Normal P wave Atrial depolarization 12 seconds in duration Amplitude should not exceed 2 5 mm Positive in lead II Negative in aVR T wave Ventricular repolarization Positive by the time a V3 and then stays that way Positive in lead II Negative in aVR QRS complex Ventricular depolarization 12 seconds in duration Positive deflection at V1 V1 shows rS V6 shows qR Rs Q wave 04 s Depth usually 1 3 of R wave except aVR normally have deep Q wave Right atrial enlargement Left atrial enlargement Right ventricular hypertrophy amplitude in 1st portion of P wave No change in duration Possible right axis deviation Tallest P wave may not appear in II but in III or aVF Terminal portion of P wave drops at least 1mm below isoelectric line at V1 in duration QRS negative in lead I right axis deviation No transition zone Strain ST segment depression and T wave inversion Increase in muscle mass caused by pressure overload QRS complex V1 Rs Enlargement Dilation chamber caused by volume overload Caused by lung disease Look at V1 and Lead II Enlargement Dilation chamber caused by volume overload Caused by mitral valve disease Look at V1 and Lead II Left ventricular hypertrophy QRS negative in lead I right axis deviation HUGE QRS complex Strain ST segment depression and T wave inversion short TS segment Originate in atria or AV node V6 rS Increase in muscle mass caused by pressure overload QRS complex V1 Rs V6 rS Sinus arrest or exit block Originate in atria or AV node Common in pts with severe lung disease No atrial depolarization Depolarization originates near AV node so usual patter of atrial depol Does not occur Like junctional escape but difference is that junctional premature cont occurs early Junctional escape happens later after SA node fails to fire Regular rhythm rate of 100 200 b min Warm up and cool down period in EKG Irregular rhythm rate of 100 to 200 b min Wandering atrial pacemaker P waves are asymmetrical and differ in shape Junctional escape No P wave Retrograde P wave Atrial premature contraction Supraventricular arrhythmia Junctional premature contraction Supraventricular arrhythmia Paroxysmal atrial Tachycardia PAT supraventricular arrhythmias Multifocal Atrial Tachycardia MAT supraventricular arrhythmias Contour of P wave different from normal one and also P wave introduces itself early Usually no P wave but sometimes retrograde P wave P waves are found before QRS complex way to distinguish b w fibrilation Shape of P wave and PQ interval will vary b c beats are usually conducted normally to ventricles the QRS complex is narrow b c beats are usually conducted normally to ventricles the QRS complex is narrow Choppy QRS complex diff distances b n R waves but P waves are found Irregularly irregular QRS complex in absence of discrete P waves different distances b n R waves Narrow QRS Atrial fibrilation supraventricular arrhythmias Paroxysmal Supraventricular tachycardia PSVT Sustained supraventricular arrhythmias Atrial flutter supraventricular arrhythmias identify at least 3 different P wave morphologies diagnosis No true P waves seen baseline flat Retrograde P waves can be seen in leads II or III Best chance look at V1 for pseudo R little blip in QRS representing superimposed p wave Often P waves so buried that cant be identified P waves occur at rate 250 to 350 b min Atrial depolarization happens so fast that P waves separated by base lines not seen AV node cant handle P waves can be Irregular squiggly AV node completely bomnarded could be 500 impulses min Multiple reentrant circuits Atrial rate 350 500 b min Rate b n 150 250 beats Regular Carotid massage can slow this Underllting pathology often present Onset sudden Initiated by premature supravent beat Termination just as sudden May be no underlying cardiac disease can occur in normal hearts Can be 2 P wave to 1 QRS 2 1 or 3 1 4 1 Can occur in normal hearts or pts w underlying cardiac pathology Regular saw toothed Atrial rate 250 350 b min Leads II and III can be prominent Single constant reentrant circuit Premature ventricular contractions PVC s Ventricular arrhythmia Ventricular tachycardia Ventricular arrhythmia Ventricular fibrilation Ventricular arrhythmia Accelerated idioventricular rhythm Ventricular arrhythmia Torsades De Pointes Ventricular arrhythmia different shapes Retrograde P often seen but more common to see no Pwave at all If PVC falls on T wave of previous beat called R on T phenomenon T wave vulnerable and if PVC falls her more likely to set off vent Tachycardia rule 4 QRS Complex wide and bizarre b c vent depol does not follow normal conduction pathways May not appear wide in all leads 3 or more wide and complex QRS complex s When 50 b min look closely for P waves to exclude a sinus bradycardia No P waves No true QRS complex QRS wide QRS complex spiral around baseline changing their axis and amplitude Prolonged QT interval could be from electrolyte disturbances or from acute MI or from pharmacological agents Result of prolonged vent Repol T wave Bigeminy one normal sinus beat to one PVC Trigeminy two normal sinus beats for every one PVC Usually followed by prolonged pause before next beat appears Slightly irregular Rate usually b n 120 and 200 May be uniform healed infarction or polymorphic acute coronary ischemia or infarction Preterminal event only seen when about to die Seen in sudden death Regular 50 100 b min When rate 50 b min its called idioventricular rhythm Run or three or more PVC s is called this Emergency presaging cardiac arrest No CO RESUSCITATION MUST BE PERFORMED AT ONCE Sometimes seen in acute infarction Rarely sustained does not progress to vent Fibrilation Unique form of vent Tachycardia usually seen in pts w prolonged QT interval QT interval beg of vent depolar to end of vent repolar 40 of cardiac cycle First degree AV block Conduction Block PR interval longer that 2 seconds Always QRS complex after P wave Second degree AV block Mobitz type I Wenckebach block Conduction Block Second degree block Mobitz type 2 Conduction Block Progressive lengthening of PR interval until one P wave fails to conduct through AV node Dropped beat without progressive lengthening of PR interval Third degree Complete heart block Conduction Block P waves appear at regular interval having nothing to do with QRS complex Right bundle branch block Left bundle branch block That P wave is not followed by a QRS complex No QRS complex after a P wave dropped beat QRS complex appear at regular interval having nothing to do with
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