Usefulness and limitations of circumferential fibre shortening velocity in evaluating segmental disorders of left ventricular contraction

In order to study the possibility of using circumferential fibre shortening velocity (VCF) to assess regional left ventricular performance, 2I left ventricular angiograms (single-plane cine) from i9 patients were examined. In 8 patients with normal left ventricle, measurements of instantaneous and mean VcF in 4 equidistant chords revealed uniform velocities at all chords. In 7 patients with coronary artery disease mean and max VCF were depressed in the areas involved by asynergy; however, when only one wall was affected, velocity measurements of the hemichords provided a better definition of regional performance. VCF at the base (chords A and B) was normal in 2 out of 3 patients with apical asynergy, and augmented in one. Angiotensin produced a reduction in the mean velocity of the anterior wall in apatient with inferior dyskinesis-akinesis; in contrast, nitroglycerin was associated with augmented velocity of the non-akinetic segment in a second patient with inferior akinesis and anteroapical hypokinesis. In contrast to localized asynergy, a diffuse reduction in VCF was observed in a patient with cardiomyopathy. VCF at the base was reduced in a patient with mitral stenosis and in another with mitral valve prolapse, indicating the presence of a localized basal abnornality of left ventricular contraction. The time course of VCp in the patient with mitralprolapse showed an early peak before aortic valve opening, corresponding to a reduction in left ventricular volume (AV) of 22 per cent (in contrast to 3 per cent reduction in the normal left ventricle). Fibre shortening before aortic valve opening was also present in chronic mitral regurgitation (AV= IS%)/ Segmental analysis of normalized velocities provides a quantitative approach to the evaluation of regional left ventricular performance. The sensitivity of VCF to acute changes in loading, however, may limit in some instances the usefulness of this index.