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Biomedical subjects

J Wikstrand

Publications and source records attributed to J Wikstrand.

At least 163 records · Page 9Linked to original sources
PubMed1978

Coronary heart-disease after treatment of hypertension.

Within a group of 1026 men aged 47-54, cause-specific death-rates and the incidence of non-fatal myocardial infarction and stroke in treatment group of 635 hypertensive men (casual systolic B.P. greater than 175 or diastolic B.P. greater than 115 mm Hg on two occasions) treated at a hypertension clinic were compared with those in a control group of 391 men (causal systolic B.P. greater than 175 or diastolic greater than 115 mm Hg on only one occasion) who remained mainly untreated during their 4.3 years of follow-up. The predicted risk of coronary heart-disease (C.H.D.) at entry, calculated by a multiple logistic function, was slightly higher in the treatment group. Total death-rate during follow-up was significantly lower in the treatment group (3.3%) than in the control group (6.1%). The difference in death-rate for C.H.D. was of the same relative order (0.8% versus 1.5%), as was the incidence of non-fatal myocardial infarction (2.8% versus 5.4%), although none of the differences reached statistical significance. However, the pooled incidence of fatal and non-fatal C.H.D. was significantly lower in the treatment group (3.6%) than in the control group (6.9%). The results suggest that antihypertensive treatment might be effective in preventing or postponing C.H.D. in middle-aged men.

Cerebrovascular Disorders↗
PubMed1977

Distortion of non-invasive cardiac pulse curves. A capillary-damped pick-up and a calibration unit forapex cardiograms and other pulse curves.

A calibration unit and a capillary-damped pick-up, of funnel type, intended for apex cardiograms and other non-invasive cardiac pulse curves are presented. The physical properties of a recording system, suitable for non-invasive cardiac diagnostic techniques, are reviewed. In 4 identical recording units consisting of a funnel with and without capillary damping, connected via air transmission to a transducer, the overamplification in the underdamped systems varied between 2-4 and 4-3, and in the capillary-damped systems between 1-1 and 1-2. The capillary damping gave an approximately linear relation between phase shift and frequency in the high frequency range with a calculated delay of about 4ms. The low frequency time constant in the systems varied between 1-9 and 4-6 s, depending on the amplifier setting used, which for sine curves of frequency 0-5 and 2 Hz means an apparent prematurity for their maxima and minima varying between 53 and 1 ms, this being larger with lower frequency time constants and lower frequency curves.

Amplifiers, Electronic↗
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↗
PubMed1976

Sodium excretion and sympathetic activity in relation to severity of hypertensive disease.

The relationship between the severity of hypertensive disease and sodium excretion and sympathetic activity has been studied in subjects of the same age and sex derived from screening a total population. 19 untreated subjects with casual blood-pressure (B.P.) above 175/115 mm Hg on two separate occasions made up the hypertensive group. A normotensive group (n =19) was obtained by selecting a 5% random sample from all subjects with casual B.P. below 160/95. Sympathetic activity was determined from noradrenaline excretion and the severity of hypertension assessed by recording resting diastolic B.P., signs of left ventricular hypertrophy on orthogonal E.C.G., and the glomerular filtration-rate. In the hypertensive group the resting B.P. correlated well both with signs of left ventricular hypertrophy and with the glomerular filtration-rate--i.e., the degree of severity of the hypertension. Up to the level of 90 mm Hg resting diastolic B.P., sodium excretion rose in complete agreement with the theory of pressure diuresis. Above 90 mm Hg, however, sodium and noradrenaline excretion fell with increase of B.P. These two findings indicated that with increasing severity of hypertension the sodium balance overrides the sympathetic activity in the long-term regulation of B.P. This may have both prognostic and therapeutic implications.

Adrenal Medulla↗
PubMed1976

Plasma renin activity and hypertensive organ manifestations in 50-year-old males.

From a screening examination in a randomly selected third of the 50-year-old male population in Göteborg, Sweden, a 10% subsample was selected as a reference group (n=80). All untreated persons with SBP greater than 175 or DBP greater than 115 mmHg on two separate occasions made up the hypertension group (n=35). The reference group and the hypertension group were subjected to the same investigations, including BP measurement before and after rest and determination of plasma renin activity (PRA), urinary sodium and norepinephrine excretion and GFR. Plasma renin activity was approximately normally distributed in both the reference and the hypertension group. Mean values were 0.78 +/- 0.18 and 0.65 +/- 0.17 ng/ml/h respectively, the difference being almost statistically significant (0.10 greater than p greater than 0.05). There was no difference with respect to sodium excretion between the reference group and the hypertension group. In the reference group, heart rate was positively correlated to PRA and to urinary norepinephrine excretion during the day. No linear correlation between PAR and BP was found, either in the reference group, or in the hypertension group. Sodium excretion during the day was positively correlated to GFR in the hypertension group, but not in the reference group. Compared to hypertensives with normal or high sodium excretion during the day, the hypertensives with low sodium excretion during the day were characterized by a higher BP, a lower GFR and a reversed diurnal rhythm of urine excretion. Thus, low sodium excretion seemed to indicate more severe hypertension with increased renal resistance during the day. The hypertension group was also divided with regard to sodium excretion into a low, normal and high renin group. The low renin group had the lowest GFR and with rising renin group (from low via normal to high) there was a significant increase in GFR and a significant decrease in resting BP. The results indicate that low renin hypertension is not a more mild, but indeed rather a more severe form of hypertension.

Blood Pressure↗
PubMed1976

Non-invasive assessment of the heart in the hypertensive.

The prevalence of signs of heart involvement was studied non-invasively with orthogonal and conventional ECG, apexcardiogram, carotid pulse tracing and phonocardiogram in a group of untreated hypertensives (n = 35) and a reference group (n = 73). All were derived by screening a random population sample of 50-year-old men.

Animals↗
PubMed1976

Orthogonal electrocardiogram, apex cardiogram, and atrial sound in normotensive and hypertensive 50-year-old men.

The prevalence of signs of heart involvement was studied non-invasively in a group of untreated hypertensives (n=35) and a reference group (n=73), all derived from a random population sample of 50-year-old men. Signs of left ventricular hypertrophy were studied by means of orthogonal electrocardiography and conventional electrocardiography. Signs of decreased distensibility of the left ventricle were studied by apex cardiography and registration of atrial sounds. Left ventricular hypertrophy among hypertensives was significantly more common according to orthogonal electrocardiography (33%) than according to conventional electrocardiography (9%), indicating that the former may be a better method for detection of left ventricular hypertrophy than the latter. In the hypertension group the amplitude of the R wave in lead X on orthogonal electrocardiography was positively correlated to casual diastolic blood pressure (r=0-40) and to diastolic blood pressure after one hour's rest (r=0-65). The degree of pressure load leading to left ventricular hypertrophy seems to be better reflected by resting than by casual blood pressure. There was no hypertensive subject with both signs of left ventricular hypertrophy on orthogonal electrocardiography and either an a/H ratio over 15 per cent or an abnormal atrial sound, indicating two different forms of cardiac involvement as the result of hypertension. Casual blood pressures became normal during rest in hypertensives with a/H ratio over 15 per cent on apex cardiography or abnormal atrial sound, not in hypertensives with signs of left ventricular hypertrophy on orthogonal electrocardiography.

Blood Pressure↗
PubMedDate not supplied

Initial therapy for mild hypertension.

The treatment of mild hypertension has been a subject of controversy because its benefits versus risks are not as well established as they are for moderate to severe hypertension. Results of several studies, however, now show that treatment reduces the frequency of stroke in those with milder blood pressure elevations. New guidelines published by the Joint National Committee recommend that treatment of mild hypertension begin with either a diuretic or a beta blocker. The effect on the most common complication of mild hypertension, that is, coronary heart disease (myocardial infarction and sudden cardiac death), has, however, not been encouraging in studies in which diuretics have been used as first-line treatment. Two large-scale primary preventive studies compared the efficacy of diuretics and beta blockers in reducing coronary heart disease in hypertensive patients; results were in favor of beta blocker regimens in men. So far there is some evidence, but no hard scientific proof, that certain beta blockers offer advantages over diuretics in preventing myocardial infarction and sudden cardiac death in hypertensive patients. A major concern with the use of diuretics is the risk of hypokalemia; this can be reduced when they are combined with beta blockers.

Adrenergic beta-Antagonists↗
PubMedDate not supplied

Femoral artery wall morphology, hemostatic factors and intermittent claudication: ultrasound study in men at high and low risk for atherosclerotic disease.

The aim of this study was to examine whether there was a relationship between ultrasound-assessed morphology of the femoral artery wall and hemostatic factors, and whether these factors were associated with intermittent claudication. One hundred and thirty men at high cardiovascular risk and 51 men at low risk were examined. The subjects (high- and low-risk) with moderate/large plaque (n = 96) had higher fibrinogen, thrombin/antithrombin complex and von Willebrand factor, compared to subjects with small/no plaque. The maximum intima-media thickness of the femoral artery was significantly associated with fibrinogen. These associations were independent of current smoking habits. Clinical atherosclerosis was associated with fibrinogen, von Willebrand factor, thrombin/antithrombin complex, plasminogen activator inhibitor activity, mean and maximum intima-media thickness and plaque status of the femoral artery. In conclusion, fibrinogen, von Willebrand factor and thrombin/antithrombin complex were related to plaque occurrence in the femoral artery. Clinical atherosclerosis was associated with fibrinogen, von Willebrand factor, thrombin/antithrombin complex and plasminogen activator inhibitor activity.

Aged↗
PubMedDate not supplied

Effects of subpressor doses of angiotensin II on renal hemodynamics in relation to blood pressure.

The renal hemodynamic response to subpressor doses of angiotensin II (AII; 0.1 and 0.5 ng/min/kg) was investigated in untreated 49-year-old men (n = 50) representing a wide blood pressure range. Renal blood flow, renal vascular resistance (RVR), glomerular filtration rate (GFR), filtration fraction (FF), plasma renin activity (PRA), plasma AII, plasma aldosterone, and the urinary excretion of sodium and norepinephrine were studied. The higher the initial blood pressure the greater was the increase in RVR in response to AII infusion (p less than 0.002), indicating an increased renal vascular reactivity with increase in initial blood pressure. The AII infusion gave a significant rise in RVR in both the borderline and hypertensive group, but gave no increase in RVR in the normotensive group, implying an enhanced sensitivity of the renal vasculature in the borderline and hypertensive group. The increase in RVR was greater in the hypertensive than in the borderline group, i.e., the hypertensives had a steeper dose-response curve than the borderline group, which points to the presence of structural vascular changes in the renal vessels in the hypertensives. The increase in RVR in response to AII was positively correlated to sodium intake and plasma aldosterone concentration, indicating that these two factors might modulate the renal vascular reactivity. These factors could, however, only partly explain that RVR increased more the higher the initial blood pressure. Thus, the results indicate that there is an increased reactivity of the renal vascular bed to AII in essential hypertension. The increased reactivity seems to be mediated through an increased sensitivity of the renal vasculature to AII in mild essential hypertension and also through the presence of structural vascular changes in established hypertension. These factors may lead to a reduced excretion of sodium and water and may therefore be of importance in the development and progression of essential hypertension.

Aldosterone↗
PubMedDate not supplied

Diastolic function of the heart in untreated primary hypertension.

To study left ventricular (LV) diastolic function of the heart in relation to blood pressure (BP) and other signs of hypertensive cardiac and peripheral vascular changes, isovolumic relaxation time and early diastolic filling were determined in four BP groups of untreated 49-year-old men: normotensive subjects (n = 20), men with borderline hypertension (n = 30), mild hypertension (n = 45), and moderate to severe hypertension (n = 24). Isovolumic relaxation time, measured as the distance between aortic closure (A2, phonocardiography) and mitral valve opening (echocardiography), and early diastolic filling, measured as the distance between mitral valve opening and the O point of the apexcardiogram, tended to increase with BP level, and the total interval from aortic closure to the O point (A2O interval) was significantly prolonged in the two groups with mild and moderate to severe hypertension. A prolonged A2O interval (greater than or equal to 117% of expected value at observed heart rate) was seen in several hypertensives, who had no obvious increase in LV wall thickness on M mode echocardiography. This suggests that a prolonged LV relaxation time may be an early sign of cardiac involvement in primary hypertension. In the group with moderate to severe hypertension, an increase in LV wall thickness was seen together with an increase in resistance at maximal dilation in the calf. This supports the theory that when changes in cardiac structure develop they occur in parallel with structural changes also in the periphery.

Blood Pressure↗
PubMedDate not supplied

Left ventricular function in early primary hypertension. Functional consequences of cardiovascular structural changes.

An increase in left ventricular (LV) wall thickness will lead to decreased LV distensibility during both LV passive filling and left atrial contraction. Reduced LV distensibility will change the filling pattern of the left ventricle, and a proportionally smaller part of the stroke volume will be delivered during the passive filling of the preceding diastole and a larger part during late diastole by a more powerful left atrial contraction. With a more pronounced increase in LV wall thickness a reduced distensibility of venous capacitance vessels (functional or structural) will probably help to preserve LV pump function by influencing LV filling and use of the Frank-Starling mechanism. LV wall stress (peak and end-systolic) is high and LV intrinsic contractility is normal or supernormal in early primary hypertension, as judged from the relationship between end-systolic wall stress and different indices of LV function (fractional shortening, mean velocity of circumferential fiber shortening, ejection fraction). Great differences in peak systolic wall stress may be recorded among groups with comparable values for LV end-systolic wall stress, which may be explained by very different degrees of cardiovascular structural changes, with higher values for peak systolic wall stress seen in hypertension caused by high output than those values seen in hypertension caused by high total peripheral resistance. Signs of supernormal LV systolic function are common in high output hypertension, which is also at least partly due to an increase in LV end-diastolic volume and use of the Frank-Starling mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗