Myocardial Contraction during the Diastolic Isovolumetric Period: Analysis of Longitudinal Strain by Means of Speckle Tracking Echocardiography

Abstract

Background: According to the ventricular myocardial band model, the diastolic isovolumetric period is a contraction phenomenon. Our objective was to employ speckle-tracking echocardiography (STE) to analyze myocardial deformation of the left ventricle (LV) and to confirm if it supports the myocardial band model. Methods: This was a prospective observational study in which 90 healthy volunteers were recruited. We evaluated different types of postsystolic shortening (PSS) from an LV longitudinal strain study. Duration of latest deformation (LD) was calculated as the time from the start of the QRS complex of the ECG to the latest longitudinal deformation peak in the 18 segments of the LV. Results: The mean age of our subjects was 50.3 ± 11.1 years. PSS was observed in 48.4% of the 1620 LV segments studied (19.8%, 13.5%, and 15.1% in the basal, medial, and apical regions, respectively). PSS was more frequent in the basal, medial septal, and apical anteroseptal segments (>50%). LD peaked in the interventricular septum and in the basal segments of the LV. Conclusions: The pattern of PSS and LD revealed by STE suggests there is contraction in the postsystolic phase of the cardiac cycle. The anatomical location of the segments in which this contraction is most frequently observed corresponds to the main path of the ascending component of the myocardial band. This contraction can be attributed to the protodiastolic untwisting of the LV.

Cardiac Helical Function

“…The difference in the duration of mean systolic strain between the systolic and postsystolic phase in the echocardiographic work of Mora Llabata et al is 88 ± 7.1 ms, a value analogous to those found in our research in relation to the duration of the ascending segment activation in the suction phase. (23,24) We have measured the left intraventricular pressure curve in patients who underwent cardiac resynchronization therapy in order to show the improvement at the level of the suction mechanism in the diastolic isovolumic phase.…”

“…To calculate the twist, the echocardiograph algorithm performs an algebraic sum (it adds the positive value of apical rotation to the negative one of basal rotation) In our experience, the value in normal subjects is around + 19 ± 9 º, always with predominant apical rotation 5) Post-systolic longitudinal strain, which indicates the activity during relaxation, is basically produced in septal segments and in the anterior basal region corresponding to the anatomical location of the ascending segment. (23) The twist of an elastic and non-compressible material, such as the myocardium, involves a longitudinal shortening. In the case of the LV, the base and the apex rotate in opposite directions around the longitudinal axis of the LV at the same time as the base moves closer to the apex, which occurs due to the helical arrangement of the myocardial bers.…”

Echocardiography in the Assessment of Postsystolic Shortening of the Left Ventricle Myocardium of the Heart

“…В исследовании V. Mora и соавт. [6] ПСУ у здоровых лиц определялось в 48,4% сегментов, а в исследовании J. Voigt и соавт. [2], в котором ПСУ констатировали при ПСИ >20%, в 31% сегментов.…”

“…Как уже отмечалось ранее, ПСУ может регистрироваться у здоровых лиц, поэтому некоторые авторы предлагают оценивать ПСУ как патологический при ПСИ >20 % или значениях постсис толического времени >90 мс [2]. Другие же авторы указывают на возможные более жесткие критерии патологического ПСУ [5,6].…”

La teoría de la banda miocárdica. Nuevos descubrimientos que apoyan el complejo mecanismo de torsión miocárdica

“…Fibras externas oblícuas Figura 14. Disposición de las fibras (ventrículo izquierdo) (10) Con las técnicas de speckle tracking se confirma la presencia de una leve deformación postsistólica normal en el ventrículo izquierdo, su distribución y la relación temporal con la contracción activa en el periodo isovolumétrico diastólico del ventrículo izquierdo, como mecanismo íntimo y responsable de la succión, concluyendo que los segmentos con mayor porcentaje de registro de deformación postsistólica se corresponden anatómicamente con la porción ascendente de la lazada apical de la banda miocárdica (11) .…”