EFFECT OF NEOSTIGMINE AND PYRIDOSTIGMINE ON THE PLASMA CHOLINESTERASE ACTIVITY

The effect of neostigmine 0.05mg kg^–1 or pyridostigmine0.25mg kg^–1 on serum cholinesterase activity was investigatedin 20 adult patients undergoing elective surgery. Both drugsproduced marked depression of enzymatic activity. The maximaldepression was observed in samples taken 5mm after injection.The maximal percentage depression of enzymatic activity wasnot significantly different in the two drug groups. However,at 30–60mm after injection, the degree of depression wasless in the neostigmine group. This may be attributed to thedifferent plasma clearances of neostigmine and pyridostigmine.     

Left Atrial Appendage Dimensions Predict the Risk of Stroke/TIA in Patients With Atrial Fibrillation

Risk of Stroke/TIA in Patients With Atrial Fibrillation. Introduction: Most strokes in patients with atrial fibrillation (AF) arise from thrombus formation in left atrial appendage (LAA). Our aim was to identify LAA features associated with a higher stroke risk in patients with AF using magnetic resonance imaging and angiography (MRI/MRA). Methods: The study included 144 patients with nonvalvular AF who were not receiving warfarin and who underwent MRI/MRA prior to catheter ablation for AF. LAA volume, LAA depth, short and long axes of LAA neck, and numbers of lobes were measured. Results: Of the 144 patients, 18 had a prior stroke or transient ischemic attack (TIA) (13 and 5, respectively). Compared with patients who had no history of stroke/TIA, these patients were older, had higher prevalence of hypertension and hyperlipidemia and had higher LAA volume (22.9 ± 9.6 cm³ vs. 14.5 ± 7.1 cm³, P < 0.001). Their LAA depth (3.76 ± 0.9 cm vs. 3.21 ± 0.8 cm, P = 0.006) and the long and short axes of the LAA neck (3.12 ± 0.7 cm vs. 2.08 ± 0.7 cm, P < 0.001; 2.06 ± 0.5 cm vs. 1.37 ± 0.4 cm, P < 0.001, respectively) were larger. Using stepwise logistic regression model, the only statistically significant multivariable predictors of events were age (OR = 1.21 per year, 95% CI 1.06‐1.38, P = 0.004), aspirin use (OR = 0.039, 95% CI 0.005‐0.28, P = 0.001), and LAA neck dimensions (short axis × long axis) (OR = 3.59 per cm², 95% CI 1.93‐6.69, P < 0.001). Conclusion: LAA dimensions predict strokes/TIAs in patients with AF. LAA assessment by MRI/MRA can potentially be used as an adjunctive tool for risk stratification for embolic events in AF patients. (J Cardiovasc Electrophysiol, Vol. 22, pp. 10‐15, January 2011)     

Pitfalls of Programming Sensing Polarities Using the Coronary Sinus Lead in Biventricular Pacemakers

Knowledge of the available sensing polarities in biventricular pacemakers is necessary for appropriate troubleshooting and avoiding possible pitfalls of cardiac resynchronization therapy programming, as illustrated through this case presentation. (PACE 2011; 34:e22–e25)     

ALPHA-LIPOIC ACID AMELIORATES MYOCARDIAL TOXICITY INDUCED BY DOXORUBICIN

The effect of alpha-lipoic acid (LA) on the cardiotoxicity induced by doxorubicin (DOX) was investigated. A single dose of DOX (15 mg kg(-1), i.p) induced cardiotoxicity manifested biochemically by a significant elevation of serum creatine phosphokinase (CK; EC: 2.7.3.2) and lactate dehydrogenase (LDH; EC: 1.1.1.27) 48 h later. Moreover, cardiotoxicity was further confirmed by the significant increase in lipid peroxides measured as malondialdehyde (MDA), and significant decrease in protein thiols (Protein-SH) content in heart tissues. Administration of LA (100 mg kg(-1)) orally for 5 days before and 2 days after DOX injection produced a significant protection against cardiotoxicity induced by DOX. The amelioration of cardiotoxicity was evident by significant reductions in serum CK and LDH. Moreover, LA prevented the rise of MDA as well as the significant reduction of Protein-SH. These results may suggest that LA has a protective effect against cardiotoxicity induced by DOX and it may, therefore, improve the therapeutic index of DOX.     

Mapping and Ablation of Atypical AVNRT from the Morphologic Left Atrium in a Patient with Dextrocardia and Situs Inversus

A 75‐year‐old woman with dextrocardia, situs inversus, and subpulmonic outflow obstruction presented with recurrent supraventricular tachycardia (SVT). This SVT was easily inducible during electrophysiology study, and pacing maneuvers during SVT were consistent with atypical, slow‐slow atrioventricular nodal reentrant tachycardia (AVNRT). The His bundle was identified in the low postero‐septal morphologic right atrium, at the typical anatomic site for slow pathway ablation of AVNRT. Mapping of the retrograde earliest atrial electrogram during AVNRT localized this site to the mid‐septal morphologic left atrium, and cryoablation at this site terminated the AVNRT and rendered it noninducible. (PACE 2010; e106–e109)     

Incidence and Electrophysiologic Properties of Dissociated Pulmonary Vein Activity Following Pulmonary Vein Isolation During Catheter Ablation of Atrial Fibrillation

Dissociated PV Activity During AF Ablation. Introduction: Pulmonary veins (PV) play an important role in the arrhythmogenesis of atrial fibrillation (AF). Catheter‐based PV isolation is one of the primary treatments for symptomatic drug refractory AF. Following electrical isolation, isolated rhythms in the PV are encountered. The aim of this study was to assess the frequency of postisolation PV activity and classify the different rhythms observed. Methods and Results: This single center prospective study sought to assess the dissociated activity in the PVs following their isolation during AF ablation. In 100 consecutive patients (60 paroxysmal, 40 persistent) undergoing AF ablation, dissociated PV activity was recorded using a multielectrode mapping catheter following antral PV isolation. The dissociated PV activity was classified as (1) silent, (2) isolated ectopic beats, (3) ectopic rhythm, and (4) PV fibrillation. All the PVs were successfully isolated in all the patients. In 91 of 100 patients, there was dissociated activity in at least 1 isolated ipsilateral PV group. There was no significant difference in spontaneous PV activity between patients with paroxysmal and persistent AF (91.7% vs 90%, P = 1.0). Among the 200 isolated ipsilateral PV groups, 64 of 200 (32%) were silent, 86 of 200 (43%) demonstrated isolated ectopic beats, 41 of 200 (20.5%) had ectopic rhythms and 9 of 200 (4.5%) had PV fibrillation. The average cycle length of the PV ectopic rhythm was 2594 ± 966 ms (range 1193–4750 ms). Conclusions: Following PV isolation, a majority of patients demonstrate dissociated activity in at least 1 PV. This finding was evident in patients with both paroxysmal and persistent AF. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1338‐1343, December 2010)