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Biomedical subjects

R L Replogle

Publications and source records attributed to R L Replogle.

At least 37 records · Page 2Linked to original sources
PubMed1983

Long-term evaluation of pericardial substitutes.

The development of postoperative pericardial adhesions increases the risk of cardiac reoperations because of the danger of damaging the heart, great vessels, or grafts. Several pericardial substitutes have been tested in the past in an attempt to facilitate reoperation, with inconclusive results. This study evaluated eight different materials as pericardial substitutes: six synthetic materials and two different preparations of bovine pericardium. In 32 dogs a 10 by 5 cm piece of pericardium was excised through a right thoracotomy and the defect closed with a measured patch. Each material tested was implanted in four dogs that were put to death at 3, 6, 9, and 12 months. At autopsy the development of adhesions and epicardial reaction were graded as none, minimal, moderate, and severe. Histologic studies of the patch, the epicardium, and the suture line were performed. Our results suggest that both types of bovine pericardium were an excellent substitute. Although minimal adhesions developed, these were easily dissected. The underlying anatomy was clearly recognizable because of the lack of epicardial reaction. Silicone rubber-coated polyester fabric was an acceptable material for the prevention of adhesions, but a severe fibrous epicardial reaction impeded the recognition of the coronary arteries. Both silicone-filled and high-porosity polytetrafluoroethylene (PTFE) films reduced adhesions but caused a severe epicardial reaction. The other synthetic materials were considered inferior because of severe epicardial reaction and/or structural deterioration.

Animals↗
PubMed1982

The effects of thermal injury on rat skeletal muscle microcirculation.

An intravital microscopic study of rat skeletal muscle microvasculature was undertaken to assess changes in peripheral blood flow distant from thermal injury following burning. We found a significant increase in RBC velocity and quantitative flow in arterioles of animals with major thermal injury (28% TBSA full-thickness burn) compared to flow in animals with minor burns (18% TBSA) and control animals. There was no evidence for arteriolar diameter changes, erythrocyte sludging, or leukocyte-endothelial adherence. Major thermal injury is associated with an increase in skeletal muscle arteriolar blood flow distant from the site of injury.

Animals↗
PubMed1982

Traumatic avulsion of the innominate and left carotid arteries: successful repair.

Traumatic rupture of the aorta or the arch vessels is a rare and frequently fatal injury. This lesion should be considered in all cases of severe chest trauma. Early aortography is essential for accurate diagnosis. Nineteen cases of avulsion of the innominate artery have been previously reported. In only two of them a second aortic arch branch had an associated injury. The case presented here is the first successful repair of a combined avulsion of both the innominate and the carotid arteries from the aortic arch. Cerebral circulation was maintained during the operation with a heparin-coated shunt from the ascending aorta to the right common carotid artery. Reconstruction was accomplished by inserting a bifurcated Dacron prosthesis from the aorta to the innominate and left carotid arteries. The use of a heparin-bonded shunt maintained cerebral perfusion, and greatly simplified the operation and avoided the risk of extracorporeal circulation and systemic anticoagulation in a patient with multiple trauma.

Adult↗
PubMed1982

Changes in indications for heart transplantation. An additional argument for the preservation of the recipient's own heart.

The 1 year survival rate after heart transplantation since 1967 from +/-30% to +/-70%, and the 5 year survival rate is now +/-50%. This improvement has brought renewed interest in this procedure, now done in about twenty centers in eight countries, and increased confidence has widened the indication to patients who are less than terminally ill, to restore quality of life. This trend is illustrated by the Cape Town series, which can be divided into two parts: 10 patients treated by orthotopic heart transplantation (OHT), from 1967 to 1973, and 40 patients treated by heterotopic heart transplantation (HHT), from 1974 to 1981. The HHT group was younger (mean 37 +/- 10 years versus 51 +/- 9 years, p less than 0.001), had been ill for a shorter length of time (mean 3.6 +/- 0.7 years versus 6.6 +/- 1.4 years, p less than 0.091), and were in a lower New York Heart Association (NYHA) class (mean 3.45 +/- 0.11 versus 3.9 +/- 1.0, p less than 0.006). The improved survival is linked to patient selection, progress in management, and switch to HHT, but not to progress in matching between donor and recipient. Since there is no means to predict tolerance of the donor heart, HHT limits the risks from unforseeable mismatch. The recipient's heart is a built-in assist device, maintaining life when the donor heart fails acutely at operation or during acute [three cases] or chronic [two cases] rejection. Had these patients undergone OHT they would have died. Comparing the 10 oldest HHT patients with the OHT series, no difference in pretransplant parameters was found. However, survival of HHT recipients was longer during the critical post-HHT period: at 3 months, p less than 0.011; at 6 months, p less than 0.05. Larger series will separate the effects of progress in management from the intrinsic advantages of HHT. Retaining the recipient's heart is logical and has brought few complications. Survival rate of 40 HHT patients was 73% at 6, 65% at 12, and 51% at 36 months; 85% of survivors are in NYHA Class I. In patients in less than desperate condition, but who refuse to remain cripples, HHT eliminates the growing ethical problem of removing a recipient's heart that may still support the patient.

Adolescent↗
PubMed1981

Reduction of myocardial infarct size in swine: a comparative study of intraaortic balloon pumping and transapical left ventricular bypass.

This study compared intraaortic balloon pumping (IABP) and transapical left ventricular (LV) bypass for their effectiveness in reducing infarct size in swine. In 28 pigs (25.4 +/- 4.7 kg) the left anterior descending coronary artery was ligated distal to the first diagonal branch. Nine animals served as controls. Nine animals were treated with IABP and the remaining 10, with transapical bypass. Ten animals-3 control, 3 IABP, and 4 transapical bypass--died prior to completion of the study, thereby resulting in 6 animals in each group. Both assist devices were begun 45 minutes after coronary ligation, this being as rapid as mechanical intervention could be accomplished in the patient after infarction. With transapical LV bypass, 70 to 100% bypass was accomplished and the LV systolic pressure remained in the range between mean aortic pressure and 30 mm Hg less than that. All animals were killed after 24 hours. The hearts were excised and stained with nitroblue tetrazolium, and infarct size was quantitated in grams of infarct per 100 gm of LV and septal mass. After 24 hours the mean aortic pressure was 73 +/- 12 mm Hg in controls, 105 +/- 20 mm Hg in animals with IABP (p less than 0.01), and 91 +/- 13 mm Hg in those with transapical LV bypass (p less than 0.05). The infarct size was 22.7 +/- 4.9 gm per 100 gm of LV and septal mass in control animals. With IABP, the infarct size was nonsignificantly changed to 19.4 +/-5.9 gm per 100 gm (p greater than 0.3). With transapical LV bypass, the infarct size was significantly reduced to 15.9 +/- 3.5 gm per 100 gm (p less than 0.025). This represented a 30% reduction of infarct size from controls. These results demonstrate that despite hemodynamic improvement with IABP, transapical LV bypass is necessary to markedly decrease myocardial work and significantly reduce infarct size.

Animals↗
PubMed1981

Effect of coronary artery reperfusion on infarct size in swine.

Several authors have reported a low mortality and salvage of ischemic myocardium in patients undergoing coronary revascularization after recent myocardial infarction. In this study, 20 surviving pigs with a coronary circulation similar to that of man were divided into two groups of 10 animals each. In the first group, the left anterior descending coronary artery (LAD) was ligated just beyond the first diagonal branch. Five animals were put to death at 24 hours and the remaining five animals, at 7 days. In the other group of 10 animals, the LAD was occluded just beyond the first diagonal branch and reperfused 3 hours after occlusion. Five of these animals were put to death at 24 hours and the remaining five animals, at 7 days. The left atrial pressure (LAP), heart rate, mean arterial pressure (MAP), and cardiac output were continuously monitored. Myocardial infarct size was determined planimetrically after the myocardium was sliced and stained with nitroblue tetrazolium. In five animals subjected to ligation for 24 hours, myocardial infarct size was 20.3 +/- 0.53 standard error mean (SEM) grams infarct per 100 gm left ventricular and septal mass (gm/100 gm LVS). In five animals subjected to occlusion, reperfusion in 3 hours, and death at 24 hours, the infarct size was 22.9 +/- 1.7 SEM gm/100 gm LVS. At 1 week in the ligated animals the infarction decreased to 15.5 +/- 1.7 SEM gm/100 gm LVS. In the reperfused animals at 1 week the infarction size was 14.5 +/- 1.7 SEM gm/100gm LVS. There was no significant difference in these values (Student's t test). Light and electron micrographs demonstrated hemorrhagic necrosis in every instance with reperfusion. Cardiac output, LAP, and MAP remained unchanged after reperfusion. These data suggest that in human beings without well-developed inherent collaterals sustaining myocardial infarction with coronary occlusion, that reperfusion as early as 3 hours after infarction would not be beneficial.

Animals↗
PubMed1980

Aberrant left pulmonary artery (pulmonary artery sling): successful repair and 24 year follow-up report.

A case of anomalous left pulmonary artery arising from the right and coursing behind the trachea and anterior to the esophagus (pulmonary artery sling) is reported. The therapy currently advocated for this disorder is ligation of the anomalous vessel and performance of a left pulmonary to main pulmonary arterial anastomosis anterior to the trachea. A median sternotomy incision allows total mobilization of the anomalous vessel, minimizes respiratory embarrassment and aids in performance of the anastomosis. In the present case, a postoperative pulmonary angiogram revealed a patent left pulmonary artery, the second reported instance of such patency. The first successful repair of pulmonary artery sling was reported by Potts and colleagues in 1954. After a 24 year follow-up period their patient has normal exercise tolerance and no perfusion to the left lung is evident on ventilation-perfusion scan.

Airway Obstruction↗
PubMed1980

Cardiovascular effects of experimental cerebral missile injury in primates.

Ten rhesus monkeys were subjected to detailed cerebral and cardiac monitoring over a period of 90 minutes following an experimental gunshot wound. Bradycardia, decreased cardiac output, and decreased pulmonary and systemic blood pressures were observed in the presence of normal preloading (right and left atrial pressures) and afterloading (pulmonary and systemic vascular resistances). Defective cardiac output, autoregulation and cerebrovascular resistance were associated with low perfusion pressures, low cerebral blood flow, and low CMRO2.

Animals↗
PubMed1980

Steroids in heart surgery: a clinical double-blind and randomized study.

The role of steroids in heart surgery was assessed in a group of 95 patients undergoing cardiopulmonary bypass. The treated group (47 patients) received repeated doses (every six hours) of methylprednisolone (30 mg/kg IV) in a double-blind, randomized fashion. The control group (48 patients) received a placebo in a fashion identical to the treated group. There were no significant (P less than 0.1) hemodynamic or biochemical differences between the control group and the patients receiving methylprednisolone. An improvement in survival was observed in the group receiving methylprednisolone. This finding cannot be explained with the data obtained from this study, in particular, when no other biochemical findings were improved. A more exhaustive hemodynamic and biochemical analysis is necessary to understand the subtle changes that are incurred with the use of steroids for heart surgery.

Adolescent↗
PubMed1980

Failure of intra-aortic balloon pumping to reduce experimental myocardial infarct size in swine.

Although intra-aortic balloon pumping (IABP) is reported to reduce myocardial infarct size in dogs, this phenomenon may be due to pre-existing collaterals in this species. Pigs more closely approximate human coronary anatomy, having poor inherent collateralization. This study evaluates hemodynamic changes and quantitates myocardial infarct size 24 hours after coronary occlusion in swine, with and without IABP. Eighteen pigs underwent ligation of the left anterior descending coronary artery distal to the first diagonal branch: Nine were treated with IABP beginning 45 minutes after coronary occlusion and nine served as control subjects. Three in each group died prior to completion of the study. In both groups myocardial infarction resulted in a significant (p less than 0.05) decrease of cardiac output (28.5%) and mean aortic pressure (p less than 0.05) improvement of mean aortic pressure (4 to 7%) during the switch on period. After 24 hours, mean aortic pressure in IABP-treated animals (105 +/- 20 mm Hg) was significantly (p less than 0.01) higher than in control pigs (73 +/- 12 mm Hg). Myocardial infarct size as detected by staining with nitroblue tetrazolium was 22.7 +/- 4.9 gm infarct/100 gm left ventricular and septal mass in control pigs and 19.4 +/- 5.9 gm infarct/100 gm left ventricular and septal mass in treated animals (p less than 0.3). In conclusion, IABP, despite significantly improving circulatory parameters, does not significantly reduce the size of an acute myocardial infarction after coronary ligation in swine.

Animals↗