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Biomedical subjects

M Hartford

Publications and source records attributed to M Hartford.

At least 91 records · Page 5Linked to original sources
PubMed1988

Dyspnoea of cardiac origin in 67 year old men: (1). Relation to systolic left ventricular function and wall stress. The study of men born in 1913.

The relation between dyspnoea of presumed cardiac origin and disturbed left ventricular systolic function was studied in a group of 67 year old men from the general population of Gothenburg, Sweden. Forty two men with cardiac dyspnoea were identified and 45 controls were randomly selected from a screened cohort of 644 men. Dyspnoea was graded according to the World Health Organisation standard, and M mode echocardiography, carotid pulse tracing, an apex cardiogram, and phonocardiography were used to evaluate the grade of dyspnoea and its relation to systolic time intervals, left ventricular ejection indices, and wall stress. The dyspnoea grade was significantly related to the left ventricular end systolic dimension, to septal and posterior wall fractional thickening, and to ejection indices such as fractional shortening. The dyspnoea grade was also significantly correlated with the ratio of end systolic wall stress to end systolic volume index. There was a close relation between end systolic wall stress and mean velocity of circumferential fibre shortening adjusted for heart rate. This relation did not clearly show reduced inotropy in the dyspnoeic men. There was no relation between the degree of dyspnoea and the systolic time intervals. Among the systolic variables obtained by echocardiography the only abnormal finding in mild to moderate dyspnoea was an increased end systolic dimension. The grade of cardiac dyspnoea seemed to be related to the degree of systolic left ventricular dysfunction, which was considerably impaired in severe dyspnoea. In population studies left ventricular end systolic dimension and fractional shortening may provide sufficient information on systolic function without the need to assess variables that are independent of load.

Aged↗
PubMed1988

Dyspnoea of cardiac origin in 67 year old men: (2). Relation to diastolic left ventricular function and mass. The study of men born in 1913.

The relation of cardiac dyspnoea to diastolic left ventricular dysfunction was examined in a sample of 67 year old men from the general population of Gothenburg, Sweden. Forty two men with cardiac dyspnoea and 45 controls were selected from the screened cohort of 644 men. M mode echocardiography, apexcardiography, and phonocardiography were used to evaluate heart sounds, diastolic time intervals, aortic root motion (atrial emptying index); peak rate of change in left ventricular dimension, left atrial and ventricular size; and left ventricular mass. There was a significant relation between dyspnoea grade and left ventricular mass and posterior wall thickness. Dyspnoea grade also correlated significantly with the amplitude of the rapid filling wave and the third heart sound, atrial emptying index and left atrial size, the pulmonary component of the second heart sound, and the dimension of the right ventricle. In mild to moderate dyspnoea fractional shortening was normal, but posterior wall thickness and left atrial dimension were increased. The time from the second heart sound to the O point of the apexcardiogram, adjusted for heart rate, was significantly prolonged in mild to moderate dyspnoea, but not in severe dyspnoea. There was a significant decrease of rate adjusted isovolumic relaxation time, probably secondary to altered loading conditions, in severe dyspnoea, but not in mild to moderate dyspnoea. When the effect of systolic function was excluded multivariate analyses showed that the relation between dyspnoea grade and left atrial dimension persisted. The finding that diastolic abnormalities of the heart contributed to the generation of cardiac dyspnoea may have implications for treatment.

Aged↗
PubMed1988

Renal function before and after withdrawal of long term antihypertensive treatment in primary hypertension.

Glomerular filtration rate (GFR) and renal plasma flow (inulin and para-aminohippurate clearance) were measured in a random sample of 17 normotensive and 20 untreated patients with primary hypertension. At the 7-year follow-up, 19 patients were on metoprolol (as the sole drug or in combination with either hydrochlorothiazide or hydralazine) and 1 patient was on hydrochlorothiazide. They were re-examined after withdrawal of treatment and return of hypertension. At the 7-year follow-up GFR was more reduced in the hypertensive (-17%) than in the normotensive group (-9%). The percentage decrease in renal blood flow was the same in both groups. No significant renal function changes appeared after withdrawal of treatment. In conclusion, there was a slightly greater deterioration in GFR in the hypertensive patients after long term treatment with metoprolol than can be explained by normal ageing.

Antihypertensive Agents↗
PubMed1987

The relationship between obesity-related metabolic factors and vascular changes in early hypertension.

The relationships of obesity, glucose metabolism and hormonal variables to mean arterial pressure (MAP) regional vascular resistance and signs of structural vascular changes, were determined in 70 men aged 49 years with normal to mildly elevated MAP randomly selected from a population sample. Regional vascular resistances and signs of structural vascular changes were measured in the calf by plethysmography at rest and during maximal dilatation, and in the kidneys by renal blood flow determination during graded subpressor doses of angiotensin II. MAP was positively correlated to body fat, waist circumference, fat cell size, and to blood glucose 60 minutes after an oral load. This supports an association between central obesity, impairment of glucose tolerance and hypertension. MAP was, however, unrelated to sodium intake, blood volume and indices of sympathetic nervous activity and the renin-angiotensin system. Resting vascular resistance in the calf was unrelated to MAP, while renal vascular resistance rose significantly with increasing MAP. Signs of structural change were significantly correlated to MAP in both these vascular areas. These signs were also associated with central obesity of the hypertrophic type and with impairment of glucose tolerance, even when the association to MAP was accounted for. These factors may be involved in the pathogenesis of the structural adaptation of resistance vessels as hypertension develops.

Blood Glucose↗
PubMed1984

Göteborg Metoprolol Trial: clinical observations.

Heart rate, systolic blood pressure and rate-pressure product were analyzed during the first 18 hours and 4 days after intravenous metoprolol or placebo. On injection of metoprolol there was an immediate decrease in mean heart rate from 72.9 +/- 0.6 to 62.7 +/- 0.4 beats/min, but no change was found in the placebo group. The difference in heart rate remained during the first 4 days. Systolic blood pressure was reduced from 144.1 +/- 0.9 to 134.6 +/- 0.9 mm Hg after intravenous metoprolol and was lower than that in the placebo group during 4 days of follow-up. Indirect signs of congestive heart failure tended to be less severe in patients given metoprolol within 12 hours of the onset of symptoms than in those given placebo. The duration of hospitalization also tended to be shorter in patients given early metoprolol treatment than in those given placebo early.

Blood Pressure↗
PubMed1983

The relation between cardiac hypertrophy and hypertension.

Left ventricular mass determined echocardiographically was related to blood pressure in a stratified random sample (n = 120) of 49-year-old men selected from a blood pressure screening and covering a wide range of blood pressures. Only subjects not on antihypertensive treatment were studied. Left ventricular mass was also related to sympathetic activity, the renin-angiotensin-aldosterone system and glucose metabolism. A poor correlation between left ventricular mass and blood pressure was found in the entire study group. In the upper blood pressure range only blood pressure during isometric exercise was significantly correlated with left ventricular mass. In this range there were significant correlations between left ventricular mass and 24 hour urinary noradrenaline excretion and plasma aldosterone. In the intermediate blood pressure range there was an association between left ventricular mass and blood glucose and plasma insulin. It is concluded that in mild to moderate hypertension other factors probably modify the hypertrophic response to rising arterial pressure.

Aldosterone↗
PubMed1983

Left ventricular mass in middle-aged men. Relationship to blood pressure, sympathetic nervous activity, hormonal and metabolic factors.

Left ventricular (LV) mass was studied echocardiographically in 120 middle-aged men representing a wide range of blood pressures (BP) and its relation to the following factors was analysed: BP measured in different resting situations and during isometric exercise, 24 hour urinary noradrenaline excretion and plasma noradrenaline, plasma renin activity, plasma angiotensin II, plasma aldosterone, blood glucose and plasma insulin. Each BP measurement showed weak but significant correlation with LV mass in the entire study group. In the upper BP range only BP measured during isometric exercise was correlated with LV mass. In the upper BP range there were also significant correlations between both the 24 hour urinary noradrenaline excretion and plasma aldosterone and LV mass, while blood glucose and plasma insulin were significantly correlated with LV mass in the intermediate BP range. Thus there was a surprisingly low correlation between LV mass and arterial BP. The findings regarding sympathetic nervous activity, hormonal and metabolic factors might indicate that these factors are involved in the pathogenesis of an increased LV mass in some individuals with essential hypertension.

Angiotensin II↗
PubMed1982

Blood pressure in relation to the renin-angiotensin-aldosterone system.

The relationship between blood pressure (BP) and the renin-angiotensin-aldosterone system was studied in a stratified random sample (n=120) of 49-year-old men selected from a BP screening and covering a wide range of BPs. Only subjects not on antihypertensive treatment were included. None had malignant or secondary hypertension. Plasma renin activity, plasma concentrations of angiotensin II, aldosterone, sodium, potassium and noradrenaline and the 24-hour urinary excretions of sodium, cortisol and noradrenaline were determined. Of these variables, only p-aldosterone was significantly correlated wtih BP, both in the whole study group (R=0.22, p less than 0.02, n=119) and in the subjects with the highest BP range (R=0.36, p less than 0.02, n=30). Of the clinical groups compared, the hypertensive subjects had significantly higher mean p-aldosterone than the borderline and normotensive subjects. Multiple regression analysis showed that the 24-hour urinary excretion of noradrenaline was the factor most strongly correlated to p-aldosterone, suggesting that the sympathetic nervous system might stimulate aldosterone secretion. Our findings indicate that aldosterone may be of importance for the development and maintenance of essential hypertension.

Aldosterone↗
PubMed1981

Blood pressure and the renin--angiotensin--aldosterone system.

1. The relationships between blood pressure and the components of the renin--angiotensin--aldosterone system were studied in 49-year-old men (n = 120) who were selected at random from the total population so as to be representative of all blood pressure levels. 2. Only plasma aldosterone concentration was significantly correlated with blood pressure, both in the whole study group (r = 0.22; P less than 0.02) and in the hypertensive blood pressure range (r = 0.36; P less than 0.02). The hypertensive subjects had a significantly higher plasma aldosterone concentration than the borderline and normotensive subjects. 3. Multiple regression analysis including factors related to the renin--angiotensin--aldosterone system, showed that the 24 h urinary excretion of noradrenaline was the factor most strongly correlated to plasma aldosterone. 4. The findings indicate that aldosterone may be the most important component of the renin--angiotensin--aldosterone system in the development and maintenance of essential hypertension.

Aldosterone↗
PubMed1980

Blood pressure and renal function.

The relationship between blood pressure (BP) and renal function was studied in samples of 49-year-old men. Of 3 205 49-year-old men, 2 376 (74%) took part in a BP screening. By systematic sampling, based on diastolic BP levels varying from very low to very high, 120 subjects were selected for this study. Only subjects who were not on antihypertensive treatment were included. Renal blood flow (RBF), renovascular resistance (RVR), glomerular filtration rate (GFR), filtration fraction (FF) and renal concentrating capacity were studied in 111 subjects, none of whom had advanced hypertension. With increasing BP there was a decrease in RBF (r = -0.34) and an increase in RVR (r = 0.81) and FF (r = 0.35). The changes in renal haemodynamics occurred gradually from low to high BP, and did not start at any particular BP level. With increasing BP, GFR was unchanged. An "autoregulation of GFR" was thus found at all BP levels studied. Renal concentrating capacity was unchanged. These findings indicate that renal haemodynamics in essential hypertension are adjusted mainly to ensure a constant GFR.

Blood Pressure↗
PubMed1979

Heart and kidney involvement and prognosis in hypertension. A study concerning referred hypertensive patients and hypertensive patients found by blood pressure screening.

Severity of hypertension, frequency of secondary hypertension and prognosis have been compared in two groups of hypertensive men. The first group (n=686) was taken from a blood pressure screening of a total population sample. The other group (n=154) consisted of hypertensive men, referred to a hypertension clinic by physicians. The mean age of the groups was the same, (X=52 years, range 46--59 years). All went through the same investigations and were followed up and treated in a similar way at the hypertension clinic. The referred men had more severe hypertension, as shown by significantly more heart and kidney involvements. They also had a higher incidence of myocardial infarction, implying a poorer prognosis with regard to cardiovascular disease. The analysis shows the importance of a detailed description of studied groups, not only in terms of blood pressure, age and sex, but also with respect to the frequency and degree of present and previous signs of heart and kidney involvement. With such a description it is possible to compare results from different studies regarding pathophysiological mechanisms and the effect of treatment in hypertension.

Cerebrovascular Disorders↗
PubMed1977

Sodium excretion and sympathetic activity in relation to severity of hypertension.

The relationship between the severity of hypertensive disease and sodium excretion and sympathetic activity has been studied in normotensive (n = 19) and hypertensive (n = 19) men of the same derived from screening a total population. Sympathetic activity was determined from noradrenaline excretion and the severity of hypertension was assessed by measuring resting diastolic BP, left ventricular hypertrophy on orthogonal ECG and the glomerular filtration rate. In the hypertensive group the resting BP correlated well both with signs of left ventricular hypertrophy, i.e. with the degree of severity of the hypertensive disease. Up to the level of 90 mm Hg resting diastolic BP, sodium excretion rose in agreement with theory of pressure diuresis. Above 90 mm Hg, however, both sodium and noradrenaline excretion fell with increasing BP. This indicated that in more advanced hypertension the sodium balance overrides the sympathetic activity in the long-term relation of BP. In another series of 49-year-old-men noradrenaline excretion fell with increasing renal vascular resistance indicating that the increase in the latter variable could not be explained by increased sympathetic tone. On the basis of the results a hypothesis on the sequence of events leading to development of hypertension, is presented.

Blood Pressure↗