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C12 Cardiology and Cardiac Surgery
Approach to ECGs Toronto Notes 2019 Echocardiography
Transthoracic Echocardiography (TTE)
• description:ultrasoundbeamsaredirectedacrossthechestwalltoobtainimagesoftheheart • indications
■ evaluation of chamber size, LVEF, wall motion abnormalities, myocardial ischemia and complications of MI
■ evaluation of chamber size, wall thickness, valve morphology, proximal great vessel morphology, pericardial effusion
■ evaluation of unexplained hypotension, murmurs, syncope, and congenital heart disease or other cardiac symptoms and unexplained signs on physical exam (i.e. leg edema)
Transoesophageal Echocardiography (TEE)
• description:invasiveprocedureusedtocomplementtransthoracicechocardiography
■ ultrasound probe inserted into the esophagus to allow for better resolution of the heart and
structures
■ better visualization of posterior structures, including left atrium, mitral, and aortic valves, inter-
atrial septum • indications
■ should be performed as the initial test in certain life-threatening situations, (e.g. aortic dissection) when other tests contraindicated (e.g. CT angiography in patient with renal failure)
■ most importantly is used to evaluate valvular morphology and function (particularly the aortic and mitral valve)
■ intracardiac thrombi, tumours, valvular vegetations (infective endocarditis), aortic dissection, aortic atheromas, prosthetic valve function, shunt, technically inadequate transthoracic study
■ evaluation for left atrial/left atrial appendage thrombus in a patient with atrial fibrillation/atrial flutter to facilitate clinical decision making regarding electrical cardioversion or ablation
• risks
■ serious complications are extremely rare (<1 in 5,000) ■ esophageal perforation
■ gastrointestinal bleeding
■ pharyngeal hematoma
Stress Echocardiography (SE)
• description:echocardiographyusingeitherexercise(treadmillorbicycle)orpharmacologicagents (dobutamine) as the stress mechanism
• indications
■ useful alternative to other stress imaging modalities
■ when ECG cannot be interpreted appropriately
■ intermediate pre-test probability with normal/equivocal exercise ECG
■ post-ACS when used to decide on potential efficacy of revascularization
■ to evaluate the clinical significance of valvular heart disease
■ evaluation of myocardial viability, dyspnea of possible cardiac origin, mitral valve disease,
aortic stenosis, mitral regurgitation, pulmonary hypertension, and patients with hypertrophic
cardiomyopathy (for LVOT obstruction) ■ dobutamine
◆ pharmacologic stress for patients who are physically unable to exercise; same indications as exercise stress echo
◆ low dose dobutamine stress echo can be used to assess myocardial viability and for assessing aortic stenosis with LV systolic dysfunction
• contraindications
■ contraindications to exercise testing
■ contraindications to dobutamine stress echocardiography: tachyarrhythmias and systemic
hypertension
■ AAA has been considered as a relative contraindication to exercise testing or dobutamine stress
echocardiography
Contrast Echocardiography with Agitated Saline Contrast
• description:improvesresolutionandprovidesreal-timeassessmentofintracardiacbloodflow
■ conventional agent is agitated saline (contains microbubbles of air)
■ allows visualization of right heart and intracardiac shunts, most commonly patent foramen ovale
(PFO) and intrapulmonary shunt
Contrast Echocardiography with Transpulmonary Contrast Agents
• description:newercontrastagentsarecapableofcrossingthepulmonarybedandachievingleftheart opacification following intravenous injection; these contrast agents improve visualization of endocardial borders and enhance evaluation of LV ejection fraction and wall motion abnormalities (in patients with technically inadequate echocardiograms), and intracardiac mass
• risks
■ risk of non-fatal MI and death are rare
■ ultrasound contrast agents may cause back pain, headache, urticaria, and anaphylaxis ■ should not be done in patients with intra-cardiac shunts