ABSTRACT
OBJECTIVE: For chronic heart failure (CHF), more emphasis has been placed on evaluation of systolic as opposed to diastolic function. Within the study of diastology, measurements of left ventricular (LV) longitudinal myocardial relaxation have the most validation. Anterior wall radial myocardial tissue relaxation velocities along with mitral valve inflow (MVI) patterns are applicable diastolic parameters in the differentiation between moderate and severe disease in the ischemic rat model of CHF. Myocardial tissue relaxation velocities correlate with traditional measurements of diastolic function (ie, hemodynamics, Tau, and diastolic pressure-volume relationships). METHODS AND RESULTS: Male Sprague-Dawley rats underwent left coronary artery ligation or sham operation. Echocardiography was performed at 3 and 6 weeks after coronary ligation to evaluate LV ejection fraction (EF) and LV diastolic function through MVI patterns (E, A, and E/A) and Doppler imaging of the anterior wall (e' and a'). The rats were categorized into moderate or severe CHF according to their LV EF at 3 weeks postligation. Invasive hemodynamic measurements with solid-state pressure catheters were obtained at the 6-week endpoint. Moderate (N = 20) and severe CHF (N = 22) rats had significantly (P < .05) different EFs, hemodynamics, and diastolic pressure-volume relationships. Early diastolic anterior wall radial relaxation velocities as well as E/e' ratios separated moderate from severe CHF and both diastolic parameters had strong correlations with invasive hemodynamic measurements of diastolic function. CONCLUSION: Radial anterior wall e' and E/e' can be used for serial assessment of diastolic function in rats with moderate and severe CHF.
Subject(s)
Blood Pressure/physiology , Echocardiography/methods , Heart Failure/diagnostic imaging , Recovery of Function/physiology , Severity of Illness Index , Animals , Chronic Disease , Heart Failure/physiopathology , Male , Rats , Rats, Sprague-DawleyABSTRACT
OBJECTIVE: The objective of this study was to define the clinical relevance of in vivo electrophysiologic (EP) studies in a rat model of chronic ischemic heart failure (CHF). METHODS: Electrical activation sequences, voltage amplitudes, and monophasic action potentials (MAPs) were recorded from adult male Sprague-Dawley rats six weeks after left coronary artery ligation. Programmed electrical stimulation (PES) sequences were developed to induce sustained ventricular tachycardia (VT). The inducibility of sustained VT was defined by PES and the recorded tissue MAPs. RESULTS: Rats in CHF were defined ( 0.05) by elevated left ventricular (LV) end-diastolic pressure (5 ± 1 versus 18 ± 2 mmHg), decreased LV + d P/dt (7496 ± 225 versus 5502 [Formula: see text] s), LV - dP/dt (7723 ± 208 versus 3819 [Formula: see text]), LV ejection fraction (79 ± 3 versus [Formula: see text]), peak developed pressure (176 ± 4 versus 145 ± 9 mmHg), and prolonged time constant of LV relaxation Tau (18 ± 1 versus 29 ± 2 ms). The EP data showed decreased ( 0.05) electrogram amplitude in border and infarct zones (Healthy zone (H): 8.7 ± 2.1 mV, Border zone (B): 5.3 ± 1.6 mV, and Infarct zone (I): 2.3 ± 1.2 mV), decreased MAP amplitude in the border zone (H: [Formula: see text] 1.0 mV, B: 9.7 ± 0.5 mV), and increased repolarization heterogeneity in the border zone (H: 8.1 ± 1.5 ms, B: 20.2 ± 3.1 ms). With PES we induced sustained VT (>15 consecutive PVCs) in rats with CHF (10/14) versus Sham (0/8). CONCLUSIONS: These EP studies establish a clinically relevant protocol for studying genesis of VT in CHF. SIGNIFICANCE: The in vivo rat model of CHF combined with EP analysis could be used to determine the arrhythmogenic potential of new treatments for CHF.
