Cardioversion and defibrillation are therapeutic procedures in which an electric current of a certain intensity is applied directly or through the chest wall to the heart to instantaneously depolarize all or most of the heart muscle in severe tachyarrhythmias, and then the point of highest cardiac autoregulation (usually the sinus node) re-dominates the cardiac rhythm, i.e., by This means that the abnormal heart rhythm is restored to a normal sinus rhythm by means of electrical shocks. Electrical resuscitation is an alternative to drugs and radiofrequency ablation for the treatment of ectopic tachyarrhythmias, and has become the preferred or important treatment for patients with ventricular fibrillation and other tachyarrhythmias because of its rapid action, efficacy, simplicity, and relative safety. The principle and classification of this method is to apply a strong current (currently DC) to the heart for a very short period of time, which causes the majority (more than 75%) of cardiac autoregulatory cells to depolarize at the same time and deactivate all possible foldback channels. Tachycardia terminated by electric shock can be prevented in the long term if the precipitating factors of tachycardia are no longer present, even if the anatomical and electrophysiological basis of the pathogenesis still exists.
Electrical resuscitation is a synchronous instantaneous high-energy discharge to terminate certain ectopic tachyarrhythmias, using its own ECG signal as a trigger marker, whereas electrical defibrillation is an emergency asynchronous instantaneous high-energy discharge to terminate ventricular fibrillation or ventricular flutter.
The difference between electrical resuscitation and electrical defibrillation
1. The indications for treatment are different. Electrical resuscitation is mainly used to treat tachyarrhythmias. The electric defibrillation is only used for the treatment of ventricular fibrillation and ventricular flutter or tachycardia in which the R wave cannot be distinguished.
2. The discharge mode is different. Electric resuscitation is triggered by the patient’s ECG R-wave to synchronize the discharge, and only during the absolute non-response period of the cardiac cycle to avoid inducing ventricular fibrillation, while electric defibrillation is a random non-synchronous discharge mode.
3, the required electric shock energy is different. The energy requirement for electrical resuscitation is generally less than that required for electrical defibrillation.
Types of electric resuscitation (electric defibrillation)
I. Direct current and AC electrical resuscitation (electric defibrillation) can be distinguished into direct current and AC electrical resuscitation (electric defibrillation) according to the nature of the current used. In the early stages of electrical resuscitation, AC electric shock is used to terminate severe tachyarrhythmias. AC electric discharge has a high flow rate and a discharge time of up to 20 ms, which is not easy to avoid the vulnerable period of the ventricle and can easily cause myocardial damage and more serious arrhythmias, especially in vivo AC defibrillation can directly lead to deterioration of cardiac function. Therefore, AC resuscitation (defibrillation) was soon abandoned. In the past 40 years, DC resuscitation has been used worldwide. Compared with AC electrical resuscitation, DC electrical resuscitation is easy to control the discharge volume, safer, and easier to synchronize electrical resuscitation.
Synchronous and non-synchronous electric resuscitation (defibrillation) can be distinguished into synchronous and non-synchronous electric resuscitation (defibrillation) according to whether synchronous triggering is used in the treatment process. Synchronous electrical resuscitation refers to the use of synchronous triggering device to control the release of current pulses by the R-wave of body electrocardiogram, so that the current is released only in the absolute non-response period of the cardiac cycle (the pulse current falls on the descending branch of the R-wave, and avoids falling in the vulnerable period within 20-30ms before the peak of the T-wave) to avoid inducing ventricular fibrillation, which is clinically used for the conversion of tachyarrhythmias other than ventricular fibrillation. The device can be discharged at any time without synchronous triggering and is used to transient ventricular fibrillation or ventricular flutter, which is called asynchronous electrical resuscitation and is usually used clinically only for the resuscitation treatment of ventricular fibrillation or ventricular flutter; there is also rapid ventricular tachycardia in which the R-wave cannot be identified, and because synchronous DC electrical resuscitation is not possible, only asynchronous electrical shock (equivalent to defibrillation) can be used.
According to the position of the electrode plate, it can be divided into in vivo and in vitro electric resuscitation (defibrillation). In vivo electrical resuscitation (defibrillation) is often used in patients undergoing cardiac surgery or emergency open-heart resuscitation, with one electrode plate placed on the right ventricular surface and another plate placed on the apical part of the heart, usually with a current energy of 20-30 J, usually not exceeding 70 J. In non-surgical cases, trans-thoracic wall resuscitation (defibrillation) is mostly used, i.e., external electrical resuscitation (defibrillation); usually APEX (cathode plate) is placed on the left anterior chest or apical part of the heart, and STERNUM (anode plate) is placed on the left anterior chest or apical part of the heart. The APEX (cathodic plate) is usually placed on the left anterior chest or apical region, and the STERNUM (anodic plate) is placed on the right chest or posterior region, thus ensuring that the current can pass right through the heart and achieving the desired defibrillation effect.
Fourth, one-way wave and two-way wave electrical resuscitation (electric defibrillation) According to the different waveforms of defibrillation, modern defibrillators are divided into two types, namely, one-way wave and two-way wave. One-way wave refers to half a positive metaphorical wave, and two-way wave refers to a complete positive metaphorical wave. The advantage of bidirectional wave is that the unidirectional wave ends the cardiac interference clutter and then gives a guiding wave in one direction, which is close to the normal electrical signal of the heart and therefore more effective in stimulating the heart to work normally.
V. Transesophageal low-energy electrical resuscitation requires less energy (20-60J), can be tolerated by patients without anesthesia, and can avoid skin burns, but the design and placement of the esophageal electrode catheter still need continuous improvement, and is expected to become a promising new method for dealing with tachyarrhythmias in the future.
Intracardiac electrical resuscitation via intravenous electrode catheter Usually a quadrupole electrode catheter is used to insert the catheter electrode into the right heart through the anterior elbow or jugular vein under x-ray fluoroscopy. The energy required is usually 2-6 J, which is mostly tolerated by the patient. The initial shock starts with low energy and then gradually increases the electrical energy. It is mainly used for atrial fibrillation that occurs during intracardiac electrophysiological examination.
VII. Implantable cardioverter defibrillator (ICD) In recent years, transvenous placement of endocardial defibrillation electrodes has replaced the early open-heart placement of epicardial defibrillation electrodes. The size of implantable cardioverter defibrillators has been significantly reduced, and they can be embedded between the pectoralis major and minor muscles, or even in a subcutaneous capsule like a pacemaker. It can have the functions of anti-bradycardia pacing, anti-tachycardia pacing, low-energy electrical cardioversion and high-energy electrical defibrillation at the same time.
AED is a computer programmed and controlled, highly automated defibrillator for external electrical defibrillation. Once the electrodes are attached, the rhythm of the cardiac arrest victim is immediately analyzed and the defibrillable rhythm (ventricular fibrillation or pulseless ventricular tachycardia) is quickly identified and determined, and once the defibrillable rhythm is present, the AED advises the operator to perform electrical defibrillation by means of voice prompts and a screen display. Not only professionals, even non-professionals, after the required training hours, can also safely and correctly master the operation of the AED. The operation steps are the same, namely, turn on, analyze the heart rhythm, and recommend whether to shock. Most modern AEDs use two-way wave technology.
Currently, the term electric resuscitation (electric defibrillation) is generally used to refer to the operation of electric shock outside the body using direct current, therefore, the electric resuscitation (electric defibrillation) described below refers to the external DC electric resuscitation (defibrillation).
Indications for electrical cardioversion (defibrillation)
Cardiac electrical resuscitation is particularly effective in the termination of fibrillatory tachycardia. In principle, any form of tachycardia that leads to hypotension, congestive heart failure, or angina pectoris and for which medical therapy is not rapidly effective should be terminated by electric shock. After successful conversion, the patient’s hemodynamic status almost always improves.
Once ventricular fibrillation or ventricular flutter occurs, it usually causes significant hemodynamic disturbances and should be resuscitated immediately with asynchronous shocks, the sooner the better, because the likelihood of successful defibrillation decreases with the passage of time and ventricular fibrillation may turn into cardiac arrest within a few minutes. For patients with intractable ventricular fibrillation, intravenous lidocaine or amiodarone can be pushed if necessary; if the ventricular fibrillation wave is very small before the shock, intravenous epinephrine can be injected to make the fibrillation wave larger in order to improve the success rate of cardioversion.
Second, ventricular tachycardia ventricular tachycardia by drug therapy is ineffective or with serious hemodynamic disorders and frequent As syndrome should be urgent synchronous DC electric shock resuscitation; but for rapid ventricular tachycardia can not identify R wave, sometimes can only carry out asynchronous electric shock resuscitation treatment.
Atrial fibrillation is the most common arrhythmia in which synchronous DC resuscitation is used. The immediate success rate of electrical resuscitation is in the range of 70% to 96%. Because the etiology of atrial fibrillation varies, the duration of the disease varies, and the response to drugs varies greatly, the choice of electrical resuscitation should be weighed in many ways. The following principles should be followed in the treatment of atrial fibrillation: if there is hemodynamic disorder or serious symptoms, but drug therapy is not effective, electric cardioversion is needed as soon as possible; if there is no obvious hemodynamic disorder, emergency electric cardioversion is not needed, but after electric cardioversion, it is expected to maintain sinus rhythm, improve cardiac function and relieve symptoms.
Atrial fibrillation can be considered in the following cases: ① fast ventricular rate, drug therapy is ineffective. (2) Heart failure or angina is worsening or not easily controlled after AF. ③ persistent atrial fibrillation of less than 1 year duration and normal sinus node function before atrial fibrillation. ④The heart and left atrium are not significantly enlarged (cardiothoracic ratio < 60%, left atrial diameter < 55 mm). ⑤ Mitral valve lesions that have been surgically corrected for more than 6 weeks. ⑥Patients whose primary pathology (such as hyperthyroidism, acute myocardial infarction, pneumonia, pulmonary embolism, etc.) has been controlled, but atrial fibrillation still persists. (7) Pre-excitation syndrome combined with rapid atrial fibrillation should be electrically resuscitated as soon as possible if drugs are ineffective and hemodynamic disturbances exist; synchronous DC resuscitation should be considered if the ventricular rate is too fast (>200 beats/min), and when the ventricular rate reaches 250 beats/min, synchronous DC resuscitation is often given immediately.
However, in recent years, there are different opinions on whether to perform electric shock resuscitation by the size of the atria and the severity of the valve lesion, and many clinicians believe that all patients with atrial fibrillation should be given an opportunity for 1 electric resuscitation.
Fourth, atrial flutter atrial flutter drug therapy is usually more difficult, while electrical resuscitation of atrial flutter has a high rate of conversion, the success rate is almost 100%, and the energy required is small, less than 50J energy shock, 95% of patients can be converted to sinus rhythm. Therefore, it has been proposed that electrical resuscitation is the preferred method to terminate atrial flutter, especially in patients with rapid ventricular rate triggering hypotension, heart failure or angina pectoris, which can be immediately synchronized with electrical resuscitation.
Fifth, the majority of paroxysmal supraventricular tachycardia does not require the first choice of electrical resuscitation, should be preferred according to the specific circumstances of the method of excitation of the vagus nerve, or choose the method of drug diversion, can also choose esophageal pacing treatment. However, a small number of intractable paroxysmal supraventricular tachycardia by the above treatment is ineffective, the duration of episodes often, and accompanied by hemodynamic disorders, such as a drop in blood pressure, induced or aggravated angina or heart failure, then either narrow QRS or wide QRS type should be immediately performed direct current cardioversion treatment.
Sixth, ectopic tachycardia of unknown nature ectopic tachycardia of unknown nature (such as supraventricular tachycardia with differential conduction or ventricular tachycardia can not be clearly distinguished) and lead to difficulties in drug use and accompanied by obvious hemodynamic disorders.
Contraindications to electrical resuscitation (defibrillation) are contraindicated in the following cases.
(1) Rapid arrhythmias due to digitalis toxicity. The increased sensitivity of the heart to electric shock during digitalis intoxication can easily lead to the development of malignant ventricular arrhythmias (such as ventricular fibrillation), so that electrical stimulation at this time can cause irreversible cardiac arrest. (ii) Supraventricular arrhythmias with high or complete atrioventricular block or persistent atrial fibrillation in which the ventricular rate is already very slow without the use of drugs affecting atrioventricular conduction. (iii) With pathological sinus node syndrome (i.e., fast-slow syndrome). ④Recent arterial embolism or the presence of intra-atrial thrombus on echocardiography without anticoagulation therapy.
Patients with atrial fibrillation should not undergo electrical resuscitation in the following cases: ①Patients who intend to undergo cardiac surgery in the near future. Electrolyte disorders, especially hypokalemia, should be corrected after electrical resuscitation. (iii) Hyperthyroidism with atrial fibrillation without regular treatment of the former. (iv) Those with severe impairment of left heart function, because of the possibility of acute pulmonary edema after conversion. In addition, those with significantly enlarged heart and atria (cardio-thoracic ratio > 65%, echocardiographic left atrial internal diameter > 55 mm), i.e. successful conversion but unlikely to maintain sinus rhythm. ⑤ Those who have relapsed after resuscitation under maintenance of quinidine or amiodarone or who cannot tolerate maintenance therapy with antiarrhythmic drugs. ⑥Patients with uncontrolled heart disease with rheumatic activity or infective endocarditis. (7) Patients with paroxysmal atrial fibrillation, with few previous episodes of short duration and expected to be spontaneously reversible, because electrical resuscitation does not prevent its recurrence.
In addition, electrical resuscitation should be used with caution in patients with tip-twist ventricular tachycardia or multimodal ventricular tachycardia with hypokalemia and prolonged Q-T interval. The efficacy of electrical resuscitation in tachyarrhythmias due to increased autoregulation at ectopic pacing sites is poor, and even after successful resuscitation, recurrence is easy. Therefore, electric cardioversion is not recommended for atrial tachycardia, non-paroxysmal junctional tachycardia, and accelerated ventricular autonomic rhythm with increased autoregulation.
The indications and contraindications listed above are relative, and the benefits and risks should be evaluated comprehensively in the context of each patient’s specific clinical situation, and should not be generalized.
Common complications
In addition to improper patient selection and handling, complications of electrical resuscitation may be related to pre-existing cardiac disorders and the amount of electrical energy used. The incidence of complications has been reported to be 6% at 150 J and up to 30% at greater than 300 J. Therefore, high energy shocks should be avoided as much as possible.
1. Arrhythmias. (1) common atrial or ventricular premature beats, sinus bradycardia and atrioventricular junctional zone escape, mostly temporary, generally do not need to deal with; (2) sinus arrest, sinus block or atrioventricular block, mostly seen in the original sinus node hypofunction or atrioventricular conduction system has lesions, intravenous isoproterenol or atropine can help improve the ventricular rhythm.
2, myocardial injury after high energy electric shock serum cardiac enzymes (CK, LDH, AST) is elevated, most of them can be normalized in 5-7 days. In a few patients, ST-T changes are seen on the ECG, and occasionally abnormal Q waves and high-potassium T-wave changes are seen.
3, hypotension mostly occurs after high-energy electric shock, which can last for several hours and can recover on its own; if the blood pressure drops significantly, vasoactive drugs such as dobutamine and alamin are available.
4, skin burns almost all patients in the electrode contact site after the electric resuscitation have skin burns, visible local erythema blister, mostly due to electrode plate pressure is not tight conductive paste too little or unevenly coated, generally do not need special treatment.
The incidence of thromboembolism after cardiac electrical resuscitation is about 1.5%, mostly due to peripheral artery embolism caused by dislodged atrial emboli; in patients with a history of repeated embolism in the past, especially in patients with atrial fibrillation, attention should be paid to assessing the need for anticoagulation therapy before resuscitation.
6, pulmonary edema and heart failure due to the suppression of left atrial mechanical function after electrical resuscitation, or pulmonary edema and heart failure due to the influence of pulmonary embolism, can be treated with vasodilators and diuretics, and if necessary, mechanical ventilation therapy.
The energy of electrical resuscitation (defibrillation) is usually expressed in joules, i.e., energy (joules) = power (watts) × time (seconds). The choice of energy size is based on the type of arrhythmia and the condition of the patient. In practice, the patient’s weight and other indicators need to be taken into account, such as lighter weight people can choose a smaller energy, while heavy weight people often need to use a larger energy. In general, the energy for one-way electrical resuscitation (defibrillation) for different arrhythmias is as follows: atrial flutter 50-100 J, atrial fibrillation 100-200 J, supraventricular tachycardia 100-150 J, ventricular tachycardia 100-200 J, ventricular fibrillation 200-360 J. The energy for two-way electrical resuscitation (defibrillation) is often half of the energy for one-way waves. Generally, when a shock does not work, the electrical energy can be increased and shocked again.
Precautions before electrical resuscitation
1.Electrical resuscitation (electric defibrillation) generally requires hospitalization, a comprehensive physical examination and relevant laboratory tests (including electrocardiogram and blood tests, etc.).
2. For those who are on anticoagulation therapy, prothrombin time and activity should be measured. If the patient is taking digitalis-like drugs, they should be discontinued 24 to 48 hours before resuscitation.
3.Fast food and water should be abstained for 8 hours before the electric shock to avoid nausea and vomiting during the resuscitation process.
4, 12-lead ECG recording and continuous ECG monitoring, establishment of intravenous access, terminal oxygen partial pressure of 90% or more.
5.If atrial fibrillation persists for more than 48 hours or the time of atrial fibrillation cannot be determined, routine anticoagulation therapy should be applied before cardioversion. Warfarin should be applied for 3 weeks before resuscitation and continued for 4 weeks after successful resuscitation, and the International Normalized Ratio (INR) should be controlled within the therapeutic range (1.8~3.0).
6. Application of antiarrhythmic drugs before resuscitation: The purpose of taking the drugs is to establish the blood concentration of the corresponding drugs to facilitate the maintenance of sinus rhythm after resuscitation, and to clarify the tolerance of the drugs. In addition, a small number of patients may be able to revert to sinus rhythm and thus avoid electroshock. Commonly used drugs include class Ic and class III antiarrhythmic drugs.
7. During electrical resuscitation (defibrillation), care should be taken that the chest wall between the two electrodes is not coated with conductive substances such as gel, cream or saline, to avoid the possibility of current flowing along the surface of the chest wall without passing through the heart.
Precautions during operation
The room where the electrical resuscitation is administered should be spacious and should have various resuscitation facilities such as oxygen, first aid kit, blood pressure and ECG monitoring equipment in addition to the defibrillator. The patient is placed supine on a hard bed, and the collar and belt are loosened. Fast, safe, and effective anesthesia is generally required to ensure that the patient feels no discomfort or pain during electrical resuscitation and defibrillation, and propofol or midazolam is most often used for direct intravenous injection.
Once the patient is under ideal anesthesia, the chest is exposed, the defibrillator ECG monitoring leads are connected, and the ECG is recorded. And two electrodes coated with conductive paste or wrapped with wet saline gauze were placed in certain positions. One electrode plate was placed between the 2 and 3 ribs of the sternal margin, and the other electrode plate was placed at the apical part of the heart. The distance between the two electrode plates is not less than 10cm, and the electrode plates should be placed close to the skin with certain pressure. When preparing for discharge, the operator should not touch the patient, the bed or the instruments connected with the patient to avoid electric shock.
After successful resuscitation, turn off the power of the defibrillator, clean the electrode plate sufficiently and put it back into the electrode tank.
After electrical resuscitation (defibrillation), cardiac monitoring should be performed immediately after electrical resuscitation, and the patient’s heart rate, heart rhythm, blood pressure, respiration and mental status should be closely observed for 24 hours. Whether there are complications after electrical resuscitation: e.g. skin burns, myocardial injury, circulatory embolism, pulmonary edema, and various forms of arrhythmias.
Patients with ventricular fibrillation are kept in the monitoring unit for observation after resuscitation, and patients with atrial fibrillation and supraventricular tachycardia are kept in the general ward for observation for 1-7 d after resuscitation.
Rest and diet
Patients should rest in bed for l~2d after waking up. Avoid eating and drinking water within 2h of waking up to prevent nausea and vomiting. The amount of activity should be such that it does not cause panic and chest tightness.
Give high-calorie, high-vitamin, easy-to-digest diet after 2h of waking up, keep bowel movement smooth, avoid emotional excitement, smoking, overexertion, and eating stimulating food, etc.
Take medication strictly as prescribed by the doctor and review regularly; if there is panic and chest tightness and dyspnea, consult the doctor immediately. If conditions allow, recurrent ventricular tachycardia and atrial fibrillation should be treated with defibrillation pacemaker or percutaneous catheter radiofrequency ablation as soon as possible.
Patients should be instructed to take medication regularly, informed of the precautions to take medication, avoid triggering factors, maintain a relaxed mood, and increase activities appropriately. Cardiac disease has the possibility of recurrence, and patients are advised to be psychologically prepared.
For patients with atrial fibrillation, even if they are not treated with anticoagulants before resetting, they still need anticoagulation for 4 weeks after resetting, because the recovery of atrial function may be delayed until 3 weeks after the recovery of sinus rhythm.
Steps of extracorporeal electrical cardioversion (defibrillation)
1.Prepare for the operation and prepare various resuscitation equipment and drugs.
2, the patient lies flat on a wooden bed, open the venous access, fully expose the chest wall.
3.Routinely make electrocardiogram before operation. Release the lead wire from the ECG machine after completing the ECG recording to avoid damage to the ECG machine by electric shock. It is also possible to “blind defibrillate” after cardiac arrest, without necessarily delaying defibrillation treatment in order to clarify the type of cardiac arrest.
4. Connect the defibrillator leads, turn on the power, check the synchronization performance, and choose synchronization or non-synchronization according to the actual situation. When synchronization is required, usually choose the lead with higher R-wave for waveform observation.
5. Administer intravenous anesthesia as required. Emergency defibrillation does not require intravenous anesthesia.
6, electrode plate coated with conductive paste or wrapped with saline soaked gauze pad, or even water in case of emergency, but alcohol is absolutely prohibited, otherwise it can cause skin burns.
7.Place the electrode plate as required, avoiding the sternum as much as possible. Press firmly to give a certain pressure to ensure that there is a low impedance, which is conducive to successful defibrillation. Electrode plate position placement: ① anterolateral position (anterior apical position or standard position, for the appropriate default position): one electrode plate is placed under the clavicle of the right anterior chest wall (the second intercostal space on the right edge of the sternum), close to but not overlapping with the sternum; the other electrode plate is placed on the apical (left side of the left nipple, its center is located on the mid-axillary line), and the two electrode plates are at least 10cm apart. ② anterior-left scapular position: one electrode plate is placed under the One electrode plate is placed under the right anterior wall subclavian, and the other electrode plate is placed under the northern left scapula. (③) Anterior-right scapular position (apical posterior position): one electrode plate is placed on the apical part, and the other electrode plate is placed on the right scapular angle behind the patient, taking care to avoid the spine. ④Anterior-posterior position: one electrode plate is placed in the left subscapular region, and the other electrode plate is placed at the fourth intercostal level at the left edge of the sternum.
8.Select the electric energy dose, press the “charge” button, and charge the machine to the corresponding energy. All personnel should not touch the patient, the bed and the instruments and equipment connected with the patient to avoid electric shock.
9, press the “discharge” button, when you observe the electrode plate discharge, then release the button, release the electrode plate.
10.After the electric shock, immediately listen to the heart and observe the patient’s electrocardiogram, observe whether the resuscitation or defibrillation is successful and decide whether the electric resuscitation or defibrillation is needed again.
11.Conventional lead electrocardiogram is performed immediately after the electric shock, and monitoring of ECG, blood pressure, respiration and consciousness is usually required for continuous ld.
12, In ventricular fibrillation, no preoperative preparation is made, no anesthesia is required, and asynchronous electroshock defibrillation is performed as soon as possible.
Electrical resuscitation (electrical defibrillation) in special cases
1. Patients after pacemaker implantation: Pacemakers mostly apply Zinner diodes to protect the pacemaker circuit. When high-energy electricity is sensed the diode switch closes to produce a short circuit, enabling the pacemaker to tolerate 400 J of electrical energy at a distance of 2 to 4 inches from the pacemaker. However, if the electrode plate is placed too close to the pacemaker, there is a risk of elevated pacemaker thresholds, acute or chronic perceptual impairment, pacemaker frequency spiking, reversible or irreversible microprocessor programming changes, etc. While previous guidelines recommended that electrode pads be placed at least 2.5 cm from the pacemaker, recent guidelines emphasize that placement of electrode pads or electrode plates should not result in delayed defibrillation and that placing electrode pads or plates directly on top of the implanted device should be avoided. Therefore, the following measures should be taken when performing electrical resuscitation (defibrillation) in patients with pacemakers: use the lowest possible effective electrical energy; place the electrode plate at least 10 cm from the pacemaker (domestic empirical practice); try to place the electrode plate in anterior-posterior position; test the pacemaker function immediately after the shock and reprogram the pacemaker.
2. Electrical cardioversion (defibrillation) during pregnancy: A variety of tachyarrhythmias may occur during pregnancy, sometimes requiring electrical shock therapy. The electrical energy that reaches the fetal heart during electrical cardioversion (defibrillation) is very small and the chance of causing fetal ventricular fibrillation is very low. There are reports of pregnant women who have been treated with multiple high-energy electrical resuscitations and delivered normal babies, both nationally and internationally. This suggests that electrical resuscitation (defibrillation) during pregnancy is safe. However, the fetal electrocardiogram should still be tested when performing electrical resuscitation, and a low and effective electrical energy should be chosen as much as possible.
3, arrhythmia caused by digitalis poisoning: in principle, electric resuscitation (electric defibrillation) treatment is contraindicated when digitalis poisoning, however, if the rapid arrhythmia with serious hemodynamic disorders need to contraindicate electric resuscitation (electric defibrillation), it should start with low electric energy (5J), and gradually increase the electric energy when it is ineffective, if necessary, intravenous lidocaine or phenytoin sodium can be injected before resuscitation to minimize or avoid serious ventricular arrhythmias. If necessary, intravenous lidocaine or phenytoin sodium can be given before resuscitation to minimize or avoid severe ventricular arrhythmias.