atrioventricular block - definition of atrioventricular block in the Medical dictionary - by the Free Online Medical Dictionary, Thesaurus and Encyclopedia.

block (blok)

2. to obstruct.

ankle block regional anesthesia of the foot by injection of anesthetic around the tibial nerves at the ankle.

atrioventricular block , AV block impairment of conduction of cardiac impulses from the atria to the ventricles, usually due to a block in the atrioventricular junctional tissue, and generally subclassified on the basis of severity as first, second, or third degree.

Bier block regional anesthesia by intravenous injection; used for surgical procedures on the arm below the elbow or leg below the knee that are done in a bloodless field maintained by a pneumatic tourniquet.

bifascicular block impairment of conduction in two of the three fascicles of the bundle branches.

bilateral bundle branch block (BBBB) interruption of cardiac impulses through both bundle branches, clinically indistinguishable from third degree (complete) heart block.

brachial plexus block regional anesthesia of the shoulder, arm, and hand by injection of anesthetic into the brachial plexus.

bundle branch block (BBB) interruption of conduction in one of the main bundle branches, so that the impulse first reaches one ventricle, then travels to the other.

caudal block anesthesia by injection of local anesthetic into the caudal or sacral canal.

cervical plexus block regional anesthesia of the neck by injection of a local anesthetic into the cervical plexus.

complete heart block see heart b.

conduction block a blockage in a nerve that prevents impulses from being conducted across a given segment although the nerve beyond is viable.

elbow block regional anesthesia of the forearm and hand by injection of local anesthetic around the median, radial, and ulnar nerves at the elbow.

entrance block in cardiology, a unidirectional impasse to conduction that prevents an impulse from entering a specific region of excitable tissue; part of the mechanism underlying parasystole.

epidural block regional anesthesia by injection into the epidural space, either between the vertebral spines, in the cervical, thoracic, or lumbar region, or into the sacral hiatus, which is also called caudal block

Production of epidural block by injection through the ligamentum flavum into the epidural space, the needle stopping just short of the dura mater.

exit block in cardiology, delay or failure of an impulse to be conducted from a specific region to surrounding tissues.

fascicular block any of a group of disorders of conduction localized within any combination of the three fascicles of the bundle branches or their ramifications.

femoral block regional anesthesia of the posterior thigh and the leg below the knee by injection of a local anesthetic around the femoral nerve just below the inguinal ligament at the lateral border of the fossa ovalis.

field block regional anesthesia by encircling the operative field with injections of a local anesthetic.

first degree heart block see heart b.; see also atrioventricular b.

heart block impairment of conduction of an impulse in heart excitation; it is subclassified as first degree when conduction time is prolonged, second degree (partial heart b.) when some atrial impulses are not conducted, and third degree (complete heart b.) when no atrial impulses are conducted; the term and its subcategories are often used specifically for atrioventricular block.

high grade atrioventricular block second or third degree atrioventricular block.

incomplete heart block first or second degree heart block.

intraspinal block spinal anesthesia (1).

intravenous block Bier b.

lumbar plexus block regional anesthesia of the anterior and medial aspects of the leg by injection of a local anesthetic into the lumbar plexus.

mental block blocking (2).

metabolic block the blocking of a biosynthetic pathway due to a genetic enzyme defect or to inhibition of an enzyme by a drug or other substance.

Mobitz type I block Wenckebach b.

Mobitz type II block a type of second degree atrioventricular block in which dropped beats occur periodically without previous lengthening of the P–R interval, due to a block within or below the bundle of His.

motor point block interruption of impulses, by anesthesia or destruction of the nerve, at a motor point in order to relieve spasticity.

nerve block regional anesthesia by injection of anesthetics close to the appropriate nerve.

paracervical block regional anesthesia of the inferior hypogastric plexus and ganglia produced by injection of the local anesthetic into the lateral fornices of the vagina.

parasacral block regional anesthesia produced by injection of a local anesthetic around the sacral nerves as they emerge from the sacral foramina.

paravertebral block infiltration of anesthetic into an area near the vertebrae.

partial heart block see heart b.

periinfarction block disturbance of intraventricular conduction after a myocardial infarction, due to delayed conduction in the infarct region.

presacral block anesthesia produced by injection of the local anesthetic into the sacral nerves on the anterior aspect of the sacrum.

pudendal block anesthesia produced by blocking the pudendal nerves, accomplished by injection of the local anesthetic into the tuberosity of the ischium.

retrobulbar block that performed by injection of a local anesthetic into the retrobulbar space to anesthetize and immobilize the eye.

sacral block see under anesthesia.

saddle block regional anesthesia in an area of the buttocks, perineum, and inner aspects of the thighs, by introducing the anesthetic agent low in the dural sac.

second degree heart block see heart b.; see also atrioventricular b.

sinoatrial block delay or absence of the atrial beat due to partial or complete interference with the propagation of impulses from the sinoatrial node to the atria.

spinal block see under anesthesia.

subarachnoid block spinal anesthesia (1).

third degree heart block see heart b.; see also atrioventricular b.

trifascicular block impairment of conduction in all three fascicles of the bundle branches, a form of complete heart block.

unifascicular block impairment of conduction in only one fascicle of the bundle branches.

vagal block , vagus nerve block blocking of vagal impulses by injection of a solution of local anesthetic into the vagus nerve at its exit from the skull.

Wenckebach block a type of second degree atrioventricular block in which one or more dropped beats occur periodically after a series of steadily increasing P–R intervals.

wrist block regional anesthesia of the hand by injection of a local anesthetic around the median, radial, and ulnar nerves of the wrist.

atrioventricular block

Impairment of the normal conduction of impulses between the atria and the ventricles.

atrioventricular block (AVB)

Etymology: L, atrium + ventriculus, little belly

a disorder of cardiac impulse transmission that reflects prolonged, intermittent, or absent conduction of impulses between the atria and ventricles. It commonly occurs at the AV node or within the bundle branch system. Treatment depends on where the block is located and whether it is transient or permanent. Heart rate-supporting drugs or pacemaker insertion are common options. See also heart block, intraatrial block, intraventricular block, sinoatrial (SA) block.

atrioventricular

pertaining to an atrium and ventricle of the heart.

accessory tract atrioventricular conduction

see accessory tract atrioventricular conduction.

atrioventricular block

see atrioventricular heart block.

atrioventricular bundle

bundle of His.

common atrioventricular canal

a congenital cardiac defect in which both sides of the heart share the same atrioventricular orifice. Called also persistent atrioventricular canal, atrioventricularis communis.

atrioventricular node

a mass of cardiac muscle fibers (Purkinje fibers) lying on the right lower part of the interatrial septum of the heart. Its function is the transmission of the cardiac impulse from the sinoatrial node to the muscular walls of the ventricles. The conductive system is organized so that transmission is slightly delayed at the atrioventricular node, thus allowing time for the atria to empty their contents into the ventricles before the ventricles begin to contract.

partitioning atrioventricular canal

during embryological development partitioning of the cardiac chambers and their orifices may be incomplete, leading to fatal cardiac defects, e.g. persistent atrioventricular chamber.

persistent common atrioventricular canal

see atrioventricularis communis.

atrioventricular stenosis

left and right atrioventricular stenosis are recorded; the former is an acyanotic defect, the latter is more serious and a cyanotic defect.

atrioventricular trunk

see bundle of His.

atrioventricular valvular disease

may be identifiable on finding of systolic murmur (incompetent valve) or diastolic murmur (stenotic valve) over the apex of the heart with maximum audibility over the left or right sides, depending on the side involved.

Wenckebach atrioventricular block

see Mobitz atrioventricular heart block.

atrioventricular block

A-V block Cardiology A delay in conduction or failure of the electrical impulse to reach the ventricular conducting system, which may occur at the atrium, at the A-V node, in the bundle of His, or in the bundle branches Drugs causing Clonidine, methyldopa, verapamil Clinical Asymptomatic or may require a pacemaker. See Complete heart block, Sick sinus syndrome

Atrioventricular Blocks

1^st -degree A-V block

P-R intervals > 0.2 sec; all P waves are conducted to ventricle, ie, followed by a QRS complex–usually benign

2^nd -degree A-V block

Mobitz I–aka Wenckebach block: P-R intervals ↑ in length until a beat is 'dropped'; PR interval after a blocked beat is prolonged; Mobitz I blocks often follow an MI–usually benign
Mobitz II: P-R interval of conducted beat is constant–conduction ratio ≥ 3:1; occasionally P fails to conduct an impulse–may have serious clinical implications

3^rd -degree A-V block

Dissociation of atrial and ventricular activity; atrial rate is > ventricular rate; permanent pacemaker is required