Advanced Cardiac Physiology

Course overview

Objectives Identify the key components of the cardiac electrical system Describe the flow of electrical impulses through the heart Explain the origin of basic cardiac arrhythmias List the components of an ECG Content Information Covered II Physiology 1 Cardiac cycle 1 Consists of systole and diastole of atria and ventricles 2 Cycle occurs in about 0.8 seconds and 70 to 80 cycles per minute on average 3 Events that occur in one cardiac cycle a Atrial systole 1 Atrioventricular valves open and semilunar valves closed 2 Ventricles relaxed 3 Preceded by P wave on ECG b Isovolumetric contraction 1 Occurs between the start of ventricular systole and opening of semilunar valves 2 Ventricular volume remains constant 3 Onset coincides with R wave on ECG 4 First heart sound S1 a Caused by ventricular contraction and closure of cuspid valves b Lubb sound c Ejection phase Initial short rapid ejection followed by a longer phase of reduced ejection 1 Residual volume of blood remains in ventricles following ejection phase 2 Residual volume increases in states of heart failure d Isovolumetric relaxation 1 Period between closure of semilunar valves and opening of atrioventricular valves 2 Ventricles are relaxing 3 Second heart sound S2 a Caused by closure of semilunar valves b Dubb sound e Rapid ventricular filling f Reduced ventricular filling diastasis 2 Cardiac output 1 Heart rate times stroke volume Starling law Contractility