Background and aim of the study: Due to an asymmetrical/eccentric flow profile at the level of the aortic valve, there is an optimal orientation for each aortic valve design. This study evaluates intraoperative flow dynamics (turbulence and pressure gradient) and follow up results (pressure gradient and left ventricular mass regression) for Medtronic Hall tilting disc (MH) and St. Jude Medical bileaflet (SJM) valves, with both valves in their optimum orientation as defined in previous animal experiments.

Methods: In a randomized prospective study, MH and SJM valves (size > or = 23 mm) were implanted in their optimum orientation in 24 patients with aortic stenosis. Turbulence measurements were performed intraoperatively via a perivascular ultrasound transducer; Reynold's normal stress (RNS) values were calculated as key markers for turbulent stresses. Transvalvular pressure gradients, interventricular septum and posterior wall thickness were measured by transesophageal echocardiography intraoperatively and six months postoperatively.

Results: Mean valve size was 23.8 mm in both groups. Intraoperative RNS values (MH 7.5 +/- 2.2 N/m2 versus SJM 9.8 +/- 2.3 N/m2) and pressure gradients (MH 10.0 +/- 2.6 mmHg versus SJM 20.0 +/- 3.4 mmHg) were significantly lower for the tilting disc valve. At six months follow up, pressure gradients were reduced by half for both valves (MH 5.3 +/- 1.7 mmHg; SJM 10.4 +/- 2.3 mmHg), with the difference between the valves being maintained. Left ventricular mass regression was accelerated for MH patients with regard to interventricular septum thickness.

Conclusion: Our results indicate that the tilting disc mechanism shows superior hemodynamic performance with respect to turbulence and transvalvular pressure gradients compared with the bileaflet mechanism when both valves are implanted in their optimum orientation. This led to significant acceleration of interventricular septum mass regression. The superiority of the tilting disc mechanism is more pronounced in the smaller-sized valves.

How to cite: Kleine, P., Hasenkam, M. J., Nygaard, H., Perthel, M., Wesemeyer, D., & Laas, J. (2000). Tilting disc versus bileaflet aortic valve substitutes: intraoperative and postoperative hemodynamic performance in humans. The Journal of heart valve disease, 9(2), 308–312.

Background and aim of the study: Our aim was to compare the CarboMedics (CM) and Monostrut (M) mechanical heart valve prostheses in the aortic position. These prostheses have been studied extensively in the past, both have well-defined characteristics, and have not been modified for many years.

Methods: This randomized, prospective study included 200 consecutive patients; 100 received the CM prosthesis and 100 the M prosthesis. Both groups were statistically similar in terms of age, aortic valve lesion, and preoperative clinical and surgical characteristics. Mean follow up was 5.58 years (range: 2 months to 11 years); total follow up was 1095 patient-years (pt-yr) (CM 5.33 years, 528 pt-yr; M 5.85 years, 567 pt-yr).

Results: Early mortality rates were 1% in the CM group and 3% in the M group. Late mortality rates were 7% and 9%, respectively. Mean (+/- SD) survival rates at 11 years were 80.51 +/- 7.36% for the CM group and 79.62 +/- 5.59% for the M group. There were no cases of mechanical valve failure in either group. The linearized rates of major thromboembolism were 1.03% and 0.20% per pt-yr for the CM and M groups, respectively; the rates of major bleeding-events were 0.71% and 0.61% per pt-yr, respectively. The rate of paravalvular leak was 0.35% and 0% per pt-yr in the CM and M groups, respectively. Postoperative NYHA class was I-II in 95.83% of CM patients, and in 94.37% of M patients.

Conclusion: Clinical results with CarboMedics and Monostrut prostheses are highly satisfactory, but no superiority of one valve over the other can be identified.

How to cite: de la Fuente, A., Sanchez, R., Romero, J., Berjon, J., Imizcoz, M. A., Fernandez, J. L., & Moriones, I. (2000). CarboMedics and Monostrut valves: clinical and hemodynamic outcomes in a randomized study. The Journal of heart valve disease, 9(2), 303–307.

Background and aim of the study: The use of echocardiography to determine prosthetic valve hemodynamics has become generally accepted; however, there are still many differing methodologies in use. The continuity equation, which uses the ratio of the subaortic and transaortic velocity-time integrals for determining aortic effective orifice area (EOA), has been established as an accurate method. Another method using the more easily measured peak velocities in ratio has also been employed. These methods were compared to determine if the simpler method gave equivalent results.

Methods: Early postoperative echocardiographic data on prosthetic valves from the MCRI Multicenter Trial were used to compare the two methods of calculating EOA (A2). Results using the two methods were compared by paired t-tests, the Wilcoxon signed rank test, regression and Bland-Altman analysis.

Results: Despite a good correlation between the two methods (r = 0.91), results were different when compared by a paired t-test. On average, results by the modified method were 0.2 cm2 lower, but in 28% of cases they were in fact higher than the classical method.

Conclusion: The modified continuity equation based on the peak velocity ratio does not give the same result as the classical formula based on the velocity-time ratio. The modified method cannot reliably be substituted for the classical method in normally functioning On-X valves.

How to cite: Chambers, J., & Ely, J. (2000). A comparison of the classical and modified forms of the continuity equation in the On-X prosthetic heart valve in the aortic position. The Journal of heart valve disease, 9(2), 299–302.

Background and aim of the study: Characterization of the severity of a stenotic aortic valve relies on accurate measurement of the pressure drop across the valve. A simplified form of the Bernoulli equation has been used to estimate pressure drops using Doppler ultrasound, but these measurements often overestimate gold standard measurements performed during cardiac catheterization. Sources of discrepancy between the Doppler and catheter measurements have been identified, but no method has been developed to fully reconcile the two techniques.

Methods: In this study we developed a correction to the clinical form of the Bernoulli equation based on receiving chamber geometry and turbulent jet profiles. The theoretical treatment of the mechanical energy balance, assuming a shape to the stenotic jet profile is described, and the assumptions in our model are discussed. The use of the model was then demonstrated in an in vivo clinical study in which simultaneous Doppler and catheter data were obtained.

Results: Discrepancies between Doppler and catheter are shown to be a function of the predicted pressure recovery location based on our assumed profile. There exists a distance of about 8.67 valve radii downstream where agreement in peak pressure gradients is theoretically achieved.

Conclusion: The results demonstrate the ability to characterize pressure recovery distal to the valve. Our approach, to substitute a more appropriate velocity profile into the mechanical energy balance, unifies geometric parameters and the physics of turbulent jet flow in an equation involving quantities already routinely measured in an echocardiographic examination of aortic stenosis. This allows for both the maximal and recovered pressure gradient to be obtained from the Doppler data. These results have implications for optimal pressure sensor placement for the assessment of aortic stenosis and also for the evaluation of prosthetic heart valves in vitro.

How to cite: VanAuker, M. D., Hla, A., Meisner, J. S., & Strom, J. A. (2000). Simultaneous Doppler/catheter measurements of pressure gradients in aortic valve disease: a correction to the Bernoulli equation based on velocity decay in the stenotic jet. The Journal of heart valve disease, 9(2), 291–298.

Tricuspid valve myxomas are extremely rare, with only 21 case reports having been identified in the literature. A case of tricuspid valve myxoma in a 5-year-old child is presented. The tumor was a solid type myxoma attached to the septal leaflet of the tricuspid valve, and manifested as right-sided heart failure. The patient successfully underwent surgical excision of the tumor without any recurrence during a follow up of 30 months.

How to cite: Bolourian, A. A., Karimi, M., & Mirzaie, A. (2000). Myxoma of the tricuspid valve. The Journal of heart valve disease, 9(2), 288–290.

The management of patients with severe tricuspid regurgitation (TR) requires the clinician to clarify the mechanism of regurgitation. Primary disorders of the tricuspid valve, either congenital or acquired, may be readily identified by echocardiography. Severe TR most often results from left-sided heart disease and secondary pulmonary hypertension. Cardiomyopathic processes may also cause right ventricular failure and functional TR. We report three patients with severe TR due to idiopathic annular dilation. The tricuspid valves were otherwise normal on surgical inspection, and the pulmonary pressures were not significantly elevated. Each patient was aged over 65 years and had chronic atrial fibrillation with preserved left ventricular systolic function. Surgical treatment was associated with marked clinical improvement. Clinicians should recognize this unusual but treatable cause of right-sided congestive heart failure.

How to cite: Girard, S. E., Nishimura, R. A., Warnes, C. A., Dearani, J. A., & Puga, F. J. (2000). Idiopathic annular dilation: a rare cause of isolated severe tricuspid regurgitation. The Journal of heart valve disease, 9(2), 283–287.

Background and aims of the study: The prosthetic ring annuloplasty and incompletely encircling suture techniques are effective methods of tricuspid valve repair when the problem is only annular dilatation, but not when organic tricuspid valve disease is present. A surgical technique of valve repair has been developed that is equally effective in correcting purely functional as well as organic valvular incompetence.

Methods: The Manipal method of repairing the incompetent tricuspid valve consists of three steps: (i) anteroseptal commissurotomy and asymmetric 'U-on-side' suture annuloplasty, to push the plane of coaptation of the anterior and septal leaflets into the right ventricle; (ii) a semicircular De Vega-type of plicating suture through the annulus, starting and ending just cephalad to the posteroseptal commissure and extending anticlockwise to a point just caudal to the meridian, to exclude the posterior leaflet; and (iii) tying the plicating suture after positioning a 3M Starr-Edward valve sizer across the tricuspid valve (in an adult), to ensure that the valve orifice is not excessively narrowed.

Results: Between July 1986 and January 1997, the Manipal method was used to repair 52 tricuspid valves, always combined with surgery for the mitral and/or aortic valve. Tricuspid stenosis of varying degree was present in 61% of cases. One of two hospital deaths was related to the repaired valve. Although the proportion of patients followed up fell progressively to 33% at 10 years, none of the patients either seen personally or who had replied to a postal questionnaire (78% of total patients) required reoperation for valve regurgitation or obstruction. No patient had more than mild tricuspid regurgitation clinically, even seven and 10 years after tricuspid valve repair surgery.

Conclusion: This alternative method of tricuspid valve repair is simple to execute, is equally effective in correcting both pure tricuspid regurgitation and organic tricuspid valve disease, and appears to be extremely stable.

How to cite: Shatapathy, P., Aggarwal, B. K., & Kamath, S. G. (2000). Tricuspid valve repair: a rational alternative. The Journal of heart valve disease, 9(2), 276–282.

A 68-year-old woman was admitted to hospital for possible mitral valve surgery for severe mitral regurgitation (MR). Six months before admission, a DDD pacemaker was implanted for symptomatic bradycardia. She developed atrial fibrillation and the pacer was changed to a VVI mode. At cardiac catheterization, the pulmonary artery and wedge pressures were elevated; coronary angiography showed non-obstructive coronary artery disease. 2-D echocardiography confirmed preserved left ventricular function, severe MR and moderate tricuspid regurgitation. The change in pacing had a dramatic effect on MR severity; ventricular pacing was associated with a MR jet that occupied a larger area of the left atrium than with the unpaced rhythm, the continuous-wave mitral regurgitant Doppler profile was 'dagger'-shaped, and the signal intensity stronger compared with the unpaced rhythm. These findings are consistent with severe MR. The pacer was reprogrammed to reduce the pacing rate from 70 to 45 beats/min, allowing an unpaced rhythm for the most part. The patient improved and was discharged two days later. Six months later she was asymptomatic; repeat echocardiography confirmed mild to moderate MR.

How to cite: Hanna, S. R., Chung, E. S., Aurigemma, G. P., & Meyer, T. E. (2000). Worsening of mitral regurgitation secondary to ventricular pacing. The Journal of heart valve disease, 9(2), 273–275.

Background and aim of the study: Cervical vagal stimulation in rabbits frequently causes systolic murmur with bigeminy due to premature ventricular contractions. The bigeminy disappears in a few minutes, but the systolic murmur persists for a few days. Peculiar lesions of the mitral valves, mitral annulus and papillary muscles, and an increase in left atrial weight, frequently develop in a week. In this study, color Doppler echocardiography was used to examine whether the systolic murmur was due to mitral regurgitation.

Methods: Echocardiographic monitoring was carried out in anesthetized rabbits restrained in the supine position.

Results: Doppler echocardiography and phonocardiography showed systolic murmur at 6 h, three days, and at one, two, three and four weeks after vagal stimulation. At 6 h after stimulation, phonocardiography showed systolic click and late systolic murmur; Doppler echocardiography showed marked mitral regurgitation. The systolic murmur and mitral regurgitation were attenuated and the papillary muscle was swollen three days after vagal stimulation. Following stimulation, mitral regurgitation disappeared within one week, and papillary muscle swelling improved after three weeks.

Conclusion: Doppler echocardiography confirmed that systolic murmur caused by vagal stimulation in rabbits was due to mitral regurgitation.

How to cite: Ashida, T., Okuno, S., Ebihara, A., Sugiyama, T., & Fujii, J. (2000). Transient mitral regurgitation following vagal stimulation-induced ventricular arrhythmia in rabbits: a color Doppler echocardiographic study. The Journal of heart valve disease, 9(2), 269–272.

Background and aim of the study: Percutaneous transvenous mitral commissurotomy (PTMC) has revolutionized the treatment of patients with symptomatic mitral stenosis and is now established as the procedure of choice. Despite high technical expertise in PTMC using the Inoue balloon, mitral regurgitation (MR) remains a major procedure-related complication. We retrospectively analyzed our data of PTMC using the Inoue balloon with regard to the incidence of MR, its likely causative mechanism, and follow up of these patients.

Methods: During the past ten years, PTMC was performed in 3,650 patients (median age 26 years; range: 8-76 years), of whom 910 (24.9%) were juveniles. Preprocedure mitral valve area (MVA) was 0.9 +/- 0.4 cm2 (range: 0.3-1.3 cm2); MR was mild in 1,396 cases (38.2%), moderate in 394 (10.8%) and severe in 22 (0.6%). None of the patients was rejected on the basis of echocardiographic score.

Results: The procedure was successful in 3,276 (89.8%), with post-procedure MVA of 1.7 +/- 0.6 cm2 (range: 1.4-2.6 cm2), and without development of any major complication. Severe MR was seen in 120 patients (3.3%), of whom 66 (1.8%) required urgent mitral valve replacement (MVR). Echocardiography in these latter patients showed leaflet rupture in 48 (72.7%), chordal rupture in 12 (18.2%) and excessive commissural tear in six (9.1%). Fifty-four patients (1.5%) with severe MR post PTMC were followed with medical treatment; echocardiography in these patients revealed chordal rupture in 40 (74.1%) and excessive commissural tear in 14 (25.9%). Follow up data were available in 49 patients (1.3%); 30 (0.8%) required MVR and 19 (0.5%) were in NYHA class II at a median follow up of 24 months. Moderate MR was seen in 188 cases (5.1%), with predominant causative mechanisms of excessive commissural tear in 120 (63.8%) and chordal rupture in 68 (36.2%). Severity of MR worsened in 30 cases (0.8%), of which 20 (0.6%) required elective MVR on follow up. MR decreased in 58 patients (1.6%), in whom excessive commissural tear was the causative mechanism.

Conclusion: Significant MR (moderate or severe) after PTMC was seen in 308 patients (8.4%), of whom 116 (3.2%) required MVR urgently or on follow up. All patients with leaflet rupture during PTMC developed severe MR and required urgent MVR. There was a tendency for the severity of MR to decrease with time in cases where excessive commissural tear was the causative mechanism.

How to cite: Kaul, U. A., Singh, S., Kalra, G. S., Nair, M., Mohan, J. C., Nigam, M., & Arora, R. (2000). Mitral regurgitation following percutaneous transvenous mitral commissurotomy: a single-center experience. The Journal of heart valve disease, 9(2), 262–268.

Background and aim of the study: Severe heart valve disorder has been reported in patients receiving a combination of the anorectic drugs fenfluramine and phentermine. The exact molecular mechanisms involved remain unknown. Fenfluramine alters the serotonin level in the brain, while phentermine interferes with the pulmonary clearance of serotonin; these data suggest that serotonin levels affect regulation of valve function. The aim of the present study was to characterize the serotonin receptor (5-hydroxytryptamine) subtypes expressed in the interstitial cells of human heart valves.

Methods: Interstitial cells were isolated and cultured from the aortic, pulmonary, mitral and tricuspid valves of recipient hearts obtained during transplantation. Total RNA was extracted from cultured cells in order to determine gene expression by reverse transcription-polymerase chain reaction (RT-PCR) using 5-hydroxytryptamine (5-HT) subtype-specific primer pairs.

Results: The results show that: (i) 5-HT 1B and 1D receptor subtypes are expressed in all four heart valves. This is significant as the 1B and 1D receptor subfamilies are the target of the anti-migraine drug sumatriptan, and these receptors regulate cardiac function and movement; (ii) 5-HT 1A, 5-HT 1E and 5-HT 1F are not expressed in interstitial cells isolated from the valves.

Conclusion: We conclude that preliminary evidence exists for the presence of distinct subsets of 5-HT receptors in human heart valves, indicating that interstitial cells of the valves potentially respond to serotonin levels.

How to cite: Roy, A., Brand, N. J., & Yacoub, M. H. (2000). Expression of 5-hydroxytryptamine receptor subtype messenger RNA in interstitial cells from human heart valves. The Journal of heart valve disease, 9(2), 256–261.

Background and aim of the study: The mechanisms that regulate the function of the aortic valve are not fully understood. Cusp tissue has been shown to have contractile properties, but little is known as to which receptors mediate these effects.

Methods: We have examined, using isolated organ baths, the response of porcine aortic valve leaflets to a range of vasoactive agents including endothelin-1, noradrenaline, adrenaline, the thromboxane (TX) A2 mimetic U46619, 5-hydroxytryptamine (5-HT), histamine and angiotensin II. The viability of each individual leaflet was tested by the addition of 90 mM KCl.

Results: All agents tested, with the exception of angiotensin II, were capable of inducing concentration-dependent contractions of the valve leaflets. The responses to endothelin-1 and U46619 were significantly greater than those of all the other agents tested. Responses to endothelin-1 could be inhibited by 10(-5) M of the mixed ET(A/B) receptor antagonist bosantan. The response to both catecholamines was blocked by 10(-6) M yohimbine, but not by 3 x 10(-7) M prazosin, indicating the presence of alpha2-adrenoceptors. The response to histamine was mediated exclusively by H1-receptors, as judged by the antagonistic effect of 10(-6) M of the H1-receptor antagonist mepyramine. The response to 5-HT could be blocked by 10(-6) M of the 5-HT2A-receptor antagonist ketanserin, and that of U46619 by 10(-6) M of the TXA2-receptor antagonist SQ30741.

Conclusion: These results demonstrate the range of receptor systems that can mediate contraction of aortic valve leaflets. Further studies are required to elucidate the role of these receptors in the physiology and pathophysiology of the aortic valve.

How to cite: Chester, A. H., Misfeld, M., & Yacoub, M. H. (2000). Receptor-mediated contraction of aortic valve leaflets. The Journal of heart valve disease, 9(2), 250–255.

Background and aim of the study: The treatment of bioprosthetic tissue routinely involves the use of glutaraldehyde, although the specific chemistry of glutaraldehyde fixation is not fully understood. Descriptions of definitive work on this reaction using model compounds are limited. The aim of the present study was to increase our understanding of the chemistry involved in the treatment of collagen-rich tissue with glutaraldehyde. Initially, 6-aminohexanoic acid (6-AHA) was used to model the lysine/hydroxylysine molecules in collagen before studying the more complex chemistry of the tissue.

Methods: The reaction between 0.6% glutaraldehyde and 6-AHA was studied by positive ion electrospray-mass spectroscopy. Untreated, locally treated and commercially produced explanted and non-implanted tissue were hydrolyzed under various conditions and analyzed both directly and after derivatization with 4-chlorophenylhydrazine, 4-bromophenacyl bromide and dansyl chloride by reverse-phase-high performance liquid chromatography-mass spectrometry.

Results: The mass spectral data obtained from the reaction of glutaraldehyde with 6-AHA showed the presence of alpha,beta unsaturated aldehydes and their further condensation products involving Michael reactions of glutaraldehyde, Schiff base cross-links and various cyclization products incorporating pyridinium and dihydropyridine ring structures. The only stable cross-link detected was an 'anabilysine'-like compound. Similar structures were present in the tissue, and anabilysine was identified by tandem mass spectrometry.

Conclusion: The results from the reaction of glutaraldehyde with 6-AHA agree with those published previously. The only detectable stable cross-link definitively identified in treated bioprosthetic tissue was anabilysine. No long-chain polymers of glutaraldehyde were detected.

How to cite: Southern, L. J., Hughes, H., Lawford, P. V., Clench, M. R., & Manning, N. J. (2000). Glutaraldehyde-induced cross-links: a study of model compounds and commercial bioprosthetic valves. The Journal of heart valve disease, 9(2), 241–249.

Background and aim of the study: Enhanced fixation of bioprosthetic tissue by both increased concentrations of glutaraldehyde (GA) and the introduction of additional cross-links with L-lysine significantly reduces calcification. We have previously reported that prolonged exposure to high-volume amino-compounds under warm, acidic conditions leads to thorough, non-rebounding GA detoxification. The aim of the present study was to prove that removal of excess GA can amplify the benefits of enhanced GA cross-linking with regard to bioprosthetic tissue calcification.

Methods: Porcine ascending aortas and leaflet tissue, and bovine pericardium were immediately fixed using three GA concentrations (0.2%, 1.0%, 3.0% (v/v)) for seven days at 4 degrees C. Samples were allocated to nine groups. Groups I to III received no further treatment (one at each GA concentration); groups IV to IX underwent an additional L-lysine interim step (48 h/37 degrees C/0.1 M) two days before completion of standard seven-day GA fixation; and groups VII to IX were additionally treated with a GA extraction process using high-volume urazole solution (acetic acid buffer, pH 4.5, 37 degrees C, one week) followed by NaBH4 reduction (2 days, 37 degrees C). Samples were implanted subcutaneously in rats (six per group) for six weeks. Tissue calcium was measured by atomic absorption spectrophotometry and examined histologically after von Kossa staining.

Results: Calcification was reduced in all three tissue types by enhanced cross-linking and by extraction of excess GA. Increasing the GA concentration from 0.2% to 3.0% led to a reduction in calcification of 11.5% (p = 0.074; Student's t-test) in leaflets; 63.6% (p <0.0001) in pericardium; and 17.5% (p = 0.034) in aortic wall tissue. The introduction of additional cross-links with L-lysine resulted in a significant reduction of calcium in all tissues (maximally 42.5%, p = 0.0003 in leaflets; 79.3%, p = 0.005 in pericardium; and 49.6%, p <0.0001 in aortic wall; Student's t-test). Optimal reduction in calcification could be achieved with the combined effect of 3.0% GA fixation, L-lysine enhancement and urazole detoxification. When compared with 0.2% GA-fixed tissue, calcification could be reduced by 99.1% in leaflets, 95.9% in pericardium, and 90.8% in aortic wall tissue (p <0.0001 for all tissue types; Student's t-test).

Conclusion: Removal of excess GA from fixed bioprosthetic tissue was capable of markedly improving the anti-calcific effect of enhanced GA cross-linking.

How to cite: Weissenstein, C., Human, P., Bezuidenhout, D., & Zilla, P. (2000). Glutaraldehyde detoxification in addition to enhanced amine cross-linking dramatically reduces bioprosthetic tissue calcification in the rat model. The Journal of heart valve disease, 9(2), 230–240.

Background and aim of the study: Mitral valve repair is superior to prosthetic valve replacement due to preservation of the subvalvular apparatus. We used cryopreserved homografts for mitral valve replacement in selected cases, in whom valve repair would not have been successful.

Methods: Cryopreserved homografts were used in 10 patients (four males, six females; mean age 47 +/- 8 years; range: 27-65 years), for either complete (n = 7) or partial (n = 3) mitral valve replacement. Surgery was indicated due to acute endocarditis (n = 3), stenosis (n = 4) or combined mitral valve disease (n = 3). Transesophageal echocardiography (TEE) was performed to determine correct homograft size; these values were compared with intraoperative measurements of valvular dimensions. The function of the implanted grafts was examined intraoperatively by TEE. Follow up included clinical examination, electrocardiography and echocardiography.

Results: All patients survived surgery. Intraoperative TEE revealed mild insufficiency (grade I) in six cases and no insufficiency in four. The papillary muscle-mitral annulus distance was the most reliable preoperative echocardiographic parameter to determine the required homograft. Mean pressure gradients were 3.2 +/- 0.7 mmHg for complete and 2.4 +/- 0.5 mmHg for partial homograft replacement. Sinus rhythm was present in all cases at discharge. Mean follow up was 24 months (range: 6-36 months). At six-month and one-year follow up, the pressure gradients had risen slightly to 3.4 +/- 0.6 mmHg (complete) and 2.8 +/- 0.6 mmHg (partial). To date, four patients had competent grafts, and six presented with an insufficiency (grade I). All patients had normal left ventricular function (EF 65 +/- 6%) at their last follow up; there were no signs of endocarditis during the follow up period.

Conclusion: Mitral homografts for valve replacement or repair are recommended in selected cases in whom conservative reconstruction techniques are not possible. The avoidance of long-term anticoagulation therapy and preservation of left ventricular geometry are clear advantages to other mitral valve prostheses.

How to cite: Gulbins, H., Kreuzer, E., Uhlig, A., & Reichart, B. (2000). Mitral valve surgery utilizing homografts: early results. The Journal of heart valve disease, 9(2), 222–229.

Background and aim of the study: Aortic valve replacement with cryopreserved human pulmonary or aortic valves (homografts) is an attractive alternative to the implantation of mechanical valves or bioprostheses, as anticoagulation can be avoided and a near-normal anatomy restored. However, few reports exist on the long-term follow up of patients with this type of valve.

Methods: Between 1990 and 1997, a total of 64 homografts were implanted in 62 adults (mean age 42 +/- 12 years) with non-endocarditic valve lesions (insufficiency, n = 16; stenosis, n = 20; combined lesions, n = 12; redo, n = 16). In total, 23 pulmonary grafts (PG) and 41 aortic grafts (AG) were used. Valves were obtained from the European Homograft Bank in Brussels. Two patients with aortic homografts were lost to follow up; the others were examined clinically and echocardiographically at yearly intervals (mean 3.6 +/- 2.0 years). Children aged less than 16 years (n = 21), and patients receiving a homograft due to endocarditis (n = 28) or during a Ross procedure (n = 16) were excluded from the study.

Results: Three patients (5%) died due to early postoperative complications (two with AG, one with PG). Three PG had to be explanted due to primary malfunction, and five (total 35%) during further follow up due to severe aortic insufficiency (at a mean of 3.3 +/- 1.8 years). In contrast, all AG were functioning at the end of the observation period (log rank test, p = 0.0001, chi-square test 13.9). The mean echocardiographic degree of regurgitation for PG was significantly higher than for AG (2.2 +/- 1 vs. 0.75 +/- 0.7, p <0.0001). The peak transvalvular gradient did not differ between groups (PG 12.3 +/- 9 mmHg vs. AG 16.7 +/- 10 mmHg, p = NS). In respect of perioperative parameters, patients with PG showed a significantly higher body temperature during the first seven postoperative days (37.3 +/- 0.6 degrees C vs. 36.8 +/- 0.3 degrees C, p = 0.003). All three patients with acute graft malfunction in long-term follow up had a perioperative febrile response without overt bacterial infection.

Conclusion: In contrast to grafts of aortic origin, pulmonary homograft valves should not be used for aortic valve replacement because of their high rate of malfunction, both acutely and chronically. Higher postoperative body temperatures should lead to further investigations of possible enhanced immunoreactions against pulmonary homografts.

How to cite: Naegele, H., Bohlmann, M., Döring, V., Kalmar, P., & Rödiger, W. (2000). Results of aortic valve replacement with pulmonary and aortic homografts. The Journal of heart valve disease, 9(2), 215–221.

Background and aim of the study: The preparation, banking and distribution of cryopreserved heart valves has been carried out at the European Homograft Bank (EHB) in Brussels without interruption since January 1989. We present an assessment of the Bank's activities during this 10-year period.

Methods: Heart valve donors aged <62 years form three categories: multiorgan donors with non-transplantable hearts; recipients of cardiac transplantation; and non-beating heart cadavers with a warm ischemia time of less than 6 h. Past history and biology are checked for transmissible diseases. Dissection, incubation in antibiotics and cryopreservation in 10% dimethylsulfoxide with storage in liquid nitrogen vapors (about -150 degrees C), and quality control are according to the standards of the Belgian Ministry of Health. Cryopreserved valves are shipped to the implantation centers in a dry shipper at about -150 degrees C.

Results: Between January 30th 1989 and December 31st 1998, 1,817 non-transplantable hearts and 12 excised semilunar valves were obtained. In total, 2,077 valves (1,032 pulmonary, 931 aortic and 13 mitral) were decontaminated, cryopreserved and stored in liquid nitrogen vapor (six more valves were refrigerated). In total, 1,515 valves were discarded at different stages of the protocol, the main causes of rejection being significant macroscopic lesions (68.2% aortic and 26.67% pulmonary). Inadequate excision at procurement (10.37% pulmonary), persistent contamination after antibiotics (5.6%) and positive serology for hepatitis B and C and Q fever (5.4%) were other frequent causes for rejection. Among the 2,117 accepted valves, 1,398 were graded first and 719 second choice, mainly on the basis of morphology. In total, 2,090 cryopreserved valves and one refrigerated valve were implanted in 39 institutions between May 1989 and December 1998. Of requests, 10.02% could not be satisfied. In total, 967 pulmonary valves were implanted in the right ventricular outflow tract (RVOT); 424 during a Ross procedure, and 76 in the left ventricular outflow tract (LVOT). Of the aortic valves, 732 were implanted in the LVOT and 266 in the RVOT. Mitral homografts were used for tricuspid valve replacement in two cases, and in the mitral position in seven. Complications at distribution and thawing included 10 bag ruptures and 16 transversal conduit wall fractures. Of the valves shipped, 317 (13.16%) were not used and were returned safely in the dry shipper. Comparison of distribution rates in the first 5.5 and last 4.5 years of EHB activity shows: (i) a significant increase in pulmonary valve implantations in the RVOT (from 71.95% to 81.95%); and (ii) a marked increase (265%) in pulmonary homograft implantations as part of a Ross operation, and a significant decrease (28%) in aortic homograft implantation in the LVOT.

Conclusion: While macroscopic lesions of procured aortic valves remain the most frequent and unavoidable cause of homograft rejection during quality control, the high percentage of inadequate surgical heart valve excision should be corrected. The rates of bacterial contamination and positive serology seem acceptable. Storage and shipping of cryopreserved homografts in liquid nitrogen vapor permits them to be spared very efficiently. The increasing use of pulmonary valves for RVOT reconstruction either in congenital heart disease or as part of the Ross procedure compensates for the limited availability of good quality aortic valves.

How to cite: Goffin, Y. A., Van Hoeck, B., Jashari, R., Soots, G., & Kalmar, P. (2000). Banking of cryopreserved heart valves in Europe: assessment of a 10-year operation in the European Homograft Bank (EHB). The Journal of heart valve disease, 9(2), 207–214.

Background and aim of the study: Cryopreserved valve homografts often fail in infants. Controversies are ongoing concerning the relative contributions of cryopreservation variables, immune responses, cellular viability, and durability of the extracellular matrix to the mode of tissue failure.

Methods: Tissues to be examined for patterns of ice crystal distribution were cryopreserved. Tissue water was substituted with methanol and the tissues cryopreserved conventionally using dimethylsulfoxide, after which they were warmed and processed for light or electron microscopy. Selected specimens were vitrified to prevent ice crystal formation, cryopreserved, and subsequently warmed and processed for light and electron microscopy.

Results: Cryosubstitution of conventionally cryopreserved heart valves, while still frozen, demonstrated extensive extracellular ice formation, with smaller crystals in the ventricularis than in either the spongiosa or fibrosa. Extracellular ice formation was prevented by vitrification, a process in which the biological system is stabilized as an amorphous solid in the absence of crystalline ice.

Conclusion: It is proposed that the extensive ice formation observed in conventionally cryopreserved heart valves may cause extracellular matrix damage that predisposes the valves to calcification. Future studies will assess the above hypothesis by comparison of conventional and ice-free (vitrification) cryopreservation methods in animal models of calcification.

How to cite: Brockbank, K. G., Lightfoot, F. G., Song, Y. C., & Taylor, M. J. (2000). Interstitial ice formation in cryopreserved homografts: a possible cause of tissue deterioration and calcification in vivo. The Journal of heart valve disease, 9(2), 200–206.

Background and aim of the study: Pulmonary autograft replacement of the aortic valve (the Ross procedure) is reliable and durable; however, geometric mismatch of the autograft and systemic outflow tract may lead to poor results. Manipulation of the aortic annulus and sinotubular diameters to match the autograft can prevent geometric mismatch, and improve results.

Methods: Annuloplasty and/or aortoplasty were combined with the Ross procedure in 26 of 44 patients (median age 42.5 years; range: 3 days to 62 years) undergoing surgery between April 1994 and July 1998. Plication of the aortic annulus at either two or three of the commissures was done in five cases, aortic annulus fixation with an external pericardial pledget incorporated in the proximal suture line in 12 cases, and tailoring aortoplasty in nine patients.

Results: There was one operative death. Two patients required reoperation; one for progressive autograft dysfunction and one for homograft dysfunction. Annular fixation was performed on the patient requiring reoperation for autograft dysfunction. Doppler echocardiography during the follow up (median 9 months; range: 1-50 months) revealed 10 patients with trace 1+ and one patient with 2+ aortic insufficiency. Trace 1+ and 2+ aortic stenosis were present in one patient each. None of the patients undergoing commissural plication had significant regurgitation or stenosis. Both patients with stenosis underwent annular fixation. Aortoplasty was associated with 1+ insufficiency in two patients.

Conclusion: Prevention of geometric mismatch between the autograft and systemic outflow tract at the annulus and sinotubular junction by plication techniques allows better performance of the autograft, and extends the Ross procedure to patients who otherwise may be unable to undergo such surgery. Fixation may provide similar benefit, but appears to be more susceptible to insufficiency and stenosis.

How to cite: Klena, J. W., Shweiki, E., Mahaffey, H. W., Woods, E. L., Benoit, C. H., & Gilbert, C. L. (2000). Annuloplasty and aortoplasty as modifications of the Ross procedure for the correction of geometric mismatch. The Journal of heart valve disease, 9(2), 195–199.

Background and aim of the study: Objective Performance Criteria (OPC) were established to compare a new heart valve prosthesis with fixed standards of linearized complication rates for morbid events: thromboembolism, thrombosis, hemorrhage, leakage and endocarditis. Although the pulmonary autograft operation provides optimal hemodynamic performances, the morbidity of both the autograft and homograft remain topics of controversy.

Methods: Valve-related morbid events and echocardiography in 109 patients who have undergone the Ross operation since 1991 were evaluated at annual follow up examination (mean 2.8 years; range: 1 month to 8 years). Linearized rates (number of events per 100 years patient exposure) were calculated to establish the safety and efficacy of this operation (288.7 years cumulative patient-years).

Results: Three patients died perioperatively (2.8%); two patients were reoperated due to autograft incompetence (1.8%, both valve repairs). No patient is currently on anticoagulation therapy, and no events of thromboembolism, valve thrombosis or bleeding were observed during follow up. Two patients had homograft endocarditis but were asymptomatic with moderate incompetence at the last follow up examination. There was no significant increase in aortic incompetence (AI) or pulmonary incompetence (PI) between discharge and follow up (AI, 0.4 +/- 0.5 versus 0.6 +/- 0.6; PI, 0.2 +/- 0.4 versus 0.4 +/- 0.6). In comparing the OPC (events per patient-year) for the Ross operation with those for tissue and mechanical valves, the results were: thromboembolism 0% (tissue 2.5%, mechanical 3%), valve thrombosis 0% (0.2% and 0.8%), all bleeding 0% (1.4% and 3.5%), major bleeding 0% (0.9% and 1.5%), all leakage 0.7% (1.2% and 1.2%), major leakage 0.7% (1.2% and 1.2%) and endocarditis 0.7% (1.2% and 1.2%).

Conclusion: The pulmonary autograft procedure provides optimal hemodynamics and echocardiographic performance, and low valve-related complication rates; thus, the OPC for tissue and mechanical heart valve prostheses can be fulfilled by this technically demanding operation. These results confirm that the autograft is an ideal aortic valve replacement device.

How to cite: Moidl, R., Simon, P., Aschauer, C., Chevtchik, O., Kupilik, N., Rödler, S., Wolner, E., & Laufer, G. (2000). Does the Ross operation fulfil the objective performance criteria established for new prosthetic heart valves?. The Journal of heart valve disease, 9(2), 190–194.

Background and aim of the study: Although pulmonary autografts offer advantages over aortic homografts, they may also carry additional risks. We reviewed the interim results of a prospective randomized trial of autograft versus homograft aortic valve replacement (AVR) to determine if the greater complexity of the autograft insertion is justified, particularly with regard to time-related hemodynamic function.

Methods: A total of 182 patients (82% male, 18% female; mean age 37.2 +/- 14.3 years; range: 2-64 years) with isolated aortic valve disease were randomized to pulmonary autograft (group A, n = 97) or aortic homograft (group H, n = 85); 42% had previous aortic valve surgery and 19% had native or prosthetic valve endocarditis. Follow up included annual outpatient visits and echocardiography.

Results: Autograft AVR required longer cross-clamp (41%) and bypass (43%) times, but did not result in significantly more bleeding, longer recovery or more complications. One 30-day death occurred in group A (1%), and three deaths in group H (4%). Median follow up was 33.9 months (range: 1-61 months). There was one late death in each group, three reoperations in group A (all for pulmonary homografts), and three in group H (including two aortic homograft reoperations, both in children). There were no autograft reoperations. There were no other valve-related events. At 48 months, actuarial survival and reoperation-free survival rates were 97.8% and 94.2% in group A, and 95.3% and 87.7% in group H (p = NS). Echocardiography showed near-perfect function in all autografts, but early signs of subclinical dysfunction in many homografts.

Conclusion: Both autograft and homograft AVR are safe and produce good intermediate-term results. Early homograft degeneration appears to favor autografts in children. The echocardiographic findings may translate into superior long-term autograft durability and hemodynamics.

How to cite: Aklog, L., Carr-White, G. S., Birks, E. J., & Yacoub, M. H. (2000). Pulmonary autograft versus aortic homograft for aortic valve replacement: interim results from a prospective randomized trial. The Journal of heart valve disease, 9(2), 176–189.

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How to cite: Ross D. N. (2000). The pulmonary autograft: the Ross principle (or Ross procedural confusion). The Journal of heart valve disease, 9(2), 174–175.