Etiology

  CPVT1 (Type 1): Most frequent. Autosomal dominant.

      Due to mutations of the
RYR2 gene which encodes the cardiac ryanodine receptor.

 
CPVT2 (Type 2): Less frequent. Autosomal recessive.

      Due to mutations of the
CASQ2 gene which encodes the calsequestrin.

  Both genes are involved in
intracellular calcium release and cellular contraction.



Diagnostic criteria

  Observation of bidirectional VT or polymorphic VT during exercise test is diagnostic.

  Although observation of bidirectional VT during exercise stress test is typical for the diagnosis of CPVT,

      this arrhythmia can be observed only in one thirds of the CPVT patients.

  If typical bidirectional VT is not observed during exercise test, then another finding may also suggest

      the diagnosis of CPVT: the arrhythmias observed during exercise test progressively worsen as

      exercise goes on.

  Ventricular arrhythmias (frequent VPCs) usually appear at heart rates between 110-120 beats/minute.

      As the patient continues to exercise ventricular bigeminy, ventricular couplet, bidirectional VT or

      polymorphic VT usually appear. As the patient stops exercising, these arrhythmias also disappear gradually.

  Generally the resting ECG is expected to be normal.

  The QT interval of the resting ECG is also expected to be normal.

  Recently, sinus bradycardia, prominent U waves and short PR interval are reported to occur

      more frequently in CPVT patients.

  Echocardiography shows no structural heart disease.




Clinical significance

  Physical stress (exercise) or intense emotional stress may result in syncope or sudden death.

  CPVT patients are advised not to exercise heavily.

 
Beta blockers are reported to be only partially effective in CPVT patients.

  May be observed both in children and adults.

      The mean age at which clinical symptoms appear is
7-9 years of age.

  Some CPVT patients may be erroneously diagnosed as having epilepsy.

  CPVT has a
high mortality rate. About 30-35% of the patients may not live longer than 30 years.



Differential diagnosis

  It has been reported that, about 30% of the CPVT patients are erroneously diagnosed to have LQTS

      with a normal QT interval (concealed LQTS). Both diseases may result in exertional syncope.

  In CPVT, the arrhythmias may be easily induced by exercise, isopreterenol infusion

      or other types of adrenergic stimulus.

  Bidirectional VT showing 180 degrees change of axis
on a beat-to-beat basis is enough to diagnose CPVT.



Other than CPVT, bidirectional VT may also be observed in

  Digoxin intoxication

  Andersen-Tawil Syndrome (ATS)




References

  JACC 2009; 54: 2065-2074.

  Progress in Cardiovascular Diseases 2008; 51: 23-30.

  Int Heart J 2006; 47: 381-389.

  Can J Cardiol 2007; 23, Suppl A: 16A-22A.

  Heart 2003; 89: 66-70.

  J Med Genet 2005; 42: 863-870.

  Curr Probl Cardiol 2009; 34: 9-43.





ECG 1. Bidirectional ventricular tachycardia (VT) in a patient with CPVT.

The ECG above, has been donated by Prof. Dr. Silvia Priori.

Click here for a more detailed ECG





ECG 2. Polymorphic ventricular tachycardia (VT) is seen in the ECG of a 15 years old patient with CPVT. The patient
experienced his first syncope 3 years ago. Although he has been receiving 20 mg of bisoprolol per day, his VT attacks
have not been controlled completely.

The ECG above, has been donated by Dr. Eyal Nof.





ECG 3. Prominent U waves in the resting ECG of a patient with CPVT.

The ECG above, has been donated by Dr. Peter Kukla.

Click here for a more detailed ECG





ECG 4. Prominent U waves in the resting ECG of a patient with CPVT.

The ECG above, has been donated by Dr. Peter Kukla.

Click here for a more detailed ECG





ECG 5. Bidirectional ventricular tachycardia (VT) in a patient with CPVT.

The ECG above, has been donated by Dr. Peter Kukla.

Click here for a more detailed ECG





ECG 6. Polymorphic ventricular tachycardia (VT) in a patient diagnosed as CPVT.

The ECG above, has been donated by Dr. Peter Kukla.

Click here for a more detailed ECG





ECG 7. Polymorphic ventricular tachycardia in another patient with CPVT.

The ECG above, has been donated by Dr. Peter Kukla.

Click here for a more detailed ECG





ECG 8. CPVT.

The ECG above, has been donated by Dr. Peter Kukla.

Click here for a more detailed ECG





ECG 9. Polymorphic ventricular premature contractions (VPCs) which arise after stimulation with adrenalin in a patient with
CPVT.

The ECG above, has been donated by Dr. Peter Kukla.

Click here for a more detailed ECG





ECG 10. The ECG above shows bidirectional ventricular tachycardia that arose at peak exercise in a patient with CPVT.

Dr. Andrew Krahn has donated this ECG to our website.

Click here for a more detailed ECG