Papillary Muscle Ventricular Tachycardia
Idiopathic ventricular arrhythmias that originate from papillary muscles are not rare and account for 4–12% of idiopathic ventricular arrhythmias (Latchamsetty et al., JACC Clin Electrophysiol 1:116–23, 2015; Yamada et al., J Cardiovasc Electrophysiol 20:
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34
Hiroshi Tada
Keywords
Papillary muscle • Ventricular tachycardia • Premature ventricular contraction • Ventricular fibrillation
34.1 Introductory Remarks Idiopathic ventricular arrhythmias that originate from papillary muscles are not rare and account for 4–12% of idiopathic ventricular arrhythmias [1, 2]. Syncope and cardiac arrest due to papillary muscle arrhythmias are rare and generally non-life threatening. However, several cases of premature ventricular contractions (PVCs) from papillary muscles triggering ventricular fibrillation (VF) have been reported [3, 4]. The mechanism of the ventricular tachycardia (VT) is typically focal in nature and not reentrant. Catheter ablation may be required for symptomatic patients, patients with tachycardia-induced cardiomyopathy, or those with PVCs triggering ventricular fibrillation. Radiofrequency catheter ablation is challenging because of catheter instability during papillary muscle contractions and the thickened base of the papillary muscles, which might account for the variable success rate of this arrhythmia. The use of irrigation catheters with contact force sensing, intracardiac echocardiography, and image integration using 3-dimensional mapping systems can help to obtain acute success (elimination of targeted PVC/VTs). However, at present, the long-term prognosis after the ablation is unknown.
H. Tada, M.D., Ph.D. Faculty of Medical Sciences, Department of Cardiovascular Medicine, University of Fukui, 23-3 Matsuokashimoaizuki, Eiheiji-cho, Yoshida-gun, Fukui 910-1193, Japan e-mail: [email protected]
34.2 E pidemiology and Anatomic Considerations Recently, it has become known that idiopathic tachycardias (VTs) or premature ventricular contractions (PVCs) can originate from papillary muscles. Papillary muscle arrhythmias account for 4–12% of idiopathic arrhythmias [1, 2] and are generally non-life threatening. However, papillary muscle PVCs can trigger ventricular fibrillation (VF) [3, 4]. Patients with papillary muscle VT/PVCs seem to be older than those with VT/PVCs arising from the right ventricular (RV) OT and left ventricular (LV) fascicles [5, 6]. Papillary muscles support the subvalvular structures of the mitral and tricuspid valves. In the left ventricle (LV), the tension apparatus of both mitral leaflets inserts into two groups of papillary muscles. The anterior papillary muscle and posterior papillary muscle arise from a middle to apical site of the anterior or inferior wall of the LV, serving as an anatomic landmark for the beginning of the apical component of the LV. Their thickness (generally equal to the left ventricular [LV] wall [7]), prompt and dynamic movements, and contractions and relaxations with the cardiac cycles could cause difficulty for the catheter ablation of papillary muscle arrhythmias. Furthermore, variable exit sites from an intramural focus or its attachment to false cords may account for multiple QRS morphologies of papillary muscle arrhythmias [8]. Papillary muscle arrhythmias originate more commonly from the posteri
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