Structure and function of the ventricular tachycardia isthmus.

Catheter ablation of postinfarction reentrant ventricular tachycardia (VT) has received renewed interest owing to the increased availability of high-resolution electroanatomic mapping systems that can describe the VT circuits in greater detail, and the emergence and need to target noninvasive external beam radioablation. These recent advancements provide optimism for improving the clinical outcome of VT ablation in patients with postinfarction and potentially other scar-related VTs. The combination of analyses gleaned from studies in swine and canine models of postinfarction reentrant VT, and in human studies, suggests the existence of common electroanatomic properties for reentrant VT circuits. Characterizing these properties may be useful for increasing the specificity of substrate mapping techniques and for noninvasive identification to guide ablation. Herein, we describe properties of reentrant VT circuits that may assist in elucidating the mechanisms of onset and maintenance, as well as a means to localize and delineate optimal catheter ablation targets.

Dual phase cone-beam computed tomography in detecting <3 cm hepatocellular carcinomas during transarterial chemoembolization.

OBJECTIVE: The objective of this study was to evaluate the sensitivity of dual phase cone-beam computed tomography (CBCT) in detecting small (<3 cm in diameter) hepatocellular carcinoma (HCC) tumors during transarterial chemoembolization (TACE). MATERIALS AND METHODS: Twenty-two consecutive patients with unresectable small HCCs in whom TACE was performed were retrospectively evaluated. Contrast CT or contrast magnetic resonance imaging (MRI) was performed in all patients within 1 month prior to the procedure. Dual phase CBCT was performed prior to TACE and lipiodol-CBCT was performed after treatment. The sensitivity of dual phase CBCT in detecting small HCCs was compared to hepatic angiography, contrast enhanced CT and MRI. RESULTS: Seventy HCC tumors with sizes of P < 0.001). CONCLUSIONS: Dual phase CBCT is significantly more sensitive than hepatic angiography, contrast enhanced CT, and MRI in detecting smaller than 3 cm HCC tumors and can be a helpful modality in making accurate planning for treatment of HCC.

Cardiac magnetic resonance T1 mapping of left atrial myocardium.

BACKGROUND: Cardiac magnetic resonance (CMR) T1 mapping is an emerging tool for objective quantification of myocardial fibrosis. OBJECTIVES: To (a) establish the feasibility of left atrial (LA) T1 measurements, (b) determine the range of LA T1 values in patients with atrial fibrillation (AF) vs healthy volunteers, and (c) validate T1 mapping vs LA intracardiac electrogram voltage amplitude measures. METHODS: CMR imaging at 1.5 T was performed in 51 consecutive patients before AF ablation and in 16 healthy volunteers. T1 measurements were obtained from the posterior LA myocardium by using the modified Look-Locker inversion-recovery sequence. Given the established association of reduced electrogram amplitude with fibrosis, intracardiac point-by-point bipolar LA voltage measures were recorded for the validation of T1 measurements. RESULTS: The median LA T1 relaxation time was shorter in patients with AF (387 [interquartile range 364-428] ms) compared to healthy volunteers (459 [interquartile range 418-532] ms; P < .001) and was shorter in patients with AF with prior ablation compared to patients without prior ablation (P = .035). In a generalized estimating equations model, adjusting for data clusters per participant, age, rhythm during CMR, prior ablation, AF type, hypertension, and diabetes, each 100-ms increase in T1 relaxation time was associated with 0.1 mV increase in intracardiac bipolar LA voltage (P = .025). CONCLUSIONS: Measurement of the LA myocardium T1 relaxation time is feasible and strongly associated with invasive voltage measures. This methodology may improve the quantification of fibrotic changes in thin-walled myocardial tissues.

Patent foramen ovale associated with the unusual presentation of unilateral paramedian thalamic perforating artery infarction after embolic occlusion of 'artery of Percheron': case report and review of the literature.

'Artery of Percheron' is a rare variation in blood supply in which a solitary arterial trunk arises from one of the proximal segments of the posterior cerebral arteries and supplies the paramedian thalami bilaterally. A young patient (in their early 30s) who presented with sudden onset of visual disturbance and speech difficulties is reported. A review of literature from 1981 to 2009 and review of the most widely reported clinical signs and symptoms are provided.