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Biomedical subjects

P M Scholz

Publications and source records attributed to P M Scholz.

8 recordsLinked to original sources
PubMed1992

Fibrinolytic drugs prevent pericardial adhesions in the rabbit.

Epicardial adhesions are believed to form secondarily to impaired pericardial fibrinolytic activity. This activity was reconstituted in a rabbit pericardial adhesion model with single doses of the fibrinolytic agents tissue plasminogen activator (t-PA), t-PA analog (Fb-Fb-CF), and streptokinase (SK), resulting in reductions in the extent and tenacity of adhesion formation. Adhesions of the median strip of the anterior cardiac surface were reduced in area from 89% (n = 22) in controls, to 28% (n = 5) by treatment with Fb-Fb-CF (0.94 mg), and to 49% (n = 7) by treatment with SK (93,750 IU). A modified fabric of oxidized regenerated cellulose (mTC7) used to deliver the agent to the cardiac surface did not interfere with the activity of these agents (Fb-Fb-CF 19%, n = 14; SK 33%, n = 7). t-PA (0.94 mg) was also found to reduce adhesion formation in combination with mTC7 (4%, n = 4), although the appearance of significant postoperative bruising and bleeding resulted in a decision to terminate the treatment of further animals with t-PA with and without mTC7. Postoperative bruising, bleeding, and swelling, to a lesser extent, were associated with SK and Fb-Fb-CF. Despite the efficacy of the these fibrinolytic drugs further work is required to assess their safety before they are used clinically.

Animals↗
PubMed1978

Cardiac function at rest and during exercise in normals and in patients with coronary heart disease: evaluation by radionuclide angiocardiography.

This study demonstrates that radionuclide angiocardiography provides a simple and noninvasive approach for evaluation of myocardial function. Previous work concerning myocardial performance has been generally conducted with the patient in the supine position. Radionuclide angiocardiograms were performed in the present study at rest and during exercise in 30 normal subjects and in 30 patients with ischemic coronary artery disease. There were 30 normal controls (Group I), ten with single coronary artery disease (Group II), and 20 patients with multiple vessel coronary disease (Group III). All subjects were studied in the erect posture on a bicycle ergometer. In the normal controls, the mean heart rate doubled and the cardiac output tripled during exercise. Intensive training can lead to extraordinary levels of cardiac performance as shown in a world-class athlete who during peak exercise attained a heart rate of 210, an ejection fraction of 97%, and a cardiac output of 56 litres per minute. In the patients with coronary artery disease, both groups, were able to increase cardiac output to approximately twice the resting value. The magnitude of increase in blood pressure during exercise was not significantly different in the three groups. However, definite changes were present in the end-diastolic volume at rest was 116 and rose to 128 ml in Group I, 93 rising to 132 ml in Group II, and 138 increasing to 216 ml in Group III. The stroke volume increased comparably in all three groups, but the ejection fraction from rest to exercise showed a marked contrast in the controls compared to those with multivessel coronary disease. The ejection fraction rose in Group I from 66 to 80% during exercise, while in Group II it fell from 69 to 67%, and in Group III from 60 to 46%. These findings indicate that patients with ischemic myocardial disease respond to the stress of exercise by cardiac dilatation to maintain of increase stroke volume at increased heart rates. Moreover, the magnitude of this response appears to be greatest in patients with left main coronary artery stenosis. This approach for evaluating myocardial function during exercise provides useful data of importance in selecting medical versus surgical management of patients with ischemic coronary artery disease.

Adult↗
PubMed1975

Correlation of blood rheology with vascular resistance in critically ill patients.

Blood rheologic measurements together with peripheral resistance determinations in vivo were made in 27 critically ill patients. Eighteen of these patients (group I) suffered from violent trauma or operative injury and the other 9 (group II) were patients with generalized sepsis. As a result of fluid therapy all patients underwent hemodilution, resulting in a decrease in blood viscosity. This drop in blood viscosity was counteracted to some extent by an increased plasma viscosity due to elevated fibrinogen levels and a decreased red cell deformability associated with massive transfusions of stored blood. The correlation of vivo hemodynamics with blood rheological data made it possible to separate the relative roles of vascular dimensions and blood viscosity in affecting the total peripheral resistance. This approach permitted us to distinguish varying degrees of vasoconstriction in nonseptic patients in low flow states (group I) and varying degrees of vasodilation in septic patients (group II). This type of analysis serves to elucidate the pathophysiology of hemodynamic alterations in disease and provides a rational basis for devising an effective therapeutic program.

Acute Disease↗
PubMed1975

Effects of major abdominal operations on human blood rheology.

Serial blood rheological measurements were systematically carried out in 14 patients undergoing major elective abdominal operations for a period up to 10 days after operation. The measurements included blood viscosity over a wide range of shear rates (0.01 to 208 sec.-minus 1), hematological data, and plasma protein concentrations. Significantly elevated plasma viscosity preoperatively accounted for a normal blood viscosity in the presence of anemia. After an initial drop due to hemodilution lasting for 1 to 3 days after operation, blood viscosity returned to normal by the tenth postoperative day. This was the result of an increased plasma viscosity, primarily due to rise in plasma fibrinogen and alpha2- and beta2-globulin concentrations. The red cell deformability of these patients was normal except for one patient who received seven units of transfused blood. The results of this investigation suggest that abnormal rheological properties of blood and plasma should be considered in therapeutic attempts to improve microcirculatory flow and oxygen delivery to tissues.

Abdomen↗