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      Effects of Enhanced External Counterpulsation on Carotid Circulation in Patients with Coronary Artery Disease

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          Background: Enhanced external counterpulsation (EECP) is a noninvasive method previously shown to improve measures of myocardial ischemia in patients with coronary artery disease. However, the concomitant effects of EECP on large and small arterial properties have been poorly examined. In a randomized controlled study, we investigated whether arterial stiffness and resistance of the carotid circulation are altered by EECP. Methods: Thirty patients with angiographically demonstrated coronary artery disease were randomized into two groups to receive either ‘sham’ or active EECP therapy for 35 1-hour sessions. The β stiffness index was calculated by the ln(Ps/Pd)/DD equation where Ps and Pd = systolic and diastolic blood pressure, and DD = the ratio between carotid pulse and diastolic diameter, measured by ultrasound sequential frames during the cardiac cycle. Carotid vascular resistance was calculated as the ratio between mean arterial pressure and mean common carotid blood flow. Results: No significant between-group differences were seen in clinical characteristics or carotid hemodynamics at baseline. The β stiffness index and carotid vascular resistance were significantly reduced after 35 h of active EECP (p < 0.01), and the decrease was significantly different when compared with controls (p < 0.05 for β stiffness index and p < 0.001 for carotid vascular resistance). These reductions persisted after multiple covariate adjustment. Conclusions: This study suggests that EECP exerts clear arterial effects on large and small vessels of the carotid circulation. The combined effects on arterial stiffness and vascular resistance are of particular interest in cardiovascular disease involving reduction in blood flow, in which techniques that increase regional blood flow may be beneficial.

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          Effect of exercise on coronary endothelial function in patients with coronary artery disease.

          Studies of the cardioprotective effects of exercise training in patients with coronary artery disease have yielded contradictory results. Exercise training has been associated with improvement in myocardial perfusion even in patients who have progression of coronary atherosclerosis. We therefore conducted a prospective study of the effect of exercise training on endothelial function in patients with coronary artery disease. We randomly assigned 19 patients with coronary endothelial dysfunction, indicated by abnormal acetylcholine-induced vasoconstriction, to an exercise-training group (10 patients) or a control group (9 patients). To reduce confounding, patients with coronary risk factors that could be influenced by exercise training (such as diabetes, hypertension, hypercholesterolemia, and smoking) were excluded. In an initial study and after four weeks, the changes in vascular diameter in response to the intracoronary infusion of increasing doses of acetylcholine (0.072, 0.72, and 7.2 microg per minute) were assessed. The mean peak flow velocity was measured by Doppler velocimetry, and the diameter of epicardial coronary vessels was measured by quantitative coronary angiography. In the initial study, the two groups had similar vasoconstrictive responses to acetylcholine. After four weeks of exercise training, coronary-artery constriction in response to acetylcholine at a dose of 7.2 microg per minute was reduced by 54 percent (from a mean [+/-SE] decrease in the luminal diameter of 0.41+/-0.05 mm in the initial study to a decrease of 0.19+/-0.07 mm at four weeks; P<0.05 for the comparison with the change in the control group). In the exercise-training group, the increases in mean peak flow velocity in response to 0.072, 0.72, and 7.2 microg of acetylcholine per minute were 12+/-7, 36+/-11, and 78+/-16 percent, respectively, in the initial study. After four weeks of exercise, the increases in response to acetylcholine were 27+/-7, 73+/-19, and 142+/-28 percent (P<0.01 for the comparison with the control group). Coronary blood-flow reserve (the ratio of the mean peak flow velocity after adenosine infusion to the resting velocity) increased by 29 percent after four weeks of exercise (from 2.8+/-0.2 in the initial study to 3.6+/-0.2 after four weeks; P<0.01 for the comparison with the control group). Exercise training improves endothelium-dependent vasodilatation both in epicardial coronary vessels and in resistance vessels in patients with coronary artery disease.
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            An analysis of the relationship between central aortic and peripheral upper limb pressure waves in man.

            Amplification of the pressure pulse between central and peripheral arteries renders pressure values in the upper limb an inaccurate measure of ascending aortic (AA) pressure. Accuracy could be improved by allowance for such amplification. Transfer functions (TF) for pressures between AA and brachial artery (BA):(BATF) and between AA and radial artery (RA):(RATF) were derived from high-fidelity pressure recordings obtained at cardiac catheterization in 14 patients under control conditions, and after sublingual nitroglycerine 0.3 mg. There was no significant difference in BATF under control conditions and with nitroglycerine; hence results were pooled. Control and nitroglycerine results were also pooled to obtain a single RATF. BATF and RATF moduli peaked at 5 Hz and 4 Hz, reaching 2.5 and 2.8 times the value at zero frequency respectively. Frequency-dependent changes in modulus and phase of BATF and RATF were attributable to wave travel and reflection in the upper limb. BATF and RATF were compared to published transfer functions and those derived from analysis of aortic and brachial or radial pressure waves in previous publications. Results were similar. Our BATF and RATF were used to synthesize AA pressure waves from published peripheral pulses. Correspondence was close, especially for systolic pressure which differed by 2.4 +/- 1.0 (mean +/- SEM) mmHg, whereas recorded systolic pressure differed by 20.4 +/- 2.6 (mean +/- SEM) mmHg between central and peripheral sites. Results indicate that in adult humans a single generalized TF can be used with acceptable accuracy to determine central from peripheral pressure under different conditions.(ABSTRACT TRUNCATED AT 250 WORDS)
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              Enhanced external counterpulsation improves endothelial function in patients with symptomatic coronary artery disease.

              The goal of this study was to examine the effect of enhanced external counterpulsation (EECP) on endothelial function. Enhanced external counterpulsation improves symptoms and exercise tolerance in patients with symptomatic coronary artery disease (CAD). However, the exact mechanisms by which this technique exerts its clinical benefit are unclear. Reactive hyperemia-peripheral arterial tonometry (RH-PAT), a noninvasive method to assess peripheral endothelial function by measuring reactive hyperemic response in the finger, was performed in 23 patients with refractory angina undergoing a 35-h course of EECP. In each patient RH-PAT measurements were performed before and after the first, at midcourse, and the last EECP session. In addition, RH-PAT response was assessed one month after completion of EECP therapy; RH-PAT index, a measure of reactive hyperemia, was calculated as the ratio of the digital pulse volume during reactive hyperemia divided by that at rest. Enhanced external counterpulsation led to symptomatic improvement (>/=1 Canadian Cardiovascular Society class) in 17 (74%) patients; EECP was associated with a significant immediate increase in average RH-PAT index after each treatment (p < 0.05). In addition, average RH-PAT index at one-month follow-up was significantly higher than that before EECP therapy (p < 0.05). When patients were divided by their clinical response, RH-PAT index at one-month follow-up increased only in those patients who experienced clinical benefit. Enhanced external counterpulsation enhances peripheral endothelial function with beneficial effects persisting at one-month follow-up in patients with a positive clinical response. This suggests that improvement in endothelial function may contribute to the clinical benefit of EECP in patients with symptomatic CAD.

                Author and article information

                S. Karger AG
                August 2007
                29 September 2006
                : 108
                : 2
                : 104-110
                aCentre de Médecine Préventive Cardiovasculaire, Hôpital Broussais/Hôpital Européen Georges Pompidou, Faculté de Médecine René Descartes Paris 5, bUMR CNRS 7131, cService de Réadaptation Cardiaque, Hôpital Broussais/Hôpital Européen Georges Pompidou, Assistance Publique des Hôpitaux de Paris, Paris, France; dUniversidad Favaloro, Buenos Aires, Argentina
                95949 Cardiology 2007;108:104–110
                © 2007 S. Karger AG, Basel

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                Page count
                Figures: 3, Tables: 2, References: 30, Pages: 7
                Original Research


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