Direct method for determining regional myocardial shortening after bypass surgery from radiopaque markers in man.

A new method is described for determining localized epicardial shortening in regions newly perfused after saphenous vein bypass grafting. Four to six radiopaque markers are sutured to the ventricular epicardium in pairs, 2 cm apart and 0 to 3 cm distal to the coronary anastomosis. Shortening fraction and time to onset of shortening are reported in 56 patients examined noninvasively with use of cinefluorography 1 week to 6 months after operation. The right coronary bypass region showed the greatest improvement in shortening fraction in 6 months (from 10.1 to 16.7 percent); the left anterior descending region showed the least (but still significant) improvement (from 8.6 to 11.5 percent). Paradoxical systolic expansion occurred predominantly in the region of the left anterior descending coronary bypass (95 percent of all such occurrences). Measurement error, observer variability and beat to beat variability were less important than the physiologic changes in the postoperative period. This technique is a direct method providing heretofore unavailable follow-up information on localized shortening in newly perfused myocardium after coronary bypass grafting.

Effect of flecainide on regional left ventricular wall motion after acute intravenous, acute oral and chronic oral administration late after coronary artery bypass grafting.

Epicardial marker motion was measured in 14 patients before flecainide administration, immediately after an intravenous dose of 2 mg/kg over 15 minutes (maximum 150 mg) and 15 minutes thereafter. Platinum epicardial markers had been implanted more than 4 years earlier at the time of coronary artery bypass grafting. Maximal and minimal marker separation (Lmax and Lmin) during the cardiac cycle were measured and regional shortening fraction (Lmax - Lmin)/Lmax) was determined as a percentage. After intravenous flecainide, a significant increase in end-diastolic (immediately after 2.8%; after 15 minutes 2.1%) and end-systolic (3.6% and 3.2%) regional dimensions was observed, together with a decrease in regional myocardial shortening (9.3% and 9.0%). One week later, after a single oral dose of 200 mg of flecainide, Lmax and Lmin had increased 2.4% and 2.7%, while regional myocardial shortening did not differ significantly from baseline values. In 10 patients measurements were repeated after 6 weeks of chronic oral treatment with 300 mg/day. Despite plasma flecainide levels similar to those after intravenous administration, no significant changes in end-diastolic and end-systolic dimensions or regional shortening fraction were observed. Thus, acute intravenous or oral flecainide administration increases regional end-diastolic and end-systolic dimensions, but only intravenous administration decreases regional shortening fraction. Values during chronic administration indicate that regional myocardial function is more affected at the time of rising or acutely changing flecainide plasma levels than when stable plasma levels are achieved.

Assessment of percutaneous transluminal coronary angioplasty by quantitative coronary angiography: diameter versus densitometric area measurements.

Cineangiograms of 138 patients who underwent percutaneous transluminal coronary angioplasty (PTCA) were analyzed with a computer-based coronary angiography analysis system. The results before and after dilatation are presented. In a first study group (120 patients), the severity of the obstructive lesions derived from the automatically detected contours was evaluated in absolute terms and in percent-diameter reduction. In a second group of patients, 18 coronary lesions were selected for their extreme severity and symmetric aspect before angioplasty as assessed from multiple views. In the second group, the densitometric percent-area stenosis was used to assess the changes in cross-sectional area after PTCA and was compared with the circular percent-area stenosis computed from the diameter measurements. Before PTCA, a good agreement exists between the densitometric percent-area stenosis and the circular percent-area stenosis. After PTCA, important discrepancies between these 2 types of measurements are observed. It is suggested that these discrepancies in results after PTCA can be accounted for by asymmetric morphologic changes in luminal cross section, which cannot be assessed accurately from diameter measurements in a single-plane view.

Comparison of preoperative, operative and postoperative variables in asymptomatic or minimally symptomatic patients to severely symptomatic patients three years after coronary artery bypass grafting: analysis of 423 patients.

During a follow-up period of 3 years, among a consecutive series of 423 patients who gave informed consent for recatheterization both 1 and 3 years after coronary artery bypass grafting, the incidence of severely symptomatic patients with New York Heart Association class III or IV was 19% (79 of 423). The predictive value of approximately 80 clinical, angiographic and perioperative variables was too low to be of clinical value. Adverse clinical outcome was associated with a high closure rate of the grafts. Forty-six percent of the patients could not undergo reoperation because of unsuitable coronary anatomy. With intensive medical therapy half of these patients improved to functional class I or II, while of those patients who were reoperable 32% improved to class I or II with intensive pharmacologic treatment instead of reoperation. The nonresponders underwent reoperation, which resulted in improvement of symptoms to functional class I or II in most (83%).

The role of the personal computer in the cardiac catheterization laboratory: an integrated approach to information management.

A personal computer-based data management system for the cardiac catheterization laboratory is described. This is a cooperative effort on the part of the Dutch academic hospitals, through the Interuniversity Cardiology Institute, to put in place a more uniform structure for data collection and reporting in the context of cooperative studies. The major design criteria included the necessity that the system provide a clear and present benefit to the users in terms of their day-to-day work. This requires a practical data entry package together with a full reporting capability, including management tools for supervision of the catheterization laboratory in general. Ancillary activities include quantitative analysis of ventriculograms and an elementary statistics package with graphics. To facilitate supportability of the system, commercially available packages for data base management, text processing, and communications have been used to advantage. After a prototype test phase involving two centers, five other centers have been equipped with similar systems and used successfully in the majority.

Myocardial radiopaque markers used to quantify minor axis shortening for follow-up studies in experimental surgery. I. Recording and analysis techniques. II. Comparison with contractility indices.

This work further validates the use of radiopaque epicardial marker motion for quantifying myocardial shortening in long duration follow-up studies. Mean velocity and extent of minor axis shortening were determined in 8 dogs filmed daily for 6--10 days postoperative. As an independent measure of contractility, peak dP/dt was also determined. A useful approximation to the mean ejection slope was developed which uses the end diastolic minor axis 50 msec after the Q wave, and end systolic minor axis 150 msec after the Q wave of the ECG.

Problems and pitfalls in a clinical research data management system.

The problems and pitfalls encountered in the computerized data bank for the Netherlands Coronary Surgery (NCS) study are reviewed. This study involved 848 patients seen before coronary artery surgery and at 1 and 3 yr after surgery. Nineteen data forms were used resulting in maximally 1142 variables per patient. The importance of quality control is emphasized as well as the efficient transfer of information from data bank to statistical processing.

Do coronary collaterals influence the outcome of bypass graft surgery?

The importance of coronary collateralization on the outcome of bypass grafting was evaluated in patients recatheterized one year after surgery. Because the severity of coronary artery disease correlated with the extent of collateralization, and ventricular function with previous myocardial infarction, we performed a matched pair study where differences in these variables were eliminated between pairs which differed only with respect to the extent of collateralization visualized during angiography. From a data bank of 814 operated patients, 143 matched pairs were formed. In the matched pair series of patients collaterals appear to provide some degree of additional blood flow to ischemic areas to allay resting symptoms before surgery, but collaterals are inadequate to meet the additional requirements of pacing-induced stress. The 2 groups were indistinguishable one year after bypass surgery. As the non-collateralized group was more symptomatic before surgery, it demonstrated greater subjective benefit from the procedure, however, this would be obscured in a consecutive series where collateralization generally correlates with severity of coronary artery disease.

Recovery from circulatory depression after coronary artery bypass surgery.

The direct traumatic effects of coronary artery bypass surgery may counter-balance the expected improvement of myocardial function in the early postoperative period. In 55 patients, the regional shortening fraction was measured over 12 months using radiopaque epicardial markers pairs implanted during surgery in the newly perfused regions. The time course of cardiothoracic ratio, heart rate and cuff blood pressure was documented. All patients were catheterized before surgery and 1 year afterwards. There is an initial depression in myocardial function lasting up to 3 months after surgery which is not directionally related to changes in loading conditions or chronotropic state, but most likely to recovery of the myocardium from perioperative injury. At 1 year after surgery the overall ventricular function is unchanged. The evaluation of ventricular function after coronary artery bypass grafting should be performed no sooner than 3 months after surgery to avoid this transient period of depressed myocardial performance.

Incidence and prognostic implications of repetitive ventricular complexes during pre-discharge bicycle ergometry after myocardial infarction.

The clinical significance of repetitive ventricular complexes (RVCs) during pre-discharge bicycle ergometry after acute myocardial infarction has been assessed in 408 consecutive patients. RVCs occurred in 32 patients (8%). When compared to patients without RVCs, those with RVCs had a larger infarction, a higher prevalence of heart failure and late sustained ventricular tachycardia or fibrillation, a lower radionuclide ejection fraction and more frequent RVCs during pre-discharge 24-hour electrocardiographic monitoring. During a follow-up 30 patients died, 17 suddenly. Mortality was 15% (N = 5) in patients with RVCs during exercise test and 7% (N = 25) in those without RVCs. Sudden death occurred in only one patient with RVCs. When multivariate analysis was applied to clinical and exercise test data, RVCs during exercise did not predict cardiac mortality independent of variables related to left ventricular function, such as a history of previous myocardial infarction, persistence of heart failure in the late hospital phase and the extent of blood pressure rise during exercise test.

Effect of long-term oral nifedipine therapy on left ventricular regional wall function at rest and during supine bicycle exercise.

15 patients, 1 to 3 year after coronary bypass surgery, underwent symptom limited supine bicycle exercise tests without nifedipine and after acute and chronic (3 months) administration of the drug. Haemodynamic variables were monitored as was epicardial marker motion, using biplane cineradiography during exercise, the markers having been implanted at the time of surgery. We found significant (P less than 0.001) reductions in end-diastolic and end-systolic regional dimensions at maximal exercise after oral nifedipine, associated with a significant reduction in exertional angina, which persisted during long-term treatment. No adverse effects of the drug were observed.

Prognostic value of predischarge 12 lead electrocardiogram after myocardial infarction compared with other routine clinical variables.

The prognostic value of QRS score (Selvester), ST depression, ST elevation, extrasystoles, P terminal force in V1, and QTc derived from the predischarge 12 lead electrocardiogram was assessed after myocardial infarction in 474 patients without intraventricular conduction defects, ventricular hypertrophy, or atrial fibrillation. The usefulness of these results in risk assessment was compared with that of other clinical data. During follow up 45 patients died. Logistic regression analysis showed that QRS score, ST depression, and QTc were independently predictive of cardiac mortality. When multivariate analysis was applied to clinical and electrocardiographic data together, however, the 12 lead electrocardiogram did not provide independent information additional to that provided by other routine clinical findings and laboratory tests such as a history of previous myocardial infarction, clinical signs of persistent heart failure, indication for digitalis or antiarrhythmic drugs at discharge, and enlarged heart on chest x ray. In conclusion, the electrocardiogram has important prognostic value; however, it is not powerful enough to further improve the risk assessment of post-infarction patients.

Incidence of restenosis after successful coronary angioplasty: a time-related phenomenon. A quantitative angiographic study in 342 consecutive patients at 1, 2, 3, and 4 months.

Data from experimental, clinical, and pathologic studies have suggested that the process of restenosis begins very early after coronary angioplasty. The present study was performed to determine prospectively the incidence of restenosis with use of the four National Heart, Lung, and Blood Institute and the 50% or greater diameter stenosis criteria, as well as a criterion based on a decrease of 0.72 mm or more in minimal luminal diameter. Patients were recatheterized at 30, 60, 90, or 120 days after successful percutaneous transluminal coronary angioplasty (PTCA). After PTCA all patients received 10 mg nifedipine three to six times a day and aspirin once a day until repeat angiography. Of 400 consecutive patients in whom PTCA was successful (less than 50% diameter stenosis), 342 underwent quantitative angiographic follow-up (86%) by use of an automated edge-detection technique. A wide variation in the incidence of restenosis was found dependent on the criterion applied. The incidence of restenosis proved to be progressive to at least the third month for all except NHLBI criterion II. At 4 months a further increase in the incidence of restenosis was observed when defined as a decrease of 0.72 mm or more in minimal luminal diameter, whereas the criteria based on percentage diameter stenosis showed a variable response. The lack of overlap between the different restenosis criteria applied affirms the arbitrary nature of angiographic definitions currently in use. Restenosis should be assessed by repeat angiography, and preferably ascertained according to the change in absolute quantitative measurements of the luminal diameter.

Angina pectoris, one to 10 years after aortocoronary bypass surgery.

The incidence of angina pectoris (AP) after bypass surgery was assessed in 1041 patients operated on consecutively between 1971 and 1980. Of the 977 survivors, 920 (94%) participated in the study with a followup time varying from 1 to 10 years (mean 3.5 years). Post-operative angina pectoris was present at 1 year in 277 patients (30%), at 3 years in 46%, at 8 years in 50%. The pain limited usual physical activities in 17.5%, 30% and 25%, respectively at these times. Nonetheless, 89% of the respondents felt improved by surgery. Factors without predictive value for late outcome were sex, number of pre-operative diseased vessels, and pre-operative ejection fraction. A correlation was found between post-operative AP and younger age at surgery in the males only (P less than 0.001); between AP and patency rate of the bypass graft (P less than 0.005) and with the status of the coronary arterial tree at three years post-operatively (P less than 0.001) in both sexes. The percentage of patients with recurrent AP increased with time after surgery up to 3 years, but remained stable thereafter. In conclusion, post-operative AP seems initially related to decreased functioning of the bypass graft, later to progression of coronary sclerosis in the native circulation.