Severely impaired cardiac autonomic nervous activity after the Fontan operation.
BACKGROUND
Elevated neurohumoral activity and an abnormal cardiopulmonary response to exercise are well-established characteristics in patients after the Fontan operation. However, there have been few studies addressing cardiac autonomic nervous activity (CANA) in these patients.


RESULTS
We evaluated CANA in 63 post-Fontan patients and 44 controls. Cardiac parasympathetic nervous activity (PSNA) was estimated by heart rate (HR) changes after cholinergic blockade, HR variability, and arterial baroreflex sensitivity. Cardiac sympathetic nervous activity was estimated by the heart to mediastinum [(123)I]metaiodobenzylguanidine activity ratio (H/M) and the HR increase (DeltaHR) after isoproterenol infusion (beta). DeltaHR and peak oxygen uptake (VO(2)) were measured by exercise test. There was no difference in beta between the Fontan group and controls. PSNA and H/M were markedly lower than in controls (P<0.001). PSNA and beta were related to DeltaHR (P<0.05); however, peak VO(2) was not correlated with DeltaHR. Neither PSNA nor H/M was associated with clinical features, including hemodynamics, type of repair, number of surgical procedures, age at Fontan operation, or follow-up period, and administration of an angiotensin-converting enzyme inhibitor did not improve the impaired CANA in these patients.


CONCLUSIONS
After the Fontan procedure, postsynaptic beta-sensitivity is maintained and is important in DeltaHR during exercise as is PSNA, although DeltaHR does not determine exercise capacity. The lack of a relationship between CANA and clinical features implies that, in addition to surgical damage, the Fontan circulation per se may impair CANA. Angiotensin-converting enzyme inhibitor administration does not change this abnormality.
Ohuchi
H
H
Department of Pediatrics, National Cardiovascular Center, Osaka, Japan. hohuchi@hsp.ncvc.go.jp
Hasegawa
S
S
Yasuda
K
K
Yamada
O
O
Ono
Y
Y
Echigo
S
S
D000293:Adolescent; D000367:Age Factors; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000627:therapeutic use; D009320:Atrial Natriuretic Factor / Q000378:metabolism; D001341:Autonomic Nervous System / Q000187:drug effects; D001342:Autonomic Nervous System Diseases / Q000209:etiology* / Q000517:prevention & control; D001794:Blood Pressure / Q000187:drug effects; D002648:Child; D015444:Exercise / Q000502:physiology; D005500:Follow-Up Studies; D018729:Fontan Procedure / Q000009:adverse effects*; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D017063:Outcome Assessment, Health Care
D000806:Angiotensin-Converting Enzyme Inhibitors; D009320:Atrial Natriuretic Factor