Echocardiography (Echo) is an ultrasound of the heart. This technique uses standard two-dimensional, three-dimensional, and Doppler ultrasound to create an image of the heart.
Figure 1: A snippet from introduction to echocardiography simulation by Labster showing the condenser tube.
The basic knowledge that students should know about the heart and ultrasound waves before starting echocardiography is that the human heart consists of 2 ventricles and 2 atria. It also has 4 valves namely the mitral and tricuspid valves, which control the flow of blood from the atria to the ventricles, and the aortic and pulmonary valves, which control the blood outflow from the ventricles.
Figure 2: Anatomy of the Heart
The cardiac cycle is the period that begins with the contraction of the atria and ends with the relaxation of the ventricles. The cardiac cycle includes all events associated with blood flow through the heart during a complete heartbeat.
As you read, keep the following points in mind:
Three reasons why this topic is inaccessible to a student
Five tactics educators can use to improve student understanding
The positive effects of a virtual laboratory
There are three reasons in particular why Echocardiography can be complicated, even for the most diligent of students.
Images can be very difficult to understand, especially 2-D, and not seeing their relevance to the real world can demoralize learning and make it difficult for students to stay motivated. Echocardiography can be very technical and user dependent
There are two main types of Echocardiography and they are:
Transthoracic: The ultrasound is performed on the patient's chest. This is very common.
Trans-esophageal: This is a more specialized procedure where the probe is passed down the patient's esophagus for a clearer view of the heart. This usually requires sedation
The Doppler effect is the change in frequency or wavelength of a wave as the source and observer move toward or away from each other. One of the many uses of the Doppler effect is to determine the speed of a moving object. When a wave is created and bounces off a moving object, the change in frequency produced by the reflection can be used to determine the speed of the moving object.
This has medical implications. Frequency shifts can be used to determine the velocity of blood flow. The resulting ultrasonic waves can rebound on the many different cells within the blood and accurately measure blood velocity in the veins and arteries. However, when a blood flow measurement is needed, for example, to calculate cardiac output, you need to multiply the velocity by the vessel's cross-sectional area to get the flow rate. The velocity is measured in cm/sec, the vessel's cross-sectional area is measured in cm2 and the flow rate is measured in cm3/sec.
With these points in mind, here are five things you can consider introducing into your Echocardiography lessons to make them more engaging, approachable, and fun for you and your students.
Lazzaro Spallanzani first demonstrated in 1794 that bats can navigate by reproducing subtle sounds, so the principles of echolocation were developed.
Figure 4: A snippet from the introduction to echocardiography simulation by Labster showing the condenser tube.
Echocardiography is widely used in cardiology as a diagnostic, management, and follow-up tool. How do the echocardiographic transducers work?
The transducer creates sound waves that bounce off your heart and back to the transducer. These waves are converted into images that are displayed on the monitor. The ultrasound gel helps ultrasound waves travel from the transducer to the skin with less reflection occurring between two different media such as air and skin.
As you can see in the image below, Doppler is angle-dependent so the cursor must be parallel to the blood flow.
Figure 5: Waves being emitted and received by a transducer
Several techniques use the Doppler principle in combination with a modified Bernoulli equation. These techniques are:
1. Color Doppler
2. Pulsed-wave Doppler
3. Continuous Doppler
4. Tissue Doppler
Note: Color Doppler is a noninvasive method of imaging blood flow through the heart by displaying flow data on two-dimensional echocardiographic images. The red and blue colors represent the direction of a given jet. Different shades from dull to bright represent differing velocities. In case of turbulence, a color mosaic is created. It can determine whether regurgitation is present or not, as well as grade the regurgitation. It can also guide the user in where to place the cursor when using continuous and pulsed Doppler.
Echocardiography views: The heart is viewed from different dimensions or windows. The 5 main/basic cardiac ultrasound views (Cardiac Windows) of the heart are:
Parasternal Long Axis
Parasternal Short Axi
Apical 4 Chamber
Inferior Vena Cava(IVC) view.
Echoes are essential in today's world for detecting pathologies that can be life-threatening. Some pathologies that require Echocardiography include:
1. Cardiac Tamponade: Fluid surrounding the heart which may impair cardiac contractility
2. Arrhythmias: Irregular heartbeat with loss of synchronous blood flow from atria to the ventricles
3. Pulmonary Embolism: Clot in the pulmonary system
4. Valvular Stenosis or regurgitation: Reduced or increased valvular mobility which may reduce flow to a chamber or increase the backward flow of blood.
5. Congenital heart disease: Heart defect from birth, might be genetic.
6. Pericarditis - inflammation of the pericardial membrane
Memory aids can be a huge help in understanding this topic, but when it comes to learning the color codes in color Doppler Echo, that's where the mnemonic BART comes in. It means
Flow away from the probe appears blue(BA) and Flow towards the probe appears red (RT)
A unique way to teach Introduction to Echocardiography is through a virtual laboratory simulation. At Labster, we’re dedicated to delivering fully interactive advanced laboratory simulations that utilize gamification elements like storytelling and scoring systems, inside an immersive and engaging 3D universe.
Check out the Labster simulation that allows students to learn about Introduction to Echocardiography simulation through active, inquiry-based learning. In the simulation, students will go on a mission to learn how to perform cardiac ultrasound using different modes and views.
Learn more about the Introduction to Echocardiography simulation here or get in touch to find out how you can start using virtual labs with your students.
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