More common with the elderly, the matrix of fibrous tissue around the SA nodeThe SA node, usually the dominant pacemaker, is located in the right atrium at the opening of the superior vena cava. The SA (sinoatrial) node is a clump of hundreds of specialized cardiac cells that have the ability to self-initiate... becomes denser, eventually affecting the ability of the SA node to transmit an impulse consistently to the atriaRight and left atria (1/3 volume and muscle mass of the ventricles) pump blood to the ventricles. Chambers and Layers of the Heart 1. Six Second ECG Guidebook (2012), T Barill, p. 190; characteristic signs include periods of sinus bradycardiaA cardiac rhythm that originates from the SA node with a rate less than 60/minute. sinus bradycardia, HR 56/min 1. Six Second ECG Guidebook (2012), T Barill, p. 104, 205 following by periods of sinus tachycardiaA cardiac rhythm that originates from the SA node with rates most often 101-180/minute. sinus tachycardia, HR 138/min 1. Six Second ECG Guidebook (2012), T Barill, p. 104, 206.
1. Six Second ECG GuidebookA Practice Guide to Basic and 12 Lead ECG Interpretation, written by Tracy Barill, 2012 Introduction The ability to correctly interpret an electrocardiogram (ECG), be it a simple six second strip or a 12 lead ECG, is a vital skill... (2012), T Barill, p. 205