Increased response of diastolic blood pressure to exercise in patients with coronary artery disease: an index of latent ventricular dysfunction?

The effect of different doses of aerobic exercise training on exercise blood pressure in overweight and obese postmenopausal women

OBJECTIVE

Abnormally elevated exercise blood pressure is associated with an increased risk of cardiovascular disease. Aerobic exercise training has been shown to reduce exercise blood pressure. However, it is unknown whether these improvements occur in a dose-dependent manner. The purpose of the present study was to determine the effect of different doses of aerobic exercise training on exercise blood pressure in obese postmenopausal women.

METHODS

Participants (N = 404) were randomized to one of four groups--groups with 4, 8, or 12 kcal/kg of energy expenditure per week or a nonexercise control group--for 6 months. Exercise blood pressure was obtained during the 50-watt stage of a cycle ergometer maximal exercise test.

RESULTS

There was a significant reduction in systolic blood pressure at 50 watts in the 4 kcal/kg per week (-10.9 mm Hg, P < 0.001), 8 kcal/kg per week (-9.9 mm Hg, P = 0.022), and 12 kcal/kg per week (-13.7 mm Hg, P < 0.001) compared with control (-4.2 mm Hg). Only the highest exercise training dose significantly reduced diastolic blood pressure (-4.3 mm Hg, P = 0.033) compared with control. In addition, resting blood pressure was not altered after exercise training (P > 0.05) compared with control and was not associated with changes in exercise systolic (r = 0.09, P = 0.09) or diastolic (r = 0.10, P = 0.08) blood pressure.

CONCLUSIONS

Aerobic exercise training reduces exercise blood pressure and may be more modifiable than changes in resting blood pressure. A high dose of aerobic exercise is recommended to successfully reduce both exercise systolic and diastolic blood pressure and therefore may attenuate the cardiovascular disease risk associated with abnormally elevated exercise blood pressure.

Hemodynamic, hemostatic, and endothelial reactions to psychological and physical stress in coronary artery disease patients

Episodes of psychological and physical stress may elicit thrombotic cardiac events, such as myocardial infarction. These events are triggered when there are concurrent hemodynamic, hemostatic, and endothelial abnormalities. Hemodynamic, hemostatic, and endothelial reactions of 72 (15 women, 57 men) coronary artery disease patients to psychological and physical stress were examined. Blood pressure, electrocardiography, and impedance cardiography were recorded during rest, mental arithmetic, and exercise. Blood was collected, via catheter, at rest and after each task. Mental arithmetic elicited increases in blood pressure, heart rate, cardiac output, and cardiac contractility, but no consistent changes in hemostatic and endothelial markers. In contrast, exercise, in addition to increasing blood pressure, heart rate, cardiac output, cardiac contractility, and lowering peripheral resistance, elicited increases in plasma viscosity, hematocrit, platelets, and tissue plasminogen activator together with a decrease in plasminogen activator inhibitor. This pattern of hemodynamic, hemostatic, and endothelial reactions suggests that acute psychological and physical stress influence the thrombotic system differently in these high risk patients. Future research is needed to investigate how these stress responses are prospectively related to acute cardiac events.

Exercise for patients with congestive heart failure

Congestive heart failure is a widely prevalent sequel to myocardial infarction and other chronic conditions (including ischaemia without infarction, hypertension, various infections, toxic metabolic and endocrine disorders). Exercise tolerance is severely limited; the cardiac ejection fraction is often less than 20% and the peak oxygen intake may be less than 10 ml/kg x min, with a resulting deterioration in the quality of life. Possible factors contributing to the poor tolerance of exercise include: (i) disturbances of myocardial function (damage to the ventricular wall; decreased inotropic response, mitral valve regurgitation and increased diastolic pressures); (ii) peripheral vascular factors (decreased metaboreceptor discharge, reduced vasodilator response, increased activity of sympathetic afferents and less efficient distribution of cardiac output); (iii) hormonal disturbances (increases of catecholamines, renin/angiotensin/aldosterone, antidiuretic and natriuretic factors, endothelin and decreased endothelium-relaxing factor); (iv) impaired muscle function (loss of lean tissue, increase of type II fibres, increased impedance to perfusion, enzyme changes); (v) ventilatory disturbances (increased oxygen cost of activity, pulmonary congestion, increased ventilatory drive, mismatching of ventilation and perfusion, increased anaerobic effort); and (vi) psychological factors (anxiety, depression and iatrogenic limitation of effort). The prognosis with conventional treatment is poor, but patients with stable congestive heart failure respond favourably to a progressive exercise programme. Reported gains depend on the cause of congestive failure, initial status, study duration and compliance, and the type of training programme. Most studies to date have been short term (4 to 16 weeks), and relatively few have adopted a randomised controlled design. Suggested bases for the enhancement of aerobic performance of up to 20% include an increased intensity of peak effort, an enhanced matching of ventilation to perfusion, improved cardiac function, a strengthening of skeletal muscle and an increase of aerobic enzyme activity in the muscles. A few studies have continued for a year or longer and it appears that the gains realised over the first 16 weeks of training can be sustained for this period; the quality of life is enhanced, but data are as yet insufficient to judge effects upon mortality rates. Useful clinical information can be obtained from a 6-minute walk, but the choice for more precise evaluation lies between a measurement of ventilatory threshold or peak oxygen intake. Given initial muscle wasting, prescribed exercise should include both aerobic activity and resisted muscle exercises.

Diastolic aortic pressure rise during percutaneous transluminal coronary angioplasty: an index of left ventricular systolic dysfunction

OBJECTIVES

To investigate the relation between diastolic aortic pressure response and left ventricular systolic dysfunction during percutaneous transluminal coronary angioplasty.

BACKGROUND

The abnormal diastolic blood pressure rise during exercise in patients with coronary artery disease probably reflects left ventricular systolic dysfunction rather than the number of stenosed coronary arteries.

METHODS

Aortic blood pressures and left ventricular systolic function indices were estimated in 26 patients with single proximal stenosis of the left anterior descending coronary artery both before and during angioplasty.

RESULTS

During coronary angioplasty all patients presented an increase in diastolic aortic pressure (P << 0.001), 8-12s before intracoronary electrocardiographic changes. During acute ischaemia there was a decrease in left ventricular ejection fraction (P << 0.001) and stroke volume (P << 0.001) and an increase in end systolic volume (P << 0.001) and left ventricular end diastolic pressure (P << 0.001). No statistically significant changes were observed in systolic blood pressure or heart rate. The aortic diastolic pressure increase was correlated with the decrease in ejection fraction (r = -0.95, P << 0.001) and with the increases in end systolic volume (r = 0.86, P << 0.001) and left ventricular end diastolic pressure (r = 0.85, P << 0.001).

CONCLUSIONS

The rise in diastolic aortic pressure during percutaneous transluminal coronary angioplasty occurs earlier than intracoronary electrocardiographic changes and is related to ischaemic left ventricular systolic dysfunction.

Short-term effects of right atrial, right ventricular apical, and atrioventricular sequential pacing on myocardial oxygen consumption and cardiac efficiency in patients with coronary artery disease

OBJECTIVE

To investigate the short-term effects of atrial, atrioventricular, and ventricular pacing on myocardial oxygen consumption, myocardial blood flow, and cardiac efficiency in patients with coronary artery disease.

DESIGN

Prospective study that started at the end of diagnostic coronary angiography in 13 patients and was performed during atrial, atrioventricular, and ventricular pacing for 5 min, in random order, at 20 beats/min more than the heart rate of the patient's positive exercise test. A Baim thermodilution catheter in the coronary sinus was used to measure myocardial blood flow and oxygen consumption and a pacing electrode at the right ventricular apex and a catheter in the pulmonary artery were used to estimate cardiac output.

SETTING

Referral cardiology centre.

PATIENTS

13 patients with coronary artery disease (mean (SD) age 53(5) years). All the patients had a positive exercise test and most of them (77%) had left anterior descending coronary artery disease.

RESULTS

Mean (SD) cardiac output increased by 0.5(1.6) l/min during atrial pacing, increased by 0.1(1) l/min during atrioventricular pacing, and decreased by 0.8(1.2) l/min during ventricular pacing (P = 0.01 v atrial pacing, P = 0.03 v atrioventricular pacing). Diastolic pulmonary pressure increased by 6(4) mm Hg during atrial pacing, by 8.6(4) mm Hg during ventricular pacing (P = 0.02 v atrial pacing), and by 7.5(4.7) mm Hg during atrioventricular pacing. Changes in myocardial oxygen consumption and cardiac efficiency during the different pacing modes were similar.

CONCLUSION

Atrial, atrioventricular, and ventricular pacing had similar short-term effects on myocardial oxygen consumption, myocardial blood flow, and cardiac efficiency in patients with coronary artery disease. Ventricular pacing, however, did not increase cardiac output.