Lesson topic №25. Нарушения ритма (Cardiac arrhythmia in the outpatient setting)
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Supraventricular tachycardia: postural orthostatic tachycardia syndrome
POTS is defined as a clinical syndrome usually characterized by an increase in heart rate of ≥30 b.p.m. when standing for >30 s (or ≥40 b.p.m. in individuals aged 12 − 19 years) and an absence of orthostatic hypotension (>20 mmHg drop in systolic blood pressure).
POTS is diagnosed during a 10 min active stand test or head-up tilt test with non-invasive haemodynamic monitoring.
The evaluation of a patient suspected of having POTS should eliminate other causes of sinus tachycardia such as hypovolaemia, anaemia, hyperthyroidism, pulmonary embolus, or pheochromocytoma.
Supraventricular tachycardia: postural orthostatic tachycardia syndrome
Non-pharmacological treatments should be attempted first in all patients.
These include withdrawing medications that might worsen POTS, such as norepinephrine transport inhibitors, increasing blood volume with enhanced salt and fluid intake, reducing venous pooling with compression garments, and limiting deconditioning.
To reduce unpleasant sinus tachycardia and palpitations, low-dose propranolol [10–20 mg per os (p.o.)] acutely lowers standing heart rate and improves symptoms in patients with POTS, while higher doses of propranolol are less well tolerated.
Ivabradine slows sinus rates without affecting blood pressure, and in an openlabel study 60% of patients with POTS had symptomatic improvement.
Supraventricular tachycardia: focal atrial tachycardia
Focal AT is defined as an organized atrial rhythm ≥100 b.p.m. initiated from a discrete origin and spreading over both atria in a centrifugal pattern.
Symptoms may include palpitations, shortness of breath, chest pain, and rarely syncope or presyncope.
P wave identification from a 12 lead ECG recording during tachycardia is critical. Depending on the AV conduction and AT rate, the P waves may be hidden in the QRS or T waves.
Focal AT may arise from any site in both atria, but particular sites of predilection in the normal heart rate are the crista terminalis, the tricuspid and mitral valve annulus, and within the thoracic veins joining the atria.
Supraventricular tachycardia: focal atrial tachycardia
Focal atrial tachycardia. (A) Focal atrial tachycardia originating at the lateral right atrium conducted initially with full and then incomplete right branch bundle block aberration. (B) Focal atrial tachycardia originating at the left atrium (left superior pulmonary vein). (C) Focal atrial tachycardia from the right atrial appendage.
Supraventricular tachycardia: focal atrial tachycardia
Аcute therapy may be initiated with beta-blockers or calcium channel blockers, which may terminate focal ATs or slow the ventricular rate.
Adenosine may terminate AT.
Class IA, IC, and III drugs may also be effective.
Amiodarone may also be used for cardioversion or slowing of the ventricular rate.
Catheter ablation is the treatment of choice for recurrent focal AT, especially for incessant AT.
As a chronic therapy may be effective beta-blockers and calcium channel, and there is a low risk of side effects.
Ivabradine may also be effective in focal AT, and ideally should be given with a beta-blocker.
Supraventricular tachycardia: multifocal atrial tachycardia
Multifocal AT is defined as a rapid, irregular rhythm with at least three distinct morphologies of P waves on the surface ECG.
Multifocal AT is commonly associated with underlying conditions, including pulmonary disease, pulmonary hypertension, coronary disease, and valvular heart disease, as well as hypomagnesaemia and theophylline therapy.
The first-line treatment is management of the underlying condition.
Antiarrhythmic medications, in general, are not helpful in suppressing multifocal AT. Beta-blockers, or non-dihydropyridine calcium channel blockers should be considered
Supraventricular tachycardia: multifocal atrial tachycardia
It may be difficult to distinguish multifocal AT from AF on ECG.
Unlike AF, there is a distinct isoelectric period between visible P waves.
The PP, PR, and RR intervals are variable.
Supraventricular tachycardia: typical atrial flutter
Typical atrial flutter: common (counter-clockwise) and reverse (clockwise).
In counter-clockwise flutter, the circuit results in regular atrial activation from 250–330 b.p.m., with negative saw-tooth waves in inferior leads and positive waves in V1.
In clockwise flutter, ECG flutter waves in inferior leads look positive and broad, and are frequently bimodal negative in V1.
Supraventricular tachycardia: typical atrial flutter
Counter-clockwise (A) and clockwise
(B) atrial flutter with 2:1 atrioventricular conduction.
Supraventricular tachycardia: typical atrial flutter
Synchronized cardioversion is recommended for haemodynamically unstable patients.
Beta-blockers or non-dihydropyridine calcium channel blockers (verapamil or diltiazem), should be considered for control of rapid ventricular rate.
Amiodarone may be tried.
Anticoagulation, as in AF, is recommended for patients with atrial flutter and concomitant AF. Patients with atrial flutter without AF should be considered for anticoagulation.
Catheter ablation is the most effective therapy to maintain sinus rhythm.
When ablation is not feasible or the patient’s preference, antiarrhythmic drugs may also be used to maintain sinus rhythm (sotalol, amiodaron).