p.10 抽出テキスト

............................................................................................................ 5 Cardiac anatomy for the electrophysiologist

Knowledge of anatomical structures inside and outside the atrial chambers is of clinical importance, especially when interventional procedures are being considered. A detailed discussion is provided in the Supplementary Data.

6 Epidemiology of

supraventricular tachycardia

Epidemiological studies on the SVT population are limited. In the general population, the SVT prevalence is 2.25/1000 persons and the incidence is 35/100000 person-years. Women have a risk of developing SVT that is two times greater than that of men, and persons aged >_65 years or have more than five times the risk of developing SVT than younger individuals. Patients with lone paroxysmal SVT vs. those with cardiovascular disease are younger, have a faster SVT rate, have an earlier onset of symptoms, and are more likely to have their condition first documented in the emergency department.9 In a paediatric cohort study of 1 967 911 live births between 200008, 2021 patients (51.6% male, overall incidence 1.03/1000) had SVT [Wolff-Parkinson-White (WPW) syndrome accounted for 16.2%]. By the age of 15 years, the annual risk of sudden death was 0.01% per patient-year.10 In specialized centres, AVNRT is the most frequently treated substrate after AF, followed by atrial flutter and AVRT, in patients referred for catheter ablation.1113 Women are more likely to be affected by AVNRT than men (ratio 70:30),1416 while the converse is true for AVRT (ratio 45:55).14 A relationship with the monthly cycle has been suggested,17 and episodes are more frequent during pregnancy in women with pre-existing SVT.18 In the general population, the prevalence of a WPW pattern on surface electrocardiogram (ECG) ranges from 0.150.25%,19 increasing to 0.55% among first-degree relatives of affected patients.20 However, not all patients develop SVT and intermittent pre-excitation is not rare. Compared with the remaining population, the pre-excitation population is generally younger, predominantly male, and has less comorbidity.21,22 The proportion of patients with AVRT decreases with age, whereas the proportion of those with AVNRT and AT increases with age.14 The epidemiology of atrial flutter is not known with certainty, as atrial flutter and AF can coexist. The prevalence of AF before flutter ablation ranges from 2462%, and after ablation could be 3070%. The overall incidence of atrial flutter is 88/100 000 person-years in the US population annually. Adjusted for age, the incidence of atrial flutter in men (125/100 000) is >2.5 times that of women (59/ 100 000) and increases exponentially with age. Patients with atrial flutter are more likely to have been smokers, have a longer PR interval, history of myocardial infarction (MI), and history of heart failure (HF).23 Catheter ablation is now used extensively for most varieties of SVT, and patient-reported outcome measures have shown that patients experience significant improvements in their quality of life following ablation.2427 Patient-reported outcome measures using various questionnaires are useful in the audit of ablation techniques. Women are more often prescribed antiarrhythmic drugs before ablation for SVT than men,28 and recurrence rates following AVNRT ablation are higher in young women.29 However, overall, no significant differences in health-related quality of life or access to healthcare resources between men and women have been reported.28

7 Clinical presentation

The impact of SVT on an individual is based on a range of factors and may result in palpitations, fatigue, light-headedness, chest discomfort, dyspnoea, and altered consciousness.30 Rapid rhythms are more likely to present with a clear history and acutely than less-rapid rhythms, but SVT usually produces symptoms.31 The duration of symptoms and the patient’s age at onset are important. An individual with an onset in the teenage years or younger is less likely to have AT or AF continuing into adulthood. Such a long history will point towards a re-entrant mechanism.32 Dyspnoea, or other clinical signs and symptoms of HF, can occur when the patient has developed TCM. Light-headedness in association with SVT is not infrequent.30 Presyncope and syncope are less common,33,34 and tend to be associated with presentation in older individuals.32 In older patients, symptoms may be more extreme—with dizziness, presyncope, and syncope—in view of the less-accommodating characteristics of the circulation; drops in blood pressure are usually immediate and tend to recover.35 In some patients, a description of polyuria (possibly due to atrial stretch-induced atrial natriuretic peptide activity) can be elucidated, although this is infrequent.36 Direct risks due to SVT are unusual, but in specific situations (e.g. in patients with WPW syndrome and AF,22 or after atrial switch operation37) may lead to sudden cardiac death. A sudden onset more likely points to AVNRT or AVRT, although an AT may also present in this way.32 Characteristics in terms of the regularity or irregularity are helpful. The duration of individual episodes may help in terms of differentiation. Re-entrant tachycardias

Table 7 Initial evaluation of the patient with supraventricular tachycardia Standard • History, physical examination, and 12 lead ECG • Full blood counts, biochemistry profile, and thyroid function • An ECG during tachycardia should be sought • Transthoracic echocardiography Optional • Exercise tolerance testing • 24 h ECG monitoring, transtelephonic monitoring, or an implantable loop recorder • Myocardial ischaemia testing in patients with risk factors for coronary artery disease (including men aged >40 years and post-menopausal women) • An EPS should be considered for a definitive diagnosis and when cathe-

ter ablation is anticipated

ECG = electrocardiogram; EPS = electrophysiology study. Downloaded from academic.oup.com/eurheartj/article/41/5/655/5556821 by guest on 07 October 2026