Caudocranial conduction in the left auricle in nodal rhythm and in nodal ectopic beats.

As we described elsewhere (Wenger et al., 1950 and 1952) the pattern of aesophageal leads, as registered at various heights above the diaphragm, gives us the chance of drawing conclusions about the conduction in the left auricle. CEsophageal P waves at auricular levels contain well defined intrinsicoid deflections (Brown, 1936; Neuman, 1951; Schwartz, 1947; Wenger, 1947) and the time of their appearance measures the moment when the activation wave passes under the electrode. This is usually in very close relationship to the posterior wall of the left auricle, because the distance between auricle and cesophagus usually does not exceed a few millimetres. The theory of Lewis (1925) that the intrinsic deflections correspond to the time when activation passes the electrode has been attacked by various authors. Recent experimental findings, however, speak in favour of the opinion, that it is not inaccurate to use the intrinsicoid deflections in both cesophageal and intracardiac leads as an indication of the time of arrival of the process of activation under the electrode (Groedel et al., 1948; Sodi-Pallares et al., 1950; Wilson et al., 1947). We measure the interval from the beginning of the intrinsicoid deflection (i) to the QRS complex and call this distance i-R interval. Normally this interval (it may also bring into correlation the P-R interval in form of the quotient P-R/i-R) is of about the same length in all aesophageal auricular leads (Deutsch et al., 1949; Wenger, 1947 and 1952). This speaks in favour of the assumption that conduction takes place normally in a transverse direction from right to left. From this we conclude, that normally-as it is also known from animal experiments (Lewis, 1925)-the activation reaches the left auricle, coming over from the right auricle, at various levels of the posterior wall at more or less the same time, If we sketch these facts in form of an atriodiagram, we get a more or less vertical curve; on the horizontal line of the diagram the i-R intervals are recorded and in the vertical direction the distances of the cesophageal electrode from the diaphragm are shown (Fig. 1, lines b and d). In cases of nodal rhythm or nodal ectopic beats it is a priori questionable if the retrograde stimulus is using the normal pathways that conduct the normal stimulus from the right auricle to the A-V node, in the reversed direction. If this should be the case, the activation could reach the left auricle at its inferior part and continue its caudocranial course in the auricle, or it could use the same pathways from right to left as in sinus rhythm. In this case the i-R intervals at various heights of the cesophageal electrocardiogram would be more or less equal and the atriodiagram would show a normal pattern. In the other case (of caudocranial conduction through the left auricle) the i-R intervals would be registered earlier in deeper, and gradually later in higher, oesophageal leads at auricular levels. To establish this we investigated two cases of nodal rhythm and three cases of nodal ectopic beats by means of cesophageal electrocardiography.