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Biomedical subjects

N O Fowler

Publications and source records attributed to N O Fowler.

At least 37 records · Page 2Linked to original sources
PubMed1985

M-mode echocardiography in constrictive pericarditis.

M-mode echocardiograms from 40 patients with proven constrictive pericarditis and 40 subjects without evidence of cardiac disease were reviewed for features previously described in constrictive pericarditis. In this large series, no single feature of the M-mode echocardiogram could be considered diagnostic, although a pattern of normal left ventricular size and systolic function, mild left atrial dilation, flattened diastolic left ventricular posterior wall motion and abnormal septal motion was found in most patients. It is concluded that the M-mode echocardiogram can provide findings suggestive of constrictive pericarditis but must be used in conjunction with hemodynamic and other studies to establish the diagnosis.

Echocardiography↗
PubMed1985

The hemodynamic effects of cardiac tamponade: mainly the result of atrial, not ventricular, compression.

We studied the hemodynamic effects of surgically induced regional cardiac tamponade in anesthetized dogs. Tamponade restricted to either the right or the left ventricle was compared with tamponade of either ventricle and both atria. Intrapericardial pressures were elevated to approximately 20 mm Hg. With tamponade of the right ventricle alone, aortic pressure rose from 161 +/- 3.8 to 164 +/- 3.4 mm Hg (p greater than .05) and cardiac output fell from 149.4 +/- 16.1 to 134.9 +/- 11.9 ml/kg/min (p greater than .05). However, tamponade of the right ventricle plus both atria decreased mean aortic pressure from 152.5 +/- 3.6 to 115.9 +/- 8.7 mm Hg (p less than .01) and cardiac output fell from 118 +/- 14.8 to 38.9 +/- 4.8 ml/kg/min (p less than .01). With tamponade of the left ventricle alone, aortic mean pressure changed significantly from 158.5 +/- 6.1 (control) to 148.9 +/- 5.0 mm Hg (tamponade) (p less than .05) and cardiac output was 135.5 +/- 28.3 (control) and 111 +/- 24.7 ml/kg/min (tamponade) (p greater than .05). However, when the atria were included, mean aortic pressure fell significantly more from 155.5 +/- 5.4 to 105.5 +/- 10.4 mm Hg (p less than .01) and cardiac output fell from 142.2 +/- 16 to 47.8 +/- 6.4 ml/kg/min (p less than .01). Atrial pressure rose when the atria were included, but not with tamponade of the left ventricle alone. Right but not left atrial pressure rose slightly with isolated right ventricular tamponade. We conclude that the principal hemodynamic effects of cardiac tamponade are not the result of compression of either the right or the left ventricle, but are the consequence of compression of the atria and/or the venae cavae and the pulmonary veins.

Animals↗
PubMed1984

Right heart catheter lesions: any significance?

In order to determine whether endocardial lesions that developed in relation to an indwelling catheter in the right heart had any significance or characteristics, a study with clinicopathologic correlations was performed in which a total of 57 hearts were found to have right heart endocardial lesions at necropsy. Some of our findings fall within the range of results of various similar studies, e.g., clinical backgrounds and incidence in which these lesions occur. However, others do not; pulmonary embolism was preexisting and coexisting rather than attributable to the heart lesions. Right heart lesions occur significantly more often (P less than 0.01) in patients who received a right heart catheter than those who did not. The morphologic features of these endocardial lesions are sufficiently characteristic to indicate not only that an intracardiac catheter had been present but even what type of catheter it was. Infective endocarditis was found in seven catheterized patients. This process has a tendency to involve valves transmurally, indicating possible need for prosthetic valve replacement if any patients were to survive the underlying disease. Traumatic perforation of the endocardium was uncommon. With the aid of careful indications and strict adherence to guidelines, the risk of fatality from these lesions is extremely unlikely.

Adult↗
PubMed1983

Hemodynamic and regional blood flow distribution responses to dextran, hydralazine, isoproterenol and amrinone during experimental cardiac tamponade.

Four different interventions were examined in dogs with cardiac tamponade. Infusion of 216 to 288 ml saline solution into the pericardium reduced cardiac output from 3.5 +/- 0.3 to 1.7 +/- 0.2 liters/min as systemic vascular resistance increased from 4,110 +/- 281 to 6,370 +/- 424 dynes . s . cm-5. Left ventricular epicardial and endocardial blood flows were 178 +/- 13 and 220 +/- 12 ml/min per 100 g, respectively, and decreased to 72 +/- 14 and 78 +/- 11 ml/min per 100 g with tamponade. Reductions of 25 to 65% occurred in visceral and brain blood flows and in a composite brain sample. Cardiac output during tamponade was significantly increased by isoproterenol, 0.5 microgram/kg per min intravenously; hydralazine, 40 mg intravenously; dextran infusion or combined hydralazine and dextran, but not by amrinone. Total systemic vascular resistance was reduced by all interventions. Left ventricular epicardial flow was increased by isoproterenol, hydralazine and the hydralazine-dextran combination. Endocardial flow was increased by amrinone and the combination of hydralazine and dextran. Right ventricular myocardial blood flow increased with all interventions except dextran. Kidney cortical and composite brain blood flows were increased by both dextran alone and by the hydralazine-dextran combinations. Blood flow to small intestine was increased by all interventions as was that to large intestine by all except amrinone and hydralazine. Liver blood flow response was variable. The most pronounced hemodynamic and tissue perfusion improvements during cardiac tamponade were effected by combined vasodilation-blood volume expansion with a hydralazine-dextran combination. Isoproterenol had as dramatic an effect but it was short-lived. Amrinone was the least effective intervention.

Aminopyridines↗
PubMed1983

Electrocardiographic and hemodynamic changes in experimental right ventricular infarction.

To investigate the electrocardiographic and hemodynamic changes in isolated right ventricular infarction, 0.25 ml or 0.5 ml of metallic mercury was injected into the right coronary artery of 14 closed-chest dogs. At autopsy, at least 60% of the right ventricle was necrotic in every dog. Hemodynamic observations were made in 11 and electrocardiographic mapping was performed in all 14 dogs. Right atrial pressure rose in 10 and left atrial pressure in nine of the 11 dogs; early right atrial pressure did not exceed left atrial pressure, but late right atrial pressure was greater in four dogs. Although cardiac output and blood pressure fell significantly, circulation was maintained. Twelve of 14 dogs had transient ST-segment elevation in the right precordial leads, and 12 developed right bundle branch block. Abnormal Q waves or R waves of 1 mm or less appeared in the right precordial leads in 13 of the 14 dogs. Since right bundle branch block and abnormal Q waves in the right precordial leads have not been recognized as useful signs in human right ventricular infarction, further investigations are warranted to determine their value in clinical applications.

Animals↗
PubMed1982

Constrictive pericarditis: new aspects.

The current status of constrictive pericarditis is reviewed with regard to its etiology, physical signs, electrocardiographic findings, and hemodynamic features. Angiographic aspects are also presented. The role and limitations of M-mode echocardiography in this disease are emphasized. The value of other noninvasive studies such as measurement of systolic time intervals, myocardial scanning, and high-speed echocardiography is described. Emphasis is placed on the invasive and noninvasive methods that may be useful in separating restrictive cardiomyopathy from constrictive pericarditis. Methods of treatment, indications for pericardial resection, and the current operative results are commented on briefly.

Angiocardiography↗
PubMed1981

Electrocardiographic diagnosis of right ventricular infarction.

The electrocardiographic findings in 11 cases of acute right ventricular infarction associated with acute left ventricular inferior wall myocardial infarction are described. The diagnosis of right ventricular infarction was proved by autopsy findings in five cases and supported by hemodynamic data in the other six. Ten of the 11 patients had typical electrocardiographic changes of acute inferior myocardial infarction and one had that of inferior wall injury. Transient S-T segment elevation was present in one (lead V1) or more of the right precordial leads in eight cases. In the absence of other explanations for the S-T segment elevation, acute right ventricular infarction was most likely the cause. Therefore, when acute inferior myocardial infarction is accompanied by S-T segment elevation in the right precordial leads, the coexistence of right ventricular infarction should be suspected. The sensitivity and specificity of this electrocardiographic sign are yet to be determined.

Aged↗
PubMed1981

Cardiac tamponade in medical patients.

We reviewed the cases of 56 medical patients wih cardiac tamponade who were treated at the University of Cincinnati. A paradoxic arterial pulse was critical in the diagnosis because most patients did not have a small quiet heart, and blood pressure was often well maintained. Fifty-two of 55 patients had enlarged cardiac silhouette by chest radiogram; heart sounds were diminished in 19 patients; arterial systolic pressure was greater than or equal to 100 mm Hg in 35, and arterial pulse pressure was greater than or equal to 40 mm Hg in 27. Echocardiograms in 23 patients showed abnormally increased right ventricular dimensions and decreased left ventricular dimensions during inspiration, except in one patient with left ventricular dysfunction. The causes of cardiac tamponade were metastatic tumor in 18 patients, idiopathic pericarditis in eight and uremia in five; five cases of tamponade occurred after heparin administration in acute cardiac infarction. Myxedema and dissecting aneurysm each caused tamponade in two patients. Pericardiocentesis relieved tamponade initially in 40 of 46 patients; however, two suffered fatal complications. Pericardial resection was done in 18, including 12 of these 46.

Adolescent↗
PubMed1980

Echocardiographic study of the paradoxical arterial pulse in chronic obstructive lung disease.

In nine subjects with chronic obstructive pulmonary disease (COPD) and pulsus paradoxus, M-mode echocardiograms showed inspiratory augmentation of right ventricular dimensions and inspiratory decrease of left ventricular diastolic dimensions. In five subjects in whom the echocardiographic transistor was in the subxiphoid position, mean right ventricular dimensions increased during inspiration from 1.4 +/- 0.20 to 2.96 +/- 0.38 cm (p < 0.01). With inspiration, mean left ventricular diastolic dimensions decreased from 4.8 +/- 0.61 to 3.7 +/- 0.63 cm (p < 0.01) in these five subjects. Two-dimensional echocardiograms, performed in three subjects, confirmed inspiratory augmentation of right ventricular cross-sectional area. Similar changes were produced in two normal volunteers by artificial obstruction to breathing. Left ventricular ejection time measurements demonstrated an inspiratory decline in left ventricular stroke volume. Inspiratory filling of the right ventricle is not hampered, but rather is exaggerated in patients with COPD and pulsus paradoxus, and left ventricular stroke volume is reduced during inspiration. Exaggerated variations in intrathoracic pressure alone did not explain pulsus paradoxus. Increased right ventricular filling and stroke volume during inspiration probably play a part.

Adult↗