Left Ventricular Twist Mechanics in a Canine Model of Reversible Congestive Heart Failure: A Pilot Study
Section snippets
Animal Preparation
The study protocol was approved by the animal care and use committees of the Institute of Biosciences and Technology, Texas A&M University, and of the Methodist Hospital Research Institute. The study adhered to the Public guidelines for the care and use of laboratory animals. Thirteen adult male mongrel dogs were studied (weight, 35-40 kg). In each procedure, the dog was sedated by the intramuscular injection of xylazine (0.75-1.5 mg/kg) and atropine (0.02-0.06 mg/kg). Anesthesia was induced by
Animals
Complete data sets were available at all 3 stages of the study from 6 dogs and were analyzed and compared using repeated-measures analysis of variance. Data from the other dogs were lost during follow up because of premature death, experimental complications, implanted pacing system failure, or poor image quality.
Changes in Echocardiographic and Hemodynamic Variables
As summarized in Table 1, LV end-diastolic volume and LV end-systolic volume increased, while EF decreased significantly in all dogs during CHF. All of these variables returned to
Discussion
We performed a pilot study to investigate LV dynamics in a canine model of pacing-induced heart failure. We demonstrated that LV twist, torsion, and untwisting rate were impaired during CHF and improved upon recovery from heart failure.
The quantification of LV function is usually cumbersome. The most frequent measure of LV systolic function is EF. The measurement of EF as recommended by the American Society of Echocardiography requires accurate manual tracing of the LV endocardium, which can be
Conclusions
LV twist dynamics, as assessed by echocardiographic speckle tracking, reflect pacing-induced CHF and its reversal. Our preliminary findings suggest that LV twist or torsion may be used to monitor LV function during treatment of heart failure.
Acknowledgment
We thank April Gilbert, BS, and Daryl Schulz, RTR, for their technical assistance.
References (16)
Basic science review: the helix and the heart
J Thorac Cardiovasc Surg
(2002)- et al.
Alterations in left ventricular torsion in tachycardia-induced dilated cardiomyopathy
J Thorac Cardiovasc Surg
(2002) - et al.
Global longitudinal strain: a novel index of left ventricular systolic function
J Am Soc Echocardiogr
(2004) - et al.
Measurement of ventricular torsion by two-dimensional ultrasound speckle tracking imaging
J Am Coll Cardiol
(2005) - et al.
Myofilament remodeling during the progression of heart failure
J Card Fail
(2002) - et al.
Left ventricular systolic torsion and early diastolic filling by echocardiography in normal humans
Am J Cardiol
(1998) - et al.
Alterations in left ventricular twist mechanics with inotropic stimulation and volume loading in human subjects
Circulation
(1994) - et al.
Dissociation between left ventricular untwisting and fillingAccentuation by catecholamines
Circulation
(1992)
Cited by (0)
This study was supported in part by research grant R01HL068768 from the National Institutes of Health, Bethesda, MD, and a research grant from the Cardiac Rhythm Management Division, St. Jude Medical, Sylmar, CA (both to Dr Khoury).