Heart Rhythms: Normal or Abnormal (Arrhythmias) Anatomy & Physiology L3

Electrical Conduction SA Node (sinoatrial) Group of specialized myocytes near Sup. Vena cava Create action potential Creates an action potential approx bpm Innervated by Brain stem Sympathetic: Increase HR Vagus: decrease HR AV node (atrioventricl.) “Decremental conduction” (AV delay = 0.01 sec) Prevents premature contraction of ventricles Alone, can create a beat approx 40 bpm NOT strong enough to sustain life

Interior anatomy of heart Bundle of His Collection of cardiac cells creating the AV node Conduct impulses along septum to the Purkinje fibers in walls of the ventricles Takes impulse about sec to travel to the ventricles Purkinje fibers: thin filaments Located on inner wall of endocardium Carry electrical impulse from SA and AV nodes Move from left to right

Normal sinus rhythm

Electrocardiogram (ECG or EKG) 12-lead (multi- angle)

Acute MI

Myocardial Infarction (heart attack) Mortality: 500K – 700K per year in US 1.3 million reported cases of MI 600 per 100K Complete obstruction of coronary artery(s) leading to portion of heart muscle to die Signs & Symptoms Persistent chest pain Tightness in chest Difficulty breathing Jaw, neck, shoulder pain (referred pain) Sweating

What do I Do? Recognize the signs Get immediate medical help BLS, Meds, Hospital Try to stabilize in the ER Time for “Dr Burke” Surgery: Angioplasty Use of a stent Coronary Bypass

TEST TIME! Good Luck! Anatomy of the Heart Pathway of blood flow Electrical conduction Common problems (ex; atherosclerosis, pulmonary embolism, coronary thrombosis) Myocardial Infarction and the treatment of Common ECG readings