Lesson topic №25. Нарушения ритма (Cardiac arrhythmia in the outpatient setting)
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Supraventricular tachycardia: acute management
Narrow QRS (≤120 ms) tachycardias
Supraventricular tachycardia: vagal manoeuvres
Vagal manoeuvres can be used to terminate an episode of narrow QRS SVT.
Vagal manoeuvres include different techniques used to stimulate the receptors in the internal carotid arteries.
The Valsalva manoeuvre is a safe and internationally recommended first-line emergency treatment for SVT.
A modified approach to the Valsalva manoeuvre provides a considerable enhancement of conversion success rates. This enhanced method requires the Valsalva to be completed semi-recumbent, with supine repositioning and passive leg raise after the Valsalva strain. Blowing into a 10 mL syringe with sufficient force to move the plunger may standardize the approach.
Carotid sinus massage is performed with the patient’s neck in an extended position, with the head turned away from the side to which pressure is applied. It should always be unilateral as there is a potential risk with bilateral pressure, and it should be limited to 5 s.
Other manoeuvres, such as facial immersion in cold water or forceful coughing, are rarely used now.
Supraventricular tachycardia: The Valsalva manoeuvre
Patients blew into a syringe for 15 seconds and remained in the same position for 45 seconds.
In the modified Valsalva patients at the end of the strain were laid flat with their legs raised to 45° for 15 seconds.
Supraventricular tachycardia: acute management
Wide QRS (>120 ms) tachycardias
Supraventricular tachycardia: sinus tachycardia
Sinus tachycardia is defined as a sinus rate >100 b.p.m. On the ECG, the P wave is positive in leads I, II, and aVF, and biphasic/negative in lead V1.
Supraventricular tachycardia: sinus tachycardia
The determinants of physiological sinus tachycardia are, by definition, physiological (effort, stress, or pregnancy), and may also arise secondary to other medical conditions or drugs.
Physiological sinus tachycardia is treated by identifying and eliminating the cause.
Inappropriate sinus tachycardia is defined as a fast sinus rhythm (>100 b.p.m.) at rest or minimal activity that is out of proportion with the level of physical, emotional, pathological, or pharmacological stress.
The underlying mechanism of inappropriate sinus tachycardia remains poorly understood and is likely to be multifactorial (e.g. dysautonomia, neurohormonal dysregulation, and intrinsic sinus node hyperactivity).
Supraventricular tachycardia: sinus tachycardia
Patients with inappropriate sinus tachycardia have a wide spectrum of clinical presentations ranging from usually asymptomatic or minimally symptomatic palpitations to dyspnoea, exercise intolerance, dizziness, and lightheadedness.
The diagnosis of inappropriate sinus tachycardia is one of exclusion of postural orthostatic tachycardia syndrome, sinus re-entrant tachycardia, or focal atrial tachycardia from the superior part of the crista terminalis or right superior pulmonary vein.
Supraventricular tachycardia: sinus tachycardia
Supraventricular tachycardia: sinus node reentrant tachycardia
On the ECG, the polarity and configuration of the P waves are similar to the configuration of sinus P waves.
Supraventricular tachycardia: sinus node reentrant tachycardia
Sinus node re-entrant tachycardia arises from a re-entry circuit involving the sinus node and, in contrast to IST, is characterized by paroxysmal episodes of tachycardia.
This uncommon arrhythmia may be associated with paroxysmal symptoms of palpitation, dizziness, and light-headedness.
The diagnosis of sinus node re-entrant tachycardia is suspected on ECG and Holter ECG.
Verapamil and amiodarone have demonstrated variable success, whereas beta-blockers are often ineffective.
Sinus node reentrant tachycardia may be effectively and safely treated with catheter ablation.