Related Experiment Videos
Cardiac sympathetic nervous disintegrity is related to exercise intolerance in patients with chronic heart failure
H Atsumi1, Y Takeishi, S Fujiwara
1First Department of Internal Medicine, Yamagata University School of Medicine, Japan.
Insights
Enhanced cardiac sympathetic nervous activity, measured by iodine-123 meta-iodobenzylguanidine (123I-MIBG) imaging, is linked to reduced exercise capacity in heart failure patients. This non-invasive imaging can predict exercise tolerance.
Area of Science:
- Cardiology
- Nuclear Medicine
- Exercise Physiology
Background:
- Congestive heart failure (CHF) is associated with autonomic dysfunction, particularly increased cardiac sympathetic nervous activity.
- Assessing this activity non-invasively is crucial for understanding CHF pathophysiology and prognosis.
Purpose of the Study:
- To investigate the relationship between cardiac sympathetic nervous activity, evaluated using 123I-MIBG imaging, and exercise capacity in patients with CHF.
- To determine if 123I-MIBG imaging can predict exercise capacity in heart failure.
Main Methods:
- 24 patients with CHF (NYHA class II-III) and 7 controls underwent 123I-MIBG imaging to assess cardiac sympathetic activity via heart-to-mediastinum (H/M) ratio and washout rate.
- Patients also performed treadmill exercise tests to measure peak VO2 and VO2 at the anaerobic threshold (ATVO2).
Main Results:
- A significant positive correlation was observed between the delayed H/M ratio and exercise duration, peak VO2, and ATVO2.
- The 123I-MIBG washout rate showed a significant inverse correlation with exercise duration, peak VO2, and ATVO2.
Conclusions:
- Increased cardiac sympathetic nervous activity, as indicated by lower H/M ratios and higher washout rates on 123I-MIBG scans, is associated with exercise intolerance in CHF patients.
- 123I-MIBG imaging provides a valuable non-invasive tool for assessing cardiac sympathetic nervous activity and predicting exercise capacity in heart failure.
Abstract:
The aim of this study was to clarify the relationship between cardiac sympathetic nervous activity assessed by 123I-MIBG imaging and exercise capacity in patients with congestive heart failure. The subjects were 24 patients with heart failure (NYHA class II to III) and 7 normal controls. A dose of 148 MBq of 123I-MIBG was administered intravenously, and 5-min anterior planar images were obtained 20 min (early) and 4 h (delayed) after the injection of 123I-MIBG. Regions of interest were placed over the left ventricle and mediastinum, and the heart-to-mediastinum ratio (H/M ratio) was calculated as a fraction of the mean counts per pixel in the heart divided by those in the mediastinum. The washout rate from the myocardium was determined by: (early counts delayed counts) x 100/early counts (%). Treadmill exercise tests were performed using a ramp method within 1 week of the 123I-MIBG studies. During exercise, expired gas was analysed, and peak VO2 and VO2 at the anaerobic threshold (ATVO2) were measured. A significant linear correlation was found between the H/M ratio on delayed 123I-MIBG images and exercise duration (r = 0.48, P < 0.05), peak VO2 (r = 0.49, P < 0.05) and ATVO2 (r = 0.56, P < 0.01). The washout rate of 123I-MIBG was inversely correlated with exercise duration (r = -0.45, P < 0.05), peak VO2 (r = -0.51, P < 0.01), and ATVO2 (r = -0.50, P < 0.05). In conclusion, enhanced cardiac sympathetic nervous activity relates to exercise intolerance in patients with congestive heart failure. The non-invasive assessment of cardiac sympathetic nervous activity by 123I-MIBG can predict exercise capacity in human heart failure.