The authors acknowledge support from the Department of Diagnostic Imaging at the H. Lee Moffitt Cancer Center and Research Institute.

The following protocol follows the departmental clinical guidelines and is adherent to the institution&#8217;s human research ethics guidelines.
1. Prepare for MRI Data Acquisition
<ol>
	<li>Conduct a safety screening.
	<ol>
		<li>Evaluate for renal impairment8.
		<ol>
			<li>Avoid gadolinium contrast in patients with stage 4 or 5 chronic kidney disease (estimated glomerular filtration rate &#60;30 mL/min/1.71 m2) not on chronic dialysis, patients with end-stage renal disease on chronic dialysis, and patients with known or suspected acute kidney injury due to concerns for NSF.</li>
		</ol>
		</li>
		<li>Determine necessity for sedation9. 
		NOTE: Moderate sedation or general anesthesia allows completion of the examination for patients suffering from anxiety or claustrophobia or pediatric patients.
		<ol>
			<li>Administer a lorazepam tablet up to 1 mg orally prior to scanning for patients with claustrophobia. Driving or machinery operation after medication administration is contraindicated.</li>
		</ol>
		</li>
		<li>Evaluate for implanted devices9.
		<ol>
			<li>Perform a careful review of the patient&#8217;s history and safety to identify implanted devices that may be hazardous in the CMR environment or create image artifact.</li>
			<li>Determine MR compatibility of patient implanted devices. Each case is reviewed for risks and benefits. The proper personnel are required to be present during the examination if CMR is to be performed in patients with non-MR safe devices.</li>
			<li>Obtain radiographs to assist with screening, particularly orbit radiographs when there is possible history of metal fragments within the eye. Perform posterior-anterior radiographs with eyes up, eyes down, and a lateral view.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Provide patient instructions.
	<ol>
		<li>Deliver breathing instructions10.
		<ol>
			<li>Perform breath holding at end expiration as reproducibility is higher compared to inspiratory breath holds. For CMR, use the typical breath hold command: &#8220;breathe in, breathe out, stop breathing&#8221;.</li>
			<li>Provide patient with headphones connected to the technologist microphone so commands can be efficiently conveyed.</li>
			<li>Perform free-breathing protocol when patient is unable to hold-breath for the exam due to sedation or medical condition. Free breathing protocols increase the number of averages (excitations) up to 4 and allow adequate free breathing image acquisition. Free breathing protocols can be selected from typical scanner exam libraries.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Setup physiological monitoring10.
	<ol>
		<li>Place electrocardiogram (ECG) leads in optimal positions on the left chest, and confirm adequate ECG signal.</li>
	</ol>
	</li>
	<li>Position the patient on the MRI scanner.
	<ol>
		<li>Ensure an appropriate surface coil size is chosen to maximize the signal-to-noise ratio over the heart. Often a dedicated cardiac coil is selected for optimal performance. Signal to noise correlates directly with image quality and is visually evident during scanning</li>
		<li>Reduce field of view to maintain adequate spatial resolution. FOV is changed in the scanner settings directly and is dependent on patient size</li>
	</ol>
	</li>
</ol>
2. Acquire the MRI Data [Cardiac MR without and with IV Contrast Limited] Focused Scan to Evaluated Potential Cardiac Thrombus
NOTE: Basic scan sequences are often loaded by the MRI technologist from scan libraries that are present on each MRI scanner. Standard cardiac scan prescription and orientations are also considered routine operating tasks for MRI technologists.
<ol>
	<li>Obtain the Scout T1-weighted fast spin-echo including the trans-axial localizing stack1. 
	NOTE: This constitutes the first scan for each MRI exam and allows further sequences to be prescribed using spatial localization.</li>
	<li>Obtain the Bright-blood, cine SSFP gradient-echo &#8211; axial stack with full heart coverage. This sequence offers the most consistent mass delineation and correlation with other radiology studies.
	<ol>
		<li>Obtain short axis, 2 chamber, 3 chamber, and 4-chamber planes as needed depending on clinical indications. Scan plane prescriptions are discussed in detail in Boegart11. 
		NOTE: These acquisitions are non-dependent on flow effects which allow for short TR, improve temporal resolution, and permit determination of mobility of a thrombus. SSFP provides high SNR and CNR due to intrinsic contrast properties between myocardium and blood pool.</li>
	</ol>
	</li>
	<li>Perform the tissue characterization module1,2,3,11,12.
	<ol>
		<li>Obtain the black-blood triple inversion recovery. 
		NOTE: This provides excellent contrast resolution for determining the size and the extent of the mass. It is useful for characterizing myocardial edema associated with mass or cystic component of mass and in detecting fat within the mass.
		<ol>
			<li>Obtain the black-blood double inversion recovery if there is a benefit of a bright fat signal. This is run as a separate sequence available in most CMR scanner sequence libraries where blood pool and myocardium signal are nulled while fat remains bright.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Perform the first-pass arterial perfusion module1,2,3,11,12.
	<ol>
		<li>Obtain T1-weighted fat-saturated volumetric contrast-enhanced images; the axial plane is often most universal for mass visualization.
		<ol>
			<li>Begin imaging during contrast administration of 0.05&#8211;0.1 mmol/kg injected at 3&#8211;4 mL/s.</li>
			<li>Image until the contrast passes through the LV myocardium (40&#8211;50 heart beats). 
			NOTE: A vascular tumor enhances during perfusion sequences while a thrombus does not enhance.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Perform the post gadolinium delayed viability module1,2,3,11,12.
	<ol>
		<li>Obtain phase sensitive inversion recovery (PSIR), (~10 min post injection) 6&#8211;8 mm slices with inversion time set to null thrombus, to differentiate the thrombus from the tumor or delineate the thrombus surrounding or associated with the tumor.
		<ol>
			<li>Set the scan &#8220;time to inversion&#8221; (TI time) which changes in real time based on gadolinium kinetics and is typically set at 200&#8211;450 ms at 1.5 T; 300&#8211;550 ms at 3 T. Set a new TI time into the scanner for each PSIR sequence run, which is usually higher than the previous time based on gadolinium kinetics. 
			NOTE: Serial imaging can be performed to distinguish hypo-perfused tumor necrotic core from thrombus. This is performed by repeating the PSIR sequence at multiple time points to evaluate gadolinium kinetics with the region of concern.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Consider obtaining emerging sequences13,14,15,16,17,18,19.
	<ol>
		<li>Obtain native T1 mapping (multiple protocols available). 
		NOTE: For example, use a single shot inversion recovery readout with a 5(3)3 scheme: inversion followed by 5 acquisition heartbeats, 3 recovery heartbeats, an additional inversion followed by 3 heartbeats.</li>
		<li>Obtain post contrast T1 mapping (extracellular volume fraction). 
		NOTE: Post contrast Extracellular volume (ECV) represents a gadolinium-based measurement of the size of the extracellular space which primarily reflects interstitial disease. ECV is calculated by comparing the changes in relaxivity of myocardium and blood pool prior to and following the administration of the IV contrast agent. Serum hematocrit is necessary to calculate ECV.</li>
		<li>Obtain T2 mapping. 
		NOTE: T2 mapping can be derived from bright-blood T2 prepped SSFP sequence. Accurate application of T2 mapping requires a reference range for normal T2w signal; however, large interpatient variability of myocardial T2 signal can affect interpretation of results.</li>
		<li>Obtain a cardiac triggered 3D spoiled gradient echo acquisition named 3D-QALAS (3D quantification). 
		NOTE: This sequence uses an interleaved look-locker acquisition sequence with T2-preparation and has been shown to be a feasible option for myocardial T1 and T2 mapping in a single breath hold.</li>
	</ol>
	</li>
</ol>
3. Analysis of the MRI data
<ol>
	<li>Perform post-processing2,20.
	<ol>
		<li>Use an FDA-approved software for processing data either as part of the MRI system or on a separate workstation. 
		NOTE: Post-processing is performed or supervised by the cardiac MRI physician and appropriately documented in the report.</li>
	</ol>
	</li>
	<li>Assess ventricular chambers.
	<ol>
		<li>Perform visual analysis of global and segmental function and wall motion. Look for any wall motion abnormalities in all obtained planes.</li>
		<li>Perform quantitative analysis of ventricular volumes and wall thicknesses. Ensure there is no abnormal thickening (&#62;13 mm) or thinning of the left ventricular myocardium, which could suggest underlying pathology.</li>
	</ol>
	</li>
	<li>Evaluate T2-weighted imaging.
	<ol>
		<li>Visually analyze to detect or exclude regions of increased myocardial signal intensity indicating edema. For cardiac thrombus evaluation, the thrombus can have increased T2w signal intensity in the subacute time period and low T2w signal intensity in the chronic time period.</li>
		<li>Perform semi-quantitative analysis of T2 signal intensity ratios, if needed. Using Picture Archiving and Communication Software (PACS), draw an ROI over a portion of the LV myocardium and compare the LV T2 signal to skeletal muscle ROI signal. This can be useful in ruling out myocarditis.</li>
	</ol>
	</li>
	<li>Evaluate perfusion imaging.
	<ol>
		<li>Perform visual analysis to identify regions of relative hypoperfusion. In cardiac thrombus evaluation, the mass in question is carefully analyzed for any internal post contrast increased signal, which would suggest against thrombus and signify the presence of vascular tumor.</li>
	</ol>
	</li>
	<li>Evaluate late gadolinium enhancement (LGE) imaging within myocardium and any suspected masses.
	<ol>
		<li>Perform visual analysis to assess for the presence and the pattern of LGE. No solid regions of internal LGE are expected within a thrombus. However, a thin linear component of LGE can be seen along the outer margin of thrombus.</li>
		<li>Perform visual analysis of location and extent of LGE.</li>
		<li>Perform quantitative analysis with T1 mapping. Post processing software is used. Motion corrected sequences are used for analysis. Draw a region of interest over the mass of interest and over the myocardial regions of concern and record the pertinent T1 relaxation times. 
		NOTE: This is potentially helpful in distinguishing a thrombus from a tumor by providing quantitative assessment of pre-contrast T1 relaxation times.</li>
	</ol>
	</li>
	<li>Generate the report20,21.
	<ol>
		<li>Include general study information.
		<ol>
			<li>Document the study site, scanner information including the manufacturer and the model, the field strength, and the software platform.</li>
			<li>Document patient demographics.</li>
			<li>Document the patient ID, gender, and date of birth.</li>
			<li>Document the referring physician and service.</li>
		</ol>
		</li>
		<li>Include study performance information.
		<ol>
			<li>Document the date and time of examination, the personnel involved, the indication for examination, and the list of sequences used.</li>
			<li>Document the patient history and risk factors.</li>
			<li>Document the height, the weight, the heart rate, and the electrocardiogram interpretation.</li>
			<li>Document the contrast agent administered, the route, and the dose.</li>
			<li>Document the amount, the type, the route, and the dose of sedation, if applicable.</li>
		</ol>
		</li>
		<li>Report the cardiovascular imaging features.
		<ol>
			<li>Describe the cardiac size and function based on qualitative and quantitative assessment.
			<ol>
				<li>Report the cardiac mass and describe the location, the anatomic relationships, the 3-dimensional size, and the morphology.</li>
				<li>Report the mass T1- and T2-weighted signal characteristics of the mass. Classically, a thrombus will have low T1 and T2 signals. However, the T2w signal can vary with the age of blood products.</li>
				<li>Report the first pass perfusion pattern of the mass. The thrombus should have no internal perfusion.</li>
				<li>Report the late gadolinium enhancement pattern of the mass. Thrombus generally has no internal LGE but may have thin linear LGE signal around the periphery.</li>
				<li>Report the mass motion on cine imaging and its effect on myocardial contractility.</li>
				<li>Provide concluding statements synthesizing the findings into a comprehensive impression</li>
			</ol>
			</li>
		</ol>
		</li>
	</ol>
	</li>
</ol>

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G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiac+magnetic+resonance+imaging+in+oncology.">Cardiac magnetic resonance imaging in oncology.</a> Cancer Control. 24 (2), 147-160 (2017).</li><li>Goyal, P., Weinsaft, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiovascular+magnetic+resonance+imaging+for+assessment+of+cardiac+thrombus.">Cardiovascular magnetic resonance imaging for assessment of cardiac thrombus.</a> Methodist DeBakey Cardiovascular Journal. 9 (3), 132 (2013).</li><li>Jeong, D., Gage, K. L., Berman, C. G., Montilla-Soler, J. 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Magnetic Resonance Imaging. 38, 13-20 (2017).</li><li>Schulz-Menger, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Standardized+image+interpretation+and+post+processing+in+cardiovascular+magnetic+resonance:+Society+for+cardiovascular+magnetic+resonance+(SCMR)+Board+of+Trustees+task+force+on+standardized+post+processing.">Standardized image interpretation and post processing in cardiovascular magnetic resonance: Society for cardiovascular magnetic resonance (SCMR) Board of Trustees task force on standardized post processing.</a> Journal of Cardiovascular Magnetic Resonance. 15 (35), 1-19 (2013).</li><li>Hundley, W. 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The authors have nothing to disclose.

With the increasing quality and frequency of diagnostic imaging, it is not uncommon to discover incidental cardiac masses when performing imaging for unrelated indications. Patients with cardiac masses are often asymptomatic, and if present, symptoms are typically nonspecific.
The diagnosis of cardiac thrombus is important not only for differentiating thrombus from benign or malignant cardiac tumors, but also for determining the need for anticoagulation and prevention of embolic events<sup cla...

Cardiac magnetic resonance (CMR) imaging is an important diagnostic modality for the evaluation of cardiovascular function and pathology. Technological advances allow for reduced acquisition time, improved spatial and temporal resolution, as well as higher quality tissue characterization. These advances are particularly useful in the evaluation of cardiac masses.
Echocardiography remains the first line imaging modality for the initial evaluation of cardiac masses, specifically with respect to mass location, morphology, and physiologic impact. However, echocardiography is limited by poor tissue characterization, a restricted field of view, and operator dependent image quality. Cardiac computed tomography (CT) is often utilized as a second-line imaging modality for assessing cardiac masses. Advantages of cardiac CT over other modalities include excellent spatial resolution and a superior ability in detecting calcifications. The main disadvantage of cardiac CT is patient exposure to ionizing radiation. Additional limitations include decreased temporal resolution and soft tissue contrast resolution. CMR is emerging as a valuable tool in the characterization of cardiac masses detected on echocardiography or CT. Compared to CT, CMR does not expose patients to ionizing radiation. In addition, CMR can be useful in treatment and surgical planning1,2.
A thrombus is the most common cardiac mass. The most common locations for cardiac thrombi are the left atrium and left atrial appendage, especially in the setting of atrial fibrillation or a dysfunctional left ventricle1,3. The diagnosis of thrombus is important for the prevention of embolic events as well as establishing the need for anticoagulation. CMR can aide in determining the acuity of a thrombus. Acute thrombus typically demonstrates intermediate T1- and T2-weighted signal intensity relative to the myocardium due to high amounts of oxygenated hemoglobin. Increased methemoglobin content in the subacute thrombus results in lower T1-weighted signal intensity and intermediate or increased T2-weighted signal intensity. With a chronic thrombus, methemoglobin and water are replaced with fibrous tissue leading to decreased T1- and T2-weighted signal intensity1,2,3.
The avascular composition gives a cardiac thrombus intrinsic tissue characteristics that can be exploited by contrast enhanced CMR, to aide in the differentiation of a thrombus from other cardiac tumors4. An organized thrombus does not enhance while true cardiac lesions enhance on post contrast imaging due to the presence of intratumoral vascularity3. Arterial perfusion imaging allows real time assessment of vascularity within a mass and is critical to differentiate a thrombus from a tumor. Perfusion within a mass can also be useful in the delineation of a bland thrombus from a tumor thrombus. Cine imaging provides advantages over other modalities that can be subject to motion artifact, and the temporal resolution provided by real time gated perfusion imaging increases sensitivity in detecting enhancement5.
T1 mapping is a MR technique that allows pre-contrast native T1 relaxation times and post-contrast extracellular volume calculation to detect pathologic alterations in tissue. By adding a quantitative dimension to CMR, T1 mapping can help differentiate various disease processes from the normal myocardium. An emerging application is the characterization of cardiac masses and delineation of masses from cardiac thrombi. Previous studies performed on a 1.5 T Aera XQ scanner have reported native T1 relaxation times of a recent thrombus (911 &#177; 177 ms) and a chronic thrombus (1,169 &#177; 107 ms)6. Other pertinent native T1 relaxation times include lipoma (278 &#177; 29 ms), calcifications (621 &#177; 218 ms), melanoma (736 ms), and normal myocardium (950 &#177; 21 ms). This data suggests that T1 mapping can add quantitative information to a non-contrast exam which in the setting of contraindication to IV gadolinium could be extremely useful6,7.
Contrast-enhanced CMR has been well validated for the detection of a left ventricular thrombus. It has been shown to provide the highest sensitivity and specificity (88% and 99%, respectively) for detection of a left ventricular thrombus compared to transthoracic (23% and 96%, respectively) and transesophageal (40% and 96%, respectively) echocardiography8. Currently, there are no large-scale studies validating the utility of CMR for assessing a thrombus in other chambers of the heart3.
Despite the many advantages of CMR over other imaging modalities for evaluating cardiac masses, there are also limitations. CMR, like cardiac CT, relies on electrocardiographic gating. This can cause artifact and image degradation in patients with significant arrhythmias. Image quality can also be degraded when scanning patients who have difficulty complying with breath hold requirements. However, faster acquisition times and respiratory gating techniques allow for quality images during free breathing. The presence of certain implanted devices is a contraindication for CMR and poses as a major disadvantage, although the number of MR compatible implantable devices is increasing1,2.
In summary, specific CMR sequences can be utilized to develop a dedicated MR imaging protocol for the evaluation of a suspected cardiac thrombus. The method presented here will provide instructions for the acquisition of CMR data for evaluation of a suspected thrombus. Pre-procedure screening, sequence selection, troubleshooting, post-processing, volumetric analysis, and report generation will be discussed.

<table border="0" cellpadding="0" cellspacing="0" style="width:1335px;" width="1334">
	<tbody>
		<tr height="40">
			<td height="40" style="height:40px;width:216px;">MRI Scanner</td>
			<td style="width:272px;">Siemens Healthcare 
			Erlangen, Germany</td>
			<td style="width:344px;">Magnetom Aera 1.5 Tesla&#160;</td>
			<td style="width:503px;">MRI scanner that will be used for the demonstration</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Post processing software&#160;</td>
			<td>Medis 
			The Netherlands</td>
			<td>Qmass software</td>
			<td>post processing software for ventricular volumetric and T1 mapping analysis</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Scanner processing software</td>
			<td>Siemens Healthcare 
			Erlangen, Germany</td>
			<td>Myomaps&#160;</td>
			<td>Scanner sequence package and post processing software</td>
		</tr>
	</tbody>
</table>

cardiac magnetic resonance for the evaluation of suspected cardiac thrombus: conventional and emerging techniques

We present the conventional cardiac magnetic resonance (CMR) protocol for evaluating a suspected thrombus and highlight emerging techniques.&#160;The appearance of a mass on certain magnetic resonance (MR) sequences can help differentiate a thrombus from competing diagnoses such as a tumor. T1 and T2 signal characteristics of a thrombus are related to the evolution of hemoglobin properties. A thrombus typically does not enhance following contrast administration, which also helps differentiation from a tumor. We also highlight the emerging role of T1 mapping in the evaluation of a thrombus, which can add another level of support in diagnosis. Prior to any CMR exam, patient screening and interviews are critical to ensure safety and to optimize patient comfort. Effective communication during the exam between the technologist and the patient promotes proper breath holding technique and higher quality images. Volumetric post processing and structured reporting are helpful to ensure that the radiologist answers the ordering services&#39; question and communicates these results effectively. Optimal pre-MR safety evaluation, CMR exam execution, and post exam processing and reporting allow for delivery of high quality radiological service in the evaluation of a suspected cardiac thrombus.

The CMR protocol designed for the evaluation and diagnosis of cardiac thrombus encompasses patient screening and preparation, data acquisition utilizing specific sequences, data post-processing, and report generation. Specific signal characteristics on given sequences can infer with high accuracy the diagnosis of a cardiac thrombus and differentiate these from the competing diagnosis of a cardiac tumor. Table 1 highlights the conventional and emerging CMR sequences that a...

Watch this Scientific Journal Video about Cardiac Magnetic Resonance for the Evaluation of Suspected Cardiac Thrombus: Conventional and Emerging Techniques at JoVE.com

Cardiac Magnetic Resonance for the Evaluation of Suspected Cardiac Thrombus: Conventional and Emerging Techniques

The goal of this article is to describe how cardiac magnetic resonance can be used for the evaluation and diagnosis of a suspected cardiac thrombus. The method presented will describe data acquisition as well as the pre-procedure and post-procedure protocol.

We present the conventional cardiac magnetic resonance (CMR) protocol for evaluating a suspected thrombus and highlight emerging techniques.&#160;The ...

cardiac-magnetic-resonance-for-evaluation-suspected-cardiac-thrombus

Universidad de Cartagena UDEC

Research

JoVE Journal

Medicine

10.1K Views.  University of South Florida. The goal of this article is to describe how cardiac magnetic resonance can be used for the evaluation and diagnosis of a suspected cardiac thrombus. The method presented will describe data acquisition as well as the pre-procedure and post-procedure protocol.

Video: Cardiac Magnetic Resonance for the Evaluation of Suspected Cardiac Thrombus: Conventional and Emerging Techniques

Remote Magnetic Navigation for Accurate, Real-time Catheter Positioning and Ablation in Cardiac Electrophysiology Procedures

New remote navigation systems have been developed to improve current limitations of conventional manually guided catheter ablation in complex cardiac substrates such as left atrial flutter. This protocol describes all the clinical and invasive interventional steps performed during a human electrophysiological study and ablation to assess the accuracy, safety and real-time navigation of the Catheter Guidance, Control and Imaging (CGCI) system. Patients who underwent ablation of a right or left atrium flutter substrate were included. Specifically, data from three left atrial flutter and two counterclockwise right atrial flutter procedures are shown in this report. One representative left atrial flutter procedure is shown in the movie. This system is based on eight coil-core electromagnets, which generate a dynamic magnetic field focused on the heart. Remote navigation by rapid changes (msec) in the magnetic field magnitude and a very flexible magnetized catheter allow real-time closed-loop integration and accurate, stable positioning and ablation of the arrhythmogenic substrate.

This report provides a detailed description of a new remote navigation system based on magnetic driven forces, which has been recently introduced as a new robotic tool for human cardiac electrophysiology procedures.

New remote navigation systems have been developed to improve current limitations of conventional manually guided catheter ablation in complex cardiac ...

Direct Pressure Monitoring Accurately Predicts Pulmonary Vein Occlusion During Cryoballoon Ablation

Cryoballoon ablation (CBA) is an established therapy for atrial fibrillation (AF). Pulmonary vein (PV) occlusion is essential for achieving antral contact and PV isolation and is typically assessed by contrast injection. We present a novel method of direct pressure monitoring for assessment of PV occlusion.
Transcatheter pressure is monitored during balloon advancement to the PV antrum. Pressure is recorded via a single pressure transducer connected to the inner lumen of the cryoballoon. Pressure curve characteristics are used to assess occlusion in conjunction with fluoroscopic or intracardiac echocardiography (ICE) guidance. PV occlusion is confirmed when loss of typical left atrial (LA) pressure waveform is observed with recordings of PA pressure characteristics (no A wave and rapid V wave upstroke). Complete pulmonary vein occlusion as assessed with this technique has been confirmed with concurrent contrast utilization during the initial testing of the technique and has been shown to be highly accurate and readily reproducible.
We evaluated the efficacy of this novel technique in 35 patients. A total of 128 veins were assessed for occlusion with the cryoballoon utilizing the pressure monitoring technique; occlusive pressure was demonstrated in 113 veins with resultant successful pulmonary vein isolation in 111 veins (98.2%). Occlusion was confirmed with subsequent contrast injection during the initial ten procedures, after which contrast utilization was rapidly reduced or eliminated given the highly accurate identification of occlusive pressure waveform with limited initial training.
Verification of PV occlusive pressure during CBA is a novel approach to assessing effective PV occlusion and it accurately predicts electrical isolation. Utilization of this method results in significant decrease in fluoroscopy time and volume of contrast.

Effective pulmonary vein isolation utilizing a cryoballoon depends on complete pulmonary vein occlusion. The point of occlusion can be effectively predicted by direct analysis of pulmonary vein pressure waveform analysis during balloon inflation using a simple and reproducible technique.

Cryoballoon  ablation (CBA) is an established therapy for atrial fibrillation (AF).  Pulmonary vein (PV) occlusion is essential for achieving antral ...

Noninvasive Assessment of Cardiac Abnormalities in Experimental Autoimmune Myocarditis by Magnetic Resonance Microscopy Imaging in the Mouse

Myocarditis is an inflammation of the myocardium, but only ~10% of those affected show clinical manifestations of the disease. To study the immune events of myocardial injuries, various mouse models of myocarditis have been widely used. This study involved experimental autoimmune myocarditis (EAM) induced with cardiac myosin heavy chain (Myhc)-&#945; 334-352 in A/J mice; the affected animals develop lymphocytic myocarditis but with no apparent clinical signs. In this model, the utility of magnetic resonance microscopy (MRM) as a non-invasive modality to determine the cardiac structural and functional changes in animals immunized with Myhc-&#945; 334-352 is shown. EAM and healthy mice were imaged using a 9.4 T (400 MHz) 89 mm vertical core bore scanner equipped with a 4 cm millipede radio-frequency imaging probe and 100 G/cm triple axis gradients. Cardiac images were acquired from anesthetized animals using a gradient-echo-based cine pulse sequence, and the animals were monitored by respiration and pulse oximetry. The analysis revealed an increase in the thickness of the ventricular wall in EAM mice, with a corresponding decrease in the interior diameter of ventricles, when compared with healthy mice. The data suggest that morphological and functional changes in the inflamed hearts can be non-invasively monitored by MRM in live animals. In conclusion, MRM offers an advantage of assessing the progression and regression of myocardial injuries in diseases caused by infectious agents, as well as response to therapies.

This study demonstrates the successful establishment of magnetic resonance microscopy imaging as a non-invasive tool to assess the cardiac abnormalities in mice affected with autoimmune myocarditis. The data indicate that the technique can be used to monitor the disease-progression in live animals.

Myocarditis is an inflammation of the myocardium, but only ~10% of those affected show clinical manifestations of the disease. To study the immune events ...

Visualization of Streptococcus pneumoniae within Cardiac Microlesions and Subsequent Cardiac Remodeling

During bacteremia Streptococcus pneumoniae can translocate across the vascular endothelium into the myocardium and form discrete bacteria-filled microscopic lesions (microlesions) that are remarkable due to the absence of infiltrating immune cells. Due to their release of cardiotoxic products, S. pneumoniae within microlesions are thought to contribute to the heart failure that is frequently observed during fulminate invasive pneumococcal disease in adults. Herein is demonstrated a protocol for experimental mouse infection that leads to reproducible cardiac microlesion formation within 30 hr. Instruction is provided on microlesion identification in hematoxylin &#38; eosin stained heart sections and the morphological distinctions between early and late microlesions are highlighted. Instruction is provided on a protocol for verification of S. pneumoniae within microlesions using antibodies against pneumococcal capsular polysaccharide and immunofluorescent microscopy. Last, a protocol for antibiotic intervention that rescues infected mice and for the detection and assessment of scar formation in the hearts of convalescent mice is provided. Together, these protocols will facilitate the investigation of the molecular mechanisms underlying pneumococcal cardiac invasion, cardiomyocyte death, cardiac remodeling as a result of exposure to S. pneumoniae, and the immune response to the pneumococci in the heart.

Visualization of Streptococcus pneumoniae within Cardiac Microlesions and Subsequent Cardiac Remodeling

Streptococcus pneumoniae forms discrete non-purulent microscopic lesions in the heart. Outlined is the protocol for a murine model of cardiac microlesion formation. Instruction is provided on microlesion visualization using microscopy, discrimination between early and late microlesions, and methods to detect cardiac remodeling in hearts of convalescent animals.

During bacteremia Streptococcus pneumoniae can translocate across the vascular endothelium into the myocardium and form discrete bacteria-filled ...

Echocardiographic and Histological Examination of Cardiac Morphology in the Mouse

An increasing number of genetically modified mouse models has become available in recent years. Moreover, the number of pharmacological studies performed in mice is high. Phenotypic characterization of these mouse models also requires the examination of cardiac function and morphology. Echocardiography and magnetic resonance imaging (MRI) are commonly used approaches to characterize cardiac function and morphology in mice. Echocardiographic and MRI equipment specialized for use in small rodents is&#160;expensive and requires a dedicated space. This protocol describes cardiac measurements in mice using a clinical echocardiographic system with a 15 MHz human vascular probe. Measurements are performed on anesthetized adult mice. At least three image sequences are recorded and analyzed for each animal in M-mode in the parasternal short-axis view. Afterwards, cardiac histological examination is performed, and cardiomyocyte diameters are determined on hematoxylin-eosin- or wheat germ agglutinin (WGA)-stained paraffin sections. Vessel density is determined morphometrically after Pecam-1 immunostaining. The protocol has been applied successfully to pharmacological studies and different genetic animal models under baseline conditions, as well as after experimental myocardial infarction by the permanent ligation of the left anterior descending coronary artery (LAD). In our experience, echocardiographic investigation is limited to anesthetized animals and is feasible in adult mice weighing at least 25 g.

Echocardiographic examination is frequently used in mice. Expensive high-resolution ultrasound devices have been developed for this purpose. This protocol describes an affordable echocardiographic procedure combined with histological morphometric analyses to determine cardiac morphology.

An increasing number of genetically modified mouse models has become available in recent years. Moreover, the number of pharmacological studies performed ...

Cardiac Magnetic Resonance Imaging at 7 Tesla

CMR at an ultra-high field (magnetic field strength B0&#160;&#8805; 7 Tesla) benefits from the signal-to-noise ratio (SNR) advantage inherent at higher magnetic field strengths and potentially provides improved signal contrast and spatial resolution. While promising results have been achieved, ultra-high field CMR is challenging due to energy deposition constraints and physical phenomena such as transmission field non-uniformities and magnetic field inhomogeneities. In addition, the magneto-hydrodynamic effect renders the synchronization of the data acquisition with the cardiac motion difficult. The challenges are currently addressed by explorations into novel magnetic resonance technology. If all impediments can be overcome, ultra-high field CMR may generate new opportunities for functional CMR, myocardial tissue characterization, microstructure imaging or metabolic imaging. Recognizing this potential, we show that multi-channel radio frequency (RF) coil technology tailored for CMR at 7 Tesla together with higher order B0 shimming and a backup signal for cardiac triggering facilitates high fidelity functional CMR. With the proposed setup, cardiac chamber quantification can be accomplished in examination times similar to those achieved at lower field strengths. To share this experience and to support the dissemination of this expertise, this work describes our setup and protocol tailored for functional CMR at 7 Tesla.

The sensitivity gain inherent to ultrahigh field magnetic resonance holds promise for high spatial resolution imaging of the heart. Here, we describe a protocol customized for functional cardiovascular magnetic resonance (CMR) at 7 Tesla using an advanced multi-channel radio-frequency coil, magnetic field shimming and a triggering concept.

CMR at an ultra-high field (magnetic field strength B0&#160;&#8805; 7 Tesla) benefits from the signal-to-noise ratio (SNR) advantage inherent at higher ...

Invasive Hemodynamic Assessment for the Right Ventricular System and Hypoxia-Induced Pulmonary Arterial Hypertension in Mice

Pulmonary arterial hypertension (PAH) is a chronic and severe cardiopulmonary disorder. Mice are a popular animal model used to mimic this disease. However, the evaluation of right ventricular pressure (RVP) and pulmonary artery pressure (PAP) remains technically challenging in mice. RVP and PAP are more difficult to measure than left ventricular pressure because of the anatomical differences between the left and right heart systems. In this paper, we describe a stable right heart hemodynamic measurement method and its validation using healthy and PAH mice. This method is based on open-chest surgery and mechanical ventilation support. It is a complicated procedure compared to closed chest procedures. While a well-trained surgeon is required for this surgery, the advantage of this procedure is that it can generate both RVP and PAP parameters at the same time, so it is a preferable procedure for the evaluation of PAH models.

Here, we present a protocol to perform an invasive hemodynamic assessment of the right ventricle and pulmonary artery in mice using an open-chest surgery approach.

Pulmonary arterial hypertension (PAH) is a chronic and severe cardiopulmonary disorder. Mice are a popular animal model used to mimic this disease. ...

Human Fetal Blood Flow Quantification with Magnetic Resonance Imaging and Motion Compensation

Magnetic resonance imaging (MRI) is an important tool for the clinical assessment of cardiovascular morphology and heart function. It is also the recognized standard-of-care for blood flow quantification based on phase contrast MRI. While such measurement of blood flow has been possible in adults for decades, methods to extend this capability to fetal blood flow have only recently been developed.
Fetal blood flow quantification in major vessels is important for monitoring fetal pathologies such as congenital heart disease (CHD) and fetal growth restriction (FGR). CHD causes alterations in the cardiac structure and vasculature that change the course of blood in the fetus. In FGR, the path of blood flow is altered through the dilation of shunts such that the oxygenated blood supply to the brain is increased. Blood flow quantification enables assessment of the severity of the fetal pathology, which in turn allows for suitable&#160;in utero&#160;patient management and planning for postnatal care.
The primary challenges of applying phase contrast MRI to the human fetus include small blood vessel size, high fetal heart rate, potential MRI data corruption due to maternal respiration, unpredictable fetal movements, and lack of conventional cardiac gating methods to synchronize data acquisition. Here, we describe recent technical developments from our lab that have enabled the quantification of fetal blood flow using phase contrast MRI, including advances in accelerated imaging, motion compensation, and cardiac gating.

Here we present a protocol for measuring fetal blood flow rapidly with MRI and retrospectively performing motion correction and cardiac gating.

Magnetic resonance imaging (MRI) is an important tool for the clinical assessment of cardiovascular morphology and heart function. It is also the ...

Development and Evaluation of 3D-Printed Cardiovascular Phantoms for Interventional Planning and Training

Catheter-based interventions are standard treatment options for cardiovascular pathologies. Therefore, patient-specific models could help training physicians&#39; wire-skills as well as improving planning of interventional procedures. The aim of this study was to develop a manufacturing process of patient-specific 3D-printed models for cardiovascular interventions.
To create a 3D-printed elastic phantom, different 3D-printing materials were compared to porcine biological tissues (i.e., aortic tissue) in terms of mechanical characteristics. A fitting material was selected based on comparative tensile tests and specific material thicknesses were defined. Anonymized contrast-enhanced CT-datasets were collected retrospectively. Patient-specific volumetric models were extracted from these datasets and subsequently 3D-printed. A pulsatile flow loop was constructed to simulate the intraluminal blood flow during interventions. Models&#39; suitability for clinical imaging was assessed by x-ray imaging, CT, 4D-MRI and (Doppler) ultrasonography. Contrast medium was used to enhance visibility in x-ray-based imaging. Different catheterization techniques were applied to evaluate the 3D-printed phantoms in physicians&#39; training as well as for pre-interventional therapy planning.
Printed models showed a high printing resolution (~30 &#181;m) and mechanical properties of the chosen material were comparable to physiological biomechanics. Physical and digital models showed high anatomical accuracy when compared to the underlying radiological dataset. Printed models were suitable for ultrasonic imaging as well as standard x-rays. Doppler ultrasonography and 4D-MRI displayed flow patterns and landmark characteristics (i.e., turbulence, wall shear stress) matching native data. In a catheter-based laboratory setting, patient-specific phantoms were easy to catheterize. Therapy planning and training of interventional procedures on challenging anatomies (e.g., congenital heart disease (CHD)) was possible.
Flexible patient-specific cardiovascular phantoms were 3D-printed, and the application of common clinical imaging techniques was possible. This new process is ideal as a training tool for catheter-based (electrophysiological) interventions and can be used in patient-specific therapy planning.

Here we present development of a mock circulation setup for multimodal therapy evaluation, pre-interventional planning, and physician-training on cardiovascular anatomies. With the application of patient-specific tomographic scans, this setup is ideal for therapeutic approaches, training, and education in individualized medicine.

Catheter-based interventions are standard treatment options for cardiovascular pathologies. Therefore, patient-specific models could help training ...

A Rodent Model of The Ross Operation: Syngeneic Pulmonary Artery Graft Implantation in A Systemic Position

The Ross operation for aortic valve disease has regained new interest due to its outstanding long-term results. Nonetheless, when employed as freestanding root replacement, the possible dilation of the pulmonary autograft and subsequent aortic regurgitation is described. Several animal models have been proposed. However, these are usually limited to ex-vivo models or in-vivo experiments with relatively expensive large animal models. In this study, we sought to establish a rodent model of pulmonary artery graft (PAG) implantation in a systemic position. A total of 39 adult Lewis rats were included. Immediately after euthanasia, the pulmonary root was harvested from a donor animal (n=17). Syngeneic recipient (n=17) and sham-operated (n=5) rats were sedated and ventilated. In the recipient group, the PAG was implanted with an end-to-end anastomosis in infra-renal abdominal aortic position. Sham-operated rats underwent only transection and re-anastomosis of the aorta. Animals were followed with serial ultrasound studies for two months and post-mortem histological analysis. The median PAG diameter in the native position was 3.20 mm (IQR=3.18-3.23). At follow-up, the median diameter of the PAG was 4.03 mm (IQR=3.74-4.13) at 1 week, 4.07 mm (IQR=3.80-4.28) at 1 month, and 4.27 mm (IQR=3.90-4.35) at 2 months (p&lt;0.01). Peak systolic velocity was 220.07 mm/s (IQR=210.43-246.41) at 1 week, 430.88 mm/s (IQR=375.28-495.56) at 1 month, and 373.68 mm/s (IQR=305.78-429.81) at 2 months (p=0.02) and did not differ from the sham-operated group at the end of the experiment (p=0.5). Histological analysis did not show any sign of endothelial thrombosis. This study showed that rodent models may allow for the evaluation of the long-term adaptation of the pulmonary root to a high-pressure system. A systemically placed syngeneic PAG implantation represents a simple and feasible platform for the development and evaluation of novel surgical techniques and drug therapies to further improve the outcomes of the Ross operation.

We demonstrate how to establish a murine model of pulmonary root implantation into the descending aorta to simulate the Ross procedure. This model enables the medium/long-term evaluation of pulmonary autograft remodeling in a systemic position, representing the basis of developing therapeutic strategies to promote its adaptation.

The Ross operation for aortic valve disease has regained new interest due to its outstanding long-term results. Nonetheless, when employed as freestanding ...