​Clinical Procedures - Echocardiography

​Clinical Procedures - Echocardiography
Indications
• Myocardial infarction: assess wall motion and left ventricular function
• Valvular heart disease: assess competency and examine prostheses
• Embolic stroke: to exclude a cardiac embolic source
• Infective endocarditis: look for valvular vegetations
• Cardiomyopathy: assess ventricular dilatation/hypertrophy and function
• Congenital heart disease
• Pericardial disease
• Pericardial effusion: distribution of fluid and suitability for drainage
• Aortic disease: severity and site of aneurysm, dissection, or coarctation.
Contraindications
• The only contraindication is lack of patient consent or if the patient is unable to cooperate.
Technology
• Echocardiography is an ultrasound examination and uses the same technology (and machines) as general ultrasound. See separate topic
• Ultrasound becomes increasingly less diagnostic at greater depths and cannot see through lung. Images in large individuals are often suboptimal and the heart may not be seen at all in patients with hyperinflated lungs.
Procedure
• Time taken will vary depending on examinations performed and complexity of the findings. Most examinations last between 20-25 minutes
• With the patient lying on their left side, the operator uses a hand-held probe coated with gel to examine the heart usually via the anterior chest and epigastrium.
Risks
•There is no published evidence that ultrasound has ever directly caused any harm to a patient
• Heating: some equipment can produce temperature rises of 4°C in bone. Most equipment in clinical use is unlikely to increase tissue temperature more than the 1.5°C which is considered 'safe
• Non-thermal hazard: ultrasound has been demonstrated to produce tiny gas pockets and bubbles in animal models but there is no evidence that diagnostic ultrasound can cause harm to tissues other than neonatal lung.

Patient Preparation
• No preparation is required.
Other Information: Type of Echocardiography
Along with 2-dimensional transthoracic echocardiography, the following methods exist:
• 3D: uses computer software to produce a 3-dimensional image. Useful in left-ventricular functional assessment especially post-infarction
• 4D: 3D imaging with real-time movement captured
• TOE: transoesophageal echo is an invasive procedure. It requires written consent and is performed under sedation with local anaesthetic spray to the upper pharynx. The probe is covered, lubricated, and passed into the esophagus behind the heart. It is used to visualize the posterior cardiac structures. The investigation of choice for infective endocarditis
• Stress echo: used to assess myocardial ischaemia at 'rest and during
'stress'. Stress is induced by exercise or (more commonly) by an IV infusion of dobutamine in a controlled environment
• Bubble studies: used to assess for intracardiac shunts such as atrial or ventricular septal defects or patent foramen ovale. Air bubbles are agitated in a syringe and injected into a peripheral vein. The Valsalva manoeuvre is performed and, if a shunt exists, bubbles will be seen moving from the right side of the heart to the left.