M-Mode Echocardiogra.phy in Evaluating left Ve.nt-ricular Function and Surgical Risk in Patients with Coronary Artery Disease* Betty C. Corya, M.D.; 00 Swan Rasmwsen, R.N., M.S.N.;t Suzanne B. Knoebel, M.D.;:j: and Harvey Feigenbaum, M.D.:j:
Echocardiograpbic left ventricular size and closure time of the mitral valve were measured in 204 consecutive patients having cardiac catheterization and significant coronary artery disease to determine if these measurements could assess the extent of left ventricular dysfunction and predict surgical mortality for those patients treated surgically. Among 30 patients having both an echocardiographically increased left ventricular internal dimension at the end of diastole and a prolonged time of mitral valve closure, left ventriculographic studies showed greater than 40 percent abnormality of wall motion in 24 patients (80 percent), and the resting left ventricular end-diastoUc pressure averaged 23 mm Hg. Of the remaining 174 patients, only 13 (7 percent)
had greater than 40 percent abnormality of wall motion, and the left ventricular end-diastoUc pressure averaged 11 mm Hg. Eighty-six of the 204 patients received surgical therapy. Mortality during hospitalization for those surgical patients with both echocardiographic findings was 67 percent (6/9) compared to 1 percent (1177) for those without both findings (P < 0.001). The combination of an echocardiographkally increased left ventricular diastoUc dimension together with a prolonged mitral valve closure (1) correlates with extensive abnormalities of wall motion and elevated left ventricular enddiastoUc pressure at cardiac catheterization, and (2) is associated with an increased surgical risk.
previous studies have shown that mortality during hospitalization following surgery for coronary artery disease is closely related to the preoperative state of ventricular function. 1•7 Elevated left ventricular end-diastolic pressure, 5-8 an abnormal pattern of contraction, 6 a decreased contractile state (as measured by the ejection fraction), 9 and congestive heart failure 8•10- 12 have all been demonstrated to increase the surgical risk; and patients are often rejected as surgical candidates when studies by cardiac catheterization reveal such abnormalities. 4 •13•14 The purpose of this investigation was to evaluate the clinical usefulness of M-mode echocardiographic studies in assessing the extent of left ventricular dysfunction and identifying high-risk surgical patients.
MATERIALS AND METHODS
Two hundred four consecutive patients with significant coronary artery disease ( 75 percent or greater narrowing of at least one coronary artery) were included in this study. For the purpose of this study, an adequate echocardiograrn was defined as one from which both the left ventricular diastolic internal dimension and the closure time of the mitral valve could be measured. Six patients were excluded due to inadequate echocardiograms. There were 172 men and 32 women. Ages ranged from 30 to 67 years, with a mean of 51 years. Of the total group, 103 patients (50 percent) had a history of prior myocardial infarction. None of the patients had undergone surgery previously for coronary artery disease or its complications.
°From the Krannert Institute of Cardiology the Department of Medicine, Indiana University Schoof of Medicine, and the Veterans Administration Haspital, Indianapolis. Supported in part by the Herman C. Krannert Fund; by grants HL-06308, HL-05363, and HL-07182 from the National Heart and Lung Institute; by the American Heart Association, Indiana Affiliate; and by the Veterans Administration. • • Associate Professor of Medicine. tAssistant Professor of Cardiovascular Research. · !Professor of Medicine. Manuscript received August 19; revision accepted December3. Reprint requests: Dr. C01'fla, Indiana University School of Medicine, Indianapolis 46202
All patients were examined with an echocardiograph (Smith-Kline) having a repetition rate of 1,000 pulses per second and utilizing a 2.25 MHz transducer with a 12 mm crystal collimated to 7.5 em. All echocardiograms were obtained on the day prior to cardiac catheterization and were recorded on either a multichannel strip-chart recorder ( Electronics for Medicine) or a portable strip-chart recorder ( Honeywell 1856). A simultaneous electrocardiographic monitoring lead was recorded on each tracing. The echocardiographic left ventricular measurements were made from recordings taken from the fourth or fifth intercostal space. The left ventricular internal dimension at the end of diastole was taken at the peak of the R wave on the electrocardiogram
CHEST, 72: 2, AUGUST, 1977
Clinical Data
Echocardiograms
M-MODE ECHOCARDIOGRAPHY 181
at or below the level of the posterior leaHet of the mitral valve ( Fig 1 ) . This echocardiographic location has been found to best reflect left septal and posterior left ventricular endocardial echoes. 15 The peak of the R wave, which has been shown to correspond to the mechanical onset of left ventricular contraction in normal patients, 1 6 was used to determine the end of diastole. This dimension was divided by the body surface area to obtain an index of the end-diastolic left ventricular internal dimension. The normal value of this index in our laboratory is 3.2 cm/sq m or less. The period of mitral valve closure ( AC) was measured from the peak of the A wave on the echocardiogram of the mitral valve to the point where the echoes from the anterior and posterior mitral leaflets met. Abnormal mitral valve closure was defined as an electrocardiographic P-R interval minus the echocardiographic AC interval (PR-AC) of 0.06 second or less ( Fig 2) . Cardiac Catheterization
AU patients underwent cardiac catheterization, including selective coronary cineangiographic and left ventriculographic studies, for the evaluation of chest pain or the feasibility of surgical therapy. Left ventricular end-diastolic pressure was measured prior to cineangiographic study. The left ventricular angiographic studies were performed in the right anterior oblique projection. Assessment of the pattern of ventricular contraction was done without knowledge of the echocardio-
NORMAL FIGURE 2. Echocardiograms of mitral valve, showing normal and prolonged mitral valve closure time. Mitral valve closure is normal when electrocardiographic P-R interval minus mitral valve A-C interval exceeds 0.06 second. graphic findings. The ventriculogram was divided into five segments, as follows: anterobasal, anterolateral, apical, diaphragmatic, and posterobasal. 17 Each of the five segments was evaluated and classifled as either normal or abnormal. A segment was called abnormal if motion was reduced (amplitude less than normal), absent, dyskinetic (paradoxical), or aneurysmal (bulging with sharply defined margins of the indicated segment) .1r Based on the sum of abnormally contracting segments, the ventriculogram was classified into one of the following three categories: ( 1 ) normal (zero abnormal segments) ; (2) segmentally abnormal, ie, with one or two segments being abnormal ( 40 percent or loss of the left ventricular perimeter); or ( 3) extensively abnormal, with three or more zones being abnormal ( greater than 40 percent of the perimeter). Surgical Group
FIGURE 1. Left ventriCular echocardiogram, showing where left ventricular internal dimension at end of diastole ( LVIDd) was measured between left septal ( LS) and posterior endocardial ( EN ) echoes.
182 CORYA ET AL
Eighty-six of the 204 patients subsequently underwent surgery using cardiopulmonary bypass and moderate hypothermia (29•c to 32•c [84.2°F to 89.6.F]). Twenty-three patients had coronary artery bypass grafting of a single vessel; 33 patients had double-vessel bypass; 16 patients
CHEST, 72: 2, AUGUST, 1977
had triple-vessel bypass; four patients had single-vessel bypass with myocardial resection; four patients had doublevessel bypass with myocardial resection; and six patients had myocardial resection only. Of the total 149 bypass grafts, the saphenous vein was used for 131 and the internal mammary artery was used for 18. Gas endarterectomy was included in the surgery in three patients.
Statistical Analysis Student's t-test was used to analyze the difference between groups for means of left ventricular end-diastolic pressure. Chi-square analysis was used to determine if a relationship existed between the echocardiographic measurements of left ventricular size and mitral valve closure and either ( 1 ) the left ventricular end-diastolic pressures and wall motion as assessed by cardiac catheterization or ( 2) mortality during hospitalization for those patients subsequently undergoing surgery. In addition, chi-square analysis was utilized to determine if there was a relationship between surgical mortality and ( 1 ) the history of myocardial infarction, ( 2) a left ventricular end-diastolic pressure ~ 20 mm Hg, ( 3) the extent of abnormal contraction by ventriculographic studies, ( 4) the number of vessels bypassed, and ( 5) myocardial resection. Mortality during hospitalization included all patients who died between induction of anesthesia and discharge from the hospital. REsULTS
Echocardiographic Data
Both the left ventricular dimension and Closure time of the mitral valve were normal in 102 of the 204 patients. Of the remaining 102 patients, 45 had a normal left ventricular dimension but abnormal mitral valve closure, 27 patients had an increased left ventricular dimension with normal mitral valve closure, and 30 patients had both abnormalities, ie, an increased left ventricular dimension and abnormal mitral valve closure. Data from Cardiac Catheterization
Of the 204 patients, 72 had single-vessel disease, 63 had two-vessel disease, and 69 had three-vessel disease. The resting left ventricular end-diastolic pressure for the 204 patients ranged from 0 to 38 mm Hg (mean, 12 mm Hg). As judged by left ventriculographic studies, the pattern of left ventricular contraction was normal in 66 patients; segmental abnormalities ( 40 percent or less) were noted in 101 patients; and extensive abnormalities (greater than 40 percent) were evident in 37 patients. Echocardiograms and Cardiac Catheterization
The echocardiographic findings and data from cardiac catheterization are summarized in Table 1. Between the groups of patients whose echocardiographic findings were either normal or showed only one of the two echocardiographic abnormalities, CHEST, 72: 2, AUGUST, 1977
there was no significant statistical difference in either the mean left ventricular end-diastolic pressure or in the ventriculographic pattern of contraction; however, both the left ventricular end-diastolic pressure and the extent of the abnormalities of contraction were significantly greater in the group of patients with both echocardiographic abnormalities ( P < 0.001). Among the 30 patients with both echocardiographic abnormalities, the left ventricular end-diastolic pressure averaged 23 mm Hg, and 80 percent (24/30) of the group had extensive abnormalities of contraction by left ventriculographic studies. Of the 174 patients without both echocardiographic abnormalities, the left ventricular end-diastolic pressure averaged 11 mm Hg, and only 7 percent ( 13/ 174) had extensive abnormalities of contraction. Mortality
Eighty-six of the 204 patients were sent to surgery, with an overall mortality during hospitalization of 8 percent ( 7I 86) . All seven deaths were related to left ventricular failure and ventricular Table 1-EclaoetiTdiop-aplaic Findi,..a, Data from Cardiac Ctllhe&eriation, and Surgical Ouecome in Patient. wicla Coronary Arterial Diaeaae •
Normal LVIDd
Data No. of patients (percent)
Abnormal LVIDd**
Normal Abnormal Normal Abnormal MV MV MV MV Closure Closure Closure Closure 102 (50)
45 (22)
27 (13)
30 (15)
Mean left ventric- . ular pressure, mm Hg (range) 10 (3-22) 11 (3-34) 10 (0-21) 23 (5-38) Left ventriculographic results, No. of patients (percentage) Normal
42 (41)
13 (29)
10 (37)
1 (3)
Segmentally abnormal
55 (54)
28 (62)
13 (48)
5 (17)
Extensively abnormal
5 (5)
4 (9)
4 (15)
24 (80)
11 (41)
9 (30)
Patients sent to surgery (percentage) 42 (41)
24 (53)
Operative mortality, percent (No. of 0 patients)
4 (1/24)
0
67 (6/9)
*Total of 204 patients with coronary artery disease, 86 of whom underwent surgery. LVIDd, End-diastolic left ventricular internal dimension related to body surface area; and MV, mitral valve. **Increased above 3.2 cm/sq m.
M-MODE ECHOCARDIOGRAPHY 183
arrhythmias. Two patients had postmortem examinations, and in each case the bypass grafts were found to be patent. Echocardiographic Findings and Mortality. Only the group of patients with both an increased left ventricular size and abnormal mitral valve closure had a significantly higher mortality. Nine of the 86 surgical patients had this finding, and six of the nine ( 67 percent) died. In comparison, the mortality was 1 percent ( 1/77) for the patients without both echocardiographic findings (P < 0.001 ). Mortality Related to Data from Cardiac Catheterization and Clinical Findings. The presence of extensive abnormalities of contraction by left ventriculographic studies was significantly ( P < O.
Echocardiograpbic left ventricular size and closure time of the mitral valve were measured in 204 consecutive patients having cardiac catheterization and significant coronary artery disease to determine if these measurements could assess the extent of left ventricular dysfunction and predict surgical mortality for those patients treated surgically. Among 30 patients having both an echocardiographically increased left ventricular internal dimension at the end of diastole and a prolonged time of mitral valve closure, left ventriculographic studies showed greater than 40 percent abnormality of wall motion in 24 patients (80 percent), and the resting left ventricular end-diastoUc pressure averaged 23 mm Hg. Of the remaining 174 patients, only 13 (7 percent)
had greater than 40 percent abnormality of wall motion, and the left ventricular end-diastoUc pressure averaged 11 mm Hg. Eighty-six of the 204 patients received surgical therapy. Mortality during hospitalization for those surgical patients with both echocardiographic findings was 67 percent (6/9) compared to 1 percent (1177) for those without both findings (P < 0.001). The combination of an echocardiographkally increased left ventricular diastoUc dimension together with a prolonged mitral valve closure (1) correlates with extensive abnormalities of wall motion and elevated left ventricular enddiastoUc pressure at cardiac catheterization, and (2) is associated with an increased surgical risk.
previous studies have shown that mortality during hospitalization following surgery for coronary artery disease is closely related to the preoperative state of ventricular function. 1•7 Elevated left ventricular end-diastolic pressure, 5-8 an abnormal pattern of contraction, 6 a decreased contractile state (as measured by the ejection fraction), 9 and congestive heart failure 8•10- 12 have all been demonstrated to increase the surgical risk; and patients are often rejected as surgical candidates when studies by cardiac catheterization reveal such abnormalities. 4 •13•14 The purpose of this investigation was to evaluate the clinical usefulness of M-mode echocardiographic studies in assessing the extent of left ventricular dysfunction and identifying high-risk surgical patients.
MATERIALS AND METHODS
Two hundred four consecutive patients with significant coronary artery disease ( 75 percent or greater narrowing of at least one coronary artery) were included in this study. For the purpose of this study, an adequate echocardiograrn was defined as one from which both the left ventricular diastolic internal dimension and the closure time of the mitral valve could be measured. Six patients were excluded due to inadequate echocardiograms. There were 172 men and 32 women. Ages ranged from 30 to 67 years, with a mean of 51 years. Of the total group, 103 patients (50 percent) had a history of prior myocardial infarction. None of the patients had undergone surgery previously for coronary artery disease or its complications.
°From the Krannert Institute of Cardiology the Department of Medicine, Indiana University Schoof of Medicine, and the Veterans Administration Haspital, Indianapolis. Supported in part by the Herman C. Krannert Fund; by grants HL-06308, HL-05363, and HL-07182 from the National Heart and Lung Institute; by the American Heart Association, Indiana Affiliate; and by the Veterans Administration. • • Associate Professor of Medicine. tAssistant Professor of Cardiovascular Research. · !Professor of Medicine. Manuscript received August 19; revision accepted December3. Reprint requests: Dr. C01'fla, Indiana University School of Medicine, Indianapolis 46202
All patients were examined with an echocardiograph (Smith-Kline) having a repetition rate of 1,000 pulses per second and utilizing a 2.25 MHz transducer with a 12 mm crystal collimated to 7.5 em. All echocardiograms were obtained on the day prior to cardiac catheterization and were recorded on either a multichannel strip-chart recorder ( Electronics for Medicine) or a portable strip-chart recorder ( Honeywell 1856). A simultaneous electrocardiographic monitoring lead was recorded on each tracing. The echocardiographic left ventricular measurements were made from recordings taken from the fourth or fifth intercostal space. The left ventricular internal dimension at the end of diastole was taken at the peak of the R wave on the electrocardiogram
CHEST, 72: 2, AUGUST, 1977
Clinical Data
Echocardiograms
M-MODE ECHOCARDIOGRAPHY 181
at or below the level of the posterior leaHet of the mitral valve ( Fig 1 ) . This echocardiographic location has been found to best reflect left septal and posterior left ventricular endocardial echoes. 15 The peak of the R wave, which has been shown to correspond to the mechanical onset of left ventricular contraction in normal patients, 1 6 was used to determine the end of diastole. This dimension was divided by the body surface area to obtain an index of the end-diastolic left ventricular internal dimension. The normal value of this index in our laboratory is 3.2 cm/sq m or less. The period of mitral valve closure ( AC) was measured from the peak of the A wave on the echocardiogram of the mitral valve to the point where the echoes from the anterior and posterior mitral leaflets met. Abnormal mitral valve closure was defined as an electrocardiographic P-R interval minus the echocardiographic AC interval (PR-AC) of 0.06 second or less ( Fig 2) . Cardiac Catheterization
AU patients underwent cardiac catheterization, including selective coronary cineangiographic and left ventriculographic studies, for the evaluation of chest pain or the feasibility of surgical therapy. Left ventricular end-diastolic pressure was measured prior to cineangiographic study. The left ventricular angiographic studies were performed in the right anterior oblique projection. Assessment of the pattern of ventricular contraction was done without knowledge of the echocardio-
NORMAL FIGURE 2. Echocardiograms of mitral valve, showing normal and prolonged mitral valve closure time. Mitral valve closure is normal when electrocardiographic P-R interval minus mitral valve A-C interval exceeds 0.06 second. graphic findings. The ventriculogram was divided into five segments, as follows: anterobasal, anterolateral, apical, diaphragmatic, and posterobasal. 17 Each of the five segments was evaluated and classifled as either normal or abnormal. A segment was called abnormal if motion was reduced (amplitude less than normal), absent, dyskinetic (paradoxical), or aneurysmal (bulging with sharply defined margins of the indicated segment) .1r Based on the sum of abnormally contracting segments, the ventriculogram was classified into one of the following three categories: ( 1 ) normal (zero abnormal segments) ; (2) segmentally abnormal, ie, with one or two segments being abnormal ( 40 percent or loss of the left ventricular perimeter); or ( 3) extensively abnormal, with three or more zones being abnormal ( greater than 40 percent of the perimeter). Surgical Group
FIGURE 1. Left ventriCular echocardiogram, showing where left ventricular internal dimension at end of diastole ( LVIDd) was measured between left septal ( LS) and posterior endocardial ( EN ) echoes.
182 CORYA ET AL
Eighty-six of the 204 patients subsequently underwent surgery using cardiopulmonary bypass and moderate hypothermia (29•c to 32•c [84.2°F to 89.6.F]). Twenty-three patients had coronary artery bypass grafting of a single vessel; 33 patients had double-vessel bypass; 16 patients
CHEST, 72: 2, AUGUST, 1977
had triple-vessel bypass; four patients had single-vessel bypass with myocardial resection; four patients had doublevessel bypass with myocardial resection; and six patients had myocardial resection only. Of the total 149 bypass grafts, the saphenous vein was used for 131 and the internal mammary artery was used for 18. Gas endarterectomy was included in the surgery in three patients.
Statistical Analysis Student's t-test was used to analyze the difference between groups for means of left ventricular end-diastolic pressure. Chi-square analysis was used to determine if a relationship existed between the echocardiographic measurements of left ventricular size and mitral valve closure and either ( 1 ) the left ventricular end-diastolic pressures and wall motion as assessed by cardiac catheterization or ( 2) mortality during hospitalization for those patients subsequently undergoing surgery. In addition, chi-square analysis was utilized to determine if there was a relationship between surgical mortality and ( 1 ) the history of myocardial infarction, ( 2) a left ventricular end-diastolic pressure ~ 20 mm Hg, ( 3) the extent of abnormal contraction by ventriculographic studies, ( 4) the number of vessels bypassed, and ( 5) myocardial resection. Mortality during hospitalization included all patients who died between induction of anesthesia and discharge from the hospital. REsULTS
Echocardiographic Data
Both the left ventricular dimension and Closure time of the mitral valve were normal in 102 of the 204 patients. Of the remaining 102 patients, 45 had a normal left ventricular dimension but abnormal mitral valve closure, 27 patients had an increased left ventricular dimension with normal mitral valve closure, and 30 patients had both abnormalities, ie, an increased left ventricular dimension and abnormal mitral valve closure. Data from Cardiac Catheterization
Of the 204 patients, 72 had single-vessel disease, 63 had two-vessel disease, and 69 had three-vessel disease. The resting left ventricular end-diastolic pressure for the 204 patients ranged from 0 to 38 mm Hg (mean, 12 mm Hg). As judged by left ventriculographic studies, the pattern of left ventricular contraction was normal in 66 patients; segmental abnormalities ( 40 percent or less) were noted in 101 patients; and extensive abnormalities (greater than 40 percent) were evident in 37 patients. Echocardiograms and Cardiac Catheterization
The echocardiographic findings and data from cardiac catheterization are summarized in Table 1. Between the groups of patients whose echocardiographic findings were either normal or showed only one of the two echocardiographic abnormalities, CHEST, 72: 2, AUGUST, 1977
there was no significant statistical difference in either the mean left ventricular end-diastolic pressure or in the ventriculographic pattern of contraction; however, both the left ventricular end-diastolic pressure and the extent of the abnormalities of contraction were significantly greater in the group of patients with both echocardiographic abnormalities ( P < 0.001). Among the 30 patients with both echocardiographic abnormalities, the left ventricular end-diastolic pressure averaged 23 mm Hg, and 80 percent (24/30) of the group had extensive abnormalities of contraction by left ventriculographic studies. Of the 174 patients without both echocardiographic abnormalities, the left ventricular end-diastolic pressure averaged 11 mm Hg, and only 7 percent ( 13/ 174) had extensive abnormalities of contraction. Mortality
Eighty-six of the 204 patients were sent to surgery, with an overall mortality during hospitalization of 8 percent ( 7I 86) . All seven deaths were related to left ventricular failure and ventricular Table 1-EclaoetiTdiop-aplaic Findi,..a, Data from Cardiac Ctllhe&eriation, and Surgical Ouecome in Patient. wicla Coronary Arterial Diaeaae •
Normal LVIDd
Data No. of patients (percent)
Abnormal LVIDd**
Normal Abnormal Normal Abnormal MV MV MV MV Closure Closure Closure Closure 102 (50)
45 (22)
27 (13)
30 (15)
Mean left ventric- . ular pressure, mm Hg (range) 10 (3-22) 11 (3-34) 10 (0-21) 23 (5-38) Left ventriculographic results, No. of patients (percentage) Normal
42 (41)
13 (29)
10 (37)
1 (3)
Segmentally abnormal
55 (54)
28 (62)
13 (48)
5 (17)
Extensively abnormal
5 (5)
4 (9)
4 (15)
24 (80)
11 (41)
9 (30)
Patients sent to surgery (percentage) 42 (41)
24 (53)
Operative mortality, percent (No. of 0 patients)
4 (1/24)
0
67 (6/9)
*Total of 204 patients with coronary artery disease, 86 of whom underwent surgery. LVIDd, End-diastolic left ventricular internal dimension related to body surface area; and MV, mitral valve. **Increased above 3.2 cm/sq m.
M-MODE ECHOCARDIOGRAPHY 183
arrhythmias. Two patients had postmortem examinations, and in each case the bypass grafts were found to be patent. Echocardiographic Findings and Mortality. Only the group of patients with both an increased left ventricular size and abnormal mitral valve closure had a significantly higher mortality. Nine of the 86 surgical patients had this finding, and six of the nine ( 67 percent) died. In comparison, the mortality was 1 percent ( 1/77) for the patients without both echocardiographic findings (P < 0.001 ). Mortality Related to Data from Cardiac Catheterization and Clinical Findings. The presence of extensive abnormalities of contraction by left ventriculographic studies was significantly ( P < O.
