Doppler echocardiographic comparison of small (19 mm) bileaflet and pericardial heart valve prostheses in aortic position

Current indications for stentless aortic bioprostheses

The best aortic prostheses have been debated for decades. The introduction of stentless aortic bioprostheses was aimed at improving hemodynamics and potentially the durability of aortic bioprostheses. Despite the good short- and long-term outcomes after implantation of stentless aortic bioprostheses, their use remains limited owing to the technically demanding implantation techniques. Nevertheless, stentless aortic bioprostheses might be of special benefit in certain indications, where they could be a valuable addition to the surgical armamentarium.

Bioprosthetic Heart Valves: Impact of Implantation on Biomaterials

Prosthetic heart valves are commonly used in the treatment of valvular heart disease. Mechanical valves are more durable than the bioprosthetic valves; however, the need for long-term anticoagulant therapy renders them unsuitable for some patient groups. In this paper we discuss the different types and models of bioprosthesis, and in particular, pericardial bioprosthesis. We also discuss the preimplantation preparation processes, as well as their postimplantation changes and modes of failure.

Early Doppler-echocardiography evaluation of 597 prosthetic aortic valves

OBJECTIVES

This study was designed to describe the Doppler-echocardiography normal values in the early postoperative phase for Carpentier-Edwards Perimount Aortic Heart Valve bioprosthesis (CEP), St. Jude Medical (SJM) or Medical Regent (SJMR) Mechanical Heart Valves, evaluated by a single experienced echo-laboratory.

METHODS

Five hundred and ninety-seven consecutive patients in our hospital, who had had a CEP, a SJM or SJMR-17 mm implanted due to aortic stenosis, underwent a control Doppler-echocardiography evaluation 4-7 days after surgery. Hemodynamic performance of SJM, SJMR and CEP were accurately described, evaluating flow-dependent (trans-prosthetic velocities and gradients) and flow-independent (effective orifice area, indexed effective orifice area and Doppler velocity index) Doppler-echocardiography parameters.

RESULTS

Of the 597 patients 50.6% were women (n = 302). Mean age was 66.3 +/- 11.7 years. Mean body surface area (BSA) was 1.76 +/- 0.22 m. Mean ejection fraction was 55.3 +/- 10.3%. Two hundred and sixty CEPs and 337 St. Jude mechanical valves (301 SJM and 36 SJMR size-17) were implanted. Comparing size-by-size SJM to CEP, the former were basically less flow obstructive.

CONCLUSION

Our data confirm the wide range of variability, pointing out the need to perform routinely an accurate baseline Doppler-echocardiography evaluation of the hemodynamic profile of prosthetic aortic valves, including flow-dependent and independent parameters, to allow an adequate interpretation at follow-up.

Mitroflow Synergy Prostheses for Aortic Valve Replacement: 19 Years Experience With 1,516 Patients

BACKGROUND

Pericardial prostheses have been used as valvular substitutes since 1975. They combine excellent hemodynamic characteristics with a low risk of valve failure during long-term observation. The aim of this article is to describe the clinical long-term performance of the Mitroflow Synergy pericardial valve (Sorin Group Inc, Mitroflow Division, Vancouver, Canada) in the aortic position for as long as 19 years.

METHODS

Data were obtained between February 1985 and April 2004 from patients with aortic heart valve replacements (n = 1,464) or from patients with replacements of existing prosthetic aortic valves (n = 52). The age group distributions are less than 70 years (n = 175); 70 to 74 years (n = 462); 75 to 79 years (n = 532); 80 to 84 years (n = 273); and greater than or equal to 85 years (n = 74). The cause of the aortic valve lesions was combined (insufficiency and stenosis) in the majority of patients (62.4%). Concomitant procedures were performed in 897 patients (59.2%) and coronary artery bypass grafting was the most common (53.5%). Mean follow-up was 5.5 +/- 0.09 years. Total follow-up was 8,408 patient-years.

RESULTS

The early mortality (30 days) was 6.6% (n = 99) and late deaths were 60.8% (n = 921). Actuarial event-free rates at 5, 10, and 15 years of follow-up are given as mean +/- standard error for endocarditis: 96.9 +/- 0.5, 92.8 +/- 1.2, and 92.0 +/- 1.4, respectively; embolism: 96.7 +/- 0.6, 88.8 +/- 1.7, and 82.9 +/- 3.5, respectively; bleeding: 98.5 +/- 0.4, 97.2 +/- 0.6, and 94.4 +/- 1.7, respectively; structural valve deterioration: 99.0 +/- 0.3, 82.8 +/- 2.2, and 62.8 +/- 5.8, respectively; and reoperation: 98.2 +/- 0.4, 79.2 +/- 2.4, and 63.4 +/- 5.3, respectively. The rate of endocarditis, structural valve degeneration, and reoperation was lower in patients 75 years of age and older compared with younger patients, whereas embolism occurred more frequently in elderly than in younger patients.

CONCLUSIONS

Adverse events after implantation of Mitroflow aortic bioprosthesis rarely occurred during the first 5 years after valve replacement. The results of the prosthesis indicates reliable long-term morbidity rates and good durability in patients 75 years of age and older.

Aortic valve replacement: is valve size important?

OBJECTIVE

We sought to determine whether aortic prosthesis size adversely influences survival after aortic valve replacement.

METHODS

A total of 892 adults receiving a mechanical (n = 346), pericardial (n = 463), or allograft (n = 83) valve for aortic stenosis were observed for up to 20 years (mean, 5.0 +/- 3.9 years) after primary isolated aortic valve replacement. We used multivariable propensity scores to adjust for valve selection factors, multivariable hazard function analyses to identify risk factors for all-cause mortality, and bootstrap resampling to quantify the reliability of the results.

RESULTS

Twenty-five percent of patients had indexed internal orifice areas of less than 1.5 cm(2)/m(2) and more than 2 SDs (Z-value) below predicted normal aortic valve size. Mechanical valve orifices were smaller (1.3 +/- 0. 29 cm(2)/m(2), Z = -2.2 +/- 1.16) than pericardial (1.9 +/- 0.36 cm(2)/m(2), Z = -0.40 +/- 1.01) or allograft valves (2.1 +/- 0.50, Z = 0.24 +/- 1.17). The overall survival was 98%, 96%, 86%, 69%, and 49% at 30 days and 1, 5, 10, and 15 years postoperatively. Univariably, survival was weakly and inversely related to manufacturer valve size (P =.16) and internal orifice diameter (P =. 2) but completely unrelated to indexed valve area (P =.6) or Z-value (P =.8). These, and univariable differences among valve types (P =. 004), were accounted for by different prevalences in patient risk factors and not by valve size or type per se. Bootstrap resampling indicated that these findings had a less than 15% chance of being incorrect.

CONCLUSIONS

Survival after aortic valve replacement is strongly related to patient risk factors but appears not to be adversely affected by moderate patient-prosthesis mismatch (down to about 4 SDs below normal). Aortic root enlargement to accommodate a large prosthesis may be required in few situations.

Haemodynamic performance of aortic pericardial bioprostheses and bileaflet prostheses at rest and during exercise: implications for the surgical management of patients with small aortic roots

OBJECTIVE

To determine the haemodynamic behaviour, at rest and during exercise, of aortic valve pericardial bioprostheses and different sizes of bileaflet prosthesis.

DESIGN

Observational study.

SETTING

Tertiary medical centre.

PATIENTS AND INTERVENTIONS

74 patients (33 women, 41 men; mean age 64 years) in whom 40 pericardial bioprostheses and 34 bileaflet prostheses sized 19, 21, or 23 mm had been implanted to replace aortic valves.

MAIN OUTCOME MEASURES

Doppler echocardiography at rest and at peak exercise, between 12 and 47 months after surgery.

RESULTS

All patients achieved a significant increase in heart rate, systolic blood pressure, and cardiac output with exercise. Transvalvar pressure fall, valve area, and left ventricular systolic and diastolic function indices also underwent significant changes with exercise. Reductions in peak and mean transvalvar pressure, at rest and at peak exercise, were greater in patients with small valves (p < 0.05). Valve areas and effective area index were greater in the patients with larger valves (p < 0.001). There were no significant differences between patients with mechanical and biological prostheses with regard to transvalvar pressure fall and valve areas at rest and at peak exercise.

CONCLUSIONS

19 mm and 21 mm aortic prostheses and bioprostheses continue to create significant obstruction, particularly with exercise.

Cardiopulmonary response to maximal exercise in young athletes following the Ross procedure

BACKGROUND

Aortic prosthetic devices offer limitations that make them less than optimal valve substitutes because the vast majority are innately obstructive, especially at increased levels of hemodynamic function. The present study is designed to demonstrate the hemodynamics of the pulmonary autograft in 11 conditioned athletes who have undergone the Ross (pulmonary autograft) procedure. Data was compared to a group of 13 age-matched "normal athletes."

METHODS

All the Ross athletes had undergone the autograft procedure using the root replacement technique and were at least 3 months into their postrecovery phase. All athletes (both normal and Ross) underwent resting transthoracic echo followed by maximal exercise stress test (modified Bruce protocol) to exhaustion. Post-operative transesphogeal echocardiogram obtained within 90 seconds documented aortic valve gradient and velocity across the aortic valve.

RESULTS

In the Ross athlete group, maximum heart rate was 188 beats per minute, peak aortic valve gradient at rest (mm Hg) 7.69 (mean), velocity across the aortic valve at rest (cm per second) 129.40 (mean), peak aortic valve gradient at maximal exercise (mm Hg) 16.30 (mean), velocity across the aortic valve at maximal exercise (cm per second) 190.00 (mean). In the normal athlete group, maximum heart rate was 176 beats/minute, peak aortic valve gradient at rest (mm Hg) 5.97 (mean), velocity across the aortic valve at rest (cm per second) 120.54 (mean), peak aortic valve gradient at maximal exercise (mm Hg) 14.61 (mean), velocity across the aortic valve at maximal exercise (cm per second) 190.23 (mean).

CONCLUSION

The pulmonary autograft exhibits hemodynamic characteristics similar to the normal human aortic valve under conditions of enhanced cardiac output.

Aortic valve replacement for octogenarians: are small valves bad?

BACKGROUND

As the population ages, more octogenarians become candidates for aortic valve replacement. Many octogenarians, particularly women, have a small aortic annulus and there is uncertainty as to the optimal management of this situation in that age group.

METHOD

To examine this issue, we reviewed 248 octogenarians (mean age, 82.6 +/- 2.3 years; 58% men) who underwent primary isolated aortic valve replacement (n = 99), or aortic valve replacement and coronary revascularization (n = 149), between 1980 and 1995. Nineteen-millimeter valves were used in 26% of the patients.

RESULTS

In-hospital mortality was 8.9%, 5% for aortic valve replacement alone and 11.4% for aortic valve replacement and coronary revascularization. It was 12.5% for the 19-mm size valves compared with 7.7% for the bigger size valves (p = 0.24). Follow-up (mean interval, 4.4 years) demonstrated survival for all patients of 85%, 60%, and 30% and survival free from cardiovascular events of 80%, 45%, and 21% at 1, 5, and 10 postoperative years, respectively. Multivariate analysis identified triple-vessel disease and preoperative congestive heart failure as associated with increased risk for both in-hospital and late mortality (p < 0.05). Valve size did not influence late survival or event-free survival regardless of body surface area.

CONCLUSIONS

The use of small aortic valve prostheses in octogenarians does not adversely affect the incidence of early or late mortality or cardiac events.

Pericarbon pericardial valve prosthesis: midterm results of the aortic valve replacement

This clinical study was undertaken to verify the encouraging results of experimental studies regarding a new pericardial bioprosthesis. From May 1989 to November 1993, 204 patients underwent an aortic valve replacement with the Pericarbon (Sorin Biomedica Cardio S.p.A., Saluggia, Italy) prosthesis. A follow-up was 100% complete and extended to 65 months (total 408 patient-years, average 2.0+/-1.4 years). Mean age at the operation was 75.1+/-5.5 years and 96% were in NYHA clinical stage III or IV. There were 86 men and 118 women; 73 patients had an isolated aortic valve disease, 131 had a concomitant cardiosurgical procedure (coronary artery bypass grafting in 106 patients). The operative mortality (30-day mortality) rate was 11.8% (24/204). There were 24 late deaths (5.9+/-1.2% patient-year). The actuarial probability of survival was 68+/-5% at 5 years. Four patients died of valve-related causes (one thromboembolic complication, two endocarditis, one anticoagulant-related hemorrhage). Actuarial rate of freedom from valve-related death was 95+/-3% at 5 years. Valve-related morbidity included seven thromboembolic episodes (1.7% patient-year), four anticoagulant-related complications (0.9% patient-year), three endocarditis (0.7% patient-year) and one reoperation (0.2% patient-year). After 5 years freedom from thromboembolic events was 83+/-7%, from anticoagulant-related hemorrhage 96+/-2%, from endocarditis 97+/-2%, and from reoperation 99+/-1%. Echocardiographic study performed in 30 patients showed a paraprosthetic leak in four patients, a central leak in two, and cusp thickening in another three. The clinical data showed that the Pericarbon prosthesis has valve-related morbidity. The echocardiographic results suggest that the prosthesis can undergo a pathologic process during the first 5 years after implantation. This makes it necessary to continue the follow-up and include the larger number of patients in the echocardiographic investigation.

Influence of the size of aortic valve prostheses on hemodynamics and change in left ventricular mass: implications for the surgical management of aortic stenosis

Discussion of aortic valve replacement has primarily concerned the choice between tissue and mechanical prostheses. Less emphasis has been placed on prosthesis size. Despite technical advances increasing prosthesis orifice area, small valves implanted in the unenlarged aortic root may not be significantly less obstructive than the stenotic native valves they replace.

METHODS

In this work we studied 52 patients (31 women, 21 men; mean age 59.2 years) in whom valve prostheses sized 19, 21, 23, or 25 mm (30 bioprostheses and 22 tilting disc valves) had been implanted to replace stenotic aortic valves. Most patients with 19 or 21 mm prostheses were women. Doppler and conventional echocardiographic studies were performed in the 10 days preceding the operation and between 10 and 40 months (mean 18 months) after the operation. The patients receiving larger valve sizes had significantly larger body surface areas than those receiving smaller valve sizes (mainly women).

RESULTS

No significant differences were observed between preoperative and postoperative diameters or left ventricular systolic function parameters, but left ventricular mass and mass index decreased in all four groups (albeit nonsignificantly in the 19 mm group, and with less statistical significance in the 21 mm group than in the 23 and 25 mm groups). Postoperative peak and mean transvalvular pressure drops were significantly greater in the 19 mm group than in the other groups, and the 21 mm group had significantly greater transvalvular pressure drops than the 25 mm group. Postoperative effective valve area was significantly smaller in the 19 mm group than in the 21 mm group, and significantly smaller in the 21 mm group than in the 23 and 25 mm groups.

CONCLUSION

We conclude that despite undeniable recent improvements in the design of artificial heart valves, 19 mm aortic prostheses continue to create significant obstruction of the left ventricular outflow tract and, possibly as a consequence of this, fail to bring about significant reduction in left ventricular hypertrophy.