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Qian PC, Barry MA, Tran VT, Lu J, McEwan A, Thiagalingam A, Thomas SP. Irrigated Microwave Catheter Ablation Can Create Deep Ventricular Lesions Through Epicardial Fat With Relative Sparing of Adjacent Coronary Arteries. Circ Arrhythm Electrophysiol 2020; 13:e008251. [PMID: 32299229 DOI: 10.1161/circep.119.008251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Radiofrequency ablation depth can be inadequate to reach intramural or epicardial substrate, and energy delivery in the pericardium is limited by penetration through epicardial fat and coronary anatomy. We hypothesized that open irrigated microwave catheter ablation can create deep myocardial lesions endocardially and epicardially though fat while acutely sparing nearby the coronary arteries. METHODS In-house designed and constructed irrigated microwave catheters were tested in in vitro phantom models and in 15 sheep. Endocardial ablations were performed at 140 to 180 W for 4 minutes; epicardial ablations via subxiphoid access were performed at 90 to 100 W for 4 minutes at sites near coronary arteries. RESULTS Epicardial ablations at 90 to 100 W produced mean lesion depth of 10±4 mm, width 18±10 mm, and length 29±8 mm through median epicardial fat thickness of 1.2 mm. Endocardial ablations at 180 W reached depths of 10.7±3.3 mm, width of 16.6±5 mm, and length of 20±5 mm. Acute coronary occlusion or spasm was not observed at a median separation distance of 2.7 mm (IQR, 1.2-3.4 mm). Saline electrodes recorded unipolar and bipolar electrograms; microwave ablation caused reductions in voltage and changes in electrogram morphology with loss of pace-capture. In vitro models demonstrated the heat sink effect of coronary flow, as well as preferential microwave coupling to myocardium and blood as opposed to lung and epicardial fat phantoms. CONCLUSIONS Irrigated microwave catheter ablation may be an effective ablation modality for deep ventricular lesion creation with capacity for fat penetration and sparing of nearby coronary arteries because of cooling endoluminal flow. Clinical translation could improve the treatment of ventricular tachycardia arising from mid myocardial or epicardial substrates.
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Affiliation(s)
- Pierre C Qian
- Cardiology Department, Westmead Hospital (P.C.Q., M.A.B., V.T.T., J.L., A.T., S.P.T.), University of Sydney, Australia.,Sydney Medical School (P.C.Q., A.T., S.P.T.), University of Sydney, Australia.,The Westmead Institute for Medical Research (P.C.Q., A.T., S.P.T.), University of Sydney, Australia
| | - Michael A Barry
- Cardiology Department, Westmead Hospital (P.C.Q., M.A.B., V.T.T., J.L., A.T., S.P.T.), University of Sydney, Australia.,School of Electrical and Information Engineering (M.A.B., A.M.), University of Sydney, Australia
| | - Vu T Tran
- Cardiology Department, Westmead Hospital (P.C.Q., M.A.B., V.T.T., J.L., A.T., S.P.T.), University of Sydney, Australia
| | - Juntang Lu
- Cardiology Department, Westmead Hospital (P.C.Q., M.A.B., V.T.T., J.L., A.T., S.P.T.), University of Sydney, Australia
| | - Alistair McEwan
- Cardiology Department, Westmead Hospital (P.C.Q., M.A.B., V.T.T., J.L., A.T., S.P.T.), University of Sydney, Australia.,School of Electrical and Information Engineering (M.A.B., A.M.), University of Sydney, Australia
| | - Aravinda Thiagalingam
- Sydney Medical School (P.C.Q., A.T., S.P.T.), University of Sydney, Australia.,The Westmead Institute for Medical Research (P.C.Q., A.T., S.P.T.), University of Sydney, Australia
| | - Stuart P Thomas
- Cardiology Department, Westmead Hospital (P.C.Q., M.A.B., V.T.T., J.L., A.T., S.P.T.), University of Sydney, Australia.,Sydney Medical School (P.C.Q., A.T., S.P.T.), University of Sydney, Australia.,The Westmead Institute for Medical Research (P.C.Q., A.T., S.P.T.), University of Sydney, Australia
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QIAN PIERRE, BARRY MICHAELANTHONY, NGUYEN TRANG, ROSS DAVID, KOVOOR PRAMESH, MCEWAN ALISTAIR, THOMAS STUART, THIAGALINGAM ARAVINDA. A Novel Microwave Catheter Can Perform Noncontact Circumferential Endocardial Ablation in a Model of Pulmonary Vein Isolation. J Cardiovasc Electrophysiol 2015; 26:799-804. [DOI: 10.1111/jce.12683] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2014] [Revised: 03/10/2015] [Accepted: 04/02/2015] [Indexed: 11/28/2022]
Affiliation(s)
- PIERRE QIAN
- Cardiology Department; Westmead Hospital; Sydney Australia
| | | | - TRANG NGUYEN
- Cardiology Department; Westmead Hospital; Sydney Australia
- School of Electrical and Information Engineering; University of Sydney; Sydney Australia
| | - DAVID ROSS
- Cardiology Department; Westmead Hospital; Sydney Australia
- Sydney Medical School; University of Sydney; Sydney Australia
| | - PRAMESH KOVOOR
- Cardiology Department; Westmead Hospital; Sydney Australia
- Sydney Medical School; University of Sydney; Sydney Australia
| | - ALISTAIR MCEWAN
- Cardiology Department; Westmead Hospital; Sydney Australia
- School of Electrical and Information Engineering; University of Sydney; Sydney Australia
| | - STUART THOMAS
- Cardiology Department; Westmead Hospital; Sydney Australia
- Sydney Medical School; University of Sydney; Sydney Australia
| | - ARAVINDA THIAGALINGAM
- Cardiology Department; Westmead Hospital; Sydney Australia
- Sydney Medical School; University of Sydney; Sydney Australia
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Chan JYS, Fung JWH, Yu CM, Feld GK. Preliminary Results with Percutaneous Transcatheter Microwave Ablation of Typical Atrial Flutter. J Cardiovasc Electrophysiol 2007; 18:286-9. [PMID: 17284286 DOI: 10.1111/j.1540-8167.2006.00742.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Linear microwave ablation has been shown to be effective for treatment of atrial fibrillation during open-heart surgery by producing transmural lesions in the atrium to isolate the pulmonary veins. However, the safety and efficacy of percutaneous, transcatheter, linear microwave ablation for atrial arrhythmias, while demonstrated in animal models, is unknown in humans. Therefore, we studied the safety and efficacy of linear microwave ablation of the cavotricuspid isthmus (CTI) in humans with typical atrial flutter, utilizing a 2-cm long microwave antenna mounted on a steerable 9-French catheter. METHODS AND RESULTS In seven consecutive patients, multielectrode catheters were positioned at the His bundle (quadripolar) and around the TV annulus (duo-decapolar) for pacing and recording atrial activation sequence before and after ablation. The microwave antenna was withdrawn gradually from tricuspid annulus towards inferior vena cava to ablate the CTI. Intracardiac ultrasound was used to ensure adequate endocardial contact of the microwave ablation catheter with the CTI. Microwave energy was applied at a power of 18 to 21 W at each ablation point for 120 seconds. Ablation was repeated until bidirectional CTI block was confirmed by demonstrating a descending activation wavefront in the contralateral atrial wall during pacing from the coronary sinus ostium or low lateral right atrium, respectively. Bidirectional isthmus block was achieved in all patients, after a mean number of 27.4 +/- 14.7 energy applications per patients. There were no acute procedural complications. CONCLUSIONS Percutaneous, transcatheter microwave ablation of CTI dependent atrial flutter was demonstrated to be safe and effective in this preliminary feasibility study.
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Affiliation(s)
- Joseph Yat-Sun Chan
- Department of Medicine and Therapeutics, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong SAR, China.
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Abstract
The safety and efficacy of catheter ablation for treatment of most types of cardiac arrhythmias are well established. These arrhythmias and arrhythmia substrates include AVNRT, accessory pathways, focal atrial tachycardia, atrial flutter, idiopathic ventricular tachycardia, and bundle-branch re-entry. Catheter ablation is considered as an alternative to pharmacologic therapy in the treatment of these cardiac arrhythmias.
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Affiliation(s)
- H Calkins
- Department of Medicine, Johns Hopkins Hospital, Baltimore, Maryland, USA.
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VanderBrink BA, Gilbride C, Aronovitz MJ, Lenihan T, Schorn G, Taylor K, Regan JF, Carr K, Schoen FJ, Link MS, Homoud MK, Estes NA, Wang PJ. Safety and efficacy of a steerable temperature monitoring microwave catheter system for ventricular myocardial ablation. J Cardiovasc Electrophysiol 2000; 11:305-10. [PMID: 10749353 DOI: 10.1111/j.1540-8167.2000.tb01799.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
INTRODUCTION Radiofrequency current delivered during cardiac ablation is limited by a rise in impedance secondary to coagulum formation on the ablation electrode. Microwave antennas continue to deliver energy despite the presence of coagulum; thus, temperature control of the ablation electrode may be even more important for microwave than for radiofrequency ablations to avoid thromboembolic risks. The purpose of this study was to test the safety and efficacy of an ablation system utilizing a feedback control system to maintain a fixed target temperature for creating lesions with multiple applications of microwave energy. METHODS AND RESULTS Microwave ablation was assessed using an 8.5-French catheter at 2 to 4 sites in 11 dogs. Microwave energy delivery was performed for 60 seconds three times at the same site. Power was regulated using a feedback control mechanism to maintain a target temperature of 75 degrees C. Ambulatory ECG monitoring was performed before and after ablation to assess arrhythmia occurrence. After follow-up, the dogs were euthanized, and lesion dimensions measured after fixation. The mean power applied to achieve the target temperature of 75 degrees C was 9.3+/-44 W. The mean depth of the lesions was 8.8+/-4.2 mm. The mean volume of the lesions was 304+/-240 mm3. Forty-four percent of the lesions were transmural. No endocardial thrombus was found. Ventricular tachycardia was observed acutely but resolved after 1 week. CONCLUSION Temperature feedback control systems for microwave ablation using a temperature-controlled system is feasible for myocardial ablation and creates uniform and large lesions; however, such large lesions can be acutely proarrhythmic.
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Affiliation(s)
- B A VanderBrink
- New England Medical Center, Boston, Massachusetts 02111, USA
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Vanderbrink BA, Gu Z, Rodriguez V, Link MS, Homoud MK, Estes NA, Rappaport CM, Wang PJ. Microwave ablation using a spiral antenna design in a porcine thigh muscle preparation: in vivo assessment of temperature profile and lesion geometry. J Cardiovasc Electrophysiol 2000; 11:193-8. [PMID: 10709714 DOI: 10.1111/j.1540-8167.2000.tb00319.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
INTRODUCTION Theoretical studies have suggested that microwave energy can increase the depth of heating compared with radiofrequency energy. A spiral microwave antenna design may have advantages over previous designs using smaller designs because the resulting power deposition pattern is considerably larger than the catheter diameter. We tested the efficacy of a spiral antenna using microwave energy in a porcine thigh muscle preparation. METHODS AND RESULTS In five anesthetized pigs, the thigh muscle was exposed and bathed in heparinized bovine blood (36 degrees to 37 degrees C). A helical microwave catheter with a fiberoptic thermometer attached to the distal end was positioned perpendicular to the thigh muscle. The antenna-tissue interface and tissue temperatures at depths of 3.0 and 6.0 mm were measured. A 915-MHz microwave generator delivered energy at one of three power outputs (50, 100, or 150 W) for 60 seconds. Seventy lesions were created: 50 W (n = 23), 100 W (n = 24), and 150 W (n = 23). The mean depths at 50, 100, and 150 W were 4.3 +/- 1.8 mm, 7.2 +/- 1.7 mm, and 9.4 +/- 0.9 mm, respectively. Lesion depth (R = 0.96, P = 0.05), maximum surface dimension (R = 0.99, P = 0.06), and volume (R = 0.99, P = 0.04) were closely correlated to the power applied. CONCLUSION Power is an important determinant of lesion size using a spiral microwave antenna. A novel, spiral microwave antenna design can create lesions of significant depth that may be applicable for the ablative therapy of ventricular tachycardia.
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Affiliation(s)
- B A Vanderbrink
- Cardiac Arrhythmia Center, New England Medical Center, Boston, Massachusetts 02111, USA
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Abstract
Because of the limitations of conventional radiofrequency ablation in creating large or linear lesions, alternative energy sources have been used as possible methods of catheter ablation. Modified radiofrequency energy, cryoablation, and microwave, laser, and ultrasound technologies may be able to create longer, deeper, and more controlled lesions and may be particularly suited for the treatment of ventricular tachycardias and for linear atrial ablation. Future studies will establish the efficacy of these new and promising technologies.
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Affiliation(s)
- P J Wang
- New England Medical Center, Cardiac Arrhythmia Service, Box 173, 750 Washington Street, Boston, MA 02111, USA
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Thomas SP, Clout R, Deery C, Mohan AS, Ross DL. Microwave ablation of myocardial tissue: the effect of element design, tissue coupling, blood flow, power, and duration of exposure on lesion size. J Cardiovasc Electrophysiol 1999; 10:72-8. [PMID: 9930912 DOI: 10.1111/j.1540-8167.1999.tb00644.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
INTRODUCTION The biophysical properties of microwave electromagnetic radiation suggest that it may be an alternative to radiofrequency (RF) energy for ablation of arrhythmias resistant to treatment using RF ablation. METHODS AND RESULTS The aim of this study was to characterize lesions produced using simple element designs in a blood superfused ovine tissue model to simulate endocardial ablation. The effect of tissue bath flow, duration of microwave exposure, and changes in forward power on lesion size were examined using a modified monopole element. Lesion size increased with increasing duration of exposure and increasing forward power (P < 0.05). Lesion depth was 0.7+/-0.7 mm after 30 seconds and 11.5+/-1.9 mm after 360 seconds. Lesion depths at 61, 71, and 80 W were 6.4+/-3.7, 8.9+/-2.0, and 11.9+/-1.2 mm, respectively. Altering flow within the bath from 3 to 5 L/min did not significantly change lesion size. CONCLUSION Simple element designs can be used to produce a range of lesions from very small sizes to lesions that are transmural in the ventricle. The temperature half-time for microwave ablation is far greater than that of RF ablation. Like RF lesions, the lesions produced by microwave ablation have greater width than depth. Deep penetration of lesions into the ventricular myocardium can only be achieved with these elements by producing lesions of perhaps unnecessarily large volume.
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Affiliation(s)
- S P Thomas
- Department of Cardiology, Westmead Hospital, New South Wales, Australia
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