Implantable cardiac pacemaker: status and future developments (1)

1. introduction

Normally, 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 structure

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 situation

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 House sync touchHair (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 atrioventricular pacing of 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.