Showing papers by "Cardiovascular Institute of the South published in 1982"

Ischaemia-induced negative U waves in electrocardiograms (an experimental study in canine hearts)

Abstract: To confirm the clinical impression that negative U waves are a sign of myocardial ischaemia, and to study their possible mechanism, we performed open chest experiments on dogs with the following results. (1) A negative U-wave tended to appear at the peripheral rather than the central portion of the cyanotic zone following coronary artery occlusion; (2) it also appeared temporarily at the central ischaemic area after release of coronary artery occlusion; (3) it became apparent or accentuated with augmentation of left ventricular performance at a postextrasystolic beat; and (4) it was eliminated by infusion of K+-free Tyrode solution, but appeared after an infusion of high K+-Tyrode solution into the regional coronary artery. These results indicate that negative U waves are a sign of myocardial ischaemia, which may be related not only to simple myocardial stretching but also to contraction and external high K+ in the ischaemic area.

Effectiveness of centrally acting drugs and diuretics in adolescent hypertension.

Abstract: The effectiveness and tolerance of a centrally acting antihypertensive agent (clonidine) was compared to that of a diuretic (hydrochlorothiazide) in treatment of adolescents with essential hypertension. After a phase on placebo 29 adolescents with fixed primary hypertension were randomly assigned, double blind, to one of two treatment groups. Active therapy was initiated at a low dose (0.1 mg clonidine b.i.d. or 24 mg hydrochlorothiazide b.i.d.) for 12 wk. In those in whom treatment goals for blood pressure control had not been reached, the dose was increased (clonidine to 0.2 mg and hydrochlorothiazide to 50 mg) for 12 wk. In the clonidine-treated group there was a reduction during low-dose therapy in systolic (P less than 0.05) and diastolic pressure (P less than 0.01) and heart rate (P less than 0.01). With low-dose diuretic therapy there was a reduction in systolic pressure only (P less than 0.05). Linear growth patterns were normal for both groups, but there was a reduction in serum potassium in the diuretic group (P less than 0.001). Of the two drugs investigated the centrally acting clonidine was more effective in blood pressure control (85%) than the diuretic (40%).

Dynamic and biochemical responses to single and repeated doses of clonidine during dynamic physical activity.

Abstract: Beta-adrenoceptor blockade increases serum K, which may be related to renin inhibition, hypoaldosteronism, and exercise-induced skeletal muscle release of serum K. We report on the dynamic and biochemical response to Clonidine (C) after single (S) 0.2-mg and repeated (R) 0.1-mg bid doses of C to six normal subjects at rest, 2 hr after dosing and immediately before dynamic physical activity (DPA) on a treadmill, and at peak activity and 2 hr after DPA. Blood pressure (BP), heart rate (HR), plasma renin concentration (PRC), aldosterone (ALD), serum K, epinephrine (E), and norepinephrine (NE) were measured in standing subjects before and 2 hr after placebo or C (S or R), at peak DPA, and 2 hr after exercise. K, BP, and HR were also determined during all stages of DPA. Results show a parallel rise in K at peak over rest after C (S or R) and after placebo. NE, E, and PRC decreased after 1 wk of C (P < 0.01), but the fall of ALD was only slight. The fall in NE at rest suggested a relationship to the decrease in systolic BP and rate pressure product after 1 wk on C. With DPA there is a normal yet smaller increase in systolic BP and also a smaller rise in HR with S- and R-dose C. There is no adverse rise in K in C-treated subjects during DPA. Clinical Pharmacology and Therapeutics (1982) 32, 18–24; doi:10.1038/clpt.1982.121

Intracoronary thrombolysis for acute myocardial infarction.

Abstract: Excerpt Recent observations have prompted reexamination of our concepts concerning optimal therapy for myocardial infarction. Rentrop and associates have shown the acutely occluded coronary artery ...

Echocardiographic diagnosis of an unusual anterior mediastinal mass.

Abstract: X-ray chest and CAT scan suggested an anterior mediastinal mass in a girl who had prominent left parasternal pulsations. M-mode and two dimensional echocardiography demonstrated an extracardiac fairly rigid cystic mass between right ventricle and chest wall, which proved to be a cystic chondroma arising from the fourth left costal cartilage.

Biochemical and dynamic responses to single and repeated doses of methyldopa and propranolol during dynamic physical activity

Abstract: Our purpose was to determine changes in potassium disposition with antirenin antihypertensives during dynamic physical activity in normal subjects receiving methyldopa and propranolol. Before the study, 2 hr after dosing and coincident with immediate preexercise on treadmill (at graded increases of exercise), and 2 hr after exercise, blood was sampled for determination of potassium, renin, aldosterone, and catecholamine levels. Blood pressure and heart rate were measured. The results demonstrate no greater increase in potassium after single or multiple doses of methyldopa than after placebo. After the first dose of propranolol there was a greater rise in potassium over that with placebo, but it was not observed after multiple doses, which may be related to the low doses. There were minor, but significant, changes in norepinephrine, renin, and systolic pressure with multiple-dose methyldopa and in renin, heart rate, and systolic and diastolic pressure with propranolol. Overall, the adrenergic responses to exercise with methyldopa and propranolol were biochemically altered rather than functionally impaired. The latter is related to dose and the underlying age and state of health of our subjects. Methyldopa (or Clonidine) may be useful in patients with hypertension who exercise and are predisposed to pertubations in potassium disposition. Clinical Pharmacology and Therapeutics (1982) 32, 701–710; doi:10.1038/clpt.1982.226

Potassium disposition and neuroendocrine effects of propranolol, methyldopa and clonidine during dynamic exercise.

Abstract: In order to determine the changes in potassium disposition with antirenin, antihypertensives during dynamic physical activity, a double-blind placebo controlled study was undertaken using normal volunteers receiving placebo or single and multiple dose clonidine, methyldopa and propranolol 0.2 mg. followed by 0.1 mg. bid x 7 days, 500 mg. followed by 250 mg. bid x 7 days or 80 mg. followed by 40 mg. bid x 7 days, respectively. Prior to study, 2 hours post dosing and coincident with immediate pre-exercise on treadmill, at graded increases of exercise and 2 hours post exercise (approximately 4 hours post dosing), blood was sampled for potassium, renin concentration, aldosterone and catecholamines. Blood pressure (BP) and heart rate (HR) were measured. The results demonstrate no greater increase in potassium over placebo with single or multiple dose clonidine or methyldopa. Following the initial dose of propranolol, 80 mg., there was a statistically greater rise in potassium over that seen with placebo but no...

Evaluation of the left ventricular function in aortic regurgitation by echocardiography and indicator dilution method.

Abstract: The left ventricular function and severity of LV volume overload were assessed in 30 patients with aortic regurgitation by a combined use of echocardiography and indicator dilution method.With decreasing functional capacity of patients, there tended to be greater increase in EDV, and decreases in CO, EF, Vcf, and BAP(DN)/ESV, and shift of LV function curve downward and to the right, reflecting LV myocardial dysfunction.There was a substantial correlation between functional capacity and the severity of regurgitation as well as LV myocardial function, suggesting the possibility that clinical symptoms may depend upon both the myocardial function and severity of aortic regurgitation. In contrast with many patients with AR of functional class I or II, who had relatively normal LV function, the patients of class III consistently showed substantial LV myocardial dysfunction.After sublingual administration of ISDN, BAP lowered, EDV and RF decreased. Lowering of BAP and RF were more prominent in class III than in class I.It has been proved that a combined use of echocardiography and indicator dilution method is of value in assessing the left ventricular function and regurgitant fraction in patients with aortic regurgitation, allowing a better understanding of the disease process and the potential for recognizing patients who may require early valve replacement.

Emergency Cardiac Care- Bootstrapping to 2,000 AD*

Abstract: The history of emergency cardiac care was outlined in the keynote address by James Warren during the 13th Bethesda Conference.’ The expertise gained in coronary care units was rapidly implemented in the emergency room and subsequently in the prehospital care of the patient with suspected coronary heart disease. Those advances have been facilitated by the availability of sophisticated communication systems and telemetry in addition to a manpower pool of trained professionals. Having come to this advanced stage, what shall we do next? Where is the need? We perceive a great need for further advances at both ends of the spectrum in the delivery of emergency care in the field and at the bedside in the hospital. As an extension of prehospital care, the bystander or witness is the potential instrument for the earliest possible delivery of life-saving health care. It is the bystander who must be educated in cardiopulmonary resuscitation (CPR). Such efforts are of proved value because they have significantly reduced morbidity and mortality in the victims of “sudden cardiac death.” 2m4 The education of so many bystanders, be they relatives or unrelated citizens, is an awesome but worthy task. It has the potential of saving 8 million lives over the next 2 decades. At the other end of the spectrum of care, we should focus on the preparedness of the physician to render life-saving cardiac care. In principle, all of the elaborate systems are intended to bring the patient to the hospital for definitive care. The 13th Bethesda Conference addressed the extraordinary resources that may be avail-