Acoustic Activation Imaging With Intravenous Perfluoropropane Nanodroplets Results in Selective Bioactivation of the Risk Area.

Background: Acoustically activatable perfluoropropane droplets (PD) can be formulated from commercially available microbubble preparations. Diagnostic transthoracic ultrasound frequencies have resulted in acoustic activation (AA) predominately within myocardial infarct zones (IZ).

Objective: We hypothesized that the AA area following acute coronary ischemia/reperfusion (I/R) would selectively enhance the developing scar zone, and target bioeffects specifically to this region.

Acoustic Detection of Retained Perfluoropropane Droplets Within the Developing Myocardial Infarct Zone.

Perfluoropropane droplets (PDs) cross endothelial barriers and can be acoustically activated for selective myocardial extravascular enhancement following intravenous injection (IVI). Our objective was to determine how to optimally activate extravascular PDs for transthoracic ultrasound-enhanced delineation of a developing scar zone (DSZ). Ultrafast-frame-rate microscopy was conducted to determine the effect of pulse sequence on the threshold of bubble formation from PDs.

The health effect of probiotics on high-fat diet-induced cognitive impairment, depression and anxiety: A cross-species systematic review.

Obesity is a complex disease with many co-morbidities, including impaired cognitive functions. Obese individuals often contain an aberrant microbiota. Via the microbiota-gut-brain axis, the altered microbiota composition can affect cognition or induce anxiety- or depressive-like behavior.

Influence of right ventricular pressure and volume overload on right and left ventricular diastolic function.

Background: Ventricular interdependence may account for altered ventricular mechanics in congenital heart disease. The present study aimed to identify differences in load-dependent right ventricular (RV)-left ventricular (LV) interactions in porcine models of pulmonary stenosis (PS) and pulmonary insufficiency (PI) by invasive admittance-derived hemodynamics in conjunction with noninvasive cardiovascular magnetic resonance (CMR).

Methods: Seventeen pigs were used in the study (7 with PS, 7 with PI, and 3 controls).

Efficacy of Sonothrombolysis Using Acoustically Activated Perflutren Nanodroplets versus Perflutren Microbubbles.

Nanoscale-diameter liquid droplets from commercially available microbubbles may optimize thrombus permeation and subsequent thrombus dissolution (TD). Thrombi were made using fresh porcine arterial whole blood and placed in an in vitro vascular simulation. A diagnostic ultrasound probe in contact with a tissue-mimicking phantom tested intermittent high-mechanical-index (HMI) fundamental multipulse (focused ultrasound [FUS], 1.

Delayed Echo Enhancement Imaging to Quantify Myocardial Infarct Size.

Background: Perfluoropropane droplets formulated from commercial microbubbles exhibit different acoustic characteristics than their parent microbubbles, most likely from enhanced endothelial permeability. This enhanced permeability may permit delayed echo-enhancement imaging (DEEI) similar to delayed enhancement magnetic resonance imaging (DE-MRI). We hypothesized this would allow detection and quantification of myocardial scar.

Selective infarct zone imaging with intravenous acoustically activated droplets.

Background: Microbubbles (MB) can be compressed to nanometer-sized droplets and reactivated with diagnostic ultrasound; these reactivated MB possess unique imaging characteristics.

Objective: We hypothesized that droplets formed from compressing Definity MB may be used for infarct-enhancement imaging.

Methods: Fourteen rats underwent ligation of their left anterior descending (LAD) artery, and five pigs underwent 90 minute balloon occlusions of their mid LAD.

Right ventricular energetics and power in pulmonary regurgitation vs. stenosis using four dimensional phase contrast magnetic resonance.

Objective: We investigated a full energetic profile of pressure and volume loaded right ventricle (RV) in porcine models by evaluating kinetic energy (KE), stroke power, power output and power loss across pulmonary valves with stenosis (PS) or with regurgitation (PR).

Methods: Fifteen pigs (6 PS and 6 PR, 3 unoperated controls) were studied. Phase-contrast 4D-flow MRI was performed in models of PS and PR at baseline and at 10-12 weeks, in conjunction with cardiac catheterization.

Location and structure of fibrous sheath formed after placing a tunneled hemodialysis catheter in a large pig model.

Background And Objectives: We evaluated the location and structure of the fibrous sheath formed after the placement of tunneled, cuffed hemodialysis catheters in large animals, 70 kg pigs. We focused on describing the location of the fibrous sheath in relation to the catheter. Its location explains the fibrous sheath's ability to cause catheter dysfunction by covering the catheter exit ports located at the catheter's tip.

Surgical technique of placement of an external jugular tunneled hemodialysis catheter in a large pig model.

Background: Currently, there is insufficient knowledge about the surgical anatomy and surgical techniques in large animals that can be used to test medical devices designed for human use. We encountered this problem in our study requiring the placement of jugular vein, tunneled, cuffed hemodialysis catheter in 70 kg pigs. Despite the operator's extensive expertise in placing tunneled hemodialysis catheters in humans, the important differences in anatomy made the procedure and choosing the appropriate catheter length challenging.

ULTRASOUND INDUCED MICROBUBBLE CAVITATION FOR THE TREATMENT OF CATHETERIZATION INDUCED VASOSPASM.

Inertial cavitation inducing ultrasound-mediated microbubble treatments can produce resolution of vasospasm and restoration of distal arterial flow after peripheral artery injury. Resolution of catheter-induced vasospasm is likely to be nitric oxide- mediated because improvements in stenosis diameter and downstream blood flow were blunted following pretreatment with L-NAME. The potential for clinical applicability of this therapy is significant because: 1) microbubbles can be delivered systemically into the site of injury enabling relatively high local concentration; 2) targeted transcutaneous ultrasound delivery is achievable due to the proximity of vessels; and 3) microbubbles and diagnostic ultrasound system used are commercially available.

The Thrombolytic Effect of Diagnostic Ultrasound-Induced Microbubble Cavitation in Acute Carotid Thromboembolism.

Background: Acute ischemic stroke is often due to thromboembolism forming over ruptured atherosclerotic plaque in the carotid artery (CA). The presence of intraluminal CA thrombus is associated with a high risk of thromboembolic cerebral ischemic events. The cavitation induced by diagnostic ultrasound high mechanical index (MI) impulses applied locally during a commercially available intravenous microbubble infusion has dissolved intravascular thrombi, especially when using longer pulse durations.

Diagnostic Ultrasound High Mechanical Index Impulses Restore Microvascular Flow in Peripheral Arterial Thromboembolism.

We sought to explore mechanistically how intermittent high-mechanical-index (MI) diagnostic ultrasound impulses restore microvascular flow. Thrombotic microvascular obstruction was created in the rat hindlimb muscle of 36 rats. A diagnostic transducer confirmed occlusion with low-MI imaging during an intravenous microbubble infusion.

Targeted Transthoracic Acoustic Activation of Systemically Administered Nanodroplets to Detect Myocardial Perfusion Abnormalities.

Background: Liquid core nanodroplets containing condensed gaseous fluorocarbons can be vaporized at clinically relevant acoustic energies and have been hypothesized as an alternative ultrasound contrast agent instead of gas-core agents. The potential for targeted activation and imaging of these agents was tested with droplets formulated from liquid octafluoropropane (C3) and 1:1 mixtures of C3 with liquid decafluorobutane (C3C4).

Methods And Results: In 8 pigs with recent myocardial infarction and variable degrees of reperfusion, transthoracic acoustic activation was attempted using 1.

Sheep Model of Hemodialysis Arteriovenous Fistula Using Superficial Veins.

Current models of animal arteriovenous fistula (AVF) are swine models of femoral vein terminolaterally anastomosed to femoral artery, creating a deep AVF. This feature sets it aside from human AVFs using superficial veins. Our AVF model uses sheep superficial veins to create an AVF almost identical to human model.

Utilization of modified diagnostic ultrasound and microbubbles to reduce myocardial infarct size.

Objective: We sought to determine whether guided high mechanical index (MI) impulses from a diagnostic ultrasound transducer during an intravenous microbubble infusion could augment low-dose fibrinolytic therapy in treating acute myocardial infarction (ST segment elevation myocardial infarction, STEMI).

Methods: Acute thrombotic occlusions of the left anterior descending were created in 32 atherosclerotic pigs. Fourteen historical control pigs received half dose of tissue plasminogen activator alone (half tPA), while the subsequent 18 were randomised to (a) 1.

Dosimetrically triggered adaptive intensity modulated radiation therapy for cervical cancer.

Purpose: The widespread use of intensity modulated radiation therapy (IMRT) for cervical cancer has been limited by internal target and normal tissue motion. Such motion increases the risk of underdosing the target, especially as planning margins are reduced in an effort to reduce toxicity. This study explored 2 adaptive strategies to mitigate this risk and proposes a new, automated method that minimizes replanning workload.

Improvements in cerebral blood flow and recanalization rates with transcranial diagnostic ultrasound and intravenous microbubbles after acute cerebral emboli.

Objectives: Intravenous microbubbles (MBs) and transcutaneous ultrasound have been used to recanalize intra-arterial thrombi without the use of tissue plasminogen activator. In the setting of acute ischemic stroke, it was our objective to determine whether skull attenuation would limit the ability of ultrasound alone to induce the type and level of cavitation required to dissolve thrombi and improve cerebral blood flow (CBF) in acute ischemic stroke.

Materials And Methods: In 40 pigs, bilateral internal carotid artery occlusions were created with 4-hour-old thrombi.

Improved sonothrombolysis from a modified diagnostic transducer delivering impulses containing a longer pulse duration.

Although guided high-mechanical-index (MI) impulses from a diagnostic ultrasound transducer have been used in preclinical studies to dissolve coronary arterial and microvascular thrombi in the presence of intravenously infused microbubbles, it is possible that pulse durations (PDs) longer than that used for diagnostic imaging may further improve the effectiveness of this approach. By use of an established in vitro model flow system, a total of 90 occlusive porcine arterial thrombi (thrombus age: 3-4 h) within a vascular mimicking system were randomized to 10-min treatments with two different PDs (5 and 20 μs) using a Philips S5-1 transducer (1.6-MHz center frequency) at a range of MIs (from 0.

Prevention of arteriovenous shunt occlusion using microbubble and ultrasound mediated thromboprophylaxis.

Background: Palliative shunts in congenital heart disease patients are vulnerable to thrombotic occlusion. High mechanical index (MI) impulses from a modified diagnostic ultrasound (US) transducer during a systemic microbubble (MB) infusion have been used to dissolve intravascular thrombi without anticoagulation, and we sought to determine whether this technique could be used prophylactically to reduce thrombus burden and prevent occlusion of surgically placed extracardiac shunts.

Methods And Results: Heparin-bonded ePTFE tubular vascular shunts of 4 mm×2.

Diagnostic ultrasound induced inertial cavitation to non-invasively restore coronary and microvascular flow in acute myocardial infarction.

Ultrasound induced cavitation has been explored as a method of dissolving intravascular and microvascular thrombi in acute myocardial infarction. The purpose of this study was to determine the type of cavitation required for success, and whether longer pulse duration therapeutic impulses (sustaining the duration of cavitation) could restore both microvascular and epicardial flow with this technique. Accordingly, in 36 hyperlipidemic atherosclerotic pigs, thrombotic occlusions were induced in the mid-left anterior descending artery.

Combination of real time three-dimensional echocardiography with diagnostic catheterization to derive left ventricular pressure-volume relations.

Aims: The aim of this study was to investigate the left ventricular (LV) myocardial contractility index-Emax using transesophageal real time three-dimensional echocardiography (RT3DE) combined with catheterization.

Methods: Transesophageal RT3DE (single beat, X7-2 × matrix, iE33, Philips) was used to obtain real time LV volumes in pigs. Volumes were integrated with LV pressures from conductance catheterization (CC) to create RT3DE pressure-volume relations.

Validation of admittance computed left ventricular volumes against real-time three-dimensional echocardiography in the porcine heart.

The admittance and Wei's equation is a new technique for ventricular volumetry to determine pressure-volume relations that addresses traditional conductance-related issues of parallel conductance and field correction factor. These issues with conductance have prevented researchers from obtaining real-time absolute ventricular volumes. Moreover, the time-consuming steps involved in processing conductance catheter data warrant the need for a better catheter-based technique for ventricular volumetry.