Paradoxical precordial motion and wasted left ventricular work: The concept of cardiac dyssynergy

Abstract

An attempt has been made to determine the wasted cardiac work involved in paradoxical outward motions of the precordium. The upward displacement during systole of a known weight placed on the apical area has been measured in (a) persons with normal hearts, (b) patients with ischemic heart disease, and (c) patients with disorders that place an increased load on the left ventricle. Reasons for the opinion that the values obtained for wasted left ventricular work are falsely low have been cited. The procedure did not cause consistent changes in useful cardiac work, which was serially measured in a few subjects with and without the weights on the chest. In the normal control subjects, the levels for wasted work varied between 0.1 and 5.3 gram-meters per beat, and the median was about 2.5 per cent of the normal useful (pressure × flow) work of the left ventricle. The data for patients who, in the absence of a precordial weight, had normal tracings of chest-wall motion (kinetocardiograms) were usually within the normal range or only slightly above it. The patients who, without added weight, displayed paradoxical motion had values for wasted work of 5 to 45 gram-meters. Calculations were also made of the wasted stroke effort, i.e., the integral of the wasted work. The range and median for the subjects with normal hearts were .07 to .37 and .23 gram-meter seconds, respectively. Again, some of the patients were within the normal range, but those with pronounced systolic outward motion had values that were markedly elevated, and up to more than 30 times the normal median. Cardiac catheterization was performed in 9 of the 13 patients who had lesions that caused left ventricular overloading. In 6 of these subjects the wasted stroke work exceeded 9 per cent of the useful work (mean aortic pressure × measured stroke volume), and in 3 the wasted work was more than 24 per cent of the useful work of the same subject. The highest value found was 44 per cent of the normal value of 100 gram-meters per beat and 31 per cent of the patient's left ventricular useful stroke work. Calculations from the data suggest that in some patients with severe heart failure the work wasted in paradoxical systolic movements may equal the useful work. In patients at rest the cardiac inefficiency, as judged by wasted work, appeared to parallel the clinical state more closely than did the cardiac performance, as judged by useful work. It is concluded that in some patients the work wasted in causing paradoxical systolic motion is sufficient to cause pronounced impairment of myocardial efficiency. The term ventricular dyssynergy is applied to this condition, in which a portion of the energy generated by some of the fibers is diverted to stretching others. Some possible implications of this concept are discussed. Chief among them is the realization that, although knowledge of the performance (pressure and flow) of a given heart is very helpful, additional information concerning efficiency is essential for complete evaluation of its functional state.