Case of Successful Sympathetic Nerve Modulation by Targeted Heavy Ion Radiotherapy for Idiopathic Ventricular Tachycardia

Abstract

Non-invasive radioablation using stereotactic body radiation therapy with X-ray has been proposed as a rescue treatment for refractory ventricular tachycardia (VT). However, there are concerns about the occurrence of late valvular or coronary disease. We treated VT originating from the aortic sinus cusp using the Bragg peak principle of a heavy ion beam, minimizing the dose to the aortic valve and coronary artery and providing an anti-arrhythmic effect and cardiac function recovery due to improved sympathetic nerve heterogeneity. We present a method for targeting sympathetic nerve distribution using ¹²³I-metaiodobenzylguanidine scintigraphy.

Keywords: 123I‐metaiodobenzylguanidine scintigraphy; arrhythmia radioablation; non‐invasive irradiation technique; sympathetic denervation; targeted heavy ion radiotherapy; ventricular arrhythmia.

FIGURE 1

(A) Molecular weight, (B) Physical property, (C) Organs at risk. Bragg peak principle: When a high‐speed charged particle passes through a material, the incident‐heavy ion gradually loses energy and eventually stops. The energy loss peaks immediately before the heavy ion beam stops and quickly approaches zero. This maximum range is named the spread‐out of the Bragg peak after its discoverer. The ionization density of the X‐rays increases until it reaches its maximum value; thus, the energy remains constant after passing through the target material.

FIGURE 2

(A) Twelve‐lead electrocardiography (ECG), (B) Pseudo‐12‐lead ECG in ambulatory ECG. Sustained ventricular tachycardia (VT)‐1, VT‐2, and VT‐3 shows 176–190 bpm, left bundle branch block, inferior axis, and transition zone of V3.

FIGURE 3

DVH: The graph displays the dose (GyE) on the horizontal axis and the percentage of exposed intracardiac structures on the vertical axis. The upper right of the target area and the lower left of the normal organs may be a better treatment plan. Heavy ion's Bragg peak creates a steep dose gradient near the target. Cropped ‐CTV, ‐PTV is the volume created by considering organs at risk. AV, aortic valve; CTV, clinical target volume; LA, left atrium; LAD, left anterior descending artery; LCx, left circumflex artery; LMT, left main trunk; LV, left ventricle; PTV, planning target volume; RA, right ventricle; RV, right ventricle.

FIGURE 4

(A) Arrhythmia events, (B) Single PVC, (C) Twelve‐lead electrocardiography (ECG) after radiotherapy. ICD, implantable cardioverter‐defibrillator; NSVT, non‐sustained VT; PVC, premature ventricular contraction; RT, radiotherapy; VF, ventricular fibrillation; VT, ventricular tachycardia.

FIGURE 5

(A) Diastolic function, (B) LV volume, (C) Systolic function. E/A, early peak filling rate to atrial‐peak filling rate; EF, ejection fraction.

FIGURE 6

(A) ¹²³I‐MIBG polar map (delay), (B) ^99mTc‐TF polar map, (C) ^99mTc‐TF phase map. ¹²³I‐MIBG, 123I‐metaiodobenzylguanidine scintigraphy; ^99mTc‐TF, (99m)Technetium‐tetrofosmin.