Robert I. Lowe

Defining Left Ventricular Apex-to-Base Twist Mechanics Computed From High-Resolution 3D Echocardiography: Validation Against Sonomicrometry

OBJECTIVES To compute left ventricular (LV) twist from 3-dimensional (3D) echocardiography. BACKGROUND LV twist is a sensitive index of cardiac performance. Conventional 2-dimensional based methods of computing LV twist are cumbersome and subject to errors. METHODS We studied 10 adult open-chest pigs. The pre-load to the heart was altered by temporary controlled occlusion of the inferior vena cava, and myocardial ischemia was produced by ligating the left anterior descending coronary artery. Full-volume 3D loops were reconstructed by stitching of pyramidal volumes acquired from 7 consecutive heart beats with electrocardiography gating on a Philips IE33 system (Philips Medical Systems, Andover, Massachusetts) at baseline and other steady states. Polar coordinate data of the 3D images were entered into an envelope detection program implemented in MatLab (The MathWorks, Inc., Natick, Massachusetts), and speckle motion was tracked using nonrigid image registration with spline-based transformation parameterization. The 3D displacement field was obtained, and rotation at apical and basal planes was computed. LV twist was derived as the net difference of apical and basal rotation. Sonomicrometry data of cardiac motion were also acquired from crystals anchored to epicardium in apical and basal planes at all states. RESULTS The 3D dense tracking slightly overestimated the LV twist, but detected changes in LV twist at different states and showed good correlation (r = 0.89) when compared with sonomicrometry-derived twist at all steady states. In open chest pigs, peak cardiac twist was increased with reduction of pre-load from inferior vena cava occlusion from 6.25 degrees +/- 1.65 degrees to 9.45 degrees +/- 1.95 degrees . With myocardial ischemia from left anterior descending coronary artery ligation, twist was decreased to 4.90 degrees +/- 0.85 degrees (r = 0.8759). CONCLUSIONS Despite lower spatiotemporal resolution of 3D echocardiography, LV twist and torsion can be computed accurately.

Spontaneous multivessel coronary intramural hematoma: an insight with OCT.

Spontaneous coronary arterial intramural hematoma is a rarely diagnosed cause of acute myocardial infarction. The underlying pathophysiology is poorly understood. A historical series of intramedial dissecting hematomas, published in 1965 ([1][1]), postulated that rupture of the vasa vasorum or

Initial clinical trial of substernal epicardial echocardiography: SEEing a new window to the postoperative heart.

BACKGROUND Postoperative echocardiography windows are often of poor quality because of intervening air spaces around the heart and great vessels. We assessed the utility of a new commercially available adult chest drainage tube that has been modified with the addition of a sterile sleeve to accommodate the introduction of a nonsterile pediatric transesophageal echocardiography (TEE) probe. The TEE probe lies in a substernal epicardial position on the postoperative heart allowing one to perform substernal epicardial echocardiography (SEE). METHODS Informed consent was obtained from 21 consecutive adult cardiac operation patients. At the completion of the operation the SEE drainage tube was inserted through the rectus muscle and into the pericardium. After chest closure, all patients underwent a full echo examination using an Acuson pediatric biplane probe in the SEE position. Views obtained and ease of insertion were judged on a 1 to 10 (worst to best) scale. RESULTS Full SEE examinations were completed in an average of 12 minutes. Ease of probe entry and manipulation was excellent (ratings of 9.3 and 9.6, respectively). The quality of the anatomic images was also excellent. Substernal epicardial echocardiography tube positioning was integral to the orientation of the images obtained. There were no complications related to the placement of the SEE tubes or TEE probes. In 4 of 21 patients (19%) the SEE methodology was used serially in the intensive care unit to accurately assess ventricular function and filling during weaning of an intraaortic balloon and inotropic agents. CONCLUSIONS Substernal epicardial echocardiography is a safe and highly effective methodology for the serial echocardiographic assessment of the postoperative heart.

Clinical application and technical challenges for intracardiac ultrasound imaging catheter based ICE imaging with EP mapping

A 9F combination intracardiac imaging and electrophysiology mapping catheter has been developed and tested to help guide diagnostic and therapeutic intracardiac electrophysiology procedures. A 7.5 MHz, 64 element, side looking phased array was used for sector scanning from the tip of the catheter. Multiple electrophysiology (EP) mapping sensors were mounted as ring electrodes just proximal to the array for electrocardiographic synchronization of ultrasound images. The catheter has been used in vivo in a porcine animal model and has demonstrated useful intracardiac echocardiographic (ICE) visualization of both cardiac tissue and electrophysiology catheters in the right atrium. The catheter performed well in high frame rate imaging, color flow imaging, and strain rate imaging of atrial and ventricular structures.

Development of an electrophysiology (EP)-enabled intracardiac ultrasound catheter integrated with NavX 3-dimensional electrofield mapping for guiding cardiac EP interventions: experimental studies.

We have developed an integrated high‐resolution intracardiac echocardiography (ICE) catheter for electrophysiology (EP) testing, which can be coregistered in 3‐dimensional space with EP testing and ablation catheters using electrofield sensing.