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Biomedical subjects

C A Marrin

Publications and source records attributed to C A Marrin.

25 records · Page 2Linked to original sources
PubMed1992

Should patients with Björk-Shiley valves undergo prophylactic replacement?

About 85,000 patients have undergone replacement of diseased heart valves with prosthetic Björk-Shiley convexo-concave (CC) valves. These valves are prone to fracture of the outlet strut, which leads to acute valve failure that is usually fatal. Should patients with these valves undergo prophylactic replacement to avoid fracture? The incidence of strut fracture varies between 0% and 1.5% per year, depending on valve opening angle (60 degrees or 70 degrees), diameter (less than 29 mm or greater than or equal to 29 mm), and location (aortic or mitral). Other factors include the patient's life expectancy and the expected morbidity and mortality associated with reoperation. We have used decision analysis to identify the patients most likely to benefit from prophylactic reoperation. The incidence of outlet strut fracture was estimated from the data of three large studies on CC valves, and stratified by opening angle, diameter, and location. A Markov decision analysis model was used to estimate life expectancy for patients undergoing prophylactic valve replacement and for those not undergoing reoperation. Prophylactic valve replacement does not benefit patients with CC valves that have low strut fracture risks (60 degrees aortic valves and less than 29 mm, 60 degrees mitral valves). For most patients with CC valves that have high strut fracture risks (greater than or equal to 29 mm, 70 degrees CC), prophylactic valve replacement increases life expectancy. However, elderly patients with such valves benefit from prophylactic reoperation only if the risk of operative mortality is low. Patient age and operative risk are most important in recommendations for patients with CC valves that have intermediate strut fracture risks (less than 29 mm, 70 degrees valves and greater than or equal to 29 mm, 60 degrees mitral valves). For all patients and their doctors facing the difficult decision on whether to replace CC valves, individual estimates of operative mortality risk that take account of both patient-specific and institution-specific factors are essential.

Adult↗
PubMed1991

Transesophageal echocardiography. Preliminary results in patients with traumatic aortic rupture.

Eleven patients with blunt chest trauma at risk for traumatic aortic rupture underwent transesophageal echocardiography to image the descending aorta. Diagnoses were compared with the results of radiographic studies. Ten of the 11 patients underwent arch aortography, with positive results in six cases. In one patient, the results of a computed tomographic scan were interpreted as consistent with aortic rupture. The results of transesophageal echocardiography were positive for ruptured descending aorta in three of six patients with positive aortographic findings, and negative in eight patients. All three patients with positive findings had the diagnosis of ruptured descending aorta confirmed at surgery. The remaining eight patients demonstrated no aortic morbidity. These preliminary findings suggest that transesophageal echocardiography is a useful technique for the diagnosis of ruptured descending aorta following blunt chest trauma.

Adult↗
PubMed1988

Pericardial flap prevents sternal wound complications.

By interposing a pedicle of pericardium between the heart and sternum, mediastinitis may be prevented and sternal healing facilitated. Between Jan 1, 1984, and mid-1986, before we began using the pericardial flap, the overall incidence of mediastinitis and/or sternal wound dehiscence was 2.73% (26 of 952 patients). This rate did not differ significantly among three surgeons (2.53%, 2.95%, and 2.69%). During mid-1986, two of the three surgeons adopted the use of the pericardial flap and used it on 226 of 270 patients. None of these 270 patients developed mediastinitis or sternal wound dehiscence. The third surgeon did not adopt the use of the flap and operated on 100 patients during the same period. In this group, there were three cases of mediastinitis. This difference was statistically significant. No specific complications attributable to construction of a pericardial flap were identified in our patients. We conclude that the routine use of a pericardial flap is a safe, simple, and effective means of preventing mediastinitis and/or sternal dehiscence following cardiac surgery.

Cardiac Surgical Procedures↗
PubMed1988

Atherosclerosis and coronary bypass surgery in hereditary factor VII deficiency.

A 66-year-old man with homozygous deficiency of factor VII (less activity than 4 percent of normal) had a minimal hemorrhagic tendency and severe coronary atherosclerosis, and underwent aortocoronary saphenous vein bypass surgery. Although plasma factor VII coagulant activity and cross-reacting material were markedly reduced, comparable amounts of factor VII antigen were detected in peripheral blood mononuclear cells of both the patient and of a normal subject by Western blotting techniques. Accelerated coagulation was observed following brief exposure of the patient's phytohemagglutinin-stimulated peripheral blood mononuclear cells to low concentrations of ambient factor VII in vitro. Evidence indicates that factor VII plays a role in vivo in both hemostasis and atherogenesis and it might be assumed that factor VII deficiency would both predispose to excessive bleeding and forestall atherosclerosis. However, these observations suggest that factor VII-mediated thrombin generation may proceed by partitioning of small amounts of factor VII on tissue factor-expressing cells and that factor VII contained within monocytes may facilitate tissue factor-induced coagulation by these cells. These features may provide efficient coagulation activation despite a deficiency of the plasma coagulant protein. The current results may explain, at least in part, the minimal bleeding tendency, and also the occurrence of thrombosis and atherosclerosis in certain persons with factor VII deficiency.

Aged↗
PubMed1982

Mechanical circulatory support via the left ventricular vent: the concept of left ventricular copulsation.

Left ventricular copulsation was evaluated as a means of circulatory support in an experimental canine cardiogenic shock preparation. Copulsation was effected by a commercially available pulsatile assist device which was attached to an apical left ventricular vent cannula. The hemodynamic effects were compared with those of intra-aortic balloon pumping (IABP) in the same animals. Copulsation produced a 35.6% increase in mean aortic blood pressure, a 32.3% reduction in mean left atrial pressure, a 66.7% increase in cardiac output, and a 76.2% increase in coronary blood flow. The improvement in these variables was significantly greater during left ventricular copulsation than during IABP (p less than 0.05). The method is simple, uses equipment that is readily available, and is potentially a powerful intermediate circulatory support modality between IABP and more complex techniques.

Animals↗
PubMed1979

Left ventricular mechanics of counterpulsation and left heart bypass, individually and in combination.

Counterpulsation and left heart bypass devices have been successfully used to salvage patients with severe left ventricular power failure following cardiopulmonary bypass. Each of these techniques is believed to reduce or minimize myocardial work, yet the effects of these devices on the force of myocardial contraction have not been defined. In the present investigation the effects of counterpulsation produced by intravascular (intra-aortic balloon pumping) and extravascular (pulsatile assist device) balloon devices, partial left atrial-aortic bypass, and total bypass on left ventricular mechanics were examined. The devices were studied individually and in combination in 10 anesthetized open-chest dogs. Left ventricular wall stress, external work, and contractility indices were calculated by computer using a changing volume spherical model of the left ventricle. Results indicate that although all currently available circulatory assist devices reduced peak left ventricular wall stress, a spectrum of relative effectiveness progressed from intra-aortic balloon pumping or pulsatile assist device alone through the combination intra-aortic balloon pumping plus the pulsatile assist device. Partial left heart bypass was more effective than intra-aortic balloon pumping plus the pulsatile assist device in reducing peak wall stress, but the difference was small. Total left heart bypass was vastly superior to any of the other modalities tested in its effects on peak wall stress as well as external work. The addition of counterpulsation to partial or total left heart bypass produced minimal changes in left ventricular systolic mechanics.

Animals↗