Purpose of Cardiac Ultrasound Examination in Cats
Cardiac ultrasound, also known as echocardiography, is indicated when there is suspicion a cat may have heart disease or when chest radiographs (X-rays) reveal an enlarged heart. This diagnostic tool allows veterinarians to visualize the size of the heart chambers and assess the function of the left side of the heart. Additionally, it helps evaluate whether the heart valves are normal or thickened.
Beyond structural assessment, echocardiography can detect excess fluid in the pericardial sac surrounding the heart and sometimes identify tumors that may be causing this fluid buildup. This makes the examination invaluable for detailed characterization of cardiac health in cats suspected of heart disease or exhibiting related clinical signs.
Technical Explanation: Echocardiography
Echocardiography is a type of ultrasound examination. All kinds of ultrasound work by sending sound waves that reflect off an object and recording the returning echoes. Special probe devices are placed on the cat's chest, which emit and receive sound waves or echoes, and the echocardiography machine converts these sound waves into images of the heart.
Performing an echocardiography examination skillfully requires specialized training and accumulated experience. Because echocardiography equipment is expensive, not all veterinary clinics have this device. Your pet may be referred to a specialist veterinarian, such as a cardiologist, radiologist, or internal medicine doctor for the examination.
Currently, there are several types of echocardiography, which can be performed sequentially. Two-dimensional (2D) echocardiography shows the motion of the heart as well as the internal chambers and outer walls of the heart. The 2D echocardiogram can detect significant (major) abnormalities and identify heart regions that require further examination.
This technique can also detect tumors, excess fluid in the pericardial sac, blood clots inside the heart, and identify arrhythmias (irregular heart rhythms). Since most echocardiography machines have built-in electrocardiogram (ECG) functionality, arrhythmias can be monitored or recorded during the echocardiography procedure.
After the 2D echocardiographic assessment of the heart, a specific area is selected for M-mode echocardiography examination. This form of ultrasound is used to measure heart chambers and assess the function of the left heart. Because M-mode can freeze the movement of the heart, it allows easier measurement of different areas. M-mode measurements must be carried out correctly, as inaccurate measurements may cause underestimation or overestimation of problems.
Doppler echocardiography uses color mapping to visualize blood flow within the heart. Doppler echocardiography is used to determine if blood flow is too fast in certain areas, such as subaortic stenosis or pulmonic valve stenosis—congenital defects that cause a narrowing of blood flow openings.
Doppler echocardiography can determine the severity of defects by measuring the velocity of blood flow through the narrowed areas. It can also detect perforations in the heart walls, such as those caused by defects between the ventricles and atria. Furthermore, Doppler can identify problems associated with heart valve leakage.
Some echocardiography machines feature three-dimensional (3D) ultrasound, which can display precise images of the heart. However, at present, 3D echocardiography is mainly used for teaching purposes.
Preparing Your Cat for an Echocardiogram
Preparation for an echocardiogram usually requires little to no special steps. While some animals may need sedatives, most do not. However, some aggressive cats can be difficult to handle when awake, and in these cases, general anesthesia or sedation might be necessary to perform the exam.
It's best not to feed your pet on the morning of the exam to avoid complications if sedation is needed. To ensure optimal contact between the echocardiogram probe and your pet's skin, the fur on both sides of the chest is typically shaved. Animals with thin fur may not require shaving, but if the fur remains untrimmed, the image quality of the echocardiogram might be insufficient for diagnosis.
During the exam, most animals are asked to lie on their side. Experienced ultrasound technicians can also perform the procedure while the animal is standing or sitting. The examination should take place in a quiet room to minimize stress for your pet.
Potential Complications of Echocardiography
Echocardiography is an extremely safe procedure, and cats generally do not experience any long-term or short-term side effects.
The only potential complications arise from the use of tranquilizers and sedatives, or from general anesthesia administered during the procedure. However, side effects from these medications are uncommon.
Follow-Up Care for Cats with Heart Disease
Follow-up care is essential for managing your cat's heart condition effectively. It may be necessary to repeat echocardiogram examinations to monitor the progression of your cat's heart disease. The frequency of these tests and other follow-up visits depends on the specific condition and severity of the heart disease.
Regular check-ups with your veterinarian or veterinary cardiologist allow timely adjustments of treatment, including medication dosages and diet changes, to help maintain your cat's quality of life. Monitoring may include repeated cardiac imaging, bloodwork, and careful observation of symptoms like breathing rate and activity level.
Because cats with heart disease can experience fluctuations in clinical signs or complications such as heart failure or blood clots, ongoing evaluation ensures early detection and intervention. Maintaining a close relationship with your veterinary care team and adhering to follow-up recommendations are critical for optimal management.
