Ventricular Tachycardia

Dr. Akshay Chincholi

Ventricular Tachycardia

• Arrhythmia of three or more consecutive complexes in duration originating from the ventricles at a rate of ≥100 bpm

• Accounts for up to 80% of Wide complex tachycardia• Nonsustained VT

– Three or more beats in duration, terminating spontaneously in less than 30 s.

• Sustained VT– VT greater than 30 s in duration and/or requiring termination

due to hemodynamic compromise in less than 30 s.

• Rate 100 to 250 / min• Rhythm- Regular / slightly irregular • QRS duration– RBBB >140ms– LBBB >160ms

• QRS 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 V6

– occurs in only 15% of VTs with specificity of >90%– positive concordance seen in 18% of VTs with

RBBB-type pattern– 12% 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 Complexes• A capture complex occurs when a supraventricular

impulse propagates through the normal HPS system between VT QRS complexes and excites both ventricles completely

• Capture complexes are narrow QRS complexes similar to sinus complexes

• Fused QRS complexes are those in which the QRS is a combination of 2 sources of ventricular activation (supraventricular and ventricular during VT)

QRS mprphology• In Precordial leads

– Concordant– No R/S pattern– Onset of R to nadir longer than 100 msec

• RBBB pattern– qR, Rs or Rr´ in V1

– broad R (>40 ms) in lead V1– rS complex in lead V6

• LBBB pattern– r in V1 longer than 30 msec– R to nadir of S in V1 greater than 60 msec– Notching in the downstroke of the S wave– qR or qS in V6

• Other specific patterns in V1– Rs and W configuration in V1

• :

No RS Pattern

KINDWALL CRITERIA

KINDWALL CRITERIA

MILLER CRITERIA

Idiopathic Ventricular Tachycardia

• Refers 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 VT– Outflow tract tachycardia– Annular VT– Fascicular VT (left septal VT)

Outflow Tract Tachycardia

• Accounts for 50% of idiopathic VT and 10% of all VTs

• Types – RVOT VT (80%)– LVOT VT (20%)

• Occurs in young to middle age patients • Mechanism – cAMP mediated delayed

afterdepolarizations

• RVOT VT– LBBB pattern + Inferior axis – R wave transition at or later than V3

• LVOT VT – 2 patterns on ECG– RBBB 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 VT• exercise, 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 annulus• Accounts for 4% and 7% of cases of idiopathic

VT• Mitral 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 V1– Early transition in precordial leads (V3)– Relatively narrower QRS complex

• Annular 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 VT• Also called as verapamil sensitive tachycardia• Presents in young adulthood with slight male

preponderance• Mechanism – macroreentry using the left

posterior (or less commonly anterior) fascicle and abnormal purkinje or adjacent ventricular myocardium

• Prognosis is generally good

Left Posterior Fasicular VTRBBB morphology + Left axis deviation

Left Anterior Fasicular TachycardiaRBBB + Right Axis Deviation

Bidirectional VT

• ECG– RBBB pattern– Axis alternating from −60 to −90 degrees to +120

to +130 degrees – regular rhythm

• Causes – Digitalis toxicity – CPVT

Bidirectional VT

Torsades de Pointes

• Refers 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/min

• characterized by prolonged ventricular repolarization with QT intervals generally exceeding 500 milliseconds

• VT 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 Rhythm

• Enhanced ectopic ventricular rhythm with at least 3 consecutive ventricular beats, which is faster than normal intrinsic ventricular escape rhythm but slower than ventricular tachycardia

• Ventricular rate between 50 and 100 bpm• Causes– acute myocardial infarction shortly after successful reperfusion– digitalis toxicity

• Does not affect prognosis in acute MI• No treatment required

Accelerated Idioventricular Rhythm

Ventricular Flutter

• Sine wave pattern – large regular oscillations without clear cut definitions of QRS complex and T waves ocurring at a rate of 150-300/min

• Difficult to distinguish between rapid VT & V.flutter

Ventricular fibrillation

• Recognized 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.