High‐Intensity Focused Ultrasound Ablation of Myocardium In Vivo and Instantaneous Biological Response

Zheng, Minjuan; Shentu, Weihui; Chen, Dingzhang; Sahn, David J.; Zhou, Xiaodong

doi:10.1111/echo.12526

Cited by 7 publications

(11 citation statements)

References 21 publications

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“…The increasing trend in amplitude of movement of the posterior wall indicated the compensatory action that maintained the systolic function. This observation agreed with the results obtained from the regional TDI hypokinesis of the ablated region without significant variation in global cardiac function [ 15 ]. Decreasing diastolic function (both global parameters of E/A, E′/A′, and regional parameter of Ea/Aa) was found post-ablation compared with pre-ablation.…”

Section: Discussionsupporting

confidence: 91%

“…Each heart was dissected to approximately 1-mm-thick slices to expose and carefully ascertain the range of ablation lesions. Maximal lesion length (D 1 ), width (D 2 ), and depth (D 3 ) were measured, and the mean diameters (D 1 + D 2 + D 3 )/3 and mean volumes (0.5233 D 1 D 2 D 3 ) [ 15 ] were calculated. Then, the ablated cardiac specimens were fixed in 10 % phosphate-buffered formalin (pH 7) and sent for histopathological examinations.…”

Section: Methodsmentioning

confidence: 99%

“…The mechanism of RF septal ablation to reduce LVOT gradient is by hypokinesis or akinesis of the ablated region [ 14 ], rather than thinning the septum in surgical septal myectomy [ 4 ]. High-intensity focused ultrasound (HIFU) was reported to be efficacious in ablating the septum and the LV free wall in canine myocardium without influencing the cardiac function [ 15 ]. However, given the difficulty in controlling the HIFU energy, the transducer size and the pulmonary vein isolation hamper the application of this technique.…”

Section: Introductionmentioning

confidence: 99%

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Echocardiography-guided percutaneous per-ventricular laser ablation of ventricular septum: in vivo study in a canine model

Sun

Zhang

et al. 2016

Lasers Med Sci

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Surgical myectomy and ethanol ablation are established intervention strategies for left ventricular outflow obstruction in hypertrophic cardiomyopathy. Safety and efficacy limitations of these interventions call for a minimally invasive, potentially safer, and more efficacious strategy. In this study, we aimed to evaluate the feasibility of echocardiography-guided percutaneous per-ventricular laser ablation of a ventricular septum in a canine model. Six domestic dogs were chosen for the study. A 21G needle was inserted into the right ventricle with its tip reaching the targeted basal to mid-septum, after which laser ablation was performed as follows: 1-W laser for 3 min (180 J) at the basal segment and 5 min (300 J) at middle segment of the septum, respectively. Echocardiography, blood chemistry tests, and pathology examination were performed to assess the results of laser ablation. No death or major complications, i.e., tamponade, pericardial effusion, or ventricular fibrillation, occurred. The laser-ablated areas were well demarcated in the results of the pathological examination. The diameters of the ablated regions were 4.42 ± 0.57 and 5.28 ± 0.83 mm for 3 and 5 min ablation, respectively. Pre-ablation and post-ablation, cardiac enzymes were found to increase significantly while no significant differences were found among M-mode, 2D (LVEF), pulsed-wave (PW) Doppler, and tissue Doppler imaging (TDI) measurements. Contrast echocardiography confirmed the perfusion defects in the ablated regions. Microscopically, the ablated myocardium showed coagulative changes and a sparse distribution of disappearing nuclei and an increase in eosinophil number were observed. Our study suggests that percutaneous and per-ventricular laser ablation of the septum is feasible, potentially safe and efficacious, and warrants further investigation and validation.

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Section: Discussionsupporting

confidence: 91%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Echocardiography-guided percutaneous per-ventricular laser ablation of ventricular septum: in vivo study in a canine model

Sun

Zhang

et al. 2016

Lasers Med Sci

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“…Lesion size was smaller than in in vivo model, suggesting that temperature cooling through blood flow is important in HIFU, similar to RF ablation. 10 Okumura et al studied HIFU ablation of the right superior pulmonary vein (RSPV) in eight dogs using a steerable HIFU catheter (10 Fr balloon, diameter 24 mm; ProRhythm Inc.). Electrical PVI was confirmed in seven of eight PVs.…”

Section: Studies In Animal Modelsmentioning

confidence: 99%

“…The authors proposed that a distance of .7.5 mm between the HIFU exit and important structures is needed to prevent collateral damage. 10 As we will explore in the following section, collateral injury may occur despite best intentions with HIFU.…”

Section: Studies In Animal Modelsmentioning

confidence: 99%

The role of high-intensity focused ultrasound in ablation of atrial fibrillation and other cardiac arrhythmias

Danon¹,

Nair²,

Koruth³

et al. 2015

RRFU

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Atrial fibrillation is the most prevalent arrhythmia of the heart, originating usually from ectopic atrial activity of the pulmonary veins. Therefore, one of the treatment options is pulmonary vein isolation. Among the novel approaches to pulmonary vein isolation, highintensity focused ultrasound (HIFU) has been developed. The ultrasound energy can be focused on a specific area and would result in the formation of a lesion similar to that formed with radiofrequency (RF) ablation. Although preclinical studies were promising, clinical studies in patients resulted in lower efficacy and high complication rates in comparison to the standard ablation method, due to collateral damage. Using HIFU for epicardial approach during cardiac surgery and for extracorporeal ablation does seem to have a future role. In this review, we present the mechanism of HIFU lesion formation and the principal studies.

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Molecular and histological effects of MR-guided pulsed focused ultrasound to the rat heart

Jang

Nagle

et al. 2017

J Transl Med

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BackgroundImage-guided high intensity focused ultrasound has been used as an extracorporeal cardiac pacing tool and to enhance homing of stem cells to targeted tissues. However, molecular changes in the myocardium after sonication have not been widely investigated. Magnetic-resonance (MR)-guided pulsed focused ultrasound (pFUS) was targeted to the rat myocardium over a range of pressures and the microenvironmental and histological effects were evaluated over time.MethodsEight-to-ten-week-old Sprague–Dawley rats received T2-weighted MR images to target pFUS to the left ventricular and septum without cardiac or respiratory gating. Rats were sonicated through the thoracic wall at peak negative pressures (PNP) from 1 to 8 MPa at a center frequency of 1 MHz, 10 ms pulse duration and 1 Hz pulse repetition frequency for 100 pulses per focal target. Following pFUS, myocardium was harvested over 24 h and subjected to imaging, proteomic, and histological measurements.ResultspFUS to the myocardium increased expression of cytokines, chemokines, and trophic factors characterized by an initial increase in tumor necrosis factor (TNF)-α followed by increases in pro- and anti-inflammatory factors that returned to baseline by 24 h. Immediately after pFUS, there was a transient (< 1 h) increase in N-terminal pro b-type natriuretic peptide (NT-proBNP) without elevation of other cardiac injury markers. A relationship between PNP and expression of TNF-α and NT-proBNP was observed with significant changes (p < 0.05 ANOVA) ≥ 4 MPa compared to untreated controls. Contrast-enhanced ex vivo T1-weighted MRI revealed vascular leakage in sonicated myocardium that was accompanied by the presence of albumin upon immunohistochemistry. Histology revealed infiltration of neutrophils and macrophages without morphological myofibril changes in sonicated tissue accompanied by pulmonary hemorrhage at PNP > 4 MPa.ConclusionsMR-guided pFUS to myocardium induced transient proteomic and histological changes. The temporal proteomic changes in the myocardium indicate a short-lived sterile inflammatory response consistent with ischemia or contusion. Further study of myocardial function and strain is needed to determine if pFUS could be developed as an experimental model of cardiac injury and chest trauma.Electronic supplementary materialThe online version of this article (10.1186/s12967-017-1361-y) contains supplementary material, which is available to authorized users.

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High‐Intensity Focused Ultrasound Ablation of Myocardium In Vivo and Instantaneous Biological Response

Abstract: HIFU can be used for the controllable ablation of myocardial tissue, with instantly increased serum markers, decreased regional wall motion, and unaffected left ventricular global function.

Cited by 7 publications

References 21 publications

Echocardiography-guided percutaneous per-ventricular laser ablation of ventricular septum: in vivo study in a canine model

Echocardiography-guided percutaneous per-ventricular laser ablation of ventricular septum: in vivo study in a canine model

The role of high-intensity focused ultrasound in ablation of atrial fibrillation and other cardiac arrhythmias

Molecular and histological effects of MR-guided pulsed focused ultrasound to the rat heart

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