TRANSTHORACIC ECHOCARDIOGRAPHY (TTE)
To effectively evaluate cardiac anatomy and functionality in a non-invasive way, TTE is the primary modality used. It enables both qualitative and quantitative evaluations. Tomographic imaging is revealed with two-dimensional echocardiography; however a three-dimensional application enables a comprehensive cardiac examination.
TRANSESOPHAGEAL ECHOCARDIOGRAPHY (TEE)
TEE is a valuable complimentary tool as it enables visualisation of the posterior cardiac structures. TEE also provides a superior spatial resolution and image quality in comparison to the TTE.
TEE is a more invasive method of imaging compared to TTE and therefore its used is reserved for incidents where the benefits of its use outweigh the associated risks. TTE is usually the first technique used as it provides direction for the use of TEE. It is more often performed to assess the cardiac source of an embolus, incidences of endocarditis or for patients experiencing atrial fibrillation. In fact, in the 1990s, TEE was regularly used to evaluate the origin of an embolism, endocarditis, prosthetic heart valve dysfunction, and aortic dissection or aneurysm.
The emergence of thoracic MRI and CT scanning have taken over from using TEE, however TEE is still used for diagnostic and assessment purposes as well as being used in cardiac surgical procedures. The first choice of tests for most patients is TTE, however in life threatening situations, TEE is likely to be used. TEE should be considered in the following clinical situations:
– suspected acute aortic pathology
– suspected prosthetic valve dysfunction
– suspected complications of endocarditis
– evaluation of left atrial thrombus in a patient with atrial fibrillation
– evaluation of source of embolism in a patient below 50 years
Cardiac function at rest, during pharmacologic stress, and during or immediately after dynamic exercise can be evaluated with echocardiography. Exercise or pharmacologic agents are used as stress mechanism to enable successful stress echocardiography. If areas of the left ventricle are not well visualised contrast agents may be useful in enhancing definition.
– evaluation of patients with known or suspected coronary artery disease
– assessment of myocardial viability
– evaluation of dyspnoea or possible cardiac origin
– evaluation for pulmonary hypertension
– evaluation of mitral valve disease
– evaluation of aortic stenosis
– evaluation of left ventricular outflow tract gradients, mitral regurgitation, and pulmonary hypertension in patients with hypertrophic or asymptomatic aortic stenosis
The contraindications of stress echocardiography are similar to those for conventional ECG testing. Contraindications are tachyarrhythmia’s and systemic hypertension.