Background Data about biochemical abnormalities (catecholamines) during vasovagal syncope (VVS) are available, but adrenergic myocardial structural damage may be hypothesized as well. Aim To study the global and regional adrenergic myocardial innervations in patients with VVS that was shown by head-up tilt table testing. Patients and methods Fifteen adult patients with WS were studied. The age of patients was 44 ± 18 years (17-73), nine were female and six were male. According to the tilt test results, five patients had cardioinhibition, six patients had vasodepressor syncope and four patients suffered from mixed-type WS. Ischemic heart diseases were excluded by normal 99mTc-MIBI rest-stress dipyridamol single-photon emission computed tomography (SPECT) results. A control group was formed from six healthy adult volunteers. To investigate cardiac sympathetic innervations 250-370 MBq iodine-123 meta-iodobenzylguanidine ( 123I-MIBG) was used. Fifteen minutes after the intravenous administration of 123I-MIBG early, and 2-3 h later, delayed planar myocardial and tomographic (SPECT) scintigraphies were performed. The heart-to-mediastinum count ratio (H/M) was calculated for both early and delayed images, together with the decay-corrected change rates. The regional 123I-MIBG uptake was visualized on SPECT slices and polar map images. The regional uptake was considered pathological below 50% compared with normal uptake sites. Results Delayed H/M ratios significantly depended on group (analysis of variance: P= 0.005), whereas early H/M values did not Although the decay-corrected myocardial MIBG uptake increased in time in controls, less wash-in or even wash-out could be observed in the VVS groups; however, difference from the controls was significant only in the vasodepressor group (Dunnett's t-test: P<0.05). All patients had regional 123I-MIBG uptake deficit in different regions. Conclusion In our patients with WS, global 123I-MIBG deficit was present frequently, and all patients had regional adrenergic nerve function deficit. These alterations may play a role in causing clinical symptoms and have importance in staging and treatment planning.
- Metaiodobenzylguanidine test
- Sympathetic innervations
- Vasovagal syncope
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging