Emergency situations in sinus node dysfunction.

Sinus node dysfunction may produce in some cases life threatening medical emergencies. From 138 patients with sinus node dysfunction followed up in our department, we present 8 cases in which emergency situations required special therapeutical approaches (precordial thump, atrial or ventricular pacing, permanent pacemaker implantation). These situations appeared spontaneously, during the investigation procedures or after conversion of atrial fibrillation, performed for therapeutic purposes, when this arrhythmia concealed a sinus node dysfunction. The tachy-brady-arrhythmia could be influenced only by the implantation of a permanent pacemaker.

Sinoatrial node electrical activity recording through intracavitary leads.

Electrical activity of the sinoatrial node was recorded on bipolar intracavitary leads at superior vena caval-right atrial junction in ten patients. These recordings may be important for practical purposes, but they still have many limitations concerning the amount of the atrial potentials which can be recorded together with sinoatrial potential.

Transesophageal pacing technique in the estimation of sinus node function.

A personal noninvasive transesophageal pacing technique for the estimation of sinus node function is presented. With a pacemaker device and an esophageal pentapolar catheter, using a correction factor for the left atrial site of stimulation, it is possible to calculate the sinus node recovery time, sinoatrial conduction time and sinus node effective refractory period, before and after autonomic blockade as accurately as by the intracavitary technique.

[Increased atrial refractoriness: an explanation for the rarity of atrial arrhythmias in chronic cor pulmonale (author's transl)]. / L'aumento della refrattarieta' atriale: una spiegazione della rarita' delle aritmie atriali nel cuore polmonare cronico

Right atrial monophasic action potential was recorded using a suction electrode catheter in 20 patients with chronic cor pulmonale. The duration of right atrial monophasic action potential was recorded using suction electrode catheter in 20 patients with chronic corpulmonale. The duration of right atrial monophasic action potential was 397 +/- 17 msec, longer than the normal value of 325 +/- 37 msec found in 30 normal subjects. The conclusion of our work is that the long right atrial monophasic action potential duration may explain the sinus rhythm stability and the rarity of atrial arrhythmias in chronic cor pulmonale.

Experimental validation of sino-atrial conduction time using sinus node potential recording, right and left atrial continuous pacing method.

In an experimental study indirect sino-atrial conduction time (SACT) was measured, using continuous pacing method from right and left atrial sites, and compared with direct SACT obtained from sinus node potential recording, all the determination being done before and after autonomic blockade. The distance between the two sites of stimulation may be taken into account as a correction factor for SACT determination. The SACT obtained with sinus node potential technique is the same as the indirect SACT after autonomic blockade. These findings are valuable for SACT determination with transesophageal pacing method. Left atrial pacing, thus transesophageal pacing, is a valuable method in estimating the SACT, but a time correction and autonomic blockade is required in order to obtain a real value, eliminating the extrinsic influences.