ABSTRACT
The effect of the autonomic nerves on the transmural dispersion of ventricular repolarization in intact canine was investigated. By using the monophasic action potential (MAP) recording technique, monophasic action potentials (MAPs) of the epicardium (Epi), midmyocardium (Mid) and endocardium (Endo) were recorded simultaneously by specially designed plunge-needle electrodes at the left ventricular free wall in 12 open-chest dogs. MAPD90 and transmural dispersion of repolarization among three myocardial layers as well as the incidence of the EAD before autonomic nervous stimulation and during autonomic nervous stimulation were compared. The results showed that the MAPD90 of Epi, Mid and Endo before autonomic nervous stimulation were 278 +/- 11 ms, 316 +/- 16 ms and 270 +/- 12 ms respectively, the MAPD90 of Mid was significantly longer than that of Epi or Endo (P<0.01). MAPD90 of Epi, Mid and Endo were shortened by 19 +/- 4 ms, 45 +/- 6 ms, 18 +/- 3 ms respectively during sympathetic stimulation. Compared with that of the control, the transmural dispersion of repolarization during sympathetic stimulation was shortened from 44 +/- 4 ms to 15 +/- 3 ms (P<0.01), but early afterdepolarizations were elicited in the Mid of 5 dogs (41%) during sympathetic stimulation. Parasympathetic stimulation did not significantly affect the MAPD90 in the three layers. It is concluded that there is the transmural dispersion of ventricular repolarization in intact canine. Sympathetic stimulation can reduce transmural dispersion of repolarization, but it can produce early afterdepolarizations in the Mid. Parasympathetic stimulation does not significantly affect the transmural dispersion of ventricular repolarization.
Subject(s)
Action Potentials/physiology , Autonomic Nervous System/physiology , Electric Stimulation , Electrocardiography , Electrodes , Endocardium/innervation , Endocardium/physiology , Heart Ventricles/innervation , Heart Ventricles/physiology , Myocardium/cytology , Neuromuscular Junction , Pericardium/innervation , Pericardium/physiologyABSTRACT
El mapeo endocárdico por catéter de la aurícula derecha durante ritmo sinusal en pacientes con fibrilación auricular paroxística ha permitido registrar electrogramas auriculares locales anormalmente prolongados y fraccionados. Un electrograma auricular anormalmente prolongado y fraccionado refleja una actividad eléctrica local desincronizada e inhomogénea, relacionada con una conducción retardada, no uniforme y anisotrópica, a través de un miocardio auricular patológico. Por los tanto, estos electorgramas auriculares anormales indican zonas con histología patológica y conducción alterada, donde es factible originar las arritmias por reentrada. El mapeo endocárdico auricular ha proporcionado una mayor comprensión del sustrato electrofisiológico de la fibrilación auricular. La detección de electrogramas anormales identifica a un grupo de pacientes con vulnerabilidad auricular aumentada y con incidencia significativamente mayor de episodios espontáneos o inducidos de fibrilación auricular