Cardiovascular Disorders Chapter 205. First-degree heart block is asymptomatic and may be physiologic. It is often seen in well-trained athletes, the young, and those with high vagal tone. The PR interval is prolonged in acute rheumatic fever and sarcoid heart disease and may have medicolegal implications for employment and insurance purposes. Even when first-degree heart block occurs in the setting of disease, treatment is not mandatory but may suggest further investigation.
Symptoms are rare.
Its importance relates to risk of progression to complete heart block. High-grade and Mobitz II blocks traditionally have been regarded as more serious than Wenckebach block. However, in patients with chronic cardiovascular disease, prophylactic permanent pacing should be considered for all second-degree heart block. In third-degree heart block, there is no electrical communication between the atria and the ventricles. Low pacemakers are slow, produce broad QRS complexes, and are unreliable.