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Biomedical subjects

C R Conti

Publications and source records attributed to C R Conti.

At least 307 records · Page 17Linked to original sources
PubMed1982

Randomized double-blind comparison of nifedipine and isosorbide dinitrate in patients with coronary arterial spasm.

The effects of nifedinpine and isosorbide dinitrate on the frequency of angina and consumption of nitroglycerin were studied in 19 patients with coronary arterial spasm. After a lead-in phase, the patients were randomized to treatment with either nifedipine or isosorbide dinitrate. After dose titration (40 to 120 mg/day) and evaluation, they were given the alternate therapy. During the initial segment of the double-blind phase, one patient died suddenly (nifedipine phase), one dropped out of the study (nifedipine phase) and another was unable to tolerate therapy (isosorbide dinitrate phase). In the other 16 patients, the mean frequency of angina was less during therapy with both nifedipine (0.69 episode/day, p less than 0.05) and isosorbide dinitrate (0.77 episode/day, p less than 0.05) phases than during the lead-in phase (1.71 episodes/day). The mean frequency of angina was similar in the nifedipine and isosorbide dinitrate phases. A 50 percent or greater decrease in frequency of angina compared with lead-in phase values occurred in 13 of 18 patients during treatment with nifedipine and in 10 of 16 during treatment with isosorbide dinitrate. Of the 16 patients who completed both double-blind phases, 7 showed greater improvement (that is, a 50 percent or greater decrease in frequency of angina) with nifedipine than with isosorbide dinitrate); 6 others showed greater improvement with isosorbide dinitrate, and the other 3 had a less than 50 percent difference in frequency of angina with the two drugs. These findings in a limited number of patients suggest that both nifedipine and isosorbide dinitrate are effective in certain patients with coronary spasm but that neither drug is clearly superior.

Adult↗
PubMed1982

Mexiletine, a new antiarrhythmic agent, for treatment of premature ventricular complexes.

This double-blind crossover study was designed to compare the safety and efficacy or mexiletine, a new class I antiarrhythmic agent, with those of a placebo in reducing premature ventricular complexes. Twelve patients who had a median of 294 such complexes/hour were admitted to the study. Eleven completed 4 weeks of trial with mexiletine and placebo with ambulatory electrocardiographic (Holter) recordings taken at the end of each treatment period. The doses given were designed to reduce the frequency of premature ventricular complexes by 50 percent or more from the baseline value. Mexiletine significantly reduced the rate of premature ventricular complexes by comparison with placebo (-66 percent versus 3 percent, p = 0.032). In addition, mexiletine reduced the median number/hour of ventricular couplets observed. After 4 weeks of therapy, 2, 2, 1 and 6 patients, respectively, were taking 100, 200, 300 and 400 mg of mexiletine every 8 hours. Mexiletine produced no significant change in baseline values including electrocardiographic intervals, blood pressure or heart rate. The most frequently observed adverse effects were digestive difficulties (eight patients taking mexiletine, four taking placebo) and central nervous system effects (seven taking mexiletine, five taking placebo). These data show the efficacy and safety of mexiletine in the treatment of premature ventricular complexes in a majority of patients.

Aged↗
PubMed1982

A mechanical arm for spatial registration of two-dimensional echocardiographic sections.

The accurate calculation of left ventricular (LV) wall motion from two-dimensional echocardiographs will require the accurate registration of the position from which each two-dimensional (2-D) view was obtained. This paper describes a mechanical arm with five degrees of freedom that was developed so that the position and orientation of 2-D echo sections could be calculated in three-dimensional space. High precision potentiometers, direct or gear driven, permit calibration and measurement of each of the five movements. Using the length of the arm and the angles measured by these potentiometers, the position of a 2-D section can be calculated with respect to a fixed reference point outside the body. The measurement arm was extensively retested after six months of clinical use. In patient studies, 95% confidence interval for positioning a cross-section of the long axis is +/- 6 mm. This error is similar to the cross-plane resolution to most contemporary two-dimensional transducers. On the basis of an extensive analysis of variance, recommendations are made to improve the accuracy of the arm.

Echocardiography↗
PubMed1982

Effects of selective injection of contrast media on coronary artery diameter.

The purpose of this study was to quantify the effect of Renografin-76 on epicardial coronary artery diameters, during selective coronary angiography. Using 105 mm-photospot angiograms taken at 0, 1, and 5 min, 99 coronary segments from ten patients were measured. Comparing the angiograms at 1 and 5 min to the control angiograms, a 7 +/- 7% and 6 +/- 7% (both p = NS) change in diameter respectively was noted. Comparing the 1 and 5 min angiograms, there was no significant change (-1 +/- 7%). Measurements were found to be very reproducible. This study shows that there is a trend toward dilation of the coronary arteries during selective coronary angiography, but this did not reach statistical significance and probably is not clinically important.

Adult↗
PubMed1982

Regional coronary artery dilation response in variant angina.

We examined segmental left coronary artery responses to nitroglycerin in 17 variant angina patients and in 34 nonvariant angina patients using a quantitative angiography technique. In those patients with left anterior descending vasospasm, there was a marked exaggeration in the degree of dilation to nitroglycerin in those segments which at other times were involved with spasm. This observation was consistent when these segments were compared to (1) other left coronary segments in the same patient, (2) the same left coronary segments in nonvariant angina patients, and (3) the same left coronary segments in patients with right coronary spasm. These data suggest that a localized disorder in coronary vasomotion is present in patients with coronary spasm that is not limited to constriction but also involves increased dilation in response to nitroglycerin.

Adult↗
PubMed1982

Coronary artery spasm: prevalence, clinical significance, and provocative testing.

Recent clinical and laboratory observations indicate that coronary artery spasm may play a role in the pathophysiology of ischemic heart disease. The majority of patients with ischemic heart disease have coronary atherosclerosis. The prevalence of coronary artery spasm in these patients is unknown. However, current evidence suggests that patients with rest angina have a higher incidence of coronary artery spasm than do patients with reproducible effort angina. Coronary artery spasm may initiate or contribute to acute myocardial infarction, but recent evidence obtained in patients undergoing thrombolytic therapy during the early phases of myocardial infarction suggests that it is not a common occurrence. Although numerous examples of ventricular tachycardia and ventricular fibrillation occur during episodes of coronary artery spasm, the incidence of coronary artery spasm in association with sudden death is unknown. Provocative testing with ergonovine maleate reveals that the highest incidence of provocable coronary artery spasm is found in patients with rest angina. In patients with the syndrome of variant angina, coronary artery spasm is nearly always provocable.

Angina Pectoris↗
PubMed1982

Variability of electrocardiographic responses to repeated ergonovine provocation in variant angina patients with coronary artery spasm.

We reviewed our experience with serial ergonovine provocative tests for coronary artery spasm (CAS) in ten variant angina patients with angiographically proved CAS. Of the 26 ergonovine tests performed in the ten patients, only four patients exhibited reproducible ECG response to ergonovine. The remaining six patients had variable and unpredictable ECG responses to ergonovine. All patients were in an active phase of their disease. The variability of ST segment directional response to ergonovine is considered to be on the basis of disparate sensitivity of the coronary circulation to intravenous ergonovine. Because of this variable response, the ECG response alone should not be considered as the standard indicator for CAS presence but should be utilized with other hemodynamic and angiographic criteria.

Angiography↗
PubMed1982

Effects of carbon dioxide, Nd-YAG, and argon laser radiation on coronary atheromatous plaques.

Laser radiation has been successfully applied in several areas of medical practice. However, its use in cardiology and specifically its effects on obstructive atherosclerosis have largely been unexplored. To evaluate effects of laser radiation on atherosclerotic plaques 25 fresh necropsy atherosclerotic coronary artery segments were exposed to laser radiation with either a carbon dioxide, Nd-YAG, or argon laser. Split or intact segments were prepared under dry conditions or while immersed in saline solution or blood and exposed to laser radiation as power and duration of exposure varied. All 3 lasers were capable of creating controlled injury to atherosclerotic plaques. In general, the magnitude of injury varied according to the total energy delivered (that is, power times duration of exposure. Calcified and noncalcified plaques were penetrated with similar levels of injury. Histologic examination demonstrated that laser radiation produced a wedge incision in the atherosclerotic plaque which was surrounded by zones of thermal and acoustic injury.

Argon↗
PubMed1982

Verapamil therapy for unstable angina pectoris: review of double-blind placebo-controlled randomized clinical trials.

The effectiveness of verapamil in the management of patients with unstable angina pectoris associated with obstructive coronary artery disease was evaluated in 2 double-blind placebo-controlled randomized clinical trials. In the 1st study, verapamil was compared with placebo using alternating 48 hour treatment periods in a multiple cross-over protocol. Verapamil was superior to placebo in abolishing symptomatic and asymptomatic ischemic episodes; there were 127 ischemic events during treatment with placebo but only 27 episodes during therapy with verapamil (p less than 0.006). In the 2nd study, verapamil and placebo were compared using a double-blind randomized parallel design in which the choice of drug was altered and the doses administered were increased according to the individual responses. Verapamil reduced anginal attacks in 12 of 13 patients, but placebo was effective in only 1 of 6 (p less than 0.025); verapamil reduced daily anginal attacks from 3.2 to 0.6/day (p less than 0.01). Thus, verapamil is highly effective in the short-term management of patients with unstable angina secondary to coronary artery disease.

Adult↗
PubMed1982

Regional coronary hemodynamic responses to cold stimulation in patients without variant angina.

The responses to cold in patients with exertional chest pain were studied by measuring coronary sinus and great cardiac vein flows, aortic and left ventricular pressure and diameters of epicardial and small (0.4 to 1.0 mm) intramyocardial coronary arteries before and after the left hand of 18 such patients was immersed in ice water. Coronary sinus and great cardiac vein flows were used as indexes of total and anterior left ventricular flows. Coronary sinus flow minus great cardiac vein flow was used as an index of inferior left ventricular flow. Perfusion of left ventricular regions was considered potentially "normal" or "abnormal" according to the presence or absence of 50 percent or greater stenosis of luminal diameter in the coronary artery supplying a given region. With cold stimulation, increases occurred in heart rate (6 beats/min), mean aortic pressure (22 mm Hg) and left ventricular end-diastolic pressure (8 mm Hg) (all p less than 0.05). Left ventricular flow in normally perfused regions increased as resistance decreased. Left ventricular flow in abnormally perfused regions increased slightly and resistance increased. Regional left ventricular flow increased more, and changes in resistance differed in normally and abnormally perfused regions. Coronary arterial diameter decreased only minimally (6 percent) in both normal and abnormal left ventricular regions. These data show that cold stimulation increases coronary resistance in abnormally perfused left ventricular regions. Cold stimulation-related increases in coronary resistance do not appear to be caused by coronary arterial "spasm."

Adult↗
PubMed1982

Preliminary experience with intraoperative transluminal balloon-catheter dilation and coronary artery bypass grafting for the treatment of symptomatic diffuse coronary artery disease.

Transluminal balloon-catheter dilation of coronary artery lesions has become increasingly common in the cardiac catheterization laboratory. We describe a method of intraoperative dilation that may improve surgical results when used in combination with coronary artery bypass graft (CABG) operations in patients with diffusely diseased coronary arteries. In 16 patients, long-segment intraoperative dilations were performed to enlarge luminal narrowings in 21 different regions. All of these patients had postoperative coronary angiography and left ventriculography so that we could objectively evaluate the coronary dilatations. There were no operative deaths or perioperative myocardial infarctions, and angina was relieved in all patients. Of the 21 dilated segments, 12 (57%) were unchanged, 2 (10%) became worse, and 7 (33%) were improved postoperatively. In addition, two new areas of intimal damage were detected in patients with unchanged postoperative liminal diameters. We conclude that further experience and longer follow-up are necessary before the efficacy of intraoperative coronary artery balloon-catheter dilation can be accurately determined.

Angioplasty, Balloon↗
PubMed1982

Action of intracoronary nitroglycerin in refractory coronary artery spasm.

Coronary artery spasm usually responds to sublingual nitroglycerin. This report describes four patients with variant angina and one patient with rest angina who had coronary spasm that was refractory to sublingual or i.v. nitroglycerin. In four patients, spasm occurred spontaneous and in one patient after 0.05 mg of ergonovine. In each case, 25-100 micrograms of intracoronary nitroglycerin promptly (30-45 seconds) resulted in reopacification of the vessel involved in spasm and resolution of evidence for ischemia. Thus, intracoronary nitroglycerin can reverse coronary artery spasm that does not respond to systemic nitroglycerin administration.

Adult↗
PubMed1982

Analysis of coronary responses to various doses of intracoronary nitroglycerin.

We studied the degree of coronary artery dilation resulting from increasing doses of intracoronary nitroglycerin (NTG). Heart rate, aortic pressure and coronary artery angiograms were recorded before and after 5-, 50-, 150- and 250-microgram doses of NTG infused into the left main coronary artery. Coronary artery diameters were measured by a magnification angiographic technique. After intracoronary NTG, heart rate was unchanged 2 minutes after each dose. Mean aortic pressure was unchanged after 5 microgram (NS), but declined 5 mm Hg (mean) after 50 microgram, 9 mm Hg after 150 microgram and 18 mm Hg after 250 microgram (all p less than 0.05) compared with before NTG. The maximal increase in diameter occurred after 150 microgram, and no additional increase was seen after 250 microgram. After 5- and 50-microgram doses, 67% and 75% maximal dilation responses, respectively, were observed. Compared with coronary artery diameter before NTG, the 150-microgram dose increased the diameter of left main coronary artery by 5%, proximal coronary artery segments by 9%, middle segments by 19%, distal segments by 34%, collateral-filled coronary arteries by 38%, coronary artery stenoses by 5%, and small coronary arteries (0.4-1.0 mm) by 54%. These data indicate that relatively small doses of intracoronary NTG produce potentially important coronary artery dilation without important changes in heart rate and aortic pressure. These observations should prove helpful in choosing dosage schedules for intracoronary NTG.

Aged↗
PubMed1981

Long-term maintenance therapy with prazosin in congestive heart failure.

We evaluated the effects of long-term maintenance therapy with oral prazosin (6-20 mg, mean 14 +/- 2 mg/d) in 14 patients with congestive heart failure. The patients were followed for 6 +/- 1 months. Eleven of the fourteen patients reported subjective improvement. Two patients required increased diuretics because of gain in body weight. Systolic blood pressure showed a slight but sustained decrease suggesting persistent vasodilator effect. Reductions in echocardiographic left ventricular end-diastolic (6.35 +/- 0.25-5.88 +/- 0.25 cm, p less than 0.05) and end-systolic (5.16 +/- 0.35-4.73 +/- 0.28 cm, p less than 0.05) diameters were observed at 2 months. However, the cardiothoracic ratio on chest x ray was unaltered. Maximum exercise tolerance time increased in eight patients (57%) during prazosin therapy. Improvement in exercise tolerance time was observed in patients with most marked clinical improvement, suggesting presence of cardiac reserve. Two patients died suddenly after reporting subjective improvement. This study shows sustained clinical improvement in most patients with heart failure treated with oral prazosin.

Adult↗
PubMed1981

Echocardiographic analysis of systolic and diastolic left ventricular wall motion during transient myocardial ischemia.

Left ventricular (LV) wall motion (anterior and posterior) and simultaneous LV pressure were recorded during 30-second left anterior descending (LAD) or circumflex (CX) coronary artery occlusions in open-chest dogs to provide an echocardiographic model of the evolution of wall motion changes during myocardial ischemia. Prominent diastolic echocardiographic motion changes of progressive decrease in LV wall rapid-filling velocities (RFS), slow-filling velocities (SFS), and increased end-diastolic diameter were accompanied by a marked increase in initial and end-diastolic pressures (150% and 70%, respectively; all p less than 0.05). Early (within ten seconds) and progressive decrease in rat (SES), amplitude (E), and duration (TTR) of systolic motion were noted with an increased systolic diameter (p less than 0.05). Ischemic regions developed a characteristic pattern with early relaxation followed by a diastolic inward motion (DIM). These observations confirm and extend other investigators' findings on the motion of the ischemic myocardium and may be applicable to responses to transient myocardial ischemia noted in humans.

Animals↗