How Do I Perform a CT Cardiac Scan?
 

The following are guidelines of performing CT coronary angiogram

Patient preparation

a) NBM for 3 hours.
b) Patients above the age of 60 years are recommended to have a S.creatinin checked.
c) Patient is asked to carry his recent ECG and 2Dechocardiography Reports along with him for evaluation

(Patient with poor ejection fraction should receive less quantity of saline chaser and Beta-blocker to be avoided).

Use of Beta Blockers as premedication

Pulse, BP is evaluated and oral metaprolol (50mg or 100mg) is given and pulse and BP is re-evaluated periodically over the next 45minutes to 1hour.
If the heart rate does not fall below 65, an additional oral dose of 25mg to 50mg is given and provided his BP is not compromised.

Optimal heart rate is one, which is below 65 on my present available scanner (Sensation 64 Siemens)
Scan can be performed on higher heart rate only if it is regular and there is no beat-to-beat variation.

Preparation on table

Hands to be raised above head and the ECG leads are fixed.
It is important to practice breath-holding technique on table with patient, as variation in breathing can result in artifacts during acquisition.

Patient should be informed about the experience of diffuse warmth at the end of the injection.


Intravenous Injection

An Intravenous line of 20 no. gauge needle is taken preferably on the left side (SVC contamination is less).
Contrast concentration used is 350 or 370 or 400mg iodine/ml.
Normally amount of contrast used is 80ml which can be decreased to 50ml or can be increased to 100ml depending upon the body mass index.
A saline chaser of 40ml is a must for optimal utilization of contrast and for decreasing the contrast artifact from the SVC and right ventricle.
Rate of injection is 4.5 ml per second.
I use automated trigger software for starting of the scan. (A time lag of 10sec to be given, which includes automated breath holding instruction.)

A topogram is performed followed by a calcium score, which is nothing but a plain scan from the level of the carina till the base of the heart, for evaluation of calcified plaques along the coronary arteries.

Acquisition band for the coronary angiographic sequence is kept 1 cm above the carina down to the base of the heart.

After the procedure, the patient is kept under observation for 15 to 30 minutes after which he is asked to consume about 1-½ litres of plain water over next 4 hours.
Patients should avoid night dose of antihypertensive medications if prescribed ,as he has received Beta-blockers prior to scanning.

(The above guidelines are as per my practice over last four years, Different centers might have some different ways of doing a particular step as per there set up experience.).