Sino-auricular block—standstill of the entire heart—is a rare type of arhythmia in the adult. It is usually the result of digitalis poisoning.1 Recently, however, a case due to salicylic acid has been described.2 It has occasionally been induced by vagal pressure3 in patients with normal rhythm and with paroxysmal tachycardia4 and has frequently been induced experimentally.5 The report of its occurrence as a clinical condition with accompanying graphic proof is exceedingly rare.5,6.
It has long been known that overindulgence in tobacco causes arhythmias, but their type has not been sufficiency studied by graphic methods to determine their exact nature. I have observed several cases of extrasystoles (usually auricular), one case of auricular flutter and one of auricular fibrillation due to tobacco poisoning. As sinoauricular block has never been ascribed to this cause, the following two cases seem sufficiently noteworthy to