title: Strain and strain rate by speckle-tracking echocardiography correlate with pressure-volume loop-derived contractility indices in a rat model of athlete's heart.
abstract: Contractile function is considered to be precisely measurable only by invasive hemodynamics. We aimed to correlate strain values measured by speckle-tracking echocardiography (STE) with sensitive contractility parameters of pressure-volume (P-V) analysis in a rat model of exercise-induced left ventricular (LV) hypertrophy. LV hypertrophy was induced in rats by swim training and was compared with untrained controls. Echocardiography was performed using a 13-MHz linear transducer to obtain LV long- and short-axis recordings for STE analysis (GE EchoPAC). Global longitudinal (GLS) and circumferential strain (GCS) and longitudinal (LSr) and circumferential systolic strain rate (CSr) were measured. LV P-V analysis was performed using a pressure-conductance microcatheter, and load-independent contractility indices [slope of the end-systolic P-V relationship (ESPVR), preload recruitable stroke work (PRSW), and maximal dP/dt-end-diastolic volume relationship (dP/dtmax-EDV)] were calculated. Trained rats had increased LV mass index (trained vs. control; 2.76 ± 0.07 vs. 2.14 ± 0.05 g/kg, P < 0.001). P-V loop-derived contractility parameters were significantly improved in the trained group (ESPVR: 3.58 ± 0.22 vs. 2.51 ± 0.11 mmHg/μl; PRSW: 131 ± 4 vs. 104 ± 2 mmHg, P < 0.01). Strain and strain rate parameters were also supernormal in trained rats (GLS: -18.8 ± 0.3 vs. -15.8 ± 0.4%; LSr: -5.0 ± 0.2 vs. -4.1 ± 0.1 Hz; GCS: -18.9 ± 0.8 vs. -14.9 ± 0.6%; CSr: -4.9 ± 0.2 vs. -3.8 ± 0.2 Hz, P < 0.01). ESPVR correlated with GLS (r = -0.71) and LSr (r = -0.53) and robustly with GCS (r = -0.83) and CSr (r = -0.75, all P < 0.05). PRSW was strongly related to GLS (r = -0.64) and LSr (r = -0.71, both P < 0.01). STE can be a feasible and useful method for animal experiments. In our rat model, strain and strain rate parameters closely reflected the improvement in intrinsic contractile function induced by exercise training.
authors.affiliation: Heart and Vascular Center, Semmelweis University, Budapest, Hungary.
authors.forename: Attila
authors.initials: A
authors.lastname: Kovács
authors.affiliation: Heart and Vascular Center, Semmelweis University, Budapest, Hungary.
authors.forename: Attila
authors.initials: A
authors.lastname: Oláh
authors.affiliation: Heart and Vascular Center, Semmelweis University, Budapest, Hungary.
authors.forename: Árpád
authors.initials: Á
authors.lastname: Lux
authors.affiliation: Heart and Vascular Center, Semmelweis University, Budapest, Hungary.
authors.forename: Csaba
authors.initials: C
authors.lastname: Mátyás
authors.affiliation: Heart and Vascular Center, Semmelweis University, Budapest, Hungary.
authors.forename: Balázs Tamás
authors.initials: BT
authors.lastname: Németh
authors.affiliation: Heart and Vascular Center, Semmelweis University, Budapest, Hungary.
authors.forename: Dalma
authors.initials: D
authors.lastname: Kellermayer
authors.affiliation: Heart and Vascular Center, Semmelweis University, Budapest, Hungary.
authors.forename: Mihály
authors.initials: M
authors.lastname: Ruppert
authors.affiliation: Heart and Vascular Center, Semmelweis University, Budapest, Hungary.
authors.forename: Marianna
authors.initials: M
authors.lastname: Török
authors.affiliation: Heart and Vascular Center, Semmelweis University, Budapest, Hungary.
authors.forename: Lilla
authors.initials: L
authors.lastname: Szabó
authors.affiliation: Heart and Vascular Center, Semmelweis University, Budapest, Hungary.
authors.forename: Anna
authors.initials: A
authors.lastname: Meltzer
authors.affiliation: Heart and Vascular Center, Semmelweis University, Budapest, Hungary.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Assabiny
authors.affiliation: Heart and Vascular Center, Semmelweis University, Budapest, Hungary.
authors.forename: Ede
authors.initials: E
authors.lastname: Birtalan
authors.affiliation: Heart and Vascular Center, Semmelweis University, Budapest, Hungary.
authors.forename: Béla
authors.initials: B
authors.lastname: Merkely
authors.affiliation: Heart and Vascular Center, Semmelweis University, Budapest, Hungary radovitstamas@yahoo.com.
authors.forename: Tamás
authors.initials: T
authors.lastname: Radovits
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001696:Biomechanical Phenomena; D006328:Cardiac Catheterization; D059267:Cardiomegaly, Exercise-Induced; D004452:Echocardiography / Q000379:methods*; D006352:Heart Ventricles / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D017379:Hypertrophy, Left Ventricular / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology; D008297:Male; D023421:Models, Animal; D009200:Myocardial Contraction; D005082:Physical Exertion; D011237:Predictive Value of Tests; D017208:Rats, Wistar; D013314:Stress, Mechanical; D013550:Swimming; D013997:Time Factors; D016277:Ventricular Function, Left; D017725:Ventricular Pressure
keywords: athlete's heart; contractility; pressure-volume analysis; speckle-tracking echocardiography; strain