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Biomedical subjects

S N Morris

Publications and source records attributed to S N Morris.

At least 19 recordsLinked to original sources
PubMed1989

Role of pharmacists in reducing occupational exposure to HIV.

The role of pharmacists in reducing the occupational hazard of human immunodeficiency virus (HIV) transmission via needle-stick injuries is described. Some 40% of all pharmaceuticals used in hospitals are now administered by injection, and sales of large-volume injectable drug products continue to grow. Most needle-stick injuries in which health-care workers are exposed to HIV-contaminated blood occur during recapping of used needles, picking up and carrying the needle, or placing it in a receptacle. Pharmacists are responsible not only for the purchase, storage, dispensing, and use of drug products but also for providing information about their administration and safe disposal. Single-use vials, ampuls, and prefilled syringes must all be evaluated for availability, ease of use, and disposal. A major factor in drug-purchasing decisions must be the safety of nurses. Syringes that have been redesigned to eliminate the need for recapping offer a major safety advantage. Needle disposal units should be made more conveniently accessible. Pharmacists can help prevent the transmission of HIV to health-care workers by using their influence as educators and decision makers to reduce the risk of needle-stick injury.

Acquired Immunodeficiency Syndrome↗
PubMed1987

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.

Coronary Disease↗
PubMed1986

Complementary value of two-dimensional exercise echocardiography to routine treadmill exercise testing.

Two-dimensional echocardiograms were done during rest and after exercise in 95 patients who subsequently had coronary arteriography. Prior myocardial infarction was present in 36 patients, 35 of whom had wall motion abnormalities. There was no evidence of prior infarction in 59 patients, 44 of whom had coronary disease. In these 44 patients, the exercise electrocardiogram showed ischemia in 19, was normal in 13, and was nondiagnostic in 12. Exercise echocardiograms were abnormal in 35 of these 44 patients. In 15 patients without coronary disease, the treadmill response was nondiagnostic in 6, ischemic in 1, and normal in 8. Exercise echocardiograms were normal in 13 of these 15 patients. We conclude that exercise echocardiography is a valuable addition to routine treadmill testing. It may be of special value in patients with an abnormal resting electrocardiogram or a nondiagnostic response to treadmill testing or when a false-negative treadmill test is suspected.

Adult↗
PubMed1984

The abnormal exercise electrocardiogram in apparently healthy men: a predictor of angina pectoris as an initial coronary event during long-term follow-up.

A group of 916 apparently healthy men between the ages of 27 and 55 years (mean 37) were followed up with serial medical and exercise test evaluations for a period of 8 to 15 years (mean 12.7) to determine (1) the prevalence and specific types of new coronary events observed in subjects with and without abnormal ST segment responses to exercise and (2) the predictive value of a serial conversion to an abnormal ST segment response to exercise for new coronary events. During the initial evaluation there were 23 subjects (2.5%) with an abnormal ST segment response to exercise. During follow-up there were nine (39%) coronary events in this group: eight cases of angina and one of sudden death. With serial testing, an additional 38 subjects (5.1%) experienced conversion to an abnormal ST segment response to exercise. During follow-up there were 12 (32%) coronary events in this group: 10 cases of angina, one of myocardial infarction, and one other. There were 833 subjects with normal ST segment responses to exercise with all tests. In this group there were 44 (5.3%) coronary events: 25 cases of myocardial infarction, seven of sudden death, and 12 of angina. We conclude that in apparently healthy middle-aged men an abnormal ST segment response to exercise is predictive of angina pectoris but not of myocardial infarction or sudden cardiac death as an initial coronary event.

Adult↗
PubMed1982

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.

Adult↗
PubMed1980

Relation of exercise-induced physiologic S-T segment depression to R wave amplitude in normal subjects.

Exercise electrocardiography was performed in 100 asymptomatic male volunteers with a mean age of 42.6 years. The R wave and total RS amplitude and the magnitude of physiologic S-T segment depression at the J junction were quantitated for a modified bipolar CC5 lead and a vertically oriented bipolar lead (VL) using computer-averaged groups of 25 consecutive QRS complexes from each of seven stages of rest and exercise. Computer-generated X-Y plots were used to examine the correlations between the magnitude of S-T depression and the R wave and total RS amplitudes. The magnitude of S-T depression and of the R wave amplitude were unrelated at standing rest but showed increasing correlation with progressive increases in exercise heart rate (correlation coefficient = 0.425, p < 0.00001 at maximal exercise). The total RS amplitude was also related to the magnitude of S-T depression during exercise, but the correlations did not improve progressively with increases in exercise heart rate. The magnitude of S-T depression was more closely related to R wave amplitude and total RS amplitude in the vertically oriented lead than in the CC5 lead. These data demonstrate a significant relation between the magnitude of R wave and total RS amplitudes and the magnitude of physiologic S-T segment depression in normal subjects during exercise. They suggest the need for evaluation of S-T depression corrected for R wave amplitude in an attempt to improve the diagnostic accuracy of the exercise electrocardiogram. The data also suggest that the criteria for abnormal S-T depression should take into consideration the different R wave voltages reflected by different types of recording leads.

Adult↗
PubMed1979

Noninvasive documentation of Prinzmetal's angina.

A 57 year old women with substernal nonexertional chest pain and angiographically patent coronary arteries was evaluated with two dimensional echocardiography and myocardial perfusion scintigraphy after provocation of pain with methacholine. Simultaneous with the development of angina pectoris, the electrocardiogram demonstrated S-T segment elevation in leads II, III and aVF, followed by atrioventricular block. The echocardiogram revealed akinesia of the previously normally contracting left ventricular posterior wall during pain followed by hyperkinesia after the administration of nitroglycerin. Perfusion imaging suggested reversible inferior wall hypoperfusion. Thus, these studies provided noninvasive documentation of segmental left ventricular dysfunction and hypoperfusion during variant angina.

Angina Pectoris↗
PubMed1979

Exercise-induced U-wave inversion as a marker of stenosis of the left anterior descending coronary artery.

The prevalence and cineangiographic correlates of exercise-induced inversion of U waves were studied in 248 patients. Exercise-induced U-wave inversion was observed in 36 patients (15%), of whom 35 had greater than or equal to 75% stenosis in one or more of the major coronary arteries. The proximal left anterior descending or left main coronary artery was involved in 33 of these patients, including 24 patients with no electrocardiographic evidence of anterior myocardial infarction. Exercise-induced U-wave inversion was observed in the absence of an abnormal resting 12-lead ECG. Only one of the 82 patients (1.2%) without significant coronary artery disease demonstrated exercise-induced U-wave inversion, and this patient had a primary cardiomyopathy. We conclude that exercise-induced inversion of the U-wave is highly predictiveof significant coronary artery disease and, more specifically, of disease of the proximal left anterior descending coronary artery.

Adult↗
PubMed1978

Role of exercise stress testing in healthy subjects and patients with coronary heart disease. Controversies in cardiology--I.

The value of the exercise stress test in the evaluation of clinically healthy subjects and patients with coronary heart disease is not limited to the isolated interpretation of abnormalities of the S-T segment. Other measurable parameters which are of diagnostic and prognostic importance include: (1) a decrease in systolic blood pressure during exercise; (2) the appearance of complex ventricular arrhythmias of low exercise heart rates; (3) the appearance of inverted U waves during or after exercise; (4) the patient's maximal exercise capacity; and (5) new auscultatory findings postexercise. The reliability of the exercise test as a diagnostic tool is futher enhanced by proper patient selection and careful attention to exercise techniques. Subjects with labile ST-T wave changes during standing hyperventilation, fixed ST-T changes at rest, and intraventricular conduction defects are not ideal candidates for "diagnostic" stress testing and the examining physician must rely more heavily on nonelectrocardiographic findings. The criteria used to define an abnormal S-T response will vary according to the lead system used. However, in both symptomatic and asymptomatic subjects the appearance of marked degrees of S-T depression at low exercise heart rates significantly increases the probability of finding advanced coronary disease, particularly if the S-T depression is seen in multiple monitoring leads and is of prolonged duration postexercise.

Adult↗
PubMed1977

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.

Adult↗
PubMed1976

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.

Adult↗