Trends in cardiac pacemaker batteries

Batteries used in Implantable cardiac pacemakers-present unique challenges to their developers and manufacturers in terms of high levels of safety and reliability. In addition, the batteries must have longevity to avoid frequent replacements. Technological advances in leads/electrodes have reduced energy requirements by two orders of magnitude. Micro-electronics advances sharply reduce internal current drain concurrently decreasing size and increasing functionality, reliability, and longevity. It is reported that about 600,000 pacemakers are implanted each year worldwide and the total number of people with various types of implanted pacemaker has already crossed 3 million. A cardiac pacemaker uses half of its battery power for cardiac stimulation and the other half for housekeeping tasks such as monitoring and data logging. The first implanted cardiac pacemaker used nickel-cadmium rechargeable battery, later on zinc-mercury battery was developed and used which lasted for over 2 years. Lithium iodine battery invented and used by Wilson Greatbatch and his team in 1972 made the real impact to implantable cardiac pacemakers. This battery lasts for about 10 years and even today is the power source for many manufacturers of cardiac pacemakers. This paper briefly reviews various developments of battery technologies since the inception of cardiac pacemaker and presents the alternative to lithium iodine battery for the near future.     

In-vitro mapping of E-fields induced near pacemaker leads by simulated MR gradient fields

Background  

Magnetic resonance imaging (MRI) of patients with implanted cardiac pacemakers is generally contraindicated but some clinicians condone scanning certain patients. We assessed the risk of inducing unintended cardiac stimulation by measuring electric fields (E) induced near lead tips by a simulated MRI gradient system. The objectives of this study are to map magnetically induced E near distal tips of leads in a saline tank to determine the spatial distribution and magnitude of E and compare them with E induced by a pacemaker pulse generator (PG).     

An on-line realtime cardiotachograph]

A realtime cardiotachogram was devised to detect fluctuation of cardiac rhythm. The apparatus is composed of five parts; (1) a "preamplifier" for recording electrical and/or mechanical cardiac activities, (2) a "slicer" to obtain sampling pulses from cardiac activity at a certain trigger level, (3) a "trigger pulse generator" to monitor sampling pulse, (4) an "oscillator" whose output is fed to a pulse counter, and (5) a "pulse counter" which counts the outputs of the oscillator during the gating period determined by the sampling pulses. The count numbers are converted to analog output, thus we can get sawtooth wave whose amplitude is directly proportional to the cardiac interval. The cardiac intervals between 100 ms and 5 seconds can be recorded by this tachograph.     

Possible complications of subclavian crush syndrome

A 70-year-old woman with symptomatic Mobitz type II atrioventricular block underwent implantation of a dual-chamber pacemaker 11 years ago. The leads were inserted through a percutaneous puncture of the right subclavian vein, using standard techniques. Both leads were passive fixation leads. Due to battery failure and end of life criteria, the pulse generator (PG) had been routinely replaced six years previously. Predischarge pacemaker control revealed normal pacing, sensing thresholds and impedance for both leads. Because of a syncopal attack subsequent to lead fractures, most likely secondary to right subclavian crush syndrome (SCS) of both leads, she underwent a double lead re-implantation one year after PG replacement by access via left subclavian vein puncture.After a symptom-free period of few years she was re-analysed because of palpitations, dizziness, angina pectoris and tiredness. Pulmonary embolisation and myocardial perfusion defects were detected utilising scintigraphic techniques. Chest X-ray revealed the crushed atrial lead dislocated from the right subclavian region and lodged into the right ventricle towards the inferior septum. Because she was symptomatic, a retrieval technique was applied and the crushed atrial lead was pulled back from the right ventricle and securely fixed to its former position. On maintenance medical treatment, she remains well.     

The Artificial Cardiac Pacemaker—Indications for Implantation

Extensive clinical experience has demonstrated that implantable cardiac pacemakers are safe and effective mechanisms for controlling symptoms and preventing the hazards of third degree heart block with Stokes-Adams syncope. Medical management of this disease does not provide reliable protection and life expectancy averages about two years after diagnosis. Hence the negligible surgical morbidity and mortality associated with pacemaker implantation justifies broad indications to implant one of the four commercially available battery-powered units.Elective implantation of a pacemaker should be considered in patients with persistent third degree heart block who have had: One or more episodes of Stokes-Adams syncope; surgical injury to the conduction system, regardless of syncopal attacks; evidence of low cardiac output with cardiomegaly secondary to bradycardia. Few if any other cardiac arrythmias are satisfactorily controlled by an electrical pacemaker.Emergency pacemaker control is obviously necessary for patients developing intractable or recurrent bouts of asystole. During the interval until an implantable unit can be obtained and sterilized, the patient may be controlled by intravenous isoproterenol or by an external pacemaker attached to a transvenous catheter electrode, a precordial skin electrode or a percutaneous myocardial wire electrode.     

A patient with dizziness,tachycardia and a DDDR pacemaker

An 84-year-old female patient presented to the coronary care unit with dizziness. A DDD-R minute ventilation sensor pacemaker had been implanted eight years previously. The ECG showed an atrial and ventricular paced rhythm of 140 beats/min. After disconnecting the patient from the cardiac monitor the pacemaker rate dropped gradually to 90 beats/min. The cardiac rhythm monitoring system applies low-amplitude electrical pulses in order to measure respiration rate by transthoracic impedance (TTI) measurement. The minute ventilation pacemaker sensor is driven by the same TTI measurement for rate response. Inappropriate interference between these two systems caused a sensor-driven high pacemaker rate. The dizziness was not related to the sensor-driven high rate.     

Cardiopulmonary arrest and resuscitation in Landrace/Large White swine: a research model

Sudden cardiac death (SCD) is a field of continuous research. In order to answer various questions regarding SCD, several animal models have been developed. The aim of the present study is to describe our experimental model of inducing cardiac arrest in Landrace/Large White pigs, and then resuscitated according to the International Guidelines on resuscitation. Fifteen Landrace/Large White pigs were anaesthetized and intubated while spontaneously breathing. The left and right jugular veins, as well as the femoral and the carotid arteries, were surgically prepared. Induction of cardiac arrest was achieved by using an ordinary rechargeable lithium battery, through a pacemaker wire inserted into the right ventricle. The typical Advanced Life Support (ALS) protocol was followed, and in case of restoration of spontaneous circulation, the animals were further evaluated for 30 min. Seven animals were successfully resuscitated using this protocol, whereas eight failed resuscitation efforts. Successful resuscitation was contingent on the restoration of the levels of coronary perfusion pressure and PETCO(2) during chest compressions. Among the different ways of inducing cardiac arrest, the ordinary lithium battery is a simple, safe and valuable technique. Landrace/Large White pigs' baseline haemodynamics closely resemble human haemodynamics, making the breed a favourable model for resuscitation.     

Utilisation of cardiac pacemakers over a 20-year period: Results from a nationwide pacemaker registry

The implantation of cardiac pacemakers has become a well-established therapy for conduction disorders and sinus node dysfunction. In many countries pacemaker registries have been initiated in order to collect information on patient characteristics, trends in numbers and the types of pacemakers used, to identify problematic devices, and for safety monitoring. For this utilisation study the Central Pacemaker Patients Registration (CPPR) from the Netherlands Pacemaker Registry Foundation (CPPR-SPRN) containing data collected for more than 20 years was used. During this period nearly 97,000 first pacemakers were implanted. Analyses show an increase in the rate of implanted devices. The change in pacemaker type from VVI to DDD, followed by biventricular stimulation, is reflected by the number of simultaneously implanted leads, which is partly a consequence of cardiac resynchronisation therapy. Our data demonstrate that indications for implantation and type of pacemaker are comparable with other European countries.     

Permanent cardiac stimulation in a patient with isolated dextrocardia and ventricular septal defect

A case of pacemaker implantation because of acquired atrioventricular block third degree in woman aged 39 years with rare isolated dextrocardia with inversion of cardiac ventricles, compensatory transposition of both aorta and pulmonary artery, and ventricular septal defect. The end of electrode has wedged in the apex of the arterial ventricle. Following pacemaker implantation, patients clinical course of gynaecological operation was uneventful.     

A Novel Picosecond Pulse Generation Circuit Based on SRD and NLTL

Because of the importance of ultra-wideband (UWB) radar in various applications, short pulse generation in UWB systems has attracted a lot of attention in recent years. In order to shorten the pulse, nonlinear transmission line (NLTL) is imported, which expands the application of step recovery diode (SRD) for pulse generation. Detailed analysis and equations for this SRD and NLTL-based pulse generation are provided and verified by simulation and experimental results. Factors that could cause pulse waveform distortions are also analyzed. The generator circuit presented in this paper generates 130ps and 3.3V pulse, which can be used in UWB radar systems that require sub-nanosecond pulses.     

Autonomic transmitter actions on cardiac pacemaker tissue: a brief review

Application of the voltage clamp technique to cardiac primary pacemaker tissue has yielded sufficiently detailed information that a qualitative model of the pacemaker response can now be formulated. One important difference between the generation of spontaneous activity in sinus tissue, and in the Purkinje fiber, appears to be the involvement of the slow inward current, Isi, in the sinus pacemaker depolarization. The voltage clamp results also demonstrate the importance of the Isi in the chronotropic responses of pacemaker tissue. Epinephrine has been shown to increase Isi in rabbit sinoatrial node, and there is indirect evidence that acetylcholine may reduce Isi in reptilian sinus venosus. Additional, more quantitative data are essential, however, before cardiac primary pacemaker activity and its modulation by the autonomic transmitters can be fully understood.     

Stem cell–based biological pacemakers from proof of principle to therapy: a review

Electronic pacemakers are the standard therapy for bradycardia-related symptoms but have shortcomings. Over the past 15 years, experimental evidence has demonstrated that gene and cell-based therapies can create a biological pacemaker. Recently, physiologically acceptable rates have been reported with an adenovirus-based approach. However, adenovirus-based protein expression does not last more than 4 weeks, which limits its clinical applicability. Cell-based platforms are potential candidates for longer expression. Currently there are two cell-based approaches being tested: (i) mesenchymal stem cells used as a suitcase for delivering pacemaker genes and (ii) pluripotent stem cells differentiated down a cardiac lineage with endogenous pacemaker activity. This review examines the current achievements in engineering a biological pacemaker, defines the patient population for whom this device would be useful and identifies the challenges still ahead before cell therapy can replace current electronic devices.     

The challenge of staphylococcal pacemaker endocarditis in a patient with transposition of the great arteries endocarditis in congenital heart disease

Staphylococcus aureus is a leading cause of septicaemia and infective endocarditis. The overall incidence of staphylococcal bacteraemia is increasing, contributing to 16% of all hospital-acquired bacteraemias. The use of cardiac pacemakers has revolutionized the management of rhythm disturbances, yet this has also resulted in a group of patients at risk of pacemaker lead endocarditis and seeding in the range of 1% to 7%. We describe a 26-year-old man with transposition of the great arteries who had a pacemaker implanted and presented with S. aureus septicaemia 2 years postpacemaker implantation and went on to develop pacemaker lead endocarditis. This report illustrates the risk of endocarditis in the population with congenital heart disease and an intracardiac device.     

Neural spike generator entrainment by regularly spaced synaptic input

 It has been known for 30 years that the output of a repetitively firing neuron or pacemaker can be synchronized (locked) to regularly spaced inhibitory or excitatory postsynaptic input potentials. Conditions for stable locking have been determined mathematically, demonstrated in computer simulation, and locking has been observed in vivo. We have developed a neural spike generator circuit model which exhibits stable locking to externally derived simulated inhibitory or excitatory post-synaptic inputs. Conditions for stable 1 : 1 lock, in which pacemaker output frequency matches that of the periodic input, are derived. These take the form of expressions for stable delay and convergence factor which incorporate known or measurable parameters of the circuit model. The expressions have been evaluated and shown to compare satisfactorily with experimental observations of locking by our circuit model. Received: 28 March 1996 / Accepted in revised form: 18 February 1997     

Neuronal control of heart reversal in the hawkmoth Manduca sexta

Cardiograms demonstrate that heart activity of Manduca sexta changes from larva, to pupa, to adult. The larval heart has only anterograde contractions. During metamorphosis, heart activity becomes a cyclic alternation of anterograde and retrograde contractions. Thus, the adult heart has both an anterograde and a retrograde pacemaker. External stimuli also can initiate cardiac reversal. Cardiac reversal is blocked by tetrodotoxin, indicating that reversal is under neuronal control. A branch of each dorsal nerve 8 innervates the posterior chamber of the heart, the location of the anterograde pacemaker. Only retrograde contractions occur when dorsal nerves 8 are cut. Stimulation of ml(-1) 8 initiates anterograde contractions; when stimulation ceases, the heart reverses to retrograde contractions. These experiments indicate that the anterograde pacemaker receives neural input that makes it the dominant pacemaker. In the absence of neural input this pacemaker is inactive, and the retrograde pacemaker becomes active. Application of crustacean cardioactive peptide accelerates the heart but does not eliminate cardiac reversal. The terminal chamber of the heart is also innervated by a branch of each dorsal nerve 7; stimulation of this nerve increases the strength of contraction of the terminal chamber but has no effect on contractions of the remainder of the heart or on cardiac reversal.     

Phase Resetting of the Human Circadian Pacemaker with Use of a Single Pulse of Bright Light

Since the initial studies reporting that light can alter the phase position of the human circadian system, there has been increasing interest in the use of bright light as a tool for manipulating the phase position of the circadian pacemaker. Exposure protocols typically require subjects to receive 2–5 h of exposure over several circadian cycles. As a consequence, bright light treatment can involve a considerable time investment. However, recent studies indicate that a single pulse of bright light can produce significant phase shifts in the circadian pacemaker. If a single pulse of bright light can produce significant phase-shifting effects, multiple-pulse designs may be unnecessary. This study examined the phase-shifting effects of a single 4-h pulse of bright light (12,000 lux) in 14 male and one female subject aged between 19–45 years. With use of a “constant routine” to estimate circadian phase, a single 4-h pulse of light produced significant shifts in the phase of the core temperature rhythm. The timing of the exposure, relative to the core temperature rhythm, determined the degree and direction of the phase shift. Exposure immediately prior to habitual bedtime produced a mean phase delay in the core temperature of 2.39 h (SD = 1.37 h). In contrast, exposure immediately following habitual wake-up produced a mean phase advance of 1.49 h (SD = 2.06 h). In addition, the magnitude of the shift increased the closer the light pulse was to the individual's estimated endogenous core temperature minimum. There was, however, considerable interindividual variability in this relationship. Overall, these results confirm that a single pulse of bright light can produce significant phase shifts in the phase of the circadian pacemaker controlling core temperature.     

Phase Resetting of the Human Circadian Pacemaker with Use of a Single Pulse of Bright Light

Since the initial studies reporting that light can alter the phase position of the human circadian system, there has been increasing interest in the use of bright light as a tool for manipulating the phase position of the circadian pacemaker. Exposure protocols typically require subjects to receive 2-5 h of exposure over several circadian cycles. As a consequence, bright light treatment can involve a considerable time investment. However, recent studies indicate that a single pulse of bright light can produce significant phase shifts in the circadian pacemaker. If a single pulse of bright light can produce significant phase-shifting effects, multiple-pulse designs may be unnecessary. This study examined the phase-shifting effects of a single 4-h pulse of bright light (12,000 lux) in 14 male and one female subject aged between 19-45 years. With use of a “constant routine” to estimate circadian phase, a single 4-h pulse of light produced significant shifts in the phase of the core temperature rhythm. The timing of the exposure, relative to the core temperature rhythm, determined the degree and direction of the phase shift. Exposure immediately prior to habitual bedtime produced a mean phase delay in the core temperature of 2.39 h (SD = 1.37 h). In contrast, exposure immediately following habitual wake-up produced a mean phase advance of 1.49 h (SD = 2.06 h). In addition, the magnitude of the shift increased the closer the light pulse was to the individual's estimated endogenous core temperature minimum. There was, however, considerable interindividual variability in this relationship. Overall, these results confirm that a single pulse of bright light can produce significant phase shifts in the phase of the circadian pacemaker controlling core temperature. Key Words: Bright light—Circadian rhythm—Core body temperature—Sleep-wake disorders—Chronobiology.     

Transcatheter leadless permanent pacemaker in complex congenital heart disease with interrupted inferior vena cava: A challenging implantation

31 years lady with complete atrioventricular canal defect, large primum atrial septal defect (ASD), inlet ventricular septal defect (VSD) and Eisenmenger syndrome, presented with atrial flutter and complete heart block. She was not suitable for corrective cardiac surgery and not yet indicated for heart-lung transplantation. She was advised single chamber permanent pacemaker and eventually Micra VR transcatheter leadless pacemaker was finalised for her. Transcatheter leadless pacemaker was deployed in her RV septum despite some unforeseen technical problems. This patient had intrahepatic interruption of IVC with Azygous continuation draining into SVC but this altered venovascular course was detected only fluoroscopically midway during the pacemaker implantation procedure and this was not detected in the preprocedural transthoracic echocardiography. This abnormal venous course was clearly demonstrated in the cardiac CT which was performed only after completion of the pacemaker implantation procedure in this patient. The technical challenges encountered mainly were mostly during the manipulation of the 27F delivery catheter of Micra through this altered cardiovascular anatomy via transfemoral approach and also due to the presence of septal defects. Thus, transcatheter leadless permanent pacemaker was implanted successfully through transfemoral access in this complex congenital heart disease with interrupted IVC and azygous continuation. Besides transthoracic echocardiography, it may be better to perform transesophageal echocardiography or even preferably radiological imaging like cardiac CT or MRI prior to transcatheter leadless pacemaker implantation in patients with complex congenital heart disease to understand the cardiovascular anatomy and plan the procedure.     

Long-term in vivo experience of an electrochemical sensor using the potential step technique for measurement of mixed venous oxygen pressure

An implantable amperometric blood oxygen sensor was developed to improve rate adaptation of heart pacemakers. Two different working electrode materials in direct contact with the blood were tested, smooth glassy carbon and gold. Reference electrodes of Ag/AgCl and porous pyrolytic carbon were evaluated. A counter electrode being the titanium housing of the pulse generator was partly coated with carbon. An implantable pacemaker system with chronocoulometric oxygen detection was developed. Heart synchronous potential steps were periodically applied to the 7.5 mm² working electrode in the atrium. Both single and double potential step techniques were evaluated. The oxygen diffusion limited current was used to calculate the stimulation rate. Bench tests and studies on 31 animals were performed to evaluate long-term stability and biocompatibility. In five dogs, the AV node was destroyed by RF ablation to create a realistic animal model of a pacemaker patient. Sensor stability and response to exercise was followed up to a maximum implantation time of 4 years. Post-mortem examinations of the electrode surfaces and tissue response were performed. The results show that a gold electrode is more stable than glassy carbon. The Ag/AgCl reference was found not to be biocompatible, but activated carbon was stable enough for use as reference for the potentiostat. Double potential steps stabilize the sensor response in comparison to single steps. Blood protein adsorption on the gold surface decreased the oxygen transport but not the reaction efficacy. No adverse tissue reactions were observed.