Effects of cardiac sympathetic innervation on regional wall motion abnormality in patients with long QT syndrome.
OBJECTIVE
To assess the spatial relation between regional cardiac sympathetic innervation and regional ventricular repolarisation indicated by ventricular wall motion abnormality in patients with congenital long QT syndrome.


METHODS
Regional percentage uptake and washout rate of (123)I metaiodobenzylguanidine (MIBG) were measured to assess cardiac sympathetic innervation in septum, anterior wall, lateral wall, and posterior wall. Left ventricular short axis images on echocardiography were digitised to reconstruct digitised M mode echocardiograms, from which left ventricular wall thickness curves were obtained. The wall thickening time (ThT) was defined as the period in which the instantaneous wall thickness exceeded 90% of the maximum wall thickness. The ThT was measured from the ventricular wall thickness curve at the same segments where regional percentage uptake and washout rate of (123)I MIBG were measured.


METHODS
Seven patients with long QT syndrome.


RESULTS
The regional washout rate (mean (SD)) of (123)I MIBG in patients with long QT syndrome was greater in the segments with decreased percentage uptake of (123)I MIBG than in those without (17.4 (10.6)% v 9.7 (16.5)%, p < 0. 03). ThT in segments both with and without decreased percentage uptake of (123)I MIBG was longer than in control subjects (p < 0. 0001). ThT was longer in the segments with decreased percentage uptake of (123)I MIBG than in those without (199 (70) ms v 150 (66) ms, p = 0.0018).


CONCLUSIONS
Activation of regional cardiac sympathetic terminals is likely to participate in additional regional prolongation of ventricular repolarisation in patients with long QT syndrome.
Yamanari
H
H
Department of Cardiovascular Medicine, Okayama University Medical School, 2-5-1 Shikata-cho, Okayama 700-8558, Japan.
Nakayama
K
K
Morita
H
H
Miyazi
K
K
Fukushima
K
K
Matsubara
H
H
Emori
T
T
Ohe
T
T
D019797:3-Iodobenzylguanidine; D000293:Adolescent; D000328:Adult; D000368:Aged; D004452:Echocardiography; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging / Q000294:innervation*; D006801:Humans; D008133:Long QT Syndrome / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D013564:Sympathetic Nervous System / Q000000981:diagnostic imaging
D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine