ECG patch monitors for assessment of cardiac rhythm abnormalities.

The primary goal of long-term monitoring is the improvement of diagnostic yield. Despite the clear utility of Holter monitoring in clinical cardiology, issues of relatively low diagnostic yield, cost and inconvenience have motivated the development of ultra-portable devices referred to as ECG patch monitors. Although the "gold standard" for assessing cardiac rhythm abnormalities remains a 12-lead Holter, there is an increasing interest in portable monitoring devices that provide the opportunity for evaluating cardiac rhythm in real-world environments such as the workplace or home. To facilitate patient acceptance these monitors underwent a radical miniaturization and redesign to include wireless communication, water proofing and a patch carrier for attaching devices directly to the skin. We review recent developments in the field of "patch" devices primarily designed for very long-term monitoring of cardiac arrhythmic events. As the body of supporting clinical validation data grows, these devices hold promise for a variety of cardiac monitoring applications. From a clinical and research standpoint, the capacity to obtain longitudinal cardiac activity data by patch devices may have significant implications for device selection, monitoring duration, and care pathways for arrhythmia evaluation and atrial fibrillation surveillance. From a research standpoint, the new devices may allow for the development of novel diagnostic algorithms with the goal of finding patterns and correlations with exercise and drug regimens.

The subcutaneous defibrillator.

OPINION STATEMENT: Prevention of sudden cardiac death (SCD) remains an important clinical problem. Currently, therapeutic goals for SCD prevention include identification of high risk patients and aggressively treating comorbidities underlying. However, many patients remain at increased risk despite optimal medical management (eg, coronary artery disease and cardiomyopathy) whereas others have nonmodifiable risk for sudden death (eg, arrhythmogenic right ventricular dysplasia/cardiomyopathy, Brugada syndrome, long QT syndrome, and hypertrophic cardiomyopathy). In such patients, device therapy with an implantable defibrillator remains the most effective therapy for SCD prevention. However, implantable cardioverter defibrillators (ICDs), which are typically implanted with at least 1 lead placed within the heart, are associated with risks related to device implantation, as well as the presence of chronic endovascular leads. The durability of chronic leads is variable and can require either new leads to be placed or require lead extraction, which is associated with significant morbidity and mortality. The recently developed subcutaneous ICD (S-ICD) does not rely on any component to be placed within the heart or vasculature and therefore may mitigate the risks associated with endovascular leads. Therefore, it may be preferred for patients who are young, have inherited channelopathies, are immunocompromised, have indwelling catheters, or in whom venous access is obstructed or unfavorable due to congenital heart disease. Though long-term data regarding S-ICD performance are not yet available it may prove to be an effective therapeutic option for prevention of SCD.

New devices for very long-term ECG monitoring.

Present day 24-h Holter monitors have been shown to miss many arrhythmias that may occur infrequently or under specific circumstances. The advancement in electronic and adhesive technologies have enabled the development of first generation wearable long-term 14-day patch ECG monitors that attach directly to the skin and require no electrodes and wires to operate. This new technology is unobtrusive to the patients and offers them unprecedented mobility. It enables very long-term monitoring of critical patients while they are carrying out daily activities. The monitors are waterproof, offer good adhesion to the skin and can operate as either recorders or wireless streaming devices.

Recent innovations in the development of magnetic resonance imaging conditional pacemakers and implantable cardioverter-defibrillators.

The first generation of magnetic resonance conditional pacemakers and implantable cardioverter-defibrillators has finally arrived in clinical practice after many years of development. These devices have been optimized to properly function within magnetic fields of 1.5 T and ensure safe operation in controlled environments. Further progress is needed to develop a new generation of magnetic resonance imaging (MRI) conditional devices that can operate in higher powered MRI machines (3 T) which produce clearer images.

New developments in the treatment of severe drug resistant hypertension.

The purpose of this paper is to review the state-of-the-art of renal denervation system technology for treatment of drug resistant hypertension. We describe an investigational device that is currently tested in an on-going clinical trial. The denervation device uses the RF thermal ablation catheter attached to the RF generator. The RF catheter is inserted into the renal artery and positioned in the vicinity of the efferent and afferent parasympathetic innervations. Renal denervation is a minimally invasive, localized procedure and the procedural and recovery times are very short. The entire procedure lasts about 40 min. In early clinical trials, the systolic blood pressure in 87% of patients who underwent the denervation procedure resulted in an average blood pressure drop of greater than 10 mm Hg. The procedure has no systematic side effects, and appears to be beneficial in the management of hypertension in patients refractory to pharmacological therapy.

Subcutaneous implantable cardioverter-defibrillator (S-ICD).

Current state-of-the art implantable cardioverter-defibrillator (ICD) systems have been proven to be safe and effective in treating ventricular arrhythmias leading to cardiac death. ICDs require placement of at least one lead in, or on, the heart. Surgical placement under fluoroscopy and the ongoing presence of the transvenous leads within the patient's heart are associated with a significant proportion of the complications related to this well-established and highly effective therapy. A new ICD has been developed that is implanted entirely subcutaneously (S-ICD), thus eliminating the need for lead placement in or on the heart and simplifying surgery by eliminating the need for imaging equipment. Recent clinical studies suggest that the S-ICD system provides a viable alternative to conventional transvenous devices that may reduce barriers to treatment and lead to the wider adoption of this life-saving therapy.

Integrated heart failure telemonitoring system for homecare.

The integrated telemonitoring system (ITS) for homecare has been designed to improve quality of care as measured by increased nursing productivity, improved patients' clinical and behavioral outcomes and reduction of cost. The system incorporates managerial, organizational, operational and clinical tasks optimized for delivery of quality care through telemonitoring. A secure, multi-modal computer network that integrates homecare nurses, patients and those who care into one seamless environment has been developed. The network brings together a new generation of small, hand-held, wireless terminals used by nurses and patients with a HIPPA-compliant electronic patient record system at the caregiver's site. Wireless terminals use Gobi multi-standard networking technology for connectivity to any available wireless network. The unique features of ITS include a) picture recognition technology capable of extracting numeric data from in-home physiological signal monitor displays that include blood pressure, weight, oxygen saturation, transmission of lung sounds, and capturing echocardiography and electrocardiography data from mobile units; b) in-home caregiver-assisted interactive examinations of signs and symptoms that include visual impressions of ankle swelling, jugular vein distension measurement, and weight gain; c) video-conference capability, facilitating face-to-face two-way communication of nursing personnel with the patients. The ITS network has been designed to improve patients' clinical and behavioral outcomes, increase nursing productivity, and reduce the cost of homecare. Patients' co-operation and compliance has been achieved through use of easy-to-use videoconferencing terminals.

New material for implantable cardiac leads.

UNLABELLED: Cardiac function management devices, including implantable pacemakers and implantable defibrillators, include at least 1 cardiac lead having an electrode for making contact with a portion of the heart. It has been previously shown that the braided multifilament wire electrodes have a high failure rate both for sensing of spontaneous heart activity and for safe heart stimulation. Therefore, it is desirable to have cardiac leads made of materials with mechanical and electrical properties to insure safe pacemaker function. We have developed a new fiber material suitable for implantable cardiac leads with superior high modulus, high mechanical strength, and excellent electrical conductivity. METHODS: The material comprises poly(p-phenylene benzobisoxazole) fibers plated with gold by using an electroless plating method. Due to the difficulty in plating gold directly on organic and inorganic fibers, gold plating was carried out on the surface of silver-plated fibers. RESULTS: The morphology of plated fibers was studied by x-ray diffraction, scanning electron microscopy with energy dispersive spectroscopy, and electrochemical polarization measurements. It was found that gold was uniformly plated on the poly(p-phenylene benzobisoxazole) fiber, and the gold-plated fibers have good corrosion resistance. The electrical conductivity of the gold-plated fibers was higher than 4 x 104 S/cm, and its tensile strengths and Young moduli were greater than 1.9 and 130 GPa, respectively, when estimated in terms of a single-fiber strand. CONCLUSIONS: The metal-clad polymer fibers have advantages over conventional metal cardiac leads in flexibility, weight savings, mechanical strength, durability, and tailored electrical conductivity. Therefore, the combined engineering properties of the new fiber afford implantable cardiac lead applications at reduced diameter while having higher strength. Furthermore, the new fiber can be terminated just like a regular metal wire with the choice of ultrasonic bonding, crimping, or band connection.