Transcript ECG NOTES
Heart Anatomy The heart is a muscle The heart muscle is called MYOCARDIUM. It is involuntary – it pumps without us having to think about it! The inside layer of muscle is ENDOCARDIUM. The outside layer is EPICARDIUM. The membranous sac around the heart is the PERICARDIUM. Exterior anatomy of the heart Interior anatomy of the heart Heart Beat The average adult human’s heart rate is 60 to 100 beats per minute. Pumping Action When the ventricles are relaxed (filling with blood) this is called DIASTOLE. When the ventricles contract (pumping out blood) this is called SYSTOLE. ASYSTOLE occurs when the heart stops beating! ECG • Electrocardiogram • Also called EKG • Records the electrical current in the heart The way it works • • • • SA node fires Atria contract (P wave) AV node fires Signal travels through bundle of His and Purkinje fibers, and the ventricles contract (QRS complex) • Ventricles repolarize & prepare for next beat (T wave) Interior anatomy of the heart ECG Parts • P – Atrial depolarization (contraction) • QRS – Ventricular depolarization (contraction – BP systole) • T – Ventricular repolarization (rest – BP diastole) • U – Atrial repolarization (rest – BP diastole) ECG R to R interval • The time between the R waves on two consecutive heartbeats. Now some math! • If your heart beats 75 times per minute, how long is the R to R interval? Answer: 0.8 seconds. A normal heart rhythm is called… Normal sinus rhythm Sinus Rhythms – always have P wave followed by QRS • Normal Sinus Rhythm (NSR) rate is 60-100 and rhythm is regular Other types of rhythms are atrial and ventricular These indicate a problem with the electrical system of the heart AND vary in level of seriousness Atrial fibrillation is a common disorder of the conduction system it occurs when the atria get out of rhythm and shake instead of pumping • Atrial Fibrillation Ventricular Rhythms are generally more serious and can result in lifethreatening rhythms in which the heart does not pump blood effectively Ventricular fibrillation (V Fib) • Rate is too irregular to count. Cannot identify any par of the waveform. Asystole – Straight line • No heart activity is seen. • Clinical death is present. • Will become biological death if lasts longer than 4-6 minutes. You will not have to recognize rhythms on the test • If you are in the diagnostic imaging class you have had some experience with these • If not, take it next year if you can! • You will also get to see MY ECG later • You will only need what’s on the notetaking guide! Valve problems • Valves close at appropriate times to keep blood from flowing back into the area from which it came. • Sometimes valves can stop working properly and clotting can occur. • These problems are called regurgitation, prolapse, or stenosis. It’s a heart attack! • A heart attack is when blood doesn’t get to the heart muscle. • Without blood, the heart muscle will die. • A heart attack is also called a MYOCARDIAL INFARCTION. Pathology of MI • Plaque builds up slowly (frequently LAD) • Sudden blockage occurs and muscle and nerve tissue distal begin to malfunction and then die • Abnormal activity and contractions • Leads to V Fib/Asystole • Scar tissue may form during healing and cause disrhythmias. Coronary Vessels Plaque Myocardial Infarction • Heart Attack MI Treatment • • • • • Aimed at restoring coronary blood flow Angioplasty and stent placement Coronary artery by-pass graft (CABG) Anticoagulants: heparin and coumadin Aspirin (ASA): anticoagulant and antiinflammatory agent Pathology of CHF • • • • Congestive heart failure Damaged valves or ventricular muscle Heart cannot completely empty Right failure – blood backs up in legs (pitting edema, 1+ to 4+) • Left failure – blood backs up in lungs (pulmonary edema) • Cardiotonic – lanoxin, digoxin (not if pulse < 60) • Diuretic - lasix CHF • Heart Failure Test Your Knowledge • • • • Label the Parts of Your Heart Label Your Heart's Electrical System Name Your Blood Vessels Define Common Heart Problems