It is commonly seen in the absence of organic heart disease. The tachycardia starts and stops abruptly. In mild cases, patients may experience palpitations and chest tightness, while in severe cases, hemodynamic disturbances can lead to dizziness or even loss of consciousness.

bubble_chart Diagnosis

(I) Medical history and symptoms: The symptoms have a sudden onset and termination, can be induced by exercise or emotional agitation, and often have a history of recurrent episodes. The medical history should inquire whether electrocardiogram (ECG) examinations have been performed in the past, the results of such examinations, the ECG manifestations during non-attack stages, whether medications such as verapamil or cedilanid have been used, and their efficacy.

(II) Physical examination findings: During an episode, the heart rate is mostly between 160-240 beats per minute, rapid and regular, with strong heart sounds, and usually no heart murmurs; blood pressure is normal or slightly low.

(III) Auxiliary examinations: ECG can confirm the diagnosis. The QRS waves are supraventricular in shape, rapid and regular. In cases of atrioventricular reentry (including overt and concealed pre-excitation syndromes), retrograde P' waves are often seen after the QRS waves, whereas in atrioventricular nodal reentrant supraventricular tachycardia, no P' waves are observed after the QRS waves. When there is antegrade conduction via an accessory pathway in pre-excitation syndrome or when supraventricular tachycardia is accompanied by bundle branch block, the QRS waves during tachycardia are wide and bizarre. Esophageal pacing can induce supraventricular tachycardia in most patients, confirm the diagnosis, and provide preliminary classification.

bubble_chart Treatment Measures

For patients without hemodynamic instability, vagal stimulation or intravenous medication can be chosen to terminate supraventricular tachycardia (SVT). Methods of vagal stimulation include:

(1) Stimulating the uvula to induce nausea and vomiting;

(2) Holding breath after deep inspiration (Valsalva maneuver). Without professional guidance, carotid sinus massage and ocular pressure are not recommended. For patients without heart failure, verapamil 5mg diluted and slowly injected intravenously is the first choice. If ineffective, additional doses may be given, with a total dose generally not exceeding 15mg. For patients with heart failure, cedilanid is preferred, with an initial dose of 0.4mg diluted and slowly injected intravenously. If ineffective, an additional 0.2mg may be given after 2 hours, with a total dose not exceeding 1.2mg within 24 hours. Rapid intravenous injection of ATP 20mg can terminate SVT, but it is contraindicated in elderly patients and those with sick sinus syndrome. Intravenous injection of propafenone 75mg or amiodarone 150mg can also terminate SVT episodes. If medication fails to terminate the episode, rapid transesophageal atrial pacing may be used. For patients with hemodynamic instability or when the above methods are ineffective, synchronized direct current cardioversion is an option, with an energy level of 100–200 joules, but it is contraindicated in cases of digitalis toxicity or hypokalemia. Catheter radiofrequency ablation can effectively cure paroxysmal supraventricular tachycardia.