Atrioventricular block revisited

Abstract

AV blocks, their definitions and significance, are discussed. Type II, second-degree AV block is infranodal, whereas 2/3 of Type I with BBB are infranodal, 2:1 AV block is neither Type I nor II block. Infranodal blocks require pacing regardless of symptoms.

Long‐term Intrinsic Rhythm Evaluation in Dogs with Atrioventricular Block

“…The majority of dogs reported here presented with similar changes in AV conduction disturbances over time as have been described in human patients, where 83% of the cases affected by AVB and treated with permanent PMI show persistent and progressive AVB at long‐term follow‐up . Progressive idiopathic fibrosis of the conduction system related to aging of the cardiac skeleton (Lev's disease) is the most common cause of chronic acquired AVB in humans . Presumably, most of our cases of unchanged or progressive AVB suffered from chronic fibrous or fibrous‐fatty replacement of the AV bundle and branches, as previously reported in the veterinary literature .…”

“…[25][26][27] Progressive idiopathic fibrosis of the conduction system related to aging of the cardiac skeleton (Lev's disease) is the most common cause of chronic acquired AVB in humans. 7,8 Presumably, most of our cases of unchanged or progressive AVB suffered from chronic fibrous or fibrous-fatty replacement of the AV bundle and branches, as previously reported in the veterinary literature. 3 In our study, paroxysmal 3AVB progressed to permanent 3AVB in the majority of the dogs, and in all cases of 3AVB with AF improvement in AV conduction disturbances was not documented.…”

“…Chronic and progressive AVB has been reported in older dogs and is thought to be caused by AV bundle degeneration, atrophy, and loss of conduction fibers secondary to compression and distortion of the central fibrous body . This condition is similar to Lev's disease in humans, in which degeneration of the AV conduction system leads to progressive and persistent AVB . Conversely, a transient form of AVB, characterized by an acute onset and high resolution rate, has been reported in children affected by acute lymphocytic myocarditis .…”

“…3 This condition is similar to Lev's disease in humans, in which degeneration of the AV conduction system leads to progressive and persistent AVB. 7 Conversely, a transient form of AVB, characterized by an acute onset and high resolution rate, has been reported in children affected by acute lymphocytic myocarditis. [8][9][10] This type of AVB also has been described in young dogs, [4][5][6] and is characterized by severe lymphocytic-plasmacytic myocarditis and mild fibrous-fatty replacement involving the AV node.…”