Comparative study of exercise-induced ventricular arrhythmias in normal subjects and patients with documented coronary artery disease.

The incidence, types and patterns of emergence of treadmill exercise induced ventricular arrhythmias were studied in 482 subjects with and without coronary heart disease. All subjects were free of premature ventricular complexes at rest and were classified into groups on the basis of their clinical status. In Group 1A were 141 patients with chest pain and normal coronary arteriograms and in Group IB 144 age-matched subjects free of clinical evidence of heart disease. Group II consisted of 197 patients with chest pain and arteriographically documented coronary artery disease. Patients in Group IA and II exercised to at least 85% of their predicted maximal heart rate or until chest pain occurred. Subjects in Group IB underwent maximal exercise testing. The total incidence of exercise-induced ventricular arrhythmias was 16% in Group IA, 44% in Group IB and 29% in Group II. However, when exercise heart rate at the time of appearance of ventricular arrhythmias was taken into account the incidence of exercise-induced ventricular arrhythmias up to a heart rate of 130/min was 27% in the patients with documented coronary artery disease (Group II) compared with rates of 9 and 6%, respectively, for Groups IA and IB (P less than 0.001). The incidence rates of multifocal ventricular premature complexes, ventricular tachycardia and ventricular premature complexes at a rate of more than 10/min were also significantly greater at submaximal heart rates in the patients with coronary disease. Patients with three vessel coronary artery disease and abnormal left ventricular wall motion had a significantly greater incidence of exercise-induced ventricular arrhythmias. The incidence of exercise-induced ventricular arrhythmias in patients with coronary disease and a positive S-T segment response was not significantly increased.

Usefulness of Q-wave response to exercise as a predictor of coronary artery disease.

In lead CM5, the Q-wave response to exercise has been reported as an effective index in predicting coronary artery disease (CAD) and CAD with left anterior descending (LAD) disease. The purpose of this study was to verify these findings when the Q wave was analyzed in lead CC5 in 135 patients. The sensitivity for abnormal ST depression was 77%, specificity 83% and predictive value 78%. The corresponding values for the abnormal Q-wave response (reduction or no change in Q-wave amplitude) were 70%, 61% and 59%. These differences (except sensitivity) were significant. When either a positive ST or Q-wave response was used, sensitivity, specificity and predictive value did not significantly increase compared with the ST segment alone. In addition, only 45% of normal subjects with false-positive ST depression had a normal Q-wave response (increase) and 57% of patients with false-negative ST responses had an abnormal Q-wave response. When a positive response for CAD with an LAD lesion and for multivessel CAD with LAD narrowing was defined as having a Q-wave reduction, the sensitivities were extremely low (15% and 17%), but both the specificities and the predictive values were 100%. Therefore, the Q-wave analysis in lead CC5 is no more sensitive for detecting CAD than the ST-segment response. However, when a decreased Q-wave amplitude is observed, multivessel CAD and LAD narrowing can be predicted.

Prevalence and reproducibility of exercise-induced ventricular arrhythmias during maximal exercise testing in normal men.

The occurrence of ventricular arrhythmias at rest or during ordinary daily activities has been implicated as a risk factor for future coronary-related events and sudden death. However, the clerical significance of exercise-induced ventricular arrhythmias remains uncertain. To assess the prevalence and reproducibility of such arrhythmias, two serial maximal treadmill exercise tests were performed in a study population of 543 male Indian State policemen at an average interval of 2.9 years. Four hundred sixty-two subjects were clinically free of evidence of cardiovascular disease, and 81 had evidence of definite or suspected cardiovascular disease. The prevalence of exercise-induced ventricular arrhythmias during the first test was 30% in men aged 25 to 34 years, 32% in those aged 35 to 44 years and 36% in those aged 45 to 54 years. The prevalence rate in these age groups with repeat testing was 36, 38 and 42%, respectively. These differences were not statistically significant. The group with definite or suspected cardiovascular disease had a greater prevalence of exercise-induced ventricular arrhythmias than normal subjects during both tests but the prevalence rate with repeat testing remained constant. The occurrence of exercise-induced ventricular arrhythmias was reproducible in individual subjects during the second test in 55% of 25 to 34 year olds, 58% of 35 to 44 year olds and 62% of 45 to 54 year olds. Thus, individual reproducibility in two consecutive tests was only slightly greater than reproducibility by chance alone. The group with known or suspected cardiovascular disease demonstrated a trend toward greater reproducibility with repeat testing. Exercise-induced ventricular arrhythmias were not reproducible by type or complexity. The marked variability of exercise-induced ventricular arrhythmias during repeat maximal exercise testing in a clinically normal population appears to negate the usefulness of this finding during a single test as a marker of future cardiovascular disease. Nevertheless, subjects whose arrhythmias were reproducible may form a group destined to manifest clinical cardiovascular disease in long-term follow-up studies.

Comparative study of cardiovascular function and ventricular premature complexes in smokers and nonsmokers during maximal treadmill exercise.

Maximal treadmill exercise tests were performed by 586 male members of the Indiana State Polic Force who were free of clinical evidence of cardiovascular disease. The study population was categorized into groups according to cigarette smoking experience and subgroups according to age and number of pack-years of exposure. There were 176 nonsmokers (30 percent), 268 current smokers (46 percent) and 142 former smokers who had abstained for at least 1 year (24 percent). No statistically significant differences were found in the prevalence of exercise-induced ventricular premature complexes when current smokers were compared with nonsmokers or former smokers either as a group or as subgroups classified by age. The duration of maximal exercise and the peak heart rate and systolic blood pressure during maximal exercise were compared for each group. The duration of maximal exercise was significantly shorter in smokers (P less than 0.001) and former smokers (P less than 0.005) than in nonsmokers. Maximal systolic blood pressure during exercise was greater in smokers than in nonsmokers (P less than 0.01) but did not differ significantly between nonsmokers and former smokers. Maximal heart rate during exercise was significantly lower in smokers (P less than 0.01) and former smokers (P less than 0.01) than in nonsmokers. In conclusion, there was a statistically significant difference in the duration of exercise and the maximal heart rate and systolic blood pressure attained during exercise between men who smoked and nonsmokers, but the prevalence of the exercise-induced ventricular premature complexes did not appear to be influenced by smoking habits.

Prevalence and magnitude of S-T segment and T wave abnormalities in normal men during continuous ambulatory electrocardiography.

Fifty asymptomatic normal male volunteers, mean age 44.6 years (range 35 to 59), were prospectively studied to ascertain the prevalence and magnitude of S-T segment and T wave changes detected during continuous ambulatory electrocardiographic monitoring. Transient S-T segment depression of 1.0 mm or more was recorded in 15 (30 percent) of the subjects, and labile T wave inversion of up to 3 mm occurred in an additional 18 (36 percent). The presence of ST-T changes during monitoring did not correlate with age, daily activity status or heart rate. There was also no correlation with the S-T segment response or work performance during treadmill exercise testing. It is concluded that S-T segment depression and T wave inversions are commonly observed during ambulatory electrocardiographic monitoring of normal men. Therefore, similar changes observed in patients with coronary artery disease should be interpreted with caution.

S-carboxymethylcysteine in the fluidification of sputum and treatment of chronic airway obstruction.

The clinical results and changes in sputum found in both a short-term inpatient trial and a subsequent long-term outpatient investigation (three-month double-blind controlled study) of 82 patients with chronic bronchitis treated with a new mucolytic agent, S-carboxymethylcysteine (Mucodyne), are reported. Fluidification of sputum with reduction in certain measurements of the viscosity of morning sputum aliquots, associated with improvement in the ability to cough up bronchial secretions, significant increase in sputum volume output, and improvement in ventilation (as estimated by the forced expiratory volume in one second), were observed in both trials as dose-related responses, with an increase in the ease of expectoration and a reduction in cough frequency and dyspnea. Therapy with S-carboxymethylcysteine was well tolerated, and there were no serious adverse effects, either immediate or delayed. We suggest that the effect of the drug in fluidifying sputum may be due to a mucoregulatory mechanism which reverses the sputum macromolecular disturbances seen in chronic bronchitis.

The measurement of thyroxine in urine using a competitive protein binding technique.

The competitive protein vinding assay for the measurement of thyroxine in blood serum was modified for the measurement of thyroxine in urine. Samples of urine of 1 to 5 ml volume containing 0 to 5 ng/ml could be assayed with 100% recovery, and above this range, up to 10 ng, recoveries were higher due to non parallelism with the standard curves. Tests carried out using porcine serum albumin indicate that results obtained by the method are not likely to be affected by proteinuria. The cross reaction with triiodothyronine was 25%. Analysis of urine samples stored at 25 degrees C gave higher values than those stored at +4 degrees C or --20 degrees C over similar periods. These increases at 25 degrees C were of the same magnitude as those obtained by acid hydrolysis of urinary thyroxine conjugates.

Preliminary investigations of urinary thyroxine excretion by young pigs.

Total and unconjugated thyroxine were measured in pig urine and the effect of several forms of stress on the urinary thyroxine excretion of young pigs was investigated. There was considerable variation in the daily urinary thyroxine excretion and the rate of excretion tended to increase with age. Handling procedures used to simulate stress had little effect on thyroxine excretion rate but group penning of pigs temporarily altered thyroxine excretion rate. A diurnal variation in the excretion rate of total and unconjugated thyroxine was observed with peaks about 9.00 h, just before feeding.

Outcome of carcinoma in situ and early invasive carcinoma of the bronchus.

Seventeen patients in whom a squamous carcinoma in situ of the bronchus had been resected have been followed for up to 16 years. The crude mortality rate for these patients is remarkably high, with seven (41%) dead after five years and 14 (82%) after 10 years. Half the patients had died as a direct result of malignant disease by 10 years--because of recurrence, metastatic disease, or the development of a second tumour. A guarded long-term prognosis must be given in these patients owing to the many deaths (mainly from other respiratory diseases) besides those from recurrent cancer.

Calcium-binding activity of rat intestinal mucosa after massive small bowel resection.

Male Sprague-Dawley rats underwent resection of 50 cm of either proximal or distal small intestine or sham-operation. 6-7 weeks after operation mucosal calcium-binding activity was measured in segments of duodenum ileum and remaining 'midgut'. Similar measurements were obtained from weight and age-matched unoperated rats. There was no difference in calcium-binding activity between unoperated and sham-operated animals. After proximal resection the binding activity increased significantly in duodenum and midgut but did not change in ileum. After distal resection the binding activity decreased in duodenum but was unchanged in midgut and ileum. These studies show that mucosal calcium-binding activity undergoes changes but alteration of the binding activity in remaining gut varies with the location of the small bowel resection.