Peer Reviewed
ECG education
Is this second degree atrioventricular heart block?
Abstract
Helen is a 65-year-old woman who is well known to you. She comes to see you at your practice because she has been feeling faint when she does simple housework and especially if she exerts herself physically. This has been happening for a week but she has had no other symptoms. She has been taking perindopril plus indapamide daily for 10 years for hypertension. This medication was last increased to 5 mg/1.25 mg two years ago. She is clinically obese but has no other medical conditions.
Key Points
- Second degree atrioventricular heart block is either Mobitz type I (Wenckebach) where the PR interval becomes progressively prolonged over a number of heart beats until a P wave is not conducted, or Mobitz type II where the PR interval is fixed but there is a regular nonconduction of the P wave.
- Mobitz type I is more common, and Mobitz type II is more dangerous.
- Both Mobitz type I or II that involve the infranodal region may progress to complete heart block.
- The common causes of second degree heart block include use of medications, myocardial disease, electrolyte disorders, thyroid disease and aortic valvular disease.
- Patients with symptomatic heart block (dizziness, faintness, reduced exercise tolerance, angina with exertion and syncope) are likely to require a permanent pacemaker.
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