Cath Lab Digest - October 2007 - (Page 15)

15 approximating 40 mmHg to preserve pulmonary perfusion.1 A PFO is a congenital cardiac lesion that can persist into adulthood and is extremely common, with a prevalence estimated at 25–30% of the general adult population.2,3 The septum primum and septum secundum fuse by age two in about 70 to 75 percent of children, with the remaining 25 to 30 percent having a PFO. This anatomy can lead to right-to-left shunting when the right atrial (RA) pressure is greater than the left atrial (LA) pressure (Figure 4). This can be demonstrated with maneuvers that increase RA pressures, such as the Valsalva maneuver, or in pathologic conditions that increase right-sided cardiac pressures. An important distinction is Eisenmenger’s syndrome. Figure 3. Apical four-chamber echocardiographic view demonstrating agitated saline bubble study where only the right-sided cardiac chambers are opacified, suggesting that the right-to-left intracardiac shunt is no longer present. Figure 4. Schematic showing how blood can flow across a PFO when the RA pressures are greater than the LA pressures. shunting and demonstrated no shunting at rest (Figure 3). Only a few bubbles could be visualized crossing into the left atrium with Valsalva maneuver. The patient is doing well six months later. Discussion This case demonstrates a hidden cause of CVA and how a PFO allows right-to-left shunting with elevated rightsided cardiac pressures, posing a significant risk for paradoxical embolism. The mechanism of stroke in this patient is postulated as follows: the acutely elevated right-sided cardiac pressures caused by the PE resulted in the patient’s PFO to open and allow for right-to-left shunting of blood. This shunting created a situation where a paradoxical embolus could occur where a venous thromboembolism could cross the intra-atrial communication and cause an arterial embolic phenomenon, i.e., an ischemic stroke. Acute PE causes increased pulmonary vascular resistance (PVR) that impedes right ventricular outflow. PVR is increased by the physical obstruction of the vascular bed with thrombus as well as vasoconstriction caused by inflammatory mediators and hypoxia. The correlation of pulmonary artery pressure (PAP) to thrombus size and/or burden is limited by the variable contribution of vasoconstriction among subjects. However, when obstruction of the vascular bed approaches 75%, the right ventricle must generate a systolic pressure in excess of 50 mmHg and a mean PAP http://www.emageon.com

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

Saints Medical Center Fibromuscular Dysplasia in Children and Adolescents Cerebral Vascular Accident Following a Pulmonary Embolism: Search for the Hidden Patent Foramen Ovale Contents Clinical Editor’s Corner Meetings Calendar CEU Education Center Radiation Tracking in the Cardiac Catheterization Lab Letter to the Editor Carotid Stenting: An update Release from Stent-jail: Beneficial Snow-Plowing? Patient Management Guidelines Searching for a Cardiovascular Position? Tips for Creating a ‘Stand-Out’ Resume Long-Term Implications of Short-Term Closure Decisions – The Evolution to Vascular Access Management and the Boomerang Catalyst System The Ten-Minute Interview with… Angie Bowles, RN, CCRN CMS Issues Final FY 2008 IPPS Rule ACVP• Membership Page Experience with a New Workhorse Guidewire Ask the Clinical Instructor: Q&A for Those New to Cath Lab A Glimpse of the Future of Clinical Education: Boston Scientific’s SimSuite Bus Visits Carnegie Institute 2007 Educational Fair Held at the Washington Hospital Center Research Update: Original Contribution Abstracts from The Journal of Invasive Cardiology What Do You Think? A Virtual Cath Lab Viewer (VCL): The Development of an Online 3D C-arm Simulator and Coronary Anatomy Viewer Clinical & Industry News Cost-Effectiveness of the Radial versus Femoral Artery Approach to Diagnostic Cardiac Catheterization

Cath Lab Digest - October 2007

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