Third degree AV block causes

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Cafer Zorkun, M.D., Ph.D. [2]; Raviteja Guddeti, M.B.B.S. [3]; Hilda Mahmoudi M.D., M.P.H.[4]

Overview

Many conditions can cause third degree AV block, but the most common cause is coronary ischemia. Progressive degeneration of the electrical conduction system of the heart can lead to complete heart block. In addition, acute myocardial infarction may present with third degree AV block.
Third degree heart block may also be congenital and has been linked to the presence of lupus in the mother. The cause of congenital third degree heart block in many patients is unknown.

Causes

Infiltration, fibrosis, or loss of connection in the heart conduction system can tend to heart block. A complete heart block can be either congenital or acquired.

Congenital form of complete heart block

  • Usually occurs at AVN.
  • Patients are relatively asymptomatic at rest.
  • Since the fixed heart rate is not able to adjust for exertion the become symptomatic with activity.
  • It may happen in the context of major structural abnormalities:  patients with L-transposition of the great arteries and two normally sized ventricles, as well as those with L-looped single-ventricle L-transposition of the great arteries, are at risk for spontaneous complete heart block and should undergo routine screening for complete heart block.
  • Or might be associated with maternal antibodies to SS-A (Ro) and SS-B (La).

Common causes of acquired AV block are as follows:

  • Ischemia or infarction:
  • AV node (AVN) block associated with inferior wall myocardial infarction (MI)
  • His-Purkinje block associated with anterior wall MI
  • Drugs:
  • Class Ia antiarrhythmics: quinidine, procainamide, disopyramide
  • Class Ic antiarrhythmics: eg, flecainide, encainide, propafenone
  • Class II antiarrhythmics: beta-blockers
  • Class III antiarrhythmics: eg, amiodarone, sotalol, dofetilide, ibutilide
  • Class IV antiarrhythmics: calcium channel blockers
  • Digoxin and other cardiac glycosides
  • Infectious disease:
  • Lyme borreliosis (particularly in endemic areas),
  • Myocarditis
  • Aspergillus myocarditis
  • Chagas disease: Trypanosoma cruzi infection
  • Varicella-zoster virus infection
  • Valve ring abscess
  • Degenerative diseases:
  • Lenègre disease (sclerodegenerative process involving only the conduction system)
  • Lev disease (calcification of the conduction system and valves)
  • Noncompaction cardiomyopathy
  • Nail-patella syndrome
  • Mitochondrial myopathy
  • Rheumatic diseases:
  • Ankylosing spondylitis
  • Reiter syndrome
  • Relapsing polychondritis
  • Rheumatoid arthritis
  • Rheumatic fever
  • Scleroderma
  • Infiltrative pathologies:
  • Amyloidosis
  • Sarcoidosis
  • Malignan or benign tumors
  • Hodgkin lymphoma
  • Multiple myeloma
  • Neuromuscular disorders:
  • Becker muscular dystrophy
  • Myotonic dystrophy
  • Metabolic abnormality:
  • Hypoxia
  • Hyperkalemia
  • Hypothyroidism
  • Toxins:
  • Grayanotoxin:“Mad” honey
  • Natural cardiac glycosides such as oleandrin
  • Bradycardia-related block
  • Iatrogenic heart block


Myocardial infarction

Anterior wall MI can be associated with an infranodal complete AV block; this is an ominous finding. Complete heart block develops in slightly less than 10% of cases of acute inferior MI and is much less dangerous, often resolving within hours to a few days.

Studies suggest that AV block rarely complicates MI. [9, 10] With an early revascularization strategy, the incidence of AV block decreased from 5.3% to 3.7%. Occlusion of each of the coronary arteries can result in development of conduction disease despite a redundant vascular supply to the AVN from all coronary arteries.

In a study that evaluated complete AV block in 4,799 Portugese patients with acute coronary syndrome (ACS), investigators noted 1.9% (n = 91) had complete AV block, of whom 86.8% had ST-segment elevation MI (STEMI), including 79.1% with confirmed inferior STEMI. [11]  Compared to the patients with ACS without AV block, those with complete AV block had right ventricular MI more often, as well as worse outcomes during hospitalization (higher incidence of cardiogenic shock, ventricular arrhythmias, need for invasive mechanical ventilation, death). [11]

Most commonly, occlusion of the right coronary artery (RCA) is accompanied by AV block. In particular, the proximal RCA occlusion has a high incidence of AV block (24%) because there is involvement not only of the AV nodal artery but also of the right superior descending artery, which originates from the very proximal part of the RCA.

In most cases, AV block resolves promptly after revascularization, but sometimes the course is prolonged. Overall, the prognosis is favorable. However, AV block in the setting of occlusion of the left anterior descending artery (particularly proximal to the first septal perforator) has a more ominous prognosis and usually calls for pacemaker implantation. Second-degree AV block associated with bundle-branch block and in particular with alternating bundle-branch block is an indication for permanent pacing.

Iatrogenic etiologies

AV block may be associated with aortic valve surgery, septal alcohol ablation, percutaneous coronary intervention (PCI) to the left anterior descending artery, or ablation of the slow or fast pathway of the AVN. Placement of catheters that mechanically interfere with one fascicle when conduction is already impaired in the remaining conduction system (eg, bumping the right bundle with a pulmonary artery catheter in a patient with existing left bundle-branch block) almost always resolves spontaneously.

AV block after cardiac surgery is seen in 1%-5.7% of patients. [12]  The incidence of postoperative complete heart block has remained relatively stable over the past decade, but it is highly associated with surgeries involving repair of a ventricular septal defect. [13]  Patients may have late loss or late recovery of AV conduction. [13]

Major risks factors identified for the need for permanent pacing are aortic valve surgery, [14] preexisting conduction disease (either right or left bundle-branch block), bicuspid aortic valve, annular calcification, and female sex. The time course for recovery varies widely, with a significant portion of patients recovering during the 48 hours following surgery. Available evidence suggests that if no recovery in AV conduction is seen by postoperative day 4 or 5, a pacemaker should be implanted.

Data from the Harmonizing Outcomes with Revascularization and Stents in Acute Myocardial Infarction (HORIZONS-AMI) Trial, in which 3,115 patients with STEMI underwent PCI, revealed that independent predictors of high-grade AV block included increased age, diabetes mellitus, right coronary artery occlusion, sum of ST-segment deviation, and baseline Thrombolysis In Myocardial Infarction (TIMI) flow 0/1. [15] Mortality was also significantly higher in those with high-grade AV block at 1 year but not at 30 days or 3 years, even after primary PCI.



Life Threatening Causes

Third degree heart block is a life-threatening condition and must be treated as such irrespective of the causes. Life-threatening conditions can result in death or permanent disability within 24 hours if left untreated.

Common Causes

Causes by Organ System

Cardiovascular Acute rheumatic fever, amyloidosis, aspergillosis myocarditis, atrial septal defect, bacterial endocarditis, congenital heart block,[2] coronary ischemia, dilated cardiomyopathy, Ebstein's anomaly, endocardial cushion defect, hypertension,[3] hypertrophic cardiomyopathy, hypertrophic cardiomyopathy alcohol septal ablation,[4] idiopathic heart block,[5][2] idiopathic hypereosinophilic syndrome, mitochondrial myopathy, myocardial infarction,[1] myocarditis, noncompaction cardiomyopathy, tetralogy of fallot, transposition of the great vessels, valvular heart disease, ventricular septal defect
Chemical/Poisoning No underlying causes
Dental No underlying causes
Dermatologic No underlying causes
Drug Side Effect Arsenic trioxide, Beta-blocker, calcium channel blocker,[6] cardiac glycosides, cholinesterase inhibitor, digitalis, procainamide, quinidine
Ear Nose Throat No underlying causes
Endocrine Amyloidosis, hyperthyroidism,[7]
Environmental No underlying causes
Gastroenterologic No underlying causes
Genetic Erb's dystrophy, Kearns-Sayre syndrome, nail-patella syndrome
Hematologic Thalassemia major[8]
Iatrogenic Cardiac surgery
Infectious Disease Aspergillosis myocarditis, bacterial endocarditis, Chagas disease, diphtheria,

lyme disease,[9][10][11] varicella zoster

Musculoskeletal/Orthopedic No underlying causes
Neurologic Enhanced vagal tone, idiopathic hypereosinophilic syndrome
Nutritional/Metabolic Amyloidosis, hemochromatosis
Obstetric/Gynecologic No underlying causes
Oncologic Hodgkin disease, multiple myeloma, tumor[12][13]
Ophthalmologic No underlying causes
Overdose/Toxicity Alcohol intoxication[14][15]
Psychiatric No underlying causes
Pulmonary No underlying causes
Renal/Electrolyte Hyperkalemia
Rheumatology/Immunology/Allergy Amyloidosis, ankylosing spondylitis, Becker muscular dystrophy, Churg-Strauss syndrome,[16] degenerative diseases, dermatomyositis, Erb's dystrophy, idiopathic hypereosinophilic syndrome, muscular dystrophy[17] myotonic muscular dystrophy, peroneal muscular atrophy, Reiter's syndrome, relapsing polychondritis,sarcoidosis, scleroderma,[18] neonatal lupus erythematosus
Sexual No underlying causes
Trauma No underlying causes
Urologic No underlying causes
Miscellaneous Trauma[19][20]

Third degree AV block causes developed by WikiDoc.org

Causes in Alphabetical Order

References

  1. ↑ 1.0 1.1 1.2 Malla RR, Sayami A (2007). "In hospital complications and mortality of patients of inferior wall myocardial infarction with right ventricular infarction". JNMA J Nepal Med Assoc. 46 (167): 99–102. PMID 18274563.
  2. ↑ 2.0 2.1 2.2 2.3 "Congenital complete atrioventricular". Retrieved 21 August 2013. Text "block. " ignored (help)
  3. ↑ 3.0 3.1 Lionakis N, Moyssakis I, Gialafos E, Dalianis N, Votteas V (2008). "Aortic dissection and third-degree atrioventricular block in a patient with a hypertensive crisis". J Clin Hypertens (Greenwich). 10 (1): 69–72. PMID 18174773. Unknown parameter |month= ignored (help)
  4. ↑ 4.0 4.1 Liu R, Qiao SB, Hu FH, Yang WX, Yuan JS (2012). "[Clinical features of five patients with delayed third degree atrioventricular block after ethanol septal ablation for hypertrophic obstructive cardiomyopathy]". Zhonghua Xin Xue Guan Bing Za Zhi (in Chinese). 40 (12): 1009–11. PMID 23363714. Unknown parameter |month= ignored (help)
  5. ↑ 5.0 5.1 Sykes JA, Lubega J, Ezetendu C, Verma R, O'Connor B, Kalyanaraman M (2011). "Asymptomatic complete atrioventricular block in a 13-year-old girl". Pediatr Emerg Care. 27 (11): 1081–3. doi:10.1097/PEC.0b013e3182360674. PMID 22068075. Unknown parameter |month= ignored (help)
  6. ↑ 6.0 6.1 Wills BK, Liu JM, Wahl M (2010). "Third-degree AV block [from extended-release diltiazem ingestion in a nine-month-old". J Emerg Med. 38 (3): 328–31. doi:10.1016/j.jemermed.2007.10.053. PMID 18403171. Unknown parameter |month= ignored (help)
  7. ↑ 7.0 7.1 Amasyalı B, Barçın C, Kılıç A (2011). "[Supra-His complete atrioventricular block in a patient with subclinical hyperthyroidism]". Turk Kardiyol Dern Ars (in Turkish). 39 (8): 693–6. PMID 22257810. Unknown parameter |month= ignored (help)
  8. ↑ 8.0 8.1 Maleki AR, Nikyar B, Hosseini SM (2012). "Third-Degree Heart Block in Thalassemia major: A Case Report". Iran J Pediatr. 22 (2): 260–4. PMC 3446065. PMID 23056897. Unknown parameter |month= ignored (help)
  9. ↑ 9.0 9.1 Bhattacharya IS, Dweck M, Francis M (2010). "Lyme carditis: a". J R Coll Physicians Edinb. 40 (2): 121–2. doi:10.4997/JRCPE.2010.207. PMID 21125053. Text "reversible cause of complete atrioventricular block " ignored (help); Unknown parameter |month= ignored (help)
  10. ↑ 10.0 10.1 Wagner V, Zima E, Gellér L, Merkely B (2010). "[Acute atrioventricular block in chronic Lyme disease]". Orv Hetil (in Hungarian). 151 (39): 1585–90. doi:10.1556/OH.2010.28965. PMID 20840915. Unknown parameter |month= ignored (help)
  11. ↑ 11.0 11.1 Semmler D, Blank R, Rupprecht H (2010). "Complete AV block in Lyme carditis: an important differential diagnosis". Clin Res Cardiol. 99 (8): 519–26. doi:10.1007/s00392-010-0152-8. PMID 20464556. Unknown parameter |month= ignored (help)
  12. ↑ 12.0 12.1 Frikha Z, Abid L, Abid D; et al. (2011). "Cardiac tamponade and paroxysmal third-degree atrioventricular block revealing a primary cardiac non-Hodgkin large B-cell lymphoma of the right ventricle: a case report". J Med Case Rep. 5: 433. doi:10.1186/1752-1947-5-433. PMC 3180417. PMID 21892927.
  13. ↑ 13.0 13.1 Houchaymi Z, Helou S, Ballout J (2010). "[Pericardial tamponade and third-degree atrioventricular block revealing a primary cardiac lymphoma]". Rev Med Interne (in French). 31 (11): e4–6. doi:10.1016/j.revmed.2010.01.014. PMID 20605278. Unknown parameter |month= ignored (help)
  14. ↑ 14.0 14.1 van Cleef AN, Schuurman MJ, Busari JO (2011). "Third-degree atrioventricular block in an adolescent following acute alcohol intoxication". BMJ Case Rep. 2011. doi:10.1136/bcr.07.2011.4547. PMID 22679160.
  15. ↑ 15.0 15.1 Brvar M, Bunc M (2009). "High-degree atrioventricular block in acute ethanol poisoning: a case report". Cases J. 2: 8559. doi:10.4076/1757-1626-2-8559. PMC 2769457. PMID 19918387.
  16. ↑ 16.0 16.1 Tian Z, Fang Q, Zhao DC; et al. (2010). "[The clinico-pathological manifestation of cardiac involvement in eosinophilic diseases]". Zhonghua Nei Ke Za Zhi (in Chinese). 49 (8): 684–7. PMID 20979789. Unknown parameter |month= ignored (help)
  17. ↑ 17.0 17.1 Facenda-Lorenzo M, Hernández-Afonso J, Rodríguez-Esteban M, de León-Hernández JC, Grillo-Pérez JJ (2012). "Cardiac Manifestations in Myotonic Dystrophy Type 1 Patients Followed Using a Standard Protocol in a Specialized Unit". Rev Esp Cardiol. doi:10.1016/j.recesp.2012.08.011. PMID 23194837. Unknown parameter |month= ignored (help)
  18. ↑ 18.0 18.1 Femenía F, Arce M, Arrieta M (2010). "[Systemic sclerosis complicated with syncope and complete AV block]". Medicina (B Aires) (in Spanish; Castilian). 70 (5): 442–4. PMID 20920962.
  19. ↑ 19.0 19.1 Thakar S, Chandra P, Pednekar M, Kabalkin C, Shani J (2012). "Complete heart block following a blow on the chest by a soccer ball: a rare manifestation of commotio cordis". Ann Noninvasive Electrocardiol. 17 (3): 280–2. doi:10.1111/j.1542-474X.2012.00518.x. PMID 22816548. Unknown parameter |month= ignored (help)
  20. ↑ 20.0 20.1 Portet N, Riu B, Bounes V, Minville V, Fourcade O (2012). "Left ventricular-right atrial communication with third-degree atrioventricular block after thoracic trauma". J Emerg Med. 43 (6): e385–8. doi:10.1016/j.jemermed.2010.11.059. PMID 21621364. Unknown parameter |month= ignored (help)


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