Dr. Graham Wong, MD, MPH, FRCPC, FACC, Acute Cardiac Care, Cardiologist, talks about what a holter monitor is and how it can help diagnose cardiac conditions in a patient.

Dr. Graham Wong, MD, MPH, FRCPC, FACC, Acute Cardiac Care, Cardiologist, talks what a stress test is and how it can help diagnose cardiac conditions.

Dr. Graham Wong, MD, MPH, FRCPC, FACC, Acute Cardiac Care, discusses what an echo cardiogram is used for when diagnosing certain cardiac conditions.

A Holter monitor is a rhythm test, in which we are trying to understand the rhythms of the heart over a 24-hour monitoring period. A Holter monitor is worn by an individual, and the Holter monitor consists of a battery pack, a little computer with a little hard drive, as well as electrode leads that the patient has to put on themselves.

The Holter monitor is only effective if the leads are actually worn. After a 24-hour period, all of the heartbeats that are generated by the patient wearing the Holter monitor are captured inside the head unit of the Holter monitor. And when it’s returned to the institution that the Holter monitor was picked up from, the information is downloaded and then interpreted.

What a Holter monitor will give you is all of the heartbeats that were generated from the person over that period of time, and we can get a sense of the range of the heartbeats, what the average heartbeat was and if there are any extra heartbeats—whether they are coming from the upper or lower chamber of the heart.

This test is used when there is a suspicion of the electrical sub-system of the heart that may cause rhythm problems; either rhythm problems that generate overly quick heart rhythms, or tachyarrhythmias, or overly slow rhythms such as bradyarrhythmias. And so these would be useful in patients who complain of palpitations or other symptoms which would suggest that there are abnormalities with the rhythm of the heart.

If you have any symptoms that are worrisome for a rhythm abnormality, you may want to speak to your family physician to see if a Holter monitor is something that would be useful in trying to figure out what your symptoms are due to.

Presenter: Dr. Graham Wong, Cardiologist, Vancouver, BC

Local Practitioners: Cardiologist

A stress test is one of the most commonly used cardiovascular diagnostic tests. There are many reasons why people would reach for a stress test, and why a stress test is useful. At its heart, a stress test is an assessment of someone’s physiological or aerobic reserve, and a fairly good assessment of a person’s hemodynamic and circulatory response to exercise.

Using this test we can assess someone’s fitness level, and whether or not there are any limiting sub-systems in the heart—whether it’s the electrical system or the arterial system that might limit someone’s ability to exercise.

On a treadmill examination, where you’re able to accurately assess one’s blood pressure, one’s heart rate, and in this way we can understand your blood pressure and heart rate response to exercise, and we can very objectively assess how much aerobic work you’re performing with a series of very graded algorithms.

The most common algorithm that’s used on a treadmill is something called the BRUCE protocol. At its heart, a treadmill examination is an electrical test that looks at changes in an electrical signal—the electric cardiogram, and to determine if there are any changes that would reflect problems with the electrical sub-system, or more commonly, indirect signs that can suggest there’s something wrong with the circulatory system.

Please note that the treadmill examination is limited to our ability to look at the electrical sub-system of the heart as well as the onset of any clinical symptoms that might be reproduced with exercise, such as chest pain or shortness of breath. Although a treadmill test is—at its very nature—an electrical test, the most commonly-used reason for a treadmill is to sort of infer the health of the circulatory system, to look for problems with plugged arteries or atherosclerosis.

But please note that the treadmill examination actually does not allow us to look at the arteries themselves, what we are trying to do is infer a problem with the arteries, if there are abnormalities in the treadmill test, by looking at changes in the ECG with exercise, that may come about as a result of impaired blood flow from a blocked artery.

Because of this limitation, treadmill examinations can be wrong, and there is up to a one-third chance of what we call a false positive, and so what people need to understand that not everyone should get a treadmill examination, and that the selection of patients for treadmill examination is very important, in order to make sure that the answers that we get and the accuracy of the treadmill is as good as we can make it.

Another less common, but very important indication for using the treadmill examination would be to understand the hemodynamic response of patients with valve problems, to understand whether or not the valve has degraded or deteriorated to the point where it impairs aerobic function and physiological function, and that would give some evidence potentially that a patient is at the point where a valve needs to be replaced.

So if you have any further questions about treadmill testing, I would invite you to speak to your family physician, or your specialist who performs treadmills.

Presenter: Dr. Graham Wong, Cardiologist, Vancouver, BC

Local Practitioners: Cardiologist

An echocardiogram is an ultrasound that is performed on the heart. It is the same technology as an ultrasound that is used, for example, for pregnancy. Except instead of obviously looking at the uterus, we’re looking at the heart.

And the purpose of an ultrasound of the heart is to understand the structures, as well as the function of the heart in terms of its pumping function, its relaxation properties, as well as how well the one-way valves work. We can also get other information such as indirect assessment of pressures inside the chambers of the heart, as well as an understanding of the sac that lines the heart.

The idea of an echocardiogram is it gives us a good understanding of the net effect of all the sub-systems of the heart, on how the heart performs. Well, an echocardiogram is a fairly commonly-used test for cardiologists and for internists, and it is used when there is some question about whether or not someone has an abnormal function of either the cardiac performance, or an abnormal function in one of the valves.

Common conditions in which an echocardiogram is used to diagnose are conditions in which you’re suspicious that a patient has a weak heart, or if a patient has dysfunction of one of the valves, and you’re considering surgery or some other method to replace or repair that valve. These would be cases in which valves don’t open properly, because of end-stage changes that cause arthritic changes, or conditions which lead to incompetence of the valve, causing regurgitation.

Echocardiograms should be done in an accredited facility. Mostly they are done in hospitals, but they are private facilities. But ensure that they’re accredited, and they should be overseen by physicians who have special accreditation and/or training in echocardiography.

If you have any further questions about an echocardiogram, you should speak to your family physician, or potentially even a specialist who performs echocardiography.

Presenter: Dr. Graham Wong, Cardiologist, Vancouver, BC

Local Practitioners: Cardiologist