Torsades de pointes (TdP) is a special type of ventricular arrhythmia, so named because its waveform twists around the baseline. Common in patients with delayed Q-T interval of the electrocardiogram, the etiological factors include hypokalemia, severe bradycardia and genetic factors, which can be induced by drugs. Torsades de pointes can easily be caused by taking certain drugs in the presence of electrolyte disturbances (hypokalemia, hypomagnesemia). The mechanism It is related to cardiac conduction reentry, caused by slow conduction of ventricular cells and inconsistent ventricular repolarization. Often repeated attacks, and easy to develop into ventricular fibrillation and death. 01. The main drug that triggers TdP1. Antiarrhythmic Drugs (quinidine, procainamide, etc.) sodium channel blockers Class IA antiarrhythmic drugs have serious cardiotoxicity. Interval prolongation, high concentrations can cause atrioventricular block. 2. Diuretics (indapamide, hydrochlorothiazide, etc.) The degree of serum potassium reduction was positively correlated with the patient’s baseline serum potassium level and diuretic dosage. Hypokalemia is one of the dose-related adverse reactions of thiazide diuretics, which can lead to malignant arrhythmia and even sudden cardiac death in severe cases. Combined use with potassium-sparing diuretics can reduce the occurrence of hypokalemia. 3. β-receptor blockers (sotalol, etc.) The adverse reactions of sotalol are generally related to its β-receptor blocking effects, such as bradycardia, hypotension, bronchospasm, etc. . The prolongation of the Q-T interval of the electrocardiogram is related to the blood drug concentration. If the dose is large and the blood drug concentration is high, TdP can be induced. Therefore, attention should be paid to the ECG monitoring during the drug use, and the combination of potassium-scavenging diuretics should be avoided. 4. Lipid-lowering drugs (probucol, etc.) The most common adverse reactions of probucol are gastrointestinal discomfort, including abdominal distension, epigastric pain, diarrhea, occasional headache, dizziness and paresthesia, etc. These side effects generally do not affect the continuation of the medication, and tend to decrease with the prolongation of the medication time, and disappear after the withdrawal of the medication. But in addition, probucol can cause electrocardiogram Q-T interval prolongation, torsades de pointes and other serious adverse reactions. Therefore, the State Food and Drug Administration recently revised the instructions for probucol to clearly stipulate It is contraindicated in the following situations:
① Recent myocardial damage, such as recent myocardial infarction;
② Severe ventricular arrhythmia, bradycardia;
③ Cardiogenic syncope Or those with unexplained syncope;
④ Those with Q-T interval prolongation;
⑤ Those who are taking drugs to prolong the Q-T interval;
⑥ Complicated with low blood pressure Potassium or low blood magnesium.
And during the medication period, the Q-T interval of the electrocardiogram should be checked regularly, and hypokalemia and hypomagnesemia should be corrected in time. Once the prolongation of the Q-T interval is found, it is necessary to carefully determine whether to continue the medication.
5. Quinolones (ciprofloxacin, ofloxacin, levofloxacin, gatifloxacin, moxifloxacin, etc.) quinolones can cause The prolongation of the Q-T interval of the electrocardiogram induces TdP. The degree of Q-T interval prolongation is closely related to the plasma concentration of the drug (≥ 1000 ng/mL). and excretion. 6. Macrolides (erythromycin, clarithromycin, azithromycin, roxithromycin, etc.) Rapid intravenous infusion of macrolides can cause cardiotoxicity, The main manifestations are abnormal ECG repolarization, arrhythmia, prolongation of Q-T interval and induced TdP, and even sudden death. Therefore, during the medication period, attention should be paid to the relevant ECG changes. Once any abnormality caused by the drug is found, the drug should be stopped in time or emergency measures should be taken. 7. Prokinetic drugs (cisapride, domperidone, etc.) Domperidone is mainly metabolized by CYP3A4, which can cause mild prolongation of the electrocardiogram Q-T interval. 8. 5-phosphodiesterase inhibitors (sildenafil, tadalafil, etc.) have the risk of inducing heart disease and should be contraindicated in high-risk groups. 9. Antihistamines (astemizole, ebastine, terfenadine, loratadine, diphenhydramine, etc.)10 . Antipsychotics (clozapine, olanzapine, quetiapine, risperidone, droperidol, haloperidol, clomipramine, thioridazine, etc.)02. Acute management of the occurrence of TdP The first step is to discontinue all drugs that can prolong the Q-T interval and correct the relevant factors.
1. If torsades de pointes ventricular tachycardia cannot be terminated on its own, accompanied by hemodynamic instability, or even worsened to ventricular fibrillation, electrical defibrillation should be performed immediately.
2. If long Q-T interval syndrome cannot be identified early, that is, when the first symptom is ventricular tachycardia, the electrocardiogram should be strictly identified. Identify whether it is TdP. ① When torsades de pointes ventricular tachycardia occurs and can be self-terminating and recurring, the first choice is magnesium sulfate intravenous push;2 If the response is poor and bradycardia is present, add isoproterenol or atropine to increase the heart rate and shorten the Q-T interval. When the vital signs are stable, a temporary pacemaker can be implanted in time, and the start heart rate > 70 beats/min; ③ If the attack persists, lidocaine or phenytoin may be added. 3. It is recommended to maintain serum potassium level of 4.5-5.0 mmol/L and serum magnesium level ≥ 2.0 mmol/L.
Summary① Avoiding the application in high-risk patients as much as possible can prolong the Q-T interval ② Regular monitoring of serum potassium and magnesium, and correction with potassium chloride, magnesium sulfate or potassium magnesium aspartate if necessary;< span>③ Elderly and female patients may have longer Q-T interval, and special attention should be paid to drugs that cause Q-T interval prolongation. Planning: lySubmission: [email protected]Source of title map: Zhanku Hailuo