EP Lab Digest - October 2007 - (Page 16)

16 ECHO TECHNIQUES OCTOBER 2007 Echocardiography: The Preeminent Front Line Screening and Diagnostic Tool for Cardiovascular Imaging and Physiological Assessment Gregory Gilman, BS, RN, RDCS, FASE, and William H. Hansen, MMS, RDCS, FASE Rochester, Minnesota About the authors: Gregory Gilman, BS, RN, RDCS, FASE is a Senior Research Associate with Kardia Health Systems, Inc. He has over seventeen years of experience in echocardiography. He is a co-inventor of the Mayo Clinic-created Echocardiography Information Management System (EIMS) and a former Associate in Cardiovascular Diseases for Mayo Clinic. Mr. Gilman has published extensively on the subject of echocardiography and related scientific discoveries. William H. Hansen, MMS, RDCS, FASE is Chief Clinical Officer for Kardia Health Systems, Inc. He has over sixteen years of experience in echocardiography, and is a co-inventor and former manager of the Echocardiography Information Management System (EIMS) for Mayo Clinic. Mr. Hansen has published several manuscripts and abstracts in the field of Echocardiography and continues to lecture on several topics in Echocardiography. one can observe the expansion and contraction of the ventricles in concert with the opening and closing of the heart valves, which are driven by the rise and fall of pressures within the cardiac chambers. By selective interpretation of the reflected ultrasound, the speeds at which the structures move within the ultrasound beam are recreated into two- and three-dimensional images. This results in visualization of the relative slower moving tissue and valves, and non-visualization or darkening of areas of the image where blood is moving at a faster speed. In this manner, thrombus formations, changes in myocardial integrity due to myocardial infarction or disease infiltration, and delineation of non-myocardial structures such as tumors and cysts are readily discernable. With increased sophistication of the manipulation of the send/receive functionality of the ultrasound, advances in image quality, and the use of injectable nonradioactive microbubble agents, the imaging capabilities of ultrasound have dramatically advanced the ability to visualize cardiac structures and demonstrate perfusion within the myocardium. By overlaying a broad rather than focused Doppler scan across the imaging field, individually colored “packets” of information reflecting the direction and speed of motion of small areas within the field can be displayed as blood flow. This is referred to as color-flow Doppler. As blood moves through the valves, the overlaying of the color-flow Doppler on the twodimensional images enables visualization of normal flow through valves as well as the acceleration of flow as in the case of valvular abnormalities such as stenosis (narrowing of the valve) or regurgitation (leakage of the valve). Color-flow Doppler has resulted in clinically valuable advances into noninvasive calculation of the degree of valvular disease and associated abnormalities. Paralleling the advance of the ultrasound technologies related to the creation and interpretation of cardiovascular imaging has been the refinement of the instrumentation. The ability to miniaturize the footprint of the piezoelectric crystal has enabled them to be engineered into intravascular catheters small enough to be placed within coronary vessels. By providing the interventional cardiologist with direct visualization of atherosclerotic lesions, informed decisions as to the most appropriate interventional procedure can be made. Incrementally larger versions of this design may be placed into the great vessels, enabling real-time visualization of aortic pathologies.These catheters may also be placed within the heart to help guide the electophysiologist during mapping and ablation, as well as for real-time monitoring of increasingly performed non-invasive cardiac interventions such as percutaneous coronary interventions, atrial septal closure devices and valve repairs, and thoracoscopic coronary bypass grafting.11,12 The big brother of the intravascular ultrasound imaging devices is the transesophageal echo (TEE) probe.This remarkable innovation has enjoyed decades of utility in the clinical cardiology and cardiovascular surgery disciplines. The esophagus is positioned immediately adjacent to the left atrium and a significant portion of the great vessels.The antrum of the stomach is positioned adjacent to the inferior aspect of the left ventricle.This affords the cardiologist an opportunity to consistently image the heart and great vessels with remarkable clarity and avail themselves to most of the imaging technologies available by conventional echocardiography. This device has become the diagnostic imaging tool of choice for: detection of intracardiac thrombus in the setting of embolic events, preventing thromboembolic sequelae after cardioversion; delineation of structural specifics of valvular disease, enabling detailed surgical planning; assessment of cardiac function in patients whom have poor image quality by conventional echo; and peri-operative realtime dynamic monitoring of cardiac surgical interventions. Portability and configuration of the imaging platform has been a major focus of ultrasound machine development. Reduced size, improved ergonomic operation, small hand-held devices, ultrasound probes and catheters, and other special adaptations are now commonplace. Armature access of these machines for interventional labs and any EP patients will be referred for an echo exam at some point during their diagnosis. Therefore, in the same way we have done with EP Lab Digest’s “EP 101”and “ECG 101”sections,we have asked these authors to provide an overview about the specialized field of echocardiography. M Cardiovascular imaging presents as a landscape of multiple maturing technologies, developed through billions of dollars of research and decades of dedication by both industry and clinicians to create diagnostic tools capable of revealing many of the elusive characteristics of cardiovascular disease. So powerful are these tools that they have become integral in the clinician’s diagnostic armamentarium.1-7 For the uninitiated, echocardiography is the utilization of ultrasound to view cardiopulmonary and the major thoraco-abdominal vascular structures and obtain structural, hemodynamic and perfusion parameters of the heart and great vessels. Ultrasound imaging is accomplished by transmitting ultrasound through the tissues and fluids of the body. At the core of this technology is the piezoelectric crystal (crystalline material that converts sound into an electrical signal), which enables the generation, sending and reception of ultrasound waves. The term “two-dimensional imaging” refers to the computer re-creation of reflected ultrasound waves into an image with height and width dimensions, thus the reference to two dimensions. Threedimensional echo is in the early stages of clinical application and adds the third plane of depth.A computer-mediated rendition of the reflected signals produce still and moving images, and overlays of color Doppler images depict speed and direction of blood flow. Focused directional ultrasound, referred to as Doppler, enables the unique assessment of dynamic physiological characteristics and cardiovascular hemodynamics yielding a differentiation of etiologies for symptoms of heart failure.8-10 With this in mind, imagine the cardiac ultrasound exam as providing the ability to view thin “slices” (tomographic planes) of the beating heart. During the cardiac cycle, Copyright 2005-2007, Mayo Foundation for Medical Education and Research.

Table of Contents Feed for the Digital Edition of EP Lab Digest - October 2007

Finally! The New Registered Cardiac Electrophysiology Specialist (RCES) Credential: Interview with Christopher M. Nelson, RN, RCIS, FSICP ECG 101: Closing the Gap Phenomenon Contents Letter from the Editor ICD Patient Support Group: St. Peter’s Hospital Spotlight Interview: Community Healthcare System Use of Magnetic Catheter Navigation for Ablation of Focal Tachycardias Echocardiography: The Preeminent Front Line Screening and Diagnostic Tool for Cardiovascular Imaging and Physiological Assessment First Annual EP Lab Digest Salary Survey: Last Chance! Clinical Trial Update: 2007 Email Discussion Group Adopting and Implementing the AF Ablation Consensus Statement Electrophysiology in the West Summit Events Calendar The Sustained Treatment of Paroxysmal Atrial Fibrillation (STOP AF) Clinical Trial: Interview with Kevin Wheelan, MD Industry News and Products

EP Lab Digest - October 2007

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