Randomized comparison of cavotricuspid isthmus ablation for atrial flutter using an open irrigation-tip versus a large-tip radiofrequency ablation catheter.

BACKGROUND: Large-tip (10 mm) catheters (LTCs) and open-irrigation-tip catheters (OITCs), both capable of creating large lesions, are more effective than conventional catheters for cavotricuspid isthmus (CTI) ablation. However, it is not clear whether complete CTI block can be achieved more efficiently using an LTC or an OITC. The purpose of this study was to compare the efficiency of radiofrequency catheter ablation (RFA) of the CTI using LTC versus OITC to eliminate atrial flutter (AFL). METHODS AND RESULTS: Sixty consecutive patients (age = 62 ± 10 years) with typical AFL were randomized to undergo RFA of CTI using an LTC (10 mm) or an OITC. If complete CTI block was not achieved by ≤30 minutes of RFA, patients were allowed to cross over to ablation with the other catheter. A 3-dimensional electroanatomical mapping system was used for catheter navigation only with the OITC. The mean duration of RFA to achieve CTI block in 50% of the patients was 6.8 ± 2.2 minutes with an LTC and 11.7 ± 2.7 minutes with an OITC (P = 0.001). After 30 minutes of RFA, CTI block was achieved in 26/30 (87%) and 25/30 patients (83%) using an LTC and an OITC, respectively (P = 1.0). After crossover, CTI block was achieved in 4/5 (80%) and in 4/4 patients (100%) with an LTC and OITC, respectively (P = 1.0). LTC was associated with a lower volume of intravenous fluid administration (388 ± 365 mL versus 865 ± 451 mL, P = 0.0001) and a trend for shorter procedure duration (95 ± 31 minutes versus 114 ± 50 minutes, P = 0.09) than the OITC. At 6 ± 3 months, 30/30 patients (100%) in the LTC and 27/30 patients (90%) in the OITC groups remained free from AFL, respectively (P = 0.24). Except for one inconsequential steam-pop during RFA with the OITC, there were no complications. CONCLUSIONS: Complete CTI block is achieved more rapidly using an LTC than an OITC, and with a similar clinical efficacy.

Prevalence and predictors of complications of radiofrequency catheter ablation for atrial fibrillation.

INTRODUCTION: Up to 6% of patients experience complications after radiofrequency catheter ablation (RFA) of atrial fibrillation (AF). The purpose of this study is to determine the prevalence and predictors of periprocedural complications after RFA for AF. METHODS AND RESULTS: The subjects were 1,295 consecutive patients (age = 60 ± 10 years) who underwent RFA (n = 1,642) for paroxysmal (53%) or persistent AF (47%) from January 2007 to January 2010. A complication occurred in 57 patients (3.5%); a vascular access complication in 31 (1.9%); pericardial tamponade in 20 (1.2%); a thromboembolic event in 4 (0.2%); deep venous thrombosis in 1 (<0.01%); and pulmonary vein stenosis in 1 patient (<0.01%). There were no procedure-related deaths. On multivariate analysis, female gender (OR = 2.27; ±95% CI: 1.31-2.57, P < 0.01) and procedures performed in July or August (OR = 2.10; ±95% CI: 1.16-3.80, P = 0.01) were independent predictors of any complication. For vascular complications, treatment with clopidogrel (OR = 4.40; ±95% CI: 1.43-13.53, P = 0.01), female gender (OR = 3.65; ±95% CI: 1.72-7.75, P < 0.01) and performing RFA in July or August (OR = 2.71; ±95% CI: 1.25-5.87, P = 0.01) were independent predictors. The only predictor of cardiac tamponade was prior RFA (OR = 3.32; ±95% CI: 0.95-11.61; P < 0.05). CONCLUSION: Prevalence of perioperative complications for RFA of AF is 3.5% and vascular access complications constitute the majority. The need for clopidogrel therapy should be carefully considered prior to RFA. At teaching institutions close supervision should be exercised during vascular access early in the year. Improvements in ablation technology and elimination of the need for repeat procedures may decrease the risk of pericardial tamponade.

Time to cardioversion of recurrent atrial arrhythmias after catheter ablation of atrial fibrillation and long-term clinical outcome.

INTRODUCTION: It is unclear whether early restoration of sinus rhythm in patients with persistent atrial arrhythmias after catheter ablation of atrial fibrillation (AF) facilitates reverse atrial remodeling and promotes long-term maintenance of sinus rhythm. The purpose of this study was to determine the relationship between the time to restoration of sinus rhythm after a recurrence of an atrial arrhythmia and long-term maintenance of sinus rhythm after radiofrequency catheter ablation of AF. METHODS AND RESULTS: Radiofrequency catheter ablation was performed in 384 consecutive patients (age 60 +/- 9 years) for paroxysmal (215 patients) or persistent AF (169 patients). Transthoracic cardioversion was performed in all 93 patients (24%) who presented with a persistent atrial arrhythmia: AF (n = 74) or atrial flutter (n = 19) at a mean of 51 +/- 53 days from the recurrence of atrial arrhythmia and 88 +/- 72 days from the ablation procedure. At a mean of 16 +/- 10 months after the ablation procedure, 25 of 93 patients (27%) who underwent cardioversion were in sinus rhythm without antiarrhythmic therapy. Among the 46 patients who underwent cardioversion at < or =30 days after the recurrence, 23 (50%) were in sinus rhythm without antiarrhythmic therapy. On multivariate analysis of clinical variables, time to cardioversion within 30 days after the onset of atrial arrhythmia was the only independent predictor of maintenance of sinus rhythm in the absence of antiarrhythmic drug therapy after a single ablation procedure (OR 22.5; 95% CI 4.87-103.88, P < 0.001). CONCLUSION: Freedom from AF/flutter is achieved in approximately 50% of patients who undergo cardioversion within 30 days of a persistent atrial arrhythmia after catheter ablation of AF.

Dietary Mg(2+) supplementation restores impaired vasoactive responses in isolated rat aorta induced by chronic ethanol consumption.

Chronic ethanol consumption contributes to cardiovascular dysfunction possibly related to loss of Mg(2+). This study was designed to examine the role of dietary Mg(2+) supplementation on chronic ethanol ingestion-induced vascular alteration. Rats were fed an ethanol liquid diet supplemented with or without Mg(2+) for 12 weeks. The force-generating capacity was examined in thoracic aortic rings. Ethanol-consuming animals exhibited significantly elevated blood pressure. In aorta with intact endothelium, the contractile responses to norepinephrine and KCl were greatly attenuated and potentiated, respectively. Interestingly, the ethanol-induced alterations in blood pressure and vasoconstrictive response were restored by Mg(2+) supplementation. Pretreatment with the beta(1)-adrenoceptor antagonist atenolol in intact aortic rings abolished the difference in response to norepinephrine between the control and ethanol groups, which implies the involvement of a weakened beta(1)-adrenoceptor component in vessels from the ethanol-fed rats. The norepinephrine-induced vasoconstriction in intact aorta rings was completely abolished by the alpha(1)-adrenoceptor antagonist prazosin. In endothelium-denuded aorta, the contractile response to norepinephrine or KCl was not significantly different between the ethanol and Mg(2+) groups. Endothelium-dependent vasorelaxation to carbamylcholine chloride was not altered by either ethanol or Mg(2+) supplementation. Sodium nitroprusside-induced vasorelaxation was depressed by ethanol, and restored by Mg(2+), in aorta with or without endothelium. These data suggest that chronic ethanol consumption contributes to alterations of endothelium-dependent and -independent vascular response. These alterations can be compensated by dietary Mg(2+) supplementation.

Importance of recognizing pseudo-septal infarction due to electrocardiographic lead misplacement.

Awareness of the problem of false electrocardiographic diagnosis of septal infarction due to cranially misplaced precordial leads V1 and V2, a common technical error, is important because this pseudo-pathologic finding can trigger unnecessary medical procedures and have other adverse sequelae. The non-trivial nature of this problem is emphasized by the case of a patient in whom the misdiagnosis caused loss of an employment opportunity. We demonstrate how P wave morphology in lead V2 can aid the clinician in suspecting erroneous right precordial lead placement in cases of apparent septal infarction. Ultimately, improved education of health care personnel regarding accurate precordial lead positioning technique is needed to minimize the occurrence of this electrocardiographic misdiagnosis.

Mapping and ablation of epicardial idiopathic ventricular arrhythmias from within the coronary venous system.

BACKGROUND: The prevalence of epicardial idiopathic ventricular arrhythmias that can be ablated from within the coronary venous system (CVS) has not been described. METHODS AND RESULTS: In a consecutive group of 189 patients with idiopathic ventricular arrhythmias referred for ablation, the site of origin (SOO) of ventricular tachycardia and/or premature ventricular contractions was determined by activation mapping and pace mapping. Mapping was performed within the CVS if endocardial mapping did not reveal an SOO. Venography of the CVS and coronary angiography were performed before ablation in the CVS. In 27 of 189 patients (14%+/-5%; 95% confidence interval), the SOO of the ventricular arrhythmia was identified from within the coronary venous system, either in the great cardiac vein (n=26) or the middle cardiac vein (n=1). The mean activation time at the SOO was -29+/-8 ms. Twenty of 27 patients (74%) underwent successful ablation within the CVS. Epicardial ventricular arrhythmias displayed a broader R wave in V(1) compared with arrhythmias in the control group (85 ms [interquartile range, 40] versus 65 ms [interquartile range, 95]; P<0.01). Two patients had recurrent premature ventricular contractions within 2 weeks after ablation, and no recurrences occurred in the remaining patients during a median follow-up of 13 months (range, 25). In the 7 patients with unsuccessful ablation, failure was because the ablation catheter could not be advanced to the SOO within the great cardiac vein (n=4), inadequate power delivery at the SOO (n=1), proximity to the phrenic nerve (n=1), or proximity of the SOO to a major coronary artery (n=1). Transcutaneous epicardial ablation was effective in 1 of 2 patients in whom it was attempted. CONCLUSIONS: Almost 15% of idiopathic ventricular arrhythmias have an epicardial origin. ECG characteristics help to differentiate epicardial arrhythmias from endocardial ventricular arrhythmias. The SOO of epicardial arrhythmias can be ablated from within the CVS in approximately 70% of patients.

Relationship between burden of premature ventricular complexes and left ventricular function.

BACKGROUND: Frequent idiopathic premature ventricular complexes (PVCs) can result in a reversible form of left ventricular dysfunction. The factors resulting in impaired left ventricular function are unclear. Whether a critical burden of PVCs can result in cardiomyopathy has not been determined. OBJECTIVE: The objective of this study was to determine a cutoff PVC burden that can result in PVC-induced cardiomyopathy. METHODS: In a consecutive group of 174 patients referred for ablation of frequent idiopathic PVCs, the PVC burden was determined by 24-hour Holter monitoring, and transthoracic echocardiograms were used to assess left ventricular function. Receiver-operator characteristic curves were constructed based on the PVC burden and on the presence or absence of reversible left ventricular dysfunction to determine a cutoff PVC burden that is associated with left ventricular dysfunction. RESULTS: A reduced left ventricular ejection fraction (mean 0.37 +/- 0.10) was present in 57 of 174 patients (33%). Patients with a decreased ejection fraction had a mean PVC burden of 33% +/- 13% as compared with those with normal left ventricular function 13% +/- 12% (P <.0001). A PVC burden of >24% best separated the patient population with impaired as compared with preserved left ventricular function (sensitivity 79%, specificity 78%, area under curve 0.89) The lowest PVC burden resulting in a reversible cardiomyopathy was 10%. In multivariate analysis, PVC burden (hazard ratio 1.12, 95% confidence interval 1.08 to 1.16; P <.01) was independently associated with PVC-induced cardiomyopathy. CONCLUSION: A PVC burden of >24% was independently associated with PVC-induced cardiomyopathy.

Influence of hypertension on tetrahydropapaveroline-induced vasorelaxation in rat thoracic aorta.

Tetrahydropapaveroline (THP), a condensation product of ethanol-derived acetaldehyde, has been shown to elicit a vasorelaxant response in rat thoracic aorta. This study examined the influence of hypertension on the THP-induced vasorelaxant responsiveness. Ring segments of thoracic aorta were isolated from Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR) and isometric tension development was measured with a force transducer. In aorta, with or without intact endothelium, the contractile responses to potassium chloride (0-120 mM) were comparable between the WKY and the SHR groups. Hypertension did not affect the vasoconstrictive response to norepinephrine (0-10 microM) in vessels with intact endothelium, whereas it attenuated the norepinephrine-induced response in vessels without endothelium. THP (0.1-100 microM) elicited endothelium-intact as well as -denuded vasorelaxation in aorta from both WKY and SHR groups. Interestingly, the THP-induced endothelium-dependent vasorelaxation was significantly enhanced, whereas the THP-induced endothelium-independent vasorelaxation was not affected by hypertension. These data indicate that the THP-induced endothelium-dependent vasorelaxant response is altered by the hypertensive state.