Myocardial infarction scar plication in the rat: Cardiac mechanics in an animal model for surgical procedures

Background. the immediate effects of surgical reduction of left ventricle cavity on cardiac mechanics have not been well defined.Methods. Cardiac mechanics were analyzed before and after myocardial infarction scar plication in 11 isolated infarcted rat hearts.Results. Despite a decrease in myocardial stiffness, an increase in chamber stiffness was noted after myocardial infarction scar plication. Systolic function was favored in more than one way. for the same diastolic pressures, maximal developed pressures were higher after myocardial infarction scar plication, and the slope of the systolic pressure-volume relationship was steeper afterwards as compared with before; this means that Frank-Starling recruitment is accentuated in smaller cavities. in addition, the developed net forces needed to generate these pressures were clearly lower afterward than before, indicating reduced ventricular afterload.Conclusions. the study results show that diastolic function is harmed and systolic function is favored by myocardial infarction scar plication. We suggest that preoperative evaluation of the degree of diastolic dysfunction and impairment of the Frank-Starling mechanism may help to identify patients who may have a poor postoperative outcome due to diastolic or systolic dysfunction.Universidade Federal de São Paulo, Dept Physiol, BR-04022000 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Surg, BR-04022000 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Internal Med, BR-04022000 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Physiol, BR-04022000 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Surg, BR-04022000 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Internal Med, BR-04022000 São Paulo, BrazilWeb of Scienc

Off-pump versus on-pump myocardial revascularization in low-risk patients with one or two vessel disease: Perioperative results in a multicenter randomized controlled trial

Background. To evaluate hospital mortality and morbidity after myocardial revascularization in a prospective and multicenter study, comparing on-pump versus off-pump in a special subset of patients with lesions in the left descending artery, alone or associated with the right coronary artery.Methods. A multicenter prospective randomized study was performed. One hundred and sixty selected low-risk patients were enrolled; 80 patients were operated on-pump (coronary artery bypass grafting [CABG], group I) and 80 patients were operated off-pump (off-pump coronary artery bypass [OPCAB], group II). One hundred and five were male and ages ranged from 39 to 70 years old; mean 58.81 +/- 9.31 and median 59. Preoperative clinical characteristics were similar in both groups; only previous myocardial infarction was higher in the OPCAB group. Patients with severe left ventricular dysfunction (FE less than or equal to 35%), renal failure and lesions of the circumflex artery and its branches were excluded, as well as patients with significant comorbidities that were inappropriate for randomization because we selected them for OPCAB procedures.Results. Hospital mortality was 2.5%, three patients (3.7%) in group I (on-pump) and one patient (1.2%) in group II (off-pump) (ns). the number of grafts per patients in group I was 1.81 +/- 0.6, and 1.77 +/- 0.68 in group II (p = 0.833). There was no difference in the total operation time 205.10 +/- 54.30 minutes in group I and 189.50 +/- 55.44 in group II (ns). Six patients (7.5%) had myocardial infarction in group I and three (3.7%) in group II (ns). Bleeding in the postoperative period was 680.50 +/- 434.1 mL, in the on-pump group and 678.6 +/- 357.0 mL in the off-pump group (ns). Three patients (3.7%) presented transient neurologic dysfunction in group I and six patients (7.5%) in group II (ns). Intensive care stay was 2.4 +/- 1.0 days in the CABG and 2.3 +/- 0.98 days in the OPCAB group (ns).Conclusions. We did not find any statistical difference in hospital mortality and morbidity using on-pump or off-pump techniques for low-risk patients. (C) 2004 by the Society of Thoracic Surgeons.Universidade Federal de São Paulo, Dept Surg, Div Cardiovasc Surg, São Paulo, BrazilReal & Benemerita Soc Beneficencia Portuguesa Sao, São Paulo, Go, BrazilUniversidade Federal de São Paulo, Dept Surg, Div Cardiovasc Surg, São Paulo, BrazilWeb of Scienc

Is the number of microembolic signals related to neurologic outcome in coronary bypass surgery?

Coronary artery bypass surgery (CABG) without cardiopulmonary bypass (CPB) may potentially reduce the number of microembolic signals (MES) associated with aortic manipulation or generated by the pump circuit, resulting in a better neurologic outcome after surgery. Our aim was to compare the frequency of MES and neurologic complications in CABG with and without CPB. Twenty patients eligible to routine CABG without CPB were randomized to surgery with CPB and without CPB and continuously monitored by transcranial Doppler. Neurologic examination was performed in all patients before and after surgery. The two groups were similar with respect to demographics, risk factors, grade of aortic atheromatous disease and number of grafts. The frequency of MES in the nonCPB group was considerably lower than in CPB patients, however, we did not observe any change in the neurologic examination during the early postoperative period. Neurologic complications after CABG may be related to the size and composition of MES rather than to their absolute numbers. A large prospective multicentric randomized trial may help to elucidate this complex issue

A juvenile sheep model for the long-term evaluation of stentless bioprostheses implanted as aortic root replacements

Background and aim of the study: Orthotopic valve replacement in large animals is an important component of the preclinical assessment of bioprosthetic valves. To provide the most useful preclinical information, the development of models that parallel clinical practice patterns is essential. Therefore, we sought to develop a technically feasible and reproducible model for chronic evaluation of stentless bioprosthetic aortic valves implanted as aortic root replacements in juvenile sheep.Methods: Juvenile domestic sheep (mean age 21 2.28 weeks; range: 17-26 weeks) underwent aortic root replacement using standard cardiopulmonary bypass (CPB) and surgical techniques. Animals were implanted with 19 mm (n = 21), 21 mm (n = 18) or 23 mm (n = 4) bioprostheses from two different manufacturers, and followed for 150 days. Animals surviving at least 150 days were considered long-term survivors; those which died prior to postoperative day (POD) 31 were considered operative deaths.Results: Forty-three animals underwent aortic root replacement. The mean CPB time was 91 +/- 20 min (range: 62-149 min); mean cross-clamp time was 63 +/- 13 min (range: 39-95 min). Thirty-five animals (81%) survived the first 30 days of the study period. Five deaths occurred at POD 0 due to anastomotic complications. One death occurred each on POD 3, 6, and 26 as a result of prosthesis size mismatching, thromboembolic complications, and endocarditis, respectively. There were five late deaths. Twenty animals survived the minimum 150-day study period, and 12 were sacrificed at 183 +/- 17 days. Six animals remain alive at 151 +/- 0.98 days, and one animal died each on POD 184 and 190. The remaining 10 animals are not yet 150 days from their operation. Currently, all are well at 102 +/- 34 days (range: 33-140) days.Conclusion: These data suggest that long-term evaluation of stentless aortic bioprostheses implanted as aortic root replacements can be accomplished using juvenile sheep.Univ Minnesota, Dept Surg, Div Expt Surg, Minneapolis, MN 55455 USAUniv Minnesota, Div Thorac & Cardiovasc Surg, Minneapolis, MN 55455 USAEscola Paulista Med, Dept Cardiovasc & Thorac Surg, BR-04023 Sao Paulo, BrazilLabcor Labs Ltda, Belo Horizonte, MG, BrazilEscola Paulista Med, Dept Cardiovasc & Thorac Surg, BR-04023 Sao Paulo, BrazilWeb of Scienc