Distensibility of the Ascending Aorta in Coronary Artery Disease and Changes After Nifedipine Administration* Christodoulos Stefanadis, M.D.; Costas Stratos, M.D.; Harisios Boudoulas, M.D.; Charalambos Vlachopoulos, M.D.; Joannis Kallikazaros, M.D.; and Pavlos Toutouzas, M.D. To study the effect of nifedipine on aortic distensi- bility in patients with coronary artery disease, as- cending aorta distensibility was measured before and 10 min after 10 mg of nifedipine was given sublingually in 13 patients with coronary artery disease and 12 control subjects. Aortic distensibility was calculated as a function of changes in the aortic diameter and pulse pressure. Aortic diameters were measured by echocardiography and aortic pres- sures were measured directly by catheterization of the ascending aorta. At baseline, aortic distensibil- ity was lower in patients with coronary artery dis- I t is well appreciated today that functional prop- erties of large arteries are important not only for the normal function of the artery itself, but also for left ventricular function as well, since ventricu- lar-vascular coupling mismatch may result in reduc- tion of ventricular performance. l Previous studies from our laboratory2-4 and otherS- 7 laboratories have shown that distensibility of the ascending aorta is decreased in the presence of coronary artery disease. Other studies have also shown that calcium channel blockers have a direct action on the vascular system, decreasing smooth muscle tone not only in the peripheral arterial walls, but also in the aortic wall. s Indeed, nifedipine improves the distensibility of the descending aorta in experimental animals 9 and the distensibility of the ascending aorta in hypertensive patients. lo The effect of the calcium channel blockers on the distensibility of the ascending aorta in patients with coronary artery disease has not been studied (to our knowledge). This investigation was undertaken to study the effect of nifedipine on the distensibility of the ascending aorta in patients with coronary artery disease. *From the Department of Cardiology, University of Athens Medical School, Hippokration Hospital, Athens, Greece (Drs. Stefanadis, Stratos, Vlachopoulos, Kallikazaros, and Toutouzas), and the Ohio State University, Division of Cardiology, Colum- bus, Ohio (Dr. Boudoulas). This work was supported by a grant from the Hellenic Heart Foundation. Manuscript received May 27, 1993; revision accepted October 13 Reprint requests: Dr. Stefanadis, 9 Tepeleniou str, Paleo Psy- chico, Athens 15452, Greece ease compared with control (0.922 ± 0.367 vs 2.456±O.588 lO-6. cm2.dyn-l, respectively, p<O.OOl). After nifedipine administration, aortic distensibility increased significantly both in normal subjects (by 0.812 ± 0.316 em!. dyn- 1 -36.5 ± 19 percent; p<O.OOI) and in patients with coronary artery dis- ease (by O.296±0.203 10-6. cm2.dyn-l_36.6±28.2 percent; p<O.OOI). These results indicate that nifedipine administration increases aortic distensi- bility in both normal subjects and patients with coronary artery disease. (Chest 1994; .105:1017-28) METHODS Study Population Eighty-two consecutive male patients, with an age range from 40 to 50 years, who had undergone diagnostic cardiac catheterization for evaluation of chest pain were selected as potential subjects for the study. Patients with arterial hyperten- sion (systolic arterial pressure mm Hg and/or diastolic arterial pressure mm Hg), valvular heart disease, history of previous myocardial infarction, congenital heart disease, dilated cardiomyopathy, ejection fraction <58 percent (value corre- sponding to the lower 95 percent confidence limits of the ejection fraction of the male subjects, aged 40 to 50 years old, who undergo diagnostic catheterization in our institution for evaluation of chest pain and are found to have normal coronary arteries), chronic obstructive pulmonary disease, history of cerebrovascular accident, and diabetes mellitus were excluded prior to entry into the study. With these criteria, 28 of the initial 82 patients were selected. In addition, three more patients with technically less than optimal echocardiograms were excluded from further analyses. The remaining 25 patients were divided into two groups according to the angiographic result. Thirteen patients had coronary artery disease (luminal stenosis per- cent in diameter) in at least one of the major coronary arteries. Twelve patients with entirely normal coronary arteries were used as normal controls (patients with plaque disease, namely patients with coronary atherosclerotic lesions causing luminal stenosis <50 percent in diameter, were also excluded). Treat- ment with all medications except aspirin was discontinued at least five half-lives before the study. All subjects had normal serum electrolytes and normal results of kidney and liver functional tests. The study protocol was approved by the institution committee on human research of our hospital and informed consent was obtained from each subject after detailed descriIr tion of the procedure. A 6-French fluid-filled pigtail catheter was introduced by a percutaneous technique via the right femoral artery and its tip was positioned under fluoroscopy in the ascending aorta. After 30 min rest in the supine position, echocardiograms and aortic pressures were recorded simultaneously before and 10 min after CHEST /105/4/ APRIL, 1994 1017