L:10b - ECG Recordings and Heart Disease
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36 terms
Terms | Definitions |
|---|---|
 P wave |  depolarization of both atria - relationship between P and QRS helps distinguish various cardiac arrhythmias - shape and duration of P may indicate atrial enlargement |
| PR interval | atria to ventricular conduction time (through Bundle of His) - normal duration 0.12-2.0 sec - prolonged PR interval may indicate 1st degree block |
| QRS complex |  ventricular depolarization - normal duration 0.08-0.12 sec - its duration, amplitude, and morphology are useful in diagnosing cardiac arrhythmias, ventricular hypertrophy, MI, electrolyte derangement, etc - Q wave > 1/3 high of R wave, > 0.04 sec = abnormal (may represent MI) |
| ST segment | connects the QRS to the T wave - 0.08-0.12 sec |
| T wave |  repolarization/recovery of ventricles - interval from start of QRS to apex of T = ABSOLUTE REFRACTORY PERIOD |
| QT interval | - measured from start of QRS to end of T wave - normal QT = 0.40 sec - varies based on HR |
| U wave | thought to represent repolarization of papillary muscles and Purkinje fibers - occasionally seen after T wave - seen in hypokalemia and occasionally hypercalcemia and thyrotoxicosis - inverted U wave may be seen in myocardial ischemia or LV volume overload |
| sinus rhythm | - SA node is cardiac pacemaker, controlled by ANS --> PNS predominates (M2-r) - normal sinus rhythm is 60-100 bpm - depolarization triggers depolarization of atrial myocardium - conducts more slowly though AV node - conducts rapidly through HIS and purkinke fibers *look for P waves in V1, V2, lead II for rhythm - it is regular if each P wave has an R wave |
| AFib | no P waves |
| supraventricular tachycardia | QRS narrow no visible p waves > 150 |
| ventricular tachycardia | wide QRS no visible p waves |
| ischemic heart disease |  - occurs when blood supply to tissue is deficient + causes increased lactic acid from anaerobic metabolism - usually due to atherosclerosis in coronaries - often accompanied by angina pectoris - detectable by changes in S-T segment of ECG |
| mechanisms of arrhythmia production | 1. re-entry - refractory tissue reactivated due to conduction block, causes abnormal continious circuit, ex: pathways linking atria and ventricles in Wolff-Parkinson-White syndrome 2. abnormal pacemaker activity in non-conducting/conducting tissue, ex: ischemia 3. delayed after-depolarization - automatic depolarization of cardiac cell triggers ectopic beats, can be caused by drugs, ex: digoxin |
| vaughn williams classification of antiarrhythmic drugs | Class 1: block Na channels 1a. increase AP: quinidine, procainamide, dispyramide 1b. decrease AP: lidocaine, mexiletine, phenytoin 1c. flecainide, propafenone Class 2: beta blockers Class 3: prolong AP and RP: amiodarone, sotalol Class 4: ca channel blockers: verpramil |
| first degree av node block |  |
| second degree av node block |  |
| 3rd degree/complete av node block |  |
| right bundle branch block |  |
| left bundle branch block |  |
| left ventricular hypertrophy |  |
| right ventricular hypertrophy |  |
| angina |  |
| MI |  |
| sick sinus syndrome |  dysfunction in SA node causes - chronic and severe sinus bradycardia - sinus pauses - sinus arrhythmia - complete sinus arrest - atrial arrhythmia CAUSE - sa node fibrosis, atherosclerosis of SA artery, congenital heart disease, drugs, excessive vagal tone |
| tachycardia-bradycarida syndrome |  - variant of SSS, severe bradycardia alternates with paroxysmal tachycardias (usually Afib) - no prolonged pause following tachy |
| multifocal atrial tachycardia |  discrete P waves with at least 3 different morphologies, atrial HR>100bpm PP, PR, RR always vary |
| pre-excitation (WPW syndrome) |  accessory pathway of conduction = atypical sequence of depolarization WPW is most common: direct AV connection allows ventricles to depolarize while AP is still traveling through AV node - short PR interval - QRS prolongation - delta wave AV re-entrant Tachycardia (AVRT) - in pt's w/WPW, a re-entrant rhythm can be generated where AV node serves as one arm of re-entrant circuit and the accessory pathway as the other |
| a normal ecg |  - 5 large boxes = HR is 60 bmp |
| wolff-parkinson-white syndrome |  - long QRS - hr appears to be ~60 bpm - delta wave - short pr |
| atrial tachycardia |  HR~ 100 bpm heights are the same throughout |
| atrial flutter |  HR ~120 rhythm regualar long qrs |
| atrial fibrillation |  - wavey lines - no P waves in lead III? |
| ventricular tachycardia |  - wavy lines - slower in I than V4 |
| 2:1 atrial flutter w/pre-existent lbbb |  wide qrs w/block |
| vFib/vFib and dc shock (arrow) |  crazy fast zig zags high t waves |
| ecg conduction |  |
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