The monitoring myocardial ischemia
Electrocardiography is employed in qualitative (pattern-based) and quantitative formats, for the diagnosis and follow-up of patients. Measuring the amplitude of various parts of the ECG waveform provides data suitable for comparison and statistical analysis. Measurements of the ST segment have been employed in exercise testing and in the CCU for the purposes of monitoring myocardial ischemia. Similar treatment of the QRS complexes can be used for the purposes of diagnosing and monitoring patients who have developed or are recovering from edematous states of various etiologies. 
Daily experience particularly in critical care units reveals the vagaries of obtaining patients’ Ws using sling scales. The calculation of 2QRS12 may be useful in monitoring changes in extent of peripheral edema. Although this also could be time-consuming, it could be probably handled electronically by automated ECG interpretation programs. Another application of the ECG/W correlations could be in setting up changing voltage-dependent ECG criteria for various diagnoses (ie, left ventricular hypertrophy) in patients with extreme fluid overload states. Thus, for patients with AN or CHF, or for those undergoing hemodialysis, the diagnosis of left ventricular hypertrophy should be made with reference to the stage (ie, compensated and uncompensated) of their edematous state.
The reliability of the 2QRS12 in detecting fluid accumulation or loss may improve when ECGs are recorded from fixed chest wall landmarks, ensuring comparable precordial ECG recordings. In our previous studies, we used routine daily ECGs recorded by our technicians, without the above provision. It appears from the present study that for clinical and research applications focusing on the QRS amplitude (and excluding patients with AN), one can employ measurements from the 2-lead ECG and 6-lead ECG instead of the 12-lead ECG. This was highlighted by the data from the three patients treated for CHF, for whom the correlations among the three ECG systems were very strong. However, this might have been a chance finding, since only three patients were studied, and data from hospital admission and discharge were lumped together.
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