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Acute volume overload elevates T-wave alternans magnitude.

Sanjiv M Narayan1, Darrel D Drinan, Robert P Lackey

  • 1University of California, San Diego, California 92161, USA. snarayan@ucsd.edu

Journal of Applied Physiology (Bethesda, Md. : 1985)
|December 13, 2006
PubMed
Summary

Acute volume loading significantly increases T-wave alternans (TWA) in healthy canine hearts. This finding suggests that excessive fluid overload may contribute to cardiac arrhythmias, particularly in susceptible patients.

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Area of Science:

  • Cardiology
  • Electrophysiology
  • Cardiac Physiology

Background:

  • T-wave alternans (TWA) is a predictor of sudden cardiac arrest in patients with heart failure.
  • The impact of acute volume loading on TWA in hearts without structural abnormalities is not well understood.
  • Ventricular stretch from volume overload may precipitate arrhythmias.

Purpose of the Study:

  • To investigate whether acute volume loading elevates T-wave alternans (TWA) in dogs with normal heart structure.
  • To determine the relationship between the degree of volume load and TWA magnitude.
  • To assess the effect of induced acute congestive heart failure (CHF) on TWA.

Main Methods:

  • Six mongrel dogs underwent progressive atrial pacing under anesthesia.
  • TWA was measured at baseline, during saline infusion (to induce acute CHF), and during diuresis.
  • Physiological parameters including pulmonary capillary wedge pressure and heart rate variability were monitored.

Main Results:

  • Volume loading significantly increased TWA magnitude (Valt) in all dogs (P < 0.001).
  • Peak TWA magnitude was significantly higher at peak infusion compared to baseline (3.4 vs. 0.5 muV; P = 0.011).
  • Increased volume load showed a linear relationship with TWA magnitude, with each 10 ml/kg increasing Valt by 0.23 muV.

Conclusions:

  • Acute volume overload can elevate TWA even in structurally normal hearts.
  • This effect might clinically contribute to abnormal TWA in patients with significant volume overload.
  • Further research is needed on the interplay between fluid overload, heart disease, and arrhythmia risk.