A Synopsis of AFPs "Management of Common Arrhythmias: Part II.Ventricular Arrhythmias and Arrhythmias in Special Populations"

A synopsis of: Management of Common Arrhythmias: Part II.Ventricular Arrhythmias and Arrhythmias in Special Populations
A. KESH HEBBAR, M.D., and WILLIAM J. HUESTON, M.D., Medical University of South Carolina, Charleston, South Carolina
Am Fam Physician. 2002 Jun 15;65(12):2491-2497
http://www.aafp.org/afp/2002/0615/p2491.pdf

     This is the second part of yesterday's article. PVCs are characterized by  wide a QRS complex (more than 0.12 secs, three small boxes), no preceding P wave, and a large T wave in the opposite direction of the QRS complex. It is usually followed by a "full compensatory pause".  Ventricular bigeminy is where the PVC alternates with a normal sinus contraction. In the absence of cardiac disease, there is no treatment needed for PVCs besides patient reassurance. If PVCs are causing severe,  uncomfortable symptoms, beta blockers are a safe first line choice, with flecainide, amiodarone and radiofrequency ablation as alternatives. In patients with heart disease, cardiomyopathy, and CHF, treating the underlying cause is paramount. PVCs are considered dangerous when there are 10 or more seen per hour, or when there are 3-5 consecutive contractions seen.
     VT is defined as three continuous PVCs.  The rate should be at least 100 BPM with a wide complex and no P waves. WPW or a bundle branch may mimic this ECG, and any wide complex tachycardia should be treated as a VT until it is ruled out. Management consists of amiodarone (or lidocaine) in asymptomatic, stable patients. Hemodynamically unstable patients should be treated with electrical cardioversion according to ACLs protocol.  Patients with life threatening VT may eventually need an implantable defibrillator in situations such as: VT or VF which has lead to cardiac arrest; spontaneous, sustained VT; sustained VT with syncope; VT with CAD and LV dysfunction.
     Pregnant women may have ectopic beats, it is usually benign. If there is a need for treatment, amiodarone and beta blockers should not be used during pregnancy. Amiodarone may cause fetal goiter, neonatal hypothyroidism, and fetal growth retardation. Beta blockers can cause IUGR and hypoglycemia.
     It is common for athletes to have slow heart rates, even with an occasional pause. Patients with a history or syncope with exercise, or family history of a close relative with sudden cardiac death at a young age, should be checked for idiopathic hypertrophic cardiomyopathy. These patients may have an aortic murmur that gets louder with valsalva.  Treatment includes a beta blocker or calcium channel blocker. They should also be instructed to avoid strenuous sports and exercise.
     The most common arrhythmia in children is SVT. The treatment is the same as with adults (adenosine). Patients may also have extra atrial or ventricular beats. These children will need further evaluation because it is associated with structural disease and a higher risk of death.
     Patients with acute MI can also develop rhythm abnormalities. Common abnormalities in this situation are sinus tachycardia, sinus bradycardia and PVCs.  Accelerated idioventricular rhythm is basically when the beat originates in the ventricle, and at a faster rate (60-125 BPM) than what the SA node would do. It is a benign form of VT that occurs during the reperfusion portion of an MI. Treatment is not needed. PVCs do not require treatment as well. VT does not need to be treated unless it occurs after 48 hours in patients with LV dysfunction. Sustained VT for more than 30 seconds will need treatment with the ACLS protocol.  Sinus bradycardia is common in inferior or posterior MI. Treatment can be done with atropine. If second degree type II or third degree heart block develops, pacing may be required.