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Background: Right ventricular apical (RVA) pacing promotes tricuspid regurgitation (TR), electromechanical dyssynchrony, and ventricular dysfunction.We tested a novel intramyocardial bipolar lead to assess whether stimulation of the atrioventricular septum (AVS) produces synchronous ventricular activation without crossing the tricuspid valve (TV). Methods: A lead with an active external helix and central pin was placed on the AVS and the RVA in three dogs. High-density electroanatomic (EA) mapping was performed of both ventricles endocardially and epicardially. Intracardiac echocardiography was used to access ventricular synchrony. Results: The lead was successfully deployed into the AVS in all cases with consistent capture of the ventricular myocardium without atrial capture or sensing. The QRS duration was less with AVS compared with RVA pacing (89 ± 4 ms vs. 100 ± 11 ms [P < 0.0001, GEE P = 0.03]). There was decreased delay between color Doppler M-mode visualized peak contraction of the septum and the mid left ventricular free wall with AVS compared with RVA pacing (89 ± 91 ms vs. 250 ± 11 ms [P < 0.0001, GEE P = 0.006]). Activation time between themid septum and mid free wall was shorter with AVS versus RVA pacing (20.4± 7.7 vs. 30.8 ± 11.6 [P = 0.01, GEE P = 0.07]). The interval between QRS onset to earliest free wall activation was shorter with AVS vs. RVA pacing (19.2 ± 6.4 ms vs. 31.1 ± 11.7 ms [P = 0.005, GEE P = 0.02]). Conclusion: The AVS was successfully paced in three dogs resulting in synchronous ventricular activation without crossing the TV. [ABSTRACT FROM AUTHOR]

The mechanisms underlying the triggers and maintenance of atrial fibrillation (AF) are not fully understood. One potential unproved mechanism is that gastroesophageal reflux disease (GERD), in which acid reflux induces local and systemic inflammation, may increase triggered activity in the myocardium and pulmonary veins and increase AF risk. A self-report questionnaire was mailed to a random sample of 5,288 residents of Olmsted County, Minnesota, aged 25 to 74 years to assess the presence and frequency of GERD from 1988 to 1994. The long-term risk for AF over a period of 11.4 +/- 5.0 years was determined through review of clinical evaluations and the electrocardiographic database in those without previous AF. The average age was 53 +/- 17 years, and 2,571 subjects (49%) were man. Of these patients, 741 developed AF (cumulative probability of AF at 18 years 20%, 95% confidence interval [CI] 17% to 22%). Age (hazard ratio [HR] 1.09, 95% CI 1.08 to 1.10, p <0.001), male gender (HR 1.81, 95% CI 1.53 to 2.14, p <0.001), hypertension (HR 1.36, 95% CI 1.14 to 1.61, p = 0.0006), and heart failure (HR 1.74, 95% CI 1.16 to 2.60, p = 0.007) were independently associated with the risk of AF. The presence of any GERD was not associated with risk for AF (HR 0.81, 95% CI 0.68 to 0.96, p = 0.014) after adjustment for other risk factors. The frequency of GERD did not significantly affect the risk for AF, although patients with more frequent GERD had a slightly higher AF risk. Esophagitis increased the risk for AF (HR 1.94, 95% CI 1.35 to 2.78, p <0.001), but the association did not persist when accounting for other risk factors (p = 0.72). In conclusion, in this large population-based study of patients surveyed for GERD, no association was found with the presence or frequency of symptoms and AF. Patients with esophagitis were more likely to develop AF, although this association requires further study. [ABSTRACT FROM AUTHOR]

INTRODUCTION: Junctional tachycardia (JT) and atrioventricular nodal reentrant tachycardia (AVNRT) can be difficult to differentiate. Yet, the two arrhythmias require distinct diagnostic and therapeutic approaches. We explored the utility of the delta H-A interval as a novel technique to differentiate these two tachycardias. METHODS: We included 35 patients undergoing electrophysiology study who had typical AVNRT, 31 of whom also had JT during slow pathway ablation, and four of whom had spontaneous JT during isoproterenol administration. We measured the H-A interval during tachycardia (H-A(T)) and during ventricular pacing (H-A(P)) from the basal right ventricle. Interobserver and intraobserver reliability of measurements was assessed. Ventricular pacing was performed at approximately the same rate as tachycardia. The delta H-A interval was calculated as the H-A(P) minus the H-A(T). RESULTS: There was excellent interobserver and intraobserver agreement for measurement of the H-A interval. The average delta H-A interval was -10 ms during AVNRT and 9 ms during JT (P < 0.00001). For the diagnosis of JT, a delta H-A interval >or= 0 ms had the sensitivity of 89%, specificity of 83%, positive predictive value of 84%, and negative predictive value of 88%. The delta H-A interval was longer in men than in women with JT, but no gender-based differences were seen with AVNRT. There was no difference in the H-A interval based on age

BACKGROUND: Propofol infusion syndrome is first manifest by unexplained metabolic acidosis. Its incidence is unknown. METHODS: Charts of all patients undergoing nonsurgical, catheter radiofrequency ablation for atrial flutter or fibrillation from 1999 through 2001 at Mayo Clinic Rochester, who received propofol and had an arterial blood gas drawn during the procedure, were reviewed retrospectively for metabolic acidosis, prospectively defined as base excess -2 or less. Of 301 radiofrequency ablation cases, 55 had an arterial blood gas. Virtually all radiofrequency ablation patients received propofol, so they could not be used as nonpropofol controls. Instead, all carotid endarterectomy patients in 2000 who did not receive propofol and had an arterial blood gas drawn after anesthetic induction and before surgical incision were used as a comparator group. RESULTS: In propofol radiofrequency ablation patients with no apparent cause of metabolic acidosis besides propofol, 13 of 55 (24%) had base excess of -2 or less, versus 22 of 267 carotid patients (8.2%) (P<0.01). Maximal negative base excess was -4.2+/-1.7 in these propofol patients and was not correlated with propofol dose, age, or fluid dose, versus base excess of -3.2+/-1.5 in carotid patients (P>0.05). Propofol patients received prolonged anesthetics (7 h) and high-dose propofol (20 mg/kg). CONCLUSIONS: This is the first incidence estimate of metabolic acidosis during prolonged propofol infusion and suggests that it is not rare. The study is limited by its retrospective nature and by the lack of baseline arterial blood gas data and will require confirmation by prospective study. [ABSTRACT FROM AUTHOR]

Introduction: We observed a change in the atrial activation sequence during radiofrequency (RF) energy application in patients undergoing left accessory pathway (AP) ablation. This occurred without damage to the AP and in the absence of a second AP or alternative arrhythmia mechanism. We hypothesized that block in a left atrial 'isthmus' of tissue between the mitral annulus and a left inferior pulmonary vein was responsible for these findings. Methods and Results: Electrophysiologic studies of 159 patients who underwent RF ablation of a left free-wall AP from 1995 to 1999 were reviewed. All studies with intra-atrial conduction block resulting from RF energy delivery were identified. Fluoroscopic catheter positions were reviewed. Intra-atrial conduction block was observed following RF delivery in 11 cases (6.9%). This was evidenced by a sudden change in retrograde left atrial activation sequence despite persistent and unaffected pathway conduction. In six patients, reversal of eccentric atrial excitation during orthodromic reciprocating tachycardia falsely suggested the presence of a second (septal) AP. A multipolar coronary sinus catheter in two patients directly demonstrated conduction block along the mitral annulus during tachycardia. Conclusion: An isthmus of conductive tissue is present in the low lateral left atrium of some individuals. Awareness of this structure may avoid misinterpretation of the electrogram during left AP ablation and may be useful in future therapies of atypical atrial flutter and fibrillation. [ABSTRACT FROM AUTHOR]

Surrogate electro-anatomic-derived geometries are used as the three-dimensional (3D) basis for mapping of cardiac arrhythmias. While merged computed tomography (CT) imaging may provide stellar pulmonary vein (PV) and left atrial (LA) anatomy, the applied scans must be obtained prior to ablation, and may not reflect physiologic conditions at the time of intervention. Patient-specific, ultrasound-derived 3D imaging has been developed as an alternative basis for new generation electro-anatomic mapping. An electro-anatomic sensor positioned at the tip of the phased-array intracardiac ultrasound catheter, provides the means to specify both location and orientation of each image as the 'context' for creating the 3D volumes for co-registration with electro-anatomic mapping. Specific anatomic details such as the pulmonary veins, membranous fossa, papillary muscles, or valve structures derived from real-time imaging can also be integrated into each segmented volume. This presentation reviews the basis and methods for this novel multi-modality image fusion for the creation of robust, nearly real-time anatomic images for guiding electro-anatomic mapping and ablation without requiring pre-acquired CT image sets, with accompanying limitations. [ABSTRACT FROM AUTHOR]

Atrial fibrillation (AF) is the most common arrhythmia encountered in clinical practice. Its increasing prevalence, particularly among the elderly, renders it one of the most serious current medical epidemics. Several management questions confront the clinician treating a patient with AF: Should the condition be treated? Is the patient at risk of death or serious morbidity as a result of this diagnosis? If treatment is necessary, is rate control or rhythm control superior? Which patients need anticoagulation therapy, and for how long? This review of articles obtained by a search of the PubMed and MEDLINE databases presents the available evidence that can guide the clinician in answering these questions. After discussing the merits of available therapy, including medications aimed at controlling rate, rhythm, or both, we focus on the present status of ablative therapy for AF. Catheter ablation, particularly targeting the pulmonary veins, is being increasingly performed, although the precise indications for this approach and its effectiveness and safety are being actively investigated. We briefly discuss other invasive options that are less frequently used, such as pacemakers, defibrillators, left atrial appendage closure devices, and the surgical maze procedure. [ABSTRACT FROM AUTHOR]

Objective: To describe and evaluate the in-hospital treatment of ventricular arrhythmias and underlying structural heart disease in patients who survive ventricular fibrillation (VF) out-of-hospital cardiac arrest (OHCA) in a region with a high survival rate after hospital discharge.Patients and Methods: The study included all patients presenting in Olmsted County, Minnesota, who had experienced OHCA between November 1990 and December 2000 and who underwent defibrillation of VF by an emergency medical service system.Results: Of 200 patients who experienced VF arrest, 138 (69%) survived to hospital admission (7 died in the emergency department before admission), and 79 (40%) were discharged. Of patients who were discharged, 37 (47%) had a reversible cause of the arrest (perimyocardial infarction) and received treatment of the primary process. The other 42 patients who were discharged had ischemic coronary heart disease (CHD) (n=25), nonischemic CHD (n=10), or idiopathic VF (n=7). Four of the patients with CHD but no left ventricular dysfunction were treated with coronary artery bypass grafting or percutaneous coronary intervention alone. A total of 52 patients (66%) were candidates for electrophysiologic testing. Of these patients, 48 (92%) underwent electrophysiologic testing; of these patients, 10 received amiodarone alone, and 35 received an implantable cardioverter-defibrillator (ICD) (of whom 3 also received amiodarone). Patients who did not receive ICD therapy typically presented before 1998 with CHD and underwent coronary artery bypass grafting or percutaneous coronary intervention only. Of 79 patients who were discharged, 14 (18%) with an ICD have received subsequent shocks. Nineteen (24%) of 79 patients have died, 5 of a primary cardiac etiology (including 2 with repeated OHCA).Conclusions: The VF OHCA survival rate is high in the setting of rapid defibrillation, with 40% of patients being discharged from the hospital. By the end of the 10-year study, more patients were receiving antiarrhythmic therapy, in particular ICD implantation, after hospital admission. Overall, the long-term survival in patients with VF OHCA is favorable. [ABSTRACT FROM AUTHOR]

Objectives: We evaluated left atrial appendage obliteration in high-risk patients with atrial fibrillation (AF).Background: Left atrial appendage thrombosis and embolization is the principal mechanism of stroke in AF. Anticoagulation is underutilized and often contraindicated.Methods: Thoracoscopic Left Appendage, Total Obliteration, No cardiac Invasion (LAPTONI) was undertaken with a loop snare in eight patients and a stapler in seven patients, median age 71 years, with clinical risk factors for stroke and with an absolute contraindication to or failure of prior thrombosis prevention with warfarin. Eleven patients had a history of prior thromboembolism. One patient took sustained warfarin during follow-up.Results: The LAPTONI procedure was completed in 14 of 15 patients, and 1 patient required urgent conversion to open thoracotomy because of bleeding. Patients have been followed up for 8 to 60 months, mean 42 +/- 14 months. One fatal stroke occurred 55 months after surgery, and one non-disabling stroke three months after surgery. Two other deaths occurred, one after coronary bypass surgery and the other from hepatic failure. The subgroup of 11 patients with prior thromboembolism had an annualized rate of stroke of 5.2% per year (95% confidence interval [CI] 1.3 to 21) after LAPTONI, which compares to a rate of 13% per year (95% CI 9.0 to 19) for similar aspirin-treated patients from the Stroke Prevention in Atrial Fibrillation trials (p = 0.15).Conclusions: The LAPTONI procedure appears technically feasible without immediate disabling neurologic morbidity or mortality, and it demonstrates low post-operative event rates and a statistical trend toward thromboembolic risk reduction in high-risk AF patients. [ABSTRACT FROM AUTHOR]