Biz Dr teşekkür ederim. Raimond Winslow, Elliot McVeigh ve ex vivo gerçekleştirmede online.This araştırma sağlayan Johns Hopkins Üniversitesi&#39;nde Patrick Helm Sağlık hibe Ulusal Sağlık Enstitüleri R01-HL082729 ve Ulusal Bilim Vakfı Hibe CBET-0933029 tarafından desteklenmiştir.

1. Fiber Yönelimler Tahmini <ol><li> 1 mm 3 çözünürlükte, diyastolde normal yetişkin insan kalbinin yapısal MRG ve DTMRI görüntüler elde edin. ImageJ kullanarak, her kısa eksen dilim için, uydurma tarafından atlas yapısal görüntü ventrikülün ayıklamak dilim epikardiyal ve endokardiyal sınırlar (Şekil 2A ve Şekil 2B) boyunca yerleştirilmiş dönüm noktaları bir dizi aracılığıyla spline kapatıldı. Görüntüdeki her 10 inci dilim için elle dönüm noktalarının yerleşimi gerçekleştirin. Doğrusal DTMRI resim (Şekil 2C) içkisizlikten birincil özvektörlerini bilgisayar tarafından atlası kalp lif yönelim MATLAB.Reconstruct kullanılarak el ile tespit noktaları interpolasyon yoluyla kalan dilimleri için dönüm noktaları elde edilir. </li><li> Vivo Kardiyak BT veya MRI kullanarak diyastolde hastanın kalp geometri bir görüntü elde edin. Reconbenzer atlas (Şekil 3A ve Şekil 3B) inşa edildi yolu görüntüden hasta kalp geometrisi struct. Hasta görüntü düzlem çözünürlüklü 1 mm 2 olduğunu önceki gibi yeniden yeniden örneklenmiş olmalıdır. Benzer şekilde, önemli noktalara elle toplanır hangi dilimleri ve out-of-düzleminde interpolasyon aralığı sayısını parçalı hasta kalp image 1 mm kesit kalınlığı vardır, böylece ayarlanması gerekir. </li><li> Deform atlas ventriküler görüntü iki adımda hasta geometri görüntü maç. İlk adımda, onüç simgesel noktaları bir dizi dayalı bir afin dönüşümü gerçekleştirmek: sol ventrikül (LV) apeks, üssünde iki sağ ventrikül (RV) ekleme noktaları, taban ve apeks arasındaki iki RV ekleme noktaları yarıda, ve iki eşit üssünde RV ve LV epikardiyal konturlar bölmek noktaları ve taban ve tepe arasındaki yarıda dört set (Şekil 4A &amp; <strong&gt; Şekil 4B). İkinci adımda ise, deforme afin-dönüştürülmüş atlası büyük bir deformasyon diffeomorphic metrik birim (LDDMM) (Şekil 4C) kullanılarak, hastaya geometrisi için daha ileri ventriküller. </li><li> Morph afin eşleme dönüşüm matrisi ve LDDMM dönüşümün deformasyon alanına göre görüntü vokseller ve yeniden yönlendirmek içkisizlikten yeniden konumlandırma atlas DTMRI görüntü. Asal doğrultular (PPD) yönteminin korunması kullanarak içkisizlikten yeniden yönelim gerçekleştirin. </li><li> (Şekil 5) içkisizlikten birincil eigenvector bilgisayar tarafından morphed atlası DTMRI görüntü hasta lif açısının tahminini elde edin. </li></ol> 2. Tahmin Hata Ölçülmesi <ol><li> Ex vivo yapısal MR ve altı normal ve üç başarısız köpek kalpleri DTMR görüntüleri Edinme, 312.5 bir çözünürlükte × 312.5 × 800 mikron 3. Burada, kalp faicazibesine dk -1 210 tachypacing 3 hafta takip dal sol radyofrekans ablasyonu ile kanin üretilmiş olmalıdır. </li><li> Benzer insan atlası kalp gibi § 1.1 &#39;de açıklandığı köpek kalbinden Segmenti ventriküller. 9 ile kalpleri 7 (Şekil 6) gibi köpek kalpleri başarısız 6 ile kalpleri 1 gibi normal köpek kalpleri bölümlenmiş ve bu segmente karıncıklar Etmektedir. </li><li> Bir atlas (Şekil 7) olarak 6 kupa 2&#39;nin her kullanılarak kalbin 1 ventrikül lif yönelimleri beş farklı tahminler edinin. </li><li> Atlas (Şekil 8) gibi kalp 1 kullanarak başarısız ventriküllerin her lif yönelimleri tahmin. </li><li> Θ c-θ a | |, burada θ c ve θ a eğim açıları tahmin edilmektedir tahmini lif yönelimlerin her set Foreach veri noktası olarak tahmin hatasını hesaplamakd sırasıyla, bu noktada elyaf yönelimleri satın aldı. </li><li> Tahmini lif açısının Her sette her veri noktası için thevector dot ürün ile üç boyutlu (3D) olarak betweenestimated ve lif yönleri edinilmiş akut açı hesaplamak. </li></ol> 3. Simülasyonlar üzerine Tahmin Hata Etkilerinin Ölçümü <ol><li> Kalp 1&#39;den, kalp 1 (örnek 1 olarak anılmaktadır), ve yaklaşık beş lif yönelim gerçekleştirmede (model 2-6) ile beş arasında DTMRI edinilmiş elyaf yönlenmiş bir altı modeller oluşturmuştur. Üç kalp yetmezliğinin her biri için, geometrileri, DTMRI edinilmiş lif oryantasyon ve tahmini elyaf yönelimleri ile diğer bir iki ventrikül modeller geliştirirler. İşte kafesleri ortalama kenar uzunluğu açısından hesaplanan modellerin uzaysal çözünürlüğü, 600 mikron hakkında olmalıdır. Modelleri 7&#39;den 9&#39;a kadar DTMRI kökenli lifler ile kalp yetmezliği modelleri gösterelim ve estimat olanlarmodelleri 10 12.In modelleri olarak ed lifler, denklemleri ile, kardiyak doku tanımlamak için monodomain gösterimi kullanın: </li></ol><img src="/files/ftp_upload/50125/50125eq1.jpg" alt="Denklem 1" fo:content-width="2.18in" fo:src="/files/ftp_upload/50125/50125eq1highres.jpg" /> V m transmembran potansiyeli olduğunu;, C m zar spesifik kapasitans ise, burada b Potse ve diğerleri tarafından tarif edildiği gibi 30 bidomain iletkenlik tensörleri hesaplanır hacim iletkenliği tansörü olup σ ve iyon, transmembran akım yoğunluğudur sırayla V m ve membrane.For C m çapında iyonik akılarının dinamiklerini açıklayan durum değişkenlerinin μ bir dizi bağlıdır, 1 μ F / cm 2 arasında bir değer kullanın. Normal kanin kalp modellerinden i σ için, uzunlamasına kullanın0.34 S / m ve 0.06 S / m, nal ve enine iletkenlik değerleri. Köpek ventriküler miyosit arasında Greenstein-Winslow iyonik modelleri l lon Temsil. % 30 (Şekil 9) tarafından kanin kalp yetmezliği ventriküler modelleri elektriksel iletkenlikleri azaltın. <ol start="2"><li> Yazılım paketi CARP (CardioSolv, LLC), tüm modeller ile simüle sinüs ritmi kullanma. S1-S2 uyarım protokolü kullanarak altı başarısız modellerde reentran ventriküler taşikardi (VT) neden olur. S1 ve S2 doğumdan sonra 2 sn boyunca devam VT aktivite elde etmek S2 arasındaki zamanlamayı seçin. VT herhangi S1-S2 zamanlama için indüklenen değilse VT (Şekil 10) indüklendi kadar% 70&#39;e varan tarafından iletkenlikleri azaltın. </li><li> Her simülasyon için, kalplerini çevreleyen izotropik banyosunda iki nokta arasındaki ekstraselüler potansiyellerinin fark alarak sözde EKG&#39;si hesaplayabilirsiniz. Ayrılmış kalp tabanına yakın iki nokta yerleştirinŞekil 10 de gösterildiği gibi, bu bağlantı hattı septumun baz-apeks düzleme dik olan bu tür 18 cm, tarafından. Tahmini elyaf yönelimleri ile her simülasyon için, MAD metrik olarak hesaplamak </li></ol><img src="/files/ftp_upload/50125/50125eq2.jpg" alt="Denklem 2" fo:content-width="2.77in" fo:src="/files/ftp_upload/50125/50125eq2highres.jpg" /> X tahmini elyaf yönelimleri simülasyon EKG dalga, Y kazanılmış elyaf yönelimleri ile simülasyon thecorresponding ve EKG dalga, X X ortalama değeri, Y, Y, ortalama değeri ve n X uzunluğu ve Y.

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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>

Çıkar çatışması ilan etti.

Bu araştırma DTMRI yokluğunda, normal ve başarısız ventriküllerin kalp kası lif yönelim kardiyak elektrofizyoloji simülasyonları içinde kullanım için geometriler in-vivo görüntüler ile tahmin edilebilir, ki nicel olarak göstermektedir. Önerilen metodoloji vivo BT veri ile gösterilmiştir, ancak bunu doğrudan hastanın lif oryantasyon edinme becerisi eksikliği adresleme, ventriküler geometrinin vivo MR görüntülerinde de uygulanabilir olduğunu. Bu ned...

<html> Hesaplamalı yaklaşım, sağlık ve hastalıkta kalbin fonksiyonunun anlayışının ilerlemesi merkezi haline geliyor. Elektrofizyoloji ve elektromekanik Devlet-of-the-art tam kalbinde modelleri şu anda böyle normal ventrikül yayılımı, aritmi, defibrilasyon, elektromekanik eşleşme ve kardiyak resenkronizasyon 1 gibi olaylar geniş bir yelpazede, incelemek için kullanılmaktadır. Ancak, klinik ortamda, doğrudan uygulanabilir nitelikte olduğu hesaplamalı yaklaşım için, bu model hastaya özgü, modeller özgü mimarisi ve hastalıklı kalbin elektrofizyolojik veya elektromekanik özelliklerine dayalı olmalıdır yani olması şarttır. Bu tür modeller ile Simülasyon böylece dramatik kalp sağlık 2-4 iyileştirilmesi, elektrofizyolojik müdahaleler yanı sıra profilaksisi için yüksek düzeyde kişiselleştirilmiş kararlara varmak için doktorlar yardımcı olacaktır. içeriği &quot;gerçekçi kardiyak modelleri&gt; Yaratılış Fiber yönelimleri kalbinde elektriksel yayılımı ve gerilme dağılımları yön belirlemek. hastanın kalp geometrisi ve lif yapısı kazanılmasını gerektirir ve bu nedenle almadan kardiyak modelleme 5, 6 esastır. Birlikte Medikal görüntülemede son gelişmeler, artık manyetik rezonans görüntüleme (MRG) ve bilgisayarlı tomografi (BT) teknolojileri kullanarak yüksek çözünürlüklü in vivo bir hasta kalp gibi enfarktüsü gibi includingstructural remodeling, geometri elde etmek mümkündür. Ancak, yoktur in vivo bir hastanın kalp lif yapısı elde etmek için pratik bir yöntem. Difüzyon tensör (DT) MRG 7, 8, sağlam kalp lif yönelimleri elde etmenin tek yöntemi, 9 belli sınırlamalar nedeniyle in vivo yaygın değildir. kısa bir açıklama klinik ortama DTMRI çevirmek için önceki çalışmalar elsewh bulunabilir veere 2. Elyaf yönelimlerin kural tabanlı atama gibi yöntemler DTMRI için alternatifler sunmak olsa da, bu yöntemler bazı ciddi sınırlamalar 2, 10 var. Böylece, in vivo kardiyak lif yapısı elde zorluklar halen klinik ortamda elektrofizyolojik ve elektromekanik kardiyak simülasyonları uygulamasını engellemektedir. Bu araştırmanın amacı, doğrudan bu ihtiyaca cevap vermek oldu. Biz bir kalp ventriküler lif yönelimleri doğru kalp ve atlas geometrisi ve lif yönelimler vardır bir kalp bir atlas, geometrisi verilen tahmin edilebilir olduğunu varsaydık. Buna göre, biz in vivo kardiyak lif açısının hesaplanması için bir metodoloji geliştirmek için sanat teknikleri devlet kullanılır ve normal ve köpek karıncıklar 2 başarısız hipotezi test. Bizim lif tahmini metodolojisinin ana fikri similaritie yararlanmak içinsırayla sadece geometriyi bilgi mevcut olduğu bir (hedef) kalbin yaklaşık olarak lif yapısına farklı kalpler arasında geometriye göre lif yönelim, s. Bizim tahmini metodolojisi kalbinde büyük deformasyon diffeomorphic metrik eşleme (LDDMM) 11, ve temel bileşenler (PPD) 2, 12 korunması kullanarak atlas lif yönelimlerin morphing kullanarak hedef geometrisi ile atlas geometrinin kaydı. Diffeomorphicproperty atlas deformasyon sırasında değil &quot;Foldover&quot; kendisi, böylece integrityof anatomik yapıları koruyarak yapar. Şekil 1 bizim metodoloji işlem boru göstermektedir ki LDDMM teminat. Protokol metin bölümü § 1 tahmin bir örnek hasta için yapılabilir nasıl ortaya koyarak bu boru hattının çeşitli bileşenleri açıklanmaktadır. Şekil 1 &#39;de bazı bloklar içinde karşılık gelen sayılar için bakınızbölümünde alt § protokol metnin 1. Biz hesaplama yerel elektrik aktivasyon haritaları yanı sıra sözde elektrokardiyogram (pseudo-EKG) simüle edilerek, tahmin hatası, niceleme ve kardiyak elektrofizyoloji bu hatayı onsimulations etkisini ölçerek önerilen yöntemin performansı değerlendirilmiştir. Insan kalpleri yokluğu nedeniyle, performans değerlendirme 13-15 daha önceki çalışmalardan elde köpek kalpleri kullanılarak yapılmıştır. Kestirim hatası eğim açıları 16, açısal ölçümler epicardialsurface paralel kesilir performedon doku bölümleri vardır histoloji ve followingthe geleneği ile hesaplanmıştır. AngleBetween lif yönü ve epikardiyal teğet düzlem generallysmall 17, 18, ​​olduğundan tamamen kendi eğim açısı kullanılarak fiberdirection anlatan bilgi kaybı önemsizdir. Comput içinmodellerde önceden 19, 20, ve kardiyak doku kurulan matematiksel teknikler ve deneysel veriler 21-25 dayalı temsil edildi bildirildiği gibi ational simülasyonları, görüntü tabanlı modeller inşa edilmiştir. Sinüs ritmi bir S1-S2 uyarım protokolü 27 tarafından purkinje ağı 26 ve ventriküler taşikardi, kaynaklı kopyalayan aktivasyonu ile simüle edilmiştir. Pseudo-EKG&#39;si 28 hesaplanan ve ortalama mutlak sapma (MAD) metrik 29 kullanılarak karşılaştırıldı.

<table border="1"><tbody><tr><td> LDDMM </td><td> Johns Hopkins University </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> Mathworks, Inc </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 </td><td> Ulusal Sağlık Enstitüleri </td><td></td><td> <a href="http://rsbweb.nih.gov/ij/" target="_blank">http://rsbweb.nih.gov/ij/</a> </td></tr><tr><td> Tarantula </td><td> CAE Yazılım Çözümleri </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> Köpek görüntüleri </td><td> Johns Hopkins University </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

Kardiyak tedaviye kişiselleştirme amaçlı kalp (dis) fonksiyonun Hastaya özel simülasyonlar klinik miyokard lifi yönelimleri elde etmek için in vivo görüntüleme teknolojisinde yokluğunda tarafından engellenmektedir. Bu projenin amacı, hastanın kalp geometrileri in vivo görüntülerini gelen kardiyak lif yönelimleri tahmin etmek için bir metodoloji geliştirmekti. Ventrikül geometrisi ve lif açısının doğru bir temsil yüksek çözünürlüklü ex vivo manyetik yapısal rezonans (MR) ve atlas olarak adlandırılan normal bir insan kalbi, difüzyon tensör (DT) MR görüntüleri, sırasıyla, yeniden inşa edildi. Bir hastanın kalp Ventriküler geometrisi vivo bilgisayarlı tomografi (BT) görüntü bir mesafede, yarı otomatik segmentasyon yoluyla, ekstre edildi. Görüntü dönüştürme algoritmaları kullanarak, atlas ventrikül geometrisi hastanın bu maç için deforme edilmiştir. Son olarak, şekil alan atlası elyaf orientat uygulandıiyonları hastanın lif açısının bir tahmin elde etmek. Lif tahminlerin doğruluğu altı normal ve üç başarısız köpek kalpleri kullanılarak değerlendirildi. Edinilen ve tahmini elyaf yönelimlerin eğim açıları arasındaki ortalama mutlak fark 15.4 ° idi. Sinüs ritmi ve ventriküler taşikardi, ventriküler aktivasyon haritaları ve pseudo-EKG Hesaplamalı simülasyonları geliştirilmesi için önünü açacak proje elde edilen klinik gözlemlenebilir level.The yeni anlayışlar tahmin ve kazanılmış elyaf yönelimleri arasında anlamlı farklılıklar olduğunu göstermiştir elektrofizyolojik müdahaleler konusunda kişiselleştirilmiş tanısında hekim ve kararlar yardımcı olabilir kalbin hastaya özgü modelleri.

Şekil 11, AC, normal ve başarısız kalplerde hem de tahmin edilen DTMRI-türevi lif açısının aerodinamik görsel gösterir. Nitel muayene tahmini elyaf yönelimleri DTMRI türevi olanlar ile iyi uyum gösterir. Panel D kalp 1 geometri üzerine bindirilmiş, gösterir, normal kalpte &#39;eğim açısı hata dağılımı, tüm beş tahminler arasında ortalama. Panel E kalbin 1 geometri üzerine bindirilmiş kalpleri &#39;eğim açısı, başarısız hata payı ortalama dağılımını göstermekte...

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

Kişiselleştirilmiş modelleme için hastanın kalp geometrileri in vivo görüntülerini gelen ventriküler lif yönelimleri tahmin etmek için bir metodoloji açıklanmaktadır. Metodolojinin Doğrulama normal kullanım ve köpek kalpleri göstermek başarısız gerçekleştirilen bir klinik gözlemlenebilir düzeyinde tahmin ve kazanılmış elyaf yönelimleri arasında anlamlı farklılıklar olduğu.

Kalp Hastaya özel Modelleme: Ventriküler Fiber Yönelimlerin Tahmini

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 Görüntüleme.  Johns Hopkins University. Kişiselleştirilmiş modelleme için hastanın kalp geometrileri in vivo görüntülerini gelen ventriküler lif yönelimleri tahmin etmek için bir metodoloji açıklanmaktadır. Metodolojinin Doğrulama normal kullanım ve köpek kalpleri göstermek başarısız gerçekleştirilen bir klinik gözlemlenebilir düzeyinde tahmin ve kazanılmış elyaf yönelimleri arasında anlamlı farklılıklar olduğu.

Video: 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.

Yüksek çözünürlüklü Fiber-optik Mikroendoskopi In situ Hücresel Görüntüleme

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

Biyomühendislik

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.

Çok parametreli Langendorff perfüze Tavşan Kalp Optik Haritalama

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.

Etkileşimli, hastanın özel modelleri kullanarak derin beyin stimülasyonu tedavisi için nöronal Fiber yolları hedefleme

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.

Fare kalp çalışma için ışık sayfalık floresans mikroskobu

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.

Atriyoventriküler kalp kapakları biaxial mekanik karakterizasyonu

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.

İzole Murine Ventriküler Miyositlerin Optik Görüntülemesi

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 Ekokardiyografi Kullanılarak Sol Ventrikül Yapısı ve İşlevinin Değerlendirilmesi

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.

Beyin Tümörü Cerrahisi Planlaması için Ultrason ve X-Ray Kontrastı ile Hastaya Özel Polivinil Alkol Phantom İmalatı

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.

Hastaya Özgü 3D Baskılı Akciğer Modelleri Kullanılarak Bölgesel Pulmoner Birikimin Değerlendirilmesi

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.

Kardiyovasküler Manyetik Rezonans Görüntüleme ile Fare Kalbi Sol Ventrikül fonksiyonu, Miyokard Zorlanması ve Hemodinamik Kuvvetlerin Nicelemesi

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