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Biomedical subjects

A Mazzucco

Publications and source records attributed to A Mazzucco.

At least 109 records · Page 6Linked to original sources
PubMed1993

Severe ischemic left ventricular failure: coronary operation or heart transplantation?

Severe left ventricular failure in ischemic heart disease may contraindicate conservative surgical procedures. To redefine therapeutic indications, the clinical and angiographic data of 143 patients (137 men and 6 women) with ischemic heart disease and a left ventricular ejection fraction less than 0.30 who were seen by us between June 1985 and December 1990 were retrospectively analyzed. Patients were divided into three groups according to therapy: medical only, 72 (group 1); myocardial revascularization, 20 (group 2); and heart transplantation, 51 (group 3). Clinical status was poorer in group 3, with congestive heart failure as predominant symptom; angina was more frequent in group 2. No difference was noted in hemodynamic variables. Four early deaths (20.0%) occurred in group 2 and 7 (13.7%) in group 3. Follow-up ranged from 1 to 64 months (mean, 22 +/- 19 months), with an actuarial survival of 28% +/- 9%, 80% +/- 8% and 82% +/- 5% at 5 years in groups 1, 2, and 3, respectively. Even though postoperative New York Heart Association class was better in group 3 (1.0 versus 2.3 in group 2; p < 0.01), the difference in survival was not significant. Although in patients with ischemic heart disease and low left ventricular ejection fraction heart transplantation offers the best clinical results, considering the donor shortage, we conclude that myocardial revascularization may still be performed with good midterm results.

Actuarial Analysis↗
PubMed1993

Mechanical assist device for right ventricular failure after acute aortic dissection.

Acute myocardial ischemia and infarction due to retrograde coronary artery dissection are uncommon complications after ascending aortic dissection. A case of acute aortic dissection with massive right ventricular failure successfully treated by replacement of the ascending aorta and postoperative right ventricular mechanical support is presented. Although mechanical assistance may be hazardous after ascending aortic replacement, because of the need of anticoagulation, it represents a valid therapeutic option when severe right ventricular failure due to acute myocardial infarction ensues.

Acute Disease↗
PubMed1993

Application of fresh and cryopreserved homografts harvested from transplant patients for correction of complex congenital heart disease.

In recent years, the use of homograft tissue in cardiac surgery has increased so that supply is limited. Since October 1990, aortic and/or pulmonary valves were collected from 17 transplant recipients at the Department of Cardiovascular Surgery of the University of Padova Medical School (11 male, 6 female, mean age 43.4 years, range 11 months to 61 years). The indications for transplant were dilated cardiomyopathy in 7, and end-stage ischemic heart disease in the remaining 10 patients. Twelve such valves have been subsequently reimplanted either as fresh or as cryopreserved valved homografts in the repair of different forms of congenital heart disease, by means of different tailoring techniques (7 male, 5 female; mean age 4.8 years [range 1 day to 18 years]; transposition of the great arteries = 5 cases; tetralogy of Fallot = 3 cases; hypoplastic left heart syndrome = 2 cases; double outlet right ventricle = 1 case; truncus arteriosus = 1 case). Overall, early mortality was 25%. None of these deaths could be related to the use of homografts. There have been no instances of valve related complications among nine patients surviving surgery at a mean follow-up of 11 months. All patients having heart explanted should be regarded as potential sources for aortic and pulmonary homografts.

Adolescent↗
PubMed1993

Mechanical support for decompression of the left ventricle in repair of ischemic cardiac rupture.

Acute cardiac rupture is often a lethal complication of transmural myocardial infarction. A case of successfully treated left ventricular free wall rupture is described. Preoperative hemodynamic stabilization was achieved by intraaortic balloon counterpulsation. A BioMedicus left ventricular assist device was used intraoperatively and postoperatively to obtain long-term intraventricular decompression to allow for suture repair of friable myocardium.

Aged↗
PubMed1993

Effects of ischemia on sarcoplasmic reticulum and contractile myofilament activity in human myocardium.

The effects of global ischemia on the contractile system and on sarcoplasmic reticulum (SR) function were studied by measuring the isometric tension and the SR Ca2+ release activity of chemically skinned cardiac fiber preparations from seven patients undergoing open-heart surgery. Ten minutes of ischemia caused 1) a decrease in the myofilament sensitivity to Ca2+ (expected Ca2+ concentration giving half-maximal tension; from 0.69 +/- 0.04 to 1.38 +/- 0.06 microM, n = 7) and in the cooperativity index (Hill coefficient; from 2.61 +/- 0.45 to 0.92 +/- 0.15, n = 7), 2) a decrease in myosin light chain phosphorylation, and 3) a 300% increase in the threshold caffeine concentration for SR Ca2+ efflux channel activation, with a 30% reduction in the rate of Ca2+ release by caffeine at threshold concentrations and a 23% reduction in the rate of release by 20 mM caffeine. After preincubation with 5 microM trifluoperazine, a calmodulin antagonist, the caffeine threshold of ischemic and control cardiac muscle became comparable. Most changes were reversed by reperfusion, while the caffeine threshold was still two times greater than control. These results indicate that ischemia caused alterations of the cardiac muscle contractile apparatus and the SR that were reversed only after reperfusion.

Actin Cytoskeleton↗
PubMed1993

Fatal obstruction of the left ventricular outflow tract caused by low-profile bioprostheses in the mitral valve position.

Two cases of fatal left ventricular outflow tract obstruction following mitral valve replacement with low-profile bioprostheses are described. This unfortunate experience shows that correct orientation of the prosthesis is mandatory also when using low-profile bioprosthetic valves to avoid this complication, particularly in patients with a small left ventricular cavity.

Aged↗
PubMed1993

Reoperation in patients with a bioprosthesis in the mitral position: indications and early results.

Our experience with 221 patients undergoing a first reoperation for bioprosthesis failure in the mitral position is reviewed. Most, (196, 89%) were reoperated because of structural valve deterioration, 16 (7%) had periprosthetic leak and nine (4%) had prosthetic endocarditis. Operative mortality (23 patients overall, 10.4%) was significantly higher in those patients who were in NYHA functional class IV or had impaired left ventricular function, in those reoperated because of prosthetic endocarditis and those undergoing emergency reoperation. Those patients who had structural valve deterioration, good left ventricular function and who were reoperated electively had the lowest operative risk. With increasing experience and the use of standardized surgical techniques, the results of reoperation for bioprosthetic failure have improved considerably in recent years. A further reduction in operative risk can be expected with better patient selection, obtained through more careful non-invasive assessment of valve performance to detect the initial signs of bioprosthetic failure.

Adolescent↗
PubMed1993

Ball fracture with the 6120-model Starr-Edwards mitral valve prosthesis occurring late after implantation.

The Starr-Edwards (S-E) mitral valve, Model 6120, has been widely used in the last three decades. Fatty infiltration and subsequent damage of the silastic ball, a phenomenon termed ball variance, has been described only in the first generation aortic ball-valve prostheses, used until 1965. A case of partial ball fracture in a 6120-Model S-E mitral valve prosthesis, occurring 27 years after implantation and presenting with thromboembolism and progressive valve dysfunction, is described.

Follow-Up Studies↗
PubMed1993

Discrete subaortic stenosis. Operative age and gradient as predictors of late aortic valve incompetence.

Between January 1969 and May 1990, 100 patients were operated on for discrete subaortic stenosis. Three patients died in the perioperative period. Patients with intrinsic lesions, prosthetic replacement, or extensive operative remodeling of the aortic valve were excluded from the analysis. The 67 remaining patients had a median follow-up of 62 months. Preoperatively, 8 patients had aortic valve competence, 51 had mild incompetence, and 8 patients moderate aortic valve incompetence. At follow-up mild incompetence persisted in 27 and moderate incompetence in 6 patients. In 1 patient it worsened from no incompetence to mild and in another patient from mild to moderate. The probability of aortic incompetence at follow-up was significantly and simultaneously related (multivariate ordinal logistic model) to (1) older age at operation (logarithm of months, p = 0.007), (2) higher preoperative gradient (third power of milligrams of mercury, p = 0.0004), (3) preoperative cardiomegaly (p = 0.04), and (4) surgical myectomy (p = 0.002). There was an interaction between age and gradient (p = 0.03). Two nomograms are proposed as a generalizable aid to decision making. The data support the policy of early repair of subaortic stenosis.

Adolescent↗
PubMed1993

Pulmonary atresia, intact ventricular septum, and Ebstein anomaly of the tricuspid valve. Anatomic and surgical considerations.

Pulmonary atresia with intact ventricular septum is a disorder that involves the whole right ventricle. An associated Ebstein deformity of the tricuspid valve is found in 10% of the cases, further complicating the anatomy and the function of the right ventricle. From January 1966 to December 1990, pulmonary atresia, intact ventricular septum, and Ebstein deformity of the tricuspid valve were observed in 11 cases in our institution; four of them were necropsy findings and the remaining seven were patients treated surgically. Of the latter, two were boys and five were girls (age range 1 day to 18 days). Two patients were managed by pulmonary valvotomy, three by systemic-pulmonary artery shunt, and two had a combination of the two. Operative mortality was 57%. Eight hearts were available for morphologic study. All had viscero-atrial situs solitus, D-loop ventricular structure, and normally related great arteries. A correlation between the degree of tricuspid valve dysplasia and right ventricular cavity size was observed in all. Furthermore, in five cases the anterior leaflet of the tricuspid valve obstructed the right ventricle at the ostium infundibuli level. In two of our surgical patients, a protruding anterior tricuspid valve leaflet was identified and excised and both patients survived. Ebstein anomaly of the tricuspid valve further complicates surgical management and outcome of pulmonary atresia and intact ventricular septum. Potential obstruction at the ostium infundibuli level should always be considered during repair. Various degrees of right ventricular inlet dysplasia, always present in this complex, may contraindicate an anatomic correction. In these cases a modified Fontan-type procedure should be considered as a valid surgical option.

Abnormalities, Multiple↗
PubMed1993

Long-term results of mitral commissurotomy.

Between January 1968 and December 1989, 280 patients underwent conservative surgical treatment for pure mitral stenosis. Closed commissurotomy was utilized in 134 patients, with a mean age of 38 +/- 11 years and a mean valve area of 1.0 +/- 0.29 cm2. Open commissurotomy was performed in 146 older patients (mean age 44 +/- 11 years) with a mean valve area of 0.9 +/- 0.3 cm2. The perioperative mortality was 3% in closed procedures and 3.4% in open procedures. Surviving patients were evaluated by questionnaires or phone interviews, and 129 patients were examined by two-dimensional echocardiography with the purpose of analyzing long-term results. Follow-up was 95% complete (Grunkemeier-Starr method), with a median of 18 years in patients with closed commissurotomy and 6.6 years in patients with open commissurotomy. The actuarial survival at 21 years was 60.8% (70% confidence limits 55% to 66%) in patients having closed commissurotomies and 60.6% (70% confidence limits 49% to 71%) at 22 years in patients having open commissurotomies. The "effective palliation" rate, defined by clinical and echocardiographic criteria, was 47% at 15 years and 15% at 20 years. We conclude that mitral commissurotomy is the procedure of choice in pure mitral valve stenosis and should be applied early. When performed in patients aged less than 40 years, a 78% (70% confidence limits 72% to 84%) survival at 18 years and 67% "effective palliation" at 15 years were observed. The closed valvotomy results of our study support the present trend toward use of percutaneous balloon valvotomy.

Adolescent↗
PubMed1992

A new, noninvasive method to monitor the aging of bioprosthetic valves in the mitral position.

Bioprosthetic valves undergo a tissue degeneration of unpredictable onset and amount. This process alters the structure and function of the valve and consequently shortens its lifespan. The echocardiographic technique usually used in the follow-up of these patients does not provide accurate information concerning the amount of prosthesis tissue degeneration. A new technique has been developed based on the spectral analysis of the first heart sound, which enables the evaluation of prosthetic leaflet stiffness. The Young's modulus (E) and stress (s) of the valve leaflets were derived as functions of the inner diameter of the heterograft and its primary vibration frequency, which can be obtained from the frequency spectrum of the first heart sound. Thirty-six patients with a mitral bioprosthetic valve were studied. Fifteen had thickening or calcification, or both, of the valvular leaflets at echocardiographic examination. In patients with a normal valve, E and s showed a good correlation with the duration of implantation (r = 0.909, p < 0.001; and r = 0.828, p < 0.001; respectively). Patients with abnormal leaflets had values of E and s that were greater than the theoretical values expected for their duration of implantation. The procedure is sensitive, accurate and easy to perform, and enables monitoring of the aging of the prosthetic valve and early identification of valve tissue degeneration. Together with echocardiography, this procedure yields a more complete evaluation of prosthetic valves for the follow-up of patients.

Aged↗
PubMed1992

The Meadox-Gabbay pericardial xenograft: failure of the unicusp principle.

Durability of a new bioprosthesis, the Meadox-Gabbay unileaflet pericardial xenograft, was evaluated by reviewing a series of 12 patients who received this device in the mitral position from 1983 to 1985. Bioprosthetic failure necessitated reoperation in 5 patients 21, 22, 53, 66, and 81 months after placement. Three patients died of cardiac failure after 31, 52, and 70 months; no postmortem examinations were done. In 2 of the 3 patients, an echocardiographic study had shown signs of valvular dysfunction. Pathological examination of five available explants revealed the presence of redundancy and stretching of the single pericardial leaflet in all of them; in one, this lesion alone caused severe prosthetic incompetence. Other pathological findings included cusp and commissural calcification and commissural tears with or without calcification. Histologic examination and electron microscopy showed intrinsic calcification involving both collagen bundles and cellular debris and various degrees of collagen disruption. In this limited series of patients, the Meadox-Gabbay pericardial xenograft demonstrated various modes of failure that markedly impair its durability and render it unsuitable as a cardiac valve substitute.

Adult↗
PubMed1992

Annular enlargement during aortic valve replacement: preliminary results with a simplified technique.

A simplified technique has been used to enlarge the aortic annulus in a series of 13 patients undergoing aortic valve replacement. The procedure basically consists of extending the aortotomy incision into the aortic annulus by dividing the commissure between the left and noncoronary sinuses, without involving the anterior mitral leaflet. Wide opening of the commissure is obtained and the resulting defect is closed, preferably using a patch of bovine pericardium sutured to the mitral annulus and aortic wall. This technique is simple, reproducible, avoids opening of the left atrium (reducing the potential bleeding sites), allows insertion of a prosthesis at least two sizes larger than the original annulus, and is also applicable in cases of mitral-aortic valve replacement. Our preliminary results are satisfactory and seem to demonstrate that in many patients, even in the young age group, more complex procedures are often unnecessary when enlargement of the aortic annulus is required.

Adult↗
PubMed1992

Contractile properties and Ca2+ release activity of the sarcoplasmic reticulum in dilated cardiomyopathy.

BACKGROUND: We performed a comparative study on Ca2+ release activity of the sarcoplasmic reticulum and calcium sensitivity of contractile apparatus of chemically skinned myocardial fibers obtained from four nonfailing human hearts and 13 excised hearts from patients with idiopathic dilated cardiomyopathy. METHODS AND RESULTS: Ca2+ sensitivity of contractile apparatus was studied by following the isometric tension developed by chemically skinned myocardial fibers challenged with solutions of decreasing pCa. Ca2+ release from sarcoplasmic reticulum was monitored indirectly by measurement of the isometric tension developed by skinned fibers challenged with caffeine. We observed no significant difference of Ca2+ sensitivity and cooperativity between normal myocardium (pCa50 = 6.00 +/- 0.05; Hill coefficient, nHill = 2.07 +/- 0.10) and dilated cardiomyopathy (pCa50 = 6.03 +/- 0.07; nHill = 2.72 +/- 0.30) when the fibers were stretched to 130% of the resting length. We also found that both in normal myocardium and dilated cardiomyopathy, stretching to 150% of the resting length increased the Ca2+ sensitivity of the contractile system; pCa50 = 6.21 +/- 0.01 and 6.13 +/- 0.04 in normal and dilated cardiomyopathy, respectively, whereas in dilated cardiomyopathy there was a decrease of Hill coefficient with stretching that was not observed in the control group. The caffeine threshold in idiopathic dilated cardiomyopathy was markedly increased compared with the control group, 1.94 +/- 0.27 mmol/l and 0.29 +/- 0.04 mmol/l caffeine, respectively, whereas there were no significant differences in the extent and rate of caffeine-induced Ca2+ release. CONCLUSIONS: These results indicate that in idiopathic dilated cardiomyopathy there is no alteration of contractile and regulatory proteins; on the contrary, the gating mechanism of the Ca2+ release channel of sarcoplasmic reticulum is abnormal, suggesting a possible involvement of the excitation-contraction coupling in the pathogenesis of this disease. It should also be taken into account, however, that the increased caffeine threshold in dilated cardiomyopathy would be a result of the enhanced resistance to the skinning procedure secondary to the modification of lipid species and/or content in sarcoplasmic reticulum membrane.

Adolescent↗
PubMed1992

Original expectations of the Hancock valve and 20 years of clinical reality.

The standard (glutaraldehyde-preserved) Hancock porcine bioprosthesis was introduced into clinical practice in order to provide surgeons with a cardiac valve substitute which would be nonthrombogenic and therefore would not require anticoagulation, and would be durable, anatomically suitable, and noiseless. In the present report we have reviewed our long-term experience with Hancock porcine valve recipients in order to verify the original expectations of this bioprosthesis have been met.

Adolescent↗