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Electrical alternans, a pattern in heartbeats, strongly suggests cardiac tamponade in patients with pericardial effusion. This occurs as the heart rhythmically moves within the fluid-filled pericardial sac.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Diagnostics
Background:
- Pericardial effusion, the accumulation of fluid around the heart, can lead to life-threatening cardiac tamponade.
- Cardiac tamponade impairs the heart's ability to pump blood effectively.
- Identifying reliable indicators of cardiac tamponade is crucial for timely intervention.
Purpose of the Study:
- To investigate the diagnostic value of electrical alternans in patients with pericardial effusion.
- To characterize different types of electrical alternans observed in this context.
- To elucidate the mechanism of electrical alternans in cardiac tamponade.
Main Methods:
- Clinical observation of nine patients with pericardial effusion.
- Electrocardiographic (ECG) monitoring to detect electrical alternans.
- Correlation of ECG findings with clinical diagnosis and radiological evidence of effusion.
Main Results:
- Four out of nine patients developed cardiac tamponade.
- Electrical alternans was present in all four patients with cardiac tamponade (total in three, ventricular in one).
- New types of electrical alternans (2:1, 3:1, varying) were identified, alongside the classic 1:1 pattern.
Conclusions:
- Electrical alternans is a strong indicator of impending or established cardiac tamponade in pericardial effusion.
- The mechanism involves the heart oscillating within the fluid-filled pericardial sac at frequencies related to the heart rate.
- Electrical alternans can occur even at lower heart rates (<100 bpm).
Abstract:
Of nine patients with pericardial effusion due to various causes, four developed cardiac tamponade. Electrical alternans was present in all four, being total in three and ventricular in one. The alternans corresponded very well with the clinical diagnosis of cardiac tamponade and the radiological signs of a large pericardial effusion. In two patients alternans was present even with heart rates below 100 per minute. Apart from the exact (1 : 1) type of electrical alternans, three new types are described, a 2 : 1, 3 : 1, and a varying type. It is concluded that (a) electrical alternans associated with pericardial effusion is strongly suggestive of impending or established cardiac tamponade, and (b) electrical alternans is produced when the heart is oscillating within the pericardial sac distended by fluid with a frequency equal to one-half (exact alternans), one-third (2 : 1 alternans), and one-quarter (3 : 1 alternans) of the heart rate. The aetiology and mechanism of electrical alternans are discussed.