Geert T. Meester

Coronary artery atherosclerosis: severity of the disease, severity of angina pectoris and compromised left ventricular function

To determine if the severity of angina pectoris and the degree of altered left ventricular function correlated with the severity and extent of the underlying coronary artery disease, a coronary scoring system was derived. The system was based on the severity of luminal diameter narrowing and weighted according to the usual flow to the left ventricle in each coronary vessel. Thus, the most weight was given to the left main coronary artery, followed by the left anterior descending, circumflex, and right coronary arteries. The resultant number was an indicator of the overall severity of the obstructive coronary artery disease. A coronary arterial system with no obstructive disease was scored as zero and the greater the degree of obstructive disease present, the higher the coronary score. From 202 subjects, four groups were evaluated: group 1—coronary score = 0.5–4.5 (n = 10); group 2—coronary score = 10.5–12.5 (n = 11); group 3—coronary score = 17.5–20.5 (n = 11); and group 4—coronary score = 25.0–36.0 (n = 11). All subjects had coronary artery bypass surgery and had preoperative and l-year postoperative cardiac catheterization, including atrial pacing to maximal heart rate. The groups could not be separated on the basis of angina frequency, resting heart rate, cardiac index, left ventricular end-diastolic pressure, peak paced left ventricular end-diastolic pressure, dP/dt, V max, left ventricular end-diastolic volume index, left ventricular end-systolic volume index, stroke volume index, ejection fraction or mean circumferential fiber shortening velocity. Thus, based on this study, the severity of coronary artery disease does not statistically correlate with the frequency of angina pectoris or produce a predictable degree of altered left ventricular function. The frequency of angina pectoris cannot be used to predict prognosis orthe adequacy of myocardial revascularization.

Quantitative assessment of regional left ventricular motion using endocardial landmarks

In this study the hypothesis is tested that the motion pattern of small anatomic landmarks, recognizable at the left ventricular endocardial border in the contrast angiocardiogram, reflects the motion of the endocardial wall. To verify this, minute metal markers were inserted in the endocardium of eight pigs with a novel retrograde transvascular approach. Marker motion was subsequently recorded with roentgen cinematography and compared with the motion of the landmarks on the endocardial contours detected from the contrast ventriculogram with an automated contour detection system. Linear regression analysis of the directions of the systolic metal marker and endocardial landmark pathways yielded a correlation coefficient of 0.86 and a standard error of the estimate of 10.3 degrees. Landmark pathways were also measured in 23 normal human left ventriculograms. Normal left ventricular endocardial wall motion during systole, as observed in the 30 degrees right anterior oblique view, is characterized by a dominant inward transverse motion of the opposite anterior and inferoposterior walls and a descent of the base toward the apex. The apex itself is almost stationary. On the basis of these observations, a widely applicable model for the assessment of left ventricular wall motion is described in mathematical terms.

Interaction of left ventricular relaxation and filling during early diastole in human subjects

Seventeen patients with coronary artery disease were studied with cineangiography and simultaneous tip manometry at resting heart rate and maximal tachycardia induced by atrial pacing. During early diastole, defined as the interval from the opening of the mitral valve to the point of minimal left ventricular pressure, 20 percent of total ventricular filling took place at resting heart rate, but 62 percent occurred during tachycardia. Minimal pressure was significantly correlated with the time constant of pressure decay during the isovolumic phase (r = 0.75 at resting heart rate and r = 0.81 during tachycardia). The measured minimal pressure could be predictd by extrapolating the exponential decay of ventricular isovolumic pressure to the time of occurence of the minimal pressure, which occurred on average 2.7 time constants from the peak negative rate of change of pressure. At resting heart rate the time constant of relaxation was inversely correlated with ventricular inflow volume (r = -0.64) and inflow rate (r = -0.72). It is concluded that left ventricular relaxatin has a relevant role in early diastolic pressure-volume relations and increases during tachycardia.

Vaporization of atherosclerotic plaques by spark erosion

An alternative to the laser irradiation of atherosclerotic lesions has been developed. A pulsed electrocardiogram R wave-triggered electrical spark erosion technique is described. Controlled vaporization of fibrous and lipid plaques with minimal thermal side effects was achieved and documented histologically in vitro from 30 atherosclerotic segments of six human aortic autopsy specimens. Craters with a constant area and a depth that varied according to the duration of application were produced. The method was confirmed to be electrically safe during preliminary in vivo trials in the coronary arteries of seven anesthetized pigs. The main advantages of this technique are that it is simpler to execute than laser irradiation and potentially more controllable.

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.

Contouromat--a hard-wired left ventricular angio processing system. I. Design and application.

Abstract The Contouromat is a hard-wired system designed for operator interactive automated outlining of left ventricular contrastangiograms. The cineangiogram of the left ventricle is converted into videoformat and the system allows real-time detection of the outlines. The detected contour is mixed into the original image for visual feedback. The operator may intervene in the detection procedure by means of a writing tablet. In the first frame to be analyzed the operator indicates the aortic valve plane with two starting points. With this system analyzing time for quantitative angiocardiography has been reduced by 75%. The consistency of the contouring process is also improved. Furthermore, new applications, such as the detection and follow up of irregularities at the endocardial surface during left ventricular motion, can be introduced.

Long term follow-up after coronary artery bypass graft surgery. Progression and regression of disease in native coronary circulation and bypass grafts.

coronary artery bypass graft surgery. The extent of coronary artery disease was scored according to the recommendations of the American Heart Association and quantified following the method of Leaman. Patency in 570 grafts at one year was 79-6% and at three years 76-5%. The majority of grafts (83-5%) showed no change from one year to three years, 1144% showed progression in disease, and 5-1% showed regression. The majority of grafts which occlude do so in the first year after

Contouromat—A hard-wired left ventricular angio processing system. II. Performance evaluation

Abstract An operator-interactive dedicated hard-wired system which allows the automatic detection of the left ventricular outline in real time is evaluated using 29 left ventricular angiograms in RAO projection, randomly selected as a representative set taken from our clinical files. In 17 angiograms the film quality was such that the left ventricular contours could be processed automatically over two cardiac cycles, whereas only one cardiac cycle was processed in the other 12 angiograms due to low contrast in the second cycle. The average number of corrections per processed frame was 0.5 ± 0.3 (man ± SD) for the double-cycle films and 0.8 ± 0.4 for the single-cycle films. The percentages of corrected frames requiring small unimportant corrections with a resulting calculated volume change of less than 5% for the double- and single-cycle films are 45.2% and 55.4%, respectively. The average processing time T per cine frame for the double- and single-cycle films is T = 2.9 + 6 N sec and T = 4.5 + 6.7 N sec, respectively, where N is the number of applied corrections per frame. The processing time is mainly determined by the operators decision and interaction speed. For such an automated left ventricular contour detector to have clinical significance the operator must make the final decision as to the acceptability of the detected outline.

Automatic data processing in the cardiac catheterization laboratory.

A review of automatic data processing in the cardiac catherization lab is presented. The emphasis placed on on-line manometry, indicator dilution and off-line quantitative ventriculography. The system organization is described and several specific examples given to illustrate the level of detail necessary to specify such a system. The clinical use of the system is described together with an evaluation of the original design goals in terms of the actual performance of the system. A few unexpected benefits have emerged with respect to quality control and reliability, but one of the original design goals, speeding up the catheterization procedure, has proven to be unrealistic. The next logical steps in the software and hardware evolution are described with the emphasis placed on making the system a more effective tool for the clinician.

Hemodynamic Effect of Nifedipine (Adalat) in Patients Catheterized for Coronary Artery Disease

Previous investigations on the effect of Adalat on cardio-hemodynamics have shown the following results: There seems to be agreement on the fact that Adalat causes a definite fall in both systolic and diastolic systemic blood pressure. It also increases coronary blood flow, caused by a decrease in coronary resistance. Heart rate was shown to be higher or to remain stable in different studies, after the administration of the drug, as was the cardiac index. As far as contractility parameters are concerned, according to Vater et al. [2] there is primarily an inhibitory action on myocardial contractility. Lichtlen [1] found an increase in peak dp/dt, together with an increase in heart rate and decrease in left ventricular end-dia-stolic pressure. It is not clear, whether these last effects are interrelated, i.e., is the higher peak dp/dt the result of a positive inotropic action of Adalat, independent of a concomitantly higher heart rate, or is it the result of the positive inotropic effect of the higher heart rate itself?