(Complete heart block, in which no supraventricular impulses are conducted to the ventricles).
Heart block is an abnormal heart rhythm where the heart beats too slowly (bradycardia ). In this condition, the electrical signals that tell the heart to contract are partially or totally blocked between the upper chambers (atria) and the lower chambers (ventricles).
Complete (third-degree) heart block is a more advanced form of block often due to a lesion distal to the His bundle and associated with bilateral bundle branch block. The QRS is wide and the ventricular rate is slower, usually < 50 beats/min. Transmission of atrial impulses through the AV node is completely blocked, and a ventricular pacemaker maintains a slow, regular ventricular rate, usually < 45 beats/min.
Risk factors for Heart Block
Some medical conditions increase the risk for developing heart block. These medical conditions include:
• Heart failure
• Prior heart attack
• Heart valve abnormalities
• Heart valve surgery
• Congenital heart diseases
• Some medications or exposure to toxic substances
• Lyme disease