Hey everyone, Happy Tuesday! Today we’ll be discussing everything echocardiography (or “echo” for short)!
As mentioned yesterday, echo is a crucial tool in the management of cardiac conditions. It’s a form of imaging that uses ultrasound waves to create detailed images of the heart and nearby structures, including the aorta. While a CT scan provides a still image of structures inside the body, echo provides a real-time “video” into the chest and gives us information about the size, shape, and movement of the heart’s various structures.
What is echocardiography showing us?
Since echo is a form of ultrasonography, it uses sound waves to differentiate the tissues in the chest based on their ability to transmit sound. Echo can also measure the speed and direction of blood flow through the chambers of the heart and aorta, known as “Doppler” imaging. This is commonly used to look for problems with heart valves, such as problematic backwards flow. Since echo provides a video of the heart’s function, measurements can be taken that tell us how strongly the heart is contracting, known as “ejection fraction.” Additionally, microbubbles can be injected during echo imaging to look for a small passageway from the right side of the heart to the left.
When is echocardiography used?
Echo is useful for diagnosis, monitoring, and planning treatment of various cardiac conditions. It can be performed in both outpatient and inpatient settings, at the bedside, and in the operating room. Echo is generally separated into 2 types: Transthoracic (TTE) and Transesophageal (TEE).
TTE is performed most commonly, where the ultrasound device is placed on the chest wall and images are taken through the chest. This is simple, non-invasive, and usually provides a satisfactory image.
TEE requires the use of a special probe that is inserted into the patients mouth, through their throat, and eventually goes as deep as the stomach. This allows the device to take pictures from much closer to and behind the heart. This prevents ribs and other structures from blocking the heart and impacting the quality of the image, which is the most important advantage of TEE over TTE.
However, because the TEE device sits in the esophagus/stomach, it is more invasive than TTE. It might also require a patient to fast for several hours before the procedure is performed and requires some level of anesthesia. For this reason, it is used when TTE results are inconclusive or when more detailed imaging is needed. It is also used in the operating room during most cardiac surgery procedures since the patient is already under full anesthesia.
Echocardiography and the Aorta
In terms of the aorta, echo is mainly used to look at the function of the aortic valve, such as how much blood can flow through its opening, how leaky it is, and whether or not it is a bicuspid valve. TEE can also can be used to measure the size of the aorta, but is less accurate than a CT scan, which is why CT measurements are usually used for treatment decisions. During cardiac surgery, echo tells the doctors what part of the aorta is free of debris and safe to clamp. In the case of an aortic dissection, echo is also useful in making sure instruments are placed in the correct part of the aorta (the “true lumen”) and not in what is known as the “false lumen”. So in other words, it’s an extremely important tool that doctors use frequently in the care of patients with aortic aneurysms and dissections.
What to Expect During an Echocardiogram
Whether you undergo a TTE or TEE, the procedure is generally safe and well-tolerated. For a TTE, you'll lie on an examination table while a technician moves a device over your chest to gather all the different image angles that are needed. The procedure typically lasts about 30 to 60 minutes.
For a TEE, you’ll receive mild sedation and sometimes a numbing treatment of the throat before the device is placed. The procedure may take a bit longer, and you'll be monitored closely throughout. During cardiac surgery, it is placed after you are fully under general anesthesia but before surgery begins, and stays in place until after the heart is restarted and the heart-lung machine is no longer needed.
PHEW! That was a lot of information for one day, but I hope you learned something new about echocardiography. Thanks for tuning in to another Topic Tuesday!
-Purab
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