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Right ventricular volume unloading evaluated by tangential magnetocardiography.
The Japanese Journal of Thoracic and Cardiovascular Surgery : Official Publication of the Japanese Association for Thoracic Surgery = Nihon Kyobu Geka Gakkai Zasshi
|March 14, 2000
Summary
Tangential magnetocardiography effectively quantifies acute right ventricular volume unloading. This method shows significant shortening of right ventricular depolarization time and reduced amplitude in patients with atrial septal defects post-surgery.
Area of Science:
- Cardiology
- Biophysics
- Medical Imaging
Background:
- Evaluating right ventricular (RV) volume overload with a right bundle branch block (RBBB) using electrocardiography (ECG) is challenging.
- Magnetocardiography (MCG) offers a potential alternative for assessing RV function.
Purpose of the Study:
- To differentiate acute RV volume unloading using tangential magnetocardiography.
- To establish MCG as a tool for assessing RV changes in patients with atrial septal defects (ASDs).
Main Methods:
- Simultaneous measurement of tangential MCG and ECG in nine patients with secundum ASD.
- MCG recordings were taken pre- and post-surgical closure using a 32-channel SQUID system in a magnetically shielded room.
Main Results:
- Significant decrease in QRS duration on ECG post-surgery (p < 0.05).
- RV depolarization time shortened from 40.3 ± 6.1 ms to 25.3 ± 7.4 ms (p < 0.0005) via MCG.
- Maximum peak amplitude during RV depolarization decreased from 17.9 ± 4.8 pT to 11.1 ± 4.9 pT (p < 0.01).
Conclusions:
- Acute RV volume unloading is quantitatively indicated by shortened RV depolarization time on tangential MCG.
- A reduction in the amplitude of current vectors during RV depolarization on tangential MCG also signifies unloading.
- Tangential MCG provides a sensitive method for assessing acute RV volume changes, particularly in the context of RBBB and ASDs.