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Biomedical subjects

A Milano

Publications and source records attributed to A Milano.

At least 127 records · Page 7Linked to original sources
PubMed1988

Hancock bioprosthetic valve failure: causes, and results of reoperation.

Between March 1970 and the end of December 1986, 180 porcine valve recipients underwent reoperation at our institution because of bioprosthetic failure. Of these patients, 126 (70.0%) had mitral bioprosthesis replacement (MBR), which was necessitated because of primary tissue failure in 107 cases, prosthetic valve endocarditis in eight cases, and paravalvular leakage in eleven cases. Forty-six patients (25.5%) had aortic bioprosthesis replacement (ABR), owing to primary tissue failure in 37 cases, endocarditis in six cases, and paravalvular leakage in three cases. The remaining eight patients (4.5%) all underwent double (mitral and aortic) bioprosthesis replacement (DBR) because of primary tissue failure. In a total of 152 patients who underwent reoperation for primary tissue failure, the hospital mortality was 6.5% for the MBR group, 8.0% for the ABR group, and 0% for the DBR group (mean, 6.5%). In those 14 patients who required reoperation owing to endocarditis, the hospital mortality was 75% for the MBR group and 50% for the ABR group (mean, 64%). In another 14 patients who underwent reoperation because of paravalvular leakage, the hospital mortality was 9% for the MBR group and 0% for the ABR group (mean, 7%). Morphologic studies of the explanted valves revealed that tissue calcification is the most frequent cause of primary tissue failure in Hancock-valve recipients. Calcification leads to cusp stiffening with stenosis or to cuspal and commissural rupture with incompetence. Usually, primary tissue failure causes progressive dysfunction that allows for elective reoperation, which is associated with a low mortality; rarely, however, porcine xenograft failure can occur acutely and require emergency operation, which is associated with a significantly higher risk. Such operation was necessary in nine (6%) of our patients with primary tissue failure and resulted in four deaths (44%); conversely, elective reoperation was done in 143 patients with other primary tissue failure (94%) and resulted in six deaths (4%) (p<0.001). Our long-term experience with the Hancock bioprosthesis confirms that this valve's durability is limited. Therefore, we believe that the indications for the use of porcine bioprostheses should be restricted, until consistent data become available concerning the durability of the new generation of prosthetic valves.

Journal Article↗
PubMed1988

Tricuspid atresia versus other complex lesions. Comparison of results with a modified Fontan procedure.

Several modifications of the Fontan principle are currently applied to the treatment of tricuspid atresia with low mortality. The use of these modifications in other malformations has most frequently been associated with less satisfactory results. At our institution, from June 1977 to October 1986, 35 consecutive patients, whose ages ranged from 8 months to 20 years (median age 3.4 years), underwent a modified Fontan procedure. Twenty patients with a median age of 3.2 years (group I) having tricuspid atresia (16 patients) or hypoplastic right heart syndrome (four patients) were treated by means of a right atrium-pulmonary artery anastomosis (12 patients) or right atrium-subpulmonary chamber connection (eight patients). Fifteen patients (group II) with a median age of 3.6 years, having a single left ventricle (10 patients), left atrioventricular valve hypoplasia or atresia (three patients), or double-outlet right ventricle (two patients), underwent right atrium-pulmonary artery anastomosis, together with a repositioning of the atrial septum to the right of the right atrioventricular valve, which thus left intact the inlet to the ventricle(s). The operative mortality rate was 25% in group I and 0% in group II. One patient in group I and one in group II died late postoperatively. All the 28 survivors are free of symptoms 3 months to 9 years after correction. According to our results, low risk can be associated with modified Fontan procedures in the treatment of complex heart malformations other than tricuspid or pulmonary atresia. Preserving the integrity of the entire inlet to the ventricle(s) by repositioning the interatrial septum, as done in group II malformations, might be helpful in improving the quality of the repair.

Adolescent↗
PubMed1987

Post bending of the polypropylene flexible stent in mitral Hancock bioprostheses.

The occurrence of stent post deformity was investigated in 38 consecutive, polypropylene flexible-stented Hancock porcine bioprostheses (PB) recovered from the mitral position because of early postoperative death or late tissue failure. The degree of deformity was assessed for each explant by calculating the triangular area obtained by projecting the apex of the stent posts on a plane and comparing it with the same area calculated for unimplanted PBs of comparable size. A significant stent deformity (reduction of the triangular area greater than 40%) was observed only in 6 PBs explanted because of tissue failure after a mean function time of 69.6 +/- 28 months. In these PBs, scanning electron microscopy of the bare surface of the stent at the point of maximal flexion showed cracks 0.7-1 microns large, which represent the morphological substrate of the so-called "creep" of polypropylene. Inward stent post bending may occur after implantation in mitral PBs and when severe, it corresponds to a definite ultrastructural plastic deformity of polypropylene.

Animals↗
PubMed1987

Long-term durability of the Hancock porcine bioprosthesis following combined mitral and aortic valve replacement: an 11-year experience.

Long-term evaluation of patients undergoing combined mitral and aortic valve replacement (MVR + AVR) with a porcine bioprosthesis provides the opportunity for a direct comparison of the durability of the mitral versus the aortic porcine bioprosthesis in the same patient. From 1970 to 1983, 71 patients underwent MVR + AVR with Hancock porcine bioprostheses. There were 46 men an 25 women ranging in age from 21 to 64 years (mean, 47.5 +/- 5 years). Sixteen patients (22.5%) died at operation. The survivors were followed from 0.2 to 11.5 years (mean, 5.7 +/- 3 years). Duration of follow-up was 313 patient-years and was 100% complete. Overall late mortality was 6.7 +/- 1.4% per patient-year (linearized incidence), and actuarial survival was 54.2 +/- 8% at 11 years. Endocarditis occurred in 4 patients (linearized incidence of 1.3 +/- 0.6% per patient-year); thromboembolic events were sustained by 4 patients (linearized incidence of 1.3 +/- 0.6% per patient-year); the event was fatal in 1 patient. Actuarial freedom from thromboembolism was 90 +/- 4.8% at 11 years. Reoperation for primary tissue failure was performed in 11 patients (linearized incidence of 3.5 +/- 1% per patient-year) with no deaths; in 7 patients both bioprostheses were explanted, and in 4, only the mitral bioprosthesis was replaced. The durability of explanted aortic and mitral porcine bioprostheses was not significantly different, and the evaluation of seven pairs of explanted aortic and mitral bioprostheses showed similar amounts of calcification. Actuarial freedom from reoperation because of primary tissue failure was 44.6 +/- 13.7% at 11 years.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1987

Early mechanical failures of the Hancock pericardial xenograft.

From August 1981 to July 1984, a total of 97 Hancock pericardial xenografts were implanted in 84 patients, whose ages ranged from 13 to 75 years (mean 55.7 +/- 13). Mitral value replacement was performed in 17, aortic valve replacement in 54, and mitral-aortic valve replacement in 13. Operative survivors were reevaluated from July to September 1985. Cumulative duration of follow-up is 167 patient-years (range 0.5 to 4.1 years), and follow-up is 99% complete. The overall late mortality (at 4 years) is 3.6% +/- 1.4% per patient year, and the actuarial survival rate is 95.4% +/- 3% for aortic valve replacement, 74.7% +/- 16.5% for mitral valve replacement, and 67.1% +/- 20.7% for mitral-aortic valve replacement. One patient sustained a thromboembolic event after mitral valve replacement, but no such complications occurred after aortic or mitral-aortic valve replacement. Actuarial freedom from embolism at 4 years is 100% for aortic and mitral-aortic valve replacement and 93.3% +/- 6.4% for mitral valve replacement. Reoperation for Hancock pericardial xenograft dysfunction was performed in seven patients (five aortic and two mitral-aortic). In the aortic valve replacement group the causes were endocarditis in one, paravalvular leak in one, and primary tissue failure in three; all survived reoperation. The two patients with mitral-aortic valve replacement required reoperation because of primary tissue failure of both Hancock pericardial xenografts, and one died. All values explanted because of primary tissue failure showed commissural tears causing severe prosthetic regurgitation. Calcium deposits were severe in one and mild but unrelated to the cusp rupture in another. Collagen disarray was seen only at the site of the tears, whereas the collagen structure was well preserved in the intact parts of the cusps. Four patients with aortic valve replacement and one with mitral valve replacement show evidence of Hancock pericardial xenograft failure and are awaiting reoperation. The actuarial freedom from primary tissue failure at 4 years is 74.3% +/- 9.8% for aortic and 78.9% +/- 13.2% for mitral Hancock pericardial xenografts. At medium-term follow-up, the Hancock pericardial xenograft has shown poor durability and an extremely high rate of early mechanical failure, especially in the aortic position. These observations suggest the need for a close follow-up of Hancock pericardial xenograft recipients and possibly elective reoperation in asymptomatic patients with clinical evidence of prosthetic failure. These results have led us to discontinue the clinical use of this pericardial xenograft.

Adolescent↗
PubMed1987

Dissecting cuspal hematomas. A rare form of porcine bioprosthetic valve dysfunction.

Large dissecting cuspal hematomas (DCHs) were present in six (3%) of 193 porcine bioprostheses (PBs) explanted at reoperation. In four mitral PBs, the DCHs contributed to valve dysfunction; in one aortic PB, DCH was the only determinant of failure, causing stenosis by cusp thickening and rigidity. In another mitral PB, DCHs were occasionally found in the setting of valve incompetence due to commissural tears. While confirming that DCHs are a potential but infrequent cause of PB failure, these observations demonstrate that they may involve PBs implanted both in mitral and aortic position and might be a complication of anticoagulation.

Adult↗
PubMed1986

A familial visceral myopathy with dilatation of the entire gastrointestinal tract.

We are reporting a new kindred in which familial visceral myopathy was identified in four siblings. There was no other symptomatic case identified in this 75-member, four-generation family, suggesting an autosomal recessive inheritance. All patients had recurrent symptoms of intestinal obstruction, and 3 died from malnutrition. Gastrointestinal lesions showed marked dilatation of the entire digestive tract from the esophagus to the rectum, which is different from other types of familial visceral myopathies. Microscopic examination of the gastrointestinal smooth muscle showed degeneration and increased fibrosis indistinguishable from other types of familial visceral myopathy.

Adult↗
PubMed1986

The use of intraluminal prosthesis in the surgical management of aortic dissection.

The treatment of acute aortic dissection requires expeditions and reproducible operations aimed at avoiding rupture of the dissection or its antegrade or retrograde progression. In 12 type A and 11 type B dissections the aorta was repaired using an intraluminal prosthesis to reduce the risk of hemorrhage and its related complications. Overall mortality rates were 33% in type A and 36% in type B patients, similar to that observed in patients operated with other techniques, but the incidence of intraoperative bleeding was possibly reduced and the cross-clamping time was significantly shorter. This method of repair is a sound alternative to conventional anastomotic suturing, particularly in clinically compromised patients and in the hands of surgeons on call, who may lack the experience of dealing with a particularly fragile aortic wall.

Aged↗
PubMed1986

Late results after left-sided cardiac valve replacement in children.

Selection of types of cardiac valve substitutes for children remains controversial. Between 1976 and 1984, 166 children, 15 years of age or younger, underwent aortic (N = 53) or mitral valve replacement (N = 90) or both (N = 23). Biological prostheses were used in 84 patients and mechanical prostheses in 71; both a mitral bioprosthesis and an aortic mechanical valve were used in 11 patients. The overall early mortality was 9%. Mean follow-up intervals were 4.1 years for the bioprosthesis group, 3.3 years for the mechanical valve group, and 3.5 years for the group receiving both. The 7 year survival rates (+/- standard error) were 63% +/- 6% in the bioprosthesis group and 70% +/- 7% in the mechanical valve group (p = NS). After aortic valve replacement the 7 year survival rates were 66% +/- 14% (bioprosthesis group) and 77% +/- 9% (mechanical valve group) (p = NS); after mitral valve replacement the rates were 65% +/- 7% (bioprosthesis group) and 54% +/- 17% (mechanical valve group) (p = NS). The incidence of thromboembolic events was 0.6% +/- 0.4% per patient-year in the bioprosthesis group (none after aortic valve replacement, 0.8% +/- 0.6% per patient-year after mitral valve replacement) and 1.4% +/- 0.8% per patient-year in the mechanical valve group (0.7% +/- 0.7% per patient-year after aortic valve replacement, 4.0% +/- 2.8% per patient-year after mitral valve replacement) (p = NS). The linearized rates of reoperation were 10.4% +/- 1.8% per patient-year (bioprosthesis group) and 2.3% +/- 1.0% per patient-year (mechanical valve group) (p less than 0.001). The 7 year probability rates of freedom from all valve-related complications were 43% +/- 6% in the bioprosthesis group and 86% +/- 4% in the mechanical valve group (p less than 0.001). In the aortic position, a mechanical adult-sized prosthesis can always be implanted, and satisfactory long-term results can be anticipated. In the systemic atrioventricular position, the results are less than satisfactory with either type of prosthesis; every effort should be made to preserve the natural valve of the child.

Adolescent↗
PubMed1985

Prevention of prosthetic disc immobilization by prolapsed sutures.

Disc immobilization by prolapsed sutures is a rare but potential risk after prosthetic heart valve replacement. We present here a simple technical modification used during prosthetic valve insertion, which can prevent the occurrence of such a complication.

Aortic Valve↗
PubMed1985

Results of reoperation for primary tissue failure of porcine bioprostheses.

Results of reoperation for primary tissue failure of porcine bioprostheses were evaluated in 574 patients discharged from the hospital from 1970 to 1981. A total of 413 had undergone isolated mitral valve replacement and 161 isolated aortic valve replacement. Through March, 1984, 88 patients (15%) had required reoperation: 59 had undergone mitral and 29, aortic valve replacement. Primary tissue failure was the main cause of bioprosthetic dysfunction; it occurred in 64 patients (46 mitral and 18 aortic) at a mean postoperative interval of 93 +/- 4 months (range 34 to 158). During the same period, 11 patients required reoperation for bioprosthetic endocarditis, 11 for paravalvular leak, and two for thrombosis. These patients are not included in this review. Reoperation for primary tissue failure was performed after a mean interval of 72 +/- 6 months (range 38 to 158) for patients with aortic bioprostheses and after 101 +/- 5 months (range 34 to 153) for those with mitral bioprostheses (p less than 0.05). Overall mortality at reoperation was 12.5%: 11% for the mitral group and 16% for the aortic group. In 62 patients (45 mitral and 17 aortic) primary tissue failure was caused by calcification of the cusps, associated with severe fibrous tissue overgrowth in seven. Bioprosthetic failure was caused by an intracuspal hematoma in one patient with mitral valve replacement and by lipid infiltration of the cusps in one patient with aortic valve replacement. Actuarial freedom from bioprosthetic primary tissue failure at 12 years is 61% +/- 5% for the mitral group and 69% +/- 7% for the aortic group. On the basis of our long-term follow-up of patients after mitral or aortic replacement with a porcine bioprosthesis, we conclude: primary tissue failure is the most frequent indication for reoperation in patients with a porcine bioprosthesis; calcification of the cusp tissue is the leading cause of primary tissue failure; reoperation for primary tissue failure may be a major concern, although mortality for elective cases is low; and the limited durability of porcine bioprostheses suggests their use be restricted to selected patients.

Animals↗
PubMed1984

Calcific degeneration as the main cause of porcine bioprosthetic valve failure.

Sixty-seven glutaraldehyde-processed porcine bioprostheses (PBs), recovered at autopsy or reoperation from 65 patients, were evaluated by roentgenologic and pathologic examination. Seven patients with 8 PBs were younger than 20 years of age. The time interval of function was 2 to 138 months (average 62). Pathologically, 53 explants had signs of intrinsic dysfunction, which was ascribed to calcification in 36 (68%). By x-ray examination, calcific deposits were found in 55 of 67 PBs (82%). The mean duration of function was 70 +/- 32 months in calcified PBs vs 27 +/- 18 months in noncalcified PBs (p less than 0.001). All 26 PBs that had been in place for longer than 6 years were calcified. In 45 PBs the Ca++ deposits were considered severe (mean time of function 76 +/- 32 months) and mild in 10 (mean time of function 44 +/- 22 months) (p less than 0.005). The Ca++ deposits were located at the commissures in 54 PBs (98%), at the body of cusps in 41 (75%), at the free margin in 37 (67%) and at the aortic wall in 37 (67%). When mild, Ca++ deposits involved the commissures in 90% of cases, the body of cusps in 30% and the free margin only in 10%. Forty-seven calcified PBs were mounted on a flexible stent, and 8 had a rigid stent, with an average time of function of 63 +/- 28 and 113 +/- 18 months, respectively (p less than 0.00001). Ca++ dysfunction occurred earlier in the aortic than in the mitral position (59 +/- 19 vs 86 +/- 35 months, p less than 0.05). All the PBs explanted from young patients and 47 of 59 PBs removed from adult patients were calcified, with an average time of function of 50 +/- 21 vs 73 +/- 33 months, respectively (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗