Acute coronary thrombotic occlusion following exercise testing 6 weeks after percutaneous transluminal coronary angioplasty.

Exercise stress testing is often performed following percutaneous transluminal coronary angioplasty (PTCA) in order to evaluate the efficacy of the procedure. Together with thallium-201 (Tl-201) scintigraphy, these noninvasive tests provide valuable data for predicting the recurrence of angina and restenosis. However, concerns regarding the safe timing of exercise testing post-PTCA have been raised in 3 previous case reports. Each case documents acute coronary occlusion shortly after stress testing performed within several days of successful angioplasty, leading to the recommendation that such testing be deferred up to 4 weeks following PTCA. This paper reports a patient in whom acute thrombotic occlusion of the left anterior descending coronary artery (LAD) occurred immediately after a mildly abnormal exercise Tl-201 stress test done 6 weeks after PTCA.

Impaired cardiopulmonary response to exercise in moderate hypertension.

OBJECTIVE: To identify the limiting factors of exercise performance in subjects with hypertension associated with left ventricular hypertrophy. The secondary objective was to establish relationship between peripheral function and exercise capacity. DESIGN: Cardiopulmonary exercise testing was conducted using two protocols: a graded exercise test to maximal effort established maximal exercise capacity, followed by a step-incremental test combining gas-exchange measures and radionuclide angiography. The exercise responses were compared within and between groups. SETTING: All hypertensive subjects were selected from the Toronto Tri-Hospital Hypertension Clinic. Normal subjects were recruited from the surrounding community. PATIENTS: Twelve patients with established hypertension and left ventricular hypertrophy (determined by echocardiography) were studied as a referred/volunteer sample. All had no evidence of coincident diseases and were unmedicated at time of testing. A volunteer sample of normal, healthy subjects acted as a control. INTERVENTIONS: Graded exercise to maximum and step-incremental (submaximal and steady-state) exercise was used to quantify cardiopulmonary function during exercise stress. MAIN OUTCOME MEASURES: These included (for exercise performance) maximal oxygen intake (VO2max), the ventilatory anaerobic threshold, total peripheral resistance and blood lactate. Cardiac function measures included ejection fraction and ventricular volumes. RESULTS: Cardiac function data obtained during exercise in hypertensive subjects included an increase in the pressure to volume ratio, but a blunted ejection fraction response at peak exercise (P less than 0.05). Although end-diastolic volume increased during exercise (P less than 0.05), values were lower during both levels of exercise compared with normal subjects. Mean +/- SD end-systolic volume increased from 39 +/- 22 at rest to 42 +/- 23 mL during peak exercise. Hypertensive subjects had a lower VO2 max (mean 27.4 +/- 4.8 mL/kg/min) compared with normals (40.0 +/- 8.5 mL/kg/min) and a lower ventilatory anaerobic threshold (14.4 +/- 2.9 versus 27.6 +/- 5.8 mL/kg/min, P less than 0.005). Furthermore, hypertensive patients had a significantly elevated total peripheral resistance at rest (2.5 +/- 1.0 versus 1.8 +/- 0.4 peripheral resistance units) and at peak exercise (1.6 +/- 0.7 versus 0.8 +/- 0.2, P less than 0.01) compared with normal subjects (P less than 0.05). A correlation coefficient of 0.92 was found between total peripheral resistance and VO2 max in hypertensive subjects (P less than 0.01). CONCLUSIONS: These data suggest that peripheral factors, specifically a failure to reduce significantly total peripheral resistance, limits exercise performance despite a maintenance of left ventricular function during exercise in patients with moderate hypertension. The use of cardiopulmonary exercise testing can help in identifying the underlying cause of exercise intolerance in this population and limited left ventricular reserve at peak exercise, and may offer a sensitive measure of therapeutic end-points.

Cardiac output response to continuous positive airway pressure in congestive heart failure.

The effects of nasal continuous positive airway pressure (CPAP) were examined during cardiac catheterization in 22 patients with congestive heart failure (CHF). CPAP was applied at a level of 5 cm H2O pressure. Hemodynamic measurements were made at baseline and while on CPAP. We hypothesized that patients with high left ventricular (LV) diastolic pressures would experience an increase in cardiac index (CI). To test this hypothesis, patients were divided into two groups based on their baseline pulmonary capillary wedge pressure (PCWP): one group of 11 whose PCWP was greater than or equal to 12 mm Hg (high-PCWP group) and a second group of 11 whose PCWP was less than 12 mm Hg (low-PCWP group). Among the high-PCWP group (mean PCWP +/- SEM = 19.0 +/- 2.7 mm Hg), CI rose significantly while on CPAP (from 2.48 +/- 0.26 to 2.82 +/- 0.26 L/min/m2, p less than 0.01). Stroke volume index (SVI) also rose significantly (from 52.6 +/- 7.0 to 64.1 +/- 8.0 ml/m2, p less than 0.001). In contrast, among the low-PCWP group (PCWP = 8.3 +/- 0.6 mm Hg), CI decreased significantly while on CPAP (from 3.14 +/- 0.44 to 2.89 +/- 0.62 ml/m2, p less than 0.025). SVI fell but not significantly while on CPAP (from 75.5 +/- 8.4 to 74.2 +/- 8.5 ml/m2). Multiple stepwise linear regression analysis revealed that the only significant correlate of the magnitude of change in CI in response to CPAP was baseline PCWP (r = 0.50, p less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)