What are Genetic Cardiac Conditions
What is Sudden Death Syndrome
Dr. Andrew Krahn: Sudden death is very common. Thirty thousand Canadians die suddenly every year in Canada. One out of a thousand people every year – that’s a very common problem. Ninety percent of people, when they collapse and die, they can’t be saved or aren’t resuscitated.
There’s two main causes of sudden cardiac arrest. The first is when there’s a problem with the arteries, the plumbing in the heart. That’s coronary artery disease. The second one is when there’s a problem with the heart muscle. A technical term for that is cardiomyopathy.
About 10% of people will have a cause that’s really driven by an inherited reason or a genetic cause. Those two main causes of cardiac arrest, the first one being the arteries in the heart. We have genes that program our arteries, things like cholesterol and blood pressure.
The second one would be the genes that control or program our heart muscle cells. Many of the times, people with those genetic changes are unaware of them. Half of the time when a person collapses or dies suddenly, they’re unaware that they carry those risks factors in their genes.
Kirsten Bartels: Genes are the instructions for the building blocks of our body. They allow our bodies to grow and develop and function properly. There are two main ways in which genes can cause conditions that can predispose to sudden cardiac death.
One main way our genes that are involved in the heart’s electrical system, and these can cause fatal arrhythmias, and they’re part of conditions for example: long QT syndrome or Brugada Syndrome.
The second main way is genes that are involved in the heart muscle cells, and these can cause heart muscle diseases, which can also lead to fatal arrhythmias. And one of the most common examples is hypertrophic cardiomyopathy, where the heart muscle is thicker than expected.
Dr. Andrew Krahn: Several ways they can be recognized: the first would be a person presents and has a symptom, like a fainting spell, and then gets tested, and this comes up as a question for an explanation of their fainting spell.
Second would be that they have a heart test, and that heart test shows a clue that one of these conditions is present. The third would be when something’s happened to their family member, and the question about whether it’s inherited, or they are at risk comes up and then they’re evaluated.
The tests that are done for these conditions are really usually quite simple. The first would be tests of the heart’s wires or electrical system. The one we all know well is an EKG, just a heart tracing, or a heart monitor.
Sometimes we’ll do an exercise test and look at the signal of the heart in that circumstance. Another test would be pictures of the heart, looking at the heart muscle. The one that’s used most often is called an echocardiogram, and that’s an ultrasound of the heart. And the last test would be a genetic test. This is to look at the code that programs the wires in the heart. And that’s something as simple as a spit test or a blood test.
Treatments are typically very simple. Something like a once-a-day pill to prevent getting into trouble, things like treating a fever, avoiding certain medications that may make the condition worse, or lifestyle recommendations about exercise and activity.
Sometimes treatments for patients who have a more severe case of the disease involve more invasive things, like things called an implantable defibrillator or ICD. These are for patients where they have active, life threatening conditions that continue to recur.
If you’re looking for more information about inherited causes of sudden death, you should go see your doctor, who may connect you with a local heart specialist.
Presenter: Dr. Andrew Krahn, Cardiologist, Vancouver, BC
Local Practitioners: Cardiologist
What is Brugada Syndrome?
Brugada Syndrome is a delay in the signal in the front of the heart. When we do an EKG, we can see or record this delay, and it catches our attention because it’s unusual.
It’s something that’s seen more often in men, and it’s seen more often in Asians. You cannot really feel Brugada Syndrome, unless that EKG is associated with something that leads to a fainting spell or a seizure. The abnormal heart rhythm is what you feel, not the actual Brugada EKG.
Most patients with Brugada have no symptoms, feel well, and won’t ever have a problem. Occasionally patients with Brugada – this delayed signal – will lead to an abnormal heart rhythm. That abnormal heart rhythm can cause the person to faint, it can cause them to have a seizure, they can collapse and they can even die suddenly, most often at rest or in their sleep.
Brugada occasionally runs in families, though most of the time we don’t find other family members are affected when a person has a Brugada EKG. That leads to the ability to do genetic testing for Brugada, which is sometimes helpful.
Julie Hathaway: Most patients will have Brugada diagnosed on a simple EKG test. Sometimes, that EKG shows a clear Brugada pattern, and sometimes it shows what we call a partial Brugada pattern, which we sometimes also call a type 2 pattern.
Whenever we see a type 2 pattern, the best way we can know if that’s actually a real, clear Brugada pattern is by doing some extra testing. That extra testing is called a procainamide challenge, or a drug challenge, and it involves coming to the hospital and receiving a medication by IV, while we still track your heart rate, using an EKG, to see if we can bring out that clear Brugada pattern.
The test is quite uneventful, it doesn’t hurt, it’s just a way for us to see whether that type 2, or maybe Brugada ECG pattern is actually a clear or a real Brugada pattern. Whenever we see a clear Brugada pattern, either on a simple EKG, or following a procainamide or drug challenge test, we can offer a patient a blood test called a genetic test.
That’s a test that goes in and looks for any errors in the genetic material that may have caused that Brugada pattern to happen or show up. That genetic test becomes an important piece of information for that patient’s family members and helps in their diagnosis as well.
Dr. Andrew Krahn: There’s two kinds of treatments for Brugada. Since most patients are perfectly well, there’s a simple precaution of certain medications that they should avoid, and the treatment of things like fever, and keeping in touch with their doctor to report if they have a fainting spell or a seizure.
In the small number of people who are more troubled by Brugada, where they’ve collapsed or fainted, those people typically have aggressive treatment with something like an implantable defibrillator or ICD.
If you or someone in your family is concerned about the possibility of Brugada, please go see your doctor, who may refer you to a local heart specialist.
Local Practitioners: Cardiologist
Diagnosing and Screening Genetic Heart Conditions
everal conditions require an evaluation cardiogenetic. First, different types of cardiomyopathy, or heart muscle disorders. These include hypertrophic cardiomyopathy, some forms of familial cardiomyopathies, and arrhythmogenic right ventricular cardiomyopathy.
There are also some electric problems of the heart that require an evaluation. These include Brugada syndrome, long QT syndrome among other arrhythmic problems, and also some forms of familial sudden death. There are also some cholesterol problems that need evaluation, as well as some aortic problems.
During a consultation in cardiogenetics, you usually see different people. First, we are a group of doctors working together with different specialities. There are also genetic counsellors working with us, as well as some nurses specialize in cardiogenetics. The first part of the consultation is going through your medical history and the tests you already had, and seeing if other tests are necessary to come up with a good diagnosis.
Then, we go through your family history, which is very important in the case of cardiogenetics. This includes building a family tree or a pedigree, and we put a lot of care into finding out about early cardiac diseases in the family, as well as cases of sudden death. Then we go through the treatment, see if medications are necessary, and in some rare cases – if for example, a defibrillator would be indicated. Then, we discuss about the disease. We answer your questions and we see if some preventative measures should be done.
The last part is the family screening. We make sure we know who should be screened about the disease in the family, and how we should perform the screening. Sometimes you’ll be approached for some research projects or being part of a registry about your disease. This is always optional.
Genetic testing is a blood test specifically looking at DNA. DNA is basically the instructions to build proteins in your body, for every organ, including the heart in the case that interests us. So by doing this test, we are able to see if some genes involved in the function of the heart are affected. The genetic testing can be ordered for different reasons. It can help us with your diagnosis. It can help us sometimes to guide the treatment, but it can also help us to screen other members of the family.
In your case, if we think that genetic testing should be done, this can be performed after your visit, so the blood test can be drawn after your visit at the genetic clinic, and then this blood test gets sent to a molecular lab for analysis. This result takes about a few weeks to a few months to be available, depending on the cases.
Family screening for genetic diseases is important, mainly to prevent complications in your family members. In some diseases, knowing more early about the disease can prevent complications such as heart failure, arrhythmia, and even in some cases death. The screening of the family can be done in two ways. First, if the results of the genetic testing are positive in a patient, this can be used to screen other family members.
If we don’t have positive results to one of these tests, we can perform regular tests such as blood tests, electrocardiograms and cardiac imaging tests to see if someone is at risk or affected by the disease. If you want more information on cardiogenetics, or if you think you may be affected by one of these diseases, you should contact your doctor or your cardiologist.
Local Practitioners: Cardiologist