Introduction: Congestive heart failure (CHF) patients suffer from functional aerobic impairment. It is accepted that exercise improves their quality of life; yet the effect on the failing myocardium is unclear. We evaluated the utility of novel speckle tracking echocardiography (STE) for determining the effect of exercise on cardiac structure and function in CHF.
Methods: 18 rats underwent left anterior descending artery ligation. At baseline, pre-training and upon exercise training completion the rats underwent exercise capacity test (VO2 max),apical (AP) and papillary muscle (PM) parasternal short axis echocardiography. Fractional shortening (FS) and ejection fraction (EF) were derived. These scans were post-processed by speckle tracking echocardiography (STE). STE assesses LV global and segmental circumferential strain (SC). Following the establishment of CHF, the animals were assigned to an eight-weeks training program of sedentary (SED), moderate aerobic training (MAT) or high intensity training (HIT) (n=6 each).
Results: Five weeks after surgery, rats` exercise capacity was impaired, their LV was dilated, and EF and FS attenuated. Their global SCs increased significantly (AP: -22±5% to -11±4%, PM: -21±4% to -10±4 %). Upon completion of the exercise program, no improvement in VO2 max, structural or functional parameters was noted in the SED and MAT groups, while in the HIT group those parameters improved. The global SC of SED group deteriorated, whereas of the MAT and HIT groups decreased towards baseline (AP: -9±4%, -13±7%, -17±7%* and at the PM level: -8±2%, -13±5% and -16±4%*, respectively). A dose response between exercise intensity and segmental SC data was also noted.
Conclusions: Exercise training induces improvement in cardiac function in an animal model of CHF. However, only using advanced tools such as the STE these effects can be detected. Further, there is a possible correlation between the exercise intensity and its effect on the cardiac function.
* Pvs. SED
