Abnormal cardiac innervation in patients with idiopathic ventricular fibrillation.
Idiopathic ventricular fibrillation (VF) is diagnosed in up to nearly 10% of survivors of out-of-hospital cardiac arrest. The arrhythmogenic substrate is unknown. This study examined the role of cardiac innervation as a possible contributor to this arrhythmia. Eight patients with idiopathic VF were compared with eight normal subjects (controls) by [123] I metaiodobenzylguanidine SPECT (MIBG), measuring peak uptake, late uptake, and clearance of the nuclear tracer. The left ventricle was divided in 13 segments in the bull's-eye target plot. Peak and late MIBG uptake was increased in the anterolateral segments (2,3,7,8) compared to the inferoposterior and septal segments, in controls and in patients. No difference was observed between controls and patients in the inferoposterior and septal segments. In contrast, a significantly higher MIBG uptake was observed in patients compared to controls in the anterolateral segments (94 +/- 4% vs 81 +/- 11%, P < 0.03 for peak uptake; 94 +/- 5% vs 79 +/- 12%, P < 0.01 for late uptake). No difference was observed in MIBG clearance in any segment in either study group. Cardiac sympathetic innervation is highly heterogeneous, though predominant in anterolateral segments in normal subjects. Patients with idiopathic VF exhibit the same distribution, though have a significantly greater density of sympathetic terminals in the anterolateral segments than controls, which may promote ventricular arrhythmias.
Biffi
Mauro
M
Istitute of Cardiology, University of Bologna, Via Massarenti 9, 40138 Bologna, Italy. mbiffi@orsola-malpighi.med.unibo.it
Fallani
Francesco
F
Boriani
Giuseppe
G
Fanti
Stefano
S
Kowoll
Ludovica
L
Pettinato
Cinzia
C
Monetti
Nino
N
Branzi
Angelo
A
D019797:3-Iodobenzylguanidine; D000328:Adult; D004562:Electrocardiography; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging / Q000294:innervation*; D006323:Heart Arrest / Q000150:complications; D006352:Heart Ventricles / Q000294:innervation; D006801:Humans; D008297:Male; D008875:Middle Aged; D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D013564:Sympathetic Nervous System / Q000473:pathology; D015899:Tomography, Emission-Computed, Single-Photon; D014693:Ventricular Fibrillation / Q000000981:diagnostic imaging / Q000209:etiology / Q000473:pathology*
D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine; C078700:technetium tc-99m tetrofosmin