Showing papers by "Hui Nam Pak published in 2006"

Role of the posterior papillary muscle and purkinje potentials in the mechanism of ventricular fibrillation in open chest dogs and Swine: effects of catheter ablation.

Abstract: Effects of Catheter Ablation. Background: Papillary muscle (PM) ablation may terminate ventricular fibrillation (VF) in rabbit hearts. Whether or not PM ablation prevents ventricular fibrillation (VF) induction in large animals is unknown. Methods: We performed noncontact endocardial mapping and/or high-density epicardial mapping during VF in 12 dogs and 16 swine and tested the effects of posterior PM (PPM) ablation on VF inducibility. Results: During VF in progressive global ischemia (3 swine and 2 dogs), the highest dominant frequency (DF) was near PPM. The majority of the reentrant wavefronts during a propranolol infusion (swine) were anchored to the PPM. Purkinje potentials onset were recorded on the PPM both during sinus rhythm and during VF. Radiofrequency (RF) ablation of the endocardium on the PPM with a linear extension of the ablation line from the PPM to the mitral valve annulus and then the left ventricular apex in 7 dogs reduced the VF inducibility from 100% at baseline to 22% after ablation (P < 0.0001). RF applications to the anterolateral wall of dogs (n = 3) did not prevent VF induction. The application of RF energy near the PPM frequently initiated VF in swine (n = 7), preventing subsequent testing of VF inducibility. Conclusion: In dogs and swine, the highest DF and majority of reentrant wavefronts during VF with acute global ischemia or during a propranolol infusion were located on the PPM. RF ablation targeted at the PPM reduced the inducibility of VF in normal dogs. However, the same ablation provoked incessant VF in swine, preventing subsequent testing of VF inducibility.

Electroanatomic characteristics of atrial premature beats triggering atrial fibrillation in patients with persistent versus paroxysmal atrial fibrillation.

Abstract: UNLABELLED APBs in Persistent Versus Paroxysmal AF. BACKGROUND Although the electrical disconnection between the left atrium (LA) and pulmonary veins (PVs) by radiofrequency catheter ablation has been proven to be effective in controlling atrial fibrillation (AF), the recurrence rate is higher in patients with persistent AF (PeAF) than with paroxysmal AF (PAF). We hypothesized that the origin of the atrial premature beats (APBs) that trigger AF and the pattern of their breakthrough into the LA differ between PAF and PeAF. METHODS We mapped 75 APBs (53 APBs triggering AF, 22 isolated APBs) from the LA and PVs in 26 patients with AF (age: 49.5 +/- 9.6, males: 23, PAF = 17, PeAF = 9), using a noncontact endocardial mapping (NCM) system. The location of the preferential conduction (PC) sites and their conduction velocity (CV) were compared. RESULTS In patients with PeAF, the earliest activation (EA) site and exit of the PC were more frequently located on the LA side of the LA-PV junction as compared with PAF (P < 0.001). Eighty-one percent of the PCs were located in the area between the left and right superior PVs. The incidence of PCs was similar between the PeAF and PAF patients (P = NS). PCs were more commonly found with APBs inducing AF (63.3%) than with those not inducing AF (35.2%, P = 0.01). The CV of the PC was slower for PeAF than PAF (P < 0.001). The CV in the LA during sinus rhythm was also slower for PeAF than PAF (P < 0.01). CONCLUSION PeAF was more frequently triggered by APBs from the LA side of the LA-PV junction than PAF and resulted in slower conduction than did PAF. These findings may help explain the higher potential for recurrence after electrical PV isolation in patients with PeAF.

Epicardial ablation of ventricular tachycardia associated with isolated ventricular noncompaction

Abstract: A 52-year-old man presented with sudden onset of palpitations and dizziness. Echocardiogram confirmed the diagnosis of isolated noncompaction of ventricular myocardium with moderated systolic dysfunction, and the electrocardiogram (ECG) revealed ventricular tachycardia (VT), of which the focus seemed to match an area of prominent left ventricular noncompaction on the 12-lead surface ECG. Through the activation mapping from the endo- and epicardium, simultaneously, a discrete potential preceding the QRS during VT was observed at the anterolateral epicardial wall. He subsequently underwent radiofrequency ablation, and VT was successfully eliminated.

Torsade de pointes induced by short-term oral amiodarone therapy.

Abstract: Although amiodarone appears to have few pro-arrhythmic effects, torsade de pointes (TdP) has been observed during long-term drug administration, usually in conjunction with electrolyte disturbances, a change in drug dosage, or concomitant drug therapy. We report two cases of amiodarone-induced TdP shortly after administration of a low dose of oral amiodarone, in the absence of predisposing factors.

Use of Three‐Dimensional Mapping Systems in the Catheter Ablation of Atrial Fibrillation

Abstract: Three-Dimensional Mapping Systems. The increasing clinical experience with remarkable advancement in the technology has enabled the catheter ablation of atrial fibrillation (AF) to become more effective and safe. Widespread utilization of three-dimensional (3D) mapping systems has facilitated the improvement in the outcomes after catheter ablation of AF. The purpose of this article is to review the current status, clinical role, and future directions of various 3D mapping systems in catheter ablation of AF.

Electrocardiographic Manifestations of Cardiac Metastasis in Lung Cancer

Abstract: We describe a case of primary lung cancer with myocardial metastasis, documented with electrocardiogram (ECG) mimicking myocardial ischemia and manifesting VT. Metastatic tumor to the myocardium proper is uncommon and difficult to diagnose because of nonspecific signs and symptoms. We observed such ECG changes in this case were initially misinterpreted as acute coronary syndrome. The diagnosis of cardiac metastasis was confirmed by contrast-enhanced magnetic resonance imaging and computed tomography.