ICD implantation

Sudden cardiac death has become an important issue in cardiac emergencies. It is reported that in the United States alone, about 400,000 to 600,000 people die of sudden cardiac death each year, of which more than 80% occur in patients with coronary heart disease; 80% to 90% are caused by ventricular tachycardia or ventricular fibrillation. About 140,000 people die each year from sudden cardiac death in China. Most sudden deaths occur outside the hospital or clinic. About one-third of the patients die from a few minutes to a few hours after the onset of the disease, making it difficult to transport to a medical unit for treatment. The direct cause of most cardiac deaths is ventricular fibrillation, not cardiac arrest. Ventricular tachycardia occurs before ventricular fibrillation, and it is difficult to detect because the onset of ventricular tachycardia is extremely transient and turns into fatal ventricular fibrillation. 20% to 25% of patients with coronary heart disease are ventricular tachycardia or ventricular fibrillation as the first clinical manifestation of coronary heart disease. Large-scale clinical trials have confirmed that patients with coronary heart disease or old myocardial infarction, frequent premature ventricular (10/h), and decreased left ventricular ejection fraction have a two-year mortality rate of 30%. Multicenter studies have shown that a buried cardioverter defibrillator (ICD) has a significant effect in preventing sudden death due to ventricular tachycardia and/or ventricular fibrillation (VI/VF). In 1980, Miroski and Mower first applied ICD to the clinic. The clinical ventricular tachycardia or ventricular fibrillation ability has been well documented by clinical studies of ICD recognition and conversion or defibrillation. In the early 1990s, several multicenter trials compared ICD and drug therapy in high-risk patients. These prospective randomized, multicenter trials clearly demonstrate that ICD significantly reduces the overall mortality and sudden death rates in patients at risk of sudden arrhythmogenic death, and suggests that ICD should be the first choice for treatment of malignant arrhythmias. Since the application of the ICC system via the venous chest in 1996, China has developed rapidly. By the end of 2000, ICD has been implanted in 208 patients, including dual-chamber ICD. However, compared with developed countries, the number of implants still has a large gap. With the continuous development of China's economy and the continuous promotion of ICD technology, ICD treatment will enter a stage of rapid development in China in the near future. The design and development of ICD has gone through three stages. The first stage of ICD only performs a charge-discharge defibrillation response to ventricular arrhythmia. The second phase of ICD has added the programmatic features of many projects, even with anti-bradycardia support pacing. The third phase of the ICD has added an anti-tachycardia stimulation program. The latter treats rapid ventricular arrhythmia with a level of treatment. For ventricular tachycardia, first-ever anti-tachycardia stimulation, ineffective and/or conversion to ventricular fibrillation, a low-energy electric shock is applied. High-energy first-aid shocks, when the heart rate is too slow, pacing as needed. In addition, ICD has an information storage function that stores patients with ventricular arrhythmia for later analysis. In addition, dual-chamber ICD (DDD-ICD) has also been clinically applied. The dual-chamber ICD increases the atrial electrode to more effectively separate the upper chamber and ventricular tachycardia, and can perform anti-tachycardia pacing therapy at room rate and provides a dual-chamber pacing system. All of these treatments can be selected and parameterized by in vitro programming. The products equivalent to these three stages are called the first, second and third generation ICDs. The 3rd generation ICD is composed of a pulse generator and a wire electrode. The wire electrode is implanted intravenously, with a bipolar configuration consisting of a right ventricular electrode and a separate annular electrode to sense heart rate. Some transvenous electrodes have two defibrillation electrodes, and an electric shock is made between the two electrodes. A subcutaneous sheet electrode or a subcutaneous electrode array may be added when the defibrillation threshold of the transvenous electrode is too high. At present, the clinical application of ICD has the function of identifying and treating tachyarrhythmia and bradycardia regardless of the model, and all use the transvenous electrode and the chest wall. In 1993, the US FDA officially approved the third-generation non-open chest ICD system. Since 1994, the intravenous monopolar defibrillation system has been used in clinical applications. Currently, ICD implantation surgery is similar to cardiac pacemaker implantation. The difference is that ventricular fibrillation is required to test the defibrillation threshold during ICD implantation. The future ICD will develop in a multi-functional direction, from the current single rapid ventricular arrhythmia treatment to various arrhythmias, including rapid ventricular, atrial arrhythmia, slow arrhythmia, heart failure and other treatment development. This multi-function therapy device will increase the intracardiac electrode wire to 3 to 4 and become a 3-cavity or 4-cavity ICD. For patients with heart failure and indoor block, biventricular ventricular 3-cavity ICD can be used to treat arrhythmia, and double ventricle can improve heart function. For patients with IBD and intraventricular conduction delay, ICD patients need to be implanted. Double-chamber 3-cavity ICD can be used. In addition to ventricular and atrial defibrillation, dual-compartment synchronized pacing can also prevent the occurrence of atrial fibrillation. In addition, this versatile device will be equipped with a drug delivery system that prevents the occurrence of atrial, ventricular tachyarrhythmia and adjuvant treatment of heart failure. Treatment of diseases: heart disease myocardial infarction Indication ICD implantation is suitable for: 1. Class I clear indications (1) Cardiac arrest caused by ventricular fibrillation or ventricular tachycardia caused by non-transient or reversible causes. (2) spontaneous persistent ventricular tachycardia. (3) patients with unexplained syncope, cardiac electrophysiological examination can induce continuous ventricular tachycardia or ventricular fibrillation, and drug treatment is ineffective or intolerant. (4) Non-sustained ventricular tachycardia caused by old myocardial infarction with left heart failure (left ventricular ejection fraction <0.35), cardiac electrophysiological examination can induce continuous ventricular tachycardia or ventricular fibrillation, can not be classified by type 1 anti-heart rhythm Inhibitors of abnormal drugs. 2. Class II relative indications (1) Congenital long QT syndrome or other familial hereditary diseases such as arrhythmia caused by right atrial dysplasia, Brugada syndrome, etc. caused by drugs can not effectively control malignant arrhythmias. (2) Old myocardial infarction or cardiomyopathy combined with non-sustained ventricular tachycardia caused by left heart failure, cardiac electrophysiological examination can induce continuous ventricular tachycardia or ventricular fibrillation. Contraindications 1. Failure to confirm recurrent episodes of ventricular tachycardia or ventricular fibrillation. 2. Endless ventricular tachycardia or ventricular fibrillation. 3. Persistent ventricular tachycardia that can be treated by surgery or catheter ablation, such as idiopathic ventricular tachycardia, bundle reentrant ventricular tachycardia, and the like. 4. Rapid arrhythmia caused by transient or reversible factors. 5. End-of-life disease with a life expectancy of 6 months. 6. A significant mental disorder that may be exacerbated by instrument implantation or that cannot be systematically followed up. 7. Coronary heart disease patients with left ventricular dysfunction and QRS widening, but no spontaneous or induced persistent or non-sustained VT, who are preparing for emergency coronary artery bypass surgery. 8. Cardiac function grade IV, drug-refractory congestive heart failure, non-heart transplantation candidates. Preoperative preparation Pouch production If the ICD is large, it is advisable to make the pouch between the pectoralis major and the pectoralis minor muscles in order to avoid damage to the skin. For the defibrillation electrode without the case, the bag can be done on the left chest or the right chest; the ICD is used as a defibrillation electrode, and the left chest is suitable. 2. Insert wire electrode Puncture the subclavian vein (or the beginning of the vein) into the wire electrode in the incision, apex to the right ventricular apex, so that the distal end of the wire spring electrode in the right ventricular cavity is as long as possible, so that the current is more during the electric shock Cover the myocardium and improve the efficacy. 3. Electrode test Electrode testing includes R wave amplitude, pacing threshold, shock impedance and defibrillation threshold. The R wave amplitude is required to be 5 mV or more, the pacing threshold is required to be <1.0 V, and the impedance is between 300 and 1200 . If the R position of the electrode position is still not met, a spiral electrode wire is required. After the above test meets the requirements, the wire is fixed and the defibrillation threshold (DFT) is determined. Determining DFT involves two steps of inducing ventricular fibrillation and defibrillation. There are two ways to induce ventricular fibrillation, one is a low-energy T-wave synchronous shock, and the other is an alternating current stimulus. T-wave synchronous electric shock is generally preferred, and unsuccessful ones switch to alternating current stimulation. Ventricular fibrillation is induced by a T-wave synchronized shock or alternating current with a stimulation interval of 50 (or 30) ms, and then tested for DFT. The successful defibrillation output energy requirement is at least 10 times lower than the ICD defibrillation maximum output energy. If the defibrillation threshold is not met, a subcutaneous chip electrode or a skin array electrode should be added. At present, the maximum shock energy of most ICDs is 34J, so the DFT 24J meets the requirements. Before the induction of ventricular fibrillation, it is necessary to prepare for external defibrillation. The advantage of using non-hand-held defibrillator is that it does not destroy the aseptic conditions, does not need to move the X-ray head, defibrillation is rapid, and can be operated step by step after defibrillation. Local anesthesia patients with diazepam 20 ~ 30mg before induced ventricular fibrillation, so that patients sleep deeply. 4. Suture incision The incision can be sutured after the DFT meets the requirements. If the DFT is measured by ECD, the simulator should be taken out, and then the ICD should be placed in the capsular bag, and the suture should be fixed through the small round hole at the upper edge of the ICD to the pectoralis major muscle at the upper edge of the capsular bag to avoid displacement. Close the ICD diagnostic/treatment procedure and suture the muscles, subcutaneous tissue and skin layer by layer. 5. Set and enter working parameters After the incision is completed, you need to reset and input the ICD working parameters. In fact, when determining the DFT, it is also necessary to set and input the working parameters. Since the setting principles are the same, in order to avoid repetition, the general steps are as follows: (1) Set the working area: According to the patient's rapid arrhythmia attack and treatment characteristics, set up 2 to 3 working areas (one ventricular fibrillation area, 1 to 2 ventricular rate areas). (2) Setting up a rapid arrhythmia diagnostic program 1 Set the frequency threshold for each work area. The ventricular fibrillation area is generally 200-250 times/min. The frequency threshold of ventricular tachycardia is 10-20 times lower than the frequency of clinical episodes, and the frequency difference between the two ventricular tachycardia regions is at least 20 times/min. 2 set the duration of ventricular fibrillation and ventricular tachycardia, the initial recognition time of ventricular fibrillation is set to 18/24 or 12/16 cardiac cycles or within 5 s; re-identification is shorter than the initial recognition, can be set to 9/12. Usually, the ventricular tachycardia duration is 16 to 20 cardiac cycles or within 5 s. 3 sudden and stable standards, prone to tachycardia add sudden standards, a history of atrial fibrillation plus stability standards. 4 Set the re-identification criteria, the arrhythmia duration should be shorter than the initial recognition time. (3) setting up a rapid arrhythmia treatment program 1 ventricular fibrillation can only be cardioversion, the first shock energy is 5~10J higher than DFT. For safety reasons, the maximum energy (30~34J) will be used from the 2nd start, and the last 1 or 2 times can be used to modulate the electric shock. Sex. 2 ventricular tachycardia is generally treated with ATP-low-energy electric shock-high-energy electric shock ladder method. ATP: The ventricular tachycardia of 180 times/min or less is terminated by the ATP method. The pacing cycle can be started with a short burst. The pacing circumference starts from about 80% of the circumference of the tachycardia, 4 to 10 per burst. Pulse, the array is decremented by 10ms, the minimum perimeter is limited to 200ms, and a total of 4 to 5 arrays are set. The second set of ATP procedures can use the pacing mode with decreasing circumference. The pacing circumference starts from 90% of the circumference of the tachycardia. Each burst has 3 to 4 pulses, and a total of 3 to 4 arrays are set. Can be decremented by 10ms. Electric shock: After the program is placed in ATP, the first energy is 1~10J, the second time is 5~10J, and the third energy is available for the third time. The ATP parameters and shock energy are preferably set with reference to preoperative or intraoperative electrophysiological findings. (4) Set the parameters of bradycardia pacing work. (5) Set the information storage working parameters. ECG storage consumes more power. When the storage volume is large, it affects the ICD life (note the prompts in the programmer), but at least the ECG before each episode of tachyarrhythmia, the episode and the termination process should be stored in order to analyze the seizure pattern and adjustment. Working parameters. After the work program is input, the result is printed and confirmed.

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