저자는 생체 모방 공학 및 Bioinspired 공학에 대한 GW 센터 (코 브레)에서 NSF 부여 CBET-0909678 및 자금 지원을 인정합니다. 우리의 지원을위한 실험실 씨 마티유 Barraja에 도움 씨 크리스토퍼 Popma 씨 리앤 Penna 씨 섀넌 칼라 씨 Shadman 후세인 씨 모하메드 R. Najjari 및 양 제시카 Hinke을 학생들에게 감사 CAD 도면.

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관심 없음 충돌 선언하지 않습니다.

이 논문에 제시된 프로토콜은 입자 영상 속도계 기술 (PIV)과 일관된 구조 검출 방법, 즉., 연속 웨이블릿 변환을 사용하여 고 충실도 실험 데이터의 취득을 설명합니다 <img alt="식 (1)" src="https://neuron2.jove.com/files/ftp_upload/51288/51288eq1.jpg" /> , 소용돌이 및 전단 지배 흐름의 식별에 적합합니다. 이상화 &quot;유형 IV&quot;골절의 존재 생리 유입에서 실험 데이터의 분석 밝혀 그 단순한 유체 다이내믹 이론에...

보조 유동 구조는 만곡 된 파이프 및 채널과 같은 곡률 내부 유동 형상에서 발생하는 선회 흐름 패턴이다. 이러한 선회 구조 인한 원심력, 역 압력 구배 유입 특성의 결합 작용으로 발생한다. . 3 차 유동 모폴로지 크게 박동에 의해 영향 - 일반적으로, 보조 유동 구조 및 진동형 유입 조건에서 대칭 Dean- 및 라인 씨 형 와류가 1 정상 유입 하에서 대칭 딘 형 와류 같은 만곡 관의 평면 단면에 나타나는 타악기의 여러 고조파, 생리 유입 조건. 이러한 구조는 1 유동 비 생리적 (정상 및 진동)에 비해 현저하게 다른 크기 강도 형상 특성을 확보 -. 6 동맥 죽상 경화 병변의 발달 영역에 고주파 전단 진동의 존재에 의해 영향을 낮은 평균 전단 (27) (28)를 경험 </suP&gt;. 보조 유동 구조는 질병 예컨대 아테롬성 동맥 경화증 및 가능의 진행에 영향 인해 벽 전단 응력과 혈액 유래 입자의 노출 시간을 변경함으로써 박동성 혈류 내피 반응을 매개 할 수있다. 죽상 경화증에 대한 일반적인 치료는 폐색 병변 동맥 협착에 기인하는 합병증은 스텐트 이식이다. 스텐트 골절은 또한 의료 등의 스텐트 내 재 협착과 같은 합병증 (ISR), 스텐트 혈전증과 동맥류 형성 9로 이어질 이식 된 스텐트의 구조적인 실패입니다 -. 13 스텐트 골절 다양한 실패 &quot;유형 I-에-IV&quot;로 분류되어, 특징 &quot;유형 IV&quot;가 가장 높은 임상 심각도를 특징 및 스텐트 조각 (14)의 선형 ​​변위와 함께 스텐트 스트럿의 전체 횡 골절로 정의된다. 본 연구에서 제시된 프로토콜은 experimenta 설명곡선 동맥 모델의 이상화 된 &quot;타입 IV&quot;스텐트 골절 하류 보조 유동 구조의 시각화 리터 방법. 제안 된 프로토콜은 다음과 같은 네 가지 필수 기능을 가지고 있습니다 : 설계 및 실험실 규모 스텐트 모델 제작 : 스텐트의 기하학적 설명 니티놀 와이어 (29) (니켈 및 티타늄의 합금)을 사용하여 자체 팽창 나선 (스프링 또는 나선) 세트 얽혀 연관 될 수있다. 스텐트와 지주 지름의 길이는 임상 주입 5 중에 발생한 동맥 병변의 길이 규모에 좌우된다. 파라 메트릭 지주 직경의 변화와 권선 (또는 피치)의 상승은 다양한 기하학적 구성의 스텐트에 연결됩니다. 3D 인쇄를 위해 선택된 스텐트 설계 파라미터의 요약은 표 1에 제시되어있다. 혈액 아날로그 작동 유체의 제조는 유사한만곡 동맥 검사부 광학 액세스 속도 비 침습성 측정을 위해 요구된다 : 혈액의 동점도 시험 부의 굴절률. 따라서, 인간의 혈액을 일치하는 이상적인 굴절률 혈관 모델 인덱스 동적 점도와 함께 작동 유체 뉴턴 혈액 모방 16 정확한 혈류 측정을 얻기 위해 사용된다 -. (18) (30)를 본 연구에 사용 된 작동 유체는보고 독일어 등으로. (2006), (부피 기준) 79 % 포화 수성 요오드화 나트륨 (NaI를), 20 % 순수 글리세롤, 1 %의 물 (16)로 구성된 것이다. 두 개의 구성 요소의 2 차원 입자 화상 속도계 (2C-2D PIV)를 사용하여 코 히어 런트 보조 유동 구조의 검출을위한 실험 구성은 : 실험 하류 다양한 평면의 단면 위치에서의 위상 평균 이차 유동 속도 데이터를 수집하도록 설계되었다 STR의 조합aight 및 구현 만곡 스텐트 부분 이상화 된 &quot;타입 IV&quot;스텐트 골절 5, 6, 9, 14. 입자상 속도계 (PIV) 기술을 이용하여 이차 유속 필드의 취득에 관한 프로토콜 단계로 이루어지는 PIV 시스템을 포함 레이저 (광 시트) 소스 초점 흐름 특별한 상호 상관 전하 결합 소자 (CCD 센서 또는 카메라)과 트레이서 입자의 영역을 조명하기위한 광학 장치의 Δt (짧은 시간 간격 내에서 광 시트에 의해 조명 될 32, 31) 표 4를 참조하십시오. 프로토콜의 단계에서는 가정 다음 우선, 2 화면 단일 노출 기록하여 화상을 평가하는 이성, 이차원 (2C-2D) PIV 시스템의 교정, 실험 장치. 둘째, 2C-2D PIV 시스템은 각각의 기록 동안에 획득 개의 영상 프레임 사이의 상호 상관을 수행하여 추적 된 입자의 평균 변위를 계산한다. BRPIV 사양 및 이미지 수집 소프트웨어의 IEF 요약 재료 및 장비 표에 표시됩니다. 셋째, 레이저를 작동하는 데 필요한 모든 안전 예방 조치는 호스트 기관에 의해 제공되는 가이드 라인에 따라 훈련 기관 담당자가 따른다. 저자는 참고 문헌을 제시한다. , 에어로 하이드로 미세 유체 역학 상관 피크 검출 변위 추정 물질 추적 입자의 밀도, 측정 잡음 및 정확도의 구현 기능 및 PIV 기술의 응용에 대한 전체적인 이해를 위해 31, 32. 또한, 레이저 및 카메라가 PIV 데이터 취득 시스템 (도 3a) 및 데이터 처리 소프트웨어에 의해 제어 될 수 있다는 점에 유의하라. 데이터 수집 및 후 처리 히어 런트 검출 구조의 경우 : 2C-2D PIV를 사용하여 위상 차의 평균 유속의 측정은 이하의 프로토콜 정보를 이용하여 생성 하였다. 후 처리<html> 연속 웨이블렛 변환을 상기 데이터의 ING는 다음과 같은 세 가지 방법을 이용하여 간섭 보조 유동 구조 검출을 포함 <img alt="식 (1)" src="/files/ftp_upload/51288/51288eq1.jpg" /> 5, 6, 19-24, 26. 저자는 속도 구배 텐서 본질적으로하는 3 × 3 행렬을 참고 <img alt="식 (2)" src="/files/ftp_upload/51288/51288eq2.jpg" /> . 이 프로토콜 (2C-2D PIV 기술)에서 이차원 실험 측정치를 획득하는 방법을 제시한다. 따라서, 속도 구배 텐서에 대한 모든 실험적인 접근이 방법을 사용하여 달성 할 수 없습니다. 각 화소의 속도 구배 텐서 <img alt="식 (3)" src="/files/ftp_upload/51288/51288eq3.jpg" /> PIV 이미지 <img alt="식 (4)" src="/files/ftp_upload/51288/51288eq4.jpg" /> 2 × 2 행렬이어야한다, <img alt="식 (5)" src="/files/ftp_upload/51288/51288eq5.jpg" /> . 는 z 성분 와도quation 6 &quot;SRC =&quot;/ 파일 / ftp_upload / 51288 / 51288eq6.jpg &quot;&gt; 각 픽셀에 대한 / <img alt="식 (7)" src="/files/ftp_upload/51288/51288eq7.jpg" /> 속도 구배 텐서의 반대 칭 부분을 사용하여 계산된다 <img alt="식 (8)" src="/files/ftp_upload/51288/51288eq8.jpg" /> . 그 결과 와도의 2 차원 배열이됩니다 <img alt="식 (9)" src="/files/ftp_upload/51288/51288eq9.jpg" /> 그는 등고선 플롯으로 시각화 할 수 있습니다. 저자는 강력하게 심판을 제안한다. 소용돌이 발산, 변형율 및 코히 런트 검출 구조의 기술 향상을 향한 속도 구배 텐서에 웅변 토의 실험 액세스 25. 또한 저자들은 참조를 상기 간섭 구조 검출 방법 간의 상호 관계를 탐구하고 제안하지 않는다. 그 주제에 대한 종합 토론 23, 24. 프로토콜의 단계의 초점은 보조 흐름 (와류)의 양적 식별이다 일(또한 일관된 구조라고도 함) ructures. 코 히어 런트 검출 구조 즉 세 가지 방법., <img alt="식 (10)" src="/files/ftp_upload/51288/51288eq10.jpg" /> 그리고 잔물결이 와도을 변환 <img alt="식 (11)" src="/files/ftp_upload/51288/51288eq11.jpg" /> 이상화 된 &quot;타입 IV&quot;스텐트 골절 하류 보조 유동 구조의 멀티 - 스케일 멀티 강도 발생의 검출을 향해 속도 필드 데이터에 적용된다. 그만큼 <img alt="식 (12)" src="/files/ftp_upload/51288/51288eq12.jpg" /> 와도 텐서의 유클리드 놈이 균주 19, 23, 속도 24 국지적 속도 구배 행렬은 대칭 적 (스트레인 비율)과 항 - 대칭 (회전) 부분으로 분해되는 것을 지배하는 경우, 공간 영역으로서 와류를 정의한다. 변형율 행렬의 고유 값 계산된다; <img alt="식 (13)" src="/files/ftp_upload/51288/51288eq13.jpg" /> . 변형율의 규범이어서 계산된다; <img의 고도 = &quot;식 (14)&quot;SRC = &quot;/ 파일 / ftp_upload / 51288 / 51288eq14.jpg&quot;/&gt;. 소용돌이는 반 대칭 부분에서 계산된다. Enstrophy 또는 z 성분의 소용돌이의 광장, <img alt="식 (15)" src="/files/ftp_upload/51288/51288eq15.jpg" /> )를 계산한다. 그만큼 <img alt="식 (16)" src="/files/ftp_upload/51288/51288eq16.jpg" /> 마지막으로 계산이고; <img alt="식 (17)" src="/files/ftp_upload/51288/51288eq17.jpg" /> . 전체 집합의 윤곽 플롯 <img alt="식 (18)" src="/files/ftp_upload/51288/51288eq18.jpg" /> 의 이소 - 지역으로 <img alt="식 (19)" src="/files/ftp_upload/51288/51288eq19.jpg" /> 이차 흐름 구조 (19)가 표시됩니다. 그만큼 <img alt="식 (20)" src="/files/ftp_upload/51288/51288eq20.jpg" /> 또한 &#39;소용돌이 힘 &quot;으로 알려진 로컬 속도 구배 텐서의 중요한 점 분석에 의해 수행되는 와류 식별 방법 및 해당 고유 20-24 <strong&gt;. 각 화소의 속도 구배 텐서의 고유치 <img alt="식 (21)" src="/files/ftp_upload/51288/51288eq21.jpg" /> 계산된다. 고유 값은 형식이어야합니다 <img alt="식 (22)" src="/files/ftp_upload/51288/51288eq22.jpg" /> . 의 윤곽 플롯 <img alt="식 (23)" src="/files/ftp_upload/51288/51288eq23.jpg" /> 의 이소 - 지역으로 <img alt="식 (24)" src="/files/ftp_upload/51288/51288eq24.jpg" /> (22) - 이차 흐름 구조 (20)가 표시됩니다. 방법을 웨이블릿 변환하는 것은 물리적 및 스펙트럼 공간에서 부드러움이있는 분석 기능 (또는 웨이브)를 사용, 허용 (또는 제로 평균을 가지고)와 유한이 <img alt="식 (25)" src="/files/ftp_upload/51288/51288eq25.jpg" /> 5, 6, 26. A는 팽창 된 또는 컨벌루션 저자는 차원 와도 필드 웨이블릿 수축 웨이블릿 변환 와도 <img alt="식 (26)" src="/files/ftp_upload/51288/51288eq26.jpg" /> 필드 c를 생성한다저울과 장점 (5, 6)의 넓은 범위, 2 차원 웨이블릿 변환 와도 필드 (26). 섀넌 엔트로피와 일관된 구조 omprising 모든 간섭 구조가 적절하게 해결하는 최적의 웨이블렛 스케일을 추정하기 위해 계산된다. 이 엔트로피 추정 확률의 세트를 포함 <img alt="식 (27)" src="/files/ftp_upload/51288/51288eq27.jpg" /> 각 픽셀에 대한 <img alt="식 (21)" src="/files/ftp_upload/51288/51288eq21.jpg" /> 되도록 <img alt="식 (28)" src="/files/ftp_upload/51288/51288eq28.jpg" /> , 정규화 된 사각형 위치 m의 픽셀과 관련된 와도 계수, n은 5, 6. 절차상의 단계는 그림 6에 그래픽으로 표시됩니다. 웨이블릿의 선택에 배치 제한은 참고 문헌에 자세히 표시됩니다. 26이 프로토콜 단계는 2D Ricker 웨이블릿을 이용하여 코 히어 런트 검출 구조를위한 절차를 설명한다. 이 사용 w에 대한 정당성선회 패턴 매칭을위한 avelet은 참고 문헌에 제시되어있다. 도 5,도 6과 관련 참조 내에 들었다.

<table border="0" cellpadding="0" cellspacing="0" width="698">
	<tbody>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Acrylic tubes and sheet</td>
			<td style="width:155px;">McMaster-Carr Supply Company</td>
			<td style="width:119px;"></td>
			<td style="width:208px;">Inlet and outlet pipes and, material of the curved artery test section</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Object24 Desktop 3D printer</td>
			<td style="width:155px;">Stratasys</td>
			<td style="width:119px;"></td>
			<td style="width:208px;">Desktop rapid prototyping machine. http://www.stratasys.com/.&#160;</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">VeroWhitePlus Opaque material</td>
			<td style="width:155px;">Stratasys</td>
			<td style="width:119px;"></td>
			<td style="width:208px;">Building material for Object24 Desktop 3D printer</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">Fullcure 705</td>
			<td style="width:155px;">Stratasys</td>
			<td style="width:119px;"></td>
			<td style="width:208px;">&#160;Non-toxic gel-like photopolymer Support material for Object24 Desktop 3D printer</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Ubbelhode viscometer</td>
			<td style="width:155px;">Cole Parmer</td>
			<td>YO-98934-12</td>
			<td style="width:208px;">Toward measurement of kinematic viscosity of the blood-analog fluid</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">VELP scientifica - ESP stirrer&#160;</td>
			<td style="width:155px;">VELP Scientifica</td>
			<td>F206A0179</td>
			<td style="width:208px;">Magnetic stirrer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Ohaus Scout Pro SP 601&#160;</td>
			<td style="width:155px;">The Lab Depot</td>
			<td>SP4001</td>
			<td style="width:208px;">Weigh scale</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Refractometer</td>
			<td>Atago</td>
			<td style="width:119px;">PAL-RI</td>
			<td style="width:208px;">Toward measurement of refractive index of blood-analog fluid</td>
		</tr>
		<tr height="105">
			<td height="105" style="height:105px;width:216px;">Beakers, pipettes, syringes and spatula</td>
			<td style="width:155px;">Sigma-Aldrich&#160;</td>
			<td style="width:119px;">CLS710110,&#160; CLS10031L, CLS71015, CLS71011 Z193216</td>
			<td style="width:208px;">Toward handling materials required for blood-analog solution preparation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Sodium Iodide</td>
			<td style="width:155px;">Sigma-Aldrich</td>
			<td>383112-2.5KG&#160;</td>
			<td style="width:208px;">Crystalline</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Glycerol</td>
			<td style="width:155px;">Sigma-Aldrich</td>
			<td>G5516-1L</td>
			<td style="width:208px;">Liquid</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Deionized Water</td>
			<td style="width:155px;">-</td>
			<td style="width:119px;">-</td>
			<td style="width:208px;">Liquid</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Sodium thiosulfate anhydrous</td>
			<td style="width:155px;">Sigma-Aldrich</td>
			<td>72049-250G</td>
			<td style="width:208px;">Powder</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">PIV Recording medium</td>
			<td style="width:155px;">&#160;LaVision&#160;</td>
			<td style="width:119px;">Imager Intense 10Hz</td>
			<td style="width:208px;">PIV Image acquisition CCD camera</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">PIV Illumination source</td>
			<td style="width:155px;">New Wave Research</td>
			<td style="width:119px;">Solo III-15</td>
			<td style="width:208px;">PIV Laser source, Nd:YAG laser, 532 nm, dual pulse 70 mJ/pulse</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">PIV Imaging software</td>
			<td style="width:155px;">&#160;LaVision&#160;</td>
			<td style="width:119px;">DaVis 7.2&#160;</td>
			<td style="width:208px;">PIV data acquisition and instrument control&#160;</td>
		</tr>
		<tr height="211">
			<td height="211" style="height:211px;width:216px;">PIV Seeding material</td>
			<td style="width:155px;">Thermo-scientific&#160;&#160;</td>
			<td style="width:119px;">Flouro-Max</td>
			<td style="width:208px;">Red fluorescent polymer microspheres (&#8776; 7 &#181;m); Dry dyed polystyrene (DVB) fluorescent microspheres emit bright and distinct colors when illuminated by the light of shorter&#160; wavelengths than the emission wavelength.&#160;</td>
		</tr>
	</tbody>
</table>

experimental investigation of secondary flow structures downstream of a model type iv stent failure in a 180&#176; curved artery test section

인간의 혈관의 동맥 네트워크는 복잡한 형상 (지점, 곡률과 비틀림)에 보편적으로 존재하는 혈관 구성되어 있습니다. 보조 유동 구조에 의한 원심력, 역 압력 구배 유입 특성의 결합 작용으로 만곡 동맥에 발생하는 선회 흐름 패턴이다. 이러한 흐름 모폴로지 크게 박동 및 생리 학적 유입 조건의 여러 고조파의 영향과 1 흐르는 비 생리적 (정상 및 진동)에 비해 크기 강도 형 특성이 크게 변화된다 - (7). 보조 유동 구조 궁극적 죽상 경화증, 재 협착, 혈소판 감작 및 혈전증 (4)의 진행 방향으로 혈액 유래 입자 벽 전단 응력 및 노출 시간에 영향을 미칠 수 - 6, 8-13 따라서, 실험에 따라 이러한 구조를 검출하고 특성화하는 능력. -controlled 조건은 precurs입니다임상 연구를 촉진합니다. 죽상 동맥 경화증에 대한 일반적인 수술 적 치료는 탁 트인 혈액 흐름에 대한 협착 동맥을 열어 스텐트 시술이다. 그러나 때문에 스텐트 설치에 수반 흐름 교란 멀티 규모의 이차 흐름 모폴로지 (4) 결과 -. 6 이러한 일관성의 비대칭 손실로 점진적으로 더 높은 차수의 복잡성은 마주 교란 흐름 5 세 미만 계속되는 스텐트 장애에 의해 유발 될 수있다. 이러한 스텐트 실패는 실패의 고려 사항 및 임상 적 중증도 (14)에 따라 &quot;유형 I-에-IV&quot;로 분류되고있다. 본 연구는 만곡 동맥 스텐트 모델 횡 골절 및 골절 부의 선형 변위 ( &quot;타입 IV&quot;)을 완료하기 때문에 복잡한 보조 유동 구조의 실험 연구를위한 프로토콜을 제공한다. 실험 방법은 입자 화상 속도계의 구현을 포함한다 (도 2C-2전형적인 경동맥 유입 파형 D PIV)는 기술, 굴절률 위상 평균 측정치 (15)에 대한 작동 유체 혈액 아날로그 일치 -. 18 차 유동 구조의 양적 식별이 흐름 물리학의 개념, 중요한 점 이론과 소설을 사용하여 달성되었다 26 - PIV 실험 데이터 5, 6, 19에 적용되는 알고리즘을 웨이블릿 변환.

도 7A-D에 제시된 결과 (참조 :도 5, 6)도 3a에 도시 2C-2D PIV 시스템으로부터 취득한 후 처리 이차 유속 데이터 후에 발생 하였다. 이상화 된 &quot;타입 IV&quot;스텐트 골절 만곡 동맥 시험 부에 공급되는 유입 상태는도 4b에 도시 된 경동맥 파형이다. 우리의 이전 연구 Womersley 번호의 특정 범위 내에 유입 맥동 파형?...

Watch this Scientific Journal Video about Experimental Investigation of Secondary Flow Structures Downstream of a Model Type IV Stent Failure in a 180Ã‚Â° Curved Artery Test Section at JoVE.com

Experimental Investigation of Secondary Flow Structures Downstream of a Model Type IV Stent Failure in a 180&#176; Curved Artery Test Section

Stent implants in stenosed arterial curvatures are prone to "Type IV" failures involving the complete transverse fracture of stents and linear displacement of the fractured parts. We present a protocol for detection of secondary flow (vortical) structures in a curved artery model, downstream of clinically relevant "Type IV" stent failures.

180 ° 곡선 동맥 테스트 섹션에서 모델 유형 IV 스텐트 실패의 다운 스트림 보조 흐름 구조의 실험 조사

The arterial network in the human vasculature comprises of ubiquitously present blood vessels with complex geometries (branches, curvatures and ...

experimental-investigation-secondary-flow-structures-downstream-model

Research

JoVE Journal

Bioengineering

11.5K 조회수.  The George Washington University. Stent implants in stenosed arterial curvatures are prone to "Type IV" failures involving the complete transverse fracture of stents and linear displacement of the fractured parts. We present a protocol for detection of secondary flow (vortical) structures in a curved artery model, downstream of clinically relevant "Type IV" stent failures.

비디오: Experimental Investigation of Secondary Flow Structures Downstream of a Model Type IV Stent Failure in a 180° Curved Artery Test Section

A Model of Disturbed Flow-Induced Atherosclerosis in Mouse Carotid Artery by Partial Ligation and a Simple Method of RNA Isolation from Carotid Endothelium

Despite the well-known close association, direct evidence linking disturbed flow to atherogenesis has been lacking. We have recently used a modified version of carotid partial ligation methods [1,2] to show that it acutely induces low and oscillatory flow conditions, two key characteristics of disturbed flow, in the mouse common carotid artery. Using this model, we have provided direct evidence that disturbed flow indeed leads to rapid and robust atherosclerosis development in Apolipoprotein E knockout mouse [3]. We also developed a method of endothelial RNA preparation with high purity from the mouse carotid intima [3]. Using this mouse model and method, we found that partial ligation causes endothelial dysfunction in a week, followed by robust and rapid atheroma formation in two weeks in a hyperlipidemic mouse model along with features of complex lesion formation such as intraplaque neovascularization by four weeks. This rapid in vivo model and the endothelial RNA preparation method could be used to determine molecular mechanisms underlying flow-dependent regulation of vascular biology and diseases. Also, it could be used to test various therapeutic interventions targeting endothelial dysfunction and atherosclerosis in considerably reduced study duration.

This describes a partial carotid ligation surgery, which causes disturbed flow conditions and subsequent atherosclerosis development (in two weeks) with intraplaque neo-vascularization (in four weeks) in the mouse common carotid artery. We also describe a novel method of RNA isolation from the carotid intima, providing high purity endothelial RNA.

부분 결합하여 마우스 경동맥 동맥에있는 방해 흐름 유발 죽상 경화증과 경동맥 내피로부터 RNA 분리의 간단한 방법의 모델

Despite the well-known close association, direct evidence linking disturbed flow to atherogenesis has been lacking. We have recently used a modified ...

연구

의학

Monitoring the Wall Mechanics During Stent Deployment in a Vessel

Clinical trials have reported different restenosis rates for various stent designs1. It is speculated that stent-induced strain concentrations on the arterial wall lead to tissue injury, which initiates restenosis2-7. This hypothesis needs further investigations including better quantifications of non-uniform strain distribution on the artery following stent implantation. A non-contact surface strain measurement method for the stented artery is presented in this work. ARAMIS stereo optical surface strain measurement system uses two optical high speed cameras to capture the motion of each reference point, and resolve three dimensional strains over the deforming surface8,9. As a mesh stent is deployed into a latex vessel with a random contrasting pattern sprayed or drawn on its outer surface, the surface strain is recorded at every instant of the deformation. The calculated strain distributions can then be used to understand the local lesion response, validate the computational models, and formulate hypotheses for further in vivo study.

Stent-induced arterial strain distributions are characterized using an optical surface strain measurement system. This visualization technique is used to gain insights into the impact of stent implantation on the host vessel.

선박의 스텐 트를 배포하는 동안 벽 역학 모니터링

Clinical trials have reported different restenosis rates for various stent designs1. It is speculated that stent-induced strain concentrations on the ...

생체공학

A Murine Model of Stent Implantation in the Carotid Artery for the Study of Restenosis

Despite the considerable progress made in the stent development in the last decades, cardiovascular diseases remain the main cause of death in western countries. Beside the benefits offered by the development of different drug-eluting stents, the coronary revascularization bears also the life-threatening risks of in-stent thrombosis and restenosis. Research on new therapeutic strategies is impaired by the lack of appropriate methods to study stent implantation and restenosis processes. Here, we describe a rapid and accessible procedure of stent implantation in mouse carotid artery, which offers the possibility to study in a convenient way the molecular mechanisms of vessel remodeling and the effects of different drug coatings.

A model of stent implantation in mouse carotid artery is described. Compared to other similar methods, this procedure is very rapid, simple and accessible, offering the possibility to study in a convenient way the vascular wall reaction to different drug-eluting stents and the molecular mechanisms of restenosis.

재 협착의 연구에 대한 경동맥 스텐트 시술의 쥐과 모형

Despite  the considerable progress made in the stent development in the last decades,  cardiovascular diseases remain the main cause of death in western ...

Imaging In-Stent Restenosis: An Inexpensive, Reliable, and Rapid Preclinical Model

Preclinical models of restenosis are essential to unravel the pathophysiological processes that lead to in-stent restenosis and to optimize existing and future drug-eluting stents.
A variety of antibodies and transgenic and knockout strains are available in rats. Consequently, a model for in-stent restenosis in the rat would be convenient for pathobiological and pathophysiological studies. 
In this video, we present the full procedure and pit-falls of a rat stent model suitable for high throughput stent research. We will show the surgical procedure of stent deployment, and the assessment of in-stent restenosis using the most elegant technique of OCT (Optical Coherence Tomography). This technique provides high accuracy in assessing plaque CSAs (cross section areas) and correlates well with histological sections, which require special and time consuming embedding and sectioning techniques. OCT imaging further allows longitudinal monitoring of the development of in-stent restenosis within the same animal compared to one-time snapshots using histology.

This video demonstrates how to use a preclinical inexpensive and reliable model to study pathobiological and pathophysiological processes of in-stent restenosis development. Longitudinal in vivo monitoring using OCT (Optical Coherence Tomography) and analysis of OCT images are also demonstrated.

이미징에서 스텐트 - Restenosis : 저렴한, 신뢰성 및 빠른 잠복기 모델

Preclinical models of restenosis are essential to unravel the pathophysiological processes that lead to in-stent restenosis and to optimize existing and ...

생물학

Ferromagnetic Bare Metal Stent for Endothelial Cell Capture and Retention

Rapid endothelialization of cardiovascular stents is needed to reduce stent thrombosis and to avoid anti-platelet therapy which can reduce bleeding risk. The feasibility of using magnetic forces to capture and retain endothelial outgrowth cells (EOC) labeled with super paramagnetic iron oxide nanoparticles (SPION) has been shown previously. But this technique requires the development of a mechanically functional stent from a magnetic and biocompatible material followed by in-vitro and in-vivo testing to prove rapid endothelialization. We developed a weakly ferromagnetic stent from 2205 duplex stainless steel using computer aided design (CAD) and its design was further refined using finite element analysis (FEA). The final design of the stent exhibited a principal strain below the fracture limit of the material during mechanical crimping and expansion. One hundred stents were manufactured and a subset of them was used for mechanical testing, retained magnetic field measurements, in-vitro cell capture studies, and in-vivo implantation studies. Ten stents were tested for deployment to verify if they sustained crimping and expansion cycle without failure. Another 10 stents were magnetized using a strong neodymium magnet and their retained magnetic field was measured. The stents showed that the retained magnetism was sufficient to capture SPION-labeled EOC in our in-vitro studies. SPION-labeled EOC capture and retention was verified in large animal models by implanting 1 magnetized stent and 1 non-magnetized control stent in each of 4 pigs. The stented arteries were explanted after 7 days and analyzed histologically. The weakly magnetic stents developed in this study were capable of attracting and retaining SPION-labeled endothelial cells which can promote rapid healing.

Our goals were to design, manufacture and test ferromagnetic stents for endothelial cell capture. Ten stents were tested for fracture and 10 more stents were tested for retained magnetism. Finally, 10 stents were tested in-vitro and 8 more stents were implanted in 4 pigs to show cell capture and retention.

내피 세포 캡처 및 유지에 대한 강자성 베어 메탈 스텐트

Rapid endothelialization of cardiovascular stents is needed to reduce stent thrombosis and to avoid anti-platelet therapy which can reduce bleeding risk. ...

4D Printed Bifurcated Stents with Kirigami-Inspired Structures

Branched vessels, typically in the form of the letter &#34;Y,&#34;&#160;can be narrowed or blocked, resulting in serious health problems. Bifurcated stents, which are hollow in the interior and exteriorly shaped to the branched vessels, surgically inserted inside the branched vessels, act as a supporting structure so that bodily fluids can freely travel through the interior of the stents without being obstructed by the narrowed or blocked vessels. For a bifurcated stent to be deployed at the target site, it needs to be injected inside the vessel and travel within the vessel to reach the target site. The diameter of the vessel is much smaller than the bounding sphere of the bifurcated stent; thus, a technique is required so that the bifurcated stent remains small enough to travel through the vessel and expands at the targeted branched vessel. These two conflicting conditions, that is, small enough to pass through and large enough to structurally support narrowed passages, are extremely difficult to satisfy simultaneously. We use two techniques to fulfill the above requirements. First, on the material side, a shape memory polymer (SMP) is used to self-initiate shape changes from small to large, that is, being small when inserted and becoming large at the target site. Second, on the design side, a kirigami pattern is used to fold the branching tubes into a single tube with a smaller diameter. The presented techniques can be used to engineer structures that can be compacted during transportation and return to their functionally adept shape when activated. Although our work is targeted on medical stents, biocompatibility issues need to be solved before actual clinical use.

Using a 3D printer, a shape memory polymer filament is extruded to form a branched tubular structure. The structure is patterned and shaped such that it can contract into a compact form once folded and then return to its formed shape when heated.

키리가미에서 영감을 받은 구조의 4D 인쇄 된 분기식 스텐트

Branched vessels, typically in the form of the letter &#34;Y,&#34;&#160;can be narrowed or blocked, resulting in serious health problems. Bifurcated ...

공학

In vitro Assessment of Aortic Regurgitation Using Four-Dimensional Flow Magnetic Resonance Imaging

Aortic regurgitation (AR) refers to backward blood flow from the aorta into the left ventricle (LV) during ventricular diastole. The regurgitant jet arising from the complex shape is characterized by the three-dimensional flow and high-velocity gradient, sometimes limiting an accurate measurement of the regurgitant volume using 2D echocardiography. Recently developed four-dimensional flow magnetic resonance imaging (4D flow MRI) enables three-dimensional volumetric flow measurements, which can be used to accurately quantify the amount of the regurgitation. This study focuses on (i) magnetic resonance compatible AR model fabrication (dilatation, perforation, and prolapse) and (ii) systematic analysis of the performance of 4D flow MRI in AR quantification. The results indicated that the formation of the forward and backward jets over time was highly dependent on the types of AR origin. The amount of regurgitation volume bias for the model types were -7.04%, -33.21%, 6.75%, and 37.04% compared to the ground truth (48 mL) volume measured from the pump stroke volume. The largest error of the regurgitation fraction was around 12%. These results indicate that careful selection of imaging parameters is required when absolute regurgitation volume is important. The suggested in vitro flow phantom can easily be modified to simulate other valvular diseases such as aortic stenosis or bicuspid aortic valve (BAV) and can be used as a standard platform to test different MRI sequences in the future.

In vitro Assessment of Aortic Regurgitation Using Four-Dimensional Flow Magnetic Resonance Imaging

Aortic regurgitation is an aortic valve heart disease. This manuscript demonstrates how four-dimensional flow magnetic resonance imaging can evaluate aortic regurgitation using in vitro heart valves mimicking aortic regurgitation.

시험관내 사차원 유동 자기 공명 영상을 이용한 대동맥 역류 평가

Aortic regurgitation (AR) refers to backward blood flow from the aorta into the left ventricle (LV) during ventricular diastole. The regurgitant jet ...

Particle Image Velocimetry Investigation of Hemodynamics via Aortic Phantom

Aortic valve dysfunction and stroke have recently been reported in transcatheter aortic valve implantation (TAVI) patients. Thrombus in the aortic sinus and neo-sinus due to hemodynamic changes has been suspected. In vitro experiments help investigate the hemodynamic characteristics in the cases where an in vivo assessment proves to be limited. In vitro experiments are also more robust, and the variable parameters are controlled readily. Particle image velocimetry (PIV) is a popular velocimetry method for in vitro studies. It provides a high-resolution velocity field such that even small-scale flow features are observed. The purpose of this study is to show how PIV is used to investigate the flow field in the aortic sinus after TAVI. The in vitro setup of the aortic phantom, TAVI for PIV, and the data acquisition process and post-processing flow analysis are described. The hemodynamic parameters are derived, including the velocity, flow stasis, vortex, vorticity, and particle residence. The results confirm that in vitro experiments and PIV help investigate the hemodynamic features in the aortic sinus.

Particle Image Velocimetry Investigation of Hemodynamics via Aortic Phantom

The present protocol describes particle image velocimetry (PIV) measurements performed to investigate the sinus flow through the in vitro setup of the transcatheter aortic valve (TAV). The hemodynamic parameters based on velocity are also determined.

대동맥 팬텀을 통한 혈역학의 입자 이미지 Velocimetry 조사

Aortic valve dysfunction and stroke have recently been reported in transcatheter aortic valve implantation (TAVI) patients. Thrombus in the aortic sinus ...

<meta charset="utf8"></head><body> 관상동맥 기계적 특성을 정량화하기 위한 IVUS 기반 계산 방법

Intravascular Ultrasound Image-Based Finite Element Modeling Approach for Quantifying In Vivo Mechanical Properties of Human Coronary Artery

Quantifying the mechanical properties of coronary arterial walls could provide meaningful information for the diagnosis, management, and treatment of coronary artery diseases. Since patient-specific coronary samples are not available for patients requiring continuous monitoring, direct experimental testing of vessel material properties becomes impossible. Current coronary models typically use material parameters from available literature, leading to significant mechanical stress/strain calculation errors. Here, we would introduce a finite element model-based updating approach (FEMBUA) to quantify patient-specific in vivo material properties of coronary arteries based on medical images. In vivo cine intravascular ultrasound (IVUS) and virtual histology (VH)-IVUS images of coronary arteries were acquired from a patient with coronary artery disease. Cine IVUS images showing the vascular movement over one cardiac cycle were segmented, and two IVUS frames with maximum and minimum lumen circumferences were selected to represent the coronary geometry under systolic and diastolic pressure conditions, respectively. VH-IVUS image was also segmented to obtain the vessel contours, and a layer thickness of 0.05 cm was added to the VH-IVUS contours to reconstruct the coronary geometry. A computational finite element model was created with an anisotropic Mooney-Rivlin material model used to describe the vessel's mechanical properties and pulsatile blood pressure conditions prescribed to the coronary luminal surface to make it contract and expand. Then, an iterative updating approach was employed to determine the material parameters of the anisotropic Mooney-Rivlin model by matching minimum and maximum lumen circumferences from the computational finite element model with those from cine IVUS images. This image-based finite element model-based updating approach could be successfully extended to determine the material properties of arterial walls in various vascular beds and holds the potential for risk assessment of cardiovascular diseases.

<meta charset="utf8"></head><body>인간 관상동맥의 생체 내 기계적 특성을 정량화하기 위한 혈관 내 초음파 이미지 기반 유한 요소 모델링 접근 방식

In vivo cine intravascular ultrasound images show the coronary cross-sectional movement corresponding to different pressure loading conditions. Based on a finite element model, an iterative scheme was employed to determine the patient-specific mechanical properties of coronary arteries in vivo by matching coronary motion from the computational model and medical images.

인간 관상동맥의 생체 내 기계적 특성을 정량화하기 위한 혈관 내 초음파 이미지 기반 유한 요소 모델링 접근 방식 

Quantifying the mechanical properties of coronary arterial walls could provide meaningful information for the diagnosis, management, and treatment of ...