Prof. J.P.N. Mishra
Duren et al (2008) found that central arterial stiffness is an accepted risk factor for cardiovascular disease. While aerobic activity is associated with reduced stiffness the influence of practicing yoga is unknown. The aims of this study were to: 1) evaluate arterial stiffness in middle-aged adults who regularly practiced yoga, performed regular exercise, or were inactive, 2) evaluate the reproducibility of arterial stiffness measured in the left and right carotid artery and by pulse wave velocity (PWV). Twenty six healthy subjects (male and female, 40-65 yrs old) were tested on two separate days. Carotid artery dispensability (DC) was measured with ultrasound. Physical activity was determined by questionnaire. Yoga and aerobic subjects had similar physical activity levels. Yoga and aerobic groups were not different in either DC (p = 0.26) or PWV (p = 0.21). The sedentary group had lower DC and higher PWV compared to the aerobic and yoga groups (both, p < 0.001). Stiffness measures were reliable day to day (coefficients of variation -2.5%) and similar between left and right arteries (CV = 2.2%).
It was concluded that physical activity was a strong predictor of both measures of arterial stiffness, although other factors such as nutritional status need to be accounted for. An independent effect of practicing yoga could not be detected. Stiffness measures were reproducible and left and right sides were consistent with each other. Physical activity had the greatest influence on arterial stiffness in middle-aged men and women. This is consistent with previous studies that have shown that high physical activity is associated with reduced arterial stiffness.
Garrido et al (2005) found prognostic value of exercise echocardiography in patients with diabetes mellitus and known or suspected coronary artery disease. To assess the prognostic value of exercise echocardiography in subjects who had diabetes, 214 patients were observed, who had 28 hard cardiac events (cardiac death in 15, myocardial infarction in 13) during a follow-up of 44 +/- 16 months. Independent risk factors for predicting cardiac events were insulin therapy (odds ratio 2.313), peak left ventricular ejection fraction (odds ratio 0.973), and ischemia detected by exercise echocardiography (odds ratio 2.513).
Tanaka et al (2004) found that arterial compliance in trained middle aged and older groups was 20 to 35% higher than in their sedentary groups, consistent with aerobic and yoga groups (32% higher than our sedentary group).
Khattab et al (2003) stated that relaxation techniques are established in managing of cardiac patients during rehabilitation aiming to reduce future adverse cardiac events. It has been hypothesized that relaxation-training programs may significantly improve cardiac autonomic nervous tone through parasympathetic stimulation. However, this has not been proven for all available relaxation techniques. This assumption was tested by investigating cardiac vagal modulation during yoga. 11 healthy yoga practitioners (7 women and 4 men, mean age: 43 ± 11; range: 26-58 years) were examined. Each individual was subjected to training units of 90 min once a week over five successive weeks. During two sessions, they practiced a yoga program developed for cardiac patients by B.K.S. Iyengar. On three sessions, they practiced a placebo program of relaxation. On each training day they underwent ambulatory 24 h Holter monitoring. The group of yoga practitioners was compared to a matched group of healthy individuals not practicing any relaxation techniques. Parameters of heart rate variability (HRV) were determined hourly by a blinded observer. Mean RR interval (interval between two R-waves of the ECG) was significantly higher during the time of yoga intervention compared to placebo and to control (P < 0.001 for both). The increase in HRV parameters was significantly higher during yoga exercise than during placebo and control especially for the parameters associated with vagal tone, i.e. mean standard deviation of NN (Normal Beat to Normal Beat of the ECG) intervals for all 5-min intervals (SDNNi, P < 0.001 for both) and root mean square successive difference (rMSSD, P < 0.01 for both). In conclusion, it was said that relaxation by yoga training is associated with a significant increase of cardiac vagal modulation. Since this method is easy to apply with no side effects, it could be a suitable intervention in cardiac rehabilitation programs.
Lindqvist (2001) recorded patterns of QT/QS2 ratio in vasomotorically labile young men. The QT/ QS2 ratio in seven 21-year-old men with a history of vasomotor lability was measured when they were resting supine and during orthostatic, valsalva and diving reflex tests. The vasolability was characterized by an abnormal sympathicotonic heart rate (HR) response to the orthostatic test and vacillating inferoapical T waves in the ECG. The results of the vasolabile subjects were compared to those of seven fit control subjects of the same age. In spite of equal HR's in both groups the vasolabile subjects' QT/Q2 ratio constantly exceeded 1.00 during the whole test protocol and it was higher than of the controls (Pd"0.04). The reversed QT/QS2 relationship in the test subjects seemed to be due both to a prolongation of the QT time and a shortening of the QS2 time. This difference prevailed throughout although the reaction pattern to autonomic stimulations was equal in both groups. They considered an inadequate neural control of the heart, possibly with metabolic and haemodynamic interactions, responsible for the prolongation of the electrical systole in relation to the electromechanical systole in the heart of the vasomotorically labile subjects.
Konar et al (2000) in his study observed that Sarvangasana (SVGN) is a head-down-body-up postural exercise in a 'negative g' condition. Though highly recommended as one of the three best of all the asanas it has not yet been studied for. Its very obvious effects on the cardiovascular (CV) functions. It is one of the first systematic investigations on SVGN employing echocardiographic analysis in eight healthy male subjects before and after a practice of this asana twice daily for two weeks. The resting heart rate (HR) and left ventricular end diastolic volume (LVEDV) were significantly reduced (P < 0.02, P < 0.01 respectively) after practicing this asana. A tendency towards a mild regression of the left ventricular mass was noticed in ECG, though it was not statistically significant The CV responses to acute 45 degrees head-down tilt (HDT) in a tilt table was not altered after practicing this asana. Also there was no orthostatic intolerance during the 3-5 min period of 70 degrees head-up tilt (HUT). These results strongly indicate that further studies of this asana performed for a longer period is most likely to yield very significant observations of applied value.
Shah (1998) evaluated cardiovascular functions in coronary heart disease patients. Out of the 10 patients, eight had heart attack in the past and two had angina without any history of heart attack in the past. Of the eight patients of heart attack, five had angina which had developed after the heart attack. In 5 out of the 10 cases, there was history of established hypertension. Moreover, in 2 other patients there was a history of transient rise of blood pressure. Three patients never had any high blood pressure.
Four out of 10 had history of high blood sugar levels and out of these, three had only borderline blood sugar levels. Apart from clinical examination, X-ray chest, ECG and blood fats (Serum cholesterol, triglycerides, HDL cholesterol), stress test was done in four patients. In three of these the test was positive, while in one case of anterosepatal infarct, the test was negative. Gated blood pool studies were available in four and all showed coronary heart disease. Coronary angiography result was available in one patient and it showed involvement of left anterior descending and circumflex artery block of significant degree. 2D Echocardiogram was done during the coronary camp and was repeated after three months. This was done to obtain a direct evidence of the benefit or otherwise arising out of the camp.
During the camp, the patients stayed in the camps for 7 days. They followed a pattern of unhurried regular lifestyle. They spent about three hours in yoga which included about 45 minutes of walk For about an hour a day they were informed about yoga and its principles and they were informed about the art of mental relaxation. Their diet was simple and nourishing, low in fats, salts and spices For about an hour a day, the patients were informed about the risk factors of heart attack, about high blood pressure, about the importance of blood fat levels, about weight reduction and about the regression of atherosclerosis. In other words, the patients were told how to prevent heart attack and how to reverse the process of atherosclerosis in the coronary arteries. All the ten patients were well motivated.
Only one could not follow diet, as he had excessive bleeding per rectum. Remaining nine patients could follow either walking exercise or yogasana or both regularly. At the end of three months, six out of seven who had angina showed significant improvement in the symptoms The three asymptomatic patients had definite improvement in their approach to the disease and could relax much better. In three out of five cases, ECG showed improvement. 2D Echo was repeated in all the ten cases and it showed a significant improvement in 4, slight in 3 and no change in 4. In conclusion it was noted that the coronary care camp helped the patients to understand their disease and thereby to take effective steps in a much better way. No patient showed any deterioration. Six out of seven who had angina showed significant improvement. This improvement was supported by the improvement in ECG or ECHO or both in most of the cases. In spite of the small number of the patients in the study, the results are striking. It indicates that a ftirther study of at least 100 cases should be done to come to definite well-supported conclusions.
Kupari et al (1994) found a significant correlation between arterial dispensability and self-reported physical activity.
Satyanarayana et al (1992) conducted a study on Santhi Kriya s effect and reported that sant hi kriya is a mixture of combined yogic practices of breathing and relaxation. Preliminary attempts were made to determine the effect of santhi kriya on certain psycho-physiological parameters. Eight healthy male volunteers of the age group 25.9 +/- 3 (SD) years were subjected to santhi kriya practice daily for 50 minutes for 30 days. The volunteer's body weight, blood pressure, oral temperature, pulse rate, respiration, ECG and EEG were recorded before and after the practice on the 1st day and subsequently on 10th, 20th and 30th day of their practice.
They were also given a perceptual acuity test to know their cognitive level on the 1st day and also at the end of the study i.e., on the 30th day. Results indicate a gradual and significant decrease in the body weight from 1st to 30th day (P less than 0.001) and an increase in alpha activity of the brain (P less than 0.001) during the course of 30 days of santhi kriya practice. Increase of alpha activity both in occipital and pre-frontal areas of both the hemispheres of the brain denotes an increase of calmness. This study also revealed that santhi kriya practice increases oral temperature by 3° F and decreases respiratory rate significantly (P less than 0.05) on all practice days. Other parameters were not found to be altered significantly. It was concluded that the santhi kriya practice for 30 days reduces body weight and increases calmness.
Stancak et al (1991) studied yogic high-frequency respirationkapalabhati (KB) in 24 subjects from a point of rhythmicity. Respiratory movements, blood pressure and R-R intervals of ECG were recorded in parallel and evaluated by spectral analysis of time series. Respiratory signals during KB were modulated by 0.1 Hz rhythm in 82% of experiments. This component was also present in R-R intervals and blood pressure during KB. Frequency (0.2-0.3 Hz) was observed in 67% of respiratory records. The presence of the component 0.2-0.3 Hz in respiration was dependent on resting respiratory frequency. This frequency component was reduced in R-R intervals but increased in blood pressure during kapalabhati as compared to that at rest. The occurrence of both frequency components in respiration during KB supports the hypothesis about the integrative role of cardiovascular and respiratory rhythms in physiological states characterized by altered respiratory frequency.
Vincent (1991) Patients with the Romano-Ward inherited long QT syndrome have an incompletely defined cardiac sympathetic system abnormality and exhibit ventricular arrhythmias during exercise, fear and anxiety. Treadmill and bicycle exercise were used to modulate cardiac autonomic activity in 27 Romano-Ward subjects and 27 normal controls. The heart rate, and the QT, QTc and QT/QS2 (ratio of electrical to mechanical systole) intervals were compared. Subjects with long QT were compared with normal. Those with a long QT interval had the following results: similar resting heart rates; lower rates during moderate (151.6 vs 169.6 beats/min, p = 0.04) and maximal (155.9 vs 182.1 beats/min, p = less than 0.001) exercise; an abnormal QT cycle-length relationship, with failure of the QT to shorten normally with increasing heart rate; an increase in QTc versus a decrease in normal; supine rest QT/QS2 ratio of 1.12 vs 0.93, p = 0.001; and an exercise QT/QS2 that increased by 30%, from 1.12 at rest to 1.45, versus 15%, in normal, from 0.93 to 1.07, p = 0.001. The lower heart rates and excessively prolonged QT/QS2 ratios during exercise further support an abnormality of, or abnormal cardiac response to, sympathetic activity. A QT/QS2 greater than 1.0 at rest, an exercise QT/QS2 ratio greater than 1.17, and an increase in QTc during moderate exercise may be helpful diagnostic findings in patients with borderline long QTc intervals at rest.
Cuomo et al (1988) studied Relationship between QT/QS2 ratio and angiographic severity of coronary heart disease. The relationship between QT/QS2 ratio and angiographic severity of coronary heart disease (CHD) was determined in 99 patients who underwent coronary arteriography because of chest pain. Sixteen control patients with normal coronary arteriograms and normal left ventricular function and 83 patients with angiographic evidence of CHD were studied. QT/QS2 ratio and systolic time intervals were calculated from polygraphic recordings taken at rest. In control subjects QT/ QS2 ratio was significantly shorter (0.91 +/- 0.04) than in patients with double (0.95 +/- 0.07; p less than 0.05 versus control subjects) and triple vessel coronary artery disease (0.95 +/- 0.05; p less than 0.05 versus control subjects).
QT/QS2 ratio was significantly higher (p less than 0.01) in patients with 3 areas or more of left ventricular abnormal wall motion (LV AWM) (0.98 +/- 0.05) than in patients with none (0.92 +/-0.06) or just 1-2 areas (0.93 +/- 0.06) of LV AWM. Multiple regression analysis revealed no relation between the number of coronary stenosis and QT/QS2 (t = 0.86; p = NS), while a relation was identified between the number of a synergic segments and QT/QS2 (t = 1.99; p less than 0.05).
A significant correlation was found between QT/QS2 and PEP/LVET (r = 0.39; p less than 0.001). Setting the upper normal limit at 2 standard deviations from the mean of control subjects (QT/QS2 = 0.99), QT/QS2 criterion yielded a 30% sensitivity, a 94% specificity and a 96% predictive accuracy in diagnosing CHD. The investigator concluded that in CHD patients QT/QS2 ratio is influenced by the extension of LV AWM. Although a low sensitivity may limit its use, a QT/QS2 value higher than 0.99 in a patient with chest pain strongly suggests CHD and thus this criterion may be diagnostically useful.
Ferro (1986) investigated the relationship between QT interval and QS2 (electromechanical systole) during exercise and recovery in patients with coronary artery disease (CAD) and exercise-induced myocardial ischemia (n = 12), and in age-matched controls (n = 20). Upright bicycle exercise was performed (50 watts/min + 20 watts/min every 2 min), recording electrocardiographic lead 2 (100 mm/sec) for QT and QS2 measurement at rest, at each step of uninterrupted exercise and every 60 sec during a 3-min recovery period.
Resting data showed a QT less than QS2 finding in both groups; during exercise, QT and QS2 decreased. The values of QT and QS2, collected at each step of exercise and plotted against heart rate (HR) separately for both groups, showed a significant correlation coefficient. Comparing the regression lines of HR-QT and HR-QS2 separately for both groups, we found that both intervals decreased in parallel and the mean QT remained shorter than QS2 in both groups during exercise. The QT/QS2 ratio remained unchanged significantly during exercise and recovery in CAD. In control subjects, the ratio remained unchanged during exercise and the first min of recovery, while a significant change was detected in late (2,3 min) recovery from an adrenergic-induced effect.
The mean exercise-induced response of QT-QS2 relationship includes a QT less than QS2 pattern in both groups. In CAD patients, an abnormal pattern was found in two patients during recovery by a relative prolongation of QT, suggesting the possibility of a risk factor for dangerous arrhythmias or sudden death.
Kothari et al (1973) reported the case of a yogi who was confined to a small underground pit for eight days and continuously monitored with an EKG. From the second day until the eighth, EKG activity was below a recordable level, indicating that the yogi had either stopped his heart or greatly decreased its electrical activity. The authors believe that the yogi could not have tampered with the EKG leads without creating an obvious electrical disturbance.
