Sinoatrial-node entrance block.
D000328:Adult; D000368:Aged; D001145:Arrhythmias, Cardiac / Q000503:physiopathology; D006328:Cardiac Catheterization; D004562:Electrocardiography; D006325:Heart Atria / Q000503:physiopathology; D006327:Heart Block / Q000503:physiopathology*; D006329:Heart Conduction System / Q000503:physiopathology; D006801:Humans; D008297:Male; D008722:Methods; D008875:Middle Aged; D012849:Sinoatrial Node / Q000502:physiology / Q000503:physiopathology*