Different Types Of Pacemakers Research Articles

Changes of endothelial function and intracardiac hemodynamics during implantation of different types of pacemakers

Aim. To determine the dynamics of endothelial function and intracardiac hemodynamics during implantation of different types of pacemakers. Material and methods. The study involved 61 patients, 29 of them were implanted with single-chamber pacemaker (the first group), 32 — two-chamber pacemaker (second group) with sick sinus syndrome (SSS), as well as patients with 2-3 degrees AV conduction disorder. Test with endothelium-dependent vasodilation of the brachial artery was performed using the standard technique and the velocity parameters of blood flow were determined. Parameters of intracardiac hemodynamics and left atrial (LA) function were determined. These studies were conducted in patients initially upon admission to the hospital and 2 months later implantation of pacemaker. Results. Endothelium-dependent vasodilation significantly deteriorated in patients with single-chamber pacemaker which initially was 6,1 [2,74;9,815]% and in 2 months decreased to 5,4 [2,37;7,55]% (p=0,05). There was a tendency to deterioration of left ventricular (LV) contractile function accompanied by a decrease in ejection fraction (EF) to 55,04 [49,04;68,72]%, and decrease emptying fraction of LA to 37,36 [31,67;52,85]%. There was a tendency to increase the volume index of LA which indicates an increasing overload of the volume and pressure of LA. There was a significant increase in the degree of endothelium-dependent vasodilation in patients of the second group initially compiling a 3,25 [2,15;6,61]% and then reaches 6,15 [2,75;8,97]% 2 months after surgery (p <0,04). There was no overload in the volume and pressure of LA and improved indirect signs of LV compliance parameters (growth of end-systolic dimension and volume) and decreased LV EF to 53,23 [44,1;69,95]%. In patients in the first group there was a tendency to increase peripheral resistance to 1227 [1065;1318] dyne x cm -5 x sec, accompanied by a significant decrease in blood flow rate. In the second group there was a tendency to reduce peripheral resistance to 1215 [1136;1391] dyne x cm -5 x sec and a significant increase in blood flow rate. There was a significant correlation between the systole LA dimension and total peripheral resistance in patients with VVI stimulation (r=0,78, p=0,0022), which indicates an increase in total peripheral resistance with a change in blood flow from LA to LV and a decrease in cardiac output. Conclusion. Endothelial function deteriorates with single-chamber stimulation and improves with two-chamber stimulation. These changes are based on shear stress and nitric oxide endothelium secretion the changes of which depend on the characteristics of central and peripheral hemodynamics.

Cardiovascular events follow-up analysis in patients with sinus node dysfunction and implanted pacemaker

Dysfunction of sinus node (DSN) is the syndrome, characterized by symptoms of tissue hypoperfusion and manifestations on the electrocardiogram and could potentially lead to sudden death. The various impact of different types of pacemakers on life quality and cardiovascular endpoints was shown. Aim. To analyze follow-up cardiovascular endpoints in patients with DSN and installed pacemakers. Material and methods . Six hundred and ten patients with DSN were analyzed in follow-up period (39,7±0,8 months) for unfavorable cardiovascular events (myocardial infarction, strokes, cardiovascular and non-cardiovascular hospitalizations). Results. Mortality rate differed depending on DSN variant (p=0,041), and most unfavorable was “tachy-brady” and sinoatrial node arrest + sinus node block III types. Also, the difference in mortality rate was shown for pacing variants (p=0,049) with maximal rate number of deaths was in ventricular pacemakers (24,6%) less — in dual-chamber pacemakers (11,7%) and minimal — in atrial (5,5%). No changes in cardiovascular endpoints was found between groups with sinus and pacemaker’s rhythm (p&gt;0,5). Conclusion. In the follow-up analyze the difference between cardiovascular endpoints in patients in various types of pacemakers and regimen of stimulation was shown.

Pacing in older people

SummaryThe vast majority of cardiac pacemakers are implanted in older people. Pacing is a safe and effective treatment for patients with symptomatic bradyarrhythmias. This review provides a clinician's guide to the essential aspects of modern pacemaker therapy in older patients, including aetiology and epidemiology of bradycardia. We discuss some barriers to access to pacing. We review indications for pacemakers, and describe pacing system function, including the different types of pacemakers used. We also review clinical outcomes following pacing, follow-up requirements and problems encountered in clinical practice. Finally, we discuss ethical and end of life considerations with these devices.

Norepinephrine Differentially Modulates Different Types of Respiratory Pacemaker and Nonpacemaker Neurons

Pacemakers are found throughout the mammalian CNS. Yet, it remains largely unknown how these neurons contribute to network activity. Here we show that for the respiratory network isolated in transverse slices of mice, different functions can be assigned to different types of pacemakers and nonpacemakers. This difference becomes evident in response to norepinephrine (NE). Although NE depolarized 88% of synaptically isolated inspiratory neurons, this neuromodulator had differential effects on different neuron types. NE increased in cadmium-insensitive pacemakers burst frequency, not burst area and duration, and it increased in cadmium-sensitive pacemakers burst duration and area, but not frequency. NE also differentially modulated nonpacemakers. Two types of nonpacemakers were identified: "silent nonpacemakers" stop spiking, whereas "active nonpacemakers" spontaneously spike when isolated from the network. NE selectively induced cadmium-sensitive pacemaker properties in active, but not silent, nonpacemakers. Flufenamic acid (FFA), a blocker of ICAN, blocked the induction as well as modulation of cadmium-sensitive pacemaker activity, and blocked at the network level the NE-induced increase in burst area and duration of inspiratory network activity; the frequency modulation (FM) was unaffected. We therefore propose that modulation of cadmium-sensitive pacemaker activity contributes at the network level to changes in burst shape, not frequency. Riluzole blocked the FM of isolated cadmium-insensitive pacemakers. In the presence of riluzole, NE caused disorganized network activity, suggesting that cadmium-insensitive pacemakers are critical for rhythm generation. We conclude that different types of nonpacemaker and pacemaker neurons differentially control different aspects of the respiratory rhythm.

Radiation Doses to Patients and Cardiologists from Permanent Cardiac Pacemaker Implantation Procedures

The purpose of this study was to determine the patient and cardiologist doses during the implantation of permanent cardiac pacemakers under fluoroscopic control. For 55 procedures concerning three different types of pacemakers (DDD, VDD, and VVI), the dose-area product (DAP) meter readings and fluoroscopy times were recorded. From these data, the dose to the operating cardiologist was estimated. The median values of DAP and fluoroscopy time for all the procedures monitored were 11.4 Gycm(2) and 6.6 minute, respectively. For the 22 DDD, 21 VDD, and 12 VVI pacemakers implanted, the respective DAP median values were 14.7, 9.9, and 7.3 Gycm(2) and the respective median fluoroscopy times were 8.4, 5, and 2.9 minutes. The median doses to the hands, chest, eyes, and legs of the cardiologist conducting the manipulations were estimated to 0.21, 0.06, 0.03, and 0.11 mGy, respectively, per procedure. Compared to the existing literature, the median DAP value of this study is almost identical to the 11.2 Gycm(2) reported from a sample of 627 patients in 17 different x-ray rooms, whereas the fluoroscopy times are within the range of values reported by other authors. Concerning the cardiologist exposure, the estimated values indicate that the implantation of pacemakers is a procedure that does not involve a severe risk, especially if it is taken into account that lead aprons and collars are routinely used.

Terapia celular: uma nova perspectiva no tratamento da insuficiência cardíaca de causa isquêmica

Millions of people throughout the world have chronic heart failure, with ischemia being one of its most prevalent causes. It is a serious public health problem. The current treatments complementary to the optimized clinical treatment, such as cardiomyoplasty, heart transplantation, and different types of pacemakers, along with mechanical devices of ventricular support have not been established as standard procedures. Each of them has its own disadvantages, creating a field for study and application of alternative techniques. Of the latter, transplantation of exogenous stem cells to the impaired myocardium, aiming at improving cardiac performance, a process called cell cardiomyoplasty, seems to have a promising future 1-3 . Stem cells constitute a population of immature tissue precursor cells capable of self-renewal and production or replacement of cells of many tissues 4 . Different methods of treatment with stem cells have already been or continue to be used, although still in an initial phase of clinical application; a better assessment of the real applicability of stem cells, however, requires long-term results. Currently, the 2 existing types of stem cell therapy aiming at regenerating cardiac muscle or improving its vascularization are as follows: 1) use of embryonic stem cells 5 ; and 2) use of adult .

Permanent pacemaker selection and subsequent survival in elderly Medicare pacemaker recipients.

Dual-chamber pacemakers have been in use for more than 15 years. Although they may confer a physiological advantage over single-chamber ventricular pacemakers, they are more expensive and have a generally shorter service life than single-chamber devices. We carried out the present study to identify patient subgroups who were preferentially receiving greater or lesser proportions of dual-chamber devices and to determine whether the selection of different types of pacemakers was associated with differences in mortality. We analyzed a 20% random national sample of all Medicare beneficiaries aged 65 years or older who underwent initial placement of a permanent pacemaker and were discharged in 1988, 1989, or 1990 (n = 36,312). The minimum follow-up for vital status was 1 year. The relation of pacemaker type to patient and provider characteristics was determined using logistic regression analysis. The relation between pacemaker type and mortality was determined using the Cox proportional hazards method. The proportion of dual-chamber systems that were received increased from 27.2% in 1988 to 37.0% in 1990 (P < .001). Dual-chamber pacemaker recipients were younger (P < .001) than ventricular pacemaker recipients. Other independent correlates of dual-chamber pacemaker selection included male sex (odds ratio and 95% confidence intervals, 1.18 and 1.12 to 1.24, respectively), atrioventricular block (1.59 and 1.51 to 1.67), congestive heart failure (1.14 and 1.08 to 1.20), atrial fibrillation (0.36 and 0.34 to 0.39), and the presence of a major noncardiac diagnosis (0.86 and 0.83 to 0.89). Nonmedical predictors of dual-chamber pacemaker selection included Medicaid eligibility (0.78 and 0.71 to 0.86), implantation in the western United States (1.19 and 1.10 to 1.29), implantation by a rural provider (0.70 and 0.65 to 0.76), hospitalization in a 500-bed-or-larger hospital (1.20 and 1.13 to 1.28), hospitalization in a private hospital (1.19 and 1.10 to 1.28), or hospitalization in a hospital with a catheterization laboratory (1.47 and 1.38 to 1.56). Dual-chamber pacemaker selection was an independent predictor of survival at 1 year (0.82 and 0.77 to 0.87) and at 2 years (0.82 and 0.77 to 0.87) after controlling for potentially confounding patient-level and hospital-level characteristics. The present study describes important variations in the clinical practice of cardiac pacing, many of which are not based on clinical characteristics. Furthermore, the selection of a dual-chamber pacemaker is associated with increased survival. These results underscore the need for prospective, outcome-based clinical trials of pacemaker mode selection.

The effects of electromagnetic fields on cardiac pacemakers

After a brief description of the different types of pacemakers and how they function, the authors address the effects of electromagnetic fields on cardiac pacemakers. The five ways electromagnetic fields can affect pacemakers (temporary inhibition of the pacemaker, temporary function at the fixed noise rate, temporary function at the fixed magnet rate, permanent inhibition or malfunction, and random reprogramming) are discussed. Field experience of one of the co-authors who wears a pacemaker at two Voice of America (VOA) transmitting facilities is described and recommendations are included on safety distances for pacemaker wearers in specific areas of a shortwave and medium wave transmitting facility.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Temporary pacing.

Artificial cardiac pacing, the use of electrical stimuli to cause contraction of heart muscle, is a sophisticated therapeutic and diagnostic tool. Its rapid technologic improvement since first developed in the late 1930’s by Hyman, has made it possible not only to avoid certain cases of death due to heart block, but also to extend and improve the quality of life. Pacemaker therapy is generally used to treat heart rate or rhythm disturbances, being either tachy- or bradyarrhythmias that produce a detrimental drop in cardiac output. Of the many different types of pacemakers and electrodes currently available, ventricular demand pacing is the most commonly used.

Pacemaker-Induced Arrhythmias

The pacemaker ECG with different types of pacemakers used for the treatment of bradyarrhythmias is considered. The arrhythmias induced or interfered with by the pacemakers receive special consideration. The normal function of the most common types of pacing systems is schematically presented.

Types of pacemakers.

To the Editor:— Two different types of pacemakers have been built that avoid competition between the electrical impulse and idiocardiac contractions. One of these is the standby pacemaker (of which there are two models). We had the privilege of publishing our first experience with this pacemaker inThe Journal, and subsequently elaborated on this experience elsewhere.1-3At the same time others developed a pacemaker.4 The article by Goetz (205:657, 1968) as well as your editorial, Apace With Pacemakers, continued to refer to demand pacemakers without reference to standby pacemakers, as if the two were somehow different and unrelated. Despite the slight difference in mode of operation of standby and units, the distinction between them is largely semantic. In both cases a spontaneous idioventricular contraction will affect the next scheduled pacemaker impulse to prevent the implanted pacemaker from firing a stimulus into the vulnerable period of