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Effect of hemodialysis on the signal-averaged electrocardiogram
I Girgis1, G Contreras, S Chakko
1Divisions of Cardiology and Nephrology, University of Miami School of Medicine, Miami, FL, USA. epgirgis@home.com
Insights
Signal-averaged electrocardiography (SAECG) identifies late potentials (LPs) predicting ventricular tachycardia. Hemodialysis (HD) improved SAECG parameters in chronic renal failure patients, likely due to fluid removal reducing left ventricular dimensions.
Area of Science:
- Cardiology
- Nephrology
- Medical Diagnostics
Background:
- Late potentials (LPs) on signal-averaged electrocardiography (SAECG) are associated with ventricular tachycardia.
- The impact of hemodialysis (HD) on SAECG findings in chronic renal failure patients remains understudied.
Purpose of the Study:
- To investigate the effect of hemodialysis on SAECG parameters in patients with chronic renal failure.
- To determine if fluid removal during HD influences SAECG findings.
Main Methods:
- SAECG was performed on 28 chronic renal failure patients before and after HD.
- Key SAECG metrics including QRS duration, low-amplitude signal duration (LASd), and RMS40 were measured.
- 12 patients underwent additional SAECG and echocardiography during HD sessions with and without fluid removal.
Main Results:
- The prevalence of LPs decreased significantly after HD.
- Mean LASd decreased, and RMS40 increased post-HD.
- Fluid removal during HD correlated with improved RMS40 and reduced left ventricular end-diastolic dimension.
Conclusions:
- SAECG parameters are frequently abnormal in chronic renal failure patients.
- Hemodialysis appears to improve SAECG findings, suggesting a reduction in arrhythmogenic substrate.
- Fluid removal during HD is a potential mechanism for these SAECG improvements.
Abstract:
The presence of late potentials (LPs) on signal-averaged electrocardiography (SAECG) is predictive of ventricular tachycardia. The effect of hemodialysis (HD) on SAECG has not been well studied. SAECG was evaluated in 28 patients with chronic renal failure immediately before and after HD. In each SAECG, QRS duration, low-amplitude signal duration (LASd), and root-mean-square voltage of the terminal 40 milliseconds of the QRS (RMS40) were measured. To evaluate the effect of fluid removal on SAECG, the last 12 patients were studied during two different HD sessions, one with and one without fluid removal. Two-dimensional echocardiography was performed before and after HD on these 12 patients. At baseline, four patients met the criteria for LPs on SAECG. Only one patient met the criteria for LPs on SAECG after HD. After HD, the mean LASd decreased (28.3 +/- 12.9 to 24.9 +/- 10.1 milliseconds; P = 0.041) and RMS40 increased (63.0 +/- 56.9 to 79.0 +/- 59.2 microV; P = 0. 006). Among the 12 patients who underwent HD with and without fluid removal, left ventricular end-diastolic dimension decreased with (5. 4 +/- 0.6 to 5.1 +/- 0.6 cm; P = 0.024) but not without fluid removal (5.2 +/- 0.3 to 5.1 +/- 0.4 cm; P = not significant [NS]). RMS40 improved with (43.8 +/- 23.1 to 53.2 +/- 22.6 microV; P = 0. 03) but not without fluid removal (51.0 +/- 26.5 to 51.5 +/- 24.2 microV; P = NS). A significant negative correlation was found between change in body weight and change in RMS40 parameter (r = 0. 456; P = 0.0381). SAECG parameters are abnormal in a significant proportion of patients with chronic renal failure and improve with HD despite electrolyte and other proarrhythmic changes. Decreased left ventricular dimension because of fluid removal during HD is one possible explanation for this improvement.