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Back To Basics: Echo. Shobha Natarajan, MD Assistant Clinical Professor The University of Pennsylvania School of Medicine. I have no disclosures. Echocardiography in Pediatric Congenital Heart Disease.
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Back To Basics: Echo Shobha Natarajan, MD Assistant Clinical Professor The University of Pennsylvania School of Medicine
Echocardiography in Pediatric Congenital Heart Disease • Revolutionalized the diagnosis and management of patients with significant congenital heart disease • Became part of clinical practice in the 1970s • There is a constant evolution of new technologies to non-invasively evaluate anatomy, physiology, and ventricular performance • But we are going to focus on the basics…
Physics of ultrasound transducer skin • Ultrasound generates images of internal organs using reflected energy from sound waves. • The frequencies of these sound waves are higher than those audible to human ear. (>20,000Hz) • This imaging strategy is similar to sonar technology used to detect objects beneath the water’s surface. Sound waves
Creating an Ultrasound Image Some waves are scattered but others are reflected back to the transducer. The crystals convert the waves to electrical impulses. Electrical impulses produce oscillations of piezoelectric crystals within the transducer that produce sound waves. These waves are emitted into the patient. Rubber coating on the transducer and water base gel helps with the transmission. The electrical impulses are processed to find the direction, strength and timing of the reflected sound wave to create an image on the computer screen.
2D Image • Fan-like image that is narrow by the transducer and widens with deeper penetration • Fluids (blood, effusion, ascites) will scatter the sound wave with little reflection and will be black. • Air and bone have little scatter and will reflect most of the sound wave back and will be bright. These structures can create artifact and limit what we can see by echo.
Doppler Ultrasound • The Doppler effect - In 1843, while studying stars, Christian Doppler found that the change in frequency of the wave reflected by an object in motion is directly proportional to the direction and speed of motion relative to the stationary observer • Echocardiography utilizes this concept to evaluate blood flow and tissue movement: the objects in motion are red blood cells or myocardial tissue and the observer is the transducer.
Doppler Ultrasound • By calculating the frequency shift of blood flow in an artery or a across a heart valve, the ultrasound processor can determine its speed and direction. • The Doppler information is displayed as a color Doppler image or graphically.
Other Modalities Courtesy of GirishShirali, MD
Imaging Windows suprasternal subcostal parasternal apical Snider AR et al, Echocardiography in Pediatric Heart Disease, 1997
Subcostal Frontal Lai, W et al, J Am Soc Echo, 2006
Subcostal Sagittal Lai, W et al, J Am Soc Echo, 2006
Apical Views Lai, W et al, J Am Soc Echo, 2006
Cases Transthoracic Echocardiography
Ebstein’s Anomaly Displaced TV to the RVOT Atrialized RV
TOF Anterior malalignment of conal septum with PS Large VSD with aortic override
Heterotaxy Syndrome: What can go wrong? • Segmental heart abnormalities • Splenic & other visceral anomalies • Systemic & pulmonary venous anomalies • Atrioventricular alignment abnormalities • Ventriculo-arterial alignment abnormalities • Outflow tract obstruction • Right aortic arch • Rhythm abnormalties • Midline defects
TEE Indications • Diagnostic Evaluation for • Suspected heart disease and poor TTE windows • PFO during workup of stroke • Intra/extracardiac baffle (Fontan/Senning) • Vegetation, abscess • Thrombus prior cardioversion • Prosthetic valve (leaflet movement, perivalvar leaks)
TEE Indications • Perioperative Indications • Preoperative definition of cardiac anatomy and function • Intracardiac air before coming off bypass • Postoperative surgical results and function • TOF • VSD (isolated or as part of a more complex repair) • AVSD • ASD • Valve intervention • Coronary intervention
TEE Indications • TEE guided catheter interventions: • Placement of ASD or VSD occlusion device • Balloon atrial septostomy • atrial stent placement
Complications & Contraindications • Several large series report 1-3% complication rate in children. • Mostly trauma, horseness, dysphagia • Reports of: • neonatal esophageal perforations. • respiratory compromise • pulmonary vein confluence obstruction • Dao obstruction
TEE in the OR Courtesy of Meryl Cohen, MD