Left ventricular twist mechanics in the context of normal physiology and cardiovascular disease: a review of studies using speckle tracking echocardiography

The Year in Perioperative Echocardiography: Selected Highlights from 2018

This article is the third of an annual series reviewing the research highlights of the year pertaining to the subspecialty of perioperative echocardiography for the Journal of Cardiothoracic and Vascular Anesthesia. The authors thank the editor-in-chief, Dr. Kaplan, and the editorial board for the opportunity to continue this series. In most cases, these will be research articles targeted at the perioperative echocardiography diagnosis and treatment of patients after cardiothoracic surgery; but in some cases, these articles will target the use of perioperative echocardiography in general.

Normal values of left ventricular rotational parameters in healthy adults-Insights from the three-dimensional speckle tracking echocardiographic MAGYAR-Healthy Study

INTRODUCTION

Left ventricular (LV) rotation and twist are essential parts of LV function. Three-dimensional speckle tracking echocardiography (3DSTE) is a relatively new method and is useful for the quantification of LV wall deformation and rotational parameters. The aim of the present study was to examine LV rotation and twist differences between different age-groups and genders in a healthy population.

METHODS

The present study is comprised of 297 healthy adults; 120 adults have been excluded due to inferior image quality. The population was further divided into 4 subgroups based on age decades.

RESULTS

Only the LV twist of all patients (13.5 ± 3.7 degree vs 15.6 ± 4.9 degree, P = 0.02) and the LV twist of females (13.0 ± 3.6 degree vs 15.5 ± 5.6 degree, P = 0.03) differed significantly between the age-group of 18-29 years and 50+ years. LV basal and apical rotation were not significantly different between the age-groups; however, they tendentiously increased with aging. No significant differences could be demonstrated regarding LV rotational and twist parameters between genders in any group. A phenomenon called LV rigid body rotation (LV-RBR)-where the base and apex of the LV rotate in the same direction-was present in 10 cases.

CONCLUSIONS

Three-dimensional speckle tracking echocardiography seems to be a reasonably viable tool for the quantification of LV rotation and twist. Both LV basal and apical rotation and LV twist increase with aging, regardless of gender. LV-RBR is also present in the normal population.

Left ventricular rotation and torsion in neonates and infants younger than three months with symptomatic ventricular septal defect: Acute effects from open heart surgery

PURPOSE

We evaluated ventricular rotation, torsion, and strain changes in infants using preoperative and postoperative M-mode echocardiography after early surgery for symptomatic ventricular septal defects (VSD).

METHODS

Thirty-five patients with VSD underwent vector velocity imaging echocardiography before and after open heart surgery. Their rotational variables were compared with 18 controls.

RESULTS

All the patients (19 boys and 16 girls; median age: 44.4 days; range: 13-84 days) showed normal septal motion preoperatively; however, septal motion changed into flat septum or paradoxical septal motion after surgery. Left ventricular end-diastolic internal dimension and fractional shortening significantly decreased after surgery (P = .001 and P = .000). Patients showed significant postoperative reduction of peak systolic apical rotation and maximal torsion (P = .010 and P = .000). Peak systolic basal rotation decreased after surgery but it was not significantly (P = .106). No significant differences were found in longitudinal and circumferential systolic strains between patients and controls.

CONCLUSION

Abnormal motion of the ventricular septum was confirmed by postoperative M-mode echocardiography. Decreased rotation/torsion variables may reflect postoperative changes of ventricular loading conditions. Because systolic strain was preserved, postoperative echocardiographic results should not be interpreted as abnormal or decreased ventricular function.

Acute Modifications of Left Ventricular Torsional Mechanics Induced by Cardiac Resynchronization Therapy Affect Short-Term Reverse Remodeling

BACKGROUND

Left ventricular (LV) torsion is an important aspect of cardiac mechanics and is altered in heart failure patients. Cardiac resynchronization therapy (CRT) has a positive effect on LV function, but the exact mechanisms through which it works are not completely depicted. Our aim was to investigate (1) the acute CRT effect on LV torsional mechanics in heart failure patients using 3D speckle tracking echocardiography (3DSTE) and (2) its effect on short-term LV remodeling.

METHODS AND RESULTS

We considered 48 patients (age 72±11 years, 35 men) who received CRT. They underwent 3DSTE during CRT-on (biventricular stimulation) vs. CRT-off (intrinsic conduction/right atrial/ventricular stimulation alone), in a random fashion. Patients were classified as CRT responders based on LV systolic volume reduction ≥15% at 6 months (final population: 31 responders, 17 non-responders). Acute CRT positively affected responders in terms of LV torsion (from 0.32±0.06°/cm CRT-off to 0.41±0.06°/cm CRT-on), but adversely affected non-responders (from 0.54±0.08°/cm CRT-off to 0.28±0.08°/cm CRT-on, interaction P=0.02). A similar trend was confirmed for apical (interaction P<0.04), but not for basal torsion (interaction P=0.351).

CONCLUSIONS

CRT has a positive role in acute recovery of LV torsion (particularly in its apical component) in responders, likely modulating the improvement in LV remodeling at early follow-up.

The Memory of the Heart

The embryological development of the heart is one of the most fascinating phenomena in nature and so is its final structure and function. The various ontogenetic passages form the evolutive basis of the final configuration of the heart. Each key step can be recognized in the final features, as the heart maintains a kind of “memory” of these passages. We can identify the major lines of development of the heart and trace these lines up to the mature organ. The aim of this review is to identify these key parameters of cardiac structure and function as essential elements of the heart’s proper functioning and bases for its treatment. We aim to track key steps of heart development to identify what it “remembers” and maintains in its final form as positively selected. A new vision based on the whole acquired knowledge must guide an in-depth scientific approach in future papers and guidelines on the topic and a complete, farsighted therapeutic conduct able to ensure the physiological correction of cardiac pathologies. The application of this modern, functional vision of the heart could improve the clinical treatment of heart disease, filling the gaps still present.

Comprehensive assessment of left ventricular myocardial function by two-dimensional speckle-tracking echocardiography

Background

Left ventricular ejection fraction (LVEF) results from the combined action of longitudinal and circumferential contraction, radial thickening, and basal and apical rotation. The study of these parameters together may lead to an accurate assessment of the cardiac function.

Methods

Ninety healthy volunteers, categorized by gender and age (≤ 55 and >  55 years), were evaluated using two-dimensional speckle tracking echocardiography. Transversal views of the left ventricle (LV) were obtained to calculate circumferential strain and left ventricular twist, while three apical views were obtained to determine longitudinal strain (LS) and mitral annular plane systolic excursion (MAPSE). We established the integral myocardial function of the LV according to: 1. The Combined Deformation Parameter (CDP), which includes Deformation Product (DP) - Twist x LS (° x %) - and Deformation Index (DefI) -Twist / LS (° / %)-; and 2. the Torsion Index (TorI): Twist / MAPSE (° / cm).

Results

The mean age of our patients was 50.3 ± 11.1 years. CDP did not vary with gender or age. The average DP was − 432 ± 172 ° x %, and the average DefI was − 0.96 ± 0.36 ° / %. DP provides information about myocardial function (normal, pseudonormal, depressed), and the DefI quotient indicates which component (s) is/are affected in cases of abnormality. TorI was higher in volunteers over 55 years (16.5 ± 15.2 vs 13.1 ± 5.0 °/cm, p = 0.003), but did not vary with gender.

Conclusions

The proposed parameters integrate values of twisting and longitudinal shortening. They allow a complete physiological assessment of cardiac systolic function, and could be used for the early detection and characterization of its alteration.

Effect of exercise training on left ventricular mechanics after acute myocardial infarction-an exploratory study

BACKGROUND

Cardiac rehabilitation (CR) exercise training is beneficial after myocardial infarction (MI). Whilst the peripheral adaptations to training are well defined, little is known regarding the effect on left ventricular (LV) remodelling, particularly LV function. Efficient LV ejection and filling is achieved through deformation and rotation of the myocardium in systole and diastole - LV mechanics. The response of LV mechanics to CR exercise training in MI patients is unknown.

METHODS

In this observational exploratory study, 36 (of 40 enrolled) male, MI patients completed either 10-weeks of twice-weekly gym based cardiovascular exercise at 60-80% VO_2peak (n=18), or a non-exercise control period (n=18). Cardiopulmonary exercise testing and speckle tracking echocardiography were performed at baseline and 10 weeks.

RESULTS

Compared to the non-exercise group, VO_2peak improved with CR exercise training (Difference: +4.28 [95% CI: 1.34 to 7.23] ml.kg^-1.min^-1, P=0.01). Neither conventional LV structural or functional indices, nor LV global longitudinal strain, significantly changed in either group. In contrast, LV twist and twist velocity decreased in the exercise group and increased in the non-exercise group (Difference: -3.95° [95% CI: -7.92 to 0.03°], P=0.05 and -19.2°.s^-1 [95% CI: -35.9 to -2.7°.s^-1], P=0.02, respectively).

CONCLUSION

In MI patients who completed CR exercise training, LV twist and twist velocity decreased, whereas these parameters increased in patients who did not exercise. These preliminary data may indicate reverse LV functional remodelling and improved functional reserve. The assessment of LV twist may serve as an indicator of the therapeutic benefit of CR exercise training and should be investigated in larger trials.

Ablative Radiotherapy as a Noninvasive Alternative to Catheter Ablation for Cardiac Arrhythmias

Purpose of Review

Stereotactic radioablation is a commonly utilized technology to noninvasively treat solid tumors with precision and efficacy. Using a robotic arm mounted delivery system, multiple low-dose ionizing radiation beams are delivered from multiple angles, concentrating ablative energy at the target tissue. Recently, this technology has been evaluated for treatment of cardiac arrhythmias. This review will present the basic underlying principles, proof-of-principle studies, and clinical experience with stereotactic arrhythmia radioablation.

Recent Findings

Most recently, stereotactic radioablation has been used to safely and effectively treat a limited number of patients with malignant arrhythmias, including ventricular tachycardia (VT) and atrial fibrillation (AF). Treatment protocols, outcomes, ongoing studies, and future directions will be discussed.

Summary

Stereotactic radioablation is a well-established technology that has been shown to be a safe and effective therapy for patients with drug-refractory cardiac arrhythmias, including VT and AF. Further clinical evaluation to define safety and efficacy in larger populations of patients is needed.

Left ventricular twist mechanics during incremental cycling and knee extension exercise in healthy men

Purpose

The objective of the present study was to investigate left ventricular (LV) twist mechanics in response to incremental cycling and isometric knee extension exercises.

Methods

Twenty-six healthy male participants (age = 30.42 ± 6.17 years) were used to study peak twist mechanics at rest and during incremental semi-supine cycling at 30 and 60% work rate maximum (W_max) and during short duration (15 s contractions) isometric knee extension at 40 and 75% maximum voluntary contraction (MVC), using two-dimensional speckle tracking echocardiography.

Results

Data presented as mean ± standard deviation or median (interquartile range). LV twist increased from rest to 30% W_max (13.21° ± 4.63° to 20.04° ± 4.76°, p < 0.001) then remained unchanged. LV systolic and diastolic twisting velocities progressively increased with exercise intensity during cycling from rest to 60% W_max (twisting, 88.21° ± 20.51° to 209.05° ± 34.56° s⁻¹, p < 0.0001; untwisting, −93.90 (29.62)° to −267.31 (104.30)° s⁻¹, p < 0.0001). During the knee extension exercise, LV twist remained unchanged with progressive intensity (rest 13.40° ± 4.80° to 75% MVC 16.77° ± 5.54°, p > 0.05), whilst twisting velocity increased (rest 89.15° ± 21.77° s⁻¹ to 75% MVC 124.32° ± 34.89° s⁻¹, p < 0.01). Untwisting velocity remained unchanged from rest [−90.60 (27.19)° s⁻¹] to 40% MVC (p > 0.05) then increased from 40 to 75% MVC [−98.44 (43.54)° s⁻¹ to −138.42 (73.29)° s⁻¹, p < 0.01]. Apical rotations and rotational velocities were greater than basal during all conditions and intensities (all p < 0.01).

Conclusion

Cycling increased LV twist to 30% W_max which then remained unchanged thereafter, whereas twisting velocities showed further increases to greater intensities. A novel finding is that LV twist was unaffected by incremental knee extension, yet systolic and diastolic twisting velocities augmented with isometric exercise.