Bigeminy
| Bigeminy | |
|---|---|
| Other names: Bigemini | |
 | |
| Ventricular bigeminy seen on a 12 lead ECG | |
 | |
| Pronunciation |
|
| Symptoms | None, feeling of skipped beats[1][2] |
| Complications | Ventricular tachycardia[3] |
| Types | Ventricular, junctional, atrial[4] |
| Risk factors | Stimulants (stress, caffeine, cocaine); alcohol; high thyroid; low oxygen (coronary artery disease, pulmonary embolism, drowning); low potassium; digoxin toxicity; mitral valve prolapse; myocarditis[4][5] |
| Diagnostic method | ECG[6] |
| Differential diagnosis | Trigeminy, second degree heart block[6][3] |
| Treatment | None, beta-blockers, calcium channel blockers, catheter ablation[5] |
| Prognosis | Generally good[2] |
| Frequency | Relatively common[3] |
Bigeminy is a heart arrhythmia in which, following each regular heartbeat, there is a single ectopic beat (irregular heartbeat).[7] There are three types ventricular, junctional, and atrial.[4] Generally there are no significant symptoms; though, there may be feelings of a skipped beat.[1][2] Rarely, low blood pressure and lightheadedness may occur.[8]
Causes include stimulants (psychological stress, caffeine, cocaine); alcohol; high thyroid; low oxygen (coronary artery disease, pulmonary embolism, drowning); low potassium; digoxin toxicity; mitral valve prolapse; and myocarditis.[4][5] Diagnosis is by 12-lead electrocardiogram (ECG).[6] In ventricular bigeminy, each sinus beat is followed by a premature ventricular contraction (PVC), than a pause, another normal beat, and then another PVC.[9][10] In atrial and junctional bigeminy, the second beat is a premature atrial contraction (PAC) or premature junctional contraction respectively.[4]
Outcomes are similar to that of PVCs.[1] If there are more than six PVCs per minute, which is the case in bigeminy, investigations should be performed looking for an underlying cause.[4] Those without symptoms do not generally require specific treatment; otherwise, beta-blockers, calcium channel blockers, or catheter ablation may be carried out.[5] Outcomes are generally good; though, occasionally ventricular tachycardia can occur.[3][2] Bigeminy is relatively common.[3]
Signs and symptoms
Symptoms can include a bigeminal pulse which is when alternate pulses are abnormally weaker and not at regular interval. It is mainly due to abnormal alternate beats , which may be result of ectopic beats. Ectopic beats may be atrial or ventricular in origin. Atrial bigeminy or ventricular bigeminy can both give rise to bigeminal pulse. Similar features between bigeminal pulse and pulsus alternans are strong peak and weak peak. However, unlike pulsus alternans, the weak beat in bigeminal pulse occurs prematurely . Thus, not followed a pause as it is in pulsus alternans but occurs close to normal strong beat. [11]
Cause
After any PVC there is a pause that can lead to the development of bigeminy. A PVC wavefront often encounters a refractory AV node that does not conduct the wavefront retrograde. Thus the atrium is not depolarized and the sinus node is not reset. Since the sinus P wave to PVC interval is less than the normal P–P interval, the interval between the PVC and the next P wave is prolonged to equal the normal time elapsed during two P–P intervals. This is called a "compensatory" pause. The pause after the PVC leads to a longer recovery time, which is associated with a higher likelihood of myocardium being in different stages of repolarization. This then allows for re-entrant circuits and sets up the ventricle for another PVC after the next sinus beat.[12] The constant interval between the sinus beat and PVC suggests a reentrant etiology rather than spontaneous automaticity of the ventricle.[13]
Premature atrial contractions by contrast do not have a compensatory pause, since they reset the sinus node, but atrial or supraventricular bigeminy can occur. If the PACs are very premature, the wavefront can encounter a refractory AV node and not be conducted. This can be mistaken for sinus bradycardia if the PAC is buried in the T wave since the PAC will reset the SA node and lead to a long P–P interval.[12]
Diagnosis
Rule of bigeminy
When the atrial rhythm is irregular (as in atrial fibrillation or sinus arrythmia) the presence of bigeminy depends on the length of the P–P interval and happens more frequently with a longer interval. As with post PVC pauses, a longer P–P interval leads to a higher chance of re-entrant circuits and thus PVCs. The term "rule of bigeminy" is used to refer to the dependence of bigeminy on the ventricular cycle length in irregular rhythms.[13]
Classification
There can be similar patterns depending on the frequency of abnormal beats. If every other beat is abnormal, it is described as bigeminal. If every third beat is aberrant, it is trigeminal; every fourth would be quadrigeminal. Typically, if every fifth or more beat is abnormal, the aberrant beat would be termed occasional.[9]
Bigeminy is contrasted with couplets, which are paired abnormal beats. Groups of three abnormal beats are called triplets and are considered a brief run of non-sustained ventricular tachycardia (NSVT), and if the grouping lasts for more than 30 seconds, it is ventricular tachycardia (VT).[12]
Treatment
In people without underlying heart disease and who do not have any symptoms, bigeminy in itself does not require specific treatment.[5] If symptoms are present, beta-blockers can be used to try to suppress ventricular ectopy.[5] Class I and III agents are generally avoided as they can provoke more serious arrhythmias.[14]
Terminology
The two beats are similar to two twins (hence bi- + gemini).[10]
References
- ↑ 1.0 1.1 1.2 Manolis, Antonis (March 2024). "Premature ventricular complexes: Clinical presentation and diagnostic evaluation". www.uptodate.com. UpToDate. Archived from the original on 26 October 2023. Retrieved 22 April 2024.
- ↑ 2.0 2.1 2.2 2.3 Levine, Glenn N. (30 June 2013). Arrhythmias 101. JP Medical Ltd. p. 79. ISBN 978-93-5090-499-2. Archived from the original on 23 April 2024. Retrieved 22 April 2024.
- ↑ 3.0 3.1 3.2 3.3 3.4 Wang, K; Asinger, RW; Marriott, HJ (April 2007). "Bigeminal rhythms, common and uncommon mechanisms". Journal of electrocardiology. 40 (2): 135–8. doi:10.1016/j.jelectrocard.2006.04.005. PMID 17070536.
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 Dubin, Dale (2000). Rapid Interpretation of EKG's: An Interactive Course. Cover Publishing Company. p. 123-139. ISBN 978-0-912912-06-6. Archived from the original on 2024-04-23. Retrieved 22 April 2024.
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 "Bigeminy: Causes, Symptoms & Treatment". Cleveland Clinic. Archived from the original on 18 March 2023. Retrieved 22 April 2024.
- ↑ 6.0 6.1 6.2 Farzam, K; Richards, JR (January 2024). "Premature Ventricular Contraction". StatPearls. PMID 30422584.
- ↑ Hebbar, AK; Hueston, WJ (15 June 2002). "Management of common arrhythmias: Part II. Ventricular arrhythmias and arrhythmias in special populations". American family physician. 65 (12): 2491–6. PMID 12086238. Archived from the original on 24 September 2023. Retrieved 22 April 2024.
- ↑ Benditt, David (March 2024). "Syncope in adults: Epidemiology, pathogenesis, and etiologies". www.uptodate.com. UpToDate. Archived from the original on 23 April 2024. Retrieved 22 April 2024.
- ↑ 9.0 9.1 Shvilkin, Ary L. Goldberger, Zachary D. Goldberger, Alexei (2013). Goldberger's Clinical Electrocardiography: A Simplified Approach (8th ed.). Philadelphia, PA: Elsevier/Saunders. ISBN 9780323087865.
- ↑ 10.0 10.1 Mond, HG; Haqqani, HM (July 2020). "The Electrocardiographic Footprints of Ventricular Ectopy". Heart, lung & circulation. 29 (7): 988–999. doi:10.1016/j.hlc.2020.01.002. PMID 32063472.
- ↑ Raju, B.S. (2003). Clinical Methods in Cardiology. Orient Blackswan. p. 189. ISBN 978-81-250-2179-7. Archived from the original on 2024-04-23. Retrieved 2024-04-22.
- ↑ 12.0 12.1 12.2 Wagner, Galen S. (2001). Marriott's Practical Electrocardiography (10th ed.). Philadelphia, PA: Williams & Wilkins. ISBN 0683307460.
- ↑ 13.0 13.1 Langendorf, R.; Pick, A.; Winternitz, M. (1 March 1955). "Mechanisms of Intermittent Ventricular Bigeminy: I. Appearance of Ectopic Beats Dependent Upon Length of the Ventricular Cycle, the "Rule of Bigeminy"". Circulation. 11 (3): 422–430. doi:10.1161/01.CIR.11.3.422. PMID 14352386.
- ↑ Papadakis, Maxine A.; Stephen J. McPhee; Michael W. Rabow, eds. (2013). Current Medical Diagnosis and Treatment 2014 (53 ed.). New York: McGraw-Hill Medical. ISBN 9780071806336.