An interference with the conduction of the electrical impulses of the heart. Blockage can be either partial or complete.
The slowing of the action of the heart because the impulses from the sinoatrial node to the ventricles are delayed or interrupted. There are either longer impulses (first degree block) or missing impulses (second degree block) or no impulses at all (complete heart block), in which case the ventricles continue to beat slowly and independently of the sinoatrial node.
Conduction disorder of the heart whereby electrical impulses are slowed either partially or completely; it may be a congenital condition or the result of a heart disorder, including those caused by medication or poisoning; symptoms may or may not occur, depending on the location of the block and the resultant heart rate.
A disorder of the electrical system that initiates and regulates the transmission of the heartbeat from the upper chamber of the heart (atrium) to the lower chamber (ventricle).
A slowing of electrical impulses in their normal conduction pattern from the atria (upper chambers) of the heart to the ventricles (lower chambers). The delay in electrical communication between the top and bottom of the heart can slow the heartbeat to an abnormally low rate (bradycardia).
A condition in which conduction of the electrical impulses generated by the natural pacemaker of the heart (the sinoatrial node) is impaired, so that the pumping action of the heart is slowed down. In partial or incomplete heart block conduction between atria and ventricles is delayed (first degree heart block) or not all the impulses are conducted from the atria to the ventricles {second degree heart block). In third degree or complete heart block no impulses are conducted and the ventricles beat at their own slow intrinsic rate (20-40 per minute).
Interference with the normal transmission of electrical impulses through the conducting system of the heart. The condition is seen on electrocardiogram as a prolongation of the P-R interval, a widening of the QRS complex, a delay in the appearance of an expected beat, the loss of synchrony of atrial and ventricular beats, or dropped (missing) beats.
A condition characterized by impaired electrical conduction in the heart muscle, which can result in an irregular heartbeat. Treatment for this condition may involve the use of a pacemaker.
Heart block is a prevalent condition affecting the rhythm of the heartbeat. It arises due to a disruption in the transmission of electrical impulses through the heart’s conduction system. Heart block may be present from birth or could result from heart conditions, such as coronary artery disease. Other potential causes include an overdose of a digitalis medication, which is used in heart disease treatment, and rheumatic fever.
There are two primary forms of heart block: atrioventricular block, where the obstruction occurs in the heart’s conducting system between an atrium (the upper chamber of the heart) and a ventricle (the lower chamber of the heart); and bundle branch block, in which the blockage is limited to conduction within the ventricles themselves.
Atrioventricular heart block comes in three distinct forms. The first degree block is characterized by an extended delay between the contraction of the atria and the ventricles. In the case of the second degree heart block, not all beats from the atria successfully reach the ventricles. The most severe form is the complete heart block, where the heart’s conducting system has a total blockage that obstructs beats from the atria from reaching the ventricles. As a result, the two chambers function at their individual natural rates, with the ventricles beating at a markedly slow pace, entirely independent from the atria.
Each ventricle possesses its distinct conduction system, referred to as the right and left bundle branches. These branches operate in tandem. If a blockage occurs in either of the bundle branches (or in rare cases, both), it results in an unusual conduction pattern throughout the ventricles.
Right bundle branch block can occasionally be observed in a healthy heart. However, it may also arise from certain conditions like congenital heart disease. On the other hand, the presence of a left bundle branch block is more concerning as it always indicates an underlying heart condition. The usual cause of this blockage is coronary artery disease, but it can also be triggered by high blood pressure or aortic stenosis.
First-degree heart block and an isolated left or right bundle branch block typically don’t cause any symptoms. However, in more severe cases of atrioventricular heart block, the contraction rate of the ventricles doesn’t accelerate during exercise. This might lead to shortness of breath due to heart failure (which means less efficient pumping), or chest pains related to angina pectoris (which is caused by reduced blood supply to the heart muscle). If the ventricular rhythm becomes extremely slow or completely halts for a few moments, it can result in episodes of fainting.
Both types of heart block can typically be identified through an ECG (electrocardiogram) scan. Heart block that does not present any symptoms might not need any treatment. However, if the heart block is causing symptoms, it is usually managed by implanting a permanent artificial pacemaker. Medications aimed at boosting the heart rate and enhancing the force of the heart’s contractions might be administered on a temporary basis. If any heart disease is found, it will be treated as required.
A disruption in the heart’s rhythm occurs when the atria beat more rapidly than the ventricles. This happens because of a break in the signal transmission between the atria and ventricles. Normally, heart contractions start in the atria and send impulses through a special bundle of nerves, known as the His bundle, located in the heart’s central wall. This ensures that the ventricles contract in coordination with the atria, creating a synchronized pattern from the atrium to the ventricle.