3 minutes crash course on ventricular ectopic beats (VPDs)
Posted Jul 09 2009 4:45pm
Ventricular ectopic beats are the most common cardiac electrical abnormality for which cardiologist’s consultation is sought.VPDs are one of most benign observations in ECG and and almost every heart experiences it. In 24 hour holter recordings it was reported up to 25% of healthy individuals .
In spite of this , the fear of noting a VPD in a given tracing of ECG is genuine both for the patient and his physician.This is because VPDs can be a forerunner of dangerous ventricular arrhythmias.
VPDs are often graded according to the count and morphology and frequency.(Lown’s ,Bigger’s grading)
VPDs that occur in single are less fearsome.( It may not be so . . .)
VPDs in couplets and triplets raise considerable anxiety.( Again it need not be . . .)
A series of VPD lasting for 30 seconds is called non sustained ventricular tachycardia(NSVT)
If it exceeds 30second it called sustained VT.
VT may remain as VT in many.
VT may degenerate into VF ventricular fibrillation in minority( ie cardiac arrest)
The importance of VPDs do not lie in the number , morphology or frequency but most importantly in the underlying etiology. If it occurs in a structurally normal heart it is largely benign.
New onset VPDs should be investigated thoroughly. The commonest symptom is palpitation.
Friendly VPD s : Some of situations where VPDs are commonly observed and has little significance are.
Exercise induced VPDs
Pregnancy induced VPDs (PIH /Peripartum DCM are rare possibilities)
Thyroid associated VPDs
Alcohol /Smoke related
What are the VPDs that could be clinically important ?
VPDs with chest pain(Ischemic etiology )
VPDs in patients with dyspnea.(CHF , COPD)
Drug induced VPDs(Digoxin etc)
Renal failure associated VPDs
VPDs due to hypoxia/Hypokalemia
In patients with pre existing heart disease.(Congenital, valvular, myocardial disease)
What prevents a non sustained VT from becoming sustained ?
No one really knows the answer.Most of the NSVT self terminates.A healthy heart some how gets the capacity to self terminate the arrhythmia.The normal LV fails to sustain the abnormal electrical circuit . A diseased heart may not be able to do so . Further if there is electrolyte abnormality (low potassium), or lack of oxygen it may maintain a VT.
What are the most dangerous forms of VPDs ?
VPDs that occur during acute coronary syndrome.
VPDs associated with cardiomyopathy( Ischemic , nonischmic,)
Some forms of primary electrical disorders of heart( Brugada syndrome, ARVD , CMVT etc)
How do you investigate patients with VPDs?
General medical work up in all.
Echocardiogram is usually necessary in most.
Holter monitoring in occasionally.
Coroanry angiogram rarely
Electrophysiological study in high risk category
How do you manage patients with VPDs?
Generally do not require any specific drugs in vast majority of individuals .
Reassurance is the key
Ask them to avoid potential triggers like smoke, alcohol, coffee, tea and related bevarages.
If palpitation is troublesome beta blockers( Propronolol, Atenolol, metoprolol can be used.)
Anxiolytic may also be given.
* If the patient has systemic disorder like hyperthyroidsm , anemia or underlying heart disease he has to get the specific treatment.
Caution:It has become fashionable for the physicians to use powerful antiarrhythmic drugs like amiodarone (Cordarone) liberally in patients with asymptomatic VPDs with structurally normal hearts.this practice must be absolutely avoided as amiodarone is one of most toxic cardiac drugs known with great pro arrhythmic activity.
When to refer a patient with VPD to a electrophysiologist ?
Physicians can treat most of these patients. But the following will require EP consultations
Patients with syncope
Patient who have LV dysfunction(Low ejection fraction EF%)
Has had an episode of ventricular tachycardia
What will the Electrophysiologist do ?
These patients will be evaluated for inducibility of VT/VF and if the LV function is poor (EF<30% MADIT 2 criteria ) many would receive implantable cardivertor defibrillator(ICD) or life long anti arrhythmic drugs.
Some times radiofrequency (RF ablation) waves are used to ablate the focus of VT.This is possible only if it occurs close to endocardium as intracardiac catheters do not have access to epicardial focus. Among ICD and RF ablation later could be preferred whenever feasible as it eliminates the arrhythmia , while the former only tackles it only after it occurs .( Hence ICDs , even though a technological marvel can not be labelled as curative ! )
VPDs are the most common cardiac arrhythmia .Most of them are benign. Few of them require extensive investigation.