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Biomedical subjects

F G Dunn

Publications and source records attributed to F G Dunn.

At least 127 records · Page 7Linked to original sources
PubMed1980

Serial measurements of left ventricular dimensions by echocardiography. Assessment of week-to-week, inter- and intraobserver variability in normal subjects and patients with valvular heart disease.

The week-to-week, inter- and intraobserver variation in left ventricular echocardiographic measurements has been studied in 10 normal male volunteers and in five patients with stable valvular disease. A two-way analysis of variance showed no statistically significant variation either from week to week or between observers. Furthermore the within observer variation was minimal. Calculation of the coefficient of variation allowed confidence limits to be applied to each of the six ventricular measurements, thus providing ranges of variation in follow-up studies using M-mode echocardiography.

Aged↗
PubMed1979

Objective measurement of performance during acute stress in patients with essential hypertension: assessment of the effects of propranolol and metoprolol.

1. A standardized method of objectively measuring performance during simulated car driving is described. 2. The effect of a single dose of propranolol and metoprolol were compared with placebo in two groups of patients with untreated essential hypertension. 3. Performance was similar after beta-adrenoreceptor-blocking agents or placebo. 4. Blood pressure response to stress persisted after administration of the blocking agents.

Adult↗
PubMed1979

Natural biventricular hypertrophy in normotensive rats. I. Physical and hemodynamic characteristics.

The Wistar-Kyoto strain of normotensive rats (WKY) is being used as a control animal for studies involving the spontaneously hypertensive rats (SHR). A subset of the WKY demonstrating an inheritable transmission of biventricular cardiac hypertrophy (BVH) has been identified. The cardiac enlargement is pronounced, with right and left ventricular weights greater than twice normal in some animals. This natural development of BVH appears to be in response to an increased cardiac output. Blood pressure is normal and, therefore, peripheral resistance is reduced. Left ventricular injection of 15-micrometer radioactively labeled microspheres demonstrated that WKY with BVH had a substantial shunt fraction of their cardiac output (45 +/- 7% radioactivity recovered in the lungs vs. 3 +/- 2% in normal WKY). This subset of WKY with BVH provides a natural model of volume-load hypertrophy. In addition, investigators using the WKY for comparison with SHR should exclude animals with BVH.

Animals↗
PubMed1979

Antihypertensive and renal effects of tienilic acid.

Tienilic acid, a diuretic agent effective at the cortical diluting segment of the distal tubule, has been found to have equivalent antihypertensive action in a dose of 250 mg twice daily to hydrochlorothiazide in a dose of 50 mg twice daily. Tienilic acid reduced arterial pressure without diminishing renal plasma flow or endogenous creatinine clearance; moreover, it did so whilst achieving hypouricaemia through a uricosuric effect. Hypokalaemia was observed but corrected by supplemental potassium. A transient but reversible, slight elevation in serum creatinine concentration and significant hypertriglyceridaemia were also observed. In conclusion, tienilic acid seems to be a novel diuretic, well-suited for the patient with hypertension, particularly if there is coincidental gout or coexisting hyperuricaemia.

Glycolates↗
PubMed1978

Early treatment of myocardial infarction in the community.

The prehospital management of acute myocardial infarction by general practitioners and emergency-treatment service physicians was analysed in 53 patients. The correct clinical diagnosis was made or suggested before admission in 47 patients. Only 25 patients received analgesics from the general practitioner, and 32 were still in pain and needed diamorphine on admission to hospital. Only one patient received antiarrythmic treatment. The findings suggest that, despite accurate clinical diagnosis of acute myocardial infarction, deficiencies exist in the prehospital phase of management and that education programmes are worth consideration.

Analgesics↗
PubMed1978

Ticrynafen: a novel uricosuric antihypertensive natriuretic agent.

Interest in new diuretics with less side effects has led to the synthesis of ticrynafen, an uricosuric diuretic. This agent was compared with hydrochlorothiazide in a crossover design study involving 12 hypertensive men. Both agents significantly decreased mean arterial pressure from 8% to 18% in eight of the 12 patients. In addition to reducing body weight, these diuretics induced reversible changes in BUN and carbon dioxide content (increased) and plasma concentration of potassium and chloride ions (decreased). The most important change in renal function was a 2.5-fold increase in fractional urate clearance by ticrynafen associated with reduction of serum uric acid by 62%. Thus, ticrynafen is a promising therapeutic agent in hypertension, adding a unique uricosuric effect that should improve patient compliance.

Blood Pressure↗
PubMed1978

Benzothiadazine diuretics and death from myocardial infarction in hypertension.

1. Case records were examined of 66 patients who died while being treated for high blood pressure. 2. The possibility that benzothiadazine diuretics may have some deleterious as well as beneficial effects was investigated. 3. It is possible that the thiazides may have some adverse clinical effects, at least in females, with regard to the incidence of myocardial infarction in hypertensive patients.

Adult↗
PubMed1978

Relation between prognosis and the blood pressure before and during treatment of hypertensive patients.

1. A study was conducted amongst 1247 treated hypertensive patients to determine the predictive power of untreated baseline and achieved treated blood pressures in the development of the complications of hypertension. In addition the relative importance of systolic and diastolic pressures was calculated. 2. Statistical analysis was done by calculating univariate differences in blood pressure between cases with and without complications. The higher the univariate distance, the greater the predictive power. 3. Blood pressures achieved during treatment were more important than baseline pressures for predicting stroke in both men and women, confirming the benefits of antihypertensive therapy in preventing strokes. 4. There was some evidence of prevention of myocardial infarction in men and of angina in women as a result of therapy. 5. There was no evidence to suggest that any one group of drugs, including beta-adrenoreceptor-blocking drugs and thiazides, conferred any extra benefit in preventing coronary heart disease. 6. The systolic blood pressures achieved during treatment predicted stroke better than diastolic pressure, but no consistent trends were found for coronary heart disease.

Adolescent↗
PubMed1978

Standardized stress and hypertension: comparison of effect of propranolol and methyldopa.

1 Using a standardized form of mental stress, 21 patients with idiopathic hypertension were investigated before and after treatment with placebo (n=8), propranolol (n=7) or methyldopa (n=6). 2 Blood pressure was satisfactorily controlled in the propranolol and methyldopa groups but only the propranolol group showed modification of the pressor response to stress testing. 3 These results suggest that propranolol may provide more uniform control of blood pressure than methyldopa in patients with essential hypertension.

Adult↗
PubMed1978

Magnesium metabolism in patients with coronary heart disease.

1. The oral absorption of magnesium, its myocardial uptake and exchangeable magnesium have been studied in patients with coronary heart disease and controls using the radioactive isotope magnesium-28. 2. No significant difference in oral absorption or myocardial uptake was found between patients and controls. 3. The exchangeable magnesium per kg body weight was significantly lower in the patients than in the controls.

Adult↗
PubMed1978

Hemodynamic, reflexive, and metabolic alterations induced by acute and chronic timolol therapy in hypertensive man.

The hemodynamic, cardiovascular, and metabolic effects of acute (intravenous) and prolonged (four weeks oral) timolol treatment were assessed in 16 patients with mild or moderate essential hypertension. Fifteen patients completed the outpatient study and ten showed a fall in mean arterial pressure of at least 10 mm Hg. They also demonstrated a significant fall in supine systolic (7%), diastolic (9%), and mean arterial pressure. Hemodynamic evaluation was performed in 13 patients and cardiac index was found to be reduced with both intravenous (20%) and oral timolol (13%). There was no correlation between the decrease in cardiac index and arterial pressure. Calculated total peripheral resistance rose with intravenous timolol and returned toward, but not below, pretreatment values with the oral therapy. Left ventricular ejection rate also fell significantly with intravenous timolol but returned toward pretreatment levels with oral therapy. Plasma renin activity was reduced similarly with both modes of administration and its reduction also did not correlate with the fall in arterial pressure. Plasma volume fell in eight of 13 patients. Reflexive responses to the Valsalva maneuver were considerably modified by both intravenous and oral timolol but responses to 50 degrees upright tilt and handgrip were not. Timolol is an effective oral antihypertensive agent with similar hemodynamic and metabolic effects to propranolol.

Administration, Oral↗
PubMed1978

Hemodynamic correlates of saralasin-induced arterial pressure changes.

Angiotensin antagonists have proved useful in elucidating the clinical role of the renin-angiotensin system; and their diagnostic and therapeutic efficacy in hypertension has been the subject of many reports but the hemodynamic effects remain unknown. Therefore, saralasin was infused intravenously (1.3 mg/min for 30 min) in 26 sodium-depleted patients with hypertension. Systemic hemodynamic alterations were determined before, during, and after infusion. On the basis of mean arterial pressure (MAP) changes, patients were classified as responders, nonresponders, or pressorresponders (MAP changes greater than or equal to 10 mm Hg). MAP fall in responders was achieved through reduced cardiac output and/or total peripheral resistance, with minimal or absent reflexive heart rate increase. In nonresponders, despite no change in MAP, output fell in parallel with stroke index and left ventricular ejection rate, In pressorresponders, saralasin increased vascular resistance. Thus, in addition to variable effects on vascular receptors, saralasin produced inhibitory cardiac effects either through altered venous return or inhibition of contractility.

Adult↗
PubMed1978

ECG alterations with progressive left ventricular hypertrophy in spontaneous hypertension.

Although many ECG criteria exist for diagnosis of left ventricular hypertrophy (LVH) in hypertensive man, little is known of which specific ECG changes accompany progression of LVH with duration of hypertension. The spontaneously hypertensive rat (SHR) provides the best animal model thus far developed for studying this process since these animals demonstrate a progressive increase in left ventricular/body weight ratio with age. Electrocardiograms were performed under light ether anesthesia in four age groups of SHR and two normotensive Wistar strains (NR and WKY). Analysis of variance for two factors (rat strain and age) revealed progressively increased QRS and P-wave duration and delay in intrinsicoid deflection in SHR (p less than 0.001). Bipeak P-wave notching was also noted in SHR similar to left atrial abnormality in hypertensive man. Thus, specific ECG indices can be identified in association with the known progressive increase in left ventricular mass in SHR and should provide a better means to understand evolving ECG changes in LVH.

Age Factors↗
PubMed1977

Pathophysiologic assessment of hypertensive heart disease with echocardiography.

Assessment of the pathophysiologic changes associated with systemic hypertension has been limited by difficulty in justifying invasive studies of the left ventricle. Echocardiography, because it is notinvasive, offers an attractive method of assessing cardiac dimensions and function in hypertensive heart disease. Fourteen age-matched normotensive subjects and 31 patients with hypertension (but without clinical evidence of coronary artery disease) were studied before receiving any antihypertensive therapy. The patients with hypertension were classified into three groups on the basis of previously established electrocardiographic and chest X-ray criteria: group I, normal electrocardiogram and chest roentgenogram (13 patients); group II, left atrial abnormality by electrocardiogram and a normal chest roentgenogram (8 patients); and group III, left ventricular hypertrophy by electrocardiogram or chest roentgenogram, or both (10 patients). Mean arterial pressure increased significantly from group I to group II and from group II to group III (P is less than 0.01), and this increase was associated with a similar progressive increase in left ventricular mass assessed with echocardiogram (P is less than 0.01). A significant increase was also found in both posterior wall and septal thickness in groups II (P is less than 0.05) and III (P is less than 0.01). In association with this increased mass a significant decrease in ejection fraction and fractional fiber shortening was demonstrated in groups II (P is less than 0.05) and III (P is less than 0.01) although cardiac index was reduced only in group III (P is less than 0.05). Thus, increased ventricular mass can be identified with echocardiography at an early stage of hypertensive heart disease when only left atrial abnormality is identifiable with electrocardiographic criteria and decreased left ventricular performance occurs with increasing arterial pressure and left ventricular hypertrophy.

Adult↗
PubMed1977

Action of Nitroglycerin and amyl nitrite in labile and essential hypertension: hemodynamic differences.

Seventeen patients with labile hypertension received nitroglycerin and 18 received amyl nitrite. Twelve patients with established essential hypertension received nitroglycerin and 12 received amyl nitrite. Nitroglycerin reduced the systolic and mean arterial pressures and cardiac output in both groups, but had no effect on diastolic pressure and total peripheral resistance. Amyl nitrite decreased systolic, diastolic, and mean arterial pressures and peripheral vascular resistance and increased heart rate and cardiac output in labile hypertensives. In established hypertensive patients, amyl nitrite decreased systolic, diastolic, and mean arterial pressures and cardiac output, and had little effect on peripheral vascular resistance. Nitroglycerin reduced arterial pressure in labile and established hypertensives through venodilation and peripheral venous pooling. Amyl nitrite and effects similar to nitroglycerin in established hypertensives; in labile hypertensives it reduced arterial pressure through arterial dilation and a decrease in peripheral vascular resistance.

Adult↗