Trick Question!

I have a trick question that I ask of newcomers to the cardiac cath lab. How many major coronary arteries does the human heart have? Are there 2, 3, or 4 arteries? This is a question not only of anatomy, but about patients. The answer is below. There are many discussions on what the major arteries are and that may be debated. I asked the questions for a good reason, which will also follow after the answer.  

Approximately 90% of the population has 3 major coronary arteries. The Good Lord gave us our left hand as a teaching implement. Your left fist is about the size of your heart. If you hold your left hand up by your chest, your left thumb would represent your right coronary artery going down the back of your heart. Your left index finger would represent your left anterior descending artery to the apex of your heart in the front of your heart. Your left middle finger would represent your circumflex artery going around the circumference of the heart.

Approximately 7% of the population has 4 major coronary arteries. Under this circumstance, if you hold your left hand up by your chest, your left thumb would represent your right coronary artery going down the back of your heart. Your left index finger would represent your left anterior descending artery to the apex of your heart in the front of your heart. Your left middle finger would represent your ramus intermedius artery and your left ring finger would represent your circumflex artery going around the circumference of the heart under this circumstance.

An unfortunate 3% of the population has only 2 major coronary arteries. Under this circumstance, if you hold your left hand up by your chest, your left thumb would represent your right coronary artery going down the back of your heart. Your left index finger would represent your left anterior descending artery to the apex of your heart in the front of your heart.  

So, how many major coronary arteries does the human heart have: 2, 3, or 4? The answer is, all of the above. Approximately 90% of the population has 3 major coronary arteries, 7% of the population has 4, and an unfortunate 3% of the population has only 2 major coronary arteries. That is how they were born!

I have been involved with cardiac catheterization since 1972. I was but a wee toddler then and had to use a stool to get up to the instrument table (this was before child labor laws). Since that time, I have seen a total of 4 patients with only one major coronary artery. This is statistically insignificant. The Good Lord made them that way. There are a lot of differences, which is the whole point of the question. Everyone is an individual. We can’t lump them into one category. We shouldn’t expect them to all have 3 major coronaries. We shouldn’t expect them to all have no allergies to drugs. We shouldn’t expect them to all have a blood pressure of 110 over 70 mmHg. We should expect that we are going to have to study each individual as such. We have to care for everyone specially, as every patient is special.

Yes, it is easier to learn things in blocks. Try to keep things simple. Pigeonhole certain facts. Set certain expectations. With biology, it is different. You must remember that normal is the mean or average of a bunch of abnormals. Take the extra time and effort to investigate and research what is different about your patient. That is what health care is about: treating each patient as an individual.  Knowing that each patient is special and treating them accordingly. Assembly line care does not appeal to me! 

The good news is, as you progress in your career, you will see many different anatomies and personalities. Just wait until you run into dextrocardia, situs inversus, situs ambiguous, or heterotaxy. Today is the beginning of the rest of your career!

Acknowledgments. We would like to thank our wonderful hand model, Janice Sinfield, RN.

*Since the writing of this article, Mr. Ritchey has retired from his position at Piedmont Medical Center.

Marshall Ritchey can be contacted at marshallritchey@hotmail.com