 40" and a secondary curve of 40" and 50", respectively. The 4.0 cm long-tip catheter was used in 81 patients; the 4.5 cm tip was used in five patients; the 5.0 cm was used in one patient, and the 3.5 cm was used in two patients. In three patients we used a kissing balloon technique (both guiding catheters were 4.0 cm). Four patients required elective IABP support. The catheter characteristics evaluated in this study were overall manipulation and support, and stability and engagement of the left coronary artery (left main coronary, left anterior descending, or circumflex artery),
pressure damping (systolic, diastolic, or both), and degree of coaxial alignment and contrast overspill. These are subjective, yet important characteristics to evaluate. The overall success rate, complications of the procedure, and any difficulty encountered in manipulating the catheters were noted. In one patient, angiography of the aortic root was performed and recorded in the lateral view with a long-tip catheter engaged in the left main coronary artery. The purpose of this study was to demonstrate that the 1.5 cm long segment of the catheter between the secondary and tertiary curves lies against the aortic wall, as predicted (Fig. 10). RESULTS
Angioplasty was successful on 85 patients (95% success rate), and there were no major complications-no
Long-Tip Guiding Catheter
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Fig. 8. Photograph of the alternative LAD catheter In AP projection. This catheter differs from the standard long tip catheter by steeper primary curve which is 30". Fig. 10. Aortic root anglogram recorded in the lateral view. The long tip catheter is engaged in the left main coronary artery and catheter segment between the secondary and tertiary curves lies against the aortic wall as predicted.
ter was successfully advanced into the stenosis, but inflations failed to achieve a good result. The long-tip catheter was engaged successfully in all patients and was manipulated without problems in 83 patients. In four patients, there was moderate difficulty in engaging the catheter in the left main coronary artery. In two patients, the engagement was difficult but successful. In four patients, the catheter folded up during its advancement through the ascending aorta into the left main coronary artery. This was corrected in three patients by choosing a catheter one-half size larger and in one patient by decreasing the tertiary curve from 40" to 30". Removal of the folded-up catheter required insertion of the guide wire into the catheter and the aortic root. The maneuver used was similar to that used for removal of a folded Judkins catheter. Mild pressure damping occurred in 18 patients (21%). Fig. 9. Angiogram of the lefl coronary artery shows the long tip catheter engaged in the lefl main coronary artery that has Systolic damping occurred in six patients, diastolic posterior takeoff. Note that in the RAO view the catheter tip damping occurred in four patients, and damping of both points leftward and not to the right as seen in normal takeoff of pressures occurred in eight patients. There was virtually the left coronary artery. no displacement of the guiding catheter from the left coronary artery during advancement of the balloon catheter in 65 patients. In 22 patients, there was mild disvessel closures, myocardial infarctions, emergency sur- placement and in two patients there was moderate disgery, or dissection of the left main coronary artery. In placement. Overall support was considered to be four of the cases, failure appeared not to be due to the excellent in 25 patients, very good in 57 patients, and performance of the guiding catheter. The balloon cathe- barely adequate in three patients. In these last three pa-
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FIGURE 11 Catheter S i i
cm@uration of the 1’ and 2’ arms ~~
~-
.~
Correct Size
Short Catheter
Long Catheter
PC is primary curve, PA is primary arm and SA is secondary arm. -~
.
Fig. 11. demonstratesconfigurationsof the Long, Short and a correctly sized Long Tip catheter.
tients, difficulties were attributed to nonavailability of the appropriate size catheter. In the past, we have used 70% of angioplasties of the Amplatz catheters for circumflex artery. In this study, the Amplatz catheter would have been the first choice in 35 patients; however, the Amplatz catheter was successfully replaced by the long-tip catheter.
-
GUIDELINES FOR USE OF THE LONG-TIP CATHETER
Based on our overall experience, the long-tip catheter appears to be indicated for angioplasty of all stenoses in the left coronary artery. We have found the catheter to be useful even for problematic cases such as those that require considerable guiding catheter support, cases of a posterior takeoff of the left main coronary artery (unless extreme), distal lesions, and cases in which the left main coronary artery originates superiorly. The method of choosing the appropriate size long-tip catheter is similar to that for choosing a Judkins catheter. When the aortic root appears normal in size, a 4.0 long-tip catheter is appropriate. In smaller men, and particularly in women, a 3.5 long-tip is often required. Patients with a dilated aortic root or aortic stenosis require 5.0 and 6.0 long-tip catheters, respectively. The appearance of primary and secondary arms after engagement of the long-tip catheter in the left main coronary artery (Fig. 11) is an important indicator that the catheter chosen is the correct size. The technique for introducing and engaging the cath-
eter into the left main coronary artery is similar to that used for a Judkins catheter with several differences. The catheter is advanced around the aortic arch over the guide wire and then more proximally into the ascending aorta than is a Judkins catheter. After the guide wire is removed, the catheter is advanced further only after the catheter tip is horizontal or pointing downward. As with Judkins catheters, often a simple advancement of the long-tip catheter without any further manipulation results in engagement of the left main coronary artery. However, if the tip points upward while the catheter is advanced, the risk of catheter buckling is high. The catheter tip can be turned downward by clockwise rotation and upward by counterclockwise rotation. When the catheter tip is within 1” of the ostium of the left main coronary artery, advancement is usually successful no matter what the direction of the catheter tip. Slight counterclockwise or clockwise rotation may facilitate engagement of the catheter tip. The catheter can be advanced deeply into the aortic root for better support and acquire an “Amplatz” configuration. This positioning is seldom needed because the catheter provides good support from its usual position; however, if an Amplatz positioning is required, this can usually be accomplished by simple advancement of the catheter without rotation. DISCUSSION
Most currently used guiding catheters for angioplasty of the left coronary artery have curves designed by Judkins and Amplatz for diagnostic purposes. Although both types of catheters have been used successfully for angioplasty since 1977, they sometimes have significant inadequacies. In general, the Judkins catheter is responsive and allows for good control and safety but often lacks support and stability. This is particularly the case when the left main coronary artery has a steep upward takeoff, when dilatation of a distal lesion of the circumflex artery is required, or when the circumflex artery has a steep angle of origin. The Amplatz catheter, as a rule, provides very good support but may be associated with higher risks during angioplasty because it may be poorly responsive to the operator. This problem is magnified by unorthodox anatomy of the aortic root or anomalous takeoffs of the left main coronary artery. After analysis of force vectors and other factors that play a role in guiding catheter support, we arranged them efficiently and arrived at the configuration of the long-tip catheter that provides a very good catheter support. Most important of these factors are: absence of steep catheter bends, coaxial entry of the catheter into the left main coronary artery, location of the point of support directly opposite the left main coronary artery, and changed point of support to a larger area utilizing a segment of the
Long-Tip Guiding Catheter
catheter. Finally, the addition of the tertiary bend increases the overall stability and support of the long-tip catheter by directing the push of the proximal catheter into the aortic wall. In this study, the overbent long-tip catheter was easy to manipulate and control. It moved in a predictable manner and engaged well in the left main coronary artery. The 95% success rate for angioplasty of the left coronary artery in this study was equal to or better than that generally reported for this procedure and there were no serious complications as described in the results. In the majority of patients studied, we used the 4.0 longtip catheter. Since a new manufacturing process was initiated by SCIMED Life Systems, we used the long-tip catheter in over 300 patients and found that size 3.5 is preferable in most patients. Deeper intubation of the long-tip catheter into the left main coronary artery allowed more selective injection, better visualization of the vessels and lesions, and overall better support. An important question not answered in our study is whether routine coaxial intubation of the left main coronary artery is better and safer than occasional intubation with a noncoaxial catheter. It has been generally accepted philosophy that coaxial intubation of the vessels by catheters is preferable and safer [5]. However, we recommend that even catheters that engage the left main coronary artery coaxially be intubated only for a brief moment when maximal support is required. The prolonged deep intubation probably increases the risk of procedures. To minimize the potential injury to the left main coronary artery, it may be safer to use a catheter with a long soft tip (SCIMED Life Systems, Maple Grove, intermediate guiding catheter). However, this catheter may have difficulty to maintain a 20% primary curve. In this study we observed no injury to the left main coronary artery or complications related to the intubation of this vessel with the long-tip catheter. The pressure damping that occurred in 18 patients was completely eliminated or significantly improved in the majority of patients by rotating the catheter counterclockwise or, less often, clockwise and simultaneous slight withdrawal. The high incidence of pressure damping (21%) seen with the use of the long-tip catheter is probably due to the following reasons: (1) deeper catheter intubation in the left main coronary artery results in the larger portion of the lumen of the vessel being occupied by the catheter and, thus, a smaller volume of the lumen is available for blood flow; this may be a frequent cause of pressure damping; (2) the deeper intubation of the left main coronary artery may result in selective engagement of the catheter in the anterior descending or circumflex arteries, particularly when the left main coronary artery is short; these vessels, in general, have a smaller diameter than the left main coronary artery; (3) 30 patients out of 89 that we studied underwent previous
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bypass surgery. These patients often had a diseased and small diameter left main coronary artery. Another problem that we observed with the long-tip catheter was “folding” of the catheter in the ascending aorta in four patients. This occurred at the early stage of the study when we were limited by the availability of only one catheter size. This problem can be avoided by choosing a catheter of proper size and advancing the catheter over the guide wire closer to the aortic valve than is customary with a Judkins catheter before the wire is removed. If the catheter is advanced from the midascending aorta, it is important to keep the catheter tip pointing inferiorly. This is accomplished with clockwise rotation. The last problem with the long-tip catheter seen in this study was presented by a short left main coronary artery. In this case the long-tip catheter may advance past the origin of the left anterior descending artery or point toward the circumflex artery, which creates difficulty in selecting the anterior descending artery. This problem can be corrected by use of a long-tip catheter with a primary bend of 30” or more. As with the Judkins catheter, the selective engagement of the anterior descending artery is improved by choosing a half-size shorter catheter (e.g., 3.5 instead of 4.0 catheter). In extreme cases, the Judkins catheter may be preferable for selecting the anterior descending artery because the 90” primary bend has a tendency to point towards this vessel. Since we began using the long-tip catheter for angioplasty of the left coronary artery, we have not used the Amplatz or Judkins catheters. In our experience, the long-tip catheter is an efficient and safe guiding catheter for angioplasty of the left coronary artery, which manipulates as well as the Judkins catheter and provides support and stability that nears the support of the Amplatz catheter. Although valuable information was obtained in this first evaluation of the long-tip catheter, the study has limitations. Further studies must be performed to fully understand the advantages, risks, and overall clinical value of this catheter. ACKNOWLEDGMENTS
I am greatly indebted to Judy Avers for preparing the manuscript, and to Drs. Sherali Gowani, Chandrahas Agarwal, and Keith Kassabian for their valuable help with this study. REFERENCES 1 . Judkins MP: Percutaneous transfemoral selective coronary angiography. Radio1 Clin North Am 6(3): 467-492, 1968. 2. Amplatz K, Formanek G , Stanger P, Wilson W: Mechanics of
selective coronary artery catheterization via femoral approach. Radiology 89: 1040-1047, 1967.
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3. El Gamal MIH, Bonnier JJRM, Michels HR, van Gelder LM: Improved success rate of percutaneous transluminal graft and coronary angioplasty with the El Gamal guiding catheter. Cathet Cardiovasc Diagn l l: 89-96, 1985. 4. Nesto RW: Performance characteristics of a new shape of guiding catheter for PTCA of the left coronary artery. Cathet Cardiovasc Diagn 24: 144-148, 1991. 5 . Carr ML: The use of the guiding catheter in coronary angioplasty: The techniques of manipulating catheters to obtain the necessary
power to cross tight coronary stenoses. Cathet Cardiovasc Diagn 12: 189-197, 1986.
6. Wayne VS, Harper RW, Pitt A: Left main coronary artery stenosis after percutaneous transluminal coronary angioplasty. Am J Cardiol 61: 450-460, 1988. 7. Kells CM, Miller RM, Henderson MA, Lomnicki JM, MacDonald RG: Left main coronary a e r y disease progression after percutaneous transluminal coronary angioplasty. Am J Cardiol 65: 513514, 1990.
