MEDI111 Lecture 7: CARDIOVASCULAR 2
6 Aug 2018
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Heart physiology: sequence of excitation: sinoatrial (sa) node (pacemaker, generates impulses at 75 times p/min, depolarizes faster than any part of the myocardium, atrioventricular (av) node, delays impulses by approx. * rate of depolarization decreases due to decreased rhr as you travel down the conduction pathway. Recording from an ecg: record from several leads to look at the heart from several different directions, 12 lead ecg. Chest leads: action potentials are taken from each surface. Standard approach to reading an ecg includes in this order: examining the rate, examining the rhythm, examining the axis, intervals and segments, examining everything else. Relationship between the squares on ecg paper and time: here, there is one qrs complex per second, so the heart rate is 60 bpm. Rhythm: part of the heart which is controlling the activation sequence. Types of rhythm: sinus rhythm, atrial fibrillation, atrial flutter, multifocal atrial tachycardia.
