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Biomedical subjects

R H Breyer

Publications and source records attributed to R H Breyer.

At least 37 records · Page 2Linked to original sources
PubMed1986

Cardiac performance during reperfusion improved by pretreatment with oxygen free-radical scavengers.

We studied the effects of oxygen free radicals on cardiac performance during reperfusion of ischemic myocardium. The pig heart, isolated in situ, was subjected to 60 minutes of regional ischemia at normothermia by occlusion of the left anterior descending coronary artery followed by 60 minutes of hypothermic cardioplegic arrest and 60 minutes of normothermic reperfusion. The oxygen free-radical scavengers, superoxide dismutase and catalase, were administered before occlusion of the left anterior descending coronary artery in the experimental group. The generation of free radicals in the untreated group, estimated by the measurement of malondialdehyde in the perfusate, was significant during reperfusion and was associated with a corresponding increase in creatine kinase. Superoxide dismutase and catalase significantly slowed the appearance of malondialdehyde and the release of creatine kinase during reperfusion. Superoxide dismutase and catalase did not alter coronary flow and myocardial oxygen extraction or consumption during occlusion of the left anterior descending coronary artery; however, coronary flow and oxygen consumption were significantly higher (p less than 0.05) during reperfusion in hearts treated with antioxidants. Left ventricular developed pressure and its maximum first derivative were measured under isovolumic conditions. In the untreated group, left ventricular developed pressure and its maximum first derivative declined to 61.1% and 57.1% of baseline values, respectively, after 60 minutes' occlusion of the left anterior descending, and to 45% of baseline values after 15 minutes of reperfusion. The decline in left ventricular developed pressure and its maximum first derivative during reperfusion was significantly (p less than 0.05) inhibited by superoxide dismutase and catalase, but left ventricular end-diastolic pressure was not significantly altered. These results implicate oxygen-derived free radicals in the injury resulting from reperfusion of ischemic myocardium and suggest that oxygen free-radical scavengers effectively protect against such injury.

Animals↗
PubMed1985

Myocardial biopsy drill: construction details and techniques.

The modification of currently available dental equipment to construct a myocardial biopsy drill by the technique of Poole et al. (P. E. Poole, G. F. Norris, R. M. Lewis, and J. W. Covell, J. Appl. Physiol. 24: 832, 1968) is described. In dogs, five to seven full-thickness myocardial cores 3 mm in diameter and weighing 40 to 70 mg could be obtained consistently with the drill without affecting left ventricular function. The positive pressure/negative pressure system allowed separation of contaminating blood from the myocardial sample and rapid myocardial freezing. Assessment by a modification of the technique of Estabrook et al. (R. W. Estabrook, J. R. Williamson, R. Frenkel, and P. K. Maitra, In R. W. Estabrook and M. E. Pullman (Eds.), Methods in Enzymology, New York: Academic Press, 1967. Vol. 10, p. 474). yielded myocardial ATP levels of 32.12 +/- 0.90 nmole/mg of protein.

Adenosine Triphosphate↗
PubMed1985

Late postoperative tamponade following coronary artery bypass grafting in patients on antiplatelet therapy.

Myocardial revascularization was performed in 1,361 patients over a 66-month period (February, 1978 to August, 1983) without a single occurrence of late cardiac tamponade. During a subsequent 4-month-period, aspirin and dipyridamole were administered routinely to all coronary bypass patients. The incidence of late cardiac tamponade rose significantly (p less than 0.001) to 3 of 85 patients (3.5%). Routine perioperative administration of aspirin and dipyridamole to patients undergoing myocardial revascularization may be associated with an increased incidence of delayed cardiac tamponade.

Adult↗
PubMed1985

Phrenic nerve paresis associated with the use of iced slush and the cooling jacket for topical hypothermia.

Phrenic nerve injury has been reported with the use of iced slush for topical cardiac hypothermia. To study this problem in both valve and coronary procedures, we tried to detect phrenic nerve injury in five groups of patients undergoing cardiac operations in which different techniques of topical hypothermia were used. The results indicate a 24% incidence of left phrenic nerve paresis in patients undergoing coronary bypass with iced slush used for topical hypothermia, 12.5% in patients in whom the cardiac cooling jacket was used in association with cold saline, and 22.9% in patients in whom both the cardiac cooling jacket and iced slush were used in the pericardial sac. There was no phrenic nerve injury when saline alone was used. Phrenic paresis is transient and of no clinical significance except when bilateral. Avoidance of contact of either the cooling jacket or iced slush with the phrenic nerve could avoid this complication.

Cold Temperature↗
PubMed1985

Does the type of venous drainage or cardioplegia affect postoperative conduction and atrial arrhythmias?

Five consecutive patient groups undergoing coronary bypass surgery were studied for postoperative conduction disturbances and atrial arrhythmias. Group I (50 patients) had blood cardioplegic solution (25 meq/liter potassium) and unsnared venae cavae, group II (156 patients) had low-volume crystalloid cardioplegic solution (25 meq/liter potassium) and unsnared venae cavae, group III (56 patients) was similar to group II except that a single cavoatrial venous cannula was used instead of two separate cannulas, group IV (218 patients) had high-volume crystalloid cardioplegic solution (25 meq/liter potassium) and snared venae cavae, and group V (37 patients) was the same as group IV except that the cardioplegic solution contained 10 meq/liter potassium after the first dose, which contained 25 meq/liter. All postoperative electrocardiograms were analyzed for conduction disturbances and atrial arrhythmias. The results showed a significantly lower incidence of conduction disturbances in group I (12%) as compared with groups II to IV. In addition, groups IV and V (high-volume crystalloid cardioplegic solution) had a significantly higher incidence of conduction disturbances than groups II and III (lower-volume crystalloid solution) (55.0% and 62.1% vs 26.2% and 35.1%, respectively). The majority of these disturbances were temporary. Group I also had the lowest incidence of postoperative atrial arrhythmias (3.8%). There was no significant difference between the groups receiving high- and low-volume crystalloid solution. It is concluded that blood cardioplegic solution affords the best protection against postoperative conduction disturbances and atrial arrhythmias. High-volume crystalloid cardioplegic solution affords the least protection against conduction disturbances but has no effect on atrial arrhythmias.(ABSTRACT TRUNCATED AT 250 WORDS)

Arrhythmias, Cardiac↗
PubMed1985

Postinfarction angina: an expanding subset of patients undergoing coronary artery bypass.

An analysis of patients undergoing coronary artery bypass for unstable postinfarction angina (less than or equal to 30 days of infarct) during two time periods was undertaken: Group I, January, 1982, through December, 1982; Group II, September, 1983, through August, 1984. Clinical, angiographic, and operative data were coded, and statistical analysis was used to compare the two patient groups, evaluate operative results, and identify risk factors. The incidence of unstable postinfarction angina as an indication for bypass grafting increased significantly (p less than 0.01) from the first to the second time frame, 8.7% (24/276) to 18% (51/283). A greater proportion of Group II patients were operated upon within 7 days of infarct (37% versus 21%, p less than 0.01). All other variables examined were similar in the two patient groups. Analysis of the combined Group I and II patients (N = 75) indicates the following: The ratio of transmural to nontransmural infarction was 39%/61%, and 39% of patients had a previous infarction. Three-vessel disease was present in 76%, two-vessel in 21%, one-vessel in 3%, and left main disease in 20%. Left ventricular ejection fraction was greater than or equal to 40% in 27% of patients, less than 40% in 32%, and not obtained in 41%. Mean left ventricular end-diastolic pressure was 19.5 mm Hg. Intra-aortic balloon pumping was necessary preoperatively in 39%. The mean interval from infarction to revascularization was 12 days, and the mean number of grafts was 3.1 (range one to six). The overall in-hospital mortality was 8% (6/75). Statistical analysis demonstrated that decreased ejection fraction was associated with an increased risk of mortality. No other variables were correlated with mortality. Mean follow-up for the combined Group I and II patients is 13 months (range 4 to 32). Ninety percent of survivors remain in Canadian Heart Association Functional Class I and 6% in Class II. No late deaths have occurred. Patients with unstable postinfarction angina constitute an ever-increasing subset of the coronary bypass population of the 1980s. Operation can be performed with a satisfactory mortality and excellent long-term outlook compared to less acceptable published results with medical management alone. Preoperative left ventricular function constitutes the major indicator of operative risk.

Angina Pectoris↗
PubMed1985

A comparison of Cell Saver versus ultrafilter during coronary artery bypass operations.

A study was performed to evaluate two blood conservation techniques that can be used with high-volume crystalloid cardioplegia. Twenty-seven patients undergoing coronary artery bypass with high-volume crystalloid cardioplegia were randomized into two groups: In 12 Group I patients the coronary sinus effluent was drained into a Cell Saver and the recovered, washed red cells were then reinfused. In 15 Group II patients the coronary sinus effluent was absorbed systemically and excess volume was removed from the cardiopulmonary bypass circuit by an ultrafilter. These two groups were compared with a retrospective control group in which the cardioplegic solution had been evacuated from the right atrium and discarded. Both the techniques resulted in significant and equivalent red blood cell conservation compared with the retrospective control group. The ultrafilter was associated with less derangement of prothrombin time. More complete potassium removal was provided by the Cell Saver.

Blood↗
PubMed1985

Short term survival following perfusion with fluosol-DA for cardiopulmonary bypass.

Seven dogs were perfused on cardiopulmonary bypass for one hour using a perfusate which included one liter of Fluosol in order to investigate tissue oxygenation during perfusion as well as possible biochemical and histopathologic effects of Fluosol on various organs. Tissue oxygenation during cardiopulmonary bypass was evaluated by measuring arterial and venous oxygen tensions as well as oxygen content and arterial pH. Biochemical studies were measured pre and post bypass and were followed up to 48 hours following discontinuation of cardiopulmonary bypass. The animals were observed clinically for evidence of abnormal behavior during 30 days of follow-up and were then sacrificed. Biopsies from the heart, lung, liver, spleen, kidney and brain were examined by light and electron microscopy. Excellent tissue oxygenation and normal acid base status was seen uniformly during cardiopulmonary bypass. Clinical status and biochemical parameters remained normal during followup. Histopathologic examination revealed only a marked increase in phagocytic histiocytes in the reticuloendothelial system of liver and spleen with sinusoidal compression but no functional impairment.

Animals↗
PubMed1984

A prospective study of sternal wound complications.

Eight hundred seventy patients were enrolled in a prospective study to identify risk factors for sternal wound complications following open-heart operations. The 0.8% incidence of major sternal complications was similar to that reported in the literature by other centers. The effects of age, sex, weight, operative time, type of procedure, resident versus attending surgeon, prolonged ventilatory support, reoperation for bleeding, external cardiac massage, and Dacron versus wire suture for sternal closure were assessed by stepwise logistic regression. Prolonged ventilation and female sex both strongly increased the risk of major sternal complications. Age and weight exerted lesser, but statistically significant, effects on the incidence of such complications. None of the other factors was associated with an increased risk of major sternal complications.

Adolescent↗
PubMed1984

Rebound vasospasm after coronary revascularization in association with calcium antagonist withdrawal.

Four patients experienced life-threatening coronary vasospasm following discontinuation of calcium channel blocking medication at the time of coronary revascularization. The last dose of the calcium blocker in each instance was administered between 8 and 18 hours before operation. Two of the patients were receiving diltiazem (60 mg four times a day) and 2, nifedipine (20 mg four times a day). During this same period, 16 patients had received diltiazem (12.5% incidence of vasospasm) and more than 100 patients, nifedipine (less than 2% incidence). In 3 of the 4 patients, coronary spasm was identified by electrocardiogram and documented as the cause of ischemia in the distribution of a nondiseased right coronary artery. In the fourth patient, spasm had occurred in the distribution of a bypassed left anterior descending coronary artery. In 2 patients in whom the problem was recognized retrospectively, an infarct developed; 1 patient died. In the 2 patients in whom the problem was apparent prior to infarction, nitroglycerin (1 to 3 micrograms/kg/min, intravenously) and nifedipine (10 mg, sublingually every 4 to 6 hours) successfully reversed the ischemic process. The routine administration of calcium at the completion of coronary revascularization may be ill-advised in patients in whom calcium channel blockers have been utilized. Postoperative therapy of this condition with intravenous administration of nitroglycerin and sublingual administration of nifedipine seems to be effective when instituted early.

Adult↗
PubMed1984

Computed tomography for evaluation of mediastinal lymph nodes in lung cancer: correlation with surgical staging.

Computed tomography (CT) of the chest (late model) was done preoperatively in 56 candidates for resection of lung cancer. Precise borders for each node region were defined by the American Thoracic Society modification of the classification of the American Joint Committee for Cancer Staging and were used to "map" nodes seen on CT and nodes removed surgically. Metastatic involvement of mediastinal nodes was proven by mediastinoscopy in 11 patients; nodes were removed from multiple regions at thoracotomy in 45 patients. The mediastinum was clearly delineated by CT in 46 patients with determinate scans and was judged normal in 32 (CT-negative scans) and abnormal in 14 (CT-positive scans). A node was considered metastatically involved if it measured greater than 1.5 cm in diameter. Positive nodes were found at surgical staging in 3 of 32 patients with CT-negative scans and in all patients with CT-positive scans. Thus, for the 46 patients with determinate scans, sensitivity was 82%, specificity was 100%, and accuracy (true positive and true negative) was 93%. The high accuracy of CT in these patients suggests that mediastinoscopy is not necessary before thoracotomy in the patient with a CT-negative scan, but that for the patient with a CT-positive or CT-indeterminate scan, the indications for mediastinoscopy remain the same.

Adenocarcinoma↗
PubMed1983

Surgical implications in malignant cardiac disease.

Despite the rarity of primary malignant tumors of the heart (0.0017 to 0.03% of large postmortem series) and the infrequency of clinical signs and symptoms (0 to 50%) of the more common metastatic cardiac tumors, many cardiothoracic surgeons at some time will encounter a patient with one of these two conditions. A review of the medical literature yielded 28 cases of primary cardiac tumors, 10 of secondary tumors, and 12 of carcinoid heart disease treated surgically and followed sufficiently for retrospective evaluation. We summarized those cases and made the following conclusions. Primary malignant tumors of the heart are occasionally resectable, although cure is unlikely; survival may be enhanced by postoperative irradiation but probably not by postoperative chemotherapy. For patients with secondary malignant tumors of the heart, surgical intervention is rarely of benefit except for establishing a tissue diagnosis, effecting artificial cardiac pacing, decompressing symptomatic pericardial effusions, or reducing an obstructive tumor mass. Patients with carcinoid heart disease affecting the valves may derive benefit from valve replacement or repair. Thus, in selected patients with malignant cardiac disease, surgical intervention may be feasible and should always be among the therapeutic options considered.

Adult↗
PubMed1983

Measurement of extravascular lung water in sheep during colloid and crystalloid resuscitation from smoke inhalation.

The pathophysiology of pulmonary inhalation injury, a major cause of morbidity and mortality from fires, is poorly understood. To examine the effects of colloid and crystalloid resuscitation on extravascular lung water (EVLW) during a standard smoke inhalation injury, we subjected 12 sheep to 8 minutes of cool pine smoke inhalation. The animals were then resuscitated to a pulmonary capillary wedge pressure (PCWP) of 10 +/- 1.5 mm Hg with either lactated Ringer's solution or plasma protein derivative. EVLW, cardiac output, vascular resistance, colloid oncotic pressure (COP), arterial and pulmonary artery pressures, PCWP, and blood gases were monitored during 4 hours of resuscitation. In colloid-treated animals, EVLW increased from 8.3 +/- 1.2 to 11.1 +/- 0.9 ml/kg with injury; it increased only to 12.5 +/- 1.3 ml/kg during resuscitation. In crystalloid-treated animals, EVLW increased from 8.0 +/- 1.0 to 10.3 +/- 0.8 ml/kg with injury and further increased to 17.4 +/- 1.6 ml/kg during resuscitation, a level significantly higher than that in the colloid group (P less than 0.05). The increases in EVLW were associated with progressive hypoxia, which was worse in the crystalloid group. In the crystalloid group, COP decreased from 27.3 +/- 0.9 to 14.2 +/- 0.4 mm Hg and intravascular driving force (COP-PCWP) dropped from 17.6 to 3.26 +/- 1.5 mm Hg; COP and COP-PCWP were maintained in the colloid group. These data demonstrate that supporting serum COP minimizes the increase in EVLW with smoke inhalation injury and suggests that smoke inhalation does not lead to a dramatic increase in alveolar capillary membrane permeability to protein.

Animals↗
PubMed1983

Digoxin and propranolol in the prophylaxis of dysrhythmias after coronary artery bypass grafting.

Serious tachydysrhythmias occur in 10% to 30% of patients early after coronary artery bypass grafting (CABG). We studied the effects of digoxin and propranolol in preventing these dysrhythmias over the first week after CABG (average number of grafts, 2.7/patient). Consecutive patients (n = 179) undergoing CABG were randomized to a drug (group 1) or a control (group 2) group. Excluded were patients given digoxin before CABG and those with ejection fractions of less than 40%, those with dysrhythmias within 18 hr after CABG, those being pacer dependent, and those with low-output syndrome after CABG. Risk factors were comparable in both groups. Electrocardiographic examination showed perioperative myocardial infarction in five patients (2.8%). Digoxin (1 mg iv given over 24 hr, then 0.25 mg/day) and propranolol (10 mg given every 6 hr) were started 6 hr after CABG. Supraventricular dysrhythmias requiring treatment occurred in 3.4% of 89 group 1 patients and in 30% of 90 group 2 patients (p less than .001); ventricular dysrhythmias occurred in 1.1% of group 1 and 8.9% of group 2 patients (p less than .01). In this study, a regimen of post-CABG digoxin and propranolol significantly reduced the incidence of supraventricular and ventricular dysrhythmias without causing adverse reactions.

Aged↗