ventricular tachycardia

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Ventricular arrythmias

Ventricular Tachycardia Dr. Akshay Chincholi

Ventricular TachycardiaArrhythmia of three or more consecutive complexes in duration originating from the ventricles at a rate of 100 bpmAccounts for up to 80% of Wide complex tachycardiaNonsustained VTThree or more beats in duration, terminating spontaneously in less than 30 s.Sustained VTVT greater than 30 s in duration and/or requiring termination due to hemodynamic compromise in less than 30 s.

Rate 100 to 250 / minRhythm- Regular / slightly irregular QRS durationRBBB >140msLBBB >160msQRS Axis 20% of VTs have a northwest axis (sensitivity 20%, specificity 96%)Right axis deviation with LBBB suggests VT(sensitivity 20%, specificity 97%)In patients with history of MI, axis deviation greater than 40 from the baseline ECG

QRS Concordance A concordant pattern is defined as predominant QRS deflection, which is either all positive or all negative across the precordial leads V1 to V6occurs in only 15% of VTs with specificity of >90%positive concordance seen in 18% of VTs with RBBB-type pattern12% of LBBB-type VTs showed negative concordance

AV dissociation Complete AV dissociation - 20% to 50%1:1 VA relation - 30%2:1 retrograde (VA) conduction and retrograde Wenckebach block - 15%20%sensitivity of 20%50%, with specificity approaching 100%

Capture and Fusion QRS ComplexesA capture complex occurs when a supraventricular impulse propagates through the normal HPS system between VT QRS complexes and excites both ventricles completelyCapture complexes are narrow QRS complexes similar to sinus complexesFused QRS complexes are those in which the QRS is a combination of 2 sources of ventricular activation (supraventricular and ventricular during VT)

QRS mprphologyIn Precordial leadsConcordantNo R/S patternOnset of R to nadir longer than 100 msecRBBB patternqR, Rs or Rr in V1broad R (>40 ms) in lead V1rS complex in lead V6LBBB patternr in V1 longer than 30 msecR to nadir of S in V1 greater than 60 msecNotching in the downstroke of the S waveqR or qS in V6Other specific patterns in V1Rs and W configuration in V1

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No RS Pattern

KINDWALL CRITERIA

KINDWALL CRITERIA

MILLER CRITERIA

Idiopathic Ventricular TachycardiaRefers to VT of unknown cause that occurs in the absence of structural heart disease or transient or reversible arrhythmogenic factors (e.g., electrolyte disorders, myocardial ischemia).Based on the location of the VTOutflow tract tachycardiaAnnular VTFascicular VT (left septal VT)

Outflow Tract TachycardiaAccounts for 50% of idiopathic VT and 10% of all VTsTypes RVOT VT (80%)LVOT VT (20%)Occurs in young to middle age patients Mechanism cAMP mediated delayed afterdepolarizations

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RVOT VTLBBB pattern + Inferior axis R wave transition at or later than V3LVOT VT 2 patterns on ECGRBBB pattern + Inferior axis ( aortomitral continuity) LBBB pattern + Inferior axis + R wave transition V2 (basal aspect of superior LV septum)The prognosis for most patients RV/LV OT VT is good.Vagal maneuvers, Beta blockers, verapamil & adenosine can terminate the VTexercise, stress,caffeine, isoproterenol infusion, and rapid or premature stimulation often initiate or perpetuate the tachycardia.

RVOT VTLBBB pattern and Inferior axis in frontal plane The precordial R wave transition occurs at or later than V3

LVOT VTLBBB pattern + Inferior axis - R wave transition occuring in V1 to V2 - prominent R wave is seen in lead I

Annular Ventricular Tachycardia VTs arising from the mitral or tricuspid annulusAccounts for 4% and 7% of cases of idiopathic VTMitral annular VT RBBB S wave in V6 monophasic R or Rs in leads V2 through V6

Mitral Annular VT

Tricuspid Annular VT foci generally arises from the septal region LBBB morphology in V1Early transition in precordial leads (V3)Relatively narrower QRS complexAnnular VTs behave similarly to outflow tract VT, both in prognosis and in drug response

Fasicular VT(Left Septal VT) Accounts for 7-12% of idiopathic VTAlso called as verapamil sensitive tachycardiaPresents in young adulthood with slight male preponderanceMechanism macroreentry using the left posterior (or less commonly anterior) fascicle and abnormal purkinje or adjacent ventricular myocardiumPrognosis is generally good

Left Posterior Fasicular VTRBBB morphology + Left axis deviation

Left Anterior Fasicular TachycardiaRBBB + Right Axis Deviation

Bidirectional VT ECGRBBB patternAxis alternating from 60 to 90 degrees to +120 to +130 degrees regular rhythmCauses Digitalis toxicity CPVT

Bidirectional VT

Torsades de PointesRefers to a VT characterized by QRS complexes of changing amplitude that appear to twist around the isoelectric line and occur at rates of 200 to 250/mincharacterized by prolonged ventricular repolarization with QT intervals generally exceeding 500 millisecondsVT that is similar morphologically to torsades de pointes and occurs in patients without QT prolongation, should generally be classified as polymorphic VT, not as torsades de pointes

Torsades de Pointes

Accelerated Idioventricular RhythmEnhanced ectopic ventricular rhythm with at least 3 consecutive ventricular beats, which is faster than normal intrinsic ventricular escape rhythm but slower than ventricular tachycardiaVentricular rate between 50 and 100 bpmCausesacute myocardial infarction shortly after successful reperfusiondigitalis toxicityDoes not affect prognosis in acute MINo treatment required

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Accelerated Idioventricular Rhythm

Ventricular FlutterSine wave pattern large regular oscillations without clear cut definitions of QRS complex and T waves ocurring at a rate of 150-300/minDifficult to distinguish between rapid VT & V.flutter

Ventricular fibrillationRecognized by the presence of irregular undulations of varying contour and amplitude occuring at a rate of 400-600/min Distinct QRS complexes, ST segments, and T waves are absent.

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