Search PubMed⌕ Search

Biomedical subjects

N L Coplan

Publications and source records attributed to N L Coplan.

At least 37 records · Page 2Linked to original sources
PubMed1991

Gender differences in the systolic blood pressure response to exercise.

Previous work has shown a gender difference in the normal cardiac response to exercise. Men had significantly higher absolute systolic blood pressure responses at 50%, 75%, and 100% peak heart rate on all modalities (p less than 0.05). This difference is absent when systolic blood pressure is adjusted for body surface area, is reduced when adjusted for body weights, and is reversed when systolic blood pressure is adjusted for lean body mass. The influence of gender on the systolic blood pressure response to dynamic exercise was independent of exercise modality. Men had a higher systolic blood pressure in spite of the fact that they had similar sympathetic nervous system response as indicated by urinary norepinephrine excretion. Gender differences in systolic blood pressure responses were altered when adjusted for body weight, body surface area, and lean body mass.

Blood Pressure↗
PubMed1991

Exercise-related atrioventricular block. Influence of myocardial ischemia.

A 62-year-old woman was noted to have complete heart block immediately following an exercise stress test. Coronary arteriography subsequently revealed a significant lesion in the right coronary artery, which was successfully dilated. Thallium-exercise testing following angioplasty showed no evidence of inducible ischemia and no arrhythmia was seen, supporting the idea that exercise-related heart block may occur secondary to myocardial ischemia.

Angioplasty, Balloon, Coronary↗
PubMed1989

Exercise-related changes in serum catecholamines and potassium: effect of sustained exercise above and below lactate threshold.

Plasma potassium and catecholamines exhibit rapid shifts during exercise testing, particularly when exercise intensity exceeds lactate threshold. To assess changes that may occur during sustained exercise, we studied 10 healthy men to determine the effect of 20 minutes of exercise at 25 W above lactate threshold (ALT) and 20 minutes of exercise at 25 W below lactate threshold (BLT). Both conditions showed elevation of catecholamines at end exercise compared to baseline, but catecholamine levels ALT were significantly higher than the levels BLT (2270 +/- 190 versus 900 +/- 230 pg/ml norepinephrine, p less than 0.001; 509 +/- 69 versus 150 +/- 18 pg/ml epinephrine, p less than 0.001). This difference persisted at 2 minutes of recovery (1620 +/- 130 versus 590 +/- 60 pg/ml norepinephrine, p less than 0.001; 216 +/- 31 versus 98 +/- 16 pg/ml epinephrine, p less than 0.001). Both conditions resulted in a significant elevation in potassium at end exercise compared to baseline, but the potassium levels ALT were significantly higher than the levels BLT (1.1 +/- 0.1 mEq/L versus 0.5 +/- 0.1 mEq/L, p less than 0.001. The fall in potassium in the immediate post-exercise period was significantly greater following exercise ALT (-0.8 +/- 0.1 mEq/L versus -0.2 +/- 0.1 mEq/L, p less than 0.001). Thus sustained exercise slightly ALT resulted in a significant potassium flux and very elevated catecholamine levels. Avoiding these metabolic stresses by exercising BLT may decrease chances for exercise-related arrhythmia or other cardiac dysfunction in susceptible patients.

Adult↗
PubMed1987

Comparison of arm and treadmill exercise at 85% predicted maximum heart rate.

Both treadmill exercise and arm exercise are used for evaluating coronary artery disease, but arm exercise has lower diagnostic sensitivity. We compared the two exercise modalities with respect to the rate-pressure product at 85% predicted maximal heart rate, a parameter frequently used to denote performance of sufficient exercise to derive clinical conclusions. At this heart rate, treadmill exercise resulted in a significantly greater systemic oxygen consumption (2.7 +/- .8 vs. 2.1 +/- .6 l/min) and rate-pressure product (30.6 +/- 4.4 X 10(3) vs. 28 +/- 3.3 X 10(3)) than arm ergometry. An inability to generate sufficient imbalance of myocardial oxygen supply and demand may account for the relatively higher incidence of false negative exercise tests seen with arm ergometry, especially if the exercise test is stopped when the patient attains 85% predicted maximal heart rate.

Adult↗
PubMed1987

Doppler echocardiographic analysis of left ventricular filling in treated hypertensive patients.

Early detection and prevention of cardiac dysfunction is an important goal in the management of hypertensive patients. In this study, Doppler echocardiography was used to evaluate the pattern of left ventricular diastolic filling in 38 subjects: 18 treated hypertensive patients (blood pressure 141 +/- 17/83 +/- 10 mm Hg, mean +/- SD) without other coronary risk factors and 20 risk-free normotensive subjects of similar age (47 +/- 10 and 49 +/- 13 years, respectively). Peak velocity of late left ventricular filling due to the atrial contraction was greater in hypertensive compared with normotensive subjects (69 +/- 14 versus 52 +/- 13 cm/s; p less than 0.001). Peak velocity of late filling was significantly greater in hypertensive versus normotensive subjects in those aged 50 years or younger and those older than age 50 (65 +/- 12 versus 50 +/- 11; p less than 0.01 and 75 +/- 15 versus 56 +/- 15 cm/s; p less than 0.05, respectively). In hypertensive subjects, peak velocity of late filling did not correlate with routine indexes of hypertensive heart disease (including posterior wall thickness and left ventricular mass), systolic and diastolic blood pressure or duration of hypertension. These results indicate that increased velocity of late left ventricular filling may be independent of left ventricular hypertrophy and persist despite effective blood pressure control.

Adult↗
PubMed1986

Using exercise respiratory measurements to compare methods of exercise prescription.

Exercise heart rate (HR) ranges based on peak HR, age-predicted maximal HR and peak oxygen consumption were compared to determine which method is most likely to result in an exercise prescription within guidelines determined from exercise respiratory measurements (upper limit--ventilatory threshold; lower limit--50% peak oxygen consumption). Exercise prescriptions based on either 80% peak HR or 70% peak measured oxygen consumption were significantly more likely to be within these guidelines (p less than 0.05) than other criteria tested; there was no significant difference between these 2 methods. Recommended exercise intensity based on 85% peak HR and 80% peak oxygen uptake resulted in a large percentage of patients with a heart rate above the ventilatory threshold (46% and 54%, respectively), whereas target HR derived from 75% peak HR and 60% peak oxygen consumption resulted in many patients with a heart rate below the lower limit (38% and 42%, respectively). Exercise prescription based on predicted maximal HR was of little value, regardless of the percentage used to determine target heart rate. The best methods identified in this study yielded an exercise intensity exceeding ventilatory threshold 15 to 20% of the time. Exercise prescription based on direct assessment of the ventilatory threshold is therefore preferred.

Adult↗
PubMed1986

Principles of exercise prescription for patients with coronary artery disease.

Exercise performance is determined by the interaction of many systems. Cardiac disease, non-cardiovascular pathology, physical training, and the hemodynamic response to the type of exercise the patient wants to perform should all be considered when developing an exercise prescription. There are two stages for deriving a complete exercise prescription, determination of optimal exercise intensity from an exercise test and adoption of the recommendation to include other forms of exercise. The recommendation is usually based on a target oxygen consumption or a target heart rate derived from a treadmill test, but both of these methods may be of limited effectiveness. Ventilatory measurements during exercise, which reflect metabolic changes, are a useful adjunct. The exercise prescription must be individualized to the patient's needs, and may have to be modified so that exercise intensity remains within acceptable limits.

Cardiac Output↗