Arrhythmia Burden In Patients Research Articles

KATP vs Purkinje fibers: Which should we shoot first, or should we?

backs. 4 ICDs, which are widely used to prevent arrhythmic SCDs, can also deliver inappropriate shocks that can not only damage the diseased heart but also provoke arrhythmias. In spite of these shortcomings, ICDs are the only available therapy that can effectively terminate VF soon after it initiates. Moreover, select antiarrhythmic medications such as beta-blockers and amiodarone are used to reduce the frequency of ICD shocks but are associated with undesirable side effects. 5 Additionally, ablation of proarrhythmic ventricular tissue can decrease the number of ICD shocks but does not significantly alter mortality rate and potentially can result in multiple complications 6 possibly due to electroporation damage. 7 Therefore, identifying novel mechanisms and therapeutic strategies to effectively treat malignant arrhythmias such as VF is an absolute necessity to improve prognosis for the growing population with cardiac disease. One important approach to achieve this goal is to determine the cellular basis of these fatal arrhythmias. Historically, ion channels that maintain normal electrical homeostasis across the cell membrane are the primary candidates to treat arrhythmias. The ATP-sensitive potassium current IK(ATP) is one such ion current that plays an important role in cardiac repolarization and contraction during both physiologic and especially pathologic conditions. 8 Specifically, KATP channels are known to play a cardioprotective role during myocardial ischemia and hypoxia, wherein the increased potassium efflux causes a reduction in action potential duration. Although beneficial, the anatomically heteterogeneous decrease in action potential duration and hence dispersed refractoriness also can increase the propensity for VF. 9–11 Experimental manipulation of the KATP channels using channel openers (e.g., pinacidil and diazoxide) and inhibitors (e.g., glibenclamide) has clearly established the channel’s role in the induction and maintenance of VF in different animal models, 8,12 explanted human hearts, 9 and in non–insulin-dependent diabetic patients during transient ischemia. 13 Clearly, activation of KATP channels could be one mechanism of ischemia-induced VF, especially in diseased, metabolically challenged hearts. Another important player implicated in VF development is the Purkinje fiber system (PS), where triggered activity has been proposed to initiate as well as maintain VF. 14,15 Premature beats originating in the PS may initiate VF, and ablation focused on these fibers can reduce the arrhythmic burden in patients with idiopathic VF. 14 In the canine heart,

Association of sodium and potassium intake with ventricular arrhythmic burden in patients with essential hypertension

Abstract Background Hypertensive populations suffer from an increased susceptibility to ventricular arrhythmias and sudden cardiac death. A high-salt diet appears to be a major factor involved in cardiovascular complications in hypertension. We examined the relationship between dietary salt and potassium, as indicated by urinary sodium (UNa), urinary potassium (UK), and urinary sodium/potassium ratio (UNa/K), and the arrhythmic burden in patients with essential hypertension. Methods We included 255 consecutive adult patients with well-controlled hypertension who were being followed in the hypertension outpatient clinic of a university tertiary hospital and complained of episodes of atypical chest pain and/or palpitations. All underwent 24-hour ambulatory electrocardiograph monitoring and their UNa, UK, and UNa/K ratio from 24-hour urinary excretion specimens were evaluated. Results No significant correlation was found between premature supraventricular contractions and the parameters that were examined. However, the percentage of premature ventricular contractions (PVC%) showed a weak positive association with UNa (r = 0.2; P = .001) and a moderate negative association with UK (r = −0.396; P P Conclusions A higher UNa/UK excretion ratio is significantly associated with PVCs, indicating an increased susceptibility to ventricular arrhythmias even among hypertensives with well-controlled blood pressure. Our findings reinforce recommendations for dietary interventions in those populations.

Association of sodium and potassium intake with ventricular arrhythmic burden in patients with essential hypertension

BackgroundHypertensive populations suffer from an increased susceptibility to ventricular arrhythmias and sudden cardiac death. A high-salt diet appears to be a major factor involved in cardiovascular complications in hypertension. We examined the relationship between dietary salt and potassium, as indicated by urinary sodium (UNa), urinary potassium (UK), and urinary sodium/potassium ratio (UNa/K), and the arrhythmic burden in patients with essential hypertension. MethodsWe included 255 consecutive adult patients with well-controlled hypertension who were being followed in the hypertension outpatient clinic of a university tertiary hospital and complained of episodes of atypical chest pain and/or palpitations. All underwent 24-hour ambulatory electrocardiograph monitoring and their UNa, UK, and UNa/K ratio from 24-hour urinary excretion specimens were evaluated. ResultsNo significant correlation was found between premature supraventricular contractions and the parameters that were examined. However, the percentage of premature ventricular contractions (PVC%) showed a weak positive association with UNa (r = 0.2; P = .001) and a moderate negative association with UK (r = −0.396; P < .001). The partial correlation coefficient of PVC% with the UNa/UK ratio remained significant even after controlling for left ventricular mass index (r = 0.437; P < .001). ConclusionsA higher UNa/UK excretion ratio is significantly associated with PVCs, indicating an increased susceptibility to ventricular arrhythmias even among hypertensives with well-controlled blood pressure. Our findings reinforce recommendations for dietary interventions in those populations.

EFFECT OF ENDOEPICARDIAL PERCUTANEOUS LEFT ATRIAL APPENDAGE LIGATION (LARIAT) ON ARRHYTHMIA BURDEN IN PATIENTS WITH ATRIAL FIBRILLATION

Left atrial appendage is a very common non Pulmonary venous source of triggered activity. Electrical isolation of LAA seems to be effective in improving outcomes of RF ablation. It is not clear how ligation of the LAA impacts arrhythmia burden in patients with AF We prospectively followed AF

Time for change: Cardiac neurophysiology meets cardiac electrophysiology

The cardiovascular autonomous neural system represents an integrative fiber network that regulates cardiovascular hemodynamic and electrophysiological processes. During normal physiology, the autonomic nervous system represents a short latency responder that quickly compensates for temporary changes of cardiac function (eg, pumping force, blood pressure, and heart rate). However, when compensation becomes permanent during cardiovascular disease, specifically sympathetic activation catalyzes a further deterioration of the disease process. Besides functional effects on heart rate, inotropy, vasomotion, and cardiac electrophysiology, the sympathetic/parasympathetic nervous systems exert profound pro-/anti-inflammatory effects. There are circumstances in which the parasympathetic branch may play a dominant negative role: during neurocardiogenic syncope, an exaggerated parasympathetic tone acts as a final common pathway resulting in bradycardia and/ or vasodilatation. Likewise, in some forms of paroxysmal atrial fibrillation, predominance of vagally mediated shortening of refractoriness has been suggested to be a driver for the occurrence of AF paroxysms. Also, activation of intrinsic cardiac nerves prior to the onset of atrial fibrillation has been observed, possibly contributing to the development of AF, as may abnormal parasympathetic nerve outgrowth. Since the neural autonomic network is a hardware-based system compared to the neurohumoral system, strategies have been developed to eliminate pathologically increased sympathetic or parasympathetic tone via surgical or catheter ablation techniques of neuronal structures: left cardiac sympathetic denervation effectively reduces cardiac sympathetic tone and arrhythmia burden in patients with long QT syndrome. Likewise, transvascular renal sympathetic denervation can be applied to decrease systemic sympathetic tone and blood pressure in patients with resistant arterial hypertension. Selective ablation of intracardiac atrial parasympathetic plexus would be intriguing since it might increase atrial refractory periods without negatively affecting

Current and Emerging Indications for Implantable Cardiac Monitors

Implantable cardiac monitors (ICMs) continuously monitor the patient's electrocardiogram and perform real-time analysis of the heart rhythm, for up to 36 months. The current clinical use of ICMs involves the evaluation of transitory symptoms of possible arrhythmic origin, such as unexplained syncope and palpitations. Moreover, ICMs can also be used for the evaluation of difficult cases of epilepsy and unexplained falls, though current indications for their application in these sectors are less clearly defined. Finally, the ability of new-generation ICMs to automatically record arrhythmic episodes suggests that these devices could also be used to study asymptomatic arrhythmias, and thus could be proposed for the long-term evaluation of the total (symptomatic and asymptomatic) arrhythmic burden in patients at risk of arrhythmic events. In particular, ICMs may have an emerging role in the management of patients with atrial fibrillation and in those at risk of ventricular arrhythmias.

Long‐term Arrhythmia Variability after Monomorphic Ventricular Tachycardia in Patients with an Implantable Cardioverter Defibrillator

Arrhythmia burden in patients receiving an implantable cardioverter defibrillator (ICD) after monomorphic ventricular tachycardia (mVT) is higher than in patients with other indications. We investigated the long-term arrhythmia profile in this subset of patients. Fifty-two patients with an ICD implanted after mVT were followed up for at least 3 months. The cycle lengths (CLs) of the tachycardias recovered from the device memory were compared with the CL of the index arrhythmia. Morphological analysis of the intracardiac electrograms was performed and the response to antitachycardia pacing (ATP) was also assessed. A total of 833 mVT episodes with intracardiac electrograms occurred during the follow-up (3-58 months; mean: 30.3 months) in 41 of the 52 patients analyzed. mVTs with different CLs as compared with the index mVT were found in 26 (50.0%), and at least two different mVT morphologies were observed in 28 (53.8%) patients. Multiple mVT morphologies were predictive of lower ATP efficacy (95.6%, 85.0%, and 70.3% in the patients with 1, 2, and 3 or more mVT morphologies, respectively; P < 0.0001) and a higher shock burden (4.2%, 19.3%, and 24.7% in the patients with 1, 2, and 3 or more mVT morphologies, respectively; P < 0.0001). A high mVT burden was demonstrated with marked variability of the arrhythmias as concerns both CL and morphology in patients with an ICD implanted for mVT. Multiple mVT morphologies during the follow-up were predictive of lower ATP efficacy and a higher shock burden.

Do Statins Decrease the Arrhythmia Burden in Patients with Paroxysmal Atrial Fibrillation?

Do Statins Decrease the Arrhythmia Burden in Patients with Paroxysmal Atrial Fibrillation?

Effect of first ventricular tachycardia cycle length on rate of ventricular arrhythmia recurrence in patients with implantable cardioverter-defibrillator

Background Some controversies exist regarding the proper treatment of hemodynamically tolerated and slow ventricular tachycardia (VT). We intended to assess the effect of cycle length of first VT episode on total ventricular arrhythmia burden in a cohort of patients with implantable cardioverter-defibrillator (ICD). Method Between March 2000 and March 2005, 195 patients underwent ICD implantation at our center. We included 158 patients (mean age, 58.3 ± 12.9 years) with follow-up of 3 months or more in this study. Clinical, electrocardiographic, and ICD-stored data and electrograms were collected and analyzed. Results During the follow-up of 16.7 ± 10.6 months, 45 (28.5%) and 20 (12.6%) patients received first appropriate ICD therapy for VT and ventricular fibrillation, respectively. We divided the 45 patients with VT (based on the median value of VT cycle length) into 2 groups. Although patients with VT cycle length of less than 350 had higher total mean number of appropriate ICD therapy (25 vs 6.3, P = .023), during multivariate regression analysis, only left ventricular ejection fraction (EF) of less than 25% ( P = .020) was correlated with total number of appropriate ICD therapy. First VT cycle length ( P = .341), QRS duration ( P = .126), age ( P = .405), underlying heart disease ( P = .310), indication of ICD implantation ( P = .113), and sex ( P = .886) have failed to predict the total burden of ventricular arrhythmia during the follow-up period. Conclusion After adjustment for left ventricular EF, initial VT cycle length per se did not confer a lower risk for subsequent ventricular arrhythmia recurrence compared with those with faster VT. Left ventricular EF of less than 25% was correlated with higher ventricular arrhythmia burden in patients with ICD.

Biventricular pacing reduces ventricular arrhythmic burden and defibrillator therapies in patients with heart failure

Cardiac resynchronization therapy (CRT) has recently emerged as a new modality for the treatment of patients with advanced heart failure (HF). Cardiac resynchronization therapy reduces atrial and ventricular arrhythmia burdens. We analyzed the clinical data of patients who underwent an upgrade from a dual-chamber to a biventricular implantable cardioverter-defibrillator (ICD) at a tertiary care center. Nineteen patients (age 67 +/- 10 years, 18 men, left ventricular [LV] ejection fraction 0.24 +/- 0.07) underwent an upgrade to CRT-ICD. The LV lead was placed in a lateral position in 11, posterolateral in 4, and anterolateral in 3 patients. Baseline New York Heart Association class of HF improved in 11 (58%) patients who were considered "responders." After adjusting for the duration of follow-up before and after the upgrade, the number of patients receiving any ICD therapy decreased significantly from 13 to 4 (p = 0.004) and the total number of therapies decreased from 72 to 17 (p = 0.067). Also, the number of detections of sustained ventricular arrhythmias decreased from 40 to 11 episodes (p = 0.05), but the decrease in the number of detected supraventricular arrhythmias and mode switch episodes was not significant. The reduction in the ventricular arrhythmia load was independent of whether or not the patient responded to CRT. Our data suggest that CRT reduces ventricular but not atrial arrhythmia burden in patients with HF irrespective of their clinical response. This suggests that the reduction in arrhythmia is primarily an electrical phenomenon. Further studies are needed to confirm these findings and to uncover their underlying mechanisms.

Fixed overdrive pacing may decrease atrial arrhythmic burden in patients implanted with dual chamber pacemakers. The prove study

Fixed overdrive pacing may decrease atrial arrhythmic burden in patients implanted with dual chamber pacemakers. The prove study

Fixed overdrive pacing may decrease atrial arrhythmic burden in patients implanted with dual chamber pacemakers. The prove study

Fixed overdrive pacing may decrease atrial arrhythmic burden in patients implanted with dual chamber pacemakers. The prove study

Fixed overdrive pacing may decrease atrial arrhythmic burden in patients implanted with dual chamber pacemakers. The prove study

Fixed overdrive pacing may decrease atrial arrhythmic burden in patients implanted with dual chamber pacemakers. The prove study

Actions of sodium and potassium ions on baroreceptors of normotensive and spontaneously hypertensive rats.

Actions of sodium and potassium ions on baroreceptors of normotensive and spontaneously hypertensive rats.