A loop recorder is a portable device that allows for the patient to record a sample strip of what the heart is doing at any particular moment in time (rhythm strip). It uses digital technology to save a sample of the heart recording from as long as 30-60 seconds prior to the activation of the device. This way, the patient can experience a temporary symptom, following which they activate the recorder, and yet the recorder is still able to record and store the heart rhythm which the patient had prior to the activation of the device even though the symptom had resolved by the time that the patient activated the device. The loop recorder is useful for assessing the presence of either fast or slow heart rhythms in patients who are complaining of symptoms of palpitations, lightheaded spells, blackouts, episodic shortness of breath, spells of tiredness, strokes, random episodes of chest pain, etc. This device is usually given to the patient for a period of 7-14 days.
A holter monitor may also allow for the recording of the patient's rhythm strip, except that in this case, the strip is a continuous recording over a 24-48 hour time period. The physician is able to view how the patient's heart beat behaves during this entire period of time including the full range of heart beat rates as well as any unique activations which the patient may create during symptomatic events. The disadvantage of this test is that the patient only wears the device for up to 48 hours. Consequently, if symptoms are occurring less frequently, then there may not be an opportunity to capture any abnormal events.
External Loop Recorder or Holter
Cardiac Catheterization (Coronary Angiogram)
A long thin flexible hollow tube called a catheter is inserted into a blood vessel in the patients arm or groin and is threaded along the vessel up to the heart. Once it is brought up to the level of the heart, iodine contrast dye may be injected directly into the blood stream (coronary artery) that is entering the heart. This contrast agent is unique and shows up easily on xray imaging. As the dye is injected, continuous xray imaging is done such that the injection of the dye may be captured in a video format. The dye fills the lumen of the coronary arteries and/or the heart chambers and therefore permits the cardiologist to see if there are any irregularities or blockages present in these arteries. This information is then used to determine whether or not the patient has significant coronary artery disease, and whether or not he should undergo angioplasty , bypass, or be best managed with medical therapy. The injection of contrast dye may also be used to look for valve leaks, for abnormal chamber size, or for congenital defects. The catheter itself allows for pressure readings from inside the heart to be taken and reviewed which has added value to the cardiologist. This test has long since been considered the gold-standard test for assessing coronary artery disease. It is considered an invasive test and has some risks which are always discussed with the patient prior to having it done.
This is a type of ultrasound test which permits the cardiologist to see moving pictures of your heart muscle and valves. Some of the things that it can be used for include the identification of the cause of an abnormal heart sound or murmur, the thickness of the heart wall, the size and shape of the different cardiac chambers, and the ability of the heart to pump blood at rest . All of these images elicit information which can then be reviewed in the context of how things are supposed to look and function for a normal healthy person. This test lasts approximately 45 minutes. When coupled with stress testing (either treadmill or pharmaceutically driven), the echo images permit the cardiologist to analyze whether or not the heart's response to exercise is normal or not. Under conditions of exercise, the heart is expected to respond a certain way, and failure to do so is often a sign of heart disease (example : coronary disease, cardiomyopathy,valvular heart disease, hypertension, pulmonary hypertension, etc).
An exercise stress test allows the cardiologist the opportunity to evaluate the patient's exercise tolerance, the behaviour of the electrocardiogram, the presence of any abnormal heart rhythms, whether or not the blood oxygen level drops (oxygen saturation), and the response of the blood pressure to a supervised stress-event.
By partnering echo images with the exercise test in a stress echo test, the cardiologist may also have the opportunity to analyze the heart's ability to respond to this period of stress, comparing the mages at rest with the images taken during exercise, specifically looking at:
the pattern of wall motion of each heart segment
the function of each of the valves
the behaviour of the lung pressures
The cardiologist expects to see a normal pattern in each case. However, in patients with heart disease, a unique pattern may be seen with each different types of heart problem. In general, when there is a heart problem present, the heart will have difficulty keeping up with the extra demand that is expected of it during this period of exercise.
2D Echo Doppler
Stress Testing and Imaging
An abnormal stress response may be seen in patients with coronary artery disease, cardiomyopathy, valvular heart disease, systemic hypertension, pulmonary hypertension, etc. Depending on how significant the abnormality is, and/or how limited the patient performs , the doctor can then determine whether or not the patient may best be managed by medical therapy or by intervention.
By partnering nuclear images with the exercise test in a stress nuclear test, the cardiologist may also have the opportunity to analyze the heart's ability to respond to this period of stress, comparing the mages at rest with the images taken during exercise, specifically looking at
the pattern of the blood flow that is coursing through the coronary arteries
The cardiologist expects to see a normal pattern in each case. However, in patients with coronary artery disease, a unique pattern may be seen.
The cardiologist will decide which of the above two stress imaging tests might be most helpful for each patient, depending on the availability of the testing, as well as the unique features of each individual patient, some of which might benefit more from one test over the other .
Cardiac MRI Scan
This is a medical technology that allows for the non-invasive assessment of cardiac structure and function. It is derived using the principles of MRI scanning but, then applied in a time-dependent approach to scan the beating heart which may allow for both static and dynamic images of the heart to be taken. The MRI scan is extremely useful in the assessment of cardiac structures (size and shape of chambers), the presence or absence of muscle scarring (as might be seen with a previous heart attack or is the case of a cardiomyopathy), assessing heart function (using motion imaging), assessing heart muscle perfusion, etc. The movie image below provides an example of the utility of cardiac MRI scanning
CT Coronary Angiogram
This is a non-invasive imaging technique that allows for the cardiologist to see the coronary arteries using CT scan technology. It is considered to be fairly accurate in defining the presence or absence of coronary artery disease. Unfortunately, it is not considered to be as accurate as coronary angiography in defining the degree of the coronary artery disease that may be present. One of its greatest utilities is in proving whether or not a patient has normal coronary arteries or not. Although it is a non-invasive test, it is still not without "risk", since patients are still exposed to a "radiation dose" during the performance of this test (just as they are with the performance of a nuclear scan or with a coronary angiogram) and patients will receive an iodine based contrast injection which may rarely cause problems.