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Ann Thorac Surg 1997;64:1753-1756
© 1997 The Society of Thoracic Surgeons

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Original Articles: Cardiovascular

Comparative Rest and Exercise Hemodynamics of Allograft and Prosthetic Valves in the Aortic Position

Department of Surgery III, Nara Medical University, Nara, Japan

Accepted for publication June 20, 1997.

	Abstract

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 
Background. Allograft aortic valve replacement has gained widespread acceptance. However, there is little information about in vivo allograft valve function at rest and during exercise.

Methods. Cardiac catheterization was performed to measure hemodynamic variables at rest and during supine bicycle exercise in 44 patients who had had aortic valve replacement using allograft valves or Bicer or St. Jude Medical prosthetic valves 19 to 27 mm in diameter. Sixteen patients received an allograft valve; 17, a Bicer valve; and 11, a St. Jude Medical valve. There were no significant differences between the three groups in age, body surface area, left ventricular end-systolic and end-diastolic volume indices, exercise cardiac index, exercise heart rate, or work load achieved. Left ventricular and ascending aortic pressures were measured simultaneously according to the transseptal method.

Results. The mean pressure gradient was generally higher for the Bicer and St. Jude Medical valves than for the allograft valves, both at rest and during exercise. Significant differences were obtained in patients with small-sized valves (21 and 23 mm); pressure gradients were higher in the prosthetic valve groups. In patients with large-sized prosthetic valves (25 mm), there were no significant differences between the three groups at rest and during exercise. However, there was no pressure gradient at all for allograft valves.

Conclusions. Exercise cardiac catheterization confirms that the allograft aortic valve is an ideal substitute from the hemodynamic aspect, particularly in patients with a small aortic root and in those who perform strenuous exercise.

	Introduction

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 
Allograft aortic valves have been used in the replacement of diseased human aortic valves. O'Brien and colleagues [1] developed the techniques currently used for homograft valve cryopreservation and reported excellent intermediate-term function of cryopreserved valves. Selection of a prosthesis with a favorable hemodynamic profile is an important consideration for cardiovascular surgeons. Allograft valve function has been little analyzed in detail at rest and during exercise. The purpose of the present study was to compare the hemodynamic performance of allograft, St. Jude Medical (SJM, St. Paul, MN), and Bicer prosthetic valves in the aortic position both at rest and during exercise by the transseptal catheterization technique.

	Material and Methods

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 
Preoperative Patient Status
Forty-four patients who had undergone aortic valve replacement were hemodynamically assessed and compared at rest and during exercise. Sixteen patients had a cryopreserved allograft valve, 17 had a Bicer valve, and 11 had a SJM valve. The preoperative aortic lesion was isolated aortic regurgitation in 21 patients (48%), isolated aortic stenosis in 8 (18%), and combined stenosis and regurgitation in 15 (34%). Patients were excluded if additional procedures such as coronary artery bypass grafting or other valvular operations were performed. Forty-two patients were in normal sinus rhythm and 2, in atrial fibrillation before and after the operation.

Characteristics of the patients are shown in Table 1. The following valve sizes were used: allograft valves—19 mm (1 patient), 21 mm (2 patients), 23 mm (10), 25 mm (2), and 27 mm (1) (mean valve size, 23.0 ± 1.8 mm); Bicer valves—21 mm (5), 23 mm (7), and 25 mm (5) (mean valve size, 23.0 ± 1.6 mm); and SJM valves—21 mm (3), 23 mm (6), and 25 mm (2) (mean valve size, 23.0 ± 1.4 mm). There were no significant differences among the three groups in body surface area, age, mean follow-up, or left ventricular systolic function.

Cardiac Catheterization Studies
In all 44 patients, cardiac catheterization and exercise studies were performed 12 months after valve replacement to measure hemodynamic variables and pressure gradients across the implanted valves. Left ventricular and ascending aortic pressures were obtained simultaneously according to the transseptal approach (the Brockenbrough method) [3]. Aortic and left ventricular pressures were measured using two 5F pigtail-shaped catheters. One catheter was positioned 3 to 4 cm above the allograft or prosthetic valve, and the other was placed in the left ventricle where there was no premature ventricular contraction. The catheter positions were confirmed by roentgenography at rest and during exercise. Systolic pressure gradients were measured using a pressure transducer (model P23XL; Spectramed Medical Products, Singapore), and the mean was obtained by averaging the instantaneous gradients measured over three cardiac cycles in sinus rhythm and five cardiac cycles in atrial fibrillation. The transducers were properly balanced by calibration with a Veri-Cal system (Utah Medical Products Inc). Cardiac output was measured by the thermodilution method. Aortic valve flow was calculated as cardiac output divided by systolic ejection time.

Using a supine bicycle ergometer, a starting work load of 25 W was applied and increased by 25 W at 2-minute intervals. Tests were limited by symptoms. This study was approved by the hospital ethics committee, and informed consent was obtained from each patient.

Statistical Analysis
Data are expressed as the mean ± the standard deviation. Analysis of variance was used to determine if mean values differed significantly between the groups. A paired Student t test was used for comparisons of rest and exercise variables. Significance was established at a p value of less than 0.05.

	Results

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 
Transvalvular Aortic Regurgitation
Trivial aortic regurgitation was detected in 5 of the 16 patients with allograft valves; no regurgitation was present in the remaining 11 patients. Also, trivial transvalvular regurgitation, which is normally present, was noticed in the Bicer and SJM prostheses.

Hemodynamic Variables
Tables 2 and 3 show the hemodynamic data for the three groups at rest and during exercise. There were no significant intergroup differences in heart rate, left ventricular end-diastolic pressure, or cardiac index at rest or during exercise. Left ventricular end-diastolic volume, left ventricular end-systolic volume, and ejection fraction were similar at rest in the three groups.

	Comment

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 
Allograft Valve Function
Aortic valve replacement using a cryopreserved allograft valve results in excellent hemodynamic performance with essentially no thromboembolic complications and reasonable durability. Accordingly, allograft aortic valve replacement has recently gained widespread acceptance. Some investigators [4] found that no pressure gradient through the allograft valve exists at rest after the operation, but there is little information about in vivo allograft valve function during exercise. Using Doppler echocardiography, Jaffe and colleagues [5] demonstrated that the mean pressure gradient for allograft valves was 5.9 to 6.7 mm Hg at rest and 8.1 to 9.7 mm Hg during exercise. In our study, the mean pressure gradient for allograft valves was 0 ± 0 mm Hg at rest and 0.5 ± 2.0 mm Hg during exercise by the pressure manometer method. Only 1 patient with a small allograft valve showed a mean pressure gradient of 8 mm Hg (aortic valve flow, 182 mL/min) during exercise, although it was 0 mm Hg at rest.

Detailed comparisons are difficult because Jaffe and coauthors [5] measured the mean pressure gradients by Doppler echocardiography, which may lead to somewhat different results from those obtained by cardiac catheterization. The difference in peak left ventricular pressure to peak aortic pressure (peak-to-peak gradient) is sometimes used to compare the hemodynamic performance of different prosthetic valves because it is easy to derive from a cursory glance at the pressure tracings. However, this measurement has little physiologic meaning because the two peaks do not occur at the same time in the cardiac cycle. Thus, no real peak-to-peak gradient exists [6]. For this reason, the mean pressure gradient was measured and used for comparison in this study.

Jaffe and colleagues [5] also demonstrated that the aortic valve area showed no significant difference between patients with allograft valves and those with SJM valves (1.8 ± 0.6 cm² versus 1.4 ± 0.5 cm²). In our study, the aortic valve area could not be hemodynamically calculated because the mean gradient across the allograft valves was 0 mm Hg in all patients but 1. Barratt-Boyes and associates [7] demonstrated that repeat catheterization studies at a mean interval of 5 years showed no increase in the mean pressure gradient of the allograft at rest. Although we did catheterization studies only once postoperatively, repeat Doppler echocardiography has shown no increase in resting gradient during follow-up of 2.8 ± 1.2 years.

St. Jude Medical Valve Function
Many investigators [8–10] have shown excellent clinical results and good prosthetic valve function for SJM valves. Wortham and colleagues [11] demonstrated that the average mean systolic pressure gradient across 19-mm and 21-mm SJM valves in the aortic position was 20 mm Hg (range, 10 to 28 mm Hg) at rest and 38 mm Hg (range, 30 to 48 mm Hg) with exercise. In their study, 6 patients with a 19-mm SJM valve showed an average mean pressure gradient of 22 mm Hg at rest and 38 mm Hg during exercise. Although our study included only 1 patient with a 19-mm allograft valve, the mean pressure gradient was 0 mm Hg at rest and 8 mm Hg during exercise. Our data suggest that the hemodynamic function of allograft valves is superior to that of prosthetic valves, particularly in the small aortic annulus.

Bicer Valve Function
Our previous study [12] reported good survival and excellent freedom from thromboembolism for Bicer valves in the aortic position. However, the Bicer valve, particularly during exercise, had a higher pressure gradient than the SJM prosthesis in all valve sizes compared in the present study.

Conclusion
We conclude that the allograft aortic valve is an ideal substitute from the hemodynamic aspect, particularly in patients with a small aortic root and in patients who perform strenuous exercise.

	Footnotes

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 
Address reprint requests to Dr Kitamura, Department of Surgery III, Nara Medical University, 840 Shijo-cho, Kashihara, Nara, 634 Japan.

	References

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 

1. O'Brien M, McGiffin D, Stafford E, et al. Allograft aortic valve replacement: long-term comparative clinical analysis of the viable cryopreserved and antibiotic 4°C stored valve. J Cardiac Surg 1991;6(Suppl):534–43.[Medline]
2. Niwaya K, Sakaguchi H, Kawachi K, Kitamura S. Effect of warm ischemia and cryopreservation on cell viability of human allograft valves. Ann Thorac Surg 1995;60:S114–7.[Medline]
3. Ross J Jr. Considerations regarding the technique for transseptal left heart catheterization. Circulation 1966;34:391–9.[Abstract/Free Full Text]
4. Yankah A, Sievers H, Bursch J, et al. Orthotopic transplantation of aortic valve allografts. Early hemodynamic results. Thorac Cardiovasc Surg 1984;32:92–5.[Medline]
5. Jaffe W, Coverdale H, Roche A, Whitlock R, Neutz J, Barratt-Boyes B. Rest and exercise hemodynamics of 20 to 23 mm allograft, Medtronic Intact (porcine), and St. Jude Medical valves in the aortic position. J Thorac Cardiovasc Surg 1990;100:167–74.[Abstract]
6. Carabello B. Advances in the hemodynamic assessment of stenotic cardiac valves. J Am Coll Cardiol 1987;10:912–9.[Abstract]
7. Barratt-Boyes BG, Roche AHG, Brandt PWT, Smith JC, Lowe JB. Aortic homograft valve replacement. A long-term follow-up of initial series of 101 patients. Circulation 1969;40:763–9.[Abstract/Free Full Text]
8. Arom KV, Nicoloff DM, Kersten TE, Northrup WF III, Lindsay WG, Emery RW. Ten years' experience with the St. Jude Medical valve prosthesis. Ann Thorac Surg 1989;47:831–7.[Abstract]
9. Fernandez J, Laub G, Adkins M, et al. Early and late phase events after valve replacement with the St. Jude Medical prosthesis in 1200 patients. J Thorac Cardiovasc Surg 1994;107:394–407.[Abstract/Free Full Text]
10. Irahim M, O'Kane H, Cleland J, Gladstone D, Sursam M, Patterson C. The St. Jude Medical prosthesis. A thirteen-year experience. J Thorac Cardiovasc Surg 1994;108:221–30.[Abstract/Free Full Text]
11. Wortham D, Tri T, Bowen T. Hemodynamic evaluation of the St. Jude Medical prosthesis in the small aortic annulus. J Thorac Cardiovasc Surg 1981;81:615–20.[Abstract]
12. Kawachi K, Kitamura S, Morita R, et al. Clinical results and in vivo valve function after implantation of a Bicer valve prosthesis in the aortic position. J Am Coll Cardiol 1989;14:332–7.[Abstract]

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This Article Abstract Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Junichi Hasegawa Soichiro Kitamura Shigeki Taniguchi Kazuo Niwaya Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Hasegawa, J. Articles by Kameda, Y. Search for Related Content PubMed PubMed Citation Articles by Hasegawa, J. Articles by Kameda, Y.