Sinus node disease (SND) has caused many controversies about the appropriate stimulation mode. We compared the advantages and disadvantages of VVI, AAI, DDD, and DDI mode. In an additional study, left ventricular function at rest (R) and during exercise (E) was investigated in dual chamber and ventricular stimulation mode with a stimulation rate of 70 ppm (R) and 110 ppm (E). A total of 223 patients (pts) was investigated (67 AAI, 87 VVI, 69 DDI). Hemodynamic disadvantages in VVI mode resulted in a 55% actuarial incidence of atrial fibrillation after five years. In AAI mode, we found another 25% complication rate due to impaired AV conduction (n = 9) or a bradyarrhythmia (n = 6) with slow ventricular response. DDI mode implies the possibility of sustaining a pacemaker mediated tachycardia. Single ventricular stimulation with a high stimulation rate (110 ppm) under E showed a worse left ventricular performance as compared to dual chamber stimulation. DDI mode shows none of the aforementioned disadvantages. To sum it up: Until a dual chamber rate responsive pacemaker becomes available, the DDI mode represents the best stimulation mode for patients with a SND.

SUMMARYRecurrence of a left atrial myxoma 6 years after the initial resection is reported. This, to our knowledge, is the second such case, and it emphasizes the need for a complete resection of the underlying atrial septum or atrial wall in cases of myxoma. Additional Indexing Words: Intracardiac tumors EmbolismYXOMA is an infrequent but important LYE intracardiac lesion which occurs most often in the left atrium. Although it has been suggested that atrial myxomas merely represent degenerated thrombi, evidence strongly favors a neoplastic origin.1Since the first successful removal of an intracardiac myxoma in 1955,2 numerous reports dealing with surgical resection of these tumors have appeared in the literature.39 In 1966, Newman and associates3 reviewed 58 attempted excisions of left atrial myxomas and reported no recurrence, and Firor's group4 reported a 5 to 10-year follow-up of their three operative cases with no reappearance of the tumor. They concluded that simple excision of atrial myxomas was adequate and that a resection of the adjacent atrial septum or wall was unnecessary. Similar opinions have been expressed by others,5' " based on the absence of recurrence and a lack of invasion of the myxoma beyond the elastic fibers of the second endothelial layer.We recently had the opportunity to study a patient in whom a left atrial myxoma

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