7) OX Ventricular tachyarrhythmias.

Question 1

etiology of ventricular tachycarythmia ?

Answer 1

cardiac scars- infraction or post operative

cardiomyopathies

drugs - digitalis

long QT syndrome - congenital or acquired
anti arrhythmia drugs class 1a quinidine ,
class 3 sotalol /amiodarone
fluroquinilones
haloperidol - antiphyscotics
electrolyte imbalance - hypokalaemia , hypomagneisa hypocalcemia

Question 2

what are the different types of ventricular tachyarrythmia ?

Answer 2

monomorphic VT - all qrs complexes look similar (re-entry circuits - myocardial scarring)

Polymorphic VT - dissimilar QRS complexes caused by abnormal ventricular repolarization

eg Torsades de pointes
Polymorphic ventricular tachycardia with QRS complexes that appear to twist around the isoelectric line
Cause: prolonged QT interval

Question 3

what are the clinical features of ventricular tachyarrythmia

Answer 3

Often asymptomatic, if nonsustained

symptoms of sustained VT:
Palpitations
Hypotension
Syncope
pulsless
chest pain

Question 4

complications ?

Answer 4

Progression to ventricular fibrillation

Sudden cardiac death

Question 5

ECG FINDINGS

Answer 5

3 or more consecutive premature ventricular beats = always widened QRS more than 0.12s

because of the high ventricular rate p waves and t waves are not visible

ventricles contract /Heart rate > 100 bpm

Duration
Nonsustained: < 30 s
Sustained: > 30 s

Morphology
Monomorphic: all QRS complexes look similar (identical origin)
Polymorphic: QRS complexes are different (multiple origins) - irregular irregular rhythm

AV-dissociation: no relationship between P waves and QRS complexes (in VT, ventricular rhythm is often faster than atrial rhythm)

Question 6

Other diagnostic tests?

Answer 6

Holter monitor: useful for diagnosing intermittent VT which may not be present on a single ECG

Patient-activated (manual) event recorder

Echocardiography: provides information about possible etiologies of VT (e.g. structural heart disease, prior MI) and is thus a useful tool for evaluation of VT

Question 7

what features favour VT to SVT as DD because its important how we treat the patient?

Answer 7

Absence of typical RBBB or LBBB morphology

there is extreme axis deviation - qrs is positive in AVR
negative in AVF and lead 1

very broad qrs complexes

AV dissociation -no relationship between p waves and qrs complex

fusion beats -atrial and ventricular impulses occur simultaneously

capture beats - usually after fusion complex. sinoatrial node transiently ‘captures’ the ventricles, in the midst of AV dissociation, to produce a QRS complex of normal duration

Question 8

difference between v tach and v fib?

Answer 8

Vfib is rapid totally incoordinate contraction of ventricular fibers; the EKG shows chaotic electrical activity and clinically the patient has no pulse

Question 9

therapy of VT of hemodynamially unstable patient ?

Answer 9

Adverse signs?
• Shock (BP <90mmHg, pulse >100)
• Chest pain/ischaemia on ECG
• Heart failure
• Syncope

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VT with pulse - syn electrical cardioverison

procedural sedation if patient is unconscious

paddles or electrode pads
place pads over mid sternum at base of the heart and the next pad on the mid axillary line
Choose the synchronized (SYNC) mode of shock on the defibrillator device.
Select the recommended dose of electrical energy according to the patient’s cardiac rhythm.
“Clear” the patient.
Deliver shock.
Reassess the rhythm and check the pulse

Up to 3 synchronized DC

Check and correct K+, Mg2+, Ca2+

 Amiodarone 300 mg IV over 10-20 min
 Repeat shock
 Then give amiodarone 900 mg over 24 hr

For refractory cases seek
expert help and consider:
• Procainamide
• Overdrive pacing

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VT without pulse - treated as VFIB

Question 10

what is the therapy of VT if it is hemodynamically stable ?

Answer 10

wide stable complex tacycardia
Includes monomorphic ventricular tachycardia, polymorphic ventricular tachycardia (e.g., torsades de pointes), supraventricular tachycardia with variable conduction

First-line treatment of VT: pharmacological cardioversion with antiarrhythmics
Patients with QT prolongation on baseline ECG: amiodarone
Patients without QT prolongation on baseline ECG: procainamide or sotalol
Refractory VT: electrical cardioversion

Cardioversion if medical therapy fails

In all patients, look for causes of VT such as:
Electrolyte abnormalities (e.g., hypokalemia)
and correct

Medication-induced QT prolongation → remove any offending medication

digoxin immune fab
digoxin specific antibody

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long term
use ICD - implanatable cardioverter defib