RESUMEN
AIMS: Early inward motion and thickening/thinning of the ventricular septum associated with left bundle branch block is known as the septal flash (SF). Correction of SF corresponds to response to cardiac resynchronization therapy (CRT). We hypothesized that SF was associated with a specific left ventricular (LV) activation pattern predicting a favourable response to CRT. We sought to characterize the spatio-temporal relationship between electrical and mechanical events by directly comparing non-contact mapping (NCM), acute haemodynamics, and echocardiography. METHODS AND RESULTS: Thirteen patients (63 ± 10 years, 10 men) with severe heart failure (ejection fraction 22.8 ± 5.8%) awaiting CRT underwent echocardiography and NCM pre-implant. Presence and extent of SF defined visually and with M-mode was fused with NCM bull's eye plots of endocardial activation patterns. LV-dP/dt(max) was measured during different pacing modes. Five patients had a large SF, four small SF, and four no SF. Large SF patients had areas of conduction block in non-infarcted regions, whereas those with small or no SF did not. Patients with large SF had greater acute response to LV and biventricular (BIV) pacing vs. those with small/no SF (% increase dP/dt 28 ± 14 vs. 11 ± 19% for LV pacing and 42 ± 28 vs. 22 ± 21% for BIV pacing) (P < 0.05). This translated into a more favourable chronic response to CRT. The lines of conduction block disappeared with LV/BIV pacing while remaining with right ventricle pacing. CONCLUSION: A strong association exists between electrical activation and mechanical deformation of the septum. Correction of both mechanical synchrony and the functional conduction block by CRT may explain the favourable response in patients with SF.
Asunto(s)
Bloqueo de Rama/terapia , Terapia de Resincronización Cardíaca , Técnicas Electrofisiológicas Cardíacas , Insuficiencia Cardíaca/terapia , Tabiques Cardíacos/fisiopatología , Anciano , Bloqueo de Rama/diagnóstico por imagen , Electrocardiografía , Femenino , Insuficiencia Cardíaca/diagnóstico por imagen , Tabiques Cardíacos/diagnóstico por imagen , Ventrículos Cardíacos/diagnóstico por imagen , Ventrículos Cardíacos/fisiopatología , Humanos , Masculino , Persona de Mediana Edad , Índice de Severidad de la Enfermedad , Volumen Sistólico/fisiología , Resultado del Tratamiento , UltrasonografíaRESUMEN
BACKGROUND: Failure rate for left ventricular (LV) lead implantation in cardiac resynchronization therapy (CRT) is up to 12%. The use of segmentation tools, advanced image registration software, and high-fidelity images from computerized tomography (CT) and cardiac magnetic resonance (CMR) of the coronary sinus (CS) can guide LV lead implantation. We evaluated the feasibility of advanced image registration onto live fluoroscopic images to allow successful LV lead placement. METHODS: Twelve patients (11 male, 59 ± 16.8 years) undergoing CRT had three-dimensional (3D) whole-heart imaging (six CT, six CMR). Eight patients had at least one previously failed LV lead implant. Using segmentation software, anatomical models of the cardiac chambers, CS, and its branches were overlaid onto the live fluoroscopy using a prototype version of the Philips EP Navigator software to guide lead implantation. RESULTS: We achieved high-fidelity segmentations of cardiac chambers, coronary vein anatomy, and accurate registration between the 3D anatomical models and the live fluoroscopy in all 12 patients confirmed by balloon occlusion angiography. The CS was cannulated successfully in every patient and in 11, an LV lead was implanted successfully. (One patient had no acceptable lead values due to extensive myocardial scar). CONCLUSION: Using overlaid 3D segmentations of the CS and cardiac chambers, it is feasible to guide CRT implantation in real time by fusing advanced imaging and fluoroscopy. This enabled successful CRT in a group of patients with previously failed implants. This technology has the potential to facilitate CRT and improve implant success.
Asunto(s)
Terapia de Resincronización Cardíaca , Seno Coronario/diagnóstico por imagen , Seno Coronario/patología , Electrodos Implantados , Ventrículos Cardíacos/cirugía , Imagen por Resonancia Cinemagnética/métodos , Tomografía Computarizada por Rayos X/métodos , Anciano , Terapia de Resincronización Cardíaca/métodos , Dispositivos de Terapia de Resincronización Cardíaca , Femenino , Ventrículos Cardíacos/diagnóstico por imagen , Ventrículos Cardíacos/patología , Humanos , Masculino , Implantación de Prótesis/métodos , Cirugía Asistida por ComputadorRESUMEN
PURPOSE: To evaluate a cardiac MR (CMR) examination with slow infusion of a high-relaxivity contrast agent to visualize coronary venous anatomy (CVA) and myocardial scar in heart failure patients awaiting cardiac resynchronization therapy (CRT). MATERIALS AND METHODS: Fourteen patients awaiting CRT (seven ischemic cardiomyopathy (ICM) and seven non-ICM) and two with normal LV function underwent CMR on a 1.5 Tesla (T) MR scanner. Dimeglumine-gadobenate was slowly infused. Bolus arrival in the LV was measured by a dynamic electrocardiogram (ECG) -triggered inversion recovery (IR) scan subsequent to starting an ECG-triggered respiratory-navigated three-dimensional (3D) SSFP MR scan with IR preparation to acquire systolic whole-heart anatomy for vein visualization. Delayed contrast-enhanced MR scan was performed to assess myocardial scar. CVA obtained by CMR was compared with X-ray venography in 11 patients. CVA and scar were segmented and registered for visual inspection. RESULTS: For all subjects, there was excellent visualization of the CVA. All ICM and one non-ICM patient showed scar. There was excellent correlation between veins seen by CMR and venography. CONCLUSION: We have demonstrated that slow infusion protocol of dimeglumine-gadobenate can be used to assess both CVA and myocardial scar in a single MR examination. Furthermore, an image overlay technique has been used to show the relationship of scar to the CVA.