我々は博士に感謝します。レイモンウィンズロー、エリオット·マクベイ、 および ex vivo のデータセットonline.Thisリサーチを提供するためのジョンズ·ホプキンス大学のパトリック·ヘルムは、保健助成金の国立研究所R01-HL082729、国立科学財団助成CBET-0933029によってサポートされていました。

1。繊維配向推定<ol><li> 1ミリメートル3の解像度で、拡張期に正常な成人の人間の心の構造的MRIやDTMRI画像を取得する。フィッティングによりアトラス構造画像から心室心筋を抽出し、ImageJを使用して、各短軸スライスに対して、スライスで心外膜と心内膜の境界（ 図2Aおよび図2B）に沿って配置されたランドマーク点のセットを介してスプラインを閉じた。画像内のすべての10 番目のスライスのために手動でランドマーク点の配置を行う。直線DTMRI画像（ 図2C）のDTSの主固有ベクトルを計算することによって、アトラス心臓の繊維方向をMATLAB.Reconstruct使用して、手動で特定された点を補間することにより、残りのスライスのための画期的なポイントを取得します。 </li><li> 生体心臓CTやMRI で使用して拡張期にある患者の心臓の形状の画像を取得する。偵察アトラスが構築された方法（ 図3Aおよび図3B）と同様に画像から患者の心臓のジオメトリを構造体。患者画像面内分解能が1mm 2であることを前にこのような復興に再サンプリングする必要があります。同様に、ランドマークが手動でピックアップされているため、スライスの数、および面外挿の間隔はセグメント化された患者の心臓の画像が1mmのスライス厚を持つように調整する必要があります。 </li><li>二段階で患者ジオメトリイメージに合わせてアトラス心室画像を変形。最初のステップでは、13の観光スポット付近の点の集合に基づいてアフィン変換を実行：左心室（LV）尖、基部に2右心室（RV）の挿入ポイントを、ベースと頂点の間に2つのRVの挿入ポイントの途中、と2均等基地でRVおよびLV心外膜輪郭を分割ポイント、ベースと頂点の間の中間の4つのセット（ 図4A＆ <strong&gt;図4B）。第二段階では、変形はアフィン変換アトラスは、大変形微分同相写像メトリック（LDDMM）（ 図4C）を使用して 、患者ジオメトリに適合するように、さらに心室。 </li><li>モーフアフィンマッチングとLDDMM変換の変形場の変換行列に応じて画像のボクセルと再配向DTSの再ポジショニングによってアトラスのDTMRIイメージ。主方向の保全（PPD）メソッドを使用してDTSの再配向を実行します。 </li><li> DTS（ 図5）の主固有ベクトルを計算することによって、モーフィングアトラスDTMRIイメージから患者繊維配向の推定値を得る。 </li></ol> 2。推定誤差の測定<ol><li> 312.5×312.5×800μmの3の解像度で、通常の6と3障害のある犬の心の ex vivoでの構造的なMRとDTMR画像を取得する。ここでは、心臓FAIルアーは210分-1でtachypacing 3週間続いバンドル分岐左のラジオ波焼灼経由の犬歯で生成されるべきである。 </li><li>セグメント同様にイヌの心から人間アトラスの心臓に心室を、§1.1で説明されるように。 〜9心7（ 図6）のように、犬の心を失敗してから1〜6心として正常なイヌの心から分割し、それらのセグメント化された心室を示す。 </li><li>アトラス（ 図7）のような心の2から6までのそれぞれを用いて、心臓1の心室繊維配向の異なる5つの推定値を得る。 </li><li>アトラス（ 図8）のような心1を使用して失敗した心室のそれぞれについて、繊維の向きを推定する。 </li><li> θC-θA | |、ここで、θcとθの傾斜角が推定される推定繊維配向の各セット内のforeachデータポイントは、のように推定誤差を計算dは、それぞれ、その時点で繊維配向を取得しました。 </li><li>推定された繊維配向の各セット内の各データポイントは、thevector内積によって3次元（3D）でbetweenestimatedと繊維方向を取得した鋭角を計算します。 </li></ol> 3。シミュレーション上の推定誤差の影響の測定<ol><li>心臓1から、心臓1（モデル1と呼ぶ）、および5推定繊維配向データセット（モデル2から6）と5のDTMRI獲得した繊維配向を持つものを6モデルを構築する。3心不全のそれぞれについて、ジオメトリは、DTMRI獲得した繊維配向と推定繊維配向を持つもう1つずつ、合計2つの心室のモデルを構築する。ここでは、メッシュの平均エッジ長さの点で計算モデルの空間分解能は、600程度である必要があります。モデル9から7としてDTMRI獲得した繊維で心不全モデルを示し、estimat持つものモデル10〜12.Inモデルとしてedの繊維は、支配方程式と、心臓組織を記述するためにモノドメイン表記を使用します。 </li></ol><img src="/files/ftp_upload/50125/50125eq1.jpg" alt="式（1）" fo:content-width="2.18in" fo:src="/files/ftp_upload/50125/50125eq1highres.jpg" /> V mは膜電位であり、C m は膜特定の容量であり、 ここで、b は Potse ら 30で説明したようにbidomain伝導率テンソルから計算されるバルク伝導率テンソルσと私はイオンと、現在の膜貫通の密度であり、今度は、V mとmembrane.For C mを越えてイオンフラックスのダイナミクスを記述する状態変数μのセットに依存している、1μF / cm 2の値を使用します。正常イヌ心臓モデルでiを σについては、longitudiを使用0.34 S / mで、それぞれ0.06 S / mの外部および横伝導度の値。イヌ心室筋細胞のグリーンスタイン·ウィンズロウイオンモデルでL 経度を表しています。 30％（ 図9）でイヌ心不全心室モデルでの電気伝導度を下げます。 <ol start="2"><li>ソフトウェアパッケージCARP（CardioSolv、LLC）は、すべてのモデルでシミュレーションを洞調律を使用。 S1-S2ペーシング·プロトコルを使用して6失敗モデルでリエントラント心室頻拍（VT）を誘導する。 S2は納品後2秒間持続性VTの活性を得るために、S1とS2の間のタイミングを選択してください。 VTが任意のS1-S2のタイミングのために誘導されない場合は、VTが誘発されるまで、（ 図10）70％まで伝導率を減少させる。 </li><li>各シミュレーションのために、心を周囲の等方性浴で2点間の細胞外電位の差をとることにより、擬似心電図を計算します。分離した心臓の基地の近くに2ポイントを配置図10に示すように、それらを結ぶ線は、中隔のベース頂面に対して垂直になるようには18センチ。推定された繊維配向を持つ各シミュレーションでは、MADとしてメトリックを計算する</li></ol><img src="/files/ftp_upload/50125/50125eq2.jpg" alt="式（2）" fo:content-width="2.77in" fo:src="/files/ftp_upload/50125/50125eq2highres.jpg" /> Xは推定繊維配向を用いたシミュレーションのECG波形であり、Yは、取得した繊維配向のシミュレーションをthecorrespondingのECG波形であり、XはXの平均値であり、Yは、Yの平均値であり、Nはxの長さですとY。

<ol>
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A., Yu, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Remodeling+of+cardiac+fiber+structure+after+infarction+in+rats+quantified+with+diffusion+tensor+MRI.">Remodeling of cardiac fiber structure after infarction in rats quantified with diffusion tensor MRI.</a> American Journal of Physiology - Heart and Circulatory Physiology. 285 (3), H946-H954 (2003).</li><li>Stecker, E. C., Chugh, S. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prediction+of+sudden+cardiac+death:+next+steps+in+pursuit+of+effective+methodology.">Prediction of sudden cardiac death: next steps in pursuit of effective methodology.</a> Journal of Interventional Cardiac Electrophysiolog. 31 (2), 101-107 (2011).</li></ol>

特別な利害関係は宣言されません。

本研究ではDTMRIの非存在下では、正常および失敗心室の心筋の繊維配向が心臓電気生理学のシミュレーションで使用するためにそれらのジオメトリの体内画像から推定することができる、ことを定量的に示しています。提案された方法論は 、in vivo CTデータ内に示したが、それが直接患者繊維配向を獲得する能力の欠如に対処する、心室ジオメトリーの in vivoでのMR <...

<html>計算論的アプローチは、健康と疾患における心臓の機能の理解の進歩の中心になりつつあります。電気生理学および電気機械技術の最先端の全心臓モデルは現在、通常の心室伝播、不整脈、除細動、電気機械結合、および心臓再同期1などの現象の広い範囲を勉強するために使用されている。しかし、臨床環境で直接適用可能であることが計算論的アプローチのために、それはモデルが患者に特化したものが、モデルが特定のアーキテクチャと、患者の疾患のある心臓の電気生理学的または電気機械的特性に基づいている必要がありますつまりことが不可欠です。そのようなモデルを用いたシミュレーションは、それによって劇的に心臓医療2-4改善、電気生理学的な介入だけでなく、予防のために高度にパーソナライズされた決定に到達するために医師を支援するでしょう。 内容は、 &quot;現実的な心臓モデルの&gt;作成は繊維配向は、心臓に電気伝播とひずみ分布の方向を決定し、患者の心臓の形状と繊維構造の取得を必要とし、したがって、それらを取得することは心臓のモデリング5,6に不可欠です。で医用イメージングの最近の進歩は、それが今では磁気共鳴イメージング（MRI）やコンピューター断層撮影（CT）技術を用いて高分解能で生体内での患者の心、そのような梗塞などincludingstructural改造、の幾何学的形状を得ることが可能ではありません。ただし、特定の設置生体内での患者の心臓の繊維構造体を取得するための実用的な方法。拡散テンソル（DT）のMRI検査7,8、そのまま心臓の繊維の向きを取得する唯一の手法では、9特定の制限のため、生体内で広く利用可能ではありません。簡単な説明臨床の現場にDTMRIを翻訳する前の努力がelsewhを見つけることができるのERE 2。このような繊維配向のルールベースの割り当てなどの方法論がDTMRIに代わるものを提供していますが、これらの方法論は、特定の重大な制限2、10を持っています。したがって、in vivoで心臓繊維構造を取得することが困難で、現在臨床現場での電気生理学的および電気機械心臓シミュレーションの適用を妨げる。本研究の目的は、直接、このニーズに対応することでした。 私たちは、心臓の心室繊維配向が正確に心臓やアトラスは、ジオメトリと繊維配向可能です心臓部であるアトラスのジオメトリに対して予測することができるという仮説を立てた。したがって、我々は、in vivoで心臓繊維の向きを推定するための方法論を開発するために従来技術の状態を使用し、ノーマルと失敗イヌ心室2に仮説を検証した。当社繊維見積もり手法の中心的な考え方は、similaritieを利用することである唯一のジオメトリ情報が提供されている（ターゲット）の心のおおよその繊維構造するために、さまざまな心の間でジオメトリを基準に、繊維配向、のs。私達の見積もり手法の中心には、大変形微分同相メトリックマッピング（LDDMM）11と、主成分（PPD）の2、12の保存を使用して、アトラスの繊維配向のモーフィングを使用して、ターゲットジオメトリを持つアトラスジオメトリの登録です。diffeomorphicpropertyはそれによってintegrityof解剖学的構造を維持するアトラスは、変形中に&quot;foldover&quot;自体をしないことを保証LDDMM、の図1は、我々の方法の処理パイプラインを示しています。プロトコルテキストセクション§1推定例の患者のために行うことができますどのように実証することにより、パイプラインのさまざまなコンポーネントについて説明します。 図1のブロックのいくつかの中の数字は、対応するを参照してください。セクションの下のサブセクション§プロトコルテキストの1。 我々は、計算的に地域の電気活性化マップと同様に擬似心電図（擬似心電図）をシミュレートすることにより、推定誤差を定量化し、心臓電気生理学のこのエラーonsimulationsの効果を測定することにより、提案手法の性能を評価した。人間の心の使用不能に起因する、性能評価は、13から15までの先行研究から利用可能なイヌの心臓を用いて行った。推定誤差は傾斜角度16、角度測定がepicardialsurfaceに平行にカットされperformedon組織切片の組織学アールのfollowingthe伝統によって算出した。 anglebetween繊維方向および心外膜接平面がgenerallysmall 17、18であるので、その傾斜角を使用して完全にfiberdirectionを記述する上で情報の損失は軽微であります。 comput用モデルで以前に19,20、および心臓組織が ​​確立数学的手法と実験データ21から25に基づいて表現されて報告されているようにationalシミュレーション、画像ベースのモデルが構築されました。洞調律は、S1-S2ペーシングプロトコル27でプルキンエネットワーク26、および心室頻拍、由来の複製活性化によるシミュレーションを行った。擬似心電図は28を計算し、平均絶対偏差（MAD）メトリック29を用いて比較した。

<table border="1"><tbody><tr><td> LDDMM </td><td>ジョンズ·ホプキンス大学</td><td></td><td> <a href="http://cis.jhu.edu/software/lddmm-volume/index.php" target="_blank">http://cis.jhu.edu/software/lddmm-volume/index.php</a> </td></tr><tr><td> MATLAB </td><td> The MathWorks、Inc。社</td><td> R2011b </td><td> <a href="http://www.mathworks.com/products/matlab/" target="_blank">http://www.mathworks.com/products/matlab/</a> </td></tr><tr><td> ImageJの</td><td>国立衛生研究所</td><td></td><td> <a href="http://rsbweb.nih.gov/ij/" target="_blank">http://rsbweb.nih.gov/ij/</a> </td></tr><tr><td>タランチュラ</td><td> CAEソフトウェアソリューション</td><td></td><td> <a href="http://www.meshing.at/Spiderhome/Tarantula.html" target="_blank">http://www.meshing.at/Spiderhome/Tarantula.html</a> </td></tr><tr><td> CARP </td><td> CardioSolv</td><td></td><td> <a href="http://cardiosolv.com/" target="_blank">http://cardiosolv.com/</a> </td></tr><tr><td>犬の画像</td><td>ジョンズ·ホプキンス大学</td><td></td><td> <a href="http://www.ccbm.jhu.edu/research/DTMRIDS.php" target="_blank">http://www.ccbm.jhu.edu/research/DTMRIDS.php</a> </td></tr></tbody></table>

patient-specific modeling of the heart: estimation of ventricular fiber orientations

心臓治療をパーソナライズすることを目的と心臓（DYS）関数の患者固有のシミュレーションは、臨床的に心筋の繊維の向きを取得するためのin vivoイメージング技術の存在しないことによって妨げられている。このプロジェクトの目的は、患者の心臓形状の体内画像から心臓の繊維の向きを推定するための方法論を開発することでした。心室ジオメトリーと繊維配向の正確な表現は、アトラスと呼ばれ、高解像度のex vivoでの構造的磁気共鳴（MR）と、通常の人間の心の拡散テンソル（DT）のMR画像から、それぞれ再建された。患者の心臓の心室ジオメトリは生体コンピュータ断層撮影（CT）画像でから、半自動セグメンテーションを経由して 、抽出した。画像変換アルゴリズムを使用して、アトラス心室ジオメトリーは、患者のそれと一致するように変形した。最後に、変形場はアトラス繊維orientatに適用されたイオン患者繊維配向の推定値を求める。繊維上の見積りの精度は通常の6と3障害のある犬の心を用いて評価した。獲得したと推定繊維配向の傾斜角度との間の平均の差の絶対値は15.4°であった。プロジェクトから得られた臨床的に観察level.The新しい洞察と見積もられ、取得された繊維配向の間に有意な差がないことが示された洞調律および心室頻拍中の心室興奮マップと擬似心電図の計算シミュレーションは、開発のための道を開く電気生理学的介入についてのパーソナライズされた診断の医師と意思決定を支援することができ、心臓の患者固有のモデル。

図11は 、ACはノーマルと失敗の心の中だけでなく、推定DTMRI由来の繊維配向の合理化された視覚化を表示します。定性検査は、推定された繊維配向がDTMRI由来のものとよく合っていることを示しています。パネルDは心臓1の幾何学的に重ね、示し、正常な心 &#39;の傾斜角度の誤差の分布は、すべての5つの推計値を平均。パネルEは心臓1の幾何学的に重ね、心 &#39;の傾斜角度を失敗?...

Watch this Scientific Journal Video about Patient-specific Modeling of the Heart: Estimation of Ventricular Fiber Orientations at JoVE.com

Patient-specific Modeling of the Heart: Estimation of Ventricular Fiber Orientations

パーソナライズされたモデリングのための患者の心臓形状の体内画像から心室繊維配向を推定するための方法論が説明されています。通常の使用およびイヌの心を失敗実行方法論の検証は、臨床的に観察可能なレベルで推定し、取得した繊維配向の間に有意な差がないことがあることを示している。

ハートの患者固有のモデリング：心室繊維配向の推定

Patient-specific  simulations of heart (dys)function aimed at personalizing cardiac therapy are hampered  by the absence of in vivo imaging technology for ...

patient-specific-modeling-heart-estimation-ventricular-fiber

Research

JoVE Journal

Bioengineering

13.6K ビュー.  Johns Hopkins University. パーソナライズされたモデリングのための患者の心臓形状の体内画像から心室繊維配向を推定するための方法論が説明されています。通常の使用およびイヌの心を失敗実行方法論の検証は、臨床的に観察可能なレベルで推定し、取得した繊維配向の間に有意な差がないことがあることを示している。

ビデオ: Patient-specific Modeling of the Heart: Estimation of Ventricular Fiber Orientations

High-resolution Fiber-optic Microendoscopy for in situ Cellular Imaging

Many biological and clinical studies require the longitudinal study and analysis of morphology and function with cellular level resolution. Traditionally, multiple experiments are run in parallel, with individual samples removed from the study at sequential time points for evaluation by light microscopy. Several intravital techniques have been developed, with confocal, multiphoton, and second harmonic microscopy all demonstrating their ability to be used for imaging in situ 1. With these systems, however, the required infrastructure is complex and expensive, involving scanning laser systems and complex light sources. Here we present a protocol for the design and assembly of a high-resolution microendoscope which can be built in a day using off-the-shelf components for under US$5,000. The platform offers flexibility in terms of image resolution, field-of-view, and operating wavelength, and we describe how these parameters can be easily modified to meet the specific needs of the end user.
We and others have explored the use of the high-resolution microendoscope (HRME) in in vitro cell culture 2-5, in excised 6 and living animal tissues 2,5, and in human tissues in vivo 2,7. Users have reported the use of several different fluorescent contrast agents, including proflavine 2-4, benzoporphyrin-derivative monoacid ring A (BPD-MA) 5, and fluoroscein 6,7, all of which have received full, or investigational approval from the FDA for use in human subjects. High-resolution microendoscopy, in the form described here, may appeal to a wide range of researchers working in the basic and clinical sciences. The technique offers an effective and economical approach which complements traditional benchtop microscopy, by enabling the user to perform high-resolution, longitudinal imaging in situ.

High-resolution Fiber-optic Microendoscopy for in situ Cellular Imaging

In many biological and clinical situations it is advantageous to study cellular processes as they evolve in their native microenvironment. Here we describe the assembly and use of a low-cost fiber-optic microscope which can provide real time imaging in cell culture, animal studies, and clinical patient studies.

高分解能光ファイバMicroendoscopy用その場で細胞イメージング

Many biological and clinical studies require the longitudinal study and analysis of morphology and function with cellular level resolution.  ...

生物工学

Multiparametric Optical Mapping of the Langendorff-perfused Rabbit Heart

Optical imaging and fluorescent probes have significantly advanced research methodology in the field of cardiac electrophysiology in ways that could not have been accomplished by other approaches1. With the use of the calcium- and voltage-sensitive dyes, optical mapping allows measurement of transmembrane action potentials and calcium transients with high spatial resolution without the physical contact with the tissue. This makes measurements of the cardiac electrical activity possible under many conditions where the use of electrodes is inconvenient or impossible1. For example, optical recordings provide accurate morphological changes of membrane potential during and immediately after stimulation and defibrillation, while conventional electrode techniques suffer from stimulus-induced artifacts during and after stimuli due to electrode polarization1. 
The Langendorff-perfused rabbit heart is one of the most studied models of human heart physiology and pathophysiology. Many types of arrhythmias observed clinically could be recapitulated in the rabbit heart model. It was shown that wave patterns in the rabbit heart during ventricular arrhythmias, determined by effective size of the heart and the wavelength of reentry, are very similar to that in the human heart2. It was also shown that critical aspects of excitation-contraction (EC) coupling in rabbit myocardium, such as the relative contribution of sarcoplasmic reticulum (SR), is very similar to human EC coupling3. Here we present the basic procedures of optical mapping experiments in Langendorff-perfused rabbit hearts, including the Langendorff perfusion system setup, the optical mapping systems setup, the isolation and cannulation of the heart, perfusion and dye-staining of the heart, excitation-contraction uncoupling, and collection of optical signals. These methods could be also applied to the heart from species other than rabbit with adjustments to flow rates, optics, solutions, etc.
Two optical mapping systems are described. The panoramic mapping system is used to map the entire epicardium of the rabbit heart4-7. This system provides a global view of the evolution of reentrant circuits during arrhythmogenesis and defibrillation, and has been used to study the mechanisms of arrhythmias and antiarrhythmia therapy8,9. The dual mapping system is used to map the action potential (AP) and calcium transient (CaT) simultaneously from the same field of view10-13. This approach has enhanced our understanding of the important role of calcium in the electrical alternans and the induction of arrhythmia14-16.

This article describes the basic procedures for conducting optical mapping experiments in the Langendorff-perfused rabbit heart using the panoramic imaging system, and the dual (voltage and calcium) imaging modality.

ランゲンドルフ灌流ウサギの心臓のMultiparametric光学マッピング

Optical imaging and fluorescent probes have significantly advanced research methodology in the field of cardiac electrophysiology in ways that could not ...

Targeting Neuronal Fiber Tracts for Deep Brain Stimulation Therapy Using Interactive, Patient-Specific Models

Deep brain stimulation (DBS), which involves insertion of an electrode to deliver stimulation to a localized brain region, is an established therapy for movement disorders and is being applied to a growing number of disorders. Computational modeling has been successfully used to predict the clinical effects of DBS; however, there is a need for novel modeling techniques to keep pace with the growing complexity of DBS devices. These models also need to generate predictions quickly and accurately. The goal of this project is to develop an image processing pipeline to incorporate structural magnetic resonance imaging (MRI) and diffusion weighted imaging (DWI) into an interactive, patient specific model to simulate the effects of DBS. A virtual DBS lead can be placed inside of the patient model, along with active contacts and stimulation settings, where changes in lead position or orientation generate a new finite element mesh and solution of the bioelectric field problem in near real-time, a timespan of approximately 10 seconds. This system also enables the simulation of multiple leads in close proximity to allow for current steering by varying anodes and cathodes on different leads. The techniques presented in this paper reduce the burden of generating and using computational models while providing meaningful feedback about the effects of electrode position, electrode design, and stimulation configurations to researchers or clinicians who may not be modeling experts.

The goal of this project is to develop an interactive, patient-specific modeling pipeline to simulate the effects of deep brain stimulation in near real-time and provide meaningful feedback as to how these devices influence neural activity in the brain.

対話型、患者固有のモデルを用いた脳深部刺激療法の神経繊維の管を対象と

Deep brain stimulation (DBS), which involves insertion of an electrode to deliver stimulation to a localized brain region, is an established therapy for ...

Light-sheet Fluorescence Microscopy for the Study of the Murine Heart

Light-sheet fluorescence microscopy has been widely used for rapid image acquisition with a high axial resolution from micrometer to millimeter scale. Traditional light-sheet techniques involve the use of a single illumination beam directed orthogonally at sample tissue. Images of large samples that are produced using a single illumination beam contain stripes or artifacts and suffer from a reduced resolution due to the scattering and absorption of light by the tissue. This study uses a dual-sided illumination beam and a simplified CLARITY optical clearing technique for the murine heart. These techniques allow for deeper imaging by removing lipids from the heart and produce a large field of imaging, greater than 10 x 10 x 10 mm3. As a result, this strategy enables us to quantify the ventricular dimensions, track the cardiac lineage, and localize the spatial distribution of cardiac-specific proteins and ion-channels from the post-natal to adult mouse hearts with sufficient contrast and resolution.

This study uses a dual-sided illumination light-sheet fluorescence microscopy (LSFM) technique combined with optical clearing to study the murine heart.

マウス心臓の研究のための光シート蛍光顕微鏡

Light-sheet fluorescence microscopy has been widely used for rapid image acquisition with a high axial resolution from micrometer to millimeter scale. ...

Biaxial Mechanical Characterizations of Atrioventricular Heart Valves

Extensive biaxial mechanical testing of the atrioventricular heart valve leaflets can be utilized to derive&#160;optimal parameters used in constitutive models, which provide a mathematical representation of the mechanical function of those structures. This presented biaxial mechanical testing protocol involves (i) tissue acquisition, (ii) the preparation of tissue specimens, (iii) biaxial mechanical testing, and (iv) postprocessing of the acquired data. First, tissue acquisition requires obtaining porcine or ovine hearts from a local Food and Drug Administration-approved abattoir for later dissection to retrieve the valve leaflets. Second, tissue preparation requires using tissue specimen cutters on the leaflet tissue to extract a clear zone for testing. Third, biaxial mechanical testing of the leaflet specimen requires the use of a commercial biaxial mechanical tester, which consists of force-controlled, displacement-controlled, and stress-relaxation testing protocols to characterize the leaflet tissue&#39;s mechanical properties. Finally, post-processing requires the use of data image correlation techniques and force and displacement readings to summarize the tissue&#39;s mechanical behaviors in response to external loading. In general, results from biaxial testing demonstrate that the leaflet tissues yield a nonlinear, anisotropic mechanical response. The presented biaxial testing procedure is advantageous to other methods since the method presented here allows for a more comprehensive characterization of the valve leaflet tissue under one unified testing scheme, as opposed to separate testing protocols on different tissue specimens. The proposed testing method has its limitations in that shear stress is potentially present in the tissue sample. However, any potential shear is presumed negligible.

This protocol involves characterizations of atrioventricular valve leaflets with force-controlled, displacement-controlled, and stress-relaxation biaxial mechanical testing procedures. Results acquired with this protocol can be used for constitutive model development to simulate the mechanical behavior of functioning valves under a finite element simulation framework.

房室弁の二軸の機械特性

Extensive biaxial mechanical testing of the atrioventricular heart valve leaflets can be utilized to derive&#160;optimal parameters used in constitutive ...

Optical Imaging of Isolated Murine Ventricular Myocytes

The ability to isolate adult cardiac myocytes has permitted researchers to study a variety of cardiac pathologies at the single cell level. While advances in calcium sensitive dyes have permitted the robust optical recording of single cell calcium dynamics, recording of robust transmembrane optical voltage signals has remained difficult. Arguably, this is because of the low single to noise ratio, phototoxicity, and photobleaching of traditional potentiometric dyes. Therefore, single cell voltage measurements have long been confined to the patch clamp technique which while the gold standard, is technically demanding and low throughput. However, with the development of novel potentiometric dyes, large, fast optical responses to changes in voltage can be obtained with little to no phototoxicity and photobleaching. This protocol describes in detail how to isolate adult murine myocytes which can be used for cellular shortening, calcium, and optical voltage measurements. Specifically, the protocol describes how to use a ratiometric calcium dye, a single-excitation calcium dye, and a single excitation voltage dye. This approach can be used to assess the cardiotoxicity and arrhythmogenicity of various chemical agents. While phototoxicity is still an issue at the single cell level, methodology is discussed on how to reduce it.

We present the methodology for the isolation of murine myocytes and how to obtain voltage or calcium traces simultaneously with sarcomere shortening traces using fluorescence photometry with simultaneous digital cell geometry measurements.

単離マウス心室筋細胞の光学イメージング

The ability to isolate adult cardiac myocytes has permitted researchers to study a variety of cardiac pathologies at the single cell level. While advances ...

Evaluation of Left Ventricular Structure and Function using 3D Echocardiography

Three-dimensional (3D) quantification of the left ventricle (LV) provides significant added value in terms of diagnostic accuracy and precise risk stratification in various cardiac disorders. Recently, 3D echocardiography became available in routine cardiology practice; however, high-quality image acquisition and subsequent analysis have a steep learning curve. The present article aims to guide the reader through a detailed 3D protocol by presenting tips and tricks and also by highlighting the potential pitfalls to facilitate the widespread but technically sound use of this important technique concerning the LV. First and foremost, we show the acquisition of a high-quality 3D dataset with optimal spatial and temporal resolution. Then, we present the analytical steps toward a detailed quantification of the LV by using one of the most widely applied built-in software. We will quantify LV volumes, sphericity, mass and also systolic function by measuring ejection fraction and myocardial deformation (longitudinal and circumferential strain). We will discuss and provide clinical examples about the essential scenarios where the transition from a conventional echocardiographic approach to a 3D-based quantification is highly recommended.

In this article, we provide a step-by-step acquisition and analysis protocol for the volumetric assessment and speckle-tracking analysis of the left ventricle by 3D echocardiography, particularly focusing on practical aspects that maximize the feasibility of this technique.

3D心エコーを用いた左心室構造と機能の評価

Three-dimensional (3D) quantification of the left ventricle (LV) provides significant added value in terms of diagnostic accuracy and precise risk ...

Patient-Specific Polyvinyl Alcohol Phantom Fabrication with Ultrasound and X-Ray Contrast for Brain Tumor Surgery Planning

Phantoms are essential tools for clinical training, surgical planning and the development of novel medical devices. However, it is challenging to create anatomically accurate head phantoms with realistic brain imaging properties because standard fabrication methods are not optimized to replicate any patient-specific anatomical detail and 3D printing materials are not optimized for imaging properties. In order to test and validate a novel navigation system for use during brain tumor surgery, an anatomically accurate phantom with realistic imaging and mechanical properties was required. Therefore, a phantom was developed using real patient data as input and 3D printing of molds to fabricate a patient-specific head phantom comprising the skull, brain and tumor with both ultrasound and X-ray contrast. The phantom also had mechanical properties that allowed the phantom tissue to be manipulated in a similar manner to how human brain tissue is handled during surgery. The phantom was successfully tested during a surgical simulation in a virtual operating room.
The phantom fabrication method uses commercially available materials and is easy to reproduce. The 3D printing files can be readily shared, and the technique can be adapted to encompass many different types of tumor.

This protocol describes the fabrication of a patient specific skull, brain and tumor phantom. It uses 3D printing to create molds, and polyvinyl alcohol (PVA-c) is used as the tissue mimicking material.

超音波による患者特異的ポリビニルアルコールファントム作製法とX線コントラストによる脳腫瘍手術計画

Phantoms are essential tools for clinical training, surgical planning and the development of novel medical devices. However, it is challenging to create ...

Evaluating Regional Pulmonary Deposition using Patient-Specific 3D Printed Lung Models

Development of targeted therapies for pulmonary diseases is limited by the availability of preclinical testing methods with the ability to predict regional aerosol delivery. Leveraging 3D printing to generate patient-specific lung models, we outline the design of a high-throughput, in vitro experimental setup for quantifying lobular pulmonary deposition. This system is made with a combination of commercially available and 3D printed components and allows the flow rate through each lobe of the lung to be independently controlled. Delivery of fluorescent aerosols to each lobe is measured using fluorescence microscopy. This protocol has the potential to promote the growth of personalized medicine for respiratory diseases through its ability to model a wide range of patient demographics and disease states. Both the geometry of the 3D printed lung model and the air flow profile setting can be easily modulated to reflect clinical data for patients with varying age, race, and gender. Clinically relevant drug delivery devices, such as the endotracheal tube shown here, can be incorporated into the testing setup to more accurately predict a device&#8217;s capacity to target therapeutic delivery to a diseased region of the lung. The versatility of this experimental setup allows it to be customized to reflect a multitude of inhalation conditions, enhancing the rigor of preclinical therapeutic testing.

We present a high-throughput, in vitro method for quantifying regional pulmonary deposition at the lobe level using CT scan-derived, 3D printed lung models with tunable air flow profiles.

患者固有の3Dプリント肺モデルを用いた局所肺堆積の評価

Development of targeted therapies for pulmonary diseases is limited by the availability of preclinical testing methods with the ability to predict ...

Quantification of Mouse Heart Left Ventricular Function, Myocardial Strain, and Hemodynamic Forces by Cardiovascular Magnetic Resonance Imaging

Mouse models have contributed significantly to understanding genetic and physiological factors involved in healthy cardiac function, how perturbations result in pathology, and how myocardial diseases may be treated. Cardiovascular magnetic resonance imaging (CMR) has become an indispensable tool for a comprehensive in vivo assessment of cardiac anatomy and function. This protocol shows detailed measurements of mouse heart left ventricular function, myocardial strain, and hemodynamic forces using 7-Tesla CMR. First, animal preparation and positioning in the scanner are demonstrated. Survey scans are performed for planning imaging slices in various short- and long-axis views. A series of prospective ECG-triggered short-axis (SA) movies (or CINE images) are acquired covering the heart from apex to base, capturing end-systolic and end-diastolic phases. Subsequently, single-slice, retrospectively gated CINE images are acquired in a midventricular SA view, and in 2-, 3-, and 4-chamber views, to be reconstructed into high-temporal resolution CINE images using custom-built and open-source software. CINE images are subsequently analyzed using dedicated CMR image analysis software.
Delineating endomyocardial and epicardial borders in SA end-systolic and end-diastolic CINE images allows for the calculation of end-systolic and end-diastolic volumes, ejection fraction, and cardiac output. The midventricular SA CINE images are delineated for all cardiac time frames to extract a detailed volume-time curve. Its time derivative allows for the calculation of the diastolic function as the ratio of the early filling and atrial contraction waves. Finally, left ventricular endocardial walls in the 2-, 3-, and 4-chamber views are delineated using feature-tracking, from which longitudinal myocardial strain parameters and left ventricular hemodynamic forces are calculated. In conclusion, this protocol provides detailed in vivo quantification of the mouse cardiac parameters, which can be used to study temporal alterations in cardiac function in various mouse models of heart disease.

This study describes a comprehensive cardiovascular magnetic resonance imaging (CMR) protocol to quantify the left ventricular functional parameters of the mouse heart. The protocol describes the acquisition, post-processing, and analysis of the CMR images as well as assessment of different cardiac functional parameters.

心臓血管磁気共鳴画像法によるマウス心左心室機能、心筋緊張、血行力の定量化

Mouse models have contributed significantly to understanding genetic and physiological factors involved in healthy cardiac function, how perturbations ...