Limitations of the cardiokymograph for assessing left ventricular wall motion

In order to evaluate the reliability and reproducibility of the CKG we studied four groups of patients. In 27 patients with a prior myocardial infarction the CKG recordings were compared to simultaneous wall motion videotracking. Identical wall motion was recorded in 75% of left ventricular sites and most of the discordant sites were false abnormal posterior wall motion recorded by the CKG. The second group consisted of 21 normal subjects studied by CKG only and 35% displayed anterior dyskinesis during expiration. The third group consisted of nine stable patients who were studied on two separate days by CKG and identical wall motion was recorded in only 55% of the sites on the two recordings. The final group consisted of seven patients with mitral regurgitation and all had late systolic outward movement posteriorly. Systolic wall motion was normal postoperatively in the three patients who underwent valve replacement. We conclude that: (1) the usefulness of the CKG is limited by the frequent recording of false wall motion abnormalities in normal subjects, (2) false anterior wall motion abnormalities can be reduced by recording during inspiration, (3) false posterior wall motion abnormalities may be due to systolic left atrial expansion, and (4) cardioxymography recordings are often not reproducible.