section name header

Info


A. Atrial Premature Beats (APB) [1]

  1. ECG Changes
    1. Premature abnormal P wave (P'); Previous T wave may deform
    2. Usually conducted to ventricles, leads to normal, premature QRS
    3. Can give bundle branch block pattern; leads to ventricular aberration
    4. If T wave deformed, may not see P waves (falls on T)
    5. Differential includes wandering atrial pacemaker
  2. Setting
    1. Premature Atrial Contractions (PAC, APB) with 2:1 block very common in COPD
    2. Digitalis toxicity
  3. Treatment
    1. Not usually treated unless precipitates atrial fibrillation, supraventircular tachycardia
    2. Type I anti-arrhythmics are often used: quinidine, procainamide
    3. With fast AV conduction, use drug slowing Ventricular response, eg. verapamil

B. Ventricular Premature Beats (VPBs, PVCs)

  1. Etiology
    1. Ectopic beats arising in ventricles; occur before correct ventricular firing
    2. VPB lands on T wave can cause ventricular tachycardia or fibrillation
  2. ECG Changes
    1. Usually land on "U" wave; usually fixed distance from ectopic to next beat
    2. Wide, bizarre QRS characteristic of ventricular focus
    3. Initial deflection usu opposite to main deflection
    4. Usually followed by compensatory pause
    5. T wave following VPB QRS is inverted with respect to the QRS direction.
    6. When sandwiched between two consecutive beats, the beat is called "interpolated"
  3. Alternating VPB and sinus beats
    1. VPB and one sinus beat (1:1) is called ventricular bigemini
    2. 2 VPB's and one sinus beat (2:1) is called ventricular trigemini
  4. Holter monitoring is usually used for detection
  5. However, cardiac event recorders are more sensitive in patients with palpitations [2,3]
  6. Frequency and nature of PVCs can correlate with increased mortality in coronary artery disease patients
  7. Frequency of PVCs increases with age
  8. PVCs more common in men than women

References

  1. Zimetbaum P and Josephson ME. 1998. NEJM. 338(19):1369 abstract
  2. Kinlay S, Leitch JW, Neil A, et al. 1996. Ann Intern Med. 124(1):16 abstract
  3. Zimetbaum PJ, Kim K, Josephson ME, Goldberger A. 1998. Ann Intern Med. 128(11):890 abstract