Geophysical characterization of Saraswati River palaeochannel in parts of Yamuna Nagar and Kurukshetra districts of Haryana, India.

Palaeochannels are remnants of rivers or stream channels filled with younger sediments over the period of time. In ancient times, these rivers/channels were thriving in phenomenal conditions, but due to frequent tectonic activities, they lost the direction of their original path and were gradually either lost or buried under thick beds of younger alluvium. Palaeochannels act as reservoirs for fresh groundwater since they are made up of coarser sediments and were formerly flowing rivers. Depending on the groundwater regime and local topography, these could either be saturated or dry. The palaeochannels have high groundwater potential if saturated. These are ideal sites for artificial groundwater recharge, if dry. The identification of palaeochannels becomes quite challenging if they are buried under thick deposits of finer younger sediments. In the present study, an attempt has been made to characterize the Saraswati River Palaeochannel in parts of Yamuna Nagar and Kurukshetra districts of Haryana by using surface and subsurface geophysical methods. Till date, the palaeochannels in this area were mainly discerned on the basis of remote sensing only; therefore, geophysical characterization of these palaeochannels has been attempted in this study. In surface geophysical methods, electrical resistivity surveys, especially gradient resistivity profiling (GRP) and vertical electrical sounding (VES), were conducted in the study area, while electrical and natural gamma logging was used as subsurface geophysical approaches to identify the coarser sands of buried palaeochannels. The main objective of the study was to characterize the Saraswati River palaeochannel and analyze the quality of the groundwater stored in the palaeochannel in the study area. The findings were compared with the well-log data and were found in good agreement.

Electrocardiographic detection of left ventricular hypertrophy: development and prospective validation of improved criteria.

To develop improved electrocardiographic criteria of left ventricular hypertrophy, individual electrocardiographic voltage measurements were compared with echocardiographic left ventricular mass in a "learning series" of 414 subjects. The strongest independent relations with left ventricular mass were exhibited by the S wave in lead V3, the R wave in lead a VL and the T wave in lead V1 (each p less than 0.001), and by age and sex. Better electrocardiographic detection of left ventricular hypertrophy was achieved by new criteria that stratified QRS voltage and repolarization findings in sex and age subsets. For men, at all ages, left ventricular hypertrophy is suggested by QRS voltage alone when the R wave in lead aVL and the S wave in lead V3 total more than 35 mm. When this voltage exceeds 22 mm, left ventricular hypertrophy is suggested in men under age 40 years when the T wave in lead V1 is positive (greater than or equal to 0 mm), and in men 40 years or older when the T wave in lead V1 is at least 2 mm. For women, at all ages, left ventricular hypertrophy is suggested when the R wave in lead a VL and the S wave in lead V3 total more than 25 mm. When this voltage exceeds 12 mm, left ventricular hypertrophy is suggested in women under 40 when the T wave in lead V1 is positive (greater than or equal to 0 mm), and in women over 40 when the T wave in lead V1 is 2 mm or greater.(ABSTRACT TRUNCATED AT 250 WORDS)

Psychosocial influences on mortality after myocardial infarction.

Psychosocial interviews with 2320 male survivors of acute myocardial infarction, participants in the beta-Blocker Heart Attack Trial, permitted the definition of two variables strongly associated with an increased three-year mortality risk. With other important prognostic factors controlled for, the patients classified as being socially isolated and having a high degree of life stress had more than four times the risk of death of the men with low levels of both stress and isolation. An inverse association of education with mortality in this population reflected the gradient in the prevalence of the defined psychosocial characteristics. High levels of stress and social isolation were most prevalent among the least-educated men and least prevalent among the best-educated. The increase in risk associated with stress and social isolation applied both to total deaths and to sudden cardiac deaths and was noted among men with both high and low levels of ventricular ectopy during hospitalization for the acute infarction.

Education, psychosocial stress and sudden cardiac death.

To explore the hypothesis that low education, associated with high 5-yr sudden-death risk among myocardial infarction survivors demonstrating ventricular arrhythmia, might be a marker for relatively high levels of psychosocial stress, we did telephone interviews with the patients' wives. Analysis of the information obtained on life circumstances and personality attributes resulted in four psychosocial factors that were found to be independent of the patients' educational level. The difference in sudden-death risk in relation to education, given the presence of complex ventricular premature beats in one hour of ECG monitoring, was large and could not be accounted for in multivariate analyses by one or more of these psychosocial factors. Nevertheless, life-table analyses in relation to categorized levels of scores for some of the factors did suggest some modest influences on risk of sudden cardiac death, with severity of disease controlled.

Mortality after first myocardial infarction. Search for a secular trend.

Two earlier studies of prognosis of coronary heart disease among men enrolled in the Health Insurance Plan in the 1960s and 1970s permitted us to examine whether prognosis had improved over this ten-year period. The new comparison involved 1,133 men aged 35 to 64 years who had survived a first acute myocardial infarction and were followed up for mortality after a baseline examination. Mortality estimates were controlled for clinical and demographic differences between the two cohorts by multivariate methods and by comparing subgroups. The analyses showed no difference in long-term prognosis between patients in the two decades. The observations in this population suggest that any contribution of improved medical care to the nationally observed secular decline in mortality from coronary heart disease in the time period studied was probably restricted to the acute stage of myocardial infarction.

Ventricular premature complexes and sudden death after myocardial infarction.

Among 1739 male survivors of myocardial infarction, mortality over 5 years was examined in relation to presence of complex ventricular premature complexes (R on T, runs of two or more, multiform or bigeminal complexes) identified during 1 hour of monitoring. Such arrhythmia was associated with excess risk of death over the entire period. Men with R on T or runs during the hour show a 5-year sudden coronary death rate of 25%, compared with 6% of men free of premature complexes. Men with complex ventricular premature complexes are also at relatively higher risk for nonsudden cardiac death than the other men (5-year mortality 15% and 7%, respectively), but no additional disadvantage was associated with the presence of R on T or runs. Multivariate survival analyses, controlling simultaneously for other important clinical factors, identify complex ventricular premature complexes as the strongest influence on risk of sudden coronary death and congestive heart failure as the strongest influence on risk of other cardiac death.

Ventricular premature complexes in prognosis of angina.

We studied the prognostic role of ventricular premature complexes occurring during 1 hour of electrocardiographic monitoring of 416 men with effort angina who had never had myocardial infarction, and compared mortality over 5 years with that of 1739 men with infarction before first observation. Multivariate analyses of survival identified the presence of ventricular premature complexes in 1 hour of monitoring, the presence of ST-segment depression on the standard ECG, and age as the variables making the most important independent contributions to risk of death (all causes and sudden coronary deaths) among the men with angina. The relatively lower age-adjusted 5-year mortality among men with angina compared with those who had a prior myocardial infarction reflects the lower prevalence in the former group of indicators of myocardial dysfunction, such as ventricular ectopic activity and ST-segment depression.

Relation of education to sudden death after myocardial infarction.

We studied the influence of social and personal characteristics on prognosis among 1739 male survivors of myocardial infarction who had been monitored for one hour at a standard examination and subsequently followed for mortality. Over a three-year period men with little education (eight years of schooling or less) who had complex ventricular premature beats in the monitoring hour had over three times the risk of sudden coronary death found among better educated men with the same arrhythmia (cumulative mortality of 33 per cent and 9 per cent, respectively). No such differential appeared in the absence of complex ventricular premature beats. Neither risk factors for incidence of coronary heart disease nor clinical characteristics affecting prognosis accounted for the differences observed. There was no relation between education level and risk of recurrent infarction.