History

Fact Explanation
Symptoms of first degree heart block First degree heart block is usually asymptomatic. Patients may develop dyspnea, chest pain and syncope with exertion. [3]
Symptoms of second degree heart block Second degree heart block can also be asymptomatic sometimes. [3] Recurrent syncope or presyncope is another presentation of second degree heart block. [1]
Symptoms of third degree heart block Patients with third degree heart block can present with recurrent syncope or presyncope. In complete heart block light headedness and dizziness are also usual complains. These symptoms are due to reduced cerebral perfusion secondary to bradycardia. [1] Fatigue is commonly seen in patients with complete heart block. [5]
History of myocarditis or myocardial infarction Patients who had a history of myocarditis or myocardial infarction can later present with first degree atrio-ventricular block. [4,7]
Irregular heart beat Patients with atrio-ventricular block may complain of irregular heartbeat. [5]
Drug history Certain drugs (digitalis, beta-blockers, and calcium channel blockers) can cause slow transmission through the atrioventricular node. [2,7]
Angina [5] Patients with a history of ischemic heart diseases may complain of frequent ischemic chest pain because bradycardia can precipitate angina.
Sudden death [6] Sudden death can occur due to asystole or secondary to ventricular tachyarrhythmias.
References
  1. GREGORATOS G., CHEITLIN M. D., CONILL A., EPSTEIN A. E., FELLOWS C., FERGUSON T. B., FREEDMAN R. A., HLATKY M. A., NACCARELLI G. V., SAKSENA S., SCHLANT R. C., SILKA M. J.. ACC/AHA Guidelines for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices: Executive Summary : A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Pacemaker Implantation). Circulation [online] 1998 April, 97(13):1325-1335 [viewed 27 June 2014] Available from: doi:10.1161/01.CIR.97.13.1325
  2. MERIDETH J., PRUITT R. D.. Disturbances in Cardiac Conduction and their Management. Circulation [online] 1973 May, 47(5):1098-1107 [viewed 27 June 2014] Available from: doi:10.1161/01.CIR.47.5.1098
  3. Asymptomatic complete heart block. Br Med J [online] 1979 Nov 17, 2(6200):1245-1246 [viewed 27 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1596880
  4. HANAWA H, IZUMI T, SAITO Y, OCHIAI Y, OKURA Y, INOMATA T, HIRONO S, OGAWA Y, SAITO R, KODAMA M, HIGUMA N, AIZAWA Y. Recovery from complete atrioventricular block caused by idiopathic giant cell myocarditis after corticosteroid therapy. Jpn Circ J [online] 1998 Mar, 62(3):211-4 [viewed 27 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/9583449
  5. RAVIELE A., GIADA F., BERGFELDT L., BLANC J. J., BLOMSTROM-LUNDQVIST C., MONT L., MORGAN J. M., RAATIKAINEN M. J. P., STEINBECK G., VISKIN S., KIRCHHOF P., BRAUNSCHWEIG F., BORGGREFE M., HOCINI M., BELLA P. D., SHAH D. C.. Management of patients with palpitations: a position paper from the European Heart Rhythm Association. Europace [online] December, 13(7):920-934 [viewed 27 June 2014] Available from: doi:10.1093/europace/eur130
  6. FRIEDMAN R. A.. Congenital AV Block : Pace Me Now or Pace Me Later?. Circulation [online] 1995 August, 92(3):283-285 [viewed 27 June 2014] Available from: doi:10.1161/01.CIR.92.3.283
  7. DECHERD GM, RUSKIN A. THE MECHANISM OF THE WENCKEBACH TYPE OF A-V BLOCK Br Heart J [online] 1946 Jan, 8(1):6-16 [viewed 27 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC503564

Examination

Fact Explanation
Signs of first degree heart block Cardiovascular examination can be normal in first degree atrioventricular block.
Signs of second degree heart block Bradycardia and irregular pulse can be detected. [1]
Signs of third degree heart block In third degree heart block, the right atrium can contract against the closed tricuspid valve. This results in appearance of cannon a waves in jugular venous pulsations. [2]
References
  1. SILVERMAN M. E.. Woldemar Mobitz and His 1924 Classification of Second-Degree Atrioventricular Block. Circulation [online] 2004 August, 110(9):1162-1167 [viewed 27 June 2014] Available from: doi:10.1161/01.CIR.0000140669.35049.34
  2. CHEN D., PAI P.-Y.. Cannon A Wave. Circulation [online] 2009 April, 119(13):e381-e383 [viewed 27 June 2014] Available from: doi:10.1161/CIRCULATIONAHA.108.833095

Differential Diagnoses

Fact Explanation
Acute coronary syndrome Chest pain is common in both conditions. Patients complain of constricting type left sided chest pain, which radiates to the left arm and jaw. [1]
Syncope Bradyarrhythmia, tachyarrhythmia (supraventricular tachycardia, ventricular tachycardia, ventricular fibrillation) hypertrophic cardiomyopathy and aortic stenosis are common cardiac causes of syncope. [4]
Sudden cardiac death Short history of (usually less than 1hour) chest pain, palpitations and dyspnea is common. [2]
Chagas Disease Cardiac complications of chronic Chagas disease include cardiomyopathy, heart failure and altered heart rate or rhythm, and cardiac arrest. [3]
References
  1. KRISTIAN THYGESEN, JOSEPH S. ALPERT, HARVEY D. Universal definition of myocardial infarction. Eur Heart J. [online] 2007; 28 (20): 2525-2538. [viewed 20 June 2014]. Available from: doi: 10.1093/eurheartj/ehm355
  2. ZIPES D. P., WELLENS H. J. J.. Sudden Cardiac Death. Circulation [online] 1998 November, 98(21):2334-2351 [viewed 25 June 2014] Available from: doi:10.1161/01.CIR.98.21.2334
  3. ANIS RASSI, JOSÉ ANTONIO MARIN-NETO. Chagas disease. The Lancet [online] 17 April 2010: 375 (9723) 1388 – 1402. [viewed 14 May 2014] Available from: doi:10.1016/S0140-6736(10)60061-X
  4. SHUKLA G. J.. Syncope. Circulation [online] 2006 April, 113(16):e715-e717 [viewed 27 June 2014] Available from: doi:10.1161/CIRCULATIONAHA.105.602250

Investigations - for Diagnosis

Fact Explanation
ECG In first degree heart block every P wave is followed by a QRS complex but the P-R interval is 0.21 sec or more. [1] Mobitz type 1 and 2 are two types of second degree heart block. In Wenckebach phenomenon (Mobitz type I) PR interval progressively increases and there is a P wave which is not followed by a QRS complex. These ECG changes repeat cyclically. [2,9] In Mobitz type two second degree heart block constant P-R interval is followed by a non-conducted QRS complex. [10] In complete heart block there are more P waves than the QRS complexes, and there is no relationship between the P and QRS complexes. The ventricular beat may arise within the atrio-ventricular node resulting in narrow complex QRS waves and below the atrio-ventricular node resulting in wide QRS complexes. [8]
Holter monitoring If the ECG shows no abnormality it is better to proceed with a 24 hour Holter monitoring in order to identify transient atrio-ventricular blocks. [3]
Electrophysiologic testing This is an invasive procedure and can detect conduction abnormalities in His bundles. [4]
Exercise ECG Exercise ECG helps in detecting exercise induced arrhythmias. [5]
Serum electrolytes Electrolyte abnormalities can also cause reversible atrioventricular blocks. [7,11]
Thyroid function test Thyroid function abnormalities can cause atrio-ventricular block. [6]
References
  1. MERIDETH J., PRUITT R. D.. Disturbances in Cardiac Conduction and their Management. Circulation [online] 1973 May, 47(5):1098-1107 [viewed 27 June 2014] Available from: doi:10.1161/01.CIR.47.5.1098
  2. SILVERMAN M. E.. Woldemar Mobitz and His 1924 Classification of Second-Degree Atrioventricular Block. Circulation [online] 2004 August, 110(9):1162-1167 [viewed 27 June 2014] Available from: doi:10.1161/01.CIR.0000140669.35049.34
  3. STRICKBERGER S. A.. AHA/ACCF Scientific Statement on the Evaluation of Syncope: From the American Heart Association Councils on Clinical Cardiology, Cardiovascular Nursing, Cardiovascular Disease in the Young, and Stroke, and the Quality of Care and Outcomes Research Interdisciplinary Working Group; and the American College of Cardiology Foundation: In Collaboration With the Heart Rhythm Society: Endorsed by the American Autonomic Society. Circulation [online] 2006 January, 113(2):316-327 [viewed 27 June 2014] Available from: doi:10.1161/CIRCULATIONAHA.105.170274
  4. BRIGNOLE M., MENOZZI C., MOYA A., GARCIA-CIVERA R., MONT L., ALVAREZ M., ERRAZQUIN F., BEIRAS J., BOTTONI N., DONATEO P.. Mechanism of Syncope in Patients With Bundle Branch Block and Negative Electrophysiological Test. Circulation [online] 2001 October, 104(17):2045-2050 [viewed 27 June 2014] Available from: doi:10.1161/hc4201.097837
  5. WOELFEL ALAN K., SIMPSON ROSS J., GETTES LEONARD S., FOSTER JAMES R.. Exercise-induced distal atrioventricular block. Journal of the American College of Cardiology [online] 1983 September, 2(3):578-581 [viewed 27 June 2014] Available from: doi:10.1016/S0735-1097(83)80288-5
  6. OZCAN KS, OSMONOV D, ERDINLER I, ALTAY S, YILDIRIM E, TURKKAN C, HASDEMIR H, CAKMAK N, ALPER AT, SATILMIS S, GURKAN K. Atrioventricular block in patients with thyroid dysfunction: prognosis after treatment with hormone supplementation or antithyroid medication. J Cardiol [online] 2012 Oct, 60(4):327-32 [viewed 27 June 2014] Available from: doi:10.1016/j.jjcc.2012.05.012
  7. Part 10.1: Life-Threatening Electrolyte Abnormalities. Circulation [online] 2005 November, 112(24_suppl):IV-121-IV-125 [viewed 27 June 2014] Available from: doi:10.1161/CIRCULATIONAHA.105.166563
  8. LEVIS JT. ECG Diagnosis: Complete Heart Block Perm J [online] 2011, 15(2):90 [viewed 27 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3140757
  9. DECHERD GM, RUSKIN A. THE MECHANISM OF THE WENCKEBACH TYPE OF A-V BLOCK Br Heart J [online] 1946 Jan, 8(1):6-16 [viewed 27 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC503564
  10. SPEAR J. F., MOORE E. N.. Electrophysiologic Studies on Mobitz Type II Second-Degree Heart Block. Circulation [online] 1971 December, 44(6):1087-1095 [viewed 27 June 2014] Available from: doi:10.1161/01.CIR.44.6.1087
  11. WOOD M. A.. Cardiac Pacemakers From the Patient's Perspective. [online] 2002 May, 105(18):2136-2138 [viewed 27 June 2014] Available from: doi:10.1161/01.CIR.0000016183.07898.90

Investigations - Followup

Fact Explanation
ECG Patients with first degree heart block need long term monitoring because of the reason it may progress to second degree heart block. [1]
Holter monitoring This is also recommended for patients with first degree heart block for the above mentioned reason. [1]
References
  1. GREGORATOS G. Indications and recommendations for pacemaker therapy. Am Fam Physician [online] 2005 Apr 15, 71(8):1563-70 [viewed 27 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/15864898

Management - General Measures

Fact Explanation
Health education First degree heart block usually does not require any treatment. Once a pacemaker is inserted patient should avoid weight lifting from the ipsilateral arm for about 4 to 6 weeks. Patients should be followed up in every 3 to 6 months. [1]
Stop or change any offending drugs Digitalis and calcium channel blockers can cause atrio-ventricular block. [2] If recognised the drug should be stopped.
Correct any electrolyte imbalance Electrolyte imbalance is a potentially reversible cause of atrio-ventricular block. [1]
References
  1. WOOD M. A.. Cardiac Pacemakers From the Patient's Perspective. [online] 2002 May, 105(18):2136-2138 [viewed 27 June 2014] Available from: doi:10.1161/01.CIR.0000016183.07898.90
  2. DECHERD GM, RUSKIN A. THE MECHANISM OF THE WENCKEBACH TYPE OF A-V BLOCK Br Heart J [online] 1946 Jan, 8(1):6-16 [viewed 27 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC503564

Management - Specific Treatments

Fact Explanation
Conservative management Patients with first degree atrio-ventricular block are usually asymptomatic and does not require any treatment. [6]
Permanent pacing [1] Temporary transcutaneous or transvenous pacing may be needed in emergency situations. [4] For first degree heart block permanent pacing is considered if they have congestive heart failure or left ventricular dysfunction, because bradycardia can further compromise the cardiac function. Pacing is also considered in patients with bi-fascicular or tri-fascicular block with first degree heart block. [1] The definitive treatment for symptomatic (heart failure or ventricular arrhythmias, symptomatic bradycardia) atrio-ventricular blocks, particularly for third degree atrio-ventricular blocks is the implantation of a permanent pacemaker. In patients with second or third degree heart block permanent pacing is indicated if the asystole is greater than or equal to 3.0 seconds or if escape rate is less than 40 bpm, even the patient is asymptomatic. [1] If the patient has symptomatic heart failure with atrio-ventricular block, biventricular pacing is considered to be superior to conventional right ventricular pacing. [3,5]
Medical management Medical management has very limited role in treating atrio-ventricular block. It can be used in first degree heart block. Atropine and isoproterenol are commonly used drugs. [2,4]
References
  1. GREGORATOS G., CHEITLIN M. D., CONILL A., EPSTEIN A. E., FELLOWS C., FERGUSON T. B., FREEDMAN R. A., HLATKY M. A., NACCARELLI G. V., SAKSENA S., SCHLANT R. C., SILKA M. J.. ACC/AHA Guidelines for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices: Executive Summary : A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Pacemaker Implantation). Circulation [online] 1998 April, 97(13):1325-1335 [viewed 27 June 2014] Available from: doi:10.1161/01.CIR.97.13.1325
  2. MERIDETH J., PRUITT R. D.. Disturbances in Cardiac Conduction and their Management. Circulation [online] 1973 May, 47(5):1098-1107 [viewed 27 June 2014] Available from: doi:10.1161/01.CIR.47.5.1098
  3. CURTIS ANNE B., WORLEY SETH J., ADAMSON PHILIP B., CHUNG EUGENE S., NIAZI IMRAN, SHERFESEE LOU, SHINN TIMOTHY, ST. JOHN SUTTON MARTIN. Biventricular Pacing for Atrioventricular Block and Systolic Dysfunction. N Engl J Med [online] 2013 April, 368(17):1585-1593 [viewed 27 June 2014] Available from: doi:10.1056/NEJMoa1210356
  4. Part 7.3: Management of Symptomatic Bradycardia and Tachycardia. Circulation [online] 2005 November, 112(24_suppl):IV-67-IV-77 [viewed 27 June 2014] Available from: doi:10.1161/CIRCULATIONAHA.105.166558
  5. GREGORATOS G. Indications and recommendations for pacemaker therapy. Am Fam Physician [online] 2005 Apr 15, 71(8):1563-70 [viewed 27 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/15864898
  6. FORSBERG S. å., JUUL-MöLLER S.. Myocardial Infarction Complicated by Heart Block-Treatment and Long-Term Prognosis. [online] 2009 April, 206(1-6):483-487 [viewed 28 June 2014] Available from: doi:10.1111/j.0954-6820.1979.tb13551.x