Norm of Vectorcardiogram
Requires interpretation by an expert. P, QRS, and T loops are evaluated for direction, magnitude, and inscription.
Usage of Vectorcardiogram
Identification and classification of myocardial infarction; evaluation of risk for myocardial infarction progression to complete heart block; aids in diagnosis of ventricular preexcitation and localization of ventricular bypass tracts.
Description of Vectorcardiogram
A vectorcardiogram (VCG) is a spatial representation of the sequence of changes in the heart's electrical activity measured three-dimensionally along the x-(horizontal, transverse, left-to-right) axis, y-(vertical, head-to-foot) axis, and z-(sagittal, anteroposterior) axis. A vector represents the heart's electrical potential with respect to specific direction and magnitude. The vectorcardiograph simultaneously records two lead axes at a time to represent the frontal plane vector (x, y), the horizontal plane vector (x, z), and the sagittal plane vector (y, z) and provides a screen display or graphic recording of P, QRS, and T vector loops that move in the same direction as the heart's electrical activity. The literature demonstrates controversy regarding the ability of VCG to better detect and classify myocardial infarction than ECG, though it is advantageous to patients with AMI treated with thrombolytic therapy (Gill et al, 2002). This expensive procedure is infrequently performed in clinical settings but is used as a teaching tool.
Professional Considerations of Vectorcardiogram
Consent form NOT required.
- Obtain a vectorcardiogram machine, electrodes, and conductive gel.
- The client is positioned supine.
- Conductive electrodes are applied according to institutional protocol (usually to the anterior and posterior upper torso, left lower extremity, and the forehead or nape of the neck).
- The machine is activated, and the vectorcardiogram is completed in about 10 minutes.
- Remove the electrodes. Cleanse the skin of conductive gel.
Client and Family Teaching
- It is important to relax, breathe normally, and lie very still throughout the recording.
Factors That Affect Results
- The client's sex, age, medications, and clinical picture must be considered when one is interpreting the results.
- One study recommends that respiratory status be identical for serial vectorcardiograms to diminish the effects of respiration and ventilation on the results (Leanderson et al, 2003).
- The vectorcardiogram is most useful when evaluated in combination with an electrocardiogram.