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Biomedical subjects

J H Chesebro

Publications and source records attributed to J H Chesebro.

At least 199 records · Page 11Linked to original sources
PubMed1981

Platelet survival and the development of coronary artery disease in the young adult: effects of cigarette smoking, strong family history and medical therapy.

Cigarette smoking or a strong family history of coronary disease was present in 46 of 50 symptomatic patients with coronary artery disease who were younger than 50 years of age. We recorded a shortened platelet survival half-life (less than 92 hours) with 51Cr in 60% of these patients, in 56% of apparently normal persons of the same age who smoked or had a strong family history of coronary disease, and in only 14% of normal persons who did not smoke and had no family history (p less than 0.01). Lengthening of the shortened platelet survival toward normal occurred in coronary patients given dipyridamole plus aspirin and in apparently normal smokers who discontinued smoking (p less than 0.01). The study suggests a possible relationship among cigarette smoking, strong family history of coronary disease and platelet activation in the process of coronary atherogenesis in the young adult.

Adult↗
PubMed1981

Improvement of left ventricular exercise hemodynamic function after aorta-coronary artery bypass grafting.

In 39 patients with coronary artery disease and angina pectoris, exercise hemodynamic evaluation, left ventriculography, and coronary arteriography were performed both before and 3 to 36 months (mean 17 months) after aorta-coronary artery bypass grafting. Of the 32 patients with abnormal exercise hemodynamic responses before operation, 11 returned to normal at the postoperative study (Group N) and 21 remained abnormal (Group A). Preoperative characteristics (mean age, functional class, prior myocardial infarction, left ventriculographic appearance, mean ejection fraction, and mean number of vessels diseased) were similar in the two groups. Of the perioperative and postoperative characteristics examined (mean number of grafts, operative myocardial infarction, postoperative functional class, treadmill test result, and adequacy of left coronary artery revascularization), only the adequacy of left coronary artery revascularization differed between Groups N and A. Eight of 11 Group N and only three of 20 Group A patients had complete revascularization, with patent grafts, of the left coronary artery. We conclude that improved exercise hemodynamic function does occur in some patients after aorta-coronary artery bypass operations. Such improvement is most likely when all major lesions of the left coronary artery are completely revascularized.

Coronary Artery Bypass↗
PubMed1981

Antithrombotic therapy: role of platelet-inhibitor drugs. I. Current concepts of thrombogenesis: role of platelets. (first of three parts).

Definite evidence has confirmed that platelets play a major role in thrombus formation and embolization, especially in the arterial system. In addition, increasing evidence has now shown that platelet deposition and thrombus formation can contribute to the growth and progression of atherosclerotic plaques. For these reasons, considerable attention has been focused recently on the question of whether drugs that inhibit certain platelet functions can prevent or modify the course of arterial thromboembolic disease and atherosclerotic disease in humans. In this first part, we review the current understanding of the role of platelets in thrombus formation, especially in the arterial system. This section comprises (1) the phases of arterial thrombus formation and its ultrastructural and biochemical basis, (2) the clinicopathologic presentation and fate of the arterial thrombus, and (3) the role of laboratory tests in its detection.

Animals↗
PubMed1981

10. Antithrombotic therapy: role of platelet-inhibitor drugs. II. Pharmacologic effects of platelet-inhibitor drugs (second of three parts).

In this three-part series, the first part described the role of platelets in thrombogenesis, this second part considers the pharmacologic effects of platelet-inhibitor drugs, and the third part will discuss their clinical application. This second article comprises (1) the physiologic contribution of the vessel wall to the prevention of thrombosis, particularly the role of prostacyclin, (2) the mechanisms of action of platelet-inhibitor drugs in the prevention of thrombosis, (3) the ideal dose and ideal therapeutic combinations of conventional platelet-inhibitor drugs, (4) other agents and new agents that inhibit platelet function, and (5) drug side effects.

Aspirin↗
PubMed1981

Series on pharmacology in practice. 10. Antithrombotic therapy: role of platelet-inhibitor drugs. III. Management of arterial thromboembolic and atherosclerotic disease (third of three parts).

As already mentioned in the first two parts of this series, the evidence that platelets play an important role in arterial thromboembolic and atherosclerotic disease has led to numerous studies designed to test the possible efficacy of platelet-inhibiting drugs in various cardiovascular conditions in animals and in humans. Although the number of such published studies today probably exceeds 500, for practicality we comment only on those large prospective trials in humans that have followed the strict criteria of drug trials. We specifically refer to patients with valvular heart disease and prosthetic heart valves, patients with cerebrovascular disease, and patients with coronary artery disease.

Anticoagulants↗
PubMed1981

A prospective study of peripheral occlusive arterial disease in diabetes. II. Vascular laboratory assessment.

Noninvasive tests of the peripheral circulation were used to quantify the presence and severity of occlusive arterial disease in the lower extremities in 707 subjects on entry into a prospective study. Four groups were studies: 124 normal subjects, 157 patients with clinically evident occlusive arterial disease, 295 patients with diabetes mellitus without clinically evident occlusive arterial disease, and 131 patients with diabetes mellitus and clinically evident occlusive arterial disease. The lower extremity-to-arm systolic blood pressure ratios at rest, ankle-to-arm systolic blood pressure ratios after exercise, and segmental plethysmographic recordings accurately identified the groups with occlusive arterial disease and quantified the spectrum of severity in each of the groups. The 1-minute postexercise ankle-to-arm systolic blood pressure ratio was the single best indicator in discriminating between normal subjects and patients with occlusive arterial disease. The exercise electrocardiogram was positive in 30 of the 583 patients and in none of the group of normal subjects. The systolic blood pressure was falsely elevated as a result of sclerotic, noncompressible arteries in the segment of the limb under the pneumatic cuffs in 12 of the patients but in none of the normal subjects.

Aged↗
PubMed1979

Noninvasive radioisotopic technique for detection of platelet deposition in coronary artery bypass grafts in dogs and its reduction with platelet inhibitors.

At 8 and 32 hours after saphenous vein bypass graft surgery in six dogs, in vivo images of the graft were obtained with a gamma camera after intravenous injection, 2 hours postoperatively of autologous platelets labeled with indium-111. Platelet deposition in the grafts could be imaged in vivo from the scintiphotos. In vitro images of the excised heart showed saphenous vein graft uptake confirming the in vivo image. In vitro determination of radioactivity in the graft averaged 17 +/- 14 times greater than in blood and 33 +/- 26 times greater than in the lung. Under identical conditions, in eight dogs treated with dipyridamole (55 mg/day) plus aspirin (325 mg/day), the grafts appeared to have considerably less platelet deposition as estimated by imaging. In vitro determination of radioactivity in the graft averaged 5 +/- 2 times greater than in blood and 8 +/- 4 times greater than in the lung (p less than 0.01). This noninvasive technique may be a promising tool for a better understanding of the role played by platelets in the process of occlusion of saphenous vein bypass grafts in man and its prevention with platelet inhibotors.

Animals↗
PubMed1978

Regional myocardial wall thickening response to nitroglycerin. A predictor of myocardial response to aortocoronary bypass surgery.

The peak rate of systolic wall thickening (p +/- dTw/dt) in regions of the left ventricle (LV) was determined preoperatively by biplane roentgen videometry in 18 patients before and after sublingual administration of nitroglycerin (NTG) and 3-23 months (median 12) after aortocoronary bypass surgery. The regional LV response to NTG was a reliable predictor for postoperative improvement in regional wall dynamics after successful aortocoronary bypass grafting. The ejection fraction response to NTG or surgery will not predict the regional myocardial response to NTG or surgery, nor will the regional response predict the global response. Subendocardial myocardial infarction is another cause of unimproved regional myocardial function after NTG and aortocoronary bypass surgery.

Adult↗
PubMed1978

Relation between left coronary artery stenosis and regional left ventricular function.

The effect of stenosis of the left main and proximal anterior descending coronary arteries on anterior left ventricular wall dynamics was investigated in 70 patients with ischemic heart disease by the use of roentgen videometric analysis of left ventricular angiograms. In all patients with ischemic heart disease, mean values for peak rate of systolic wall thickening and diastolic wall thinning were significantly smaller than normal (P less than 0.01). In patients without infarction, there was no correlation between peak rate of systolic anterior wall thickening and stenosis of the coronary artery supplying it, but there was a significant reduction in peak rate of diastolic wall thinning (P less than 0.01) in patients with stenosis greater than 90%; this difference was not apparent at any lower degree of stenosis. This population could not be recognized by any other parameter of global or regional ventricular function; thus, diastole is more sensitive to regional left ventricular dysfunction than systole.

Adult↗
PubMed1977

Complete occlusion of the left main coronary artery and the importance of coronary collateral circulation.

Study of four patients who survived complete occlusion of the left main coronary artery forms the basis of conclusions concerning the functional significance of coronary collateral circulation. Each of these patients had prominent collateral circulation from the right coronary artery. Global left ventricular function was maintained to the extent that congestive heart failure did not occur; the biplane ejection fraction was normal in the two patients where measurement was possible. The peak rate of systolic wall thickening by roentgen videometry in anterior left ventricular segments was normal in one patient and mild to moderately depressed in another. Experience with the patients described herein indicates that coronary collateral flow can provide critically needed circulatory support for the patient with coronary artery disease.

Collateral Circulation↗
PubMed1976

Videometric analysis of regional left ventricular function before and after aortocoronary artery bypass surgery: correlation of peak rate of myocardial wall thickening with late postoperative graft flows.

The peak rate of systolic wall thickening (pdTw/dt) in regions of the left ventricle was determined by biplane roentgen videometry in 60 patients before and a median of 14 mo after aorto-coronary bypass graft surgery. The left ventricular ejection fraction, stroke volume, and end-diastolic volume and pressure did not change significantly after surgery in the presence of patent or occluded grafts (P greater than 0.05). Statistically significant increases occurred in the peak rate of systolic wall thickening regions supplied by patent bypass grafts, and significant decreases occurred in regions with occluded grafts (P less than 0.01). Of 42 preoperatively hypokinetic regions (pdTw/dt greater than 0 less than 5.0 cm/s) supplied by a patent graft, 30 improved by an average of 2.6 cm/s after operation; 18 returned to normal. Failure of 24 hypokinetic regions to improve to normal was associated with myocardial infarction in 11 or with late postoperative graft blood flows of less than 60 ml/min measured by videodensitometry, in 10. All seven preoperatively akinetic (pdTw/dt=0) or dyskinetic (pdTw/dt less than 0) regions did not improve after the operation despite the fact that, in five of the seven, coronary bypass flows were over 60 ml/min. All eight preoperatively hypokinetic regions supplied by coronary artery graft flows of less than or equal 40 ml/min failed to improve to normal after operation. All nine preoperatively hypokinetic regions supplied by coronary artery graft flows of over 60 ml/min improved to normal after surgery. Late postoperative coronary artery bypass graft flows, the functional status of the myocardium, the status and distribution of the native coronary circulation, and decreased regional function elsewhere in the ventricle must all be considered when regional left ventricular function is interpreted.

Adult↗
PubMedDate not supplied

Influence of arterial damage and wall shear rate on platelet deposition. Ex vivo study in a swine model.

To study the influence of blood flow on platelet interaction with selected biological surfaces, we have developed an ex vivo perfusion chamber system. In the present experiments, deendothelialized pig aorta and collagen Type I bundles from Achilles tendon were exposed to either native or heparinized pig blood for periods of time ranging from 1 to 30 minutes, and for flow rates corresponding to wall shear rates of 106 to 3380 sec-1. On the deendothelialized vessel wall, platelet deposition increased with both exposure time and wall shear rate, reaching a maximum value between 5 and 10 minutes of perfusion. At high shear rates and long exposure time (over 10 minutes), platelet deposition decreased from maximum values, indicating that some platelets were embolized by the flow. Ultrastructure analysis of the specimens showed platelet activation, spreading, and degranulation. Collagen induced a progressive accumulation of platelets following a power type curve of aggregate growth with exposure time without reaching a saturation level, even after long perfusion times (30 minutes) and high wall shear rates (3380 sec-1). In conclusion, the reactivity of the exposed materials and the local shear rate, defined by the blood flow and the patent luminal cross section, regulate platelet deposition to injured vascular wall.

Animals↗