A Temporary Catheter-Tip Aortic Valve: Hernodynamic Effects on Experimental Acute Aortic Insuffiaency S. J. Phillips, M.D., M. Ciborski, M.D., P. S. Freed, M.S., 1’. N. Cascade, M.D., a n d D. Jaron, Ph.D. ABSTRACT A catheter-mounted polyurethane cusp was designed to act as a temporary prosthetic aortic valve in the ascending aorta. Acute aortic insufficiency was created in 15 dogs by transventriculartearing of the two aortic valve leaflets with a wire hook. Hemodynamicvariables were measured during aortic insufficiency and with the prosthetic valve in place. Comparison of the values showed that the prosthesis functioned as a competent aortic valve. Aortic diastolic pressure increased by 62 f 42%, pulse pressure was lowered by 44 +- 9%, and left ventricular enddiastolic pressure decreased by 45 L 18%. Neither cardiac output, coronary blood flow, nor peak systolic pressure was significantly altered. The observed hemodynamic improvement and the simplicity of the design and application suggest that the prosthetic aortic valve may be applicable in the temporary treatment of decompensated aortic insufficiency.
newly designed catheter-tip aortic valve on acute aortic insufficiency.
Materials and Methods
A segmented polyurethane cusp mounted on a catheter (Fig 1)was designed to act as a temporary prosthetic aortic valve. The cusp is approximately 0.25 mm thick, 35 mm deep, and 22 mm in diameter at its widest point. The cusp is mounted 1 cm from the end of a polyurethane catheter 4 mm in diameter and 60 cm in length. The size of the cusp should be slightly smaller than the aortic lumen so that coronary flow is not obstructed during diastole. A small segment of the free edge of the cusp is fixed to the catheter to prevent inversion of the cusp during diastole (Fig 2). The catheter tip contains side-holes for monitoring arterial pressure during passage of Decompensated aortic insufficiency is a life- the valve to the aortic root through a carotid threatening situation often requiring emergency artery. Fifteen dogs, each weighing 30 kg, were anesaortic valve replacement. Operative procedures thetized with sodium pentobarbital (50 mg per not utilizing cardiopulmonary bypass such as kilogram of body weight) and placed on a Bird implantation of a valve in the descending thoracic aorta are associated with the morbidity Mark VII respirator. Thoracotomy was perand mortality of emergency thoracotomy and are formed through the fourth left intercostal space. Electromagnetic flow probes were placed not too effective hemodynamically [l, 2, 51. If hemodynamic stabilization could be around the main pulmonary artery and the left achieved in patients with decompensated aortic circumflex coronary artery. Large-bore catheters insufficiency prior to operation, the surgical were inserted into the left ventricle by direct mortality might be substantially reduced. puncture and into the ascending aorta through a Moulopoulos and associates 141 described a femoral arteriotomy. Cardiac output was calcucatheter-mounted, umbrella-shaped valve that lated from the pulmonary artery flow curves. Transventricular avulsion with a wire hook of is hemodynamically effective for the treatment at least two aortic valve leaflets created grade 4+ of experimental aortic insufficiency when aortic insufficiency. The catheter-tip aortic valve positioned in the ascending aorta. This study was passed to the level of the aortic root through describes the hemodynamic effects in dogs of a a carotid artery. Palpating the aortic root or From the Department of Surgery, Sinai Hospital of Detroit, monitoring arterial pressure through the catheDetroit, MI. ter during its passage (Fig 3) confirmed the locaSupported by US Public Health Service Grant no. HL 13737. tion of the valve. Accepted for publication July 17, 1975. Continuous recordings of central aortic presAddress reprint requests to the SurgicalResearch Laboratory, sure, left ventricular pressure, left ventricular Sinai Hospital of Detroit, 6767W OuterDr, Detroit, MI48235. 134
135 Phillips et al: Temporary Catheter-Tip Aortic Valve
end-diastolic pressure, left circumflex coronary artery blood flow, and main pulmonary artery blood flow were obtained prior to aortic insufficiency, after the creation of aortic insufficiency, and following insertion of the catheter-tip aortic valve. Each dog acted as its own control. Percent changes in these variables between aortic insufficiency and with the catheter-tip aortic valve in position were calculated and their significance tested by Student's t-test for paired data.
Fig 1. Catheter-mounted, single-cusp aortic valve.
Fig2 Close-up of catheter-tip aortic valve. A point on thefree edge o f t h e cusp isfixed to the catheter to prevent the valve f r o m inverting during diastole. 200
,
Results The prosthesis functioned as a competent aortic valve as evidenced by an increase in aortic diastolic pressure of 62 k 42O/0, a reduction in pulse pressure of 44 f go/', and a reduction of left ventricular end-diastolic pressure by 45 f 18%. The p values for these changes were less than 0.01. The Table summarizes the hemodynamic data. Figure 4 represents typical flow and pressure tracings with aortic insufficiency as compared to corrected aortic insufficiency with the prosthetic valve. Note the favorable reductions in aortic pulse pressure and left ventricular end-diastolic pressure. In our experimental model of aortic insufficiency the predominant [ phase of coronary artery blood flow occurs during systole. After insertion of the prosthetic valve, most of the coronary artery blood flow occurs during the diastolic phase of the cardiac cycle.
-1, 'I*
loo
0
Fig3. Centralaorticpressure (CAP) in the ascending aorta and pressure measured at the tip of the catheter indicate value location during implantation. A drop in diastolic pressure to 0 indicates entrance of the catheter tip into the vestricle.
Comment Experiments with the catheter-tip aortic valve indicate its hemodynamic effectiveness and
136 The Annals of Thoracic Surgery
Vol 21 No 2 February 1976
Comparison of Hemodynamic Variables before and after Correction of Aortic Insufficiency with the Catheter-Mounted Aortic Valve Measurement
70 Change
Standard Deviation
P
Aortic diastolic pressure Pulse pressure Left ventricular end-diastolic pressure Peak systolic pressure Cardiac output Coronary blood flow
+62 -44 -45 - 7 - 2 + 4
42 9 18 20 25 31
newly designed catheter-tip aortic valve on acute aortic insufficiency.
Materials and Methods
A segmented polyurethane cusp mounted on a catheter (Fig 1)was designed to act as a temporary prosthetic aortic valve. The cusp is approximately 0.25 mm thick, 35 mm deep, and 22 mm in diameter at its widest point. The cusp is mounted 1 cm from the end of a polyurethane catheter 4 mm in diameter and 60 cm in length. The size of the cusp should be slightly smaller than the aortic lumen so that coronary flow is not obstructed during diastole. A small segment of the free edge of the cusp is fixed to the catheter to prevent inversion of the cusp during diastole (Fig 2). The catheter tip contains side-holes for monitoring arterial pressure during passage of Decompensated aortic insufficiency is a life- the valve to the aortic root through a carotid threatening situation often requiring emergency artery. Fifteen dogs, each weighing 30 kg, were anesaortic valve replacement. Operative procedures thetized with sodium pentobarbital (50 mg per not utilizing cardiopulmonary bypass such as kilogram of body weight) and placed on a Bird implantation of a valve in the descending thoracic aorta are associated with the morbidity Mark VII respirator. Thoracotomy was perand mortality of emergency thoracotomy and are formed through the fourth left intercostal space. Electromagnetic flow probes were placed not too effective hemodynamically [l, 2, 51. If hemodynamic stabilization could be around the main pulmonary artery and the left achieved in patients with decompensated aortic circumflex coronary artery. Large-bore catheters insufficiency prior to operation, the surgical were inserted into the left ventricle by direct mortality might be substantially reduced. puncture and into the ascending aorta through a Moulopoulos and associates 141 described a femoral arteriotomy. Cardiac output was calcucatheter-mounted, umbrella-shaped valve that lated from the pulmonary artery flow curves. Transventricular avulsion with a wire hook of is hemodynamically effective for the treatment at least two aortic valve leaflets created grade 4+ of experimental aortic insufficiency when aortic insufficiency. The catheter-tip aortic valve positioned in the ascending aorta. This study was passed to the level of the aortic root through describes the hemodynamic effects in dogs of a a carotid artery. Palpating the aortic root or From the Department of Surgery, Sinai Hospital of Detroit, monitoring arterial pressure through the catheDetroit, MI. ter during its passage (Fig 3) confirmed the locaSupported by US Public Health Service Grant no. HL 13737. tion of the valve. Accepted for publication July 17, 1975. Continuous recordings of central aortic presAddress reprint requests to the SurgicalResearch Laboratory, sure, left ventricular pressure, left ventricular Sinai Hospital of Detroit, 6767W OuterDr, Detroit, MI48235. 134
135 Phillips et al: Temporary Catheter-Tip Aortic Valve
end-diastolic pressure, left circumflex coronary artery blood flow, and main pulmonary artery blood flow were obtained prior to aortic insufficiency, after the creation of aortic insufficiency, and following insertion of the catheter-tip aortic valve. Each dog acted as its own control. Percent changes in these variables between aortic insufficiency and with the catheter-tip aortic valve in position were calculated and their significance tested by Student's t-test for paired data.
Fig 1. Catheter-mounted, single-cusp aortic valve.
Fig2 Close-up of catheter-tip aortic valve. A point on thefree edge o f t h e cusp isfixed to the catheter to prevent the valve f r o m inverting during diastole. 200
,
Results The prosthesis functioned as a competent aortic valve as evidenced by an increase in aortic diastolic pressure of 62 k 42O/0, a reduction in pulse pressure of 44 f go/', and a reduction of left ventricular end-diastolic pressure by 45 f 18%. The p values for these changes were less than 0.01. The Table summarizes the hemodynamic data. Figure 4 represents typical flow and pressure tracings with aortic insufficiency as compared to corrected aortic insufficiency with the prosthetic valve. Note the favorable reductions in aortic pulse pressure and left ventricular end-diastolic pressure. In our experimental model of aortic insufficiency the predominant [ phase of coronary artery blood flow occurs during systole. After insertion of the prosthetic valve, most of the coronary artery blood flow occurs during the diastolic phase of the cardiac cycle.
-1, 'I*
loo
0
Fig3. Centralaorticpressure (CAP) in the ascending aorta and pressure measured at the tip of the catheter indicate value location during implantation. A drop in diastolic pressure to 0 indicates entrance of the catheter tip into the vestricle.
Comment Experiments with the catheter-tip aortic valve indicate its hemodynamic effectiveness and
136 The Annals of Thoracic Surgery
Vol 21 No 2 February 1976
Comparison of Hemodynamic Variables before and after Correction of Aortic Insufficiency with the Catheter-Mounted Aortic Valve Measurement
70 Change
Standard Deviation
P
Aortic diastolic pressure Pulse pressure Left ventricular end-diastolic pressure Peak systolic pressure Cardiac output Coronary blood flow
+62 -44 -45 - 7 - 2 + 4
42 9 18 20 25 31
