Biomedical subjects

C C de Cock

Publications and source records attributed to C C de Cock.

27 records · Page 2Linked to original sources

PubMed1994

Influence of pacing-induced myocardial ischemia on left atrial regurgitant jet: a transesophageal echocardiographic study.

OBJECTIVES: We investigated the influence of pacing-induced myocardial ischemia on systolic regurgitant jet in the left atrium, using simultaneous transesophageal echocardiography and transesophageal atrial pacing. BACKGROUND: In vitro studies have shown that ischemia-induced mitral regurgitation may occur as a result of mitral leaflet malcoaptation or (global) left ventricular dysfunction. However, no transesophageal echocardiographic study has thus far been performed to demonstrate the mechanism and extent of mitral regurgitation during myocardial ischemia in patients. METHODS: In 24 patients (mean [+/- SD] age 57 +/- 10 years) with (15 patients) and without (9 control subjects) coronary artery disease, heart rate, blood pressure and systolic regurgitant jet were assessed before and immediately after pacing. Pacing was increased stepwise up to 160 beats/min to provoke wall motion abnormalities while the left ventricular short axis was monitored at the midpapillary muscle level. Other variables obtained before and at peak pacing included left ventricular end-diastolic and end-systolic areas and left ventricular end-diastolic and end-systolic endocardial segmental lengths. RESULTS: Heart rate and blood pressure before and after pacing were not significantly different in control subjects or in patients. At baseline, a jet was present in all but three control subjects. New or increased anterior or posterior wall motion abnormalities were observed during pacing in seven and eight patients, respectively. End-systolic left ventricular areas and segment lengths were significantly reduced in control subjects compared with patients with coronary artery disease at peak pacing (p < 0.05). The increase in systolic regurgitant jet was significantly greater in patients (2.0 +/- 1.1 to 3.1 +/- 1.8 cm2 vs. 0.7 +/- 0.7 to 0.9 +/- 0.9 cm2 [after pacing], p < 0.01). This effect was greater in patients with posterior than with anterior wall motion abnormalities (3.5 +/- 1.6 vs. 2.1 +/- 1.2 cm2 [after pacing], p < 0.05). CONCLUSIONS: Quantitative changes in geometry and function of the left ventricle caused by pacing-induced myocardial ischemia augments systolic regurgitant jet size. An increase in the jet during atrial pacing is associated with new or increased wall motion abnormalities, especially of the posterior wall. Pacing-induced anterior wall motion abnormalities appear not to be related directly to an increase in the jet.

Blood Pressure↗

PubMed1992

Identifying patients for rate responsive atrial pacing: a new method for patient selection and pacemaker programming.

In patients with sinus node disease (SND) and chronotropic incompetence, atrial rate adaptive stimulation (AAI,R pacing) is regarded as the most appropriate pacing mode. Since coronary artery disease is the most common etiology in these patients, we evaluated a new technique combining two-dimensional transesophageal echocardiography and atrial transesophageal pacing to detect pacing induced wall motion abnormalities and assess safe upper rate limits. Thirty-five patients were studied: 26 with and 9 without angiographic coronary artery disease. Stable atrial capture was achieved in all patients using 12 +/- 3 msec pulse width and 12 +/- 4 mA current strength. Sensitivity and specificity for the detection of coronary artery disease was highest for transesophageal echocardiography during pacing (sensitivity 81%, specificity 100%). Simultaneous 12-lead ECG during pacing had lower values (sensitivity 57%, specificity 75%). Pacing induced wall motion abnormalities preceded ST segment changes in all patients. Exercise stress testing showed similar values (sensitivity 62%, specificity 89%). It is concluded that simultaneous transesophageal echocardiography and transesophageal pacing is a safe and useful technique in selecting patients for AAI,R pacing and for the detection of safe upper rate limits, particularly when coronary artery disease is suspected.

Algorithms↗

PubMed1992

Prognostic value of thallium-201 exercise scintigraphy in low-risk patients after Q-wave myocardial infarction: comparison with exercise testing and catheterization.

In a prospective study of 100 consecutive patients discharged after a Q-wave myocardial infarction, the value of reversible ischemia on thallium-201 scintigraphy to assess the risk of cardiac events (death or reinfarction) during 4 years was compared with variables from exercise testing and cardiac catheterization. Patients with markedly impaired left ventricular function [ejection fraction (EF) < or = 0.30] were excluded. During follow-up there were 20 cardiac events (10 cardiac deaths and 10 reinfarctions). Thallium-201 scintigraphy was significantly better than all exercise test variables and better than an EF < 0.40, with good sensitivity and specificity (75 and 51%, respectively). Exercise-induced reversible ischemia on scintigraphy yielded the same information as the presence of multivessel disease. Exercise test variables were of limited value to assess prognosis. Thus, thallium-201 scintigraphy can be used as the only tool to predict future cardiac events in low-risk patients after a Q-wave myocardial infarction.

Adult↗

PubMed1991

Effects of nisoldipine on systolic and diastolic function in postinfarction patients with reduced left ventricular function: a randomized, double-blind, placebo controlled study.

The long-term effects of oral nisoldipine or placebo on clinical variables, exercise test results and echo Doppler-determined systolic and diastolic functions were studied in 30 consecutive patients with reduced left ventricular function (predischarge echocardiographic wall motion score greater than or equal to 8) following myocardial infarction. Groups were comparable in clinical variables, exercise results, echo Doppler measurements and coronary anatomy. During 6 months follow-up, death, reinfarction and bypass surgery or balloon angioplasty were equally distributed. A significant increase in exercise duration and time to onset of ST-depression was found in the nisoldipine treatment group, compared to the placebo group after 3 and 6 months. Time to onset of angina was not significantly different. Echocardiographic indices of left ventricular systolic function (ejection fraction and wall motion score) were unaltered; however, the time-velocity integral of the early diastolic filling phase and the early vs late diastolic flow velocity ratio were significantly increased while the atrial time-velocity integral vs total time-velocity integral was significantly decreased in the nisoldipine treatment group after 3 and 6 months of follow-up. In conclusion, nisoldipine reduced exercise-induced ischaemia, improved exercise capacity and diastolic left ventricular function in postinfarction patients with reduced left ventricular function.

Cardiac Catheterization↗

PubMed1991

Independent prognostic value of supraventricular arrhythmias on 24-h ambulatory monitoring following myocardial infarction.

To determine the prognostic value of supraventricular arrhythmias, in addition to ventricular arrhythmias and clinical variables after myocardial infarction, 99 consecutive patients had 24-h ambulatory monitoring within 2 weeks of discharge. All patients completed at least 4-year follow-up (mean 56 +/- 6 months). During follow-up there were 29 cardiac events (13 cardiac deaths and 16 reinfarctions). The highest risk was associated with ventricular tachycardia (positive predictive accuracy 100%, negative predictive accuracy 75%, risk ratio 4.0) and supraventricular tachycardia i.e. paroxysmal tachycardia or AV nodal tachycardia (positive predictive accuracy 86%, negative predictive accuracy 80%, risk ratio 4.2). By multivariate analysis, supraventricular tachycardia proved to be an independent predictive variable, in addition to ventricular tachycardia, premature ventricular depolarisations greater than or equal to 10 h-1 and the presence of Killip class greater than or equal to II while in the coronary care unit for future cardiac events. These data suggest that supraventricular tachycardias detected on 24-h ambulatory monitoring shortly after discharge carry a poor prognosis and may indicate a different pathophysiology as compared to ventricular tachycardias.

Aged↗

PubMed1989

Short-term and long-term prognosis after myocardial infarction: prognostic value of coronary anatomy and left ventriculography.

To assess prospectively short-term (1 year) and long-term (4 years) prognostic variables from heart catheterization, 325 consecutive patients of 65 years or less who survived a myocardial infarction were studied. In all coronary angiography and left ventriculography was performed 4-6 weeks after infarction. First year mortality rate was significantly higher in patients with an ejection fraction less than 0.30 (20%) than in patients with an ejection fraction greater than or equal to 0.30 (2%, P less than 0.001). During 4-year follow-up cumulative mortality was 44% in patients with an ejection fraction less than 0.30 vs 11% in patients with an ejection fraction greater than or equal to 0.30 (P less than 0.001). In patients who survived the first year after infarction, however, a low ejection fraction less than 0.30 was not associated with higher mortality rate during the subsequent 3 years. Mortality in patients with one-, two- or three-vessel disease was equally distributed in the first year. After 4 years patients with three-vessel disease had a significant higher mortality (32%) than patients with two- or one-vessel disease (12 and 11%, respectively; P less than 0.05). Reinfarction rate was higher in patients with an ejection fraction less than 0.30 (14%) than in patients with an ejection fraction greater than or equal to 0.30 (3%, P less than 0.05) in the first year. During 4-year follow-up reinfarction rate was 38% in patients with an ejection fraction less than 0.30 vs. 13% in patients with an ejection fraction greater than or equal to 0.30 (P less than 0.05). Again, in patients who survived the first year without reinfarction, an ejection fraction less than 0.30 had no prognostic value for recurrent myocardial infarction during the subsequent three years. Three-vessel disease had no higher reinfarction rate in the first year of follow-up: during 4 years, patients with three-vessel disease had a reinfarction rate (32%) compared to patients with two- and one-vessel disease (14 and 11%, respectively; P less than 0.05). It is concluded that an ejection fraction less than 0.30 is a major risk factor for cardiac death and reinfarction only in the first year after myocardial infarction. Beyond the first year, a subgroup of patients with three-vessel disease is at risk for both cardiac death and reinfarction during the three subsequent years.

Adult↗

PubMed1989

Efficacy and safety of rate responsive pacing in patients with coronary artery disease and angina pectoris.

The present study included 17 patients with angina pectoris and coronary artery disease in whom a rate responsive ventricular pacemaker (Medtronic Activitrax) had been implanted. All patients had an exclusively paced rhythm. Single blinded, random, cross-over treadmill tests in the rate responsive pacing mode (VVIR) and in the fixed-rate demand mode (VVI) were performed, with an interval of 4-6 weeks. Mean exercise duration increased by 25% during VVIR pacing. Maximal heart rate increased significantly during VVIR compared to VVI pacing (VVI = 74 +/- 2 bpm, VVIR = 116 +/- 8 bpm, P less than 0.001) as did the rate-pressure product (VVI = 10.850 +/- 1,124, VVIR = 16.628 +/- 2,110, P less than 0.001). Despite improved performance, the number of anginal attacks per week and the nitroglycerin consumption did not show a significant difference between the two pacing modes. It is concluded that rate responsive pacing is beneficial and safe in patients with angina pectoris and coronary artery disease.

Aged↗

PubMed1985

The elimination rate of 123I-heptadecanoic acid after intracoronary and intravenous administration.

When calculating the elimination rate of radioactivity after the administration of radioiodinated heptadecanoic acid (123I-HDA), background correction is necessary due to the high level of background activity. In the present study, the subtraction method of Freundlieb et al. was investigated on validity. This was done by comparing the half-time values of the elimination rate after intravenous (i.v.) and intracoronary (i.c.) injection. In the latter case, no background correction was necessary. Six patients undergoing cardiac catheterization were studied. Scintigraphy was performed after the injection of 123I-HDA into the left coronary artery and after i.v. injection. Half-time values were calculated from regions of interest drawn over myocardium perfused by the left-anterior descending branch (LAD) and the left circumflex artery (LCX). In the LAD region, the mean half-time value in the i.c. study was 22 min, while in the corrected i.v. study, the mean value was 27 min. In the LCX region, the half-time values were 24 and 33 min, respectively. The background-subtraction procedure proposed by Freundlieb et al. for i.v.-injected 123I-HDA is incomplete, as it resulted in half-time values that were higher than those of the i.c. study.

Arteries↗

PubMed1985

A computer program for the analysis of serial electrocardiograms from patients who suffered a myocardial infarction.

A program is described, which compares serial ECG recordings of patients, who suffered a myocardial infarction. The comparison of the ECGs is based on the measurements, delivered by the Modular ECG/VCG Interpretation System. The two most recent ECGs are compared and a trend analysis based on all ECG recordings of the patient is performed. The criteria in the comparison program are based, among others, on data obtained from a combined cardiological and respiratory survey in The Netherlands in 1973 and 1976.

Computers↗