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Biomedical subjects

S N Hunyor

Publications and source records attributed to S N Hunyor.

At least 19 recordsLinked to original sources
PubMed1992

Relationship between angiographic infarct size and left ventricular filling.

Infarct size may influence left ventricular filling after acute myocardial infarction. Pulsed Doppler transmitral flow velocities were compared in 47 patients at 7 +/- 6 days following acute myocardial infarction and 47 age-matched controls. Patients were stratified by angiographic infarct size into Groups I, II, III (corresponding angiographic hypokinetic scores less than 2; 2-2.99; greater than or equal to 3 SD/cord). Early diastolic transmitral Doppler flow velocities did not differ between infarct groups but atrial transmitral Doppler flow measurements did: peak A velocity (p = 0.001), A velocity time integral (p less than 0.001), and total velocity time integral (p = 0.001). Compared to controls atrial transmitral Doppler flow was augmented in Group I, whilst atrial and total transmitral Doppler flow were depressed in Group III. Peak A velocity and A velocity time integral were inversely related to infarct size (R = -0.44 to -0.54) and directly to left ventricular ejection fraction (R = 0.59 to 0.65). Large infarct size following myocardial infarction is associated with lower atrial and total transmitral Doppler flow velocities.

Adult↗
PubMed1992

Accuracy of Borg's ratings of perceived exertion in the prediction of heart rates during pregnancy.

When using Borg's 6-20 scale during pregnancy, ratings of perceived exertion (RPE) did not significantly correlate with exercise heart rates (HR) (P greater than 0.05). The HR predicted from RPE significantly (P less than 0.05) underestimated the exercise HR in the second trimester during walking (Group 1: mean difference 16 beats min-1, n = 11), aerobics classes (Group 4: mean 15 beats min-1, n = 48) and circuit training (Group 3: mean 18 beats min-1, n = 24); and in the third trimester during cycling (Group 2: mean 16 beats min-1, n = 12) and aerobics classes (Group 5: mean 11 beats min-1, n = 29). Maximal individual HR under-estimations were large for each physical activity during pregnancy, with values up to 54 beats min-1. Consequently, exercise intensity should not be monitored solely with RPE during pregnancy.

Exercise Test↗
PubMed1991

Voluntary blood pressure control by biofeedback: relationship to psychological characteristics.

1. Psychological characteristics were studied in 25 hypertensives (mean and standard deviation of blood pressure 150/95 +/- 12/5 mmHg), who received blood pressure (BP) biofeedback (BFB). Personality factors and success in BFB-BP modifying ability were correlated and the predictive value of psychological factors was estimated. 2. Questionnaires consisted of a Locus of Control of Behaviour (LCB) scale, the Spielberger state trait anxiety inventory and the Framingham Type A personality inventory. 3. BP was monitored continuously from the finger by volume clamp plethysmography during eight BFB sessions, each with three trials of raising, ignoring and lowering systolic blood pressure (SP). 4. SP was raised/lowered by 12 +/- 11/6 +/- 9 mmHg and heart rate (HR) increased by 10 +/- 3.9/+ 1 +/- 6.1. Ten subjects were able to lower SP by greater than or equal to 5 mmHg (15 +/- 7.5) and raise it by 17 +/- 11. The others achieved no decrease in SP and were also less successful at raising (8 mmHg, P = 0.04). 5. Changes in LCB and trait anxiety correlated with DP rise, whereas type A and pre-study state anxiety correlated with rising HR. Lowering of SP correlated weakly with change in LCB (r = 0.47, P = 0.06). 6. Combinations of psychological factors had independent predictive value for BP and HR change: trait anxiety (P = 0.03) and change in LCB (P = 0.009) with rise in diastolic blood pressure (DP); type A (P = 0.009), pre-study LCB (P = 0.02) and pre-study state anxiety (P = 0.01) with HR rise.(ABSTRACT TRUNCATED AT 250 WORDS)

Biofeedback, Psychology↗
PubMed1991

Relevance of the waterfall phenomenon in continuous finger cuff blood pressure measurements.

1. Finger cuff blood pressure monitors that provide continuous presentation of arterial pressure at the finger are available. 2. The operation of such instruments is based on 'clamping' arterial volume under a pressurized encircling cuff applied to a digit. Blood volume is detected by measuring infra-red transmission across the finger. 3. The compressed veins adopt cuff pressure and combine with the resistance of the peripheral vascular bed at the finger tip to control the blood flow. This results in waterfall behaviour in the veins under the cuff. 4. With the cuff set just 5 mmHg below the undisturbed arterial pressure, adequate flow to the distal finger is maintained. 5. Two potential sources of error affect the finger cuff blood pressure method. These are related to the increase in systolic pressure associated with moving peripherally and the variable value of occluding transmural pressure, both of which depend on muscular tone.

Blood Pressure Monitors↗
PubMed1990

The effect of exercise on circulating immunoreactive calcitonin in men.

Moderate-duration exercise increases serum catecholamine and serum calcium levels and might as a result be also expected to increase the levels of circulating serum immunoreactive human calcitonin (HCT). To explore this possibility, HCT was studied during and after moderate duration symptom-limited dynamic exercise in 13 healthy males, mean age 28 +/- 6.9 (SD) years. The mean duration of exercise using the Bruce treadmill protocol was 14.1 +/- 2.2 (SD) minutes. The mean heart rate (HR) peaked at 185 +/- 6 (SD) bpm which was 96.1% of the predicted maximal HR for age. Values for HCT, uncorrected for changes in plasma volume, showed a minimal decrease in the recovery phase, whilst HCT corrected for changes in plasma volume did not alter during exercise or recovery. The serum parathyroid hormone (PTH) also did not change. At peak exercise, uncorrected but not corrected values for plasma noradrenaline, adrenaline and dopamine had increased significantly. Corrected plasma total calcium increased during recovery. In summary, dynamic weight-bearing moderate-duration exercise did not elevate HCT in healthy males.

Adult↗
PubMed1979

Randomised comparison of methyldopa and oxprenolol for treatment of hypertension in pregnancy.

Fifty-three pregnant women with moderately severe hypertension were randomly allocated to treatment with methyldopa or oxprenolol. There were no significant differences between the groups in age, height, weight, parity, or stage of gestation at the start of treatment. The outcome of pregnancy was better in the group treated with oxprenolol, with greater maternal plasma volume expansion and placental and fetal growth. No intrauterine deaths occurred in either group, and antepartum fetal distress, detected by oxytocin challenge testing, was evident in only one patient, who received methyldopa. This infant, and one other in the methyldopa group, died in the neonatal period. No neonatal deaths occurred in the oxprenolol-treated group. Even in this small number of patients these results were considerably better than those in untreated women with hypertension of similar severity. Apgar scores in both groups were equivalent at birth, while blood sugar concentrations were higher in the oxprenolol group. Oxprenolol appears to be safe and effective in controlling hypertension during pregnancy. There was no evidence of harmful effects on the fetus, and oxprenolol may offer a selective advantage over methyldopa for fetal growth and wellbeing in utero.

Adult↗
PubMed1979

Anatomical accuracy of echocardiographically assessed left ventricular wall thickness.

1. A comparison of direct measurement and M-mode echocardiography in the determination of posterior left ventricular wall thickness was performed in 26 subjects, of whom 21 underwent cardiac bypass surgery; the remainder came to necropsy. 2. In the surgical group a close correlation was demonstrated between direct measurement of posterior wall thickness and the echocardiographic end-diastolic dimension (r = 0.76, P less than 0.001). 3. The necropsy measurement of posterior wall thickness correlated with the echocardiographic end-systolic dimension (r = 0.99, P less than 0.001). 4. These findings confirm that the echocardiographic measurement of posterior wall thickness accurately reflects the anatomical dimension.

Blood Pressure↗
PubMed1979

Haemodynamic profile of angiotensin II antagonism in essential hypertensive patients.

1. The haemodynamic response to antagonistic (10 microgram min-1 kg-1) and agonistic (40 microgram min-1 kg-1) doses of saralasin was studied in young essential hypertensive patients. Blood pressure behaviour alone was thought to be inadequate to describe the response pattern. 2. Pre-saralasin setting of the renin-angiotensin axis was varied with salt intake (15 and 290 mmol of Na+/day) each for 10 days. This failed to influence blood pressure or plasma volume. 3. Antagonist blockade after low salt lowered blood pressure in three patients with the highest plasma renin values. Cardiac output rose in two of these, but it dropped in all others. 4. Decreases in cardiac output occurred with both doses of saralasin and even with suppression of the renin-angiotensin axis. This response is therefore unlikely to be due to removal of myocardial or venous angiotensin effects. 5. The renin-angiotensin system played a part in maintenance of blood pressure only with severe salt restriction and in a small proportion of cases. 6. No heart rate effect was seen with sarcalasin. 7. Blood pressure and total peripheral resistance responses were dependent on pre-(antagonist/agonist) setting, but heart rate and cardiac output were not influenced by this factor.

Adult↗
PubMed1979

Plasma volume contraction: a significant factor in both pregnancy-associated hypertension (pre-eclampsia) and chronic hypertension in pregnancy.

The role of plasma volume in hypertension in pregnancy (pre-eclampsia) was investigated. Significant volume expansion from non-pregnant levels (16.5 +/- 1.60 ml/cm height) was present throughout pregnancy in 189 normal women, reaching 23.1 +/- 1.21 ml/cm at 33-36 weeks amenorrhoea. In another 40 initially normotensive pregnant women who developed hypertension, similar early volume expansion was followed by significant volume contraction in the third trimester, before evaluation of blood pressure in 29 (20.6 +/- 1.26 ml/cm), after it in 11 (18.6 +/- 1.27 ml/cm). Equivalent volume contraction was present in another 44 women studied only after hypertension developed in the third trimester. Oedema had no value as a clinical sign. In another 30 women with chronic hypertension, blood pressure was inversely related to plasma volume (r = 0.822) and to fetal growth (r = -0.710), which was directly related to plasma volume (r = 0.701). Plasma volume depletion plays a significant role in hypertension in pregnancy.

Blood Pressure↗
PubMed1978

Comparison of performance of various sphygmomanometers with intra-arterial blood-pressure readings.

Seven types of sphygmomanometer were used in random order on each of nine hypertensive patients and the readings compared with simultaneous intra-arterial blood-pressure recordings. All the devices gave significantly different values for systolic pressure, and only two measured diastolic pressure without significant error. Systolic pressure was consistently underestimated (range 31-7 mm Hg), and all but one instrument overestimated diastolic pressure (range 10-2 mm Hg). The variability of readings was least with the standard mercury sphygmomanometer and the random-zero machine, while with some of the more automated devices single readings were in error up to -68/33 mm Hg. The strong correlations found between intra-arterial and cuff systolic pressures with all devices tested and significant correlations for diastolic pressure with all but one device indicate that, with one possible exception, the sphygmomanometers would give accurate results where a change in blood pressure was the main concern.

Adult↗
PubMed1978

Side-effects of antihypertensive treatment: a placebo-controlled study.

1. A questionnaire, modified from Bulpitt & Dollery (1973), inquired about 20 symptoms commonly associated with hypertension or its drug therapy in 1017 subjects (age 30--69 years). Groups consisted of (a) active therapy, (b) placebo, (c) no tablets, and (d) a non-study control group. The response rate was 96% in the first three groups and 92% in group (d). 2. The subjects in groups (a), (b) and (c) constituted part of a placebo-controlled, patient-blind intervention study in the treatment of mild hypertension (The Australian National Blood Pressure Study). 3. After age/sex adjustment of the data, only sleepiness and self-assessed depression were found to be more common in the actively treated group. Impotence, failure of ejaculation and nocturia were age-related symptoms. Generally, complaint rate was higher in females. 4. The knowledge of a mild hypertensive condition or its modern drug therapy lead to very few symptoms in a non-hospital population who already have a fairly high 'complaint level'.

Adult↗
PubMed1978

Improvement in foetal growth with treatment of maternal hypertension in pregnancy.

1. A highly significant inverse relationship was found between blood pressure in untreated hypertensive subjects in late pregnancy and birth weight. 2. Reversal of this intrauterine growth retardation was achieved in 19 patients by treatment of hypertension with oxprenolol. 3. No adverse effects from oxprenolol were found in the patients or in their babies.

Birth Weight↗