Relation between coronary anatomy and serial changes in left ventricular function on exercise: a study using first pass radionuclide angiography with gold-195m

Left ventricular function during interval and steady state exercise

PURPOSE

Interval training (INT) is a commonly used method of exercise training in both athletic and clinical populations. Although we generally understand left ventricular (LV) function during steady state (SS) exercise, there are no data regarding LV function during INT.

METHODS

We studied eight healthy, physically active volunteers during upright cycle ergometry during 15 min of both SS and INT, at the same average power output (90% individual anaerobic threshold), using first pass radionuclide ventriculography. During INT (60s/60s), measures of LV function were made during work (220 W) after 4 and 12 min and during recovery (120 W) after 7 and 15 min. These were compared with the average of four temporally matched measures made during SS (170 W).

RESULTS

During INT, LV ejection fraction increased from rest (67 +/- 6%) to 77 +/- 5, 80 +/- 5, 77 +/- 5 and 79 +/- 4% after 4, 7, 12, and 15 min, respectively. During SS, LV ejection fraction was not significantly different at rest (70 +/- 4%) or during exercise (76 +/- 4, 79 +/- 4, 80 +/- 3, and 81 +/- 3%) after 4, 7, 12, and 15 min, respectively. Other measures of LV function (HR, BP, LV volumes, cardiac output, systemic vascular resistance, peak emptying, and filling rates) were likewise similar during temporally matched measurements during INT and SS.

CONCLUSIONS

Although there were the expected transitions of ejection fraction with work and recovery, the overall hemodynamic picture during INT was very similar to SS. These data suggest that LV function during INT is not substantially different to that during SS.

Physiological and pathological aspects of exercise left ventricular function

Measures of left ventricular function during exercise provide information that is more accurate than the exercise ECG in the diagnosis of coronary artery disease, supportive of the data provided by myocardial perfusion studies, and of great prognostic significance. We review basic methods for evaluating left ventricular function during exercise and responses to various types of exercise, including incremental exercise and exercise training conditions. Additionally, we review changes in both incremental exercise test responses and responses to training in various pathological conditions. Case reports are included to illustrate the utility of measuring left ventricular function during exercise.

Stress imaging. Current clinical options for the diagnosis, localization, and evaluation of coronary artery disease

As technology advances, new methods evolve. In this article, the methods of stress testing and related imaging in coronary disease are addressed, and dynamic and pharmacologic stress, direct and indirect methods, are defined and evaluated. The stress imaging methods related to the modalities of scintigraphy and ultrasound are reviewed and their advantages and disadvantages assessed in view of scientific and economic factors.

Rate of change of left ventricular ejection fraction during exercise is superior to the peak ejection fraction for predicting functionally significant coronary artery disease

OBJECTIVE

To detect and characterise rapid temporal changes in the left ventricular response to exercise in patients with ischaemic heart disease and to relate these changes to the functional severity of coronary artery disease.

BACKGROUND

The gamma camera does not allow the detection of rapid changes in cardiac function during exercise radionuclide ventriculography, the monitoring of which may improve the assessment of patients with ischaemic heart disease.

METHODS

A miniature nuclear probe (Cardioscint) was used to monitor continuously left ventricular function during exercise in 31 patients who had coronary angiography for suspected coronary artery disease. A coronary angiographic jeopardy score was calculated for each patient.

RESULTS

The coronary jeopardy score ranged from 0 to 12 (median 4). Ejection fraction fell significantly during exercise from 46% to 34%. Patients were divided into two groups based on the response of their ejection fraction to exercise. In 14 patients (group I), the peak change in ejection fraction coincided with the end of exercise, whereas in the other 17 patients (group II) the peak change in ejection fraction occurred before the end of exercise, resulting in a brief plateau. The peak change in ejection fraction and the time to its occurrence were independent predictors of coronary jeopardy (r = -0.59, p < 0.001 for peak change and r = -0.69, p < 0.001 for time to that change). The rate of change in ejection fraction was the strongest predictor of coronary jeopardy (r = -0.81, p < 0.001). In group I the peak change in ejection fraction was a poor predictor severity of coronary disease (r = -0.28, NS), whereas the time to peak and the rate of change in ejection fraction were good predictors (r = -0.65 and r = -0.73, p < 0.01). In group II the peak, the time to the peak, and the rate of change in ejection fraction were good predictors of coronary jeopardy (r = -0.75, r = -0.61, and r = -0.83, p < 0.01).

CONCLUSION

The rate of change of ejection fraction during exercise can be assessed by continuous monitoring of left ventricular function with the nuclear probe, and is the best predictor of functionally significant coronary artery disease.

Limitations in the interpretation of rest-exercise ejection fraction changes after early thrombolytic therapy during acute myocardial infarction

The effect of exercise on left ventricular wall motion in the infarct and noninfarct regions, and their contribution to the global ejection fraction response to exercise was evaluated in 24 patients studied at least 2 weeks following thrombolytic therapy for acute myocardial infarction. To achieve this goal, a nonstandard protocol was used: contrast ventriculography was performed at rest and immediately following 3 minutes of supine bicycle exercise at 50 watts. Wall motion in the infarct and noninfarct regions was measured using the centerline method. The global ejection fraction response to exercise correlated poorly with the exercise response of motion in the infarct region (r = 0.38). In 15 of the 24 patients, the function of the infarct and noninfarct regions changed in opposing directions, and in only 8 (53%) of these did the global ejection fraction response follow the exercise response of motion in the infarct region. The motion of the noninfarct region was the predominant influence on the ejection fraction response in the other 7 patients. Subgroup analysis revealed that the global ejection fraction response was more dependent on the response of motion in the anterior wall (r = 0.71, p less than 0.001) than in the inferior wall (r = 0.16), regardless of infarct location. The regional wall motion response to exercise also better distinguished reperfused from nonreperfused patients than did the ejection fraction response. These results indicate that the global ejection fraction response to exercise may be an unreliable indicator of the functional status of the infarct region.(ABSTRACT TRUNCATED AT 250 WORDS)

Nonischemic changes in right ventricular function on exercise. Do normal volunteers differ from patients with normal coronary arteries?

Factors other than ischemia may alter right ventricular function both at rest and on exercise. Normal volunteers differ from cardiac patients with normal coronary arteries with regard to their left ventricular response to exercise. This study examined changes in right ventricular function on exercise in 21 normal volunteers and 13 patients with normal coronary arteries, using first-pass radionuclide angiography. There were large ranges of right ventricular ejection fraction in the two groups, both at rest and on exercise. Resting right ventricular ejection fraction was 40.2 +/- 10.6% (mean +/- SD) in the volunteers and 38.6 +/- 9.7% in the patients, p = not significant, and on exercise rose significantly in both groups to 46.1 +/- 9.9% and 45.8 +/- 9.7%, respectively. The difference between the groups was not significant. In both groups some subjects with high resting values showed large decreases in ejection fraction on exercise, and there were significant negative correlations between resting ejection fraction and the change on exercise, r = -0.59 (p less than 0.01) in volunteers, and r = -0.66 (p less than 0.05) in patients. Older volunteers tended to have lower rest and exercise ejection fractions, but there was no difference between normotensive and hypertensive patients in their rest or exercise values. In conclusion, changes in right ventricular function on exercise are similar in normal volunteers and in patients with normal coronary arteries. Some subjects show decreases in right ventricular ejection fraction on exercise which do not appear to be related to ischemia.

Sex differences in exercise induced left ventricular dysfunction in patients with syndrome X

Clinical, electrocardiographic, and scintigraphic data were reviewed from 32 patients (18 men and 14 women) who had syndrome X (chest pain, evidence of ischaemia, and normal coronary arteries without coronary vasospasm). The mean (SD) resting left ventricular ejection fraction, determined by first pass radionuclide angiography was 62.6 (9.2)% and was greater than 50% in all subjects. There was no significant difference between men and women. On exercise, left ventricular ejection fraction decreased significantly to 57.4 (13.0)%. In 17 of 32 subjects there was a fall in left ventricular ejection fraction of greater than 5%, and regional wall motion abnormalities developed in 12 subjects. The fall in left ventricular ejection fraction on exercise was significant in women (from 61.9 (8.5)% at rest to 54.0 (9.8)% on exercise) but not in men (from 63.2 (9.8)% at rest to 60.0 (14.8)% on exercise). Exercise left ventricular ejection fraction fell by greater than 5% in 10 (71%) of 14 women and in seven (39%) of 18 men. Dyskinetic segments developed in eight (57%) of 14 women and only four (22%) of men. Exercise duration in women was significantly shorter than in men (4.1 (1.5) vs 6.6 (2.1) minutes) and was the only one of several clinical and scintigraphic variables that correlated with the change in left ventricular ejection fraction on exercise. In this selected group of subjects with chest pain and angiographically normal coronary arteries, exercise induced left ventricular dysfunction, as shown by a fall in ejection fraction or the development of regional abnormalities, is a common finding. These are more likely to occur in women than men and are associated with a lower exercise capacity. The data suggest that the sex of the patient is important in the interpretation of the non-invasive evaluation of subjects suspected of having syndrome X.

Effects of projection and background correction method upon calculation of right ventricular ejection fraction using first-pass radionuclide angiography

There is no consensus as to the best projection or correction method for first-pass radionuclide studies of the right ventricle. We assessed the effects of two commonly used projections, 30 degrees right anterior oblique and anterior-posterior, on the calculation of right ventricular ejection fraction. In addition two background correction methods, planar background correction to account for scatter, and right atrial correction to account for right atrio-ventricular overlap were assessed. Two first-pass radionuclide angiograms were performed in 19 subjects, one in each projection, using gold-195m (half-life 30.5 seconds), and each study was analysed using the two methods of correction. Right ventricular ejection fraction was highest using the right anterior oblique projection with right atrial correction 35.6 +/- 12.5% (mean +/- SD), and lowest when using the anterior posterior projection with planar background correction 26.2 +/- 11% (p less than 0.001). The study design allowed assessment of the effects of correction method and projection independently. Correction method appeared to have relatively little effect on right ventricular ejection fraction. Using right atrial correction correlation coefficient (r) between projections was 0.92, and for planar background correction r = 0.76, both p less than 0.001. However, right ventricular ejection fraction was far more dependent upon projection. When the anterior-posterior projection was used calculated right ventricular ejection fraction was much more dependent on correction method (r = 0.65, p = not significant), than using the right anterior oblique projection (r = 0.85, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)