Biophysics and electrophysiology of pulsed field ablation in normal and infarcted porcine cardiac ventricular tissue.

Pulsed Field Ablation (PFA) is a new ablation method being rapidly adopted for treatment of atrial fibrillation, which shows advantages in safety and efficiency over radiofrequency and cryo-ablation. In this study, we used an in vivo swine model (10 healthy and 5 with chronic myocardial infarct) for ventricular PFA, collecting intracardiac electrograms, electro-anatomical maps, native T1-weighted and late gadolinium enhancement MRI, gross pathology, and histology. We used 1000-1500 V pulses, with 1-16 pulse trains to vary PFA dose.

MRI Accurately Visualizes RF Ablation Delivery Targeted to MRI-Defined Arrhythmia Substrates in the Left Ventricle.

Objective: Investigate the capacity of MRI to evaluate efficacy of radiofrequency (RF) ablations delivered to MRI-defined arrhythmogenic substrates.

Methods: Baseline MRI was performed at 3 T including 3D LGE in a swine model of chronic myocardial infarct (N = 8). MRI-derived maps of scar and heterogeneous tissue channels (HTCs) were generated using ADAS 3D.

MRI-Guided Cardiac RF Ablation for Comparing MRI Characteristics of Acute Lesions and Associated Electrophysiologic Voltage Reductions.

Objective: Radiofrequency (RF) energy delivered to cardiac tissue produces a core ablation lesion with surrounding edema, the latter of which has been implicated in acute procedural failure of Ventricular Tachycardia (VT) ablation and late arrhythmia recurrence. This study sought to investigate the electrophysiological characteristics of acute RF lesions in the left ventricle (LV) visualized with native-contrast Magnetic Resonance Imaging (MRI).

Methods: An MR-guided electrophysiology system was used to deliver RF ablation in the LV of 8 swine (9 RF lesions in total), then perform MRI and electroanatomic mapping.

Cine and late gadolinium enhancement MRI registration and automated myocardial infarct heterogeneity quantification.

Purpose: To develop an approach for automated quantification of myocardial infarct heterogeneity in late gadolinium enhancement (LGE) cardiac MRI.

Methods: We acquired 2D short-axis cine and 3D LGE in 10 pigs with myocardial infarct. The 2D cine myocardium was segmented and registered to the LGE images.

Cardiovascular magnetic resonance guided ablation and intra-procedural visualization of evolving radiofrequency lesions in the left ventricle.

Background: Radiofrequency (RF) ablation has become a mainstay of treatment for ventricular tachycardia, yet adequate lesion formation remains challenging. This study aims to comprehensively describe the composition and evolution of acute left ventricular (LV) lesions using native-contrast cardiovascular magnetic resonance (CMR) during CMR-guided ablation procedures.

Methods: RF ablation was performed using an actively-tracked CMR-enabled catheter guided into the LV of 12 healthy swine to create 14 RF ablation lesions.

Feasibility Study of Respiratory Motion Modeling Based Correction for MRI-Guided Intracardiac Interventional Procedures.

Goal: The purpose of this study is to improve the accuracy of interventional catheter guidance during intracardiac procedures. Specifically, the use of preprocedural magnetic resonance roadmap images for interventional guidance has limited anatomical accuracy due to intraprocedural respiratory motion of the heart. Therefore, we propose to build a novel respiratory motion model to compensate for this motion-induced error during magnetic resonance imaging (MRI)-guided procedures.

Frequencies of the defective CYP2C19 alleles responsible for the mephenytoin poor metabolizer phenotype in various Oriental, Caucasian, Saudi Arabian and American black populations.

The 4'-hydroxylation of S-mephenytoin is polymorphic in man. The poor metabolizer (PM) phenotype exhibits a lower frequency in Caucasians (2-5%) compared to Oriental populations (13-23%). Previous studies from our laboratory have described two mutations (CYP2C19m1 and CYP2C19m2) which account for approximately 100% of Oriental and approximately 85% of Caucasian PM alleles.

Nonketotic hyperglycinemia: A life-threatening disorder in Saudi newborns.

Nonketotic hyperglycinemia (NKH) is an autosomal recessive disorder due to a fundamental defect in the glycine cleavage system, which leads to neuronal dysfunction caused by two receptor-mediated mechanisms. It is a life-threatening condition in the neonate. Until now, the disease has not been described from Saudi Arabia.

The mephenytoin (cytochrome P450 2C 19) and dextromethorphan (cytochrome P450 2D6) polymorphisms in Saudi Arabians and Filipinos.

Hitherto no estimate has been available of the genetic polymorphisms of S-mephenytoin hydroxylation in the Saudi Arabian or any other Middle Eastern population. A total of 102 healthy Saudi Arabian volunteer subjects were tested simultaneously with mephenytoin and dextromethorphan. Two poor metabolizers of S-mephenytoin and two poor metabolizers of dextromethorphan were found.

Kohl: a hazardous eyeliner.

Kohl is a widely used traditional cosmetic. It is mainly worn around the eyes in the Middle East, Asia and Africa. The elemental composition of twenty-one kohl specimens originating from various parts of Saudi Arabia, India and the Middle East was determined by energy dispersive X-ray analysis (EDAX).

The reliability of estimates of interhemispheric transmission times derived from unimanual and verbal response latencies.

In this study, the reliability of estimates of interhemispheric transmission times derived from verbal and unimanual responses was assessed. Responses were made to presentations of lateralized light flashes in a series of 20 experimental sessions, with responses being made to stimuli presented at three different retinal eccentricities. The reliability of estimates of interhemispheric transmission across 20 experimental sessions was generally poorer for verbal compared to unimanual responses.