Summarize this article:

If you notice any of the above-mentioned symptoms, then get your cat checked out by a veterinarian. As part of the examination, the vet will listen to the cat's heart with a stethoscope. Based on what they find, the vet will suggest the most appropriate tests. To get an overview of how sick the cat is, the veterinarian may ask to watch the cat as it rests in a basket or box before the exam, which allows the vet to observe the cat's breathing before the stress of an exam. The vet will count the respiratory rate and assess how the cat is breathing. With a healthy cat, it is sometimes difficult to see the chest moving in and out. If the cat is having difficulty breathing, either because of heart or lung issues, the chest moves in an exaggerated in-out movement which is clear to see.  Another hint that points toward abnormal breathing is if the cat's tummy is going in and out with each breath. This is known as "abdominal breathing" and is a sign that the cat is struggling to draw air into the lungs. It's important to note that cats rarely cough as a result of heart disease, unlike dogs. Your vet will want to know if the cat has previously been diagnosed with a heart murmur. If your cat had a heart murmur, it is considered a pre-exisiting condition that could cause heart disease. Your cat may have developed a heart murmur later in life, so a clean medical history does not mean that your cat can't have an issue now. The veterinarian will listen to the cat's heart in order to assess whether a murmur is present or not and how loud the murmur is. The vet will also check the heart rhythm and rate. Heart murmurs are common in cats with heart disease. However, a heart murmur does not mean that your cat definitely has heart disease. The heart rate is an important guide as to whether the heart is struggling or not. A cat's normal heart rate is approximately 120-140 beats per minute.  A stressed cat will have a faster heart rate, meaning that the vet's measurement could be high. While a cat is at the vet, most vets consider up to around 180 beats per minute to be normal. Out of the vet's office, 180 beats is very concerning. A cat's heart may be beating fast to maintain circulation if its heart is failing. An abnormal heart rhythm is a warning signal that the heart is struggling. A healthy heart rhythm falls into one of two patterns.  First, the beat is regular with exactly the same time interval between beats. Second, the cat's heartbeat is synchronized with its breathing. An abnormal heart rhythm is erratic. A cat's gums should be a healthy pink color, just like our own. The veterinarian checks the gum color for indications of circulatory problems. If the heart is failing and the circulation poor, the gums tend to be pale or even white. However, this sign is not exclusive to heart disease and gums can be pale because of anemia or pain. The vet may do something that looks pretty odd, which is to wet the fur on the cat's neck with surgical spirit or rubbing alcohol. She does this in order to see the outline of the jugular veins which contain blood returning to the heart. These veins run up the neck, and if the heart is struggling, blood tends to accumulate downstream of the heart and cause the jugular veins to distend.

Summary:
Bring your cat to the vet for a physical exam. Expect the vet to assess your cat's breathing. Check for abnormal breathing. Inform the vet about any history of heart murmur. Allow the vet to listen for heart murmurs. Ask the vet about the cat's heart rate. Ask the vet about the cat's heart rhythm. Make sure the vet checks the cat's mucous membrane color. Observe as the vet checks the cat's jugular vein distension.