Implantable artificial heart pacemaker application and future development

1. Introduction to the normal case, the heart of the sinus node right Atria can automatically, rhythmically emits electrical impulses through cardiac nerve conduction system from different parts of the heart to issue instructions to make myocardial contractility, heartbeat, blood pumping to the whole body. If myocardial nerve conduction system disorder or sinus, atrial sinus knot cannot regularly issued electrical impulses, download electrical pulse, heart arrhythmia occurs, even beating, endangering the lives of patients. Artificial cardiac pacemakers can sick heart as needed according to the need to give a direct electric stimulation, the heartbeat is normal. Pacemaker in form can be divided into external temporary pacing and implantable (or permanent or buried), the former for emergency treatment of temporary pacing, pacing the latter for the long-term. This article primarily discusses implantable artificial heart pacemaker, namely the general sense of the pacemaker. 2. artificial heart pacemaker principle and construct artificial heart pacemaker is a very delicate and reliable with high levels of electrical impulses stimulate is applied must have type of pacemaker pulse generator, and a specially crafted wire (i.e.: pacing catheter electrode) connection, and send electric pulse pacemaker stimulates heart so excited cannot or conduction of cardiac stress and pacing of medical electronic devices. Artificial heart pacemaker mainly consists of two parts: (1) pacing catheter electrode: it will pacemaker output signal lead to myocardial for pacing, on the other hand will feel the heart beat of the signal itself (cavity ECG ICG) feedback to the pacemaker to control the issuance of pacemaker pulse. It is the endocardium electrode, from early development to dual single-pole, or even more extreme. As a long-term pacing catheter electrode must be good with biocompatibility, good toughness, anti aging, corrosion-resistant materials. Electrode wire usually aier near alloy (Elgiloy) or nickel-cobalt-chromium-molybdenum alloy wire-wound into a spiral pipe. Conductor outer insulation materials are selected high-purity silicon rubber or medical polyurethane [3]. Electrode head of materials to surface activation isotropic carbon low temperature pyrolysis or Platinum. (2) pacemaker pulse generator: it consists of pacing circuits, battery and metal casing. Pacemaker energy required is small size, large capacity, slow release energy, sealing performance and reliable battery, at home and abroad the implantable pacemaker commonly used lithium-iodine battery so that the pacemaker continuous life reaches more than 10 years. Since titanium biocompatibility, no rust, so the current pacemaker shell are made from titanium materials stretch forming, ministries to larger circular connection, using laser welding for package [1]. From the 1980s onwards pacing circuit began to manufacture commonly adopted integrated circuit maker main circuit; and CMOS ASIC pacing chip and resistors, capacitors, Reed pipe, and other electronic components together installed on ceramic substrate constitute hybrid (Hybrid) thick film IC as a standard part of pacemaker circuit [3]. 3. artificial heart pacemaker indications (1) height or complete atrioventricular block with Ah-syndrome or syncope episode. Asymptomatic, heart rate less than 50 times/min or QRS spacious malformations and ventricular arrest ＞ 2 seconds as a relative indication. (2) complete or incomplete third bundle branch and double beam branch block with intermittent or paroxysmal complete atrioventricular block, or ventricular rate "4O/min;-bundle branch block with Ah-syndrome or syncope episode; completeness of alternating left and right bundle branch block, his figure confirmed H-V extension. (3) second degree ⅱ atrioventricular block with ' a ' syndrome or syncope episode. Sustained second-degree ⅱ atrioventricular block, ventricular rate less than 5O times per minute without symptoms as relative indications. (4) sick sinus syndrome has the following features: serious sinus bradycardia, ventricular rate "45 times per minute, seriously affect the organ blood supply, heart failure, angina pectoris, dizziness, black; bradycardia, and sinus or sinus room block, r-r interval ＞ 2 seconds with syncope or Al-Syndrome outbreak; bradycardia-tachycardia syndrome have syncope or Al-Syndrome outbreak. (5) use of tachycardia pacemaker or defibrillator, ectopic tachyarrhythmia drug treatment is not valid. (6) recurrent sinus syncope carotid arteries and heart beating. 4. artificial heart pacemaker ' development history and current status of artificial heart pacemaker clinic, the widely used drug for invalid severe arrhythmia patients get treatment, significantly reducing cardiovascular disease mortality, is the modern biomedical engineering for humanity a significant contribution. In 1932, United States of thoracic surgeon Hyman invented the first electric by clockwork-driven pulse generator, with two needle puncture Atrium makes the beating heart complex jumps, he named the artificial heart pacemaker (Artificial Pacemaker), thereby creating an artificial heart pacemaker great era of cardiac arrhythmias. Pacemaker clinic is really used in 1952. United States physician Zoll in vitro pacemakers, carries on the artificial stimulation of the thoracic cardiac pacing, where the two are on the verge of death, heart block, thereby promoting a pacemaker in clinical applications and development. Sweden 1958, 1960, the United States Elmgrist Greatbatch respectively inventions and clinical application of the implantable cardiac pacemaker. From pacemakers to implantable artificial heart pacemaker era, toward the long life, high reliability, lightweight, compact and functional direction. Early pacemaker is natural frequency (or non-synchronous), only rescue and treatment of persistent atrioventricular block, sick sinus syndrome, syndrome, intermittent bradycardia does not apply and cannot be synchronized with the patients own rhythm, ventricular competition occurs causing more serious arrhythmias. To this end, in the mid-1960s has a synchronous pacemakers, which houses the synchronization triggers-(VAT) pacemaker is specifically used to atrioventricular block, and ventricular on-demand (VVI) is at home and abroad the most common cardiac pacemakers. In order for the pacing and cardiac own pacing feature close [1] [3], have appeared in the 1970s and was more in line with the accessory order onwardsBo's dual Chamber pacemaker (DVI), and be able to treat a variety of versatile bradycardia pacemakers (DDD). At this point, the pacemaker's basic treatment has been developed completely. In the 20th century 80 's, the lightening pacemaker in addition, the miniaturization of improvement, a program control and telemetry functions, use external program (Programmer) is available on the implantation of pacemaker for pacing mode, frequency, amplitude, pulse width, perceived sensitivity, refractory period, A-V programmable delay parameter; you can also work on the pacemaker, the status monitor will work parameters, battery consumption, myocardial impedance, information and even the intracardiac ECG, the pacemaker is sent to the external program of Telemetry receiver for display [3]. 1990s, pacemaker and anti-tachycardia and develop better suited to the physiological changes of human activity has made progress, there has been resistance to tachycardia Adaptive pacing and frequency of pacemakers (DDDR), artificial heart pacemaker be dealing with fatal arrhythmia effective weapons. With the development of science and technology, now has more performance of biventricular/double atrial synchronous three Chamber pacemaker and defibrillator function with the pacemaker. 5. artificial heart pacemaker identification code North America pacing and Electrophysiology (NASPE) and the United Kingdom pacing and Electrophysiology Organization (BPEG) to table 1 for the identification of encoding. Generally use the first three identification number recognition pacemaker pacing cavity, the cavity and the perception of perception (P or R-wave, or both) of the response mode. Choose from a fourth location represents one of the two different functions: a program-controlled capacity or frequency Adaptive pacing. P represents the one or two simple programmable function; M-controlled, representing a wide range of features, including models, period, pulse width sensitivity and perception. C indicate information delivery or through one or more of the physiological variables measurement for Adaptive pacing frequency control. The fifth bit indicates special features of tachyarrhythmia: P representative against tachyarrhythmia ventricular pacing, S represents the complex or defibrillation electric shock, d double feature (pacing and shock). In all locations, O specify generic or features are not provided. Table 1: NASPE/BPEG (NBG) pacemaker identification code [2]-the first letter of the second letter of the first three letters of the fourth letter of the first five letters of the classification pacing Chamber perception Chamber response mode programmable frequency response telemetry function of tachycardia and defibrillator function letter v = atrial ventricular A = D = dual Chamber S = single V = A = atrial-ventricular O = no D = dual Chamber S = single I = inhibit T = trigger O = no D = double P = simple programming M = multi-function programmable C = telemetry frequency response R = O = no P = anti-tachycardia pacing S = electrical cardioversion D = P + S 6. artificial heart pacemaker's future after decades of development, the implantable cardiac pacemaker has not only applied to the treatment of heart block, slow-fast syndrome, severe arrhythmia, along with its many new therapeutic effect. These new indications are: orthostatic hypotension, malignant neural cardiac syncope (vasovagal), congenital Q-T interval syndrome and simple PR interval prolongation. They will be the pacemaker application of one of the future direction. A low-power microprocessor chip as a core part of pacemaker circuit, will enable the performance of the pacemaker circuit to modify the software, will change the current full customization (ASIC) design, every improvement is a lot of resources and time, will significantly reduce new pacemaker circuit development cycle and costs. As computer technology, telemetry, the development of new technologies, future may appear fully automated pacemaker. This automation of pulse generator according to patient electrophysiology of basic situation automatically adapt, with time cycle of analysis, sensor input and automatically interpret the stored information to determine the most appropriate pacing mode. Pacemaker to automated determination of atrial and ventricular pacing and perception threshold and, depending on the sensor information automatically programmed basic frequency [4]. 【 References 】 [1] Liu Liang, Gu jiugao. Practical artificial cardiac pacing technology. Nanjing press. 1991.5 [2] corpus luteum steel, etc. Practical cardiac pacing. Tianjin science and technology press. 1993.12 [3] party Sze. Pacemaker technical progress. World medical device. 1998.4 [4] Jihong, Zhang Cheng. Pacemaker's latest progress. Beijing Medical University Press. 2000.9