When was the first defibrillator implanted

Tip and ring conductors are used for pacing and sensing, a defibrillation conductor for the coil located in the right ventricle and a defibrillation conductor for the coil located in the superior vena cava. The major advantage of multilumen over coaxial leads is the fact that more conductors will fit into overall smaller leads [ 24 ].

Cross section of coaxial lead construction of a single coil defibrillation lead with true bipolar sensing and pacing left and cross section of multilumen lead construction right. Image provided by Medtronic. Despite improvements in the construction of leads, lead failure occurs frequently. Due to the different design and materials which are used, longevity of current implanted leads may differ significantly [ 25 ]. Borleffs et al. The implanted leads were produced by different manufacturers, and different lead diameters were used.

Based on these findings, it is important to carefully select the type of leads which are used for each patient and to optimise future lead performance [ 26 ]. Since the first implantation in , worldwide implantation rates have increased, and therefore, the number of ICD replacements is expected to increase dramatically.

Most of the replacements are due to end of service life battery depletion , and every implantation or replacement brings a substantial risk of complications.

Furthermore, the study suggested that if an ICD had ten service years, the majority of patients would not need a replacement [ 27 ]. A feasible solution is to produce larger pulse generators with batteries with longer service life. Furthermore, because of the fast development of new ICD features, it will sometimes be questionable if it is really desirable to implant devices with a projected longevity of ten or more years. Replacement of the currently used lithium-silver vanadium oxide batteries with large-capacity batteries can increase service life by 2.

These large-capacity batteries increase the size and weight of the device and are in conflict with downsizing the device as the market forces. First-generation devices were designed to detect VF only by waveform analyses. The standard waveform analysis used to identify cardiac rhythm was the rate of R waves.

Due to the limitations of waveform analyses only, inappropriate therapy occurred frequently, since episodes of supraventricular tachycardia with fast ventricular response could be classified as VT or VF and cause inappropriate shocks. The first detection criterion in all current devices is the signal rate recorded by the right ventricular lead. In order to confirm a ventricular tachyarrhythmia, a specified number of sensed events must occur at a higher rate than the cutoff rate.

To improve specificity in discriminating between VT or supraventricular tachycardia, various algorithms have been developed. As mentioned previously, current ICDs can be programmed into three different cycle length-related zones and the discriminative detection algorithms can be programmed in the two lowest zones.

The highest programmable zone is meant for detection of fast VT or VF without any further discrimination to avoid unnecessary therapy delivery delay. Single chamber devices use algorithms to discriminate rhythms, comparing the morphology of the arrhythmia with the morphology of baseline sinus rhythm, the rate of onset of arrhythmia and rhythm regularity.

Dual-chamber devices can use additional information retrieved from the atrial lead for discriminating between rhythms. All currently available algorithms have some known limitations such as false-positive and false-negative therapy delivery decisions, but by combining some of these algorithms, the amount of inappropriate inhibition or therapy delivery can be further reduced.

The complexity and combination of algorithms which can be used depends on power requirements of the ICD. Since downsizing the ICD is an important goal, larger batteries which can provide the power requirements for complex algorithms are not used. These constraints reduce the use of more complex algorithms, and despite advances in algorithms, inappropriate therapy still occurs.

Since the introduction of ICD therapy 25 years ago, many device improvements have been made in size and weight reduction, arrhythmia discrimination, battery technologies, shock waveforms, monitoring capabilities and new defibrillator electrodes, which have led to wider use and greater patient acceptance.

In the beginning of ICD therapy, patients had to survive a life-threatening VA to be eligible for ICD treatment, but due to minimal survival rates, focus shifted to the identification of patients at high risk.

Over the years, many secondary and primary trials have been executed, and the findings led to evolving guidelines for ICD implantation. The ICD is currently regarded as everyday therapy for large patient groups worldwide. Although the beneficial effects of ICD therapy are clearly proven in a selected population, ongoing advances in ICD technology and patient selection are necessary to improve device longevity, lead survival and to minimise the occurrence of adverse events.

This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author s and source are credited. The questions can be answered after the article has been published in print. National Center for Biotechnology Information , U.

Journal List Neth Heart J v. Neth Heart J. Published online Dec Borleffs , J. Atary , J. Thijssen , E. Author information Copyright and License information Disclaimer. Corresponding author. This article has been cited by other articles in PMC. Abstract In , Dr. Keywords: Implantable cardioverter defibrillator, Cardiac resynchronization therapy, Arrhythmia, Sudden death, Defibrillation.

Introduction Sudden cardiac death, mainly caused by ventricular arrhythmias VA in a population with coronary artery disease, is a major cause of mortality in the Western world. Secondary Prevention Trials Initially, to be eligible for ICD treatment, patients had to survive at least one episode of life-threatening VA such as ventricular fibrillation VF or ventricular tachycardia VT; secondary prevention.

Table 1 Clinical features and results of three major secondary prevention ICD trials. Open in a separate window. Table 2 Clinical features and results of four primary prevention ICD trials. Cardiac Resynchronisation Therapy Defibrillator Congestive heart failure CHF is associated with decreased haemodynamic function, exercise tolerance and quality of life due to poor left ventricular systolic or diastolic function.

The Device The first ICD was large and heavy, could not be programmed, used epicardial patch electrodes and required a thoracotomy for the implantation of the epicardial lead system. Components and Function An ICD contains a battery, a capacitor to store and deliver charges, a microprocessor and integrated circuits for electrogram sensing, data capture, storage and control of therapy delivery, a header to connect the endocardial leads used for sensing, pacing and defibrillation Fig. Battery and Capacitor First-generation devices contained cylindrical aluminium electrolytic capacitors and silver vanadium pentoxide batteries for rapid charge time and the delivery of high-voltage shocks [ 21 ].

Leads The large first-generation devices were implanted abdominally and needed a thoracotomy to place the lead system. Longevity Since the first implantation in , worldwide implantation rates have increased, and therefore, the number of ICD replacements is expected to increase dramatically. Algorithms and Rhythm Discrimination First-generation devices were designed to detect VF only by waveform analyses. Conclusions Since the introduction of ICD therapy 25 years ago, many device improvements have been made in size and weight reduction, arrhythmia discrimination, battery technologies, shock waveforms, monitoring capabilities and new defibrillator electrodes, which have led to wider use and greater patient acceptance.

Open Access This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author s and source are credited. Over time, the technology of ICDs has improved. They are essentially implantable computers that keep track of a patient's heart rhythm by pacing protecting from slow heart rates and treating fast rhythms.

For example, they can pace-terminate a fast rhythm called ventricular tachycardia without resorting to a shock. In fact, the device could detect and treat a life-threatening arrhythmia without the patient even knowing. ICDs can also pace both sides of the heart for patients with conduction problems that benefit from biventricular pacing.

Implantable cardioverter defibrillators ICD are advised in specific patients who are at risk for potentially fatal ventricular arrhythmias, an abnormal rhythm from the lower heart chambers which can cause the heart to pump less effectively. There may be other reasons why your physician advises placement of a pacemaker or ICD. Conditions and Treatments. Traditional transvenous implantable cardioverter-defibrillator Traditional implantable cardioverter-defibrillators ICD sit in the chest and send a shock to the heart when they sense an abnormal rhythm.

How do implantable cardioverter defibrillators work? Expand Content This device is designed to deliver two levels of electrical energy. The recommendations for ICD use for secondary prevention are presented in Table 1.

Devices also remain expensive and require long-term follow-up at specialized centres experienced in their management. Considerable research has therefore centred on attempting to identify patients at highest risk for SCD and cases where the potential benefits of ICD use outweigh the risks and the cost.

The risk of SCD is also dependent on the cause of the reduced ejection fraction. Importantly, most of these trials enrolled patients at least 1 month after MI in an effort to exclude any patient whose ejection fraction was likely to improve with recovery of stunned myocardium.

In fact, implantation of an ICD immediately after MI in those with depressed ejection fractions conferred no benefit in two recent trials. The trials of ICD for primary prevention in patients with nonischemic cardiomyopathies were less conclusive. The two earliest trials showed no benefit with ICD use, but they were small and likely underpowered. Two larger subsequent trials showed a reduction in SCD and overall mortality, albeit a smaller reduction than that seen in the ischemic heart disease population.

Therefore, it is recommended that these patients be on maximal medical therapy for at least 9 months before assessing their candidacy for an ICD. There is also a role for ICDs in the primary prevention of SCD in patients who have preserved ejection fractions but conditions that predispose them to ventricular arrhythmias such as hypertrophic cardiomyopathy, long QT syndrome, arrhythmogenic right ventricular cardiomyopathy, or Brugada syndrome.

An evaluation by an electrophysiologist is essential for identifying high-risk patients who would benefit from an ICD. The Canadian and American guidelines differ somewhat in their recommendations and we have emphasized the Canadian recommendations where conflicts arise.

When not to implant As well as knowing who might benefit from ICD therapy, it is important for treating physicians to know who is not an appropriate candidate see Table 3. This includes patients with VT or VF within the first 48 hours of an acute MI due to electrolyte abnormalities or due to the effects of drug use or intoxication. Patients with incessant VT or VF are also not candidates for an ICD until their arrhythmia is brought under control with antiarrhythmic or ablation therapies.

Similarly, patients whose life expectancy is less than 1 year due to cardiac or noncardiac disease are not likely to survive to benefit from an ICD. Competing interests Dr Tung has received research funding from Medtronic Canada. He has also received speaking fees from Boston Scientific Canada and St.

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