Electrophysiologic characteristics of the Crista terminalis and implications on atrial tachycardia in rabbits.

The objective of this study was to evaluate the electrophysiologic characteristics of Crista terminalis (CT) and their implication in the pathogenesis of atrial tachycardia in rabbits. For this purpose, 27 New Zealand rabbits were used. Using standard glass microelectrode technique, cellular action potentials (APs) of CT and pectinate muscle (PM) were recorded in normal Tyrode's perfusion and Tyrode's perfusion with 4 µM isoproterenol. Longitudinal conduction velocity (V(L)) and transverse conduction velocity (V(T)) of CT were measured. As our data show, CT tissue had a trend of spontaneous phase IV depolarization. Conduction anisotropy (V(L)/V(T)) of CT was 4.53 ± 0.91. The duration of the AP of CT was longer than that of PM cells. APD(20) and APD(90) for CT were 28.1 ± 3.5 and 145.3 ± 7.1 ms; and for PM cells were 21.8 ± 4.1 and 125.3 ± 6.3 ms, respectively (all P values < 0.01). The early and delayed action depolarizations were recorded after isoproterenol perfusion. A fast paroxysmal irregular rhythm was recorded which could be arrested by 0.1 mmol/l Isoptin. It was, therefore, concluded that the latent autorhythmicity, trigger activity, and conduction properties of CT might provide the electrophysiologic basis for the occurrence and sustenance of atrial arrhythmia.

The role of coronary sinus musculature on electrical conduction between left atrium and right atrium in isolated canine heart / 中华心血管病杂志

<p><b>OBJECTIVE</b>To investigate electrophysiological characteristics of the coronary sinus musculature and explore its role on electrical conduction between left atrium and right atrium in isolated canine heart.</p><p><b>METHOD</b>The electrical connections between coronary sinus, left atrium and right atrium were detected by programmed stimulation delivered at coronary sinus ostium, distal coronary sinus and lateral wall of left atrium in a Langendorff model of canine.</p><p><b>RESULTS</b>During stimulation delivered at coronary sinus ostium and distal coronary sinus, posterior wall of left atrium was firstly activated by electronic signal through coronary sinus musculature, the conduct time of coronary sinus ostium stimulation and distal coronary sinus stimulation were (44 +/- 21) ms and (41 +/- 15) ms, respectively. During stimulation delivered at lateral wall of left atrium, electronic signal was firstly observed in coronary sinus. During premature stimulation, conduction blockade of coronary sinus to left atrium was evidenced in parts of hearts, but electronic conduction of left atrium to right atrium remained stable. The ERP at the different stimulation sites of coronary sinus ostium and distal coronary sinus, posterior wall of left atrium were (122 +/- 19) ms, (114 +/- 12) ms (n = 3) and (107 +/- 17) ms (all P > 0.05).</p><p><b>CONCLUSION</b>A conduction way connecting left and right atria exists in coronary sinus which might play an important role on inducing and maintaining atrial arrhythmias under certain pathological conditions.</p>