D Stone

Left ventricular aneurysm and congestive heart failure: value of exercise stress and isosorbide dinitrate in predicting hemodynamic results of aneurysmectomy.

In 12 patients with left ventricular aneurysm and chronic congestive heart failure, left ventricular functional reserve was assessed from the hemodynamic response to exercise stress after administration of isosorbide dinitrate. Two to 23 months (mean 8.6 months) after left ventricular aneurysmectomy hemodynamic measurements were made with the patient at rest and during exercise and were analyzed with respect to preoperative data. Left ventricular aneurysmectomy reduced mean left ventricular filling pressure from 25 to 17 mm Hg at rest (p < 0.02) and from 39 to 32 mm Hg during exercise (p < 0.05). There was no significant change in mean stroke volume index at rest or during exercise. Changes in resting and exercise hemodynamic indexes of left ventricular function produced by aneurysmectomy were inversely related to preoperative left ventricular function. Hence, hemodynamic status was less likely to improve In patients with good preoperative left ventricular function. Similarly, resting and exercise values for left ventricular function tended to improve in patients with reduced ejection fraction of the contractile section of the left ventricle. Left ventricular aneurysmectomy was generally effective in reducing left ventricular filling pressure but failed to achieve clinically important improvement in left ventricular performance during exercise. In patients with chronic congestive heart failure, left Ventricular aneurysmectomy should be performed only after careful assessment of preoperative left ventricular functional reserve.

Combined exercise radionuclide and hemodynamic evaluation of left ventricular aneurysmectomy

Twelve patients were studied by rest and exercise radionuclide ventriculography following left ventricular aneurysmectomy (LVA). Left ventricular filling pressure (LVFP) was also measured. Nine patients had been studied pre-LVA at rest and exercise before and after isosorbide dinitrate (ISDN). Resting ejection fraction (LVEF) improved after LVA (p less than 0.25), but exercise LVEF did not. End-diastolic volume (EDV) and resting LVFP also fell after LVA (p less than 0.25 for EDV, p less than 0.05 for LVFP) and although exercise LVFP fell (p less than 0.02), the values were abnormal in all patients. Ejection fraction of contractile segment (EFCS) from the resting radionuclide study pre-LVA was related to resting LVEF post-LVA (r = 0.71 p less than 0.02), although postoperative LVEF could not be predicted from preoperative EFCS in individual patients. Deterioration in LVEF and LVFP from rest to exercise post-LVA occurred both in patients with single-vessel occlusion and in those with multivessel coronary disease, irrespective of whether or not revascularization had been performed. Thus LVA is effective in improving resting ventricular function; exercise performance may remain abnormal even in patients without residual coronary disease.

Coronary haemodynamic effects of nifedipine. Comparison with glyceryl trinitrate.

The coronary haemodynamic effects of nifedipine and glyceryl trinitrate were compared in 22 patients undergoing investigations for suspected coronary artery disease. Myocardial blood flow was estimated by the coronary sinus thermodilution technique. In sinus rhythm nifedipine increased mean coronary sinus flow from 135 ml/min to 152 ml/min, and reduced arterio-coronary sinus oxygen difference from 12.4 to 10.96 ml/100 ml without causing a significant change in coronary vascular resistance or in myocardial oxygen consumption. Glyceryl trinitrate reduced mean coronary sinus flow from 165 to 111 ml/min, myocardial oxygen consumption from 19.2 to 11.9 ml/min, and arterio-coronary sinus oxygen difference from 11.7 to 10.9 ml/100 ml. There was a rise in coronary vascular resistance from 54 355 to 74 364 dynes s cm-5. During atrial pacing nifedipine reduced the arterio-coronary sinus oxygen difference from 11.99 to 11.0 ml/100 ml but had no significant effect on the other variables measured. Glyceryl trinitrate caused a fall in mean coronary sinus flow from 207 ml/min to 168 ml/min; myocardial oxygen consumption fell from 24 ml/min to 18 ml/min, while coronary vascular resistance rose from 41 714 to 51 234 dynes s cm-5. Direct comparison of the two drugs showed a significant difference in effects on coronary sinus flow and coronary vascular resistance in sinus rhythm. Both drugs appeared effective in relieving ischaemia as judged by a reduction of the incidence of pacing induced angina and an improvement in lactate status.

Dual isotope stress testing in congenital atresia of left coronary ostium. Applications before and after surgical treatment.

A 38-year-old women presented with an 11-year history of angina pectoris. Coronary arteriography disclosed a large right coronary artery which filled the entire left coronary tree retrogradely. The left main coronary artery ended blindly and was not connected to the aortic root. There were no atherosclerotic lesions in any vessel. Exercise thallium-20l scintigrams showed a perfusion defect in the anterior region of the left ventricle and exercise first pass radionuclide ventriculography showed anterior hypokinesis of the left ventricle with an ejection fraction of 54 per cent, compared with 60 per cent at rest. An aortocoronary saphenous vein graft was constructed to the left coronary artery. Four months after operation the patient is free from symptoms. Repeat thallium scintigrams were normal. Exercise radionuclide ventriculography after operation disclosed no wall motion abnormality, and ejection fraction on exercise was 70 per cent. The mechanism of angina in this patient is unclear but may have been related to the abnormal timing of delivery of blood to the left ventricular myocardium. Dual radionuclide stress testing showed abnormalities after operation. This non-invasive approach may be useful in the assessment of the physiological significance of coronary anomalies and of the value of corrective surgery.

The clinical validation of gold-195m: A new short half-life radiopharmaceutical for rapid, sequential, first pass angiocardiography in patients

With technetium-99m radiopharmaceuticals, first pass radionuclide angiocardiography is of limited use for multiple intervention studies because of the large radiation burden imposed on the patients. A portable mercury-195m/gold-195m generator has been developed capable of producing 17 to 20 mCi aliquots of the short half-life (30.5 seconds) gold-195m in less than 0.5 ml of generator eluate. Safety of the eluate has been established both in the experimental animal and in human beings. Fifteen patients underwent two first pass radionuclide angiograms with gold-195m, followed by a standard technetium-99m study. There was a close correlation between the left ventricular ejection fraction measured from gold and technetium studies (correlation coefficient [r] = 0.99, standard error of the estimate [SEE] 3.1%). Interobserver and sequential reproducibility of gold studies were excellent (mean variability ± standard deviation [SD]2.0 ± 2.9 and 0.6 ± 2.7%, respectively). Statistical reliability of the gold studies, as assessed from the observed left ventricular end-diastolic counts, matched that of technetium studies, and similarly, the images obtained from the two radiopharmaceuticals were identical. Residual count rates 5 minutes after first pass acquisition with gold were 480 ± 140 counts/s in the whole field of view, and 50 ± 30 counts/s over the left ventricle, these values being less than 1% of the residual counts after technetium. Accurate, reproducible, high count-rate first pass studies are obtainable with gold-195m, with a markedly reduced radiation exposure to the patients. It is now possible to perform rapid sequential first pass cardiac imaging studies without the constraints of an unacceptable high radiation burden.

Use of first-pass radionuclide ventriculography in assessment of wall motion abnormalities induced by incremental atrial pacing in patients with coronary artery disease.

In order to show that stress-induced changes in ventricular function can be determined by radionuclide techniques, 13 patients with coronary artery disease were paced to angina. Changes in ejection fraction and regional wall motion were measured from contrast angiograms and first-pass nuclear angiograms performed using a multicrystal gamma camera. A count-volume method applied to the nuclear technique demonstrated a significant fall in ejection fraction on pacing. The area-length method was also applied to both techniques and a significant fall in ejection fraction was induced by pacing in both contrast and nuclear angiograms. There was a good correlation between ejection fraction

Exercise first-pass radionuclide ventriculography in detection of coronary artery disease.

Thirty-four patients with coronary artery disease were exercised on a bicycle ergometer until they developed angina. There was a highly significant fall in ejection fraction from a mean of 61 1 to 52-9 which was more pronounced in the group with three vessel coronary artery disease. A coronary index was computed which took into account the extent and distribution of coronary artery lesions. Those patients with an index <0 3 (that is more severe disease) had greater falls in ejection fraction than those with higher indices. All five patients in whom there was a fall in ejection fraction of 15 per cent or more had triple vessel disease. Wall motion abnormalities were assessed by a hemiaxial method. Of 34 exercise-induced zones of wall motion abnormalities, 32 were in regions supplied by significantly stenosed coronary arteries. A test was defined as positive if there was an abnormal exercise ejection fraction (<50y%), an exercise-induced wall motion abnormality, or a fall in ejection fraction at angina of at least 10 per cent. Of the 19 patients with triple vessel disease, 18 (95 %) had a positive result, as did 11 of 15 (73%) patients with one or two vessel disease. A group of eight patients with normal coronary arteries were also exercised and in none of these was there a positive result. Exercise first-pass radionuclide ventriculography demonstrates changes in global and regional ventricular function in patients with coronary artery disease which are not present in normal subjects. It may also help to identify patients at high risk.

Development and use of the 195mHg195mAu generator for first pass radionuclide angiography of the heart

This paper describes the preparation and characteristics of a 195mHg-195mAu generator for clinical use in first-pass radionuclide angiography of the heart. The generator has an efficiency of elution of 20-30% which is maintained over the whole of its useful life. Over 100 patients have taken part in clinical trials with the generator.

Comparison of single plane and biplane radionuclide ventriculograms performed in oblique projections in patients with acute myocardial infarction.

Thirty-five patients were studied by first pass radionuclide ventriculography in both right anterior oblique and left anterior oblique projections, after an acute myocardial infarction. Left ventricular ejection fraction was measured in both obliques from the background corrected time-activity curves and the values correlated closely. Mean left ventricular ejection fraction from the two obliques correlated well with that measured from the ventricular perimeters using a biplane area-length formula. End-diastolic volume from the single plane right anterior oblique correlated with that measured using the biplane formula. Combined right and left anterior oblique projections allowed identification of akinetic sites in all patients, whereas the right anterior oblique alone failed to delineate akinetic sites in 1/10 (10%) of patients with anterior infarction, 2/9 (22%) with inferior infarction, and 6/16 (37%) with multiple areas ofinfarction. The left anterior oblique alone identified akinesis in all patients with anterior infarction, but failed in 2/9 (22%) with inferior infarction and 5/16 (31 %) with multiple sites ofinfarction. The mean percentage akinesis from both obliques showed a significant negative correlation with mean ejection fraction as did that from the right anterior oblique alone. Percentage akinesis from the left anterior oblique alone correlated less well with left ventricular ejection fraction. The combination of right and left anterior oblique radionuclide ventriculograms provides greater accuracy in the detection of akinetic segments, especially when multiple areas of infarction are present. The use of a single plane left anterior oblique alone may prove misleading in the quantification of wall motion abnormalities, and in this respect should be interpreted with caution.

Assessment of function of contractile segments in patients with left ventricular aneurysms by quantitative first pass radionuclide ventriculography. Haemodynamic correlation at rest and exercise.

Thirteen patients with left ventricular aneurysms complicating myocardial infarction were studied by contrast angiography and by first pass radionuclide ventriculography. The ejection fraction of the contractile segment (EFCS) was measured from both studies using a double hemishperoid model, and the values correlated closely. There was a monotonic relation between EFCS and stroke volume index measured from thermodilution cardiac outputs carried out simultaneously with the radionuclide study. When radionuclide ventriculography was performed at submaximal supine exercise, changes in EFCS paralleled changes in the total left ventricular ejection fraction in 10 of the 13 cases. In nine patients, changes in EFCS paralleled changes in stroke volume index and the relation between EFCS and stroke volume index was maintained at exercise. After administration of the vasodilator isosorbide dinitrate to 12 patients, repeat exercise radionuclide ventriculography showed an improvement in left ventricular ejection fraction and in eight patients EFCS improved. First pass radionuclide ventriculography can accurately estimate EFCS, which may be an important factor in predicting the likely response to aneurysmectomy. Changes in EFCS on exercise are reflected in changes in total left ventricular ejection fraction and stroke volume index. Isosorbide dinitrate may improve contractile segment function on exercise.