Widespread access to automated external defibrillators, particularly in public locations where sudden cardiac arrest is likely, is the way forward.
Ventricular fibrillation (VF) is a common cause of sudden cardiac death (SCD) and is sometimes preceded by monomorphic or polymorphic ventricular tachycardia (VT). Although cardiopulmonary resuscitation, including chest compressions and assisted ventilation, can provide transient circulatory support for the patient with cardiac arrest, the only effective approach for terminating VF is electrical defibrillation. Success with external defibrillation led to the development of an implantable cardioverter defibrillators (ICDs). There has been dramatic increase in the use of the ICDs to monitor VT or VF and to provide prompt treatment. Because of its high success rate in terminating VT or VF rapidly, results of multiple clinical trials showing improvement in survival, ICD implantation is generally considered the first-line treatment option for secondary prevention of SCD and for primary prevention in certain populations at high risk of SCD due to VT or VF.
Conventional ICDs have proved effective in the prevention of SCD, but they still appear to be limited by non-trivial acute and long-term complications. Conventional trans-venous ICD (TV-ICD) systems require one or more leads to be implanted into the heart through venous anatomy. While TV-ICDs are well tolerated by most patients, the invasive approach can be associated with severe complications, including systemic infections, cardiac injuries, and lead failures. An entirely subcutaneous ICD (S-ICD) system was developed as a less-invasive alternative to TV-ICDs without requiring leads in or on the heart. The S-ICD system provides therapy with a left lateral pulse generator and parasternal electrode configuration that is placed under the skin outside the rib cage, resulting in a much lower risk profile. The recent advent of S-ICD represents a further step in the evolution of defibrillation technology toward a less-invasive approach. This new generation of S-ICD demonstrates favorable features including a smaller device, longer longevity, and remote-monitoring compatibility. Further innovations in the S-ICD system and potential integration with leadless pacing may play an important role in defibrillation therapy and prevention of SCD in the near future.
Indian Market Dynamics
The Indian market for defibrillators in 2014 is estimated as 6430 units, at Rs.86 crore. The year saw an estimated 20 percent decline in monophasic defibrillators, which was offset by 20 percent increase in biphasic ones. The AED segment increased by 10 percent in 2014, over 2013. This is in volume terms.
The prices over the last couple of years have fallen drastically. Chinese products are infiltrating the market, and finding their way into smaller new hospitals and nursing homes being set up.
The government procurement is also largely determined by the extremely low prices quoted by the vendors. Some orders placed included 125 units by HLL (for AIIMS); 29 units of multichannel monitors and defibrillators and 100 units of AEDs by Tamil Nadu Medical Services Corporation Limited; and 100 defibrillators by Andhra Pradesh government.
Schiller and Philips continue to dominate this segment, with a combined market share in the vicinity of 70 percent. With the recent launch of Efficia DFM100 defibrillator in the value segment, Philips has further strengthened its position. The brand also offers Goldway products, having acquired all outstanding shares of Shenzhen Goldway Industrial, Inc. in 2008. BPL, Medtronic and Nihon Kohden are aggressive in this segment. Other popular brands include Zoll, Mindray, GE, Cardiac Science (marketed by AMDL), and Metrax.
Trends gaining popularity are those models which also offer an external pacemaker, and have ready-for-use indicators, and where remote monitoring is possible.
The industry expects the segment to get major impetus once the government takes a decision to provide widespread access to AEDs in community settings as primary health centers, buses, bus stops, schools, malls, recreation facilities, office buildings, and other public locations.
Sudden cardiac arrest is one of the leading causes of death. AED is the only effective treatment for restoring a regular heart rhythm during sudden cardiac arrest and time is of essence. For every one minute delay in defibrillation, the survival rate of a cardiac arrest victim decreases by 7-10 percent. After more than 12 minutes of ventricular fibrillation, the survival rate is less than 5 percent. Public access to AED program shows survival rates as high as 75 percent. This success is directly related to highly visible, readily accessible automated external defibrillators for public use and an integrated structured emergency response system.
The global defibrillators market is estimated to grow to USD 12.9 billion by 2019, at a CAGR of 6.9 per cent from 2015 to 2019. The market in the emerging countries of Asia-Pacific is poised to grow at the highest rate in the next five years. The global market growth is driven by the development of technologically advanced defibrillators, rapid growth in ageing population with high risk of target diseases, rising incidences of cardiovascular disease, growing focus of public and private organizations and key market players toward public access defibrillators, and increasing number of training and awareness programs across the globe. Moreover, emerging markets such as China, India, Brazil, and Mexico; home-use defibrillators; and development of S-ICDs are creating opportunities for market growth.
However, lack of awareness about sudden cardiac arrest, issues related to the use of defibrillator devices both external and implantable, and unfavorable healthcare reforms are restraining the growth of this market. In addition to this, the increasing pricing pressure on market players and frequent product recalls are the key challenges faced by the market players.
Automated external defibrillators. With recent advances in technology, AEDs are now widely available, safe, effective, portable, and easy to use. They provide the critical and necessary treatment for SCA. All worksites are potential candidates for AED programs because of the possibility of SCA and the need for timely defibrillation. Various technological innovations have made the AEDs more user-friendly and expanded their scope. Advanced functionalities, improved software, and integrated monitoring parameters continue to drive the market toward improved efficacy and point-of-care technology. The AED analyzes the electrocardiogram using four characteristics, signal amplitude, rate of complex occurrence, morphological stability of the complexes, and electrical signal conduction. Amplitude measurement is used only to identify the presence of asystole. All four measures are assessed concurrently and contribute to the final decision regarding whether shock should be administered. No single measure is capable of triggering a shock recommendation independently. Simplifications in AED design have resulted in shorter defibrillation times while minimizing the need for retraining. Self-adhesive electrode pads (provided with application diagrams) transmit rhythm information to the device and are also used to deliver shocks. Audible and text prompts guide the user through a few simple steps of operation. Rhythm is analyzed automatically and shock is recommended when indicated. Shock is delivered with the push of a button. The device automatically re-evaluates the rhythm within a preset time and determines whether to recommend an additional shock. Cardiac rhythms are automatically recorded for review.
Recent advances in ICD. Studies comparing dual and single chambered ICD have shown that both are equally effective in detection and treatment of malignant arrhythmias. The presence of an atrial lead may help discriminate VT from supraventricular tachycardia by identifying the presence of atrioventricular dissociation. In an ICD, defibrillation is performed by delivering a shock between a distal coil electrode located in the right ventricle and the ICD can act as a second electrode. Some ICD lead designs have a second coil located more proximally in the superior vena cava (SVC) and innominate veinthat is usually configured to act as a second anode. The additional surface area provided by the addition of the SVC coil has the theoretical advantage of reducing impedance and the amount of energy required to defibrillate the heart, formally measured as the defibrillation threshold. However, dual-coil leads are associated with an increased risk of complications associated with lead extraction, and single-coil leads are preferred in younger patients who have a higher likelihood of requiring future lead extraction.
Fully operational intravascular defibrillators have undergone testing, and may be a viable replacement for ICDs in future years. These defibrillators are anchored in the subclavian vein and descend down the vena cava via the right atrium. The device contains electrodes in the SVC and inferior vena cava and a single-coil lead in the right ventricle. Still in its infancy, the percutaneous ICD's efficacy remains untested, and many challenges surrounding generator exchange and explanation are foreseen. Dual and single chamberedICDs have shown that both are equally effective in detection and treatment of malignant arrhythmias.
The presence of an atrial lead may help discriminate VT from supraventricular tachycardia by identifying the presence of atrio-ventricular dissociation. Magnetic resonance imaging is often recommended for optimal imaging in a variety of settings. Magnetic resonance imaging is generally not recommended in patients with ICDs, although it can be performed in selected patients with ICDs if clinically necessary. All of the manufacturers have developed ICDs designed to function in the magnetic resonance imaging environment that are in varying stages of development and approval.
S-ICD scores over the conventional ICD. Mechanical complications related to the leads placed in the vascular system of traditional transvenous ICDs occur far too frequently, often with a heavy cost to the patient. Device-related infections also continue to adversely affect morbidity and mortality rates. Invasive implantation procedures and the need for more device replacement increase the risk of device infection technology was developed to overcome some of these problems. The initial challenge in the evolution of S-ICD systems was to prove that they were as effective in detecting and treating ventricular tachycardia and ventricular fibrillation as were traditional transvenous ICDs. The results of large clinical trials have confirmed the safety and efficacy of S-ICDs in treating ventricular arrhythmias. The next hurdle pertained to over sensing and the resultant inappropriate shocks, which occurred more often in S-ICD use than in transvenous ICD use during the early clinical experience. Optimisation of the S-ICD sensing algorithm, with the use of dual zones for detection, has yielded substantial improvement in the inappropriate-shock rate, which is now comparable to that of transvenous ICDs. The lack of pacing in S-ICDs currently limits theiruse to a population of patients who do not need antitachycardia pacing or cardiac resynchronization therapy. Despite these limitations, the implantation rate of S-ICDs is increasing, and new patient populations are being added.
Subcutaneous ICDs are particularly useful in patients with difficult or absent venous access. They should also be considered in patients at high risk for blood stream infection, such as those with indwelling intravascular catheters. In addition, they should also be considered in young patients who require defibrillators, since they eliminate the physical stress on leads associated with cardiac motion. The lack of demand pacing in these systems contraindicates their use in patients who require consistent pacing support. In addition, certain fast ventricular arrhythmias may be terminated by rapid pacing without the need for a high energy shock, and in such patients traditional transvenous ICD systems which have this capability would be preferred.
Leadless technology surging ahead. Most current ICD systems involve placement of lead transvenously into the heart, connected to a pulse generator. Vascular access may be difficult or limited in some patients, and intravascular leads can be associated with multiple complications such as infection, lead malfunction and vascular occlusion. Recent advances in ICDs include the development of subcutaneous ICDs and leadless pacing. Subcutaneous ICDs do not require a trans-venous access or lead, and have become an important option for patients with indications for ICDs who have limited or difficult vascular access or have a significant risk with this approach. In addition, subcutaneous ICDs can be offered as an alternative to trans-venous ICDs in certain patients. Leadless pacing is evolving as a new approach to pacing that can avoid or mitigate the issues associated with intravascular leads. Self-powered leadless cardiac pacemakers have been shown to be a safe and feasible option for patients requiring single chamber pacing. In addition, leadless ultrasound-based pacing has been shown to provide effective left ventricular pacing for cardiac resynchronization therapy in conjunction with a traditional trans-venous device. Future advances in the technology of leadless pacing will hopefully allow multi-chamber pacing with all the sophistication of current trans-venous systems. Perhaps, leadless pacing can even be combined with a subcutaneous ICD in the same patient.
The innovation of the ICD represents a modern medical achievement with substantial life-saving benefits for patients at risk for potentially life-threatening arrhythmias. ICD implantation dramatically changed the face of cardiac care. The introduction of the device was met by scepticism and outright rejection by some, yet large-scale clinical trials clearly demonstrated the mortality benefit of the ICD.
Today, specific challenges for this technology have emerged, including barriers to individual and social acceptance of the ICD as a viable form of technology, as well as psychosocial adjustment difficulties and fears in patients. To address these challenges, scientific research, improved communication regarding devices and psychosocial interventions have been developed and extended to patient population.
Computerization has rapidly paved the way for automated external defibrillation in resuscitation, much as it has toward stereotaxis in neurosurgery and magnetic resonance imaging. In some circumstances the use of AEDs improves both overall patient survival and neurological outcome after resuscitation. However, controversy persists regarding the optimal approach toward implementation of this technology. Government initiatives for creating awareness about the usefulness of AEDs in SCA will be the crucial factor for the growth of the market. Fully automated devices are preferred for public access, where users can be trained or untrained.