Tilt table testing in the diagnostic evaluation of presyncope and syncope: a case-series report

Tilt table testing has long been used as a standard tool in the diagnostic evaluation of syncope. However, differences of opinion exist with regard to its utility in the evaluation of patients with only presyncopal attacks. We present the results of drug-free, 70-degree head-up tilt table tests (maximum duration of 45 minutes), conducted between May 2002 and May 2003 in the Department of Physiology at JIPMER. This series consisted of both male and female patients (age 6-79 yr) with presyncope (n = 43), unexplained syncope (n = 43) and asymptomatic healthy volunteers without a history of syncope (n = 14). 28 out of 43 patients with unexplained syncope had a history of recurrent syncope while the remaining 15 had only 1 episode. 2 out of 43 patients (4.6%) with a history of only presyncopal attacks had a positive test (induction of intense presyncope and/or syncope accompanied by hypotension and/or a relative bradycardia). 21 out of 43 patients (49%) with a history of syncope had a positive test. 7 had vasodepressor syncope due to hypotension, 6 had cardioinhibitory syncope characterized by asystole and 10 had a mixed form of the vasovagal syndrome characterized by hypotension as well as bradycardia. 18 out of 28 patients (64%) with recurrent unexplained syncope had a positive test. All fourteen healthy volunteers had a negative test. We conclude that tilt table testing is useful in the diagnostic evaluation of patients with unexplained syncope, especially those with recurrent syncope, but not in the evaluation of patients with presyncope alone.     

Short-Term Heart Variability and Oxidative Stress in Newly Diagnosed Essential Hypertension

We sought to evaluate oxidative stress parameters like malondialdehyde, total antioxidant status, and time, frequency domain heart rate variability indices in newly diagnosed untreated hypertension. We also sought to study the correlation between heart rate variability and oxidative stress parameters in normotensive and newly diagnosed untreated essential hypertensives. Fourteen normotensive males and 36 newly diagnosed male hypertensives were enrolled for the study. Malondialdehyde, total antioxidant status, and heart rate variability in the frequency and time domain were studied in the hypertensive and normotensive group. Malondialdehyde was significantly higher in the hypertensive group, whereas total antioxidant status was significantly higher in the control group. SDNN, RR triangular index, RMSSD, log ₁₀ low-frequency power, log ₁₀ high-frequency power, log ₁₀ total power, and heart rate variability during deep breathing test was significantly lower in hypertensive patients compared to normotensive controls. SDNN, RMSSD, high-frequency power, and high-frequency power normalized had significant negative correlation with malondialdehyde. Low-frequency power normalized positively correlated with malondialdehyde. Total antioxidant status had a significant negative correlation with blood pressure. The study gives further evidence for a decreased heart rate variability and elevated oxidative stress in hypertension.     

Modulation of cardiovascular response to exercise by yoga training

This study reports the effects of yoga training on cardiovascular response to exercise and the time course of recovery after the exercise. Cardiovascular response to exercise was determined by Harvard step test using a platform of 45 cm height. The subjects were asked to step up and down the platform at a rate of 30/min for a total duration of 5 min or until fatigue, whichever was earlier. Heart rate (HR) and blood pressure response to exercise were measured in supine position before exercise and at 1, 2, 3, 4, 5, 7 and 10 minutes after the exercise. Rate-pressure product [RPP = (HR x SP)/100] and double product (Do P = HR x MP), which are indices of work done by the heart were also calculated. Exercise produced a significant increase in HR, systolic pressure, RPP & DoP and a significant decrease in diastolic pressure. After two months of yoga training, exercise-induced changes in these parameters were significantly reduced. It is concluded that after yoga training a given level of exercise leads to a milder cardiovascular response, suggesting better exercise tolerance.     

Cardiovascular autonomic regulation in subjects with normal blood pressure, high-normal blood pressure and recent-onset hypertension

1. In the present study, we tested the hypothesis that heart rate variability (HRV) is reduced in recent-onset hypertension and that pressor responses to standard autonomic reflex tests are not any different in hypertensives compared with normotensives. We also hypothesized that subjects with high-normal blood pressure (BP) would be distinguishable from normotensives on the basis of short-term HRV indices. 2. Three groups of subjects, each consisting of 15 men and 10 women, were examined. The first group consisted of subjects with recent-onset hypertension who were not taking antihypertensive medication (mean (+/-SD) age 50 +/- 12 years; BP >/= 140/90 mmHg), the second group consisted of subjects with high-normal BP (mean age 46 +/- 13 years; BP 130-139/85-89 mmHg) and the third group consisted of subjects with normal BP (mean age 48 +/- 12 years; BP < 120/80 mmHg). The aim was to characterize the autonomic state in each group. 3. Blood pressure, heart rate (HR), indices of short-term HRV during supine rest and quiet standing, HR variation during timed deep breathing (HRVdb) and pressor responses to the cold pressor test and sustained isometric handgrip were compared between the groups. 4. Although the three groups were comparable (P > 0.1) in terms of mean HR and low-frequency (LF) power expressed in normalized units at rest and during quiet standing, the standard deviation of normal-to-normal RR intervals (SDNN) during supine rest, LF and high-frequency spectral powers during supine rest and HRVdb were lowest in hypertensives (P 相似文献   

Sex Differences in Short‐Term Heart Rate Variability in Patients With Newly Diagnosed Essential Hypertension

The authors report the results of the analysis of heart rate variability (HRV) indices during 5 minutes of supine rest and 5 minutes of standing and conventional indices of autonomic function in 69 men and 51 women with untreated newly diagnosed hypertension matched for body mass index and resting blood pressure. Mean RR interval, standard deviation of normal‐to‐normal RR intervals, low‐frequency RR spectral power, HRV during deep breathing at 6 breaths per minute, and the 30:15 ratio (maximum RR interval 30th beat/minimum RR interval 15th beat) were significantly lower in women (P=.01, .02, .001, .04, .01, respectively) compared with men. Low frequency RR in normalized units was lower in women in the supine position alone (P=.03). HRV was significantly lower in women with untreated newly diagnosed hypertension compared with men. The authors interpret these results as indicating an increase in baseline cardiac sympathovagal balance in female hypertensive patients.