First-Degree Atrioventricular Block Clinical Presentation

  • Author: Jamshid Alaeddini, MD, FACC; Chief Editor: Jeffrey N Rottman, MD   more...
 
Updated: Jun 29, 2011
 

History

Patients with first-degree atrioventricular (AV) block are generally asymptomatic at rest. Markedly prolonged PR interval may reduce exercise tolerance in some patients with left ventricular systolic dysfunction. Syncope may result from transient high-degree AV block, especially in those with infranodal block and wide QRS complex.

Patients may have a history of past heart disease, including myocarditis or myocardial infarction (MI). Patients may be highly conditioned athletes with a high degree of vagal tone, or they may be on medications that slow conduction through the atrioventricular node (AVN).

A history of an infectious disease, such as Lyme disease, may be present. Asymptomatic first-degree heart block is part of the spectrum of presentation of Lyme carditis in children. Lyme carditis is most likely in children with Lyme disease who are older than 10 years of age, those with arthralgias, and those with cardiopulmonary symptoms.[10]

Borderline first-degree AV block in patients with long-standing systemic lupus erythematosus (SLE) may be a clue to more significant cardiac disease, resulting from the progression of SLE; these patients require careful screening for underlying myocardial disease.[12] Conduction disturbances may also be secondary to drugs used to treat SLE.

Patients who have undergone mitral valve replacement or mitral valve annuloplasty may have heart block postoperatively.[13]

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Physical Examination

No findings on the physical examination are specifically associated with first-degree AV block; it is generally an incidental finding noted on an electrocardiogram (ECG).

The intensity of the first heart sound (S1) is decreased in patients with first-degree AV block. Patients with first-degree AV block may have a short, soft, blowing, diastolic murmur heard at the cardiac apex. This diastolic murmur is not caused by diastolic mitral regurgitation, because it reaches its peak before the onset of regurgitation. The diastolic murmur is thought to be related to antegrade flow through closing mitral valve leaflets that are stiffer than normal.[14] Administration of atropine may reduce the duration of this murmur by shortening the PR interval.

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Complications

Patients with first-degree AV block can occasionally progress to higher-grade AV blocks. Usually, such a progression is only to Mobitz I second-degree heart block, but occasionally, higher-grade block can occur. The later scenario is particularly seen in patients with an acute MI, myocarditis, or acute drug overdoses.

Drugs that slow conduction through the AVN system increase the risk of progression to higher-grade heart blocks. Administering such agents to a person with a coexisting first-degree AV block should be done with caution.

Other potential complications include the following:

  • Reduction in left ventricular stroke volume and cardiac output
  • Pacemaker syndrome
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Contributor Information and Disclosures
Author

Jamshid Alaeddini, MD, FACC  Clinical Cardiac Electrophysiologist, Inland Cardiology Associates

Jamshid Alaeddini, MD, FACC is a member of the following medical societies: American College of Cardiology and American Heart Association

Disclosure: Boston Scientific Honoraria Speaking and teaching; Medtronic Honoraria Speaking and teaching; St. Jude Honoraria Speaking and teaching; Reliant Honoraria Speaking and teaching

Coauthor(s)

Theodore J Gaeta, DO, MPH, FACEP  Clinical Associate Professor, Department of Emergency Medicine, Weill Cornell Medical College; Vice Chairman and Program Director of Emergency Medicine Residency Program, Department of Emergency Medicine, New York Methodist Hospital; Academic Chair, Adjunct Professor, Department of Emergency Medicine, St George's University School of Medicine

Theodore J Gaeta, DO, MPH, FACEP is a member of the following medical societies: Alliance for Clinical Education, American College of Emergency Physicians, Clerkship Directors in Emergency Medicine, Council of Emergency Medicine Residency Directors, New York Academy of Medicine, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Michael D Levine, MD  Physician, Department of Medical Toxicology, Banner Good Samaritan Medical Center; Physician, Department of Emergency Medicine, Banner Thunderbird Medical Center

Michael D Levine, MD is a member of the following medical societies: Alpha Omega Alpha, American College of Emergency Physicians, American College of Medical Toxicology, American Medical Association, Emergency Medicine Residents Association, Phi Beta Kappa, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Jamshid Shirani, MD  Director of Cardiology Fellowship Program, Director of Echocardiography Laboratory, St Luke's Hospital and Health Network

Jamshid Shirani, MD is a member of the following medical societies: American Association for the Advancement of Science, American College of Cardiology, American College of Physicians, American Federation for Medical Research, American Heart Association, American Society of Echocardiography, and Association of Subspecialty Professors

Disclosure: Nothing to disclose.

Specialty Editor Board

Eddy S Lang, MDCM, CCFP(EM), CSPQ  Associate Professor, Senior Researcher, Division of Emergency Medicine, Department of Family Medicine, University of Calgary Faculty of Medicine; Assistant Professor, Department of Family Medicine, McGill University Faculty of Medicine, Canada

Eddy S Lang, MDCM, CCFP(EM), CSPQ is a member of the following medical societies: American College of Emergency Physicians, Canadian Association of Emergency Physicians, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Francisco Talavera, PharmD, PhD  Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Medscape Salary Employment

Brian Olshansky, MD  Professor of Medicine, Department of Internal Medicine, University of Iowa College of Medicine

Brian Olshansky, MD is a member of the following medical societies: American Autonomic Society, American College of Cardiology, American College of Chest Physicians, American College of Physicians, American College of Sports Medicine, American Federation for Clinical Research, American Heart Association, Cardiac Electrophysiology Society, Heart Rhythm Society, and New York Academy of Sciences

Disclosure: Guidant/Boston Scientific Honoraria Speaking and teaching; Medtronic Honoraria Speaking and teaching; Guidant/Boston Scientific Consulting fee Consulting; Novartis Honoraria Speaking and teaching; Novartis Consulting fee Consulting

David FM Brown, MD  Associate Professor, Division of Emergency Medicine, Harvard Medical School; Vice Chair, Department of Emergency Medicine, Massachusetts General Hospital

David FM Brown, MD is a member of the following medical societies: American College of Emergency Physicians and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Chief Editor

Jeffrey N Rottman, MD  Professor of Medicine and Pharmacology, Vanderbilt University School of Medicine; Chief, Department of Cardiology, Nashville Veterans Affairs Medical Center

Jeffrey N Rottman, MD is a member of the following medical societies: American Heart Association and North American Society of Pacing and Electrophysiology (NASPE)

Disclosure: Nothing to disclose.

References

  1. John AD, Fleisher LA. Electrocardiography: the ECG. Anesthesiol Clin. Dec 2006;24(4):697-715, v-vi. [Medline].

  2. Barold SS, Ilercil A, Leonelli F, Herweg B. First-degree atrioventricular block. Clinical manifestations, indications for pacing, pacemaker management & consequences during cardiac resynchronization. J Interv Card Electrophysiol. Nov 2006;17(2):139-52. [Medline].

  3. Sherron P, Torres-Arraut E, Tamer D, Garcia OL, Wolff GS. Site of conduction delay and electrophysiologic significance of first-degree atrioventricular block in children with heart disease. Am J Cardiol. May 1 1985;55(11):1323-7. [Medline].

  4. Berger PB, Ruocco NA, Ryan TJ, et al. Incidence and prognostic implications of heart block complicating inferior myocardial infarction treated with thrombolytic therapy: results from TIMI II. J Am Coll Cardiol. Sep 1992;20(3):533-40. [Medline].

  5. Sonesson SE, Salomonsson S, Jacobsson LA, et al. Signs of first-degree heart block occur in one-third of fetuses of pregnant women with anti-SSA/Ro 52-kd antibodies. Arthritis Rheum. Apr 2004;50(4):1253-61. [Medline].

  6. Alkoutami GS, Reeves WC, Movahed A. The safety of adenosine pharmacologic stress testing in patients with first-degree atrioventricular block in the presence and absence of atrioventricular blocking medications. J Nucl Cardiol. Sep-Oct 1999;6(5):495-7. [Medline].

  7. Suda K, Raboisson MJ, Piette E, et al. Reversible atrioventricular block associated with closure of atrial septal defects using the Amplatzer device. J Am Coll Cardiol. May 5 2004;43(9):1677-82. [Medline].

  8. Upshaw CB Jr. Comparison of the prevalence of first-degree atrioventricular block in African-American and in Caucasian patients: an electrocardiographic study III. J Natl Med Assoc. Jun 2004;96(6):756-60. [Medline].

  9. Mymin D, Mathewson FA, Tate RB, Manfreda J. The natural history of primary first-degree atrioventricular heart block. N Engl J Med. Nov 6 1986;315(19):1183-7. [Medline].

  10. Costello JM, Alexander ME, Greco KM, Perez-Atayde AR, Laussen PC. Lyme carditis in children: presentation, predictive factors, and clinical course. Pediatrics. May 2009;123(5):e835-41. [Medline].

  11. Cheng S, Keyes MJ, Larson MG, McCabe EL, Newton-Cheh C, Levy D, et al. Long-term outcomes in individuals with prolonged PR interval or first-degree atrioventricular block. JAMA. Jun 24 2009;301(24):2571-7. [Medline]. [Full Text].

  12. Makaryus JN, Catanzaro JN, Goldberg S, Makaryus AN. Rapid progression of atrioventricular nodal blockade in a patient with systemic lupus erythematosus. Am J Emerg Med. Oct 2008;26(8):967.e5-7. [Medline].

  13. Berdajs D, Schurr UP, Wagner A, Seifert B, Turina MI, Genoni M. Incidence and pathophysiology of atrioventricular block following mitral valve replacement and ring annuloplasty. Eur J Cardiothorac Surg. Jul 2008;34(1):55-61. [Medline].

  14. Schnittger I, Appleton CP, Hatle LK, Popp RL. Diastolic mitral and tricuspid regurgitation by Doppler echocardiography in patients with atrioventricular block: new insight into the mechanism of atrioventricular valve closure. J Am Coll Cardiol. Jan 1988;11(1):83-8. [Medline].

  15. Epstein AE, DiMarco JP, Ellenbogen KA, Estes NA 3rd, Freedman RA, Gettes LS, et al. ACC/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the ACC/AHA/NASPE 2002 Guideline Update for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices) developed in collaboration with the American Association for Thoracic Surgery and Society of Thoracic Surgeons. J Am Coll Cardiol. May 27 2008;51(21):e1-62. [Medline].

 
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The PR interval is 0.24 seconds (240 ms) in this patient with asymptomatic first-degree atrioventricular block.
ECG in a patient with first-degree heart block.
ECG in patient with first-degree heart block.
 
 
 
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