Direct current cardioversion: indications, techniques, and recent advances

Pathophysiology and treatment of adults with arrhythmias in the emergency department, part 2: Ventricular and bradyarrhythmias

PURPOSE

This is the second article in a 2-part series reviewing the pathophysiology and treatment considerations for arrhythmias. Part 1 of the series discussed aspects related to treating atrial arrhythmias. Here in part 2, the pathophysiology of ventricular arrhythmias and bradyarrhythmias and current evidence on treatment approaches are reviewed.

SUMMARY

Ventricular arrhythmias can arise suddenly and are a common cause of sudden cardiac death. Several antiarrhythmics may be effective in management of ventricular arrhythmias, but there is robust evidence to support the use of only a few of these agents, and such evidence was largely derived from trials involving patients with out-of-hospital cardiac arrest. Bradyarrhythmias range from asymptomatic mild prolongation of nodal conduction to severe conduction delays and impending cardiac arrest. Vasopressors, chronotropes, and pacing strategies require careful attention and titration to minimize adverse effects and patient harm.

CONCLUSION

Ventricular arrhythmias and bradyarrhythmias can be consequential and require acute intervention. As experts in pharmacotherapy, acute care pharmacists can participate in providing high-level intervention by aiding in diagnostic workup and medication selection.

The Epidemiology and Effectiveness of Synchronized Cardioversion in a UK Prehospital Setting: A Retrospective Cross-Sectional Study

BACKGROUND

Synchronized cardioversion is an internationally accepted standard therapy for unstable tachyarrhythmias, but it is conventionally an in-hospital physician-led intervention. Increasingly, it is being brought forward into the prehospital setting as part of a specialist paramedic scope of practice; however, very little literature exists regarding the epidemiology or efficacy in this setting.

METHODS

All patients receiving cardioversion within a United Kingdom (UK) ambulance service were identified using an electronic database. The period of inclusion was March 1, 2017 through October 31, 2020. These data were then interrogated to provide demographic, physiological, and efficacy data, and then a sub-group was created to identify those who presented with a primary arrhythmia (as opposed to post-cardiac arrest).

RESULTS

From a total of 93 patients, prehospital synchronized cardioversion successfully terminated the tachyarrhythmia in 96% of patients presenting with a primary arrhythmia (85% in the allcomers group) with a predominance towards males (82% of patients) and an average age of 67 years. Hypotension and reduced level of consciousness were the most commonly documented unstable features (84.4% and 44.4%).

CONCLUSION

Cardioversion within a paramedic-led service results in efficacy rates of 96% in patients presenting with a primary tachyarrhythmia. This is a similar efficacy rate to traditional doctor-led therapies. Demographic data show that males make up over 80% of the patient population, in keeping with previously published work across the spectrum of cardiac interventions.

Effectiveness of dual external direct current cardioversion for initial cardioversion in atrial fibrillation

INTRODUCTION

Dual external direct current cardioversion (dual-DCCV) is a rhythm control strategy for persistent atrial fibrillation (AF), involving simultaneous delivery of two shocks from two defibrillators. The long-term effectiveness of this approach has not been studied in the biphasic cardioversion era.

METHODS

Seventy-seven consecutive patients at a single center were identified to receive dual-DCCV at the time of their initial cardioversion for AF, when maximum output standard external direct current cardioversion failed in two vectors. Logistic regression was used to analyze risk factors for dual-DCCV in a historical control group of 77 patients undergoing standard cardioversion and Cox proportional hazard models were used to compare time to AF recurrence.

RESULTS

The dual-DCCV group had a significantly larger body mass index (BMI), but similar AF duration and left atrial size as controls. Multivariable logistic regression revealed that BMI and absence of prior paroxysmal AF were risk factors for dual-DCCV (P < 0.05). There was no difference observed between dual-DCCV and control groups (adjusted hazard ratio = 0.57; P = .12) after adjusting for number of shocks and age. Transient hypoxia was the only acute complication in either group (P > .999).

CONCLUSION

Dual-DCCV appears to be a safe and effective cardioversion strategy for patients with AF. The need for dual-DCCV in the treatment of AF appears to be influenced more by body habitus than atrial substrate.

Initial evaluation and management of wide-complex tachycardia: A simplified and practical approach

The evaluation and treatment of wide QRS-complex tachycardia remains a challenge, and mismanagement is quite common. Diagnostic aids such as wide-complex tachycardia algorithms perform poorly in the real-life setting. The purpose of this review is to offer a simple clinical-electrocardiographic approach for the initial evaluation and management of the adult patient with stable wide-complex tachycardia that does not require recollection of complex guidelines or algorithms.

Current treatment options for atrial flutter and results with cryocatheter ablation

Rhythm disturbances arising in the upper chambers of the heart are not uncommon. They are associated with a heavy burden of illness for the affected individual, as well as society in general. Atrial flutter, a re-entrant atrial tachycardia, is one such rhythm disturbance. The objective of this review article is twofold: first, to provide a brief insight into atrial flutter and the typical treatments for this arrhythmia in clinical practice; and second, to give an in-depth account of cryocatheter ablation as a relatively new treatment option for this potentially debilitating condition. The many recent clinical studies documenting the use of cryocatheter ablation for treatment of atrial flutter are presented, and their results briefly discussed. Overall, as cryocatheter ablation embeds itself among the arsenal of treatments for atrial flutter, the promising results from clinical studies appear destined to elevate cryocatheter ablation to a premier position among the treatment options for atrial flutter.

Cutaneous remodeling and photorejuvenation using radiofrequency devices

Radio frequency (RF) is electromagnetic radiation in the frequency range of 3-300GHz. The primary effects of RF energy on living tissue are considered to be thermal. The goal of the new devices based on these frequency ranges is to heat specific layers of the skin. The directed use of RF can induce dermal heating and cause collagen degeneration. Wound healing mechanisms promote the remodeling of collagen and wound contraction, which ultimately clinically enhances the appearance of mild to moderate skin laxity. Preliminary studies have reported efficacy in the treatment of laxity that involves the periorbital area and jowls. Because RF energy is not dependent on specific chromophore interaction, epidermal melanin is not at risk of destruction and treatment of all skin types is possible. As such, radiofrequency-based systems have been used successfully for nonablative skin rejuvenation, atrophic scar revision and treatment of unwanted hair, vascular lesions and inflammatory acne. The use of RF is becoming more popular, although a misunderstanding exists regarding the mechanisms and limitations of its actions. This concise review serves as an introduction and guide to many aspects of RF in the non ablative rejuvenation of skin.

Significance of new-onset prolonged sinus tachycardia in a medical intensive care unit: a prospective observational study

OBJECTIVE

Few data are available on sinus tachycardia among medical intensive care unit (ICU) patients. We investigated new critical illnesses related to new-onset prolonged sinus tachycardia (NOPST) and the relationship of NOPST with ICU mortality.

METHODS

The heart rate (HR) of all enrolled patients was monitored hourly over a 12-month period, and NOPST was defined as sinus tachycardia (>100 beats/min) with an increase in HR of more than 20% from the baseline value lasting longer than 6 hours.

RESULTS

Among the 522 patients enrolled, the average mean HR was 96.1 ± 18.4 beats/min. Fifty-two (10.0%) patients met the criteria for NOPST; pneumonia, delirium, septic shock, acute respiratory distress syndrome, catheter-related infections, and mechanical ventilator-related problems were related to the occurrence of NOPST. The ICU mortality rate in patients with a NOPST duration of more than 72 hours was higher compared with other patients with NOPST (60.0% vs 18.5%; P = .002). A high daily mean HR rather than NOPST was a significant predictor of ICU mortality (odds ratio, 1.415; 95% confidence interval, 1.177-1.700).

CONCLUSIONS

Although NOPST was not associated with ICU mortality, it indicates the presence of new critical events in the medical ICU setting.

Electrical cardioversion

External electrical cardioversion was first performed in the 1950s. Urgent or elective cardioversions have specific advantages, such as termination of atrial and ventricular tachycardia and recovery of sinus rhythm. Electrical cardioversion is life-saving when applied in urgent circumstances. The succcess rate is increased by accurate tachycardia diagnosis, careful patient selection, adequate electrode (paddles) application, determination of the optimal energy and anesthesia levels, prevention of embolic events and arrythmia recurrence and airway conservation while minimizing possible complications. Potential complications include ventricular fibrillation due to general anesthesia or lack of synchronization between the direct current (DC) shock and the QRS complex, thromboembolus due to insufficient anticoagulant therapy, non-sustained VT, atrial arrhythmia, heart block, bradycardia, transient left bundle branch block, myocardial necrosis, myocardial dysfunction, transient hypotension, pulmonary edema and skin burn. Electrical cardioversion performed in patients with a pacemaker or an incompatible cardioverter defibrillator may lead to dysfunction, namely acute or chronic changes in the pacing or sensitivity threshold. Although this procedure appears fairly simple, serious consequences might occur if inappropriately perfformed.

Nonablative cutaneous remodeling using radiofrequency devices

In recent years, several new radiofrequency devices have been introduced for treatment of a variety of skin conditions, particularly, skin wrinkling and laxity. These nonsurgical systems induce tissue tightening and contour changes through dermal collagen remodeling without disruption of the overlying epidermis, obviating a significant recovery period or risk of serious adverse sequelae. As such, radiofrequency-based systems have been used successfully for nonablative skin rejuvenation, atrophic scar revision, and treatment of unwanted hair, vascular lesions, and inflammatory acne.

Atrial flutter: a focus on treatment options for a common supraventricular tachyarrhythmia

Atrial flutter (AFl), a re-entrant atrial tachycardia, is a cardiac rhythm disturbance that arises in the upper chambers of the heart. This usually non-life-threatening condition can be treated by a number of medical intervention strategies, which include electrical cardioversion, pharmacological therapy, and catheter ablation. These options have been available in clinical practice for a number of years. However, catheter ablation, in the form of radiofrequency catheter ablation and cryo catheter ablation, is increasingly utilised as a first-line treatment option for AFl in certain patients. The purpose of this review article is two-fold: first, to briefly present an overview of AFl and the more familiar treatment options for this arrhythmia, and second to provide more in-depth coverage of catheter ablation technologies as a treatment option for patients with AFl. As part of the latter objective, recent clinical studies documenting the use of radiofrequency catheter ablation and cryo catheter ablation for AFl are presented and their results briefly discussed.

Selective electro-thermolysis in aesthetic medicine: A review

The use of radiofrequency (RF) for selective electro-thermolysis has been found to produce a highly efficient thermal effect on biological tissue. Different from optical energy, RF energy is dependent on the electrical properties of the tissue rather than on concentration of chromophores in the skin for selective thermal destruction of targeted sites. Good results have been obtained with systems that use RF current alone for skin resurfacing, with efficacy comparable to laser resurfacing but with potentially more rapid healing. A related adverse effect is pain accompanying the procedure, due to a high depth of penetration. Another technology integrates RF energy together with optical energy (using lower energies of both forms of energies). These systems have shown efficacy in hair removal for all hair colors and skin types, as well as wrinkle reduction; and may reduce the risk of side effects associated with either RF or optical treatments alone. This article discusses the properties of electrical current in medicine and reviews the studies to date that have evaluated RF energy for dermatological applications.

Comparison of the efficacy and safety of two biphasic defibrillator waveforms for the conversion of atrial fibrillation to sinus rhythm

The overall efficacy of transthoracic biphasic shocks delivered for conversion of atrial fibrillation (AF) has been demonstrated. We compared 2 different energy waveforms, either the biphasic rectilinear (BRL) waveform or the biphasic truncated exponential (BTE) waveform, in the conversion of AF to sinus rhythm. The relation between energy required for the conversion of AF, the type of biphasic waveform, and patient characteristics were examined. Serum levels of cardiac troponin I were measured before and after cardioversion, as well as postprocedural skin erythema and discomfort. In this prospective trial, 101 patients (mean age 61 +/- 15 years, 72 men [71%]) referred for elective electrical cardioversion of AF were randomized to either a BTE or a BRL device. Shocks were delivered in a step-up fashion beginning with 50 J (then 100 J, 200 J, repeat 200 J, and then crossover to 360 J). One hundred patients were successfully converted to sinus rhythm (99% success rate). There was no difference in efficacy at any energy level used, regardless of the duration of the arrhythmia. In addition, there was no difference in cumulative success. Troponin I did not significantly increase after cardioversion, regardless of the total energy used. A positive correlation between skin erythema and skin discomfort after shock (24 to 48 hours) was seen with increasing cumulative energies. There was also a positive trend toward increasing energy requirements as chest circumference and body mass index increased. Thus, biphasic waveforms are safe and effective at converting AF to sinus rhythm. In this study population, there was no clinical difference between the BRL and the BTE waveforms.

Present treatment options for atrial fibrillation

Atrial fibrillation is the commonest sustained cardiac arrhythmia. It accounts for >35% of all hospital admissions for cardiac arrhythmias in the United States. The presence of atrial fibrillation increases the mortality of a population by up to twofold. The risk of stroke increases from 1.5% in patients with atrial fibrillation from 50-59 years of age to up to 23.5% for such patients aged 80-89 years. Although the diagnosis of atrial fibrillation is usually straightforward, effective treatment is not. This article will discuss how rhythm control of atrial fibrillation can best be achieved, the controversy over the rhythm versus rate control, the maintenance of sinus rhythm with antiarrhythmic drugs after cardioversion, and prevention of thromboembolism. Finally, the recent advances in various non-pharmacological approaches for the treatment of atrial fibrillation will be highlighted.