Dose-Escalation Study for Cardiac Radiosurgery in a Porcine Model

Blanck, Oliver; Bode, Frank; Gebhard, Maximilian; Hunold, Peter; Brandt, Sebastián; Bruder, Ralf; Großherr, M.; Vonthein, Reinhard; Rades, Dirk; Dunst, Juergen

doi:10.1016/j.ijrobp.2014.02.036

Cited by 81 publications

(101 citation statements)

References 33 publications

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“…The dose of 25 Grays was adopted from the first human case report by Lo, et al [8]; this dose was considered safe, and safety was our highest priority. Dose escalation above 25 Gy (30 Gy or more) leads to scar formation so the treatment might be more effective, as reported by Blanck, et al [12]. All in all, the dose issue is one of the most interesting points in cardiac radiosurgery; we believe that our paper speeds up the discussion and moves this extremely promising area of functional radiosurgery a step forward.…”

Section: Discussionsupporting

confidence: 64%

Cardiac Radiosurgery for Malignant Ventricular Tachycardia

Cvek¹,

Neuwirth²,

Knybel³

et al. 2014

Cureus

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Section: Discussionsupporting

confidence: 64%

Cardiac Radiosurgery for Malignant Ventricular Tachycardia

Cvek¹,

Neuwirth²,

Knybel³

et al. 2014

Cureus

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“…4 Preclinical studies demonstrated electrophysiological conduction blockade and histological fibrosis after SABR to the cardiac conduction pathway, providing proof of principle for treating arrhythmias. 1 Unlike thermal ablation that causes immediate coagulative necrosis and subsequent scarring, ablative radiation leads to a complex cascade of acute and chronic tissue effects, including microvascular endothelial cell apoptosis, oxidative injury, inflammation, and fibrosis. This tissue injury mechanism may account for the observed time course of clinical response and subsequent recurrence in the subject.…”

Section: Discussionmentioning

confidence: 99%

Stereotactic Ablative Radiotherapy for the Treatment of Refractory Cardiac Ventricular Arrhythmia

Loo

Soltys

Wang

et al. 2015

Circ: Arrhythmia and Electrophysiology

161

173

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A 71-year-old man with coronary artery disease, coronary artery bypass grafting in 2000, baseline ejection fraction of 0.24, and implantation of a single chamber implanted cardioverter defibrillator (ICD) in 2009 for ventricular tachycardia (VT) presented with continuous episodes of nonsustained and sustained VT refractory to sotalol and mexiletine. Despite angioplasty and stent for coronary artery disease, VT continued for 2 years. Medical history included atrial fibrillation and oxygen-dependent chronic obstructive pulmonary disease. Baseline electrocardiogram (ECG) showed atrial fibrillation with a ventricular rate of 82 beats per minute with inferior Q waves and QRS duration of 90 ms. Twelve-lead ECG during VT showed a regular, wide-complex tachycardia at 160 beats per minute (CL 380-400 ms), with a right bundle branch block pattern, superior axis, precordial transition at V3-V4. His ICD log showed numerous VT episodes, with a single morphology seen on intracardiac ventricular electrogram, cycle length 380-411ms. Episodes were nonsustained, pace-terminated, and shock-terminated. As catheter ablation was relatively medically contraindicated, he consented to a Food and Drug Administration and Institutional Review Board-approved compassionate-use protocol of stereotactic arrhythmia radioablation (STAR), noninvasive ablation of VT substrate by stereotactic ablative radiotherapy (SABR) techniques for tumors. STAR therapy was delivered in October, 2012. STAR Planning and DeliveryBaseline echocardiogram showed a dilated left ventricle (LV), ejection fraction of 0.24, with basal inferior aneurysm, and apical and infero-posterior akinesis. Positron emission tomography-computed tomography showed extensive hypometabolic scar in the LV extending between the LV base and the apex, involving the inferior, inferoseptal, and inferolateral walls. A target for STAR was delineated using proprietary visualization and contouring software (CardioPlan™, CyberHeart™, Portola Valley, CA), outlining the target volume corresponding to what would have been the likely catheter ablation volume for this VT substrate based on imaging-defined inferior LV scar and 12-lead ECG QRS morphology during VT, implying a likely inferior LV VT circuit location ( Figure 1A). The target volume was transferred to the radiation treatment planning software (MultiPlan 4.6.0, Accuray, Sunnyvale, CA) of the treatment system (CyberKnife®, Accuray, Sunnyvale, CA), with normal organs delineated, including lungs, esophagus, and stomach.A temporary pacing wire (Oscor, Inc., Miami Lakes, FL) was fluoroscopically placed in the RV apex as an imaging fiducial marker that could be dynamically tracked to compensate for respiratory motion (Synchrony® Respiratory Tracking 9.6.0, Accuray, Sunnyvale, CA). The magnitude of the remaining cardiac motion was determined by fluoroscopy of the fiducial marker during transient breath holds, and the final target volume included an expansion to encompass this residual motion. The finalized target was then used for treatment planning.A...

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“…Initial lesion contouring was performed with the CardioPlan® Software (CyberHeart Inc, Sunnyvale, USA) and an isotropic margin of 3 mm was added to generate the Right and Left Planning Target Volumes (RPTV / LPTV) based on the accuracy of the CyberKnife [14], and previous studies [1-3, 5, 6, 9-11, 15]. An extra margin for the cardiac motion was not generated by the cardiac motion at the PV antrum is small [5-7, 18, 21, 23] and has a likely neglectable impact on the dosimetry [15, 36]. …”

Section: Methodsmentioning

confidence: 99%

“…As opposed to invasively implanting fiducials [6, 7, 9], this procedure is only minimally invasive and has been investigated in a single human treated for cardiac arrhythmia [10, 11], however not for AF. A potential location for an AF radiosurgery guiding catheter would be the atrial septum in the right atrium, mainly to avoid the crossing into the left atrium which may bear significant risks for the patient [12].…”

Section: Methodsmentioning

confidence: 99%

Treatment Planning Considerations for Robotic Guided Cardiac Radiosurgery for Atrial Fibrillation

Blanck¹,

Ipsen²,

Chan³

et al. 2016

Cureus

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PurposeRobotic guided stereotactic radiosurgery has recently been investigated for the treatment of atrial fibrillation (AF). Before moving into human treatments, multiple implications for treatment planning given a potential target tracking approach have to be considered. Materials & MethodsTheoretical AF radiosurgery treatment plans for twenty-four patients were generated for baseline comparison. Eighteen patients were investigated under ideal tracking conditions, twelve patients under regional dose rate (RDR = applied dose over a certain time window) optimized conditions (beam delivery sequence sorting according to regional beam targeting), four patients under ultrasound tracking conditions (beam block of the ultrasound probe) and four patients with temporary single fiducial tracking conditions (differential surrogate-to-target respiratory and cardiac motion). ResultsWith currently known guidelines on dose limitations of critical structures, treatment planning for AF radiosurgery with 25 Gy under ideal tracking conditions with a 3 mm safety margin may only be feasible in less than 40% of the patients due to the unfavorable esophagus and bronchial tree location relative to the left atrial antrum (target area). Beam delivery sequence sorting showed a large increase in RDR coverage (% of voxels having a larger dose rate for a given time window) of 10.8-92.4% (median, 38.0%) for a 40-50 min time window, which may be significant for non-malignant targets. For ultrasound tracking, blocking beams through the ultrasound probe was found to have no visible impact on plan quality given previous optimal ultrasound window estimation for the planning CT. For fiducial tracking in the right atrial septum, the differential motion may reduce target coverage by up to -24.9% which could be reduced to a median of -0.8% (maximum, -12.0%) by using 4D dose optimization. The cardiac motion was also found to have an impact on the dose distribution, at the anterior left atrial wall; however, the results need to be verified.ConclusionRobotic AF radiosurgery with 25 Gy may be feasible in a subgroup of patients under ideal tracking conditions. Ultrasound tracking was found to have the lowest impact on treatment planning and given its real-time imaging capability should be considered for AF robotic radiosurgery. Nevertheless, advanced treatment planning using RDR or 4D respiratory and cardiac dose optimization may be still advised despite using ideal tracking methods.

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Dose-Escalation Study for Cardiac Radiosurgery in a Porcine Model

Cited by 81 publications

References 33 publications

Cardiac Radiosurgery for Malignant Ventricular Tachycardia

Cardiac Radiosurgery for Malignant Ventricular Tachycardia

Stereotactic Ablative Radiotherapy for the Treatment of Refractory Cardiac Ventricular Arrhythmia

Treatment Planning Considerations for Robotic Guided Cardiac Radiosurgery for Atrial Fibrillation

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