A case of sick sinus syndrome in primary systemic amyloidosis.

A case of sick sinus syndrome due to primary systemic amyloidosis which involved mainly the heart and lungs is presented. The electrocardiogram showed various changes; low voltage, bradyarrhythmia with junctional escape beats, paroxysmal atrial tachyarrhythmia that terminates abruptly with subsequent long asystole, junctional rhythm from different origins and complete right bundle branch block which appeared at shorter and longer diastolic intervals. Histological examination showed an extensive amyloid infiltration in the upper parts of the conduction system, with major damage in the sinus node and also elsewhere in the heart. The patient died despite pacemaker implantation.