Biomedical subjects
Publications and source records attributed to S R Mittal.
Metoprolol caused a significant (P less than 0.001) increase in urine output in rabbits. There was no change in serum sodium concentration but serum potassium levels increased significantly. The most probable mechanism of action was increase in renal blood flow and glomerular filtration rate.
The R/S ratio was calculated in all the six conventional precordial leads in 27 cases of emphysema and 23 cases of old anteroseptal myocardial infarction, all having poor R wave progression in the precordial leads. An R/S ratio greater than or equal to 3.5 in lead V5 was found to be most sensitive (87%), specific (83%) and accurate (85%) in differentiating poor R wave progression of old anteroseptal myocardial infarction from that due to emphysema.
We studied the effect of concomitant administration of chlordiazepoxide on the negative chronotropic effect of metoprolol in rabbits. Chlordiazepoxide administration for more than two weeks partly reversed the effect of metoprolol in three out of five rabbits, probably through hepatic enzyme induction.
This study included 25 hypertensive patients with "normal" standard 12-lead scalar electrocardiogram and an equal number of age- and sex-matched controls. We recorded routine twelve leads, posterior chest leads, ensiform lead, right-sided precordial leads, lead CM5 and oesophageal electrocardiogram at different levels in all individuals. In addition we recorded an unconventional unipolar lead with the chest electrode placed on the thoracic seven spine. We also recorded some unconventional bipolar leads, in each instance using V5 as the positive electrode and the T7 spine, or the oesophageal electrode as negative. We observed that the T wave height of 20% or less of R wave amplitude in lead I was highly specific (92%) and sensitive (76%) in detecting early left ventricular hypertrophy in hypertensive patients, with the standard 12-lead electrocardiogram considered "normal" by conventional criteria. The T wave amplitude of 15% or less of the accompanying QRS in lead V6 was nearly equally diagnostic (specificity 88% and sensitivity 68%). An S wave of 0.3 mV or more in the bipolar lead recorded with the positive electrode at V5 and the negative electrode on T7 spine was also highly specific (80%) and sensitive (72%). Isoelectric or inverted T wave in lead V8, ST segment depression and T wave inversion in lead CM5 and ST segment depression in the bipolar lead recorded with the positive electrode at the V5 position and negative electrode at the atrial level of the oesophagus were highly specific (100%) but had a low sensitivity (40, 36, 16, and 28%, respectively). Combined lead V8 and lead I further improved the sensitivity to 96% without decreasing the specificity.
Oesophageal electrocardiograms were recorded in 25 normal persons, 20 patients with chronic bronchitis and predominant emphysema without right ventricular hypertrophy and 25 patients with chronic cor pulmonale as an end result of chronic obstructive pulmonary disease. At ventricular level, patients with chronic cor pulmonale had higher P wave height, lower Q wave depth, lower R wave height, deeper S waves and lower R/S ratio as compared to the group with emphysema. In terms of the transitional zone, patients with cor pulmonale had smaller Q waves and a lower Q/R ratio. At atrial level, the patients with cor pulmonale had higher heights of the P and R waves and a lower Q/R ratio. All these differences were highly significant statistically (P less than 0.001). An R/S ratio of less than 2.5 at ventricular level had high sensitivity (96.0%), specificity (100%) and accuracy (98%) in diagnosing right ventricular hypertrophy in cases of chronic obstructive pulmonary disease. This criterion obtained from the oesophageal electrocardiogram is much more sensitive and accurate than those obtained routinely from the surface electrocardiogram in diagnosing right ventricular hypertrophy in cases of chronic obstructive pulmonary disease.
A case of ectopic atrial rhythm with progressively increasing exit block is reported in a case of ischemic heart disease. Such a rhythm suggests significantly diseased atria which are unable to sustain a regular rhythm for a long period. This arrhythmia should warn the clinician of impending atrial arrest.
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We studied the effect of oral potassium supplement alone and with spironolactone on the lithium-induced T wave change in rabbits. T wave flattening produced by lithium was not affected by oral potassium supplementation. Oral spironolactone therapy effectively reverted as well as prevented lithium-induced T wave flattening.
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We studied the protective effect of metoprolol on emetine induced T wave changes in rabbits. None of the rabbits who were beta-blocked before administration of emetine develop the T wave changes observed consistently in the control group. These observations support our clinical impression that emetine-induced T wave changes are produced because of stimulation of peripheral sympathetic nervous system and can be effectively prevented by prior and concomitant beta-blockade.
An unusual case of Holt-Oram syndrome with arachnodactyly, high arch palate, thoracic scoliosis and hypoplasia of the left radial artery is reported. The relevant literature is discussed and the importance of vascular hypoplasia in genesis and localization of the skeletal deformities of this syndrome is stressed.
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