Electrocardiographic monitoring during cardiac rehabilitation.

STUDY OBJECTIVE: This investigation compares the frequency of cardiac events during ECG-monitored cardiac rehabilitation in patients who meet the American College of Cardiology (ACC) criteria for monitoring, to the frequency of events in patients in the same program who do not meet the ACC criteria. DESIGN AND PATIENTS: Patient charts (n = 289) from a 10-month period were retrospectively reviewed for (1) major and minor cardiovascular events, (2) whether a physician was contacted, and (3) what change, if any, was made in their care plan as a result. RESULTS: There were no sudden deaths, fatal or nonfatal myocardial infarctions, or sustained arrhythmias requiring hospitalizations. The overall rate for minor events (angina, nonsustained arrhythmia, ST segment depression) was 26.6%, with no difference noted between men and women. The rate for a new-onset, asymptomatic event was 3.8%. The rate of minor events was greater in patients who met the ACC criteria vs those who did not (p < 0.01), with no detectable difference noted between the two groups regarding the rate of new-onset, asymptomatic events. Four patients (1.4%) experienced a change in their care plan as a result of ECG monitoring. CONCLUSIONS: The occurrence of a minor cardiovascular event is common during phase 2 cardiac rehabilitation, and existing criteria satisfactorily distinguish those patients at high risk for experiencing such an event. However, the rate for new-onset, asymptomatic events is rare for both patients classified at high risk and those classified not to be at high risk. Also, only four patients experienced a change in therapy secondary to an event identified by ECG monitoring.

Cardiorespiratory responses during exercise in competitive in-line skaters.

This study describes the cardiorespiratory responses of 12 male (age = 30 +/- 6 yr) competitive in-line skaters during peak and submaximal skating. We hypothesized that velocities of 22.5 and 27.4 km.h-1 would elicit heart rate (HR) and oxygen consumption (VO2) responses consistent with the American College of Sports Medicine's guidelines for developing cardiorespiratory fitness. Using a 644-m indoor cement course, subjects completed 10 trials comprised of various velocities, stroke frequencies, and body positions. At 22.5 km.h-1, HR and VO2 were 74 and 51% of peak, respectively. At 27.4 km.hr-1, HR and VO2 were 85 and 72% of peak, respectively. When compared to the College's guidelines, regression analysis revealed a leftward shift in the VO2-HR relationship, evidenced by a disproportionately higher HR at a VO2 approximating 60 vs 80% of peak. At 22.5 km.h-1 our skaters self-selected a stroke frequency which resulted in less of an increase in both HR and VO2, when compared to the imposed stroke frequencies of 50 min-1 and 70 min-1. Also, skating at 27.4 km.h-1 in the bent vs upright position resulted in less of an increase in HR and VO2. Competitive in-line skaters are capable of safely skating at velocities sufficient to stimulate an increase in cardiorespiratory fitness. These athletes select a stroke frequency and utilize a body position which results in favorable HR and VO2 responses.

Exercise training in a patient with congestive heart failure on continuous dobutamine.

We present a 53-yr-old man with congestive heart failure who underwent 32 wk of exercise training. The patient was on a continuous infusion of dobutamine for 10 months prior to exercise training, which was subsequently discontinued at wk 24 of exercise training. Symptom-limited graded exercise tests were performed at baseline, wk 12, wk 24, and wk 32 of exercise training. While on a continuous infusion of dobutamine, the patient's oxygen consumption and exercise duration were increased during the exercise training period. Additionally, the patient was able to maintain these changes for 8 wk while continuing to exercise after the discontinuation of the dobutamine therapy.

Assessment of body composition in heart transplant patients.

Orthotopic heart transplantation (OHT) recipients often experience increased body weight (BW) following surgery. Using hydrostatic weighing (HW), this study assessed the body density (BD) and body composition of 17 white and seven black male OHT patients. It examined the cross-validity of the Jackson and Pollock seven and three site skinfold (SF) regression equations for predicting BD in these patients. We hypothesized that both prednisone (P) dose and months post-operative (MPO) would be inversely related to BD. The average of the last five of ten HW trials was used in computing BD. BW and % body fat (BF) were 88.5 +/- 17.8 kg (mean +/- SD) and 33.5 +/- 9.4%, respectively. The correlation coefficient between hydrostatically determined BD and BD determined via two of the three intercept revised Jackson and Pollock SF equations was r = 0.89, SE = 0.009. A polynomial regression model for BD using P dose and MPO provided a correlation coefficient of r = 0.71, SE = 0.015. Partial correlation techniques incorporating SF, age, MPO, and P dose indicated that neither P dose or MPO provided any significant additive effect, above SF and age, when predicting BD. We conclude that in OHT patients receiving glucocorticoids, the intercept revised Jackson and Pollock SF regression equations are generally applicable and associated with a SE of +/- 4 BF percentage points. Up to 49 months after OHT, both P dose and MPO are inversely related to BD but provide no additive value above SF for predicting BD.