Paolo Stassano

Aortic Valve Replacement: A Prospective Randomized Evaluation of Mechanical Versus Biological Valves in Patients Ages 55 to 70 Years

OBJECTIVES The aim of this study was to determine long-term results between bioprosthetic (BP) and mechanical (MP) aortic valves in middle-aged patients. BACKGROUND It has not been established which is the best aortic valve substitute in patients ages 55 to 70 years. We conducted a randomized study to compare long-term outcomes between BP and MP aortic valves. METHODS Between January 1995 and June 2003, 310 patients were randomized to receive a BP or an MP aortic valve. Primary end points of the study were survival, valve failure, and reoperation. RESULTS One hundred fifty-five patients received a BP valve, and 155 patients received an MP valve. Four patients died, perioperatively, in the MP group (2.6%), and 6 patients died in the BP group (3.9%, p = 0.4). At late follow-up (mean 106 +/- 28 months) 41 patients died in the MP group and 45 patients died in the BP group (p = 0.6). There was no difference in the survival rate at 13 years between the MP and BP groups. Valve failures and reoperations were more frequent in the BP group compared with the MP group (p = 0.0001 and p = 0.0003, respectively). There were no differences in the linearized rate of thromboembolism, bleeding, endocarditis, and major adverse prosthesis-related events (MAPE) between the MP and BP valve groups. CONCLUSIONS At 13 years, patients undergoing aortic valve replacement either with MP or BP valves had a similar survival rate as well the same rate of occurrence of thromboembolism, bleeding, endocarditis, and MAPE, but patients who had undergone aortic valve replacement with BP valves faced a significantly higher risk of valve failure and reoperation.

Intracardiac migration of nitinol TrapEase vena cava filter and paradoxical embolism

The nitinol TrapEase inferior vena cava filter is a new device for pulmonary embolism prophylaxis. No cases of filter migration or filter-related complications with this type of device have so far been described. We report a case of intracardiac migration of this filter in a patient with a patent foramen ovale, resulting in severe cardiogenic shock, cerebral and right arm paradoxical embolism. Surgical treatment, results, causes of these complications are discussed.

Combination therapy with warfarin plus clopidogrel improves outcomes in femoropopliteal bypass surgery patients

BACKGROUND Patients having undergone femoropopliteal bypass surgery remain at significant risk of graft failure. Although antithrombotic therapy is of paramount importance in these patients, the effect of oral anticoagulation therapy (OAT) on outcomes remains unresolved. We performed a randomized, prospective study to assess the impact of OAT plus clopidogrel vs dual antiplatelet therapy on peripheral vascular and systemic cardiovascular outcomes in patients who had undergone femoropopliteal bypass surgery. METHODS Three hundred forty-one patients who had undergone femoropopliteal surgery were enrolled and randomized: 173 patients received clopidogrel 75 mg/d plus OAT with warfarin (C + OAT), and 168 patients received dual antiplatelet therapy with clopidogrel 75 mg/d plus aspirin 100 mg/d (C + acetylsalicylic acid [ASA]). Study end points were graft patency and the occurrence of severe peripheral arterial ischemia, and the incidence of bleeding episodes. RESULTS Follow-up ranged from 4 to 9 years. The graft patency rate and the freedom from severe peripheral arterial ischemia was significantly higher in C + OAT group than in C + ASA group (P = .026 and .044, respectively, Cox-Mantel test). The linearized incidence of minor bleeding complications was significantly higher in C + OAT group than in C + ASA group (2.85% patient-years vs 1.37% patient-years; P = .03). The incidence of major adverse cardiovascular events, including mortality, was found to be similar (P = .34) for both study groups. CONCLUSIONS In patients who have undergone femoropopliteal vascular surgery, combination therapy with clopidogrel plus warfarin is more effective than dual antiplatelet therapy in increasing graft patency and in reducing severe peripheral ischemia. These improvements are obtained at the expenses of an increase in the rate of minor anticoagulation-related complications.

Randomized flow capacity comparison of skeletonized and pedicled left internal mammary artery.

BACKGROUND The preferential harvesting technique of the internal mammary artery has been periodically debated. This randomized study evaluated the flow outcome of the skeletonized versus pedicled left internal mammary artery. METHODS Two hundred patients undergoing surgery for left anterior descending coronary artery revascularization were enrolled and randomized to pedicled (n=100) or skeletonized (n=100) harvesting. Intraoperative baseline flow and post adenosine infusion into the left ventricle, hospital outcome, echocardiographic results, and troponin I leakage were analyzed. Noninvasive periodic evaluation of flow was carried out at rest and during intravenous adenosine infusion by transthoracic Doppler ultrasound, and was stratified according to the harvesting technique. Final angiographic evaluation was performed by 64-slice multidetector computed tomography. RESULTS Skeletonized left internal mammary arteries demonstrated better flow capacity at rest and during adenosine recruitment perioperatively and at all time points of follow-up. Troponin I leakage was significantly higher in the pedicled group (59 vs 42, p=0.02). Pedicled harvesting (hazard ratio [HR] 3.6, 95% confidence interval [CI] 2.5 to 6.9, p<0.001); indexed left ventricular mass greater than 150 g/m2 (HR 4.6, 95% CI 3.1 to 7.5, p<0.001); and baseline corrected thrombolysis in myocardial infarction frame count greater than 30 (HR 4.4, 95% CI, 3.8 to 7.2, p<0.001) were the most powerful multivariable predictors of graft flow reserve less than 2.0. Postoperative echocardiographic results and clinical and angiographic outcomes were comparable between the two groups. CONCLUSIONS Skeletonization of the left internal mammary artery, beyond traditional proven advantages, provided significantly higher flow capacity and better graft flow reserve.

Preoperative Intraaortic Balloon Pump for Off-Pump Coronary Arterial Revascularization

BACKGROUND Prophylactic intraaortic balloon pump (IABP) support showed better outcomes in critical patients undergoing coronary revascularization compared with intraoperative or postoperative insertion. We conducted a prospective, randomized study to determine the optimal timing for preoperative IABP insertion in high-risk patients undergoing off-pump coronary artery revascularization. METHODS The study enrolled 230 consecutive high-risk patients (having a logistic European System for Cardiac Operative Risk Evaluation score of ≥10) undergoing off-pump coronary artery revascularization. They were randomized for preoperative IABP starting at 2 hours (2T, n=115) or 12 hours (12T, n=115). Clinical, biochemical, and hemodynamic results, and the need for inotropic drug support, were markers of outcome and compared between groups. RESULTS Hospital mortality in group 12T was reduced by 60%, but the difference between groups was not statistically significant (hazard ratio, 0.4; 95% confidence interval, 0.1 to 1.5; p=0.1). Twelve hours of preoperative IABP therapy reduced postoperative low output syndrome (hazard ratio, 0.4; 95% confidence interval, 0.1 to 0.9; p=0.03) and biomarker leakage upper normal limit (hazard ratio, 0.3; 95% confidence interval, 0.1 to 0.7; p=0.001). Postoperative left ventricular function was similar between the groups. Group 2T patients required higher inotropic support for a longer average duration and prolonged postoperative intensive care unit and hospital length of stay. CONCLUSIONS Twelve hours preoperative IABP therapy improved treatment efficacy. Postoperative morbidity was reduced, but hospital mortality rate was not affected. The IABP-related complication rate was low and not related to the length of treatment.

Serial Evaluation of Flow in Single or Arterial Y-Grafts to the Left Coronary Artery

BACKGROUND It is unclear whether composite Y-grafts can withstand the flow demand of the coronary system at rest and under stress. This study compared the graft flow and flow reserve of the left internal mammary artery (LIMA) intraoperatively and over a 2-year follow-up in single or composite Y-graft configurations using the radial artery (RA). METHODS One hundred patients who underwent off-pump myocardial revascularization with a composite Y-graft (group 2) were compared with a homogeneous group of 100 patients treated with a single independent LIMA graft on the left anterior descending artery (LAD) (group 1). Intraoperative baseline flow and flow after adenosine infusion into the left ventricle were analyzed. Over a 2-year follow-up, noninvasive longitudinal evaluation of flow was carried out at rest and during maximal hyperemic response by transthoracic Doppler ultrasonography. Final functional evaluation was obtained through a 2-day stress/rest 99mTc-sestamibi myocardial perfusion single-photon emission computed tomographic scan. RESULTS The proximal LIMA in a Y-graft configuration showed adaptability to flow dynamics. It had a greater average peak velocity (p = 0.02), flow volume (p < 0.01), and diameter (p < 0.01) than independent single LIMA grafts. Distal flow at rest and during adenosine recruitment was similar between groups both intraoperatively and at all time points of the follow-up. No steal phenomenon occurred at rest, nor was it induced by adenosine in the Y-graft group. Exercise nuclear scintigraphy showed satisfactory exercise tolerance and no inducible significant perfusion defects in both groups. CONCLUSIONS Left internal mammary artery Y-grafting with the RA is adequate for flow requirements of distal branches at rest and during maximal hyperemia and is able to adapt its dimension to flow demand. Optimal results for RA anastomoses are possible only in arteries with critical stenosis and of good size and quality.

Massive air embolism during cardiopulmonary bypass: successful treatment with immediate hypothermia and circulatory support.

Two patients experienced an episode of massive air embolism during extracorporeal circulation. Several emergency measures were taken. (1) The roller pump was reversed to take out air from the aorta. (2) The circuit was disconnected and recirculated to eliminate air bubbles. (3) Perfusion was restarted and the patient cooled to 24 degrees C for 40 minutes. (4) Pentothal (thiopental), steroids, and assisted ventilation were administered. The outcome was favorable in both patients, and there were no neurological sequelae. Immediate cooling and prolonged circulation seem to be a satisfactory approach to this problem.

Endothelial Nitric Oxide Synthase Expression in Postmenopausal Women: A Sex-Specific Risk Factor in Coronary Surgery

BACKGROUND After coronary artery bypass graft surgery, older women have less favorable clinical outcome and lower conduit patency compared with men. This less favorable outcome can be in part ascribed to impaired endothelium-derived nitric oxide (eNOS) production. This study evaluated endothelial nitric oxide synthase expression in internal mammary artery from postmenopausal women undergoing coronary artery bypass graft surgery. METHODS Internal mammary artery segments were obtained from 20 postmenopausal woman and 20 matched male patients. Twenty more segments from younger patients were used as controls. Expression of eNOS messenger RNA in internal mammary artery endothelial cells were evaluated by polymerase chain reaction and real-time quantitative reverse transcription polymerase chain reaction. The eNOS protein level was assayed by Western blot. Vascular dynamics of specimens were evaluated by organ chamber methodology. RESULTS In postmenopausal women, the band of messenger RNA for eNOS was reduced by 37.4% and by 25.2%, respectively, compared with matched men and the control group (62.6%±4.8% versus 74.8%±5.3%, p<0.001). In comparison with the control group lane, the eNOS protein immunoreactive band was 44.2% decreased in postmenopausal women and 34.5% decreased in matched men, and was significantly decreased in postmenopausal women as compared with matched men (55.8%±4.6% versus 65.5%±5.2%, p<0.001). Nitric oxide-mediated vasomotor dynamics were consistent with reduced eNOS production. CONCLUSIONS Internal mammary artery endothelial cells from women after menopause undergoing coronary surgery have impaired expression of messenger RNA for eNOS and reduced eNOS levels. Reduced bioactivity of nitric oxide translates into impaired endothelial metabolism that could contribute to worse surgical outcome.

Myocardial metabolism and diastolic function after aortic valve replacement for aortic stenosis: influence of patient–prosthesis mismatch

OBJECTIVE This study evaluated the impact of patient-prosthesis mismatch on myocardial function and high-energy phosphate metabolism after aortic valve replacement for pure aortic stenosis. Patients with and without patient-prosthesis mismatch were compared using magnetic resonance techniques. METHODS Thirty patients who had undergone aortic valve replacement with Medtronic Mosaic bioprosthesis were evaluated. Fifteen patients with patient-prosthesis mismatch were compared to 15 matched patients without patient-prosthesis mismatch. These two homogeneous groups were studied for myocardial metabolism and left ventricle function preoperatively and at 12 months postoperatively with magnetic resonance imaging and (31)P spectroscopy. RESULTS All patients experienced improvement in myocardial metabolism and left ventricle function. Left ventricle mass regression was impaired in both groups. Impaired diastolic filling was associated with increased left ventricle wall mass in both groups (patient-prosthesis mismatch: R(2) = -0.71, p = 0.002; no patient-prosthesis mismatch: R(2) = -0.88, p < 0.001). Myocardial phosphocreatine/adenosine triphosphate ratio revealed a modest correlation with left ventricle function as evaluated by early acceleration peak (patient-prosthesis mismatch: R(2) = 0.37, p = 0.03; no patient-prosthesis mismatch: R(2) = 0.17, p = 0.02) and early deceleration peak (patient-prosthesis mismatch: R(2) = 0.30, p = 0.01; no patient-prosthesis mismatch: R(2) = 0.39, p = 0.008). No significant correlation between the phosphocreatine/adenosine triphosphate ratio and left ventricle mass was found (patient-prosthesis mismatch: R(2) = 0.39, p = 0.6; no patient-prosthesis mismatch: R(2) = 0.40, p = 0.08). CONCLUSION Aortic valve replacement leads to early improvement of left ventricle function and myocardial metabolism in all patients regardless of the occurrence of patient-prosthesis mismatch.

Bioprosthetic replacement after bioprosthesis failure: a hazardous choice?

BACKGROUND Following bioprosthetic failure, replacement is usually done with mechanical valves to avoid repeated reoperations. METHODS From 1986 to 1996 we operated on 130 patients with bioprosthetic failure, implanting a new bioprosthesis; this group included patients with contraindication to anticoagulation, tricuspid replacement, and specific patient requests. Mean age was 63+/-8 years. RESULTS The perioperative mortality was 13.8%. At 10 year follow-up the actuarial estimate of survival was 77.4%+/-6.6%. Freedom from structural valve deterioration was estimated at 81.8%+/-6.3%. Freedom from a third operation was estimated at 85.5%+/-5.2%. No patient was permanently anticoagulated. Freedom from thromboembolism was estimated at 91.5%+/-4%, and there were no hemorrhages. Freedom from cardiac-related deaths was estimated at 85.7%+/-5%. CONCLUSIONS This group of patients received the first valve between 1976 and 1986; the range of the cumulative follow-up reaches 20 years, and the extended survival compares favorably with survival of mechanical valves.