Heart Failure Devices

New Era of Electroceuticals: Clinically Driven Smart Implantable Electronic Devices Moving towards Precision Therapy

In the name of electroceuticals, bioelectronic devices have transformed and become essential for dealing with all physiological responses. This significant advancement is attributable to its interdisciplinary nature from engineering and sciences and also the progress in micro and nanotechnologies. Undoubtedly, in the future, bioelectronics would lead in such a way that diagnosing and treating patients' diseases is more efficient. In this context, we have reviewed the current advancement of implantable medical electronics (electroceuticals) with their immense potential advantages. Specifically, the article discusses pacemakers, neural stimulation, artificial retinae, and vagus nerve stimulation, their micro/nanoscale features, and material aspects as value addition. Over the past years, most researchers have only focused on the electroceuticals metamorphically transforming from a concept to a device stage to positively impact the therapeutic outcomes. Herein, the article discusses the smart implants' development challenges and opportunities, electromagnetic field effects, and their potential consequences, which will be useful for developing a reliable and qualified smart electroceutical implant for targeted clinical use. Finally, this review article highlights the importance of wirelessly supplying the necessary power and wirelessly triggering functional electronic circuits with ultra-low power consumption and multi-functional advantages such as monitoring and treating the disease in real-time.

Shedding Light on the Black Box: Explaining Deep Neural Network Prediction of Clinical Outcomes

Deep neural network models are emerging as an important method in healthcare delivery, following the recent success in other domains such as image recognition. Due to the multiple non-linear inner transformations, deep neural networks are viewed by many as black boxes. For practical use, deep learning models require explanations that are intuitive to clinicians. In this study, we developed a deep neural network model to predict outcomes following major cardiovascular procedures, using temporal image representation of past medical history as input. We created a novel explanation for the prediction of the model by defining impact scores that associate clinical observations with the outcome. For comparison, a logistic regression model was fitted to the same dataset. We compared the impact scores and log odds ratios by calculating three types of correlations, which provided a partial validation of the impact scores. The deep neural network model achieved an area under the receiver operating characteristics curve (AUC) of 0.787, compared to 0.746 for the logistic regression model. Moderate correlations were found between the impact scores and the log odds ratios. Impact scores generated by the explanation algorithm has the potential to shed light on the "black box" deep neural network model and could facilitate its adoption by clinicians.

Anesthetic Management of Laser Lead Extraction for Cardiovascular Implantable Electronic Devices

Cardiovascular implantable electronic devices (CIEDs) play a significant role in the modern management of cardiovascular disease. CIEDs include implantable pacemakers (PMs), implantable cardioverter-defibrillators (ICDs), and cardiac resynchronization therapy (CRT) devices. These devices improve the quality of life of their recipients and help reduce the incidence of sudden cardiac death. Traditionally, CIEDs have been reliant on the use of transvenous endocardial leads to directly connect with the heart. Over time, these endovascular leads may become endothelialized rendering removal extremely difficult. As the indications for CIEDs expands and with the continuing evolution of these devices, the number of patients requiring explantation for device recall, malfunction, and infection continues to increase. In this manuscript, we review the most common CIEDs, the indications and process of lead removal/device explantation, potential complications associated with the procedure and the anesthetic management of these patients.

Clinical Course After Cardioverter-Defibrillator Implantation: Chagasic Versus Ischemic Patients

Background:

The outcome of Chagas disease patients after receiving implantable cardioverter defibrillator (ICD) is still controversial.

Objective:

To compare clinical outcomes after ICD implantation in patients with chronic Chagas cardiomyopathy (CCC) and ischemic heart disease (IHD).

Methods:

Prospective study of a population of 153 patients receiving ICD (65 with CCC and 88 with IHD). The devices were implanted between 2003 and 2011. Survival rates and event-free survival were compared.

Results:

The groups were similar regarding sex, functional class and ejection fraction. Ischemic patients were, on average, 10 years older than CCC patients (p < 0.05). Patients with CCC had lower schooling and monthly income than IHD patients (p < 0.05). The number of appropriate therapies was 2.07 higher in CCC patients, who had a greater incidence of appropriate shock (p < 0.05). Annual mortality rate and electrical storm incidence were similar in both groups. There was no sudden death in CCC patients, and only one in IHD patients. Neither survival time (p = 0.720) nor event-free survival (p = 0.143) significantly differed between the groups.

Conclusion:

CCC doubles the risk of receiving appropriate therapies as compared to IHD, showing the greater complexity of arrhythmias in Chagas patients.

Ranolazine preserves and improves left ventricular ejection fraction and autonomic measures when added to guideline-driven therapy in chronic heart failure

Background

Ranolazine (RAN) reduces cardiac sodium channel 1.5’s late sodium current in congestive heart failure (CHF), reducing myocardial calcium overload, potentially improving left ventricular (LV) function. RAN blocks neuronal sodium channel 1.7, potentially altering parasympathetic and sympathetic (P&S) activity. The effects of RAN on LV ejection fraction (LVEF) and P&S function in CHF were studied.

Methods

Matched CHF patients were given open-label RAN (1000 mg po-bid) added to guideline-driven therapy (RANCHF, 41 systolic, 13 diastolic) or no adjuvant therapy (control, NORANCHF, 43 systolic, 12 diastolic). Echocardiographic LVEF and P&S measures were obtained at baseline and follow-up (mean 23.7 months).

Results

LVEF increased in 70% of RANCHF patients, an average of 11.3 units. Mean LVEF remained unchanged in NORANCHF patients. P&S measures indicated cardiovascular autonomic neuropathy (P≤0.1 bpm²) in 20% of NORANCHF patients at baseline and in 29% at follow-up (increasing in both groups). At baseline, 28% of patients had high sympathovagal balance (SB), RAN normalized SB over 50% of these; in contrast, the NORANCHF group had a 20% increase in patients with high SB.

Conclusions

RAN preserves or improves LVEF and decreases high SB in CHF.

Radiography of pacemakers and implantable cardioverter defibrillators

OBJECTIVE

The purpose of this article is to review the normal and abnormal radiographic appearances of cardiac pacemaker and implantable cardioverter defibrillator systems.

CONCLUSION

Chest radiographs showing pacemakers and implantable cardioverter defibrillators contain identifying and clinically relevant information, such as MRI compatibility and possible malfunction. Accurate and timely reporting of these features provides important information that can improve patient care.

Variation in use of dual-chamber implantable cardioverter-defibrillators: results from the national cardiovascular data registry

BACKGROUND

Among patients without an indication for a pacemaker, current evidence is inconclusive whether a dual-chamber implantable cardioverter-defibrillator (ICD) is superior to a single-chamber ICD. The current use of dual-chamber ICDs is not well characterized.

METHODS

We conducted a cross-sectional study exploring hospital-level variation in the use of dual-chamber ICDs across the United States. Patients receiving a primary prevention ICD from 2006 through 2009 without a documented indication for a pacemaker were included. Multivariate hierarchical logistic regression was used to explore patient, health care provider, and physician factors related to the use of a dual-chamber device.

RESULTS

Dual-chamber devices were implanted in 58% of the 87,115 patients without a pacing indication among 1293 hospitals, with hospital rates ranging from 0% in 33 centers to 100% in 109 centers. In multivariate analysis, geographic region was a strong independent predictor of dual-chamber device use, ranging from 36.4% in New England (reference region) to 66.4% in the Pacific region (odds ratio [OR], 5.25; 95% CI, 3.35-8.21). Hospital clustering was assessed using a median OR which was 3.96, meaning that 2 identical patients at different hospitals would have nearly a 4-fold difference in their chance of receiving a dual-chamber ICD.

CONCLUSIONS

Use of dual-chamber ICDs for the primary prevention of sudden cardiac death among patients without an indication for permanent pacing varies markedly at the hospital level in the United States. This is a clear example of how practice can vary independent of patient factors.

Indications for implantable cardioverter-defibrillator placement in ischemic cardiomyopathy and after myocardial infarction

Dramatic reductions in the rate of sudden cardiac death due to use of implantable cardioverter-defibrillators (ICDs) have been well-established in several large randomized clinical trials including patients with left ventricular dysfunction after myocardial infarction. This article reviews the literature regarding ICD utilization in the postinfarction population, with a strong emphasis on recent clinical trials. The most current indications for, and timing of, ICD implantation postinfarction also are summarized.

Contrast-enhanced whole-heart coronary MRA at 3.0T for the evaluation of cardiac venous anatomy

This study was designed to evaluate the value of contrast-enhanced whole-heart coronary MRA (CMRA) at 3.0T in depicting the cardiac venous anatomy. In cardiac resynchronization therapy (CRT), left ventricular (LV) pacing is achieved by positioning the LV lead in one of the tributaries of the coronary sinus (CS). Pre-implantation knowledge of the venous anatomy may help determine whether transvenous LV lead placement for CRT is feasible. Images of 51 subjects undergoing contrast-enhanced whole-heart CMRA at 3.0T were retrospectively analyzed. Data acquisition was performed using electrocardiography-triggered, navigator-gated, inversion-recovery prepared, segmented gradient-echo sequence. A 32-element cardiac coil was used for data acquisition. The visibility of the cardiac veins was graded visually using a 4-point scale (1: poor–4: excellent). The paired Student t test was used to evaluate differences in diameters of the ostium of the CS in anteroposterior and superoinferior direction. The cardiac veins were finally evaluated in 48 subjects with three anatomic variations. The diameter of the CS ostium in the superoinferior direction (1.13 ± 0.26 cm) was larger than in the anteroposterior direction (0.82 ± 0.19 cm) (P < 0.05). The mean visibility score of CS, posterior interventricular vein, posterior vein of the left ventricle, left marginal vein, and anterior interventricular vein was 4.0 ± 0.0, 3.4 ± 0.5, 3.4 ± 0.5, 3.0 ± 0.8, and 3.3 ± 0.5, respectively. In conclusion, contrast-enhanced whole-heart CMRA at 3.0T can depict the normal and variant cardiac venous anatomy.

Comparison of medical therapy dosing in outpatients cared for in cardiology practices with heart failure and reduced ejection fraction with and without device therapy: report from IMPROVE HF

BACKGROUND

Few data exist to characterize the delivery of evidence-based medical therapy for outpatients with heart failure who have received implantable cardioverter-defibrillators or cardiac resynchronization therapy (CRT) for systolic dysfunction.

METHODS AND RESULTS

IMPROVE HF is a prospective study characterizing the management of 15 381 outpatients with systolic heart failure (left ventricular ejection fraction ≤35%) enrolled from 167 US cardiology practices. Data were abstracted for dose, type, and daily frequency for angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, β-blockers, and aldosterone antagonists. Target doses for each medication class were based on current guidelines. Patients with devices (implantable cardioverter-defibrillators, CRT with defibrillators, or CRT with pacemakers) more frequently received evidence-based medical therapy than did those without such devices, although treatment at or above target doses was low for angiotensin-converting enzyme inhibitors/angiotensin receptor blockers (implantable cardioverter-defibrillators 32.6%, CRT with pacemaker 30.7%, CRT with defibrillator 32.0%, no device 34.6%) and β-blockers (20.2%, 17.4%, 20.4%, and 15.3%, respectively). Fewer patients received aldosterone antagonists, although when used, doses were more frequently within the target dosing range (70.1%, 72.1%, 72.7%, and 76.5%, respectively). Multivariable models showed that use of CRT with defibrillators and CRT with pacemakers was significantly associated with delivery of β-blockers at or above target doses, but no device therapies were associated with angiotensin-converting enzyme inhibitor/angiotensin receptor blocker or aldosterone antagonist dosing.

CONCLUSIONS

Patients treated with heart failure devices received evidence-based medical therapy at similar or greater frequency than did those without such devices. Patients with CRT with defibrillator or CRT with pacemaker devices were more likely to be treated with target doses of β-blockers than were patients not treated with device therapy. Doses of evidenced-based therapies remain significantly lower in clinical practice than in clinical trials.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00303979.

Primary ICD-therapy in patients with advanced heart failure: selection strategies and future trials

BACKGROUND

For allocation of primary ICD-therapy, a possible lower limit of inclusion criteria--defining overly advanced heart failure--is less well investigated. Also, a multi-variable approach to stratification beyond ejection fraction (LVEF) appears warranted. We examined whether adding a selection limit of peak VO(2) <or= 14 ml/kg/min to LVEF <or= 20% improves stratification. Furthermore, we sought to provide current survival data and a size-estimate for prospective trials based on real-life data for this high risk cohort.

METHODS

In our prospective clinical registry 1,926 patients with systolic CHF were recruited consecutively since 1994. Of these patients, 292 met the selection criteria described above. The mean age was 57.6 +/- 9.5 years, 83% were male, 37% had ischemic cardiomyopathy and 28% received primary ICD-therapy. All cause mortality was considered as end point.

RESULTS

Median follow-up was 45 (18-86) months. ICD was not a significant predictor of outcome either for the entire population, or grouped according to aetiology of CHF. Still, 3-year mortality was 15% (ICD-patients) Vs. 28% (non-ICD-patients); P = 0.05; under combination medical therapy. Inversely, in ICD-patients medical combination therapy conveyed a significant survival benefit (P < 0.001). Consequently, the number-needed-to-treat was eight under combination therapy and the size estimate amounts to 300 patients for a prospective trial in this cohort.

CONCLUSION

A cut-off of LVEF <or= 20% and pVO(2) <or= 14 ml/kg/min could identify patients that do not draw a significant survival benefit from adjunct primary ICD-therapy. Our results indicate the need for a specific randomized trial in this cohort. The according mortality data and a size estimate are provided.

Biventricular pacing and defibrillator use in chronic heart failure

Since the 1970s when the implantable cardioverter defibrillator (ICD) was developed, multiple clinical trials have documented survival benefits in certain high-risk subsets of heart failure patients. Over the past decade, cardiac resynchronization therapy (CRT) emerged as an important therapy in carefully selected patients with ongoing symptoms despite optimized pharmacological therapy. ICDs should be considered first-line therapy for survivors of life-threatening ventricular arrhythmic events. Subsets of patients with both ischemic and nonischemic dilated cardiomyopathy appear to have a survival benefit from primary ICD therapy. CRT has resulted in substantial symptomatic improvement and survival benefits in a subgroup of chronic heart failure patients. CRT should be considered in heart failure patients undergoing ICD implantation who have evidence of ventricular dyssynchrony.

Imaging of the coronary venous system: Retrograde coronary sinus angiography versus venous phase coronary angiograms

BACKGROUND

Left ventricular lead implantation for cardiac resynchronization therapy (CRT) usually requires a pre- or intraprocedural occlusion contrast venography of the coronary sinus (CS) in order to identify tributaries to the lateral wall. As many patients undergo a preprocedural coronary angiogram, we investigated the diagnostic accuracy of venous phase imaging of the CS in patients prior to CRT implantation. The aim of this study was to assess the quality of venous phase coronary sinus angiography.

METHODS

In 24 CRT patients retrograde occlusion venography and venous phase coronary sinus angiography obtained during coronary angiography were compared with respect to image quality, vessel diameters and the ability to identify a coronary sinus side branch suitable for left ventricular lead placement.

RESULTS

Suitable target vessels for left ventricular lead implantation were identified in all patients irrespective of the method (retrograde occlusion venography or venous phase coronary sinus angiography). There was a high concordance in vessel diameters between venous phase and retrograde angiography. Visibility was superior in retrograde venography.

CONCLUSIONS

In heart failure patients who are scheduled for coronary angiograms venous phase coronary sinus angiography is a time-saving and easy to perform alternative imaging modality. Radiation exposure and the amount of contrast medium needed is reduced as compared to coronary sinus occlusion angiography. The information obtained thereby may be used to plan subsequent CRT implantation without the need for retrograde coronary sinus angiography.

Development of device therapy for ventricular arrhythmias

The past 25 years have seen the implantable cardioverter defibrillator emerge as the treatment of choice for ventricular arrhythmias with reduction in size but increased therapeutic options. Understanding the complex mechanisms of ventricular arrhythmias and defibrillation in normal and diseased hearts has been the focus of many research teams including that of John Uther at the Westmead Hospital Department of Cardiology. Marked improvements in capacitor and battery technologies, arrhythmia discrimination, pacing algorithms, shock waveforms and monitoring capabilities enable wider use and patient acceptance. Emergence of cardiac resynchronisation therapy and the implantable defibrillator for treatment of chronic heart failure is not only giving quality of life and extended survival for heart failure patients but has also cast new light on the evolution of heart failure.