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S J Piha

Publications and source records attributed to S J Piha.

8 recordsLinked to original sources
PubMed1992

Effect of disease duration on cardiac autonomic reflexes in young patients with insulin-dependent diabetes mellitus.

The association of disease duration with deterioration of cardiovascular autonomic reflexes was studied in two groups of young patients with insulin-dependent diabetes mellitus (IDDM). The mean age of the patients in both groups was 31 years and the mean duration of the disease was 3 (n = 18) and 16 (n = 22) years. No significant difference in group means was seen in the test parameters of autonomic nerve function. However, five patients with long-term disease, but none with short-term disease, had test scores indicating cardiac autonomic neuropathy. It was concluded that (1) the duration of the disease has no overall effect on autonomic nerve function in young patients with IDDM, but (2) a few individuals with IDDM may have some precipitating factors leading to autonomic neuropathy in the course of the disease.

Adult↗
PubMed1992

Cardiovascular reflex tests and the resting heart rate at night and during testing.

Possible effects of environmental stress-induced elevation of the heart rate on the magnitude of cardiovascular autonomic responses were studied in 123 healthy subjects. The nocturnal heart rate was evaluated using ambulatory 24-h ECG monitoring. Some of the cardiovascular responses were found to be significantly weaker in those subjects whose resting heart rate during testing was greater than 10 beats min-1 higher than the resting nocturnal heart rate. It is thus highly important to minimize the environmental disturbances during autonomic testing.

Adult↗
PubMed1992

Changes in autonomic cardiovascular control in mid-pregnancy.

Spectral analysis of heart rate variability was used to study autonomic nervous control in mid-pregnancy. Fifty women (age 22-36 years) with singleton pregnancies (mean duration of gestation 27.7 weeks) and 39 non-pregnant female controls (age 21-39 years) were studied using controlled breathing and orthostatic tests. During spontaneous breathing the overall heart rate variability was lower in pregnant subjects indicating a decreased parasympathetic tone at rest. The decreased parasympathetic tone probably counts for the increased heart rate in pregnancy. The parasympathetic efferent capacity of autonomic cardiac control was found to be similar in pregnant and non-pregnant subjects, as no difference was seen during controlled breathing in periodic heart rate variability between the groups. Standing up caused a similar change in low frequency and mid-frequency bands in both groups, but high frequency heart rate variability increased in pregnant subjects and decreased in the controls indicating an increased sympathetic tone at rest in mid-pregnancy.

Adult↗
PubMed1992

Response of diastolic blood pressure to long-term sodium restriction is posture related.

Eighty-five subjects, aged 31-55 years, suffering from uncomplicated essential hypertension and receiving no regular medication were randomized to sodium restriction and control groups. Systolic (SBP) and diastolic (DBP) blood pressure were measured during an orthostatic test at baseline and after 6 months sodium restriction. The mean daily sodium excretion of 43 treated subjects decreased from 193 +/- 91 mmol to 95 +/- 70 mmol (p less than 0.001). Treated patients were divided on the basis of their mean overall out-patient clinic (OC) DBP decrease in the sitting position during the 6 months (monthly measurements) into sodium-sensitive (DBP decrease greater than 10 mmHg, n = 17), indeterminate (DBP decrease 5-10 mmHg, n = 18) and sodium-resistant (DBP decrease less than 5 mmHg, n = 8) subgroups. At 6 months the level of DBP in the supine position was lower than at baseline in both sensitive and resistant subgroups, whereas in the standing position a lower DBP than at baseline was seen only in the sodium-sensitive subgroup. The magnitude of the subsequent OC DBP decrease was significantly associated with a high baseline seated OC DBP (p less than 0.001) and a high, for baseline OC DBP adjusted orthostatic DBP increase (p = 0.014). Our data suggest that posture should be included in the concept of sodium sensitivity and that an orthostatic test is useful in the prediction of seated and standing DBP decrease produced by moderate, long-term sodium restriction.

Adult↗
PubMed1991

Observations based on 10-years' experience of non-invasive cardiovascular reflex testing of autonomic function from a rehabilitation research centre.

Observations on 1,282 measurements of non-invasive cardiovascular reflex testing of autonomic function in 1,023 control subjects and patients with different disorders are presented. It is suggested that the Valsalva manoeuvre be performed three times rather than once and the highest Valsalva ratio should be used instead of the mean or first of the three ratios. The deep breathing test gives equally reliable information when three breathing cycles are used instead of six. Symptoms were detected in up to 15% of the subjects depending on the test, although the majority of these were minor and transient. The frequency of ventricular/supraventricular extrasystoles increased especially during the Valsalva manoeuvre (+67%/+40%) and post-strain (+49%/+25%) phases and early recovery phase of the orthostatic test (+69%/+156%) and to a lesser degree during deep breathing (+18%/+50%) and handgrip (+36%/-11%) phases compared with the resting phase. However, severe cardiac rhythm disturbances were very rare. 1-2% of the younger (less than 50 years) and 10% of the older subjects were not able to perform the tests adequately. The R-R intervals on which the results are based should be selected carefully, and use of a continuous non-invasive method of blood pressure monitoring should provide further useful information.

Adolescent↗
PubMed1991

Short- and long-term reproducibility of cardiovascular tests of autonomic function in normal subjects.

Ten healthy normal subjects participated in a follow-up study in which the reproducibility of noninvasive cardiovascular autonomic function testing was studied. The tests used were the Valsalva manoeuvre, deep and quiet breathing, standing upright and isometric handgrip exercise. These tests were performed six times within a 2-year period. The reproducibility of these autonomic function tests within a day was evaluated in a separate study involving nine healthy subjects. In this study the tests were performed three times between 08.00 and 15.00. The results indicate that indices based on R-R interval ratios during testing were highly reproducible; that the indices remain reproducible over a 2-year follow up period and that reproducibility within a day was similar to that within longer time periods. The reproducibility of pressor responses to isometric exercise was poor. It is concluded that indices based on R-R ratios are suitable for use in follow up studies of autonomic function.

Adult↗
PubMed1991

Cardiovascular autonomic reflex tests: normal responses and age-related reference values.

One hundred and forty-three healthy unmedicated subjects from a random sample, aged 20-80 years, were examined and cardiovascular autonomic function tests (Valsalva manoeuvre, deep and quiet breathing tests and active orthostatic test) were performed in order to study normal responses to these tests and to determine age-related reference values. Most of the cardiovascular indices reflecting autonomically mediated heart rate responses decline with advancing age and this leads inevitably to the need for age-related reference values. The indices are in general independent of sex but most indices are dependent on resting heart rate. The inter-individual variation is very marked so that the normal ranges are wide, and because the indices diminish with age, the lower reference values are less suitable for use in aged subjects. The reference values make it possible to use the indices for diagnostic purposes in young and middle-aged subjects (up to 65 years), whereas in older subjects the indices can be used in order to exclude autonomic disturbances. Reproducibility of heart rate indices is satisfactory or good whereas reproducibility of blood pressure indices is poor.

Adult↗