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Biomedical subjects

P Steele

Publications and source records attributed to P Steele.

At least 91 records · Page 5Linked to original sources
PubMed1977

Effect of parent coronary arterial occlusion on left ventricular function after aortocoronary bypass surgery.

In 62 men with open parent coronary arteries who underwent saphenous vein aortocoronary bypass to either the right or left anterior descending coronary artery, or both, left ventricular ejection fraction and wall motion of the anterior and inferior segments of the left ventricle were measured before and after (average 11 months) the operation. Of 34 left ventricular segments with open vein grafts and open parent coronary arteries, 91 percent were unaltered by the operation, none were in worse condition and 9 percent showed improved wall movement. Among 33 segments with open grafts but new total occlusion of the parent coronary arteries, 67 percent were unaltered, whereas the condition of 18 percent was worse and of 15 percent was improved. Among 21 segments with closed grafts but patent parent arteries, the condition of 29 percent was unchanged and of 71 percent was worse; among 14 segments with occlusion of both grafts and parent arteries the condition of 29 percent was unchanged and of 71 percent was worse. In 10 men with patency of all vein grafts and parent arteries, left ventricular ejection fraction was not altered (0.55 +/- 0.03 to 0.53 +/- 0.04 [average +/- standard error of the mean]) and in 11 with all grafts open but all parent arteries occluded left ventricular ejection fraction was unchanged (0.51 +/- 0.02 to 0.54 +/- 0.03). Left ventricular ejection fraction was decreased in eight men with occlusion of all vein grafts whether or not occlusion of the parent coronary arteries had occurred. The results suggest that occlusion of the parent coronary arteries in the presence of a patent vein graft does not unfavorably alter left ventricular ejection fraction or segmental wall motion, whereas graft occlusion is associated with deterioration of left ventricular ejection fraction and segmental motion whether or not the parent artery is also occluded.

Adult↗
PubMed1977

Platelet survival time in patients with hypoxemia and pulmonary hypertension.

Platelet survival time (autologous labeling with 51chromium) was measured in 63 patients in order to evaluate the role of platelets in the thromboembolic complications of patients with hypoxemia and pulmonary hypertension. Thirty-eight of these patients had chronic obstructive airways disease; 13, primary pulmonary hypertension; seven, recurrent pulmonary embolism; four, the Eisenmenger syndrome; and one, multiple pulmonary arteriovenous fistula. Forty-three patients were hypeakly associated with arterial oxygen tension ( r = 0.50), but not with the arterial carbon dioxide tension or the level of pulmonary artery pressure. Sulfinpyrazone lengthened platelet survival in 12 of 24 (50%) treated patients but this drug did not alter either arterial oxygen tension arterial carbon dioxide tension, or pulmonary artery pressure. Our results suggest that hypoxemia is associated with shortened platelet survival time and that platelets may, therefore, be involved in the thromboembolic complications that develop in patients with hypoxemia.

Blood Platelets↗
PubMed1977

Effects of digitalis on resting and isometric exercise myocardial perfusion in patients with coronary artery disease and left ventricular dysfunction.

Digitalis has been shown to improve the impaired ventricular function associated with coronary artery disease as well as to increase myocardial oxygen consumption and produce coronary vasoconstriction. To elucidate the net result of these contrasting effects, six patients with coronary artery disease and left ventricular ejection fractions less than 0.50 had 1.0 mCi thallium-201 injected intravenously at rest and during three minutes of 33% of maximal handgrip, off and on 0.25 mg daily maintenance digoxin. Thallium-201 scintigram images were taken 30 minutes later and were computer processed with orthogonal linearly interpolated background subtraction and maximal count density equalization. Processed images were visually graded on a 0, 1, or 2 scale for 18 sectors--nine from the AP projections and nine from the 40 degrees left anterior oblique projections. A score resulting from the summation of the 18 sector grades was made for each study, the maximum score being 36. Off digitalis, patients performing handgrip exercise decreased their scintigram scores from 25.7 +/- 1.5 (mean +/- SEM) to 23.0 +/- 1.0, P less than 0.05. When patients were on maintenance digoxin, scores did not change significantly during handgrip exercise. Post exercise scores were significantly higher on digoxin than off (P less than 0.05), whereas, resting scores were unaffected by digoxin. These data suggest that myocardial perfusion, as measured by thallium-201 uptake, is improved in patients on digitalis who have coronary artery disease and left ventricular dysfunction.

Blood Pressure↗
PubMed1976

Measurement of left ventricular mean circumferential fiber shortening velocity and systolic ejection rate by computerized radionuclide angiocardiography.

Recently attention has focused on ejection phase indexes as clinically relevant measures of left ventricular contractility. Using an Anger camera interfaced to a dedicated computer with injection of radionuclide (technetium 99m) into a wedged pulmonary arterial catheter we have developed a method for measuring left ventricular mean circumferential fiber shortening velocity and mean systolic ejection rate. For determination of mean fiber shortening velocity an area of interest coincident with the left ventricular minor axis is constructed and a time-activity curve obtained. In 31 atients radionuclide-determined values for mean fiber shortening velocity and mean systolic ejection rate correlated (r = 0.90, P less than 0.001 and r =0.98, P less than 0.001, respectively) with values for these indexes obtained from left cineventriculography. Left ventricular ejection fraction correlated with mean fiber shortening velocity and systolic ejection rate (r = 0.60, P less than 0.001 and r = 0.92, P less 0.001, respectively). No patient with a normal mean fiber shortening velocity or systolic ejection rate had a dimished ejection fraction. Because these radionuclide measurements do not require left heart catheterization, they can be frequently repeated.

Adult↗
PubMed1976

Correlation of platelet survival time with occlusion of saphenous vein aorto-coronary bypass grafts.

Platelet survival time is frequently shortened in patients with coronary artery disease, and it is one of several factors that might contribute to graft occlusion after saphenous vein coronary artery bypass (CAB). In 35 patients with CAB, average platelet survival (autologous labeling with 51Chromium) was shortened in 20 with one or more saphenous vein grafts occluded and normal in 15 with all grafts open. Of 15 with all grafts open, individual levels of platelet survival were normal in 10 while in 20 with one or more grafts occluded platelet survival was normal in only one. Platelet survival was not altered by coronary surgery and nine of ten with shortened platelet survival pre-operatively had graft occlusion. Platelet survival did not correlate with either parent artery occlusion or serum lipoproteins. These findings suggest a relationship between shortened platelet survival and saphenous vein graft occlusion and suggest that platelet suppressant therapy might be useful in preventing graft occlusion.

Adult↗
PubMed1976

Radionuclide angiocardiographic measurement of left ventricular volume and ejection fraction.

In recent years a number of different radionuclidic techniques have been developed to measure left ventricular volume and ejection fraction. Area-measurement concepts have been applied to static and electrocardiographically gated radionuclidic images which have resulted in accurate measurement of left ventricular end-diastolic volume (LVEDV) and ejection fraction (LVEF). Gated (end-diastolic and end-systolic) image analysis has also proven capable of detecting regional left ventricular wallmotion abnormalities in patients with coronary disease. Time-activity curves can be extracted from left ventricular images, and several dynamic techniques have been developed and have also resulted in accurate measurement of LVEDV and LVEF. Radionuclide methods are currently available which are accurate and atraumatic and consequently applicable to the serial study of patients with heart disease. In particular, several of these radionuclide methods are relatively inexpensive and should be able to be performed in most hospitals.

Angiocardiography↗
PubMed1976

Isosorbide dinitrate and intra-aortic balloon pumping in preinfarctional angina. Effects on central circulatory dynamics.

The dynamics of the central circulation were measured by a radionuclidic technique in 18 men with high-risk preinfarctional angina who received therapy with isosorbide dinitrate (n equals 18), intra-aortic balloon pumping (n equals 8), or both (n equals 8). Administration of 5 mg of isosorbide dinitrate sublinqually was associated with a reduction in stroke volume index (SVI), cardiac index (CI), systemic arterial blood pressure, and left ventricular end-diastolic volume (LVEDV) and with increased left ventricular ejection fraction (LVEF). Intra-aortic balloon pumping did not alter SVI or CI, but decreased systolic blood pressure and LVEDV and increased LVEF and diastolic blood pressure. The combination of therapy with isosorbide dinitrate and intraaortic balloon pumping resulted in decreased SVI, systolic blood pressure, and LVEDV and increased LVEF. Thus, therapy with isosorbide dinitrate reduced left ventricular preload, and intra-aortic balloon pumping reduced blood pressure, which resulted in a decreased LVEDV and an increase in LVEF. Therapy with isosorbide dinitrate and intra-aortic balloon pumping act to alter central circulatory dynamics in favor of reducing myocardial oxygen demand.

Adult↗
PubMed1976

Measurement of right and left ventricular ejection fractions by radionuclide angiocardiography in coronary artery disease.

Utilizing a dynamic radionuclide method, the right and left ventricular ejection fractions were measured in 96 men with arteriographically defined coronary arterial disease and in 14 normal subjects. The radionuclidically estimated right ventricular ejection fraction (RVEF) correlated with the RVEF measured with biplane cineventriculographic studies (r = 0.80; n = 43), and the left ventricular ejection fraction (LVEF) measured from radionuclide data have been shown to correlate with the LVEF from single-plane cineventriculographic studies (r = 0.89; n = 60). The mean normal RVEF was 0.57 +/- 0.01 (SE) (range, 0.51 to 0.64), and the mean normal LVEF was 0.66 +/- 0.01 (range, 0.57 to 0.74). The LVEF was decreased in the men with coronary arterial disease and isolated obstruction of the left anterior descending coronary artery, double-vessel disease, and triple-vessel disease, but was normal in those with isolated right coronary disease. The RVEF was normal in each of these groups, except those with triple-vessel disease. Myocardial infarction was associated with impairment of LVEF, although some patients without myocardial infarction had depressed LVEF. The RVEF was preserved in patients with infarction, except those with multiple myocardial infarctions. Thus, impaired LVEF in coronary arterial disease is associated with myocardial infarction, and RVEF is relatively preserved except in multiple-vessel disease and myocardial infarction and in association with impaired LVEF.

Adult↗
PubMed1976

Homograft and prosthetic aortic valve replacement: a comparative study.

Homograft aortic valve replacement was done in 103 patients and prosthetic aortic valve replacement in 106 between January 1962 and December 1973. Patients who received homograft and prosthetic valves were compared with respect to age, sex, preoperative functional impairment, infection, dyspnea, angina, hemodynamics, chest X-ray, electrocardiogram, associated operations, early and late mortality, and valve failure. Combined total mortality was 28% (12% operative, 8% first postoperative year, 8% late). Ten percent of valve required replacement. One year after operation, 70% of survivors were asymptomatic, 27% were improved, and 3% were unchanged or between homograft and prosthetic valve replacement. Valve-related failure and infections were more common after homograft aortic valve replacement. Emboli, hemorrhage, and hemolysis were commoner after prosthetic valve replacement. Fungal infections occurred in five homograft patients but in no patient with a prosthetic aortic valve. Severe properative symptoms or recent endocarditis was associated with greater mortality and valve failure in both the homograft and the prosthetic series. Increased mortality and failure was also seen in patients with either preoperative aortic regurgitation with high left ventricular end-diastolic pressure and low cardiac index, or aortic stenosis with cardiomegaly or roentgenographic evidence of congestive heart failure. Therefore, in two series of patients at equal risk, mortality and valve failure were similar for homograft and prosthetic aortic valve replacement.

Adolescent↗
PubMed1975

Increased platelet aggregability in young patients with stroke. Diagnosis and therapy.

Four patients ages 20 to 38 years had repeated cerebrovascular occlusions. Three of the four patients had vascular headaches (classical migraine in two) for some years before their first occlusive event occurred. When first seen at the time of their major cerebrovascular occlusion, all had evidence of plasma hyper-coagulability, and two of the women were receiving birth control pills. Many months later, while off the "pill" and on warfarin sodium (Coumadin) therapy, two women and one man continued to have new cerebrovascular symptoms. For the first time, their platelet aggregability was tested to several biological substances known to come in contact with platelets in vivo. At this time, all four patients were found to have platelet hyperaggregability. The three symptomatic patients also had a shortened platelet survival time. Long-term management of these patients with chronic platelet aggregability and chronic plasma hyper-coagulability is described.

Adult↗
PubMed1975

Left ventricular ejection fraction in severe chronic obstructive airways disease.

The subject of left ventricular involvement in chronic obstructive airways disease is controversial. We measured left ventricular ejection fraction (LVEF) in 120 patients with severe chronic obstructive airways disease, 92 of them acutely decompensated and 28 stable. A bedside radionuclide technic using a scintillation probe was used to measure LVEF. Of the 28 patients with acute respiratory failure, LVEF was normal (larger than or equal to 55 per cent) in 60 and subnormal in 32. Of the 28 patients with stable chronic obstructive airways disease, LVEF was normal in 12 and low in 16. Coronary artery disease could be demonstrated clinically or at autopsy in 13 of the patients with acute and in 7 of the patients with stable chronic obstructive airways disease. LVEF was 28 plus or minus 10.4 per cent (average plus or minus SEM) in the patients with acute chronic obstructive airways disease and coronary artery disease which was significantly different (P smaller than 0.001) from LVEF in patients without coronary artery disease (61 plus or minus 1.9 per cent). In the patients stable with chronic obstructive airways disease and coronary artery disease, LVEF was (42 plus or minus 3.5 per cent), significantly different (P smaller than 0.001) from LVEF in those without coronary artery disease (55 plus or minus 2.1 per cent). There was no relationship between LVEF and arterial oxygen, or carbon dioxide tension, or pH. Results suggest that LVEF is normal in patients with severe lung disease alone and that reduced LVEF in patients with chronic obstructive airways disease can reasonably be ascribed to coronary artery disease.

Acute Disease↗
PubMed1975

The square left ventricle: an angiographic and radionuclide sign of left ventricular thrombus.

The association of mural thrombus with left ventricular aneurysm is well documented, though angiographic documentation of left ventricular thrombus can be difficult. The authors describe the unique appearance of the left ventricular cavity in 5 patients. In all cases, ventriculograms obtained in the right anterior oblique position showed a squared apex. In 2 patients this phenomenon was also demonstrated by radionuclide angiocardiography. All 5 patients were found to have left ventricular thrombus at operation or autopsy.

Angiocardiography↗