eMedicine Specialties > Cardiology > Arrhythmias

Electrical Alternans: Differential Diagnoses & Workup

Author: Eric Gorgon Shaw, MD, FACEP, FAAEM, Staff Physician, Department of Emergency Medicine, Lewis County General Hospital
Coauthor(s): Michael R Gold, MD, PhD, Director, Professor, Division of Cardiology, Medical University of South Carolina; Amal Mattu, MD, FACEP, FAAEM, Program Director, Emergency Medicine Residency, Co-Director, Emergency Medicine/Internal Medicine Combined Residency Program, Department of Surgery, Division of Emergency Medicine, University of Maryland School of Medicine
Contributor Information and Disclosures

Updated: Aug 26, 2008

Differential Diagnoses

Atrial Fibrillation
Second-Degree Atrioventricular Block
Atrial Flutter
Sinus Node Dysfunction
Atrial Tachycardia
Torsade de Pointes
Atrioventricular Block
Ventricular Fibrillation
Atrioventricular Dissociation
Ventricular Tachycardia
Atrioventricular Nodal Reentry Tachycardia (AVNRT)
Wolff-Parkinson-White Syndrome
First-Degree Atrioventricular Block
Long QT Syndrome

Workup

Laboratory Studies

Direct laboratory investigations toward discovery of the primary underlying etiology of electrical alternans. Based on other clinical information, appropriate lab studies include cardiac enzymes for myocardial ischemia and infarction as well as serum calcium, potassium, and magnesium if electrolyte abnormalities are suspected. In the setting of a large pericardial effusion, laboratory studies searching for a malignancy may be warranted.

Imaging Studies

  • Chest radiography
    • Chest radiograph may reveal an enlarged cardiac silhouette, possibly indicating cardiomyopathy or large pericardial effusion.
    • Evidence of the Westermark sign or Hampton hump may suggest pulmonary embolism as the cause of electrical alternans.
  • Echocardiography
    • Echocardiography should be performed on those patients with total electrical alternans (P, QRS, and T wave) to evaluate for pericardial effusion.
    • Echocardiography is also necessary for evaluation of patients with hypertrophic cardiomyopathy, alcoholic cardiomyopathy, or congestive heart failure.

Other Tests

  • Electrocardiogram
    • ECG is the main study through which electrical alternans is discovered. Any or all components of the electrical waveforms may exhibit alternans (see Media files 1-2).
    • High-resolution ECG with spectral analysis can detect alternans in the microvolt range of amplitude. This detailed study is appropriate when searching for T-wave alternans as a predictor of ventricular tachyarrhythmia events.5
    • Routine ambulatory ECG monitoring of T-wave alternans, using dynamic, nonspectral, modified moving average analysis, may be helpful for risk stratification for arrhythmias.
    • T-wave alternans may be seen best in lead V 2 .
    • T-wave alternans can be detected by use of implantable cardioverter-defibrillators (ICDs).6

Procedures

  • Electrical alternans due to a large pericardial effusion should resolve completely after the effusion is drained. Pericardiocentesis must be performed emergently in the setting of cardiac tamponade.
  • In selected cases, cardiac catheterization may be indicated to further evaluate those patients with suspected vasospastic or nonvasospastic angina pectoris.

More on Electrical Alternans

Overview: Electrical Alternans
Differential Diagnoses & Workup: Electrical Alternans
Treatment & Medication: Electrical Alternans
Follow-up: Electrical Alternans
Multimedia: Electrical Alternans
References
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References

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  6. Paz O, Zhou X, Gillberg J, Tseng HJ, Gang E, Swerdlow C. Detection of T-wave alternans using an implantable cardioverter-defibrillator. Heart Rhythm. Jul 2006;3(7):791-7. [Medline].

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Further Reading

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Keywords

mechanical alternans, pulsus alternans, repolarization alternans, conduction and refractoriness alternans, alternans due to cardiac motion, repolarization or conduction abnormality of the Purkinje fibers or myocardium, vasospastic angina pectoris, acute myocardial infarction, nonvasospastic angina pectoris, congenital long QT syndrome, hypocalcemia, hypokalemia, hypomagnesemia, hypertrophic cardiomyopathy, alcoholic cardiomyopathy, congestive heart failure, acute pulmonary embolism, cardiac resuscitation, myocardial ischemia, atrial fibrillation, Wolff-Parkinson-White syndrome, rheumatic heart disease, acute pulmonary embolism, myocardial contusion, left ventricular dysfunction, large pericardial effusion, hypertrophic cardiomyopathy

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Contributor Information and Disclosures

Author

Eric Gorgon Shaw, MD, FACEP, FAAEM, Staff Physician, Department of Emergency Medicine, Lewis County General Hospital
Eric Gorgon Shaw, MD, FACEP, FAAEM is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, and Wilderness Medical Society
Disclosure: Nothing to disclose.

Coauthor(s)

Michael R Gold, MD, PhD, Director, Professor, Division of Cardiology, Medical University of South Carolina
Michael R Gold, MD, PhD is a member of the following medical societies: Alpha Omega Alpha, American College of Cardiology, American College of Chest Physicians, and American Heart Association
Disclosure: Nothing to disclose.

Amal Mattu, MD, FACEP, FAAEM, Program Director, Emergency Medicine Residency, Co-Director, Emergency Medicine/Internal Medicine Combined Residency Program, Department of Surgery, Division of Emergency Medicine, University of Maryland School of Medicine
Amal Mattu, MD, FACEP, FAAEM is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Medical Editor

Robert E Fowles, MD, Clinical Professor of Medicine, University of Utah College of Medicine; Consulting Staff, Intermountain Medical Center and LDS Hospital; Director and Consulting Staff, Department of Cardiology, Salt Lake Clinic
Robert E Fowles, MD is a member of the following medical societies: American College of Cardiology, American College of Physicians, and American Heart Association
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Steven J Compton, MD, FACC, FACP, Director of Cardiac Electrophysiology, Alaska Heart Institute, Providence and Alaska Regional Hospitals
Steven J Compton, MD, FACC, FACP is a member of the following medical societies: Alaska State Medical Association, American College of Cardiology, American College of Physicians, and Heart Rhythm Society
Disclosure: Nothing to disclose.

CME Editor

Amer Suleman, MD, Consultant in Electrophysiology and Cardiovascular Medicine, Department of Internal Medicine, Division of Cardiology, Medical City Dallas Hospital
Amer Suleman, MD is a member of the following medical societies: American College of Physicians, American Heart Association, American Institute of Stress, American Society of Hypertension, Federation of American Societies for Experimental Biology, Royal Society of Medicine, and Society of Cardiac Angiography and Interventions
Disclosure: Nothing to disclose.

Chief Editor

J Paul Mounsey, MD, PhD, MRCP, Professor of Medicine, Director, Cardiac Electrophysiology Service, Division of Cardiology, University of North Carolina
J Paul Mounsey, MD, PhD, MRCP is a member of the following medical societies: American College of Cardiology, American Heart Association, Heart Rhythm Society, and Royal College of Physicians of the United Kingdom
Disclosure: Medtronic Honoraria Speaking and teaching; St Jude Honoraria Speaking and teaching; Boston Scientific Honoraria Speaking and teaching

 
 
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