ABSTRACT
AIMS: Contact force (CF) between radiofrequency (RF) ablation catheter and myocardium and ablation index (AI) correlates with RF lesion depth and width in normal-voltage (>1.5 mV) myocardium (NVM). We investigate the impact of CF on RF lesion depth and width in low (<0.5 mV) (LVM) and intermediate-voltage (0.5-1.5 mV) myocardium (IVM) following myocardial infarction. Correlation between RF lesion depth and width evaluated by native contrast magnetic resonance imaging (ncMRI) and gross anatomical evaluation was investigated. METHODS AND RESULTS: Twelve weeks after myocardial infarction, 10 pigs underwent electroanatomical mapping and endocardial RF ablations were deployed in NVM, IVM, and LVM myocardium. In vivo ncMRI was performed before the heart was excised and subjected to gross anatomical evaluation. Ninety (82%) RF lesions were evaluated. Radiofrequency lesion depth and width were smaller in IVM and LVM compared with NVM (P < 0.001). Radiofrequency lesion depth and width correlated with CF, AI, and impedance drop in NVM (CF and AI P < 0.001) and IVM (CF and AI depths P < 0.001; CF and AI widths P < 0.05). Native contrast magnetic resonance imaging evaluated RF lesion depth and width correlated with gross anatomical depth and width (NVM and IVM P < 0.001; LVM P < 0.05). CONCLUSIONS: Radiofrequency lesions deployed by similar duration, power and CF are smaller in IVM and LVM than in NVM. Radiofrequency lesion depth and width correlated with CF, AI, and impedance drop in NVM and IVM but not in LVM. Native contrast magnetic resonance imaging may be useful to assess RF lesion depth and width in NVM, IVM, and LVM.
Subject(s)
Catheter Ablation/methods , Cicatrix/physiopathology , Heart/diagnostic imaging , Myocardial Infarction/physiopathology , Myocardium/pathology , Tachycardia, Ventricular/surgery , Animals , Cardiac Surgical Procedures , Cicatrix/diagnostic imaging , Cicatrix/pathology , Electric Impedance , Electrophysiologic Techniques, Cardiac , Magnetic Resonance Imaging , Myocardial Infarction/diagnostic imaging , Myocardial Infarction/pathology , Recurrence , Sus scrofa , Swine , Tachycardia, Ventricular/physiopathology , Treatment FailureABSTRACT
BACKGROUND: We investigated if soluble guanylate cyclase stimulation either alone or in combination with phosphodiesterase-5 (PDE5) inhibition could prevent pressure overload-induced right ventricular (RV) hypertrophy and failure. METHODS: The soluble guanylate cyclase stimulator BAY 41-2272 (BAY, 10 mg · kg⻹ · d⻹) either alone or in combination (BAY + SIL) with a PDE5 inhibitor sildenafil (SIL, 100 mg · kg⻹ · d⻹) was examined for prevention of RV hypertrophy and failure in Wistar rats (n = 73) operated by pulmonary trunk banding. RESULTS: All treatments failed to inhibit the development of RV hypertrophy and failure. In the BAY and BAY + SIL groups, there was an increased mortality. Mean arterial blood pressure was lowered and cardiac output increased in the BAY + SIL group. Systolic RV pressure was increased in the BAY and BAY + SIL groups possibly because of an inotropic response and/or increased venous return. CONCLUSIONS: Stimulation of soluble guanylate cyclase by BAY 41-2272 alone or in combination with sildenafil failed to prevent the development of RV hypertrophy and failure in rats subjected to pulmonary trunk banding. An increased mortality was observed in animals treated by BAY 41-2272 alone and in combination with sildenafil.