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Clinical and hemodynamic evaluation of the 19-mm Carpentier-Edwards supraannular aortic valve
Clinical and Hemodynamic Evaluation of the 19-mm Carpentier-Edwards Supraannular Aortic Valve Panny Kallis, FRCS, James F. Sneddon, MRCP, Iain A. Simpson, MRCP, Anthony Fung, FRCS, John R. Pepper, FRCS, and E. E. JoKn Smith, FRCS Departments of Cardiothoracic Surgery and Cardiology, St. George's Hospital, London, England
The clinical and hemodynamic performance of the 19-mm Carpentier-Edwards supraannular aortic valve is largely unknown compared with that of the larger valves. Over 4 years we implanted the 19-mm CarpentierEdwards supraannular aortic valve into 21 patients (20 female) with a mean age of 75 & 1.2 years (range, 59 to 86 years) and a mean body surface area of 1.6 f. 0.03 m2 (range, 1.3 to 1.7 m2). There were four deaths, one operative and three late noncardiac deaths. Follow-up of the 17 survivors for a mean of 20 f. 3.1 months (range, 2 to 42 months) demonstrated symptomatic improvement in all 17 (all are now in New York Heart Association functional class I or 11). There were no valve-related complications and no patient required long-term anticoagulation. Doppler echocardiographic studies were used to assess the in vivo hemodynamic profile of the valve.
Mean postoperative aortic valve gradient was 34.1 & 2.7 mm Hg (range, 19 to 52 mm Hg). Functional valve orifice area was 1.1 f. 0.09 cm2 (range, 0.6 to 1.8 cm2). Mean cardiac output was 3.92 f. 0.17 Llmin (range, 3.2 to 5.1 L/min) with a mean cardiac index of 2.5 2 0.11 L min-l * m-' (range, 2.1 to 3.2 L * min-l * m-'). In conclusion, we have demonstrated that aortic valve replacement with the 19-mm Carpentier-Edwards supraannular aortic valve has a low operative mortality and offers major clinical benefits despite moderate transprosthetic gradients. This approach provides an alternative management strategy in elderly patients who would otherwise require low-profile mechanical valves or aortic root enlargement.
V
coagulation is undesirable and aortic root enlargement might increase the morbidity and mortality [l].For these reasons the 19-mm CE-SAV was our bioprosthetic valve of choice for this population between 1986 and 1991. This report of clinical follow-up and postoperative twodimensional Doppler echocardiographic assessment defines the normal in vivo hemodynamic profile of the 19-mm CE-SAV and identifies the group of patients in whom a small valve can provide an acceptable clinical result.
alves larger than 21 mm have good hemodynamic performance, unlike many of the 19-mm valves. The 19-mm Bjork-Shiley [l,21 and the 19-mm St. Jude Medical [2, 31 valves have low transprosthetic gradients but require long-term anticoagulation. Of the 19-mm tissue valves only the Ionescu-Shiley pericardial valve has been shown to have adequate hemodynamics, but this has been withdrawn because of unacceptable failure rates [4, 51. The in vivo hemodynamic performance of the 19-mm Carpentier-Edwards supraannular porcine aortic valve (CE-SAV) (Baxter-Edwards, Irvine, CA) is largely unknown. There has been reluctance to implant this valve because of the potential adverse hemodynamic profile associated with the use of such small diameters. Aortic valve replacement (AVR) with a 19-mm valve in a patient with body surface area larger than 1.7 m2 and good cardiac output can result in high transvalvular gradients (valve-patient mismatch) and prevent clinical improvement of the patient [6]. Surgeons have therefore tended to either use a low-profile mechanical valve or enlarge the aortic annulus. The small aortic root, however, is frequently encountered in elderly patients, mainly women, in whom antiAccepted for publication April 13, 1992 Address reprint requests to Mr Kallis, Department of Cardiothoracic Surgery, Harefield Hospital, Harefield, Middlesex UB9 6JH, England.
0 1992 by The Society of Thoracic Surgeons
-
(Ann Thorac Surg 1992;54:1182-5)
Material and Methods Patient Population The hernodynamic profile and clinical outcome of 21 consecutive patients who underwent AVR with the 19-mm CE-SAV were reviewed. Demographic data showed 1 male and 20 female patients with a mean age of 75 & 1.2 years (range, 59 to 86 years). The mean body surface area was 1.6 & 0.03 m2, with a range of 1.3 to 1.7 m2. The main presenting symptoms were shortness of breath on exertion (17), angina (9), syncope (4), and pulmonary edema (l),with 10 patients having more than one symptom. Twenty patients underwent preoperative cardiac catheterization with an average aortic gradient of 96 & 6.4 mm Hg (range, 50 to 140 mm Hg). One patient, who presented with pulmonary edema, had the diagnosis 0003-4975/92/$5.00
KALLIS ET AL 19-mm CARPENTIER-EDWARDS SUPRAANNULAR VALVE
Ann Thorac Surg 1992;54:1182-5
of aortic stenosis confirmed on the basis of echocardiography alone, as she required an emergency operation. One patient had undergone an unsuccessful balloon valvuloplasty. Thirteen of the procedures were classified as urgent, seven as elective, and one as an emergency. Four of the patients were classified as being in New York Heart Association (NYHA) functional class IV, 12 in class 111, and 5 in class I1 preoperatively. Isolated AVR was performed in 15 patients, AVR and concomitant coronary revascularization in 5 patients, and AVR and mitral valve replacement in 1 patient.
Operative Technique All patients received prophylactic intravenous cefuroxime at the time of induction of anesthesia, and this antibiotic regimen was continued for 48 hours postoperatively. Venous drainage was achieved with a two-stage cannula (Stockert-Shiley, Irvine, CA); a membrane oxygenator was used, and the return was into the distal ascending aorta (26F to 28F Wessex cannula). Cardiopulmonary bypass was established with systemic hypothermia to 25°C with flow rates of 1.6 to 2.4 L min-’ * m-* and a mean arterial pressure of 60 mm Hg. A vent was placed through the apex of the left ventricle. Multidose cold crystalloid cardioplegia (St. Thomas’ solution) was infused directly into the coronary ostia. Topical cooling was also used (4°C Hartmann’s solution). After excision of the valve, the aortic annulus was debrided of residual calcium and the 19-mm CE-SAV was placed in the supraannular position with interrupted sutures of 2-0 Ticron (Davis & Geck, Gosport, Hampshire, England). No anticoagulants were used postoperatively in patients who underwent isolated AVR, but aspirin was used in patients who underwent concomitant coronary revascularization. Warfarin was used in the patient who underwent additional mitral valve replacement, but this was discontinued after 2 months.
-
Clinical Follow-up Postoperative complications were determined from patient records. Fifteen of the 17 survivors were reviewed in the outpatient clinic at the time of the study for recurrent symptoms, NYHA functional status, medications being taken, and valve-related complications. The remaining 2 survivors who were unable to attend because of distance were assessed over the telephone. The causes of late deaths were determined from the patient records and postmortem reports.
Echocardiographic Follow-up Two-dimensional echocardiography and Doppler ultrasound were performed (parasternal and apical views) using a Vingmed CFM 750 with a 3.5-MHz transducer. The maximum velocity (V) through the aortic prosthesis measured by continuous-wave Doppler ultrasound was used to estimate the aortic valve gradient at rest using the modified Bernoulli equation [7]: maximum instantaneous gradient = 4V2. Two-dimensional echocardiography was used to mea-
1183
sure the diameter of the left ventricular outflow tract (LVOT) from the parasternal long-axis view, and pulsedwave Doppler ultrasound from the apex was used to determine the left ventricular outflow tract velocity. Aortic valve (AV) area was then calculated using the equation of continuity [8] such that: area(LV0T) x velocity(LV0T) = area(AV) x velocity(AV).The cardiac output at rest was calculated using the formula [9]: cardiac output = time velocity integral x AV area x heart rate.
Statistical Analysis All data are expressed as the mean 5 the standard error of the mean using the statistical package Clinstat.
Results Early Morbidity and Mortality There was one operative death (4.8%) in a 79-year-old woman (NYHA class IV) who underwent AVR and triple coronary artery bypass grafting. She also had moderate mitral regurgitation, but the mitral valve was not replaced. One patient, who had pulmonary edema preoperatively, required the use of inotropic agents and an intraaortic balloon to come off bypass. Three patients (14%)underwent resternotomy for bleeding secondary to coagulopathy, and acute renal failure developed in 1 patient (4.8%).Two patients (9.5%)required placement of a permanent pacemaker system because of complete heart block postoperatively. One patient underwent a tracheostomy for prolonged ventilation.
Late Clinical Follow-up There were three late deaths: at 2 months due to a gangrenous leg in an 80-year-old diabetic woman, at 15 months due to a blocked tracheostomy, and at 24 months due to hepatic metastases. All 17 of the survivors were traced (by April 1991). Mean follow-up was 20 5 3.1 months (range, 2 to 42 months). Fifteen of these patients were interviewed and examined, whereas 2 were interviewed over the telephone because of distance. There were no valve-related complications such as thromboembolic events, prosthetic endocarditis, hemolysis, or aortic insufficiency requiring reoperation. No patient required long-term anticoagulation, and none of them suffered any gastrointestinal hemorrhage. All the survivors were on less medication than preoperatively, and they all demonstrated excellent clinical improvement according to the NYHA functional classification (Fig 1).Two (11.8%)were in class IV, 11 (64.7%)in class III, and 4 (23.5%)in class I1 preoperatively, whereas 7 (41.2%) were in class I1 and 10 (58.8%) in class I postoperatively. Every patient had improved NYHA functional status.
Echocardiographic Follow-up Fifteen of the 17 patients had postoperative echocardiograms at the time of the study (average time, 20 2 3.1 months; range, 2 to 42 months). In 1 patient it was impossible to obtain an adequate Doppler signal to calcu-
1184
KALLIS ET AL 19-mmCARPENTIER-EDWARDS SUPRAANNULAR VALVE
NYHA Class
Preor>
Postoo
I I1 111 IV Fig 1 . Comparison of the Nao York Heart Association (NYHA) functional status of the 17 survivors preoperatively and postoperatively (time of follow-up).
late the transprosthetic gradient and valve area. The two-dimensional echocardiogram demonstrated hypertrophy of the left ventricle and good left ventricular function in the other 14 patients. There was no evidence of structural failure of any of the prostheses, but there was a minor paraprosthetic leak in 1 patient. This was not significant hemodynamically, however, as the patient was in NYHA functional class I. The mean cardiac output at rest was 3.92 ? 0.17 L/min (range, 3.2 to 5.1 L/min) with a cardiac index of 2.5 f 0.11 L min-’ * m-’ (range, 2.1 to 3.2 L * min-’ m-’), which is at the lower end of the normal range for 75-year-olds. The average maximum instantaneous gradient at rest was 34.1 k 2.7 mm Hg (range, 19 to 52 mm Hg). The mean effective valve area was 1.1 It 0.09 cm2 (range, 0.6 to 1.8 cm2).
-
Comment Aortic valve replacement in the small aortic root presents a special challenge to the surgeon in regard to both operative technique and selection of prosthesis. These patients are predominantly older women with small body surface areas and severe calcific aortic stenosis, as confirmed by our patient population. When choosing a prosthesis for these patients three main factors have to be considered. First, such patients are unable to withstand difficult and prolonged procedures, which carry a high mortality and morbidity [l,101. Second, the hemodynamic performance of the prosthesis chosen must be adequate to avoid valve prosthesispatient mismatch, which would prevent clinical improvement of the patient [6]. Third, use of anticoagulants in elderly patients should be avoided if possible. Enlargmg the aortic annulus, either with an incision through the annulus into the anterior mitral leaflet [lo] or with a more extensive aortoventriculoplasty (Konno procedure) [ll],is poorly tolerated in elderly patients with calcified aortic roots [12]. The small Starr-Edwards valves (7-A and 8-A) have unacceptable transprosthetic gradients and are associated with an increased perioperative mortality [13]. Catheterization data of patients with 19-mm St. Jude valves
showed a peak-to-peak gradient of 16 mm Hg and functional orifice area of 1.22 cm2 [3]. Echocardiographic assessment of the same valve showed a maximum instantaneous gradient of 38 mm Hg [14]. Catheterization of patients with a 19-mm Bjork-Shiley valve revealed a functional orifice area of 1.06 cm2 and a peak systolic gradient of 16 mm Hg [l]. Major bleeding complications occurred in 13% of these patients, and minor bleeding complications developed in a further 13% [I]. The main advantage of tissue valves is the avoidance of anticoagulants, but structural failure still remains a problem. Bojar and colleagues [4]reported a good hemodynamic profile of the 19-mm Ionescu-Shiley pericardial valve echocardiographically. The maximum instantaneous gradient was 17 mm Hg and the effective orifice area 1.2 cm2. They also confirmed low operative mortality and demonstrated excellent clinical improvement, but the valve was withdrawn from the market in 1987 because of unacceptable structural failure rates. The 19-mm modified Hancock valve has a peak systolic gradient of 22 mm Hg and a functional orifice area of 1.1 cm2 [2]. The standard Carpentier-Edwards prosthesis has a smaller width of the prosthetic base and an asymmetric annulus, which provides a more effective orifice to external diameter ratio. In vivo hemodynamic data of the 19-mm valve, however, are scarce. Catheterization data in 3 patients revealed a peak systolic gradient of 33 mm Hg and a functional orifice area of 1.1 cm2 [15]. Carpentier and colleagues [161 described the design and preservation techniques of the CE-SAV in 1982. The prosthesis was developed to be implanted in the supraannular position, rather than within the annulus, to provide an orifice of the same diameter as the patient’s annulus. Such an approach attempted to reduce the transvalvular gradient across the standard 19-mm valve. The in vivo hemodynamic performance of the 19-mm CE-SAV is largely unknown because of fear of unacceptable transprosthetic gradients and failure of clinical improvement of the patient. This study, however, demonstrates that AVR with a 19-mm CE-SAV leads to major symptomatic improvement of the patients despite moderate transprosthetic gradients. As seen in the scattergram in Figure 2 there was no correlation between transprosthetic gradient and body surface area. The higher gradients are therefore more likely to be due to variation of cardiac output than to valve prosthesis-patient mismatch. Foster and colleagues [2] also found that there was no correlation of transvalvular gradient at rest with the clinical status of the patients at follow-up. Continuouswave Doppler ultrasound estimates the maximum instantaneous gradient rather than the peak-to-peak gradient as measured at cardiac catheterization. The more physiological Doppler-defined gradient, therefore, may be as much as 20 mm Hg higher than the peak-to-peak gradient [17, 181. Jamieson and colleagues [19] in 1988 reported their overall clinical results in 1,167 patients in whom they implanted CE-SAVs of all sizes. The freedom from structural deterioration at 4 years was 99% and from all
KALLIS ET AL 19-mm CARPENTIER-EDWARDS SUPRAANNULAR VALVE
Ann Thorac Surg 1992;- 11825
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Fig 2. Scattergram of maximum instantaneous gradient and body surface area (BSA), showing no correlation (r = 0.15).
valve-related complications, 86%. They therefore concluded that the CE-SAV offers excellent intermediate clinical results. In conclusion, this study defines the normal in vivo hemodynamic profile of the 19-mm CE-SAV. It also demonstrates that its use is associated with low operative mortality and low incidence of valve-related complications, and offers major clinical improvement despite moderate transprosthetic gradients. We believe that this approach provides an alternative management strategy in the small elderly patients who would otherwise require a low-profile mechanical valve or enlargement of the aortic annulus.
References 1. Schaff HV, Borkon AM, Hughes C, et al. Clinical and hemodynamic evaluation of the 19 mm Bjork-Shiley aortic valve prosthesis. Ann Thorac Surg 1981;3250-7. 2. Foster AH, Tracey CM, Greenberg GJ, McIntosh CL, Clark RE. Valve replacement in narrow aortic roots: serial hemodynamics and long-term clinical outcome. Ann Thorac Surg 1986;42:506-16.
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3. Wortham DC, Tri TB, Bowen TE. Hemodynamic evaluation of the St. Jude Medical valve prosthesis in the small aortic annulus. J Thorac Cardiovasc Surg 1981;81:615-20. 4. Bojar RM, Diehl JT, Moten M, et al. Clinical and hemodynamic performance of the Ionescu-Shiley valve in the small aortic root. J Thorac Cardiovasc Surg 1989;89:1087-95. 5. Revuelta JM, Duran CMG, Garcia-Rinaldi R. Performance of the Ionescu-Shiley pericardial valve in the small aortic annulus. In: Proceedings of the cardiac prosthesis symposium 111, September 1985. Montreux, Switzerland: Shiley, Inc, 1987 17-22. 6. Rahimtoola SH. The problem of valve prosthesispatient mismatch. Circulation 1978;5820-4. 7. Simpson IA, Houston AB, Sheldon CD, Hutton I, Lawrie TDV. Clinical value of Doppler echocardiography in the assessment of adults with aortic stenosis. Br Heart J 1985;53: 636-9. 8. Skjaerpe T, Hegrenaes L, Hatle L. Noninvasive estimation of valve area in patients with aortic stenosis by Doppler ultrasound and two-dimensional echocardiography. Circulation - * . 1985;72810-8. 9. Huntsman LL. Stewart DK. Barnes SR, Franklin SB, Colocousis JS, Hessel EA. Noninvasive Doppler determination of cardiac output in man. Clinical validation. Circulation 1983; 67593402. 10. Manouguian S, Seybold-EptingW. Patch enlargement of the aortic valve ring by extending the aortic incision into the anterior mitral leaflet: new operative technique. J Thorac Cardiovasc Surg 1979;78402-12. 11. Misbach GA, Turley K, LJllyot DJ, Ebert PA. Left ventricular outflow enlargement by the Konno procedure. J Thorac Cardiovasc Surg 1982;84:696-703. 12. Rastan H, Abu-Aishah N, Rastan D, et al. Results of aortoventriculoplasty in 21 consecutive patients with left ventricular outflow tract obstruction. J Thorac Cardiovasc Surg 1978;75:659-69. 13. Blank RH, Pupello DF, Bessone LN, Hamson EE, Sbar S. Method of managing the small aortic annulus during valve replacement. Ann Thorac Surg 1976;22356-61. 14. Panidis IF, Ross JR, Mintz GS. Normal and abnormal prosthetic valve function as assessed by Doppler echocardiography. J Am Coll Cardiol 1986;8:317-26. 15. Bove EL, Marvasti MA, Potts JL, et al. Rest and exercise hemodynamics following aortic valve replacement: a comparison between 19 and 21 mm Ionescu-Shiley pericardial and Carpentier-Edwards porcine valves. J Thorac Cardiovasc Surg 1985;90750-5. 16. Carpentier A, Dubost C, Lane E, et al. Continuing improvement in valvular prostheses. J Thorac Cardiovasc Surg 1982; 8327-42. 17. Cooper DM, Stewart WJ, Schiavone WA, et al. Evaluation of normal prosthetic valve function by Doppler echocardiography. Am Heart J 1987;114:576-82. 18. Reisner SA, Meltzer RS. Normal values for prosthetic valve Doppler echocardiographic parameters: a review. J Am SOC Echocardiogr 1988;1:200-10. 19. Jamieson WRE, Munro AI, Miyagishima RT. The CarpentierEdwards supraannular porcine bioprosthesis. A new generation of tissue valve with excellent intermediate clinical performance. J Thorac Cardiovasc Surg 1988;96652-66.
The clinical and hemodynamic performance of the 19-mm Carpentier-Edwards supraannular aortic valve is largely unknown compared with that of the larger valves. Over 4 years we implanted the 19-mm CarpentierEdwards supraannular aortic valve into 21 patients (20 female) with a mean age of 75 & 1.2 years (range, 59 to 86 years) and a mean body surface area of 1.6 f. 0.03 m2 (range, 1.3 to 1.7 m2). There were four deaths, one operative and three late noncardiac deaths. Follow-up of the 17 survivors for a mean of 20 f. 3.1 months (range, 2 to 42 months) demonstrated symptomatic improvement in all 17 (all are now in New York Heart Association functional class I or 11). There were no valve-related complications and no patient required long-term anticoagulation. Doppler echocardiographic studies were used to assess the in vivo hemodynamic profile of the valve.
Mean postoperative aortic valve gradient was 34.1 & 2.7 mm Hg (range, 19 to 52 mm Hg). Functional valve orifice area was 1.1 f. 0.09 cm2 (range, 0.6 to 1.8 cm2). Mean cardiac output was 3.92 f. 0.17 Llmin (range, 3.2 to 5.1 L/min) with a mean cardiac index of 2.5 2 0.11 L min-l * m-' (range, 2.1 to 3.2 L * min-l * m-'). In conclusion, we have demonstrated that aortic valve replacement with the 19-mm Carpentier-Edwards supraannular aortic valve has a low operative mortality and offers major clinical benefits despite moderate transprosthetic gradients. This approach provides an alternative management strategy in elderly patients who would otherwise require low-profile mechanical valves or aortic root enlargement.
V
coagulation is undesirable and aortic root enlargement might increase the morbidity and mortality [l].For these reasons the 19-mm CE-SAV was our bioprosthetic valve of choice for this population between 1986 and 1991. This report of clinical follow-up and postoperative twodimensional Doppler echocardiographic assessment defines the normal in vivo hemodynamic profile of the 19-mm CE-SAV and identifies the group of patients in whom a small valve can provide an acceptable clinical result.
alves larger than 21 mm have good hemodynamic performance, unlike many of the 19-mm valves. The 19-mm Bjork-Shiley [l,21 and the 19-mm St. Jude Medical [2, 31 valves have low transprosthetic gradients but require long-term anticoagulation. Of the 19-mm tissue valves only the Ionescu-Shiley pericardial valve has been shown to have adequate hemodynamics, but this has been withdrawn because of unacceptable failure rates [4, 51. The in vivo hemodynamic performance of the 19-mm Carpentier-Edwards supraannular porcine aortic valve (CE-SAV) (Baxter-Edwards, Irvine, CA) is largely unknown. There has been reluctance to implant this valve because of the potential adverse hemodynamic profile associated with the use of such small diameters. Aortic valve replacement (AVR) with a 19-mm valve in a patient with body surface area larger than 1.7 m2 and good cardiac output can result in high transvalvular gradients (valve-patient mismatch) and prevent clinical improvement of the patient [6]. Surgeons have therefore tended to either use a low-profile mechanical valve or enlarge the aortic annulus. The small aortic root, however, is frequently encountered in elderly patients, mainly women, in whom antiAccepted for publication April 13, 1992 Address reprint requests to Mr Kallis, Department of Cardiothoracic Surgery, Harefield Hospital, Harefield, Middlesex UB9 6JH, England.
0 1992 by The Society of Thoracic Surgeons
-
(Ann Thorac Surg 1992;54:1182-5)
Material and Methods Patient Population The hernodynamic profile and clinical outcome of 21 consecutive patients who underwent AVR with the 19-mm CE-SAV were reviewed. Demographic data showed 1 male and 20 female patients with a mean age of 75 & 1.2 years (range, 59 to 86 years). The mean body surface area was 1.6 & 0.03 m2, with a range of 1.3 to 1.7 m2. The main presenting symptoms were shortness of breath on exertion (17), angina (9), syncope (4), and pulmonary edema (l),with 10 patients having more than one symptom. Twenty patients underwent preoperative cardiac catheterization with an average aortic gradient of 96 & 6.4 mm Hg (range, 50 to 140 mm Hg). One patient, who presented with pulmonary edema, had the diagnosis 0003-4975/92/$5.00
KALLIS ET AL 19-mm CARPENTIER-EDWARDS SUPRAANNULAR VALVE
Ann Thorac Surg 1992;54:1182-5
of aortic stenosis confirmed on the basis of echocardiography alone, as she required an emergency operation. One patient had undergone an unsuccessful balloon valvuloplasty. Thirteen of the procedures were classified as urgent, seven as elective, and one as an emergency. Four of the patients were classified as being in New York Heart Association (NYHA) functional class IV, 12 in class 111, and 5 in class I1 preoperatively. Isolated AVR was performed in 15 patients, AVR and concomitant coronary revascularization in 5 patients, and AVR and mitral valve replacement in 1 patient.
Operative Technique All patients received prophylactic intravenous cefuroxime at the time of induction of anesthesia, and this antibiotic regimen was continued for 48 hours postoperatively. Venous drainage was achieved with a two-stage cannula (Stockert-Shiley, Irvine, CA); a membrane oxygenator was used, and the return was into the distal ascending aorta (26F to 28F Wessex cannula). Cardiopulmonary bypass was established with systemic hypothermia to 25°C with flow rates of 1.6 to 2.4 L min-’ * m-* and a mean arterial pressure of 60 mm Hg. A vent was placed through the apex of the left ventricle. Multidose cold crystalloid cardioplegia (St. Thomas’ solution) was infused directly into the coronary ostia. Topical cooling was also used (4°C Hartmann’s solution). After excision of the valve, the aortic annulus was debrided of residual calcium and the 19-mm CE-SAV was placed in the supraannular position with interrupted sutures of 2-0 Ticron (Davis & Geck, Gosport, Hampshire, England). No anticoagulants were used postoperatively in patients who underwent isolated AVR, but aspirin was used in patients who underwent concomitant coronary revascularization. Warfarin was used in the patient who underwent additional mitral valve replacement, but this was discontinued after 2 months.
-
Clinical Follow-up Postoperative complications were determined from patient records. Fifteen of the 17 survivors were reviewed in the outpatient clinic at the time of the study for recurrent symptoms, NYHA functional status, medications being taken, and valve-related complications. The remaining 2 survivors who were unable to attend because of distance were assessed over the telephone. The causes of late deaths were determined from the patient records and postmortem reports.
Echocardiographic Follow-up Two-dimensional echocardiography and Doppler ultrasound were performed (parasternal and apical views) using a Vingmed CFM 750 with a 3.5-MHz transducer. The maximum velocity (V) through the aortic prosthesis measured by continuous-wave Doppler ultrasound was used to estimate the aortic valve gradient at rest using the modified Bernoulli equation [7]: maximum instantaneous gradient = 4V2. Two-dimensional echocardiography was used to mea-
1183
sure the diameter of the left ventricular outflow tract (LVOT) from the parasternal long-axis view, and pulsedwave Doppler ultrasound from the apex was used to determine the left ventricular outflow tract velocity. Aortic valve (AV) area was then calculated using the equation of continuity [8] such that: area(LV0T) x velocity(LV0T) = area(AV) x velocity(AV).The cardiac output at rest was calculated using the formula [9]: cardiac output = time velocity integral x AV area x heart rate.
Statistical Analysis All data are expressed as the mean 5 the standard error of the mean using the statistical package Clinstat.
Results Early Morbidity and Mortality There was one operative death (4.8%) in a 79-year-old woman (NYHA class IV) who underwent AVR and triple coronary artery bypass grafting. She also had moderate mitral regurgitation, but the mitral valve was not replaced. One patient, who had pulmonary edema preoperatively, required the use of inotropic agents and an intraaortic balloon to come off bypass. Three patients (14%)underwent resternotomy for bleeding secondary to coagulopathy, and acute renal failure developed in 1 patient (4.8%).Two patients (9.5%)required placement of a permanent pacemaker system because of complete heart block postoperatively. One patient underwent a tracheostomy for prolonged ventilation.
Late Clinical Follow-up There were three late deaths: at 2 months due to a gangrenous leg in an 80-year-old diabetic woman, at 15 months due to a blocked tracheostomy, and at 24 months due to hepatic metastases. All 17 of the survivors were traced (by April 1991). Mean follow-up was 20 5 3.1 months (range, 2 to 42 months). Fifteen of these patients were interviewed and examined, whereas 2 were interviewed over the telephone because of distance. There were no valve-related complications such as thromboembolic events, prosthetic endocarditis, hemolysis, or aortic insufficiency requiring reoperation. No patient required long-term anticoagulation, and none of them suffered any gastrointestinal hemorrhage. All the survivors were on less medication than preoperatively, and they all demonstrated excellent clinical improvement according to the NYHA functional classification (Fig 1).Two (11.8%)were in class IV, 11 (64.7%)in class III, and 4 (23.5%)in class I1 preoperatively, whereas 7 (41.2%) were in class I1 and 10 (58.8%) in class I postoperatively. Every patient had improved NYHA functional status.
Echocardiographic Follow-up Fifteen of the 17 patients had postoperative echocardiograms at the time of the study (average time, 20 2 3.1 months; range, 2 to 42 months). In 1 patient it was impossible to obtain an adequate Doppler signal to calcu-
1184
KALLIS ET AL 19-mmCARPENTIER-EDWARDS SUPRAANNULAR VALVE
NYHA Class
Preor>
Postoo
I I1 111 IV Fig 1 . Comparison of the Nao York Heart Association (NYHA) functional status of the 17 survivors preoperatively and postoperatively (time of follow-up).
late the transprosthetic gradient and valve area. The two-dimensional echocardiogram demonstrated hypertrophy of the left ventricle and good left ventricular function in the other 14 patients. There was no evidence of structural failure of any of the prostheses, but there was a minor paraprosthetic leak in 1 patient. This was not significant hemodynamically, however, as the patient was in NYHA functional class I. The mean cardiac output at rest was 3.92 ? 0.17 L/min (range, 3.2 to 5.1 L/min) with a cardiac index of 2.5 f 0.11 L min-’ * m-’ (range, 2.1 to 3.2 L * min-’ m-’), which is at the lower end of the normal range for 75-year-olds. The average maximum instantaneous gradient at rest was 34.1 k 2.7 mm Hg (range, 19 to 52 mm Hg). The mean effective valve area was 1.1 It 0.09 cm2 (range, 0.6 to 1.8 cm2).
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Comment Aortic valve replacement in the small aortic root presents a special challenge to the surgeon in regard to both operative technique and selection of prosthesis. These patients are predominantly older women with small body surface areas and severe calcific aortic stenosis, as confirmed by our patient population. When choosing a prosthesis for these patients three main factors have to be considered. First, such patients are unable to withstand difficult and prolonged procedures, which carry a high mortality and morbidity [l,101. Second, the hemodynamic performance of the prosthesis chosen must be adequate to avoid valve prosthesispatient mismatch, which would prevent clinical improvement of the patient [6]. Third, use of anticoagulants in elderly patients should be avoided if possible. Enlargmg the aortic annulus, either with an incision through the annulus into the anterior mitral leaflet [lo] or with a more extensive aortoventriculoplasty (Konno procedure) [ll],is poorly tolerated in elderly patients with calcified aortic roots [12]. The small Starr-Edwards valves (7-A and 8-A) have unacceptable transprosthetic gradients and are associated with an increased perioperative mortality [13]. Catheterization data of patients with 19-mm St. Jude valves
showed a peak-to-peak gradient of 16 mm Hg and functional orifice area of 1.22 cm2 [3]. Echocardiographic assessment of the same valve showed a maximum instantaneous gradient of 38 mm Hg [14]. Catheterization of patients with a 19-mm Bjork-Shiley valve revealed a functional orifice area of 1.06 cm2 and a peak systolic gradient of 16 mm Hg [l]. Major bleeding complications occurred in 13% of these patients, and minor bleeding complications developed in a further 13% [I]. The main advantage of tissue valves is the avoidance of anticoagulants, but structural failure still remains a problem. Bojar and colleagues [4]reported a good hemodynamic profile of the 19-mm Ionescu-Shiley pericardial valve echocardiographically. The maximum instantaneous gradient was 17 mm Hg and the effective orifice area 1.2 cm2. They also confirmed low operative mortality and demonstrated excellent clinical improvement, but the valve was withdrawn from the market in 1987 because of unacceptable structural failure rates. The 19-mm modified Hancock valve has a peak systolic gradient of 22 mm Hg and a functional orifice area of 1.1 cm2 [2]. The standard Carpentier-Edwards prosthesis has a smaller width of the prosthetic base and an asymmetric annulus, which provides a more effective orifice to external diameter ratio. In vivo hemodynamic data of the 19-mm valve, however, are scarce. Catheterization data in 3 patients revealed a peak systolic gradient of 33 mm Hg and a functional orifice area of 1.1 cm2 [15]. Carpentier and colleagues [161 described the design and preservation techniques of the CE-SAV in 1982. The prosthesis was developed to be implanted in the supraannular position, rather than within the annulus, to provide an orifice of the same diameter as the patient’s annulus. Such an approach attempted to reduce the transvalvular gradient across the standard 19-mm valve. The in vivo hemodynamic performance of the 19-mm CE-SAV is largely unknown because of fear of unacceptable transprosthetic gradients and failure of clinical improvement of the patient. This study, however, demonstrates that AVR with a 19-mm CE-SAV leads to major symptomatic improvement of the patients despite moderate transprosthetic gradients. As seen in the scattergram in Figure 2 there was no correlation between transprosthetic gradient and body surface area. The higher gradients are therefore more likely to be due to variation of cardiac output than to valve prosthesis-patient mismatch. Foster and colleagues [2] also found that there was no correlation of transvalvular gradient at rest with the clinical status of the patients at follow-up. Continuouswave Doppler ultrasound estimates the maximum instantaneous gradient rather than the peak-to-peak gradient as measured at cardiac catheterization. The more physiological Doppler-defined gradient, therefore, may be as much as 20 mm Hg higher than the peak-to-peak gradient [17, 181. Jamieson and colleagues [19] in 1988 reported their overall clinical results in 1,167 patients in whom they implanted CE-SAVs of all sizes. The freedom from structural deterioration at 4 years was 99% and from all
KALLIS ET AL 19-mm CARPENTIER-EDWARDS SUPRAANNULAR VALVE
Ann Thorac Surg 1992;- 11825
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Fig 2. Scattergram of maximum instantaneous gradient and body surface area (BSA), showing no correlation (r = 0.15).
valve-related complications, 86%. They therefore concluded that the CE-SAV offers excellent intermediate clinical results. In conclusion, this study defines the normal in vivo hemodynamic profile of the 19-mm CE-SAV. It also demonstrates that its use is associated with low operative mortality and low incidence of valve-related complications, and offers major clinical improvement despite moderate transprosthetic gradients. We believe that this approach provides an alternative management strategy in the small elderly patients who would otherwise require a low-profile mechanical valve or enlargement of the aortic annulus.
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3. Wortham DC, Tri TB, Bowen TE. Hemodynamic evaluation of the St. Jude Medical valve prosthesis in the small aortic annulus. J Thorac Cardiovasc Surg 1981;81:615-20. 4. Bojar RM, Diehl JT, Moten M, et al. Clinical and hemodynamic performance of the Ionescu-Shiley valve in the small aortic root. J Thorac Cardiovasc Surg 1989;89:1087-95. 5. Revuelta JM, Duran CMG, Garcia-Rinaldi R. Performance of the Ionescu-Shiley pericardial valve in the small aortic annulus. In: Proceedings of the cardiac prosthesis symposium 111, September 1985. Montreux, Switzerland: Shiley, Inc, 1987 17-22. 6. Rahimtoola SH. The problem of valve prosthesispatient mismatch. Circulation 1978;5820-4. 7. Simpson IA, Houston AB, Sheldon CD, Hutton I, Lawrie TDV. Clinical value of Doppler echocardiography in the assessment of adults with aortic stenosis. Br Heart J 1985;53: 636-9. 8. Skjaerpe T, Hegrenaes L, Hatle L. Noninvasive estimation of valve area in patients with aortic stenosis by Doppler ultrasound and two-dimensional echocardiography. Circulation - * . 1985;72810-8. 9. Huntsman LL. Stewart DK. Barnes SR, Franklin SB, Colocousis JS, Hessel EA. Noninvasive Doppler determination of cardiac output in man. Clinical validation. Circulation 1983; 67593402. 10. Manouguian S, Seybold-EptingW. Patch enlargement of the aortic valve ring by extending the aortic incision into the anterior mitral leaflet: new operative technique. J Thorac Cardiovasc Surg 1979;78402-12. 11. Misbach GA, Turley K, LJllyot DJ, Ebert PA. Left ventricular outflow enlargement by the Konno procedure. J Thorac Cardiovasc Surg 1982;84:696-703. 12. Rastan H, Abu-Aishah N, Rastan D, et al. Results of aortoventriculoplasty in 21 consecutive patients with left ventricular outflow tract obstruction. J Thorac Cardiovasc Surg 1978;75:659-69. 13. Blank RH, Pupello DF, Bessone LN, Hamson EE, Sbar S. Method of managing the small aortic annulus during valve replacement. Ann Thorac Surg 1976;22356-61. 14. Panidis IF, Ross JR, Mintz GS. Normal and abnormal prosthetic valve function as assessed by Doppler echocardiography. J Am Coll Cardiol 1986;8:317-26. 15. Bove EL, Marvasti MA, Potts JL, et al. Rest and exercise hemodynamics following aortic valve replacement: a comparison between 19 and 21 mm Ionescu-Shiley pericardial and Carpentier-Edwards porcine valves. J Thorac Cardiovasc Surg 1985;90750-5. 16. Carpentier A, Dubost C, Lane E, et al. Continuing improvement in valvular prostheses. J Thorac Cardiovasc Surg 1982; 8327-42. 17. Cooper DM, Stewart WJ, Schiavone WA, et al. Evaluation of normal prosthetic valve function by Doppler echocardiography. Am Heart J 1987;114:576-82. 18. Reisner SA, Meltzer RS. Normal values for prosthetic valve Doppler echocardiographic parameters: a review. J Am SOC Echocardiogr 1988;1:200-10. 19. Jamieson WRE, Munro AI, Miyagishima RT. The CarpentierEdwards supraannular porcine bioprosthesis. A new generation of tissue valve with excellent intermediate clinical performance. J Thorac Cardiovasc Surg 1988;96652-66.