CARDIAC CARDIAC ARRYTHMIASARRYTHMIAS

Akmal Abbasi, M.D.Akmal Abbasi, M.D.

They are all bipolar (i.e., they detect a change in electric potential between two points) and detect an electrical potential change in the frontal plane. Lead I is between the right arm and left arm electrodes, the left arm being positive. Lead II is between the right arm and left leg electrodes, the left leg being positive. Lead III is between the left arm and left leg electrodes, the left leg again being positive.

EKG Standard Leads

Einthoven’s triangle

The same three leads that form the standard leads also form the three unipolar leads known as the augmented leads. These three leads are referred to as aVR (right arm), aVL (left arm) and aVF (left leg) and also record a change in electric potential in the frontal plane.

EKG Augmented Limb Leads

EKG Precordial Leads

These six unipolar leads, each in a different position on the chest, record the electric potential changes in the heart in a cross sectional plane. Each lead records the electrical variations that occur directly under the electrode.

EKG paper is a grid where time is measured along the horizontal axis. Each small square is 1 mm in length and represents 0.04 seconds. Each larger square is 5 mm in length and represents 0.2 seconds. Voltage is measured along the vertical axis.10 mm is equal to 1mV in voltage. The diagram below illustrates the configuration of EKG graph paper and whereto measure the components of the EKG wave form

Heart rate can be easily calculated from the EKG strip:When the rhythm is regular, the heart rate is 300 dividedby the number of large squares between the QRS complexes.

For example, if there are 4 large squares between regular QRS complexes, the heart rate is 75 (300/4=75).

The second method can be used with an irregular rhythm to estimate the rate. Count the number of R waves in a 6 second strip and multiply by 10.

For example, if there are 7 R waves in a 6 second strip, the heart rate is 70 (7x10=70).

P waveIndicates atrial depolarization, or contraction of the atrium. Normal duration is not longer than 0.11 seconds (less than 3 small squares) Amplitude (height) is no more than 3 mm No notching or peaking QRS complexIndicates ventricular depolarization, or contraction of the ventricles. Normally not longer than .10 seconds in duration Amplitude is not less than 5 mm in lead II or 9 mm in V3 and V4 R waves are deflected positively and the Q and S waves are negative

ST segmentIndicates early ventricular repolarization Normally not depressed more than 0.5 mm May be elevated slightly in some leads (no more than 1 mm) PR intervalIndicates AV conduction time Duration time is 0.12 to 0.20 seconds QT intervalIndicates repolarization time General rule: duration is less than half the preceding R-R interval

T waveIndicates ventricular repolarization Not more that 5 mm in amplitude in standard leads and 10 mm in precordial leads Rounded and asymmetrical

Normal Sinus Rhythm (NSR)Normal Sinus Rhythm (NSR)

                                                                                                                                                                                                        

DescriptionDescriptionThis is the normal heart rhythm. It originates in the SA node and This is the normal heart rhythm. It originates in the SA node and follows the appropriate conduction pathways. The rate is normal, and follows the appropriate conduction pathways. The rate is normal, and the rhythm is regular. Every beat has a P wave, and every P wave is the rhythm is regular. Every beat has a P wave, and every P wave is followed by a ventricular response.followed by a ventricular response.

EKG CriteriaEKG CriteriaRate:Rate: 60-100 bpm. 60-100 bpm.Rhythm:Rhythm: Regular. A normal variant called Sinus Arrythmia changes Regular. A normal variant called Sinus Arrythmia changes rhythm in response to respiration. This is seen most often in young rhythm in response to respiration. This is seen most often in young healthy people. healthy people. Pacemaker:Pacemaker: Each beat originates in the SA node. Each beat originates in the SA node.P wave:P wave: look the same, all originate from the same locus (SA node) look the same, all originate from the same locus (SA node)PRI:PRI: 120-200 msec 120-200 msecQRS:QRS: 80-120 msec, narrow unless effected by underlying anomoly 80-120 msec, narrow unless effected by underlying anomoly

SINUS BRADYCARDIASINUS BRADYCARDIA                                                                                                                                                                                                                      

DescriptionDescriptionSinus bradycardia originates in the SA node. It has reduced rate Sinus bradycardia originates in the SA node. It has reduced rate generally from a reduction in sympathetic input, or excessive vagal generally from a reduction in sympathetic input, or excessive vagal (parasympathetic) tone. This rhythm may accompany inferior MI's, (parasympathetic) tone. This rhythm may accompany inferior MI's, hypoxia, hypothermia, or drug reactions. At moderately slow rates, hypoxia, hypothermia, or drug reactions. At moderately slow rates, the patient may be asymptomatic. At slower rates, they may become the patient may be asymptomatic. At slower rates, they may become hypotensive and present with symptoms consistant with decreased hypotensive and present with symptoms consistant with decreased perfusion: dizziness, syncope, shock like signs and symptoms. perfusion: dizziness, syncope, shock like signs and symptoms. Treatment is aimed at increasing the heart rate. Therapies include Treatment is aimed at increasing the heart rate. Therapies include atropine, transcutaneous and transvenous pacing, epinephrine, atropine, transcutaneous and transvenous pacing, epinephrine, dopamine, isoproterenol.dopamine, isoproterenol.

EKG CriteriaEKG CriteriaRate: Rate: <60 bpm.<60 bpm.Rhythm: Rhythm: Regular generally.Regular generally.Pacemaker: Pacemaker: SA nodeSA nodeP wave: P wave: Present, all originating from SA node, all look the same.Present, all originating from SA node, all look the same.PRI: PRI: <200 msec, and constant.<200 msec, and constant.QRS: QRS: Normal, 80-120 msec.Normal, 80-120 msec.

SINUS TACHYCARDIASINUS TACHYCARDIA

                                                                                                                                                                                                        

DescriptionDescriptionThis arrythmia originates from the SA node. It is defined as a sinus This arrythmia originates from the SA node. It is defined as a sinus rhythm exceeding 100 bpm. Sinus tach is a normal rhythm which rhythm exceeding 100 bpm. Sinus tach is a normal rhythm which occurs in response to increased oxygen demand. This occurs with occurs in response to increased oxygen demand. This occurs with exercise, infection, hypovolemia, hypoxia, myocardial infarct, and in exercise, infection, hypovolemia, hypoxia, myocardial infarct, and in response to stimulant drugs, The rate usually has a gradual onset and response to stimulant drugs, The rate usually has a gradual onset and elimination. Treatment is not usually needed, but is aimed at treating elimination. Treatment is not usually needed, but is aimed at treating the underlying condition.the underlying condition.

EKG CriteriaEKG CriteriaRate: Rate: >100 bpm.>100 bpm.Rhythm: Rhythm: Regular, generallyRegular, generally..Pacemaker: Pacemaker: SA nodeSA node..P wave: P wave: Present and normal, may be buried in T waves in rapid Present and normal, may be buried in T waves in rapid tracings.tracings.PRI: PRI: 120-200 msec., generally closer to 120 msec.120-200 msec., generally closer to 120 msec.QRS: QRS: Normal.Normal.

PREMATURE ATRIAL PREMATURE ATRIAL COMPLEXES(PAC)COMPLEXES(PAC)

                                                                                                                                                                                                                     

DescriptionDescriptionThese complexes originate in the atria. They often originate from These complexes originate in the atria. They often originate from ectopic pacemaker sites within the atria which results in an abnormal ectopic pacemaker sites within the atria which results in an abnormal P wave. The complex occurs before the normal beat is expected, P wave. The complex occurs before the normal beat is expected, hence the prematurity. It is followed by a pause. There are many hence the prematurity. It is followed by a pause. There are many causes including: increased sympathetic input, exogenous stimulants, causes including: increased sympathetic input, exogenous stimulants, drug interactions, AMI, cardiac ischemia, idiopathic. These complexes drug interactions, AMI, cardiac ischemia, idiopathic. These complexes can indicate increased automaticity. They may lead to re-entry can indicate increased automaticity. They may lead to re-entry rhythms.rhythms.

EKG CriteriaEKG CriteriaRate: Rate: Underlying rhythmUnderlying rhythm..Rhythm: Rhythm: Irregular with PACs.Irregular with PACs.Pacemaker: Pacemaker: Ectopic atrial pacemaker outside SA node.Ectopic atrial pacemaker outside SA node.P wave: P wave: Ectopic P wave present, generally different than normal SA Ectopic P wave present, generally different than normal SA P wave.P wave.PRI: PRI: Generall normal range 120-200 msec, but differ from underlying Generall normal range 120-200 msec, but differ from underlying rhythm.rhythm.QRS: QRS: Same as underlying rhythm.Same as underlying rhythm.

ATRIAL FIBRILLATIONATRIAL FIBRILLATION

                                                                                                                                                                                                                    

                                                                                                                                                                                                        

DescriptionDescriptionThis is the most common sustained cardiac arrhythmia. It is This is the most common sustained cardiac arrhythmia. It is characterized by an undulating baseline replacing P waves and an characterized by an undulating baseline replacing P waves and an irregularly irregular ventricular response. This arrhythmia occurs with irregularly irregular ventricular response. This arrhythmia occurs with hypertension, ischemic, mitral, myocardial and pericardi al disease, hypertension, ischemic, mitral, myocardial and pericardi al disease, thyrotoxicosis, aging and sometimes occurs in normals. Treatment thyrotoxicosis, aging and sometimes occurs in normals. Treatment includes anticoagulation, drugs to slow ventricular conduction and/or includes anticoagulation, drugs to slow ventricular conduction and/or cardioversioncardioversion

EKG CriteriaEKG CriteriaUndulating baseline replaces P wavesUndulating baseline replaces P wavesRhythm: Rhythm: Irregularly irregularIrregularly irregular

ATRIAL FLUTTERATRIAL FLUTTER

                                                                                                                                                                                                        

DescriptionDescriptionAtrial flutter is characterized by "sawtooth" atrial activity and a Atrial flutter is characterized by "sawtooth" atrial activity and a conduction ratio to the ventricles of 2:1 to 8:1. It is caused by a conduction ratio to the ventricles of 2:1 to 8:1. It is caused by a reentrant circuit located in the right atrium. It may occur when the reentrant circuit located in the right atrium. It may occur when the atria are enlar ged in chronic obstructive lung disease, mitral or atria are enlar ged in chronic obstructive lung disease, mitral or tricuspid disease, pericarditis or post-operatively. Definitive tricuspid disease, pericarditis or post-operatively. Definitive treatment is direct-current cardioversion, surgical or catheter treatment is direct-current cardioversion, surgical or catheter ablation. ablation.

EKG CriteriaEKG CriteriaRate: Rate: 250 - 350 bpm (atrium)250 - 350 bpm (atrium)Rhythm: Rhythm: Atrial rate regular, ventricular conduction 2:1 to 8:1Atrial rate regular, ventricular conduction 2:1 to 8:1Pacemaker: Pacemaker: Reentrant circuit rhythm located in the right atriumReentrant circuit rhythm located in the right atriumP wave: P wave: Saw-tooth or picket fenceSaw-tooth or picket fencePRI: PRI: Constant onsetConstant onset

SUPRAVENTRICULAR SUPRAVENTRICULAR TACHYCARDIA (SVT)TACHYCARDIA (SVT)

                                                                                                                                                                                                        

DescriptionDescriptionThere are several different types of SVT depending on the site of There are several different types of SVT depending on the site of reentry (accessory pathway, atrioventricular node or atrium). This reentry (accessory pathway, atrioventricular node or atrium). This rapid rhythm starts and stops suddenly. Treatment includes vagal rapid rhythm starts and stops suddenly. Treatment includes vagal maneuvers, antiarrhythmia medication, radio-frequency ablation or maneuvers, antiarrhythmia medication, radio-frequency ablation or surgical modification of site of reentry. surgical modification of site of reentry.

EKG CriteriaEKG CriteriaRate: Rate: 140 - 220 bpm140 - 220 bpmRhythm: Rhythm: RegularRegularPacemaker: Pacemaker: Reentry circuit Reentry circuit Accessory pathway:Accessory pathway: Normal or short (if down accessory pathway) Normal or short (if down accessory pathway)A-V nodal reentry:A-V nodal reentry: Hidden in or at end of QRS Hidden in or at end of QRSPRI: PRI: Depends on location of circuitDepends on location of circuitQRS: QRS: Normal if accessory pathway used - prolonged (>120 msec) Normal if accessory pathway used - prolonged (>120 msec) with delta wavewith delta wave

PREMATURE JUNCTIONAL PREMATURE JUNCTIONAL COMPLEXES (PJC)COMPLEXES (PJC)

                                                                                                                                                                                                        

DescriptionDescriptionThese premature complexes originate in the atrioventricular junction. These premature complexes originate in the atrioventricular junction. Retrograde conduction through the atria may cause an inverted P Retrograde conduction through the atria may cause an inverted P wave in Lead 2. Integrate conduction may be normal (<120 msec). wave in Lead 2. Integrate conduction may be normal (<120 msec). Common etiologies include ischemia, hypoxemia, valvular disease, Common etiologies include ischemia, hypoxemia, valvular disease, digitalis or normal variant.digitalis or normal variant.

EKG CriteriaEKG CriteriaRate: Rate: Underlying rhythmUnderlying rhythmRhythm: Rhythm: Irregular with PJC'sIrregular with PJC'sPacemaker: Pacemaker: Ectopic junctional pacemakerEctopic junctional pacemakerP wave: P wave: If present, negative in Lead 2If present, negative in Lead 2PRI: PRI: 120 msec or less120 msec or lessQRS: QRS: 80-120 msec, unless prolonged by aberrant conduction80-120 msec, unless prolonged by aberrant conduction

JUNCTIONAL RHYHTMJUNCTIONAL RHYHTM                                                                                                                                                                                                                      

DescriptionDescriptionAn escape beat serves as a protective mechanism when higher An escape beat serves as a protective mechanism when higher centers in the conducting system fail to fire. Junctional escapes are centers in the conducting system fail to fire. Junctional escapes are recognized by their unchanged or only slightly changed QRS complex recognized by their unchanged or only slightly changed QRS complex ending a cardiac cycle longer than the dominant cycle. This rhythm ending a cardiac cycle longer than the dominant cycle. This rhythm occurs with increased vagal tone to the sinoatrial node, hypoxemia, occurs with increased vagal tone to the sinoatrial node, hypoxemia, and digitalis toxicity.and digitalis toxicity.

EKG CriteriaEKG CriteriaRate: Rate: 40 - 60 bpm40 - 60 bpmRhythm: Rhythm: RegularRegularPacemaker: Pacemaker: Atrioventricular junctionAtrioventricular junctionP wave: P wave: If present, negative in lead 2If present, negative in lead 2PRI: PRI: 120 msec or less120 msec or lessQRS: QRS: 80 -120 msec, unless prolonged by aberrant conduction80 -120 msec, unless prolonged by aberrant conduction

FIRST DEGREE AV BLOCKFIRST DEGREE AV BLOCK                                                                                                                                                                                                          

DescriptionDescriptionConduction disturbances are characterized as first degree, second Conduction disturbances are characterized as first degree, second degree Mobitz 1, second degree Mobitz II and complete heart block. degree Mobitz 1, second degree Mobitz II and complete heart block. The normal P-R interval is 120 - 200 msec. First degree AV block is a The normal P-R interval is 120 - 200 msec. First degree AV block is a constant and prolonged PR interval. Possible etiologies include insult constant and prolonged PR interval. Possible etiologies include insult to AV node, hypoxemia, myocardial infarction, digitalis toxicity, to AV node, hypoxemia, myocardial infarction, digitalis toxicity, ischemia of the conduction system and increased vagal tone but is ischemia of the conduction system and increased vagal tone but is also seen in normals.also seen in normals.

EKG CriteriaEKG CriteriaRhythm: Rhythm: RegularRegularPRI: PRI: >200 msec>200 msec

SECOND DEGREE AV SECOND DEGREE AV BLOCKBLOCK

MOBITZ I (WENKEBACH) MOBITZ I (WENKEBACH)                                                                                                                                                                                                                      

DescriptionDescriptionWenkebach is characterized by progressive delay at the AV node until Wenkebach is characterized by progressive delay at the AV node until the impulse is completely blocked. Etiologies are the same as cause the impulse is completely blocked. Etiologies are the same as cause first degree AV block and is also seen in normals. This conduction first degree AV block and is also seen in normals. This conduction abnormality does usually not progress to higher degree heart blocks.abnormality does usually not progress to higher degree heart blocks.

EKG CriteriaEKG CriteriaRhythm: Rhythm: IrregularIrregularPRI: PRI: Progressive lengthening of PRI until dropped beat. A clue to Progressive lengthening of PRI until dropped beat. A clue to Wenckebach is that the QRS's appear to occur in groups.Wenckebach is that the QRS's appear to occur in groups.

SECOND DEGREE AV BLOCKSECOND DEGREE AV BLOCK MOBITZ II MOBITZ II

                                                                                                                                                                                                                     

DescriptionDescriptionThis is a higher degree of conduction block then Mobitz I and may This is a higher degree of conduction block then Mobitz I and may progress to complete AV block. AV conduction appears normal until progress to complete AV block. AV conduction appears normal until suddenly there is no AV conduction following one P wave. This may suddenly there is no AV conduction following one P wave. This may occur in a pattern (every 2nd, 3rd or 4th complex) or may occur occur in a pattern (every 2nd, 3rd or 4th complex) or may occur randomly. This is intermittent block at the AV node and may progress randomly. This is intermittent block at the AV node and may progress to complete heart block.to complete heart block.

EKG CriteriaEKG CriteriaPRI: PRI: Constant on conducted complexes until a sudden block of AV Constant on conducted complexes until a sudden block of AV conduction. That is, a P wave is abruptly not followed by a QRSconduction. That is, a P wave is abruptly not followed by a QRS

THIRD DEGREE AV BLOCKTHIRD DEGREE AV BLOCK                                                                                                                                                                                                                      

DescriptionDescriptionThird degree AV block is total lack of conduction through the AV Third degree AV block is total lack of conduction through the AV node. The rate and the interval between the QRS depend upon the node. The rate and the interval between the QRS depend upon the origin of the escape mechanism. This conduction defect is dangerous origin of the escape mechanism. This conduction defect is dangerous and may progress to ventricular standstill. Treatment is an artificial and may progress to ventricular standstill. Treatment is an artificial ventricular pacemaker.ventricular pacemaker.

EKG CriteriaEKG CriteriaP wave: P wave: Independent P waves and QRS's with no relationship with Independent P waves and QRS's with no relationship with the two (AV dissociation)the two (AV dissociation)QRS: QRS: The QRS is normal in duration and slow (40-60 msec) with The QRS is normal in duration and slow (40-60 msec) with junctional escape rhythm. The QRS is wide (>120 msec) and slower junctional escape rhythm. The QRS is wide (>120 msec) and slower (30-40 bpm) with ventricular escape rhythm.(30-40 bpm) with ventricular escape rhythm.

PREMATURE VENTRICULAR CONTRACTIONS (PVC)PREMATURE VENTRICULAR CONTRACTIONS (PVC)                                                                                                                                                                                                                      

DescriptionDescriptionA PVC is a depolarization that arises in either ventricle before the next A PVC is a depolarization that arises in either ventricle before the next expected sinus beat. The normal sequence of depolarization is altered expected sinus beat. The normal sequence of depolarization is altered because the impulse originates in the ventricle. The two ventricules because the impulse originates in the ventricle. The two ventricules depolarize sequentially instead of simultaneously. Conduction moves more depolarize sequentially instead of simultaneously. Conduction moves more slowely than through the specialized conduction pathways, this results in a slowely than through the specialized conduction pathways, this results in a widened QRS complex (greater than 0.12 sec). PVCs may occur as isolated widened QRS complex (greater than 0.12 sec). PVCs may occur as isolated complexes or may occur in pairs, triplets, or in a repeating sequence with complexes or may occur in pairs, triplets, or in a repeating sequence with normal QRS complexes. Three or more PVCs in a row is considered a run of normal QRS complexes. Three or more PVCs in a row is considered a run of Ventricular Tachycardia. If it lasts for more than 30 seconds it is designated Ventricular Tachycardia. If it lasts for more than 30 seconds it is designated sustained VT. Treatment: Rarely treated unless symptomatic. PVCs may sustained VT. Treatment: Rarely treated unless symptomatic. PVCs may indicate acute mycardial ischemia requiring rapid intervention including indicate acute mycardial ischemia requiring rapid intervention including oxygen, NTG, morphine, thrombolytic. Treating with lidocaine will cease the oxygen, NTG, morphine, thrombolytic. Treating with lidocaine will cease the PVC, but won't address the ischemic cause.PVC, but won't address the ischemic cause.

EKG CriteriaEKG CriteriaRhythm:Rhythm: Irregular IrregularQRS:QRS: Is not normal looking. Broadened, greater than 0.12 seconds. P waves Is not normal looking. Broadened, greater than 0.12 seconds. P waves are usually obscured by the QRS, ST segment, or T wave of the OVC. The P are usually obscured by the QRS, ST segment, or T wave of the OVC. The P wave may sometimes be seen as notching during the ST segment or T wave.wave may sometimes be seen as notching during the ST segment or T wave.

BIGEMINY PVCsBIGEMINY PVCs

                                                                                                                                                                                                        

DescriptionDescriptionPVC's may occur in patterns. When each normal complex is PVC's may occur in patterns. When each normal complex is followed by a PVC forming groups of 2, the term "ventricular followed by a PVC forming groups of 2, the term "ventricular bigeminy" is used.bigeminy" is used.

EKG CriteriaEKG CriteriaQRS: QRS: Normal QRS complex followed by premature wide Normal QRS complex followed by premature wide bizarre complex (PVC) in patterns of 2bizarre complex (PVC) in patterns of 2

VENTRICULAR TACHYCARDIAVENTRICULAR TACHYCARDIA                                                                                                                                                                                                          

DescriptionDescriptionVentricular Tachycardia (VT) is defined as three or more beats of Ventricular Tachycardia (VT) is defined as three or more beats of ventricular origin in succession at a rate greater than 100 beats per ventricular origin in succession at a rate greater than 100 beats per minute. There are no normal (narrow) looking QRS complexes. minute. There are no normal (narrow) looking QRS complexes. Consequences of VT depend on accompanying myocardial Consequences of VT depend on accompanying myocardial dysfunction. It may be well tolerated or associated with life-dysfunction. It may be well tolerated or associated with life-threatening hemodynamic compromise. Treatment: If patient is threatening hemodynamic compromise. Treatment: If patient is stable, they are initially treated with lidocaine, procainamide, or stable, they are initially treated with lidocaine, procainamide, or bretylium tosylate. Hemodynamically unstable VT (with a pulse) is bretylium tosylate. Hemodynamically unstable VT (with a pulse) is cardioverted at 200J, 300J, 360J as needed. VT without a pulse is cardioverted at 200J, 300J, 360J as needed. VT without a pulse is treated like VF and defibrillated.treated like VF and defibrillated.

EKG Criteria EKG Criteria No normal looking QRS complexes, often bizzare with No normal looking QRS complexes, often bizzare with notching. Width of QRS>0.12 sec. ST segment and T wave are notching. Width of QRS>0.12 sec. ST segment and T wave are opposite polarity to the QRS. Sinus node may be depolarizing opposite polarity to the QRS. Sinus node may be depolarizing normally. There is usually complete AV dissociation. P waves are normally. There is usually complete AV dissociation. P waves are sometimes seen between QRS complexes. They have no impact on sometimes seen between QRS complexes. They have no impact on the QRS complexes.the QRS complexes.Rate:Rate: Generally 100 to 220 bpm Generally 100 to 220 bpmRhythm: Rhythm: Generally regular, on occassion can be modestly irregular.Generally regular, on occassion can be modestly irregular.

VENTRICULAR FIBRILLATIONVENTRICULAR FIBRILLATION                                                                                                                                                                              

DescriptionDescriptionVentricular Fibrillation is a rhythm in which multiple areas within the Ventricular Fibrillation is a rhythm in which multiple areas within the ventricles display marked variation in depolarization and ventricles display marked variation in depolarization and repolarization. There is no organized depolarization, therefore the repolarization. There is no organized depolarization, therefore the ventricles do not contract as a unit. The myocardium is quivering ventricles do not contract as a unit. The myocardium is quivering when visualized grossly. There is no cardiac output. This is the most when visualized grossly. There is no cardiac output. This is the most common arrythmia seen in cardiac arrest from ischemia or infarction. common arrythmia seen in cardiac arrest from ischemia or infarction. The rhythm is described as coarse or fine VF. Coarse VF indicates The rhythm is described as coarse or fine VF. Coarse VF indicates recent onset of VF. Prolonged delay without defibrillation results in recent onset of VF. Prolonged delay without defibrillation results in fine VF and eventually asysyole. Resuscitation becomes more difficult fine VF and eventually asysyole. Resuscitation becomes more difficult as VF becomes finer. Treatment is always immediate unsynchronized as VF becomes finer. Treatment is always immediate unsynchronized defibrillation at 200J, 300J, 360J for adult patients.defibrillation at 200J, 300J, 360J for adult patients.

EKG CriteriaEKG CriteriaRate:Rate: Very rapid, too disorganized to count. Very rapid, too disorganized to count.Rhythm:Rhythm: Irregular, waveform varies in size and shape Irregular, waveform varies in size and shapeNo normal QRS complexes.No normal QRS complexes.Absent ST segments, P waves, T waves.Absent ST segments, P waves, T waves.

ASYSTOLEASYSTOLE                                                                                                                                                                                                          

DescriptionDescriptionAsystole represents the total absence of ventricular electrical activity. Since Asystole represents the total absence of ventricular electrical activity. Since depolarization does not occur, there is no ventricular contraction. This may depolarization does not occur, there is no ventricular contraction. This may occur as a primary event in cardiac arrest, or it may follow VF or pulseless occur as a primary event in cardiac arrest, or it may follow VF or pulseless electrical activity (PEA). Ventricular asystole can occur also in patients with electrical activity (PEA). Ventricular asystole can occur also in patients with complete heart block in whom there is no excape pacemaker. VF may complete heart block in whom there is no excape pacemaker. VF may masquerade as asystole; it is best always to check two leads perpendicular to masquerade as asystole; it is best always to check two leads perpendicular to each other to make sure that asystole is not VF. Treatment for each each other to make sure that asystole is not VF. Treatment for each arrythmia is very different. Fine VF which may mimic asystole should be arrythmia is very different. Fine VF which may mimic asystole should be treated with defibrillation. But defibrillating asystole is potentially harmful. treated with defibrillation. But defibrillating asystole is potentially harmful. Treatment: Epinephrine and Atropine are administered. Consider causes: Treatment: Epinephrine and Atropine are administered. Consider causes: pulmonary embolism, acidosis, tension pneumothorax, cardiac tamponade, pulmonary embolism, acidosis, tension pneumothorax, cardiac tamponade, hyperkalemia, hypokalemia, hypoxia, hypothermia, overdose, myocardial hyperkalemia, hypokalemia, hypoxia, hypothermia, overdose, myocardial infarction. (Pneumonic: PATCH(4)-O-MIne.infarction. (Pneumonic: PATCH(4)-O-MIne.

EKG CriteriaEKG CriteriaComplete absence of ventricular electrical activity. Occasional P waves or Complete absence of ventricular electrical activity. Occasional P waves or erratic ventricular beats may be seen. These patients will be pulseless. erratic ventricular beats may be seen. These patients will be pulseless. Treatment must be immediate if the patient is to have any chance at Treatment must be immediate if the patient is to have any chance at resusctiation.resusctiation.Rate:Rate: None NoneRhythm:Rhythm: None None

MYOCARDIAL INFARCTION                                                                                                     

DescriptionPathologic Q waves indicate myocardial death. Infarction locations are determined by the presence of Q wave; Anterior: Q waves in leads V1, V4, I and AVL. Inferior: Q waves in leads II, III, AVF, Lateral: Q waves in leads V5-V6, I and AVL. Posterior: Tall R waves in leads V1-V2.

ST segment elevation may be present in an acute MI but also with Prinzmetal's angina, LV aneurysm, pericarditis or a normal variant. With MI, ST segment elevation resolves within days but pathologic Q waves may remain.

EKG CriteriaPathologic Q waves are >30 msec wide or 1/3 length of the QRS complex. ST segment elevation is >1mm above the isoelectric line. Leads involved will localize the area of the myocardium involved.

• wide QRS, more than 120 ms (3 small squares) • secondary R wave in lead V1 • other features include slurred S wave in lateral leads and T wave

changes in the septal leads

Right Bundle Branch Block

• left anterior hemiblock • QRS axis more left than -30 degrees • initial R wave in the inferior leads (II, III and aVF) • left ventricular hypertrophy • long PR interval (also called first degree heart block) • PR interval longer than 0.2 seconds • left atrial hypertrophy • M shaped P wave in lead II • P wave duration > 0.11 seconds • terminal negative component to the P wave in lead V1

Left Bundle Branch Block

• short PR interval, less than 3 small squares (120 ms) • slurred upstroke to the QRS indicating pre-excitation (delta wave) • broad QRS • secondary ST and T wave changes

Wolf-Parkinson-White syndrome