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Percutaneous microwave
ablation of a lung tumor abutting
the heart
George A. Carberry, MD
Meghan G. Lubner, MD
Fred T. Lee Jr., MD
University of Wisconsin Hospital and Clinics
Madison, WI
Clinical history: 82 year-old woman
Past
Present
• 2003: Follicular thyroid
carcinoma
• Rising serum thyroglobulin
with enlarging RML
pulmonary nodule, a
presumed metastasis
• Meds: bisoprololhydrochlorothiazide 5-6.25
mg bid, levothyroxine 125
mcg qd
• Allergies: ASA, codeine,
quinine
• CBC and coags: WNL
– total thyroidectomy
– radioactive iodine
ablation
• 2013: Left upper lobe
pulmonary metastasis s/p
VATS resection
• PMH: HTN, paroxysmal
SVT, anti-RhE antibodies
with history of bleeding
following surgical
procedures
CT findings
A
B
Unenhanced axial (A) and coronal reconstructed (B) images from
chest CT demonstrate a lobular nodule abutting the right atrium
(arrows), increased in size from a chest CT performed 3 months prior.
How would you approach this
nodule for percutaneous ablation?
A
B
Unenhanced axial (A) and coronal reconstructed (B) images from
chest CT demonstrate a lobular nodule measuring 1.1 x 1.2 cm
abutting the right atrium (arrows), increased in size from a chest CT
performed 3 months prior.
How would you approach this
nodule for percutaneous ablation?
•
•
•
•
A. Anterior
B. Lateral
C. Posterior
D. Would not attempt
given nodule location
and patient’s history of
arrhythmia
How would you approach this
nodule for percutaneous ablation?
• A. Anterior
• Would center emission
point of antenna within
nodule
• Would expose greatest
volume of tumor to
microwave field (ellipsis)
• Would minimize normal
lung traversed
How would you approach this
nodule for percutaneous ablation?
• B. Lateral
• Would avoid crossing
fissure
• Would have difficulty
including cardiac margin
of the tumor in the
microwave field
• Would not center
emission point in tumor
How would you approach this
nodule for percutaneous ablation?
• C. Posterior
• Would traverse greatest
amount of normal lung
tissue
• Would traverse hilum
• Would cross fissure
How would you approach this
nodule for percutaneous ablation?
• D. Would not attempt
• Oligometastatic disease in setting of
long disease free interval associated
with improved outcomes following
local therapy1,2
• Limited treatment options for this
patient:
• Higher risk for surgery given comorbidities
• SBRT of central lung tumors associated
with complications from collateral tissue
injury3,4
• While patient’s pre-existing
arrhythmia important to consider,
thermoprotection from cardiac heat
sink and current use of thorascopic
MW antennas to safely treat cardiac
arrhythmias reassuring5
Planned approach
• Anterior intercostal approach
• Based on nodule size, use of a
single probe (PR probe,
NeuWave Inc., WI) would
cover tumor and a 5 mm
margin of lung tissue
Patient preparation
A
B
Cardiac monitor leads for continuous cardiac monitoring (A) and a
defibrillator pad (B) were applied to the patient’s chest. The patient was
at a theoretical higher risk for ablation-induced arrhythmia given her
history of underlying paroxysmal supraventricular tachycardia.
Probe placement
B
A
C
Axial (A), coronal (B) and sagittal (C) reconstructions following antenna
placement into the nodule confirm positioning of the antenna’s
emission point in the center of the tumor. Antenna placement was
performed with CT fluoroscopy (2.5 mm collimation; 0.5 s rotation time;
60 mA)
Probe placement
• Systole
A
• Diastole
B
A short run of continuous CT fluoroscopy was acquired to measure the
distance from outer right atrium to inner contour of antenna during
diastole (when heart closest to probe). Note the slightly closer distance
between heart and antenna at diastole.
Probe placement
• Systole
Goal distance was >5 mm based on estimated
probe-specific ablation zone geometry and the
• Diastole
assumption that cardiac heat sink and motion
would protect the adjacent heart tissue
6 mm
A
B
A short run of continuous CT fluoroscopy was acquired to measure the
distance from outer right atrium to inner contour of antenna during
diastole (when heart closest to probe). Note the slightly closer distance
between heart and antenna at diastole.
Ablation protocol
• MW power was slowly increased:
Start:
End:
45 W x 30 sec
50 W x 30 sec
55 W x 3 min
60 W x 30 sec
65 W x 1 min 30 sec
6 minutes of
ablation time
Intraprocedural monitoring
• Attention to the cardiac monitor by the
anesthesia team and interventionalists
– Development of premature beats (PVC or PACs)
would have prompted a decrease in power or
pulsing of power (e.g. 30 sec on and 30 sec off) to
limit growth of MW field
– Development of a ventricular arrhythmia (VT or VF)
or supraventricular arrhythmia would require
stopping the ablation with repositioning of the probe
ECG monitoring
No change from patient’s baseline cardiac rhythm
during the ablation
Ablation Confirmation
A commercial software program
integrated into the NeuWave
Intelligent Ablation System
(Ablation Confirmation™)
provided multiplanar color
overlays (Figure) that
demonstrate complete
coverage of the tumor (red
overlay) by the ablation zone
(green overlay)
Post procedure
• Tiny asymptomatic pneumothorax
– Stable over several CXRs
•
•
•
•
No intra-parenchymal hemorrhage
No pericardial effusion
No postprocedure pain
Patient discharged following day
Follow-up
• Post-ablation chest CT and repeat serum thyroglobulin to be
performed in 1 month
• Patient continues to have no signs or symptoms referable to
the lung ablation
Discussion
• Little data exist on safety of percutaneous thermal ablation near the
heart
• Heart represents a large heat sink, both protecting it from thermal
injury but also making it difficult to maintain lethal temperatures in
the tumor6,7
• MW able to achieve higher temperatures than RF and unaffected by
high electrical resistance in aerated lung, potentially making it a
useful modality for these cases8,9
• Irreversible electroporation not limited by heat sink but requires
multiple applicators, general anesthesia and cardiac
synchronization10
• More data is needed to determine a safe distance, power level
and duration at which a lung ablation can routinely be
performed near the heart.
References
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Lo, Simon S., et al. "The role of local therapy in the management of lung and liver
oligometastases." Nature Reviews Clinical Oncology 8.7 (2011): 405-416.
Rowe, Steven P., et al. "Advances in the Treatment of Oligometastatic Disease:: What the
Radiologist Needs to Know to Guide Patient Management." Academic radiology (2016).
Corradetti MN, Haas AR, Rengan R. Central-airway necrosis after stereotactic body-radiation
therapy. N Engl J Med 2012; 366: 2327-2329
Timmerman R., et al. Excessive toxicity when treating central tumors in a phase II study of
stereotactic body radiation therapy for medially inoperable early-stage lung cancer. J Clin Oncol
2006; 24:4833-4839
Lee, Sang Kwon, et al. "Epicardial microwave application in chronic atrial fibrillation surgery."
Journal of Korean medical science 20.5 (2005): 727-731.
Iguchi T, Hiraki T, Gobara H, Mimura H, Fujiwara H, Tajiri N, et al. Percutaneous radiofrequency
ablation of lung tumors close to the heart or aorta: evaluation of safety and effectiveness. JVIR.
2007;18(6):733-40.
Steinke, Karin, et al. "Safety of radiofrequency ablation of myocardium and lung adjacent to the
heart: an animal study." Journal of Surgical Research 114.2 (2003):140-145.
Brace CL, Hinshaw JL, Laeseke PF, et al. Pulmonary thermal ablation: comparison of
radiofrequency and microwave devices by using gross pathologic and CT findings in a swine
model. Radiology 2009; 251(3):705-711.
Wolf FJ, Grand DJ, Machan JT, et al. Microwave ablation of lung malignancies: effectiveness,
CT findings and safety in 50 patients. Radiology 2008; 247(3):871-879.
Deodhar, Ajita, et al. "Irreversible electroporation near the heart: ventricular arrhythmias can be
prevented with ECG synchronization." AJR. 196.3 (2011): W330.
Discussion questions
• What other concerns might you have with an
ablation near the heart and mediastinum?
• Has anyone treated a lung tumor near the
heart? Positive of negative outcome?
• Would anyone consider some form of tissue
displacement method for these tumors? E.g.
Iatrogenic pneumothorax, pleural effusion,
etc.