Optimizing therapy for heart failure patients: cardiac resynchronization and defibrillator therapy

Heart failure continues to be diagnosed at unprecedented rates. It is essential that the affiliated professional, including the nurse practitioner, clinical nurse specialist, and physician assistant, be aware of the current treatments and technology that improve symptoms and reduce mortality rates in patients with heart failure. Medications remain critical in reducing symptoms. New clinical trial data on cardiac resynchronization therapy and cardiac resynchronization therapy with defibrillation reveal improved mortality and quality of life in patients already on optimal drug therapy. This article addresses current treatment strategies with drugs and devices, summarizes therapy efficacy based on clinical trial data, and provides a case study illustrating a typical patient who could benefit from the addition of device therapy. Through awareness of current guidelines and advocacy for the patient, nurses and affiliated professionals have an essential role in reducing mortality and improving outcomes for heart failure patients.     

Reducing mortality with device therapy in heart failure patients without ventricular arrhythmias

Use of device therapy to prevent sudden cardiac death in patients with heart failure is expanding on the basis of evidence from recent clinical trials. Three multicenter prospective clinical trials-Sudden Cardiac Death in Heart Failure (SCD-HeFT); Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure (COMPANION); and Cardiac Resynchronization-Heart Failure (CARE-HF)-were conducted to determine the effectiveness of devices in reducing mortality in patients with heart failure who did not have a history of ventricular arrhythmias. The 3 trials varied in the devices used, the population of patients included, and the study designs. In SCD-HeFT, implantable cardioverter defibrillators were more effective than pharmacological therapy in preventing mortality among patients with mild to moderate heart failure. In COMPANION, cardiac resynchronization therapy alone and cardiac resynchronization therapy plus an implantable cardioverter defibrillator were more effective than optimal drug treatment in reducing morbidity and all-cause mortality in patients with moderate to severe heart failure. In CARE-HF, cardiac resynchronization therapy alone was more effective than optimal drug treatment in reducing all-cause mortality in patients with moderate to severe heart failure. No direct comparison of the devices used has been done. These 3 clinical trials provide clear evidence that device therapy is beneficial for some patients with heart failure, even patients who do not have a history of ventricular arrhythmia.     

Cardiac resynchronization therapy for congestive heart failure

Cardiac resynchronization represents a novel therapeutic strategy for the treatment of congestive heart failure due to systolic dysfunction. Since its modest beginnings in the 1990s, cardiac resynchronization therapy has gained widespread acceptance as a useful adjunct to pharmacologic therapy for congestive heart failure. Randomized trials have consistently shown functional improvement in patients with congestive heart failure due to systolic dysfunction, a wide QRS complex on electrocardiogram and sinus rhythm, that are treated with cardiac resynchronization therapy. This review article will address the rationale, mechanisms of action, limitations and appropriate selection of patients for cardiac resynchronization therapy.     

Device therapy for the management of advanced heart failure

Rapid advances have been made over the last decade in the nonpharmacological treatment of patients with advanced heart failure. This article reviews the current application of device therapy including cardiac resynchronization, defibrillators, cardiac restraint devices and mechanical ventricular support in patients with advanced heart failure.     

Device therapy for the management of advanced heart failure

Rapid advances have been made over the last decade in the nonpharmacological treatment of patients with advanced heart failure. This article reviews the current application of device therapy including cardiac resynchronization, defibrillators, cardiac restraint devices and mechanical ventricular support in patients with advanced heart failure.     

AV junctional ablation allowing more effective delivery of cardiac resynchronization therapy in patients with intra- and interatrial conduction delay

We report two patients with cardiac resynchronization therapy (CRT) devices and evidence of refractory heart failure in whom impaired intraatrial conduction in one patient, and interatrial conduction in the other, prohibited optimization of the atrioventricular (AV) timing sequence. The patient with intraatrial conduction delay exhibited late right atrial sensing and latency during right atrial pacing that required programming of a short-sensed AV delay and long-paced AV delay (wide differential AV delay). In both patients AV junctional ablation and echocardiography-guided device optimization significantly improved heart failure.     

Using devices for physiologic monitoring in heart failure

Heart failure (HF) is a complex and costly disease process associated with high morbidity and mortality. Implanted cardiac rhythm management devices are increasingly used in the HF population to provide therapies such as protection from sudden death and cardiac resynchronization therapy. Device-based diagnostic monitoring provides clinicians with information that can assist in identifying patients at risk for HF decompensation and subsequent hospitalization. This article will review the evidence for using diagnostic information from cardiac rhythm management devices in the management of HF patients. Future advanced monitoring devices will also be discussed.     

Living with cardiac resynchronization therapy: Challenges for people with heart failure

The number of people with heart failure requiring implantation of a cardiac resynchronization device is increasing in Iran. Although this intervention is an effective life‐saving treatment, several challenges are associated with patients’ lifestyle after insertion. This study identified the challenges and coping mechanisms of Iranians with heart failure living with cardiac resynchronization therapy. A qualitative approach using conventional content analysis was adopted. Seventeen people with heart failure and three nurses were recruited between December 2014 and November 2015 from a teaching hospital and a private clinic in Rasht, Iran. Participants were interviewed using semi‐structured interviews lasting 30–60 min. Five themes emerged: (i) fear of implantation, (ii) the panic of receiving a shock from the device, (iii) lack of control over life, (iv) inadequacies of the healthcare system, and (v) psychosocial coping. A heightened understanding of these challenges and coping strategies could prepare healthcare professionals to provide better routine care, education, and support to the recipients of cardiac resynchronization therapy prior to implantation, during the recovery period, and for long‐term management.     

Left Ventricular Mechanical Assist Devices and Cardiac Device Interactions: An Observational Case Series

Background: Nonpulsatile left ventricular assist devices (LVADs) are increasingly used for treatment of refractory heart failure. A majority of such patients have implanted cardiac devices, namely implantable cardioverter-defibrillators (ICDs) or cardiac resynchronization therapy-pacemaker (CRT-P) or cardiac resynchronization therapy-defibrillator (CRT-D) devices. However, potential interactions between LVADs and cardiac devices in this category of patients remain unknown.
Methods: We reviewed case records and device logs of 15 patients with ICDs or CRT-P or CRT-D devices who subsequently had implantation of a VentrAssist LVAD (Ventracor Ltd., Chatswood, Australia) as destination therapy or bridge to heart transplantation. Pacemaker and ICD lead parameters before and after LVAD implant were compared. In addition, ventricular tachyarrhythmia event logs and potential electromagnetic interference reports were evaluated.
Results: Right ventricular (RV) sensing decreased in the first 6 months post-LVAD. Mean R-wave amplitude preimplant was 10.9 ± 5.25 mV compared with 7.2 ± 3.4 mV during follow-up (P = 0.02). RV impedance also decreased from 642 ± 240 ohms at baseline to 580 ± 212 ohms at follow-up (P = 0.007). There was a significant increase in RV stimulation threshold following implantation of the LVAD from 0.8 ± 0.6 V at baseline to 1.4 ± 1.0 V in the first 6 months postimplant (P = 0.01). A marked increase in ventricular tachyarrhythmia burden was observed in three patients. One patient displayed electromagnetic interference between the LVAD and defibrillator, resulting in inappropriate defibrillation therapy.
Conclusions: LVADs have a definite impact on cardiac devices in respect with alteration of lead parameters, ventricular tachyarrhythmias, and electromagnetic interference.     

Economic analysis of a randomized trial of biventricular pacing in Canada

BACKGROUND: Congestive heart failure (CHF) has been shown to affect 5% of the Canadian adult population, and leads to 9.5 deaths per 100 cardiac-related hospitalizations in Canada. The economic outcomes from biventricular pacing for heart failure are not well understood. This study analyzes resource utilization and related costs associated with CHF for patients who receive standard implantable cardiac defibrillators (ICDs) versus those who receive ICD plus biventricular pacing or cardiac resynchronization therapy (CRT). METHODS: The Canadian analysis of resynchronization therapy in heart failure (CART-HF) study included 72 patients with New York Heart Association class II-IV CHF requiring an ICD. Patients were randomized to receive either ICD + CRT treatment or ICD treatment alone. Medical resource utilization data were collected for 6 months following treatment and were applied to representative costs for the provinces of Quebec and Ontario. Resource utilization was subcategorized into pharmacological therapy, physician visits, hospitalizations, adverse events, and productivity losses. RESULTS: Post-treatment, per patient costs for the CRT + ICD treatment group were less than the follow-up costs for patients receiving ICD treatment only in each province. Mean savings for patients receiving biventricular therapy were CAD 2,420 dollars in Quebec and CAD 2,085 dollars in Ontario during the 6-month follow-up. CONCLUSIONS: These analyses indicate that savings in post-implant health-care utilization (hospitalizations and pharmacological therapy) can offset some of the device and procedural costs associated with CRT devices.     

Drug and drug-device therapy in heart failure patients in the post-COMET and SCD-HeFT era

Reduced left ventricular ejection fraction and heart failure are the most important risk factors for sudden cardiac death. Recent trials have contributed to the knowledge base of critical therapies for the treatment of left ventricular systolic dysfunction and heart failure as it relates to arrhythmic and sudden cardiac death. Both pharmacologic and device therapies can reduce sudden cardiac death. The trials discussed in this paper have identified the pharmacologic and device interventions that are likely to improve the length and quality of life of the patient with left ventricular dysfunction and reduce the risk of sudden cardiac death. The mortality and anti-arrhythmic effects of angiotensin-converting enzyme inhibitors and beta-blockers have been confirmed in large-scale controlled clinical heart failure trials. Recent trials have evaluated which agents are most effective and which patients will derive the most benefit from device therapy in terms of the reduction in the risk of sudden cardiac death and in the amelioration of heart failure. The recent data from the Carvedilol or Metoprolol European Trial (COMET) and the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT) are discussed as the latest in the series of landmark studies that have shaped the current approaches to treating patients with heart failure and that have altered the heart failure treatment paradigm.     

Cardiac resynchronization therapy and automatic implantable cardiac defibrillators in the treatment of heart failure: a review article

PURPOSE: To review the use of cardiac resynchronization therapy (CRT) and automatic implantable cardiac defibrillators (AICDs) in heart failure (HF) patients. DATA SOURCES: Selected scientific literature. CONCLUSIONS: New developments in device therapy for HF patients are helping to decrease morbidity and mortality in this challenging patient population. CRT improves left ventricular (LV) ejection fraction, quality of life, 6-min walk distances, and New York Heart Association scores in select patients. AICDs can prevent sudden cardiac death in those who have LV dysfunction and are at risk for ventricular arrhythmias. Cardiac devices are now becoming a standard of care for those with HF who meet certain criteria. IMPLICATIONS FOR PRACTICE: Despite advances in medical therapy for treating LV dysfunction, newly diagnosed patients face a 50% mortality rate in 5 years. The natural history of HF leads to continual deterioration of function unless adverse cardiac remodeling is reversed. Until recently, the only means for improving symptoms and cardiac function has been through the optimization of standard medicines that are indicated for LV dysfunction, such as angiotensin-converting enzyme inhibitors and beta-blockers. However, not all patients benefit from medical management alone. Cardiac devices may now be considered when significant symptoms persist after standard medicines are optimized. When practitioners use a multiple-modality approach, careful patient selection based on the inclusion criteria used in the trials outlined in this article will likely lead to improved management of those with LV dysfunction.     

Cardiac defibrillation and resynchronization therapies: principles, therapies, and management implications

Patients with heart failure remain at high risk for sudden cardiac death (SCD) and death due to heart failure progression, despite the incorporation of pharmacologic agents into clinical practice that have been shown to decrease mortality in clinical trials. Most patients experience SCD as their first dysrrhythmic event. The implantable cardioverter defibrillator (ICD) effectively terminates ventricular tachycardia/fibrillation (VT/VF) aborting SCD. Cardiac resynchronization therapy (CRT) complements pharmacologic therapy improving cardiac performance, quality of life, functional status, and exercise capacity in patients with systolic dysfunction despite optimal medical therapy who have a prolonged QRS duration; furthermore, it decreases mortality when compared with optimal medical therapy alone. Implantation of a combination CRT and ICD device, a CRT-D, reduces mortality by aborting SCD and providing the functional benefits of CRT. This article discusses the evolution of CRT-D therapy, the mechanism of operation of a CRT-D device, and nursing implications.     

Cardiac transplantation: candidate identification, evaluation, and management

For more than 40 years, cardiac transplantation has been a treatment option for patients with severe heart failure in whom optimal medical management is no longer effective. Critical care nurses are integrally involved in the care of patients with severe heart failure who may benefit from cardiac transplantation and are in a special position to recognize potential candidates for transplantation. Understanding patient selection criteria, the evaluation process, and how patients are managed while awaiting transplantation is key to the knowledge and skills required. It is also important to understand the allocation of donor hearts as part of this process. The waiting period for a suitable donor heart can be long and a patient's condition may deteriorate, requiring an increase in pharmacologic bridges with intravenous inotropic agents or mechanical bridges with circulatory assist devices. Critical care nurses become important as a personal bridge to transplantation through their education of patients and families and helping them cope with their fears during the waiting period. Critical care nurses who possess knowledge of patient selection and organ allocation processes along with the skills of caring for this complex patient population can contribute to better outcomes for patients with heart failure who may be candidates for cardiac transplantation.     

Contemporary management of pediatric heart failure

The spectrum of causes of pediatric heart failure is broad and differs significantly from that seen in most adult patients. Left-to-right shunts and outflow obstruction lesions are responsible for a large number of pediatric cases of heart failure. Most of these are now treated successfully with surgery or catheter intervention. Medical therapy is the mainstay of care for myocardial disorders with diuretics, angiotensin-converting enzyme inhibitors, beta-blockade and cardiac glycosides. There are few prospective trials of these agents in a pediatric population, but extrapolated data support their use in children. In addition to medical therapy, interventions such as automatic implantable cardioverter defibrillators and resynchronization therapy have become increasingly common in pediatric heart disease, as well as in adult patients with congenital heart disease.     

Cardiogenic shock: treatment

The treatment of cardiogenic shock complicating the acute coronary syndromes consists of medical therapy, percutaneous revascularization procedures, cardiac surgery, and the implantation of devices. Medical therapy is limited to different positive inotropic and vasoactive drugs, without any firm evidence of survival benefit using these drugs. Several new pharmacologic compounds are at different stages of clinical research, but are not yet routinely approved for the treatment of cardiogenic shock. The only evidence-based therapy with proven survival benefit is timely revascularization. Intra-aortic balloon pump counterpulsation maintains its central role as supportive treatment in cardiogenic shock patients. Anecdotal evidence is available about the use of ventricular assist devices, cardiac resynchronization therapy, and emergent heart transplantation.     

Quality of death: implantable cardioverter defibrillators and proactive care

OBJECTIVES: The purpose of this paper is to discuss quality of death (QOD) among patients with congestive heart failure (CHF) and implantable cardioverter defibrillators. We outline recommendations that enhance QOD from the device patient and specialty cardiology perspectives. BACKGROUND: Contemporary treatment of CHF patients routinely includes both pharmacologic therapy and the use of cardiac devices. The implantable cardioverter defibrillator prevents premature death in heart failure patients, though not death itself. CONCLUSIONS: Active discussion and consideration of patient's QOD is indicated in implantable cardioverter defibrillator patients to prevent unnecessary treatment and to increase control over perceived quality of life by patients and family.     

Imaging techniques in cardiac resynchronization therapy

Cardiac resynchronization therapy is a high cost therapeutic option with proven efficacy on improving symptoms of ventricular failure and for reducing both hospitalization and mortality. However, a significant number of patients do not respond to cardiac resynchronization therapy that is due to various reasons. Identification of the optimal pacing site is crucial to obtain the best therapeutic result that necessitates careful patient selection. Currently, using echocardiography for mechanical dyssynchrony assessment performs patient selection. Multi-Detector-Row Computed Tomography (MDCT) and Magnetic Resonance Imaging (MRI) are new imaging techniques that may assist the cardiologist in patient selection. These new imaging techniques have the potential to improve the success rate of cardiac resynchronization therapy, due to pre-interventional evaluation of the venous coronary anatomy, to evaluation of the presence of scar tissue, and to improved evaluation of mechanical dyssynchrony. In conclusion, clinical issues associated with heart failure in potential candidates for cardiac resynchronization therapy, and the information regarding this therapy that can be provided by the imaging techniques echocardiography, MDCT, and MRI, are reviewed.     

超声心动图评价心脏再同步化治疗疗效

目的探讨超声心动图在慢性充血性心力衰竭患者心脏再同步化治疗疗效评价中的应用价值。方法 27例接受心脏再同步化治疗的慢性充血性心力衰竭患者,分别于术前及术后6个月应用超声心动图测量左心室大小、左心室容积、左心室射血分数、二尖瓣反流面积、房室间、心室间及左心室内同步性。结果术后6个月患者左心室收缩末内径、左心室舒张末内径、左心室收缩末容积、左心室舒张末容积小于术前（P〈0.05或P〈0.01）,房室间、心室间、左心室内收缩同步性改善（P〈0.05或P〈0.01）。结论超声心动图可通过多项参数综合评价心脏再同步化治疗的效果。     

Assessing Acute Ventricular Volume Changes by Intracardiac Impedance in a Chronic Heart Failure Animal Model

Background: Implantable device diagnostics may play an essential role in simplifying the care of heart failure patients by providing fundamental insights into their complex clinical patterns. Early recognition of heart failure progression by a continuous hemodynamic monitoring would allow for timely therapeutic interventions to prevent decompensation and hospitalization. In this study, the feasibility of assessing ventricular volume changes by implant-based measurements of intracardiac impedance was tested in a heart failure animal model.
Methods: Heart failure was induced in five minipigs by high-rate pacing over 3 weeks. During a final open-chest examination a graded dobutamine stress test was performed. Stroke volume (SV) was measured by an ultrasonic flow probe at the ascending aorta. End diastolic pressure (EDP) and maximum pressure slope (dP/dt_max) were calculated from a left ventricular microtip catheter signal. Impedance was measured by an implanted pacemaker between biventricular leads. Stroke impedance (SZ) was calculated as the difference between end-systolic and end-diastolic impedance (EDZ).
Results: Administration of dobutamine led to an increase in SV (55 ± 16%), dP/dt_max (107 ± 89%), and SZ (56 ± 30%). EDP changed by 37 ± 21% whereas EDZ changed by 7.4 ± 4%. Significant correlations were found between SZ and SV (r = 0.88), and between EDZ and EDP (r =−0.82).
Conclusion: The strong correlation with SV allows the application of intracardiac impedance measurements for an implant-based continuous monitoring of cardiac function. Impedance may also be used for hemodynamic optimization of cardiac resynchronization therapy.