Objectives 1. Discuss heart sounds 2. Describe the major types of cardiac valve disorders 3. Explain how a myocardial infarction might occur. 4. Describe the major types of cardiac dysrhythmia. 5. List and describe possible causes of heart failure.

Heart Sounds Two distinct sounds can be heard when listening to the heart – “lub dup” “lub” – caused by vibration and abrupt closure of the AV valves as the ventricle contracts This sound is of a longer duration and lower pitch than is the second sound. “dup” – closing of the semilunar valves

Valve Disorders Incompetent valves – leak Stenosed valves – narrower than normal Rheumatic heart disease – inflammation of cardiac valves and other tissues Mitral valve prolapse (MVP) – bicuspid valve flaps extend into left atrium causing incompetence

Heart Attack A myocardial infarction may result from occlusion or blockage of the left coronary artery

Cardiac Dysrhythmia Heart block – AV node block Bradycardia – slow heart rhythm (below 60 beats per minute); slight bradycardia is normal during sleep; abnormal caused from improper autonomic nervous control of the heart or a damaged SA node

Tachycardia – rapid heart rhythm (over 100 beats per minute); normal during exercise or stress response; abnormal results from improper autonomic control of the heart, blood loss or shock, action of drugs and toxins, fever, et al Sinus dysrhythmia – variation in heart rate during breathing cycle

Extrasystoles Frequent premature contractions Can lead to fibrillation – cardiac muscle fibers contract out of step with each other Ventricular fibrillation – immediately life- threatening

Heart Failure Cardiomyopathy – disease of the myocardial tissue, reduces pumping effectiveness Dysrhythmias can impair pumping effectiveness Congestive heart failure – left heart failure; decreases pumping pressure in the systemic circulation (portions become congested with fluids)