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Biomedical subjects

A Milano

Publications and source records attributed to A Milano.

At least 73 records · Page 4Linked to original sources
PubMed1994

Sequence of the gene encoding an alkaline serine protease of thermophilic Bacillus smithii.

The complete nucleotide sequence of the gene encoding an alkaline serine protease from Bacillus smithii has been determined. Degenerate oligodeoxyribonucleotide primers were used to prime the amplification of a 507-bp sequence of the gene. This sequence was successively used for constructing new primers applied in inverse polymerase chain reaction, using as template self-ligated DNA fragments. The deduced amino-acid sequence is compared to serine proteases from B. amyloliquefaciens, B. licheniformis, B. subtilis and Thermus aquaticus.

Amino Acid Sequence↗
PubMed1994

Hancock II porcine bioprosthesis: excellent durability at intermediate-term follow-up.

OBJECTIVES: This study aimed to assess the clinical performance and durability of a new generation of porcine valve, the Hancock II bioprosthesis, at intermediate-term follow-up. BACKGROUND: Standard porcine bioprostheses undergo progressive structural deterioration, mainly due to cusp and commissural calcification, affecting durability and requiring reoperation. The Hancock II bioprosthesis, which is currently undergoing clinical investigation, is made from a porcine aortic valve treated with a calcium-retarding agent (sodium dodecyl sulfate [T6]), which should delay onset of calcification and increase durability. METHODS: From May 1983 to December 1992, we used the Hancock II bioprothesis in aortic (59 patients), mitral (101 patients) and mitral-aortic (25 patients), valve replacement procedures. Postoperative follow-up ranged from 0.1 to 8.7 years (mean [+/- SD] 4.5 +/- 2.6 years) and was 100% complete. Freedom from major postoperative events was calculated at 7 years for patients with aortic valve replacement and at 8 years for those with mitral and mitral-aortic valve replacement. RESULTS: The actuarial survival rate was 48 +/- 10%, 76 +/- 3% and 63 +/- 6%; freedom from valve-related mortality was 91 +/- 4%, 94 +/- 2% and 89 +/- 6%; freedom from thromboembolism was 80 +/- 11%, 90 +/- 2% and 79 +/- 7%; and freedom from reoperation was 100%, 97 +/- 1% and 89 +/- 6% after aortic, mitral and mitral-aortic valve replacement, respectively. No structural valve deterioration occurred. CONCLUSIONS: At intermediate-term follow-up the Hancock II bioprosthesis showed excellent durability in all positions. However, the effectiveness of anticalcification treatment must be assessed with longer follow-up studies.

Actuarial Analysis↗
PubMed1994

Mid-term results of heart transplantation in diabetic patients.

BACKGROUND: Diabetes mellitus (DM) has been considered a relative contraindication to heart transplantation (HTx) because of possible increased infection rates and worsening DM with prednisone immunosuppression. The introduction of cyclosporine has allowed us to reduce the dosage of oral steroids and to accept DM patients (pts) for HTx. We reviewed the mid-term outcome of our DM pts who had undergone HTx. MATERIALS AND METHODS: Out of 257 HTx recipients, 19 males and 3 females, aged 53 +/- 8 years, were diabetic. Prior to HTx, DM was controlled with insulin in 5, with oral hypoglycemic agents in 7 and with diet in the remaining patients. Immunosuppression consisted of cyclosporine and azathioprine; low-dose prednisone was added in 10 patients because of repeated rejections. RESULTS: All patients survived HTx and were followed 2 to 75 (mean 38 +/- 21) months. There were 4 late deaths, with actuarial survival of 84% at 5 years. DM was more difficult to control after HTx (12 patients requiring insulin vs 5 pre-HTx), but comparison of diabetic vs non diabetic patients following HTx showed no significant difference in frequency of rejection or infection during the 1st year (2.6 +/- 1.6 vs 2.1 +/- 1.5; 0.5 +/- 0.4 vs 0.4 +/- 0.3 episode/patient respectively) and in 5-year actuarial survival (84% vs 77%). Renal function is preserved in all DM patients, hypertension has developed in 11/18 (61%); annual post-HTx cardiac catheterisation has shown normal graft function and coronary arteries in all but 2 patients. CONCLUSIONS: Mid-term results indicate that HTx can be safely performed in diabetic patients; a longer follow-up is required to determine whether DM is no longer a contraindication to HTx.

Actuarial Analysis↗
PubMed1994

Results of heart transplantation by extending recipient selection criteria.

From November 1985 to July 1993, 29 out of 241 patients (12%) who underwent heart transplantation (HTx) at our institution had one or more "classical" contraindications to HTx: age > or = 60 years (20 patients); insulin-dependent diabetes mellitus (5 patients); irreversible renal failure requiring combined heart-kidney transplantation (2 patients); previous surgery for malignancy (1 patient); familial hypercholesterolemia (1 patient) and active systemic infection (1 patient). The main indication for HTx was ischemic cardiomyopathy (21 patients, 61%). Immunosuppression regimen consisted of Cyclosporine and Azathioprine, oral prednisone being subsequently added in 6 patients because of persistent rejection. There were 2 perioperative deaths and one late death. Follow-up ranged from 1 to 88 months (mean, 28 +/- 20) with an actuarial survival at 5 years of 85 +/- 8%. Annual cardiac catheterization demonstrated normal graft function and coronary arteries in all. No significant differences in survival, incidence of rejection and infection, renal function and duration of hospitalization were found when these patients were compared with those with no contraindications to HTx. In conclusion, HTx can be performed with good early clinical results in selected patients with "classical" contraindications to HTx; longer follow-up, however, is needed to confirm whether extension of the recipient selection criteria justified.

Adult↗
PubMed1994

Early and late outcome after reoperation for prosthetic valve dysfunction: analysis of 549 patients during a 26-year period.

Factors influencing operative mortality and late survival of 549 patients undergoing a first reoperation for prosthetic valve failure during the interval from 1966 to 1992 were analyzed; 347 patients had reoperation on a mitral prosthesis, 173 on an aortic prosthesis and 29 on both aortic and mitral prostheses. Univariate analysis showed that hospital mortality was higher in patients in functional class IV compared with those in class II-III (35% vs. 8%, p < 0.001), in those who required emergency reoperation (57% vs. 11%, p < 0.001), in those reoperated for endocarditis (59%) or valve thrombosis (43%) compared with those reoperated for structural valve deterioration (9%, p < 0.001), and in those with a failing mechanical prosthesis compared to patients with a bioprosthesis (21% vs. 10%, p < 0.05). Furthermore, operative mortality decreased from 41% in the period from 1966 to 1977, to 12% from 1977 to 1983 and to 8% from 1984 to 1992 (p < 0.001). Hospital survivors were followed from 0.1 to 22 years (mean follow-up 11 +/- 5 years) with an overall actuarial survival at 15 years of 24 +/- 5%. At 15 years actuarial survival is 24 +/- 5% for patients in preoperative functional class II-III and 20 +/- 6% for those in functional class IV (p < 0.05). It is concluded that in prosthetic valve recipients both early and late outcome is greatly influenced by preoperative clinical status. Increasing surgical experience, better myocardial protection and patient management have contributed to reducing the operative risk. More accurate patient follow up and possibly earlier reoperation might also improve the long term outcome.

Adolescent↗
PubMed1994

The Cabrol technique for replacement of the aortic valve and totally calcified ascending aorta: a case report.

Simultaneous replacement of the ascending aorta and aortic valve with a valved conduit was performed in a patient with aortic valve disease and totally calcified ascending aorta. Coronary circulation could be re-established by using the Cabrol technique, but only after extensive decalcification of the aortic wall surrounding the coronary ostia. This technique appears particularly suitable in patients who require combined replacement of the ascending aorta and aortic valve in the presence of diffuse calcification of the aortic root.

Aged↗
PubMed1994

Donor shortage in heart transplantation. Is extension of donor age limits justified?

Chronic shortage of donor organs for heart transplantation led us to extend donor age limits. To verify the effectiveness of such a policy we have compared the results of heart transplantation in 45 patients with donors more than 40 years of age (group 1) with those of 72 patients older than 50 years of age who had heart transplantation with younger donors (group 2) between November 1985 and December 1992. The two groups were comparable in terms of mean recipient age, recipient and donor sex, and indication for heart transplantation. Mean donor age was 46 +/- 4 years (range 41 to 59 years) in group 1 and 23 +/- 7 years (range 8 to 39 years) in group 2 (p < 0.001). In group 1 cerebrovascular accidents were more common as the cause of donor death (60% versus 16%, p = 0.001), and no difference was found in ischemic time (144 +/- 47 minutes versus 140 +/- 48 minutes, p = not significant). There were 6 early (< 30 days) deaths in group 1 (13%) and 10 in group 2 (14%; p = not significant). Fatal acute graft failure was more prevalent, but not significantly so, in group 1 (10% versus 5.5%, p = not significant). Mean follow-up was 29 +/- 20 months (range 3 to 78 months) in group 1 and 30 +/- 20 months (range 3 to 80 months) in group 2 (p = not significant). At 5 years actuarial survival was 80% +/- 6% in both groups with comparable graft performance at echocardiographic and hemodynamic control studies. A significant difference was found in freedom from any type of coronary artery abnormality between group 1 (49% +/- 13%) and group 2 (77% +/- 8%) at 5 years (p < 0.05); however, freedom from coronary stenotic lesions only was similar. Major conduction disturbances have occurred more frequently in patients of group 1 (37% versus 12%; p = 0.003) without any difference in the need for permanent pacing. Donors older than 40 years of age can be accepted for heart transplantation with early and long-term results comparable with those obtained with younger donors. The impact of a higher incidence of coronary abnormalities on late performance of older grafts must be assessed at longer follow-up. Our results indicate that, because of the current organ shortage, extension of donor age limits is justified, even up to the sixth decade of life in selected cases.

Actuarial Analysis↗
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

Long term survival without anticoagulation after aortic valve replacement with a Lillehei-Kaster prosthesis. A case report.

A patient who underwent aortic valve replacement with a Lillehei-Kaster prosthesis developed an early duodenal ulcer requiring suspension of warfarin treatment. Subsequently he was managed without oral anticoagulants, receiving only antiplatelet agents, starting from the third postoperative year. Neither thromboembolic nor hemorrhagic complications occurred but at reoperation, performed almost 20 years later for prosthetic stenosis caused by a fibrous ring, and aneurysm of the ascending aorta, mild fresh thrombus was found on the prosthetic ring. Although the long term outcome of patients with a mechanical aortic prosthesis can occasionally be successful even without long term anticoagulation, such management appears to be justified only in highly selected cases.

Anticoagulants↗
PubMed1993

Tricuspid valve endocarditis: repair with the use of artificial chordae.

We report on a patient who developed tricuspid valve endocarditis on a permanent endocardial pacemaker lead. At operation the endocardial lead was removed and accurate debridement of the tricuspid tissue was performed. Tricuspid valve reconstruction included commissural plication and the construction of artificial polytetrafluoroethylene chordae from the anterior leaflet to the anterior papillary muscle to obtain valve competence.

Aged↗
PubMed1993

[Pseudoaneurysm of the left ventricle: a report of 2 cases].

Two cases of left ventricular pseudoaneurysm following myocardial infarction are presented. In the first patient a two-dimensional echocardiography study revealed a small posterior echo-free space that appeared to communicate with the left ventricle through a small defect in the left ventricular posterior wall. Conventional Doppler echocardiography and colour flow imaging demonstrated flow between the left ventricle and the paraventricular chamber. In the other patient, the same study detected an enormous false aneurysm. We found a large extramyocardial echo-free space within the pericardial cavity. The site of this space was posterolateral and communicating with the left ventricular cavity. Cardiac catheterization and surgery confirmed the diagnosis. A postoperative echocardiographic study demonstrated a persistent but smaller saccular echo-free space and a residual shunt through one site of repair in the first patient; in the other, after surgical treatment there was no residual flow, but a left ventricular dysfunction was detected. Two dimensional and color Doppler echocardiography is the best technique among the noninvasive methods, for detecting and following up left ventricular pseudoaneurysms.

Adult↗
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↗