Multifocal atrial tachycardia
Multifocal atrial tachycardia | |
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Other names | Chaotic atrial tachycardia[1] |
Multifocal atrial tachycardia | |
Specialty | Cardiology |
Multifocal (or multiform) atrial tachycardia (MAT) is an
"Multiform" refers to the observation of variable P wave shapes, while "multifocal" refers to the underlying cause. Although these terms are used interchangeably, some sources prefer "multiform" since it does not presume any underlying mechanism.
Causes
MAT usually arises because of an underlying medical condition. Its prevalence has been estimated at 3 per 1000 in adult hospital inpatients and is much rarer in paediatric practice; it is more common in the elderly, and its management and prognosis are both those of the underlying diagnosis.[4]
It is mostly common in patients with lung disorders, but it can occur after acute
It is sometimes associated with digitalis toxicity in patients with heart disease.[citation needed]
It is most commonly associated with
Pathophysiology
The P-waves and P–R intervals are variable due to a phenomenon called wandering atrial pacemaker (WAP). The electrical impulse is generated at a different focus within the atria of the heart each time. WAP is positive once the heart generates at least three different P-wave formations from the same ECG lead. Then, if the heart rate exceeds 100 beats per minute, the phenomenon is called multifocal atrial tachycardia.[citation needed]
Diagnosis
Multifocal atrial tachycardia is characterized by an
Other diagnoses that may present with similar findings on electrocardiogram that should be included in the differential diagnosis include sinus tachycardia with frequent premature atrial contractions (this would have regular PP intervals), atrial flutter with variable AV node conduction (this would have regular PP intervals and flutter waves), atrial fibrillation (this would not have discrete P-wave morphologies), and wandering atrial pacemaker which would have a heart rate less than 100 beats per minute).[7]
Additional workup
If arrhythmia persists despite the treatment of underlying medical conditions it may be worth checking a complete blood count and serum chemistry for signs of infection, anemia, or electrolyte abnormalities such as hypokalemia and hypomagnesemia.[7]
Treatment
Management of multifocal atrial tachycardia consists mainly of the treatment of the underlying cause.
In the presence of underlying pulmonary disease, the first-line agent is a non-dihydropyridine calcium channel blocker such as verapamil or diltiazem. These agents act to suppress atrial rate and decrease conduction through the atrioventricular node, thereby slowing the ventricular rate. Studies have found an average reduction in the ventricular rate of 31 beats per minute and 43% of patients reverted to sinus rhythm. Caution should be used in patients with preexisting heart failure or hypotension due to negative inotropic effects and peripheral vasodilation. Similarly, calcium channel blockers should also be avoided in patients with atrioventricular blocks unless a pacemaker has been implanted.[7]
In select cases of refractory multifocal atrial tachycardia, AV node ablation has been performed. Studies have found an average reduction in the ventricular rate of 56 beats per minute with adequate control of ventricular response in 84% of patients. However, AV node ablation creates a complete heart block and requires the placement of a permanent pacemaker.[7]
Administration of oxygen may play a role in the treatment of some patients.[8]
References
- ^ "Multifocal atrial tachycardia: MedlinePlus Medical Encyclopedia". medlineplus.gov. Retrieved 28 May 2019.
- PMID 11499730.
- ^ "ECG Learning Center – An introduction to clinical electrocardiography". Library.med.utah.edu. Retrieved 2023-06-16.
- ^ PMID 9440591.[permanent dead link]
- PMID 2188131.
- PMID 2189301.
- ^ PMID 29083603. Retrieved 18 August 2020. Text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License.
- ISBN 978-1-934465-03-5. Retrieved 11 November 2010.