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Overview of a clinical case on long ectopic left main coronary artery.
A thirty-five year old male recently found himself suffering with chest pain or what we call angina during physical activity and naturally enough, decided to visit his ER to then seek medical attention. After a series of tests and examinations, the attending physicians were able to localize a number of obstructions in one of the patient’s coronary arteries, which they identified as the primary causative factor for his chest pain.
Interestingly enough, however, the cause for angina was not the only thing which the medical team discovered. It turned out that our patient had a rare variant anatomy concerning one of his coronary arteries. Are you interested to find out more? Well, I hope so, and why not stay with me now as we explore real life case of long ectopic left main coronary artery.
Let’s begin as always by first discussing the background history and physical exam of our patient. Our case today concerns a 35-year-old diabetic and hypertensive male, who presented with stress-induced angina pectoris prior to admission. He was five feet tall and weighed a hundred and fifteen pounds. His vitals were stable and a cardiovascular system examination found nothing remarkable. When examined by ECG, no obvious signs of myocardial ischemia or infarction were observed by the attending physician. His treadmill test was strongly positive, however, for a diagnosis of stress-induced myocardial ischemia. Echocardiography revealed normal left ventricular systolic function with an ejection fraction of sixty percent and an insignificant mitral valve regurgitation.
A coronary angiography was then performed on the patient via the right radial artery route. During this procedure, the cardiologist probed for the left coronary artery from its typical origin from the ostium in the left aortic sinus but were unable to visualize it. After some exploring, they manage to selectively cannulate the left coronary artery from the right aortic sinus and shown to branch into the anterior interventricular artery – also known as the left anterior descending artery – and the circumflex artery. This confirmed that this patient had a known but rare variant of the origin of his left coronary artery known as then long ectopic left coronary artery. The angiogram also revealed critical stenosis or narrowings in the left circumflex artery, which were believed to be responsible for his angina.
The right coronary artery was visualized in its normal path and to be dominant in this patient. Our patient was later discharged from the emergency room, however, subsequent to his initial examination, he returned to the hospital a few days later to see a specialist cardiologist for further examination. This time, he underwent a CT angiogram to better show the anomalous origin of the LCA from the right sinus that was seen on radiographic angiography.
A 3D reconstruction of LCA based on his CT revealed that the left coronary artery traveled superiorly after its origin and then underwent a reverse U-turn before continuing anteriorly over the right ventricular outflow tract, before finally giving rise to the anterior interventricular artery and left circumflex artery.
Now, let’s pause there for just a second and take a moment to remind ourselves of the typical anatomy of the coronary arteries to help give our case more context.
The heart receives its arterial blood supply from two main arteries known as the right and left coronary arteries. These both branch off at the first part of the ascending aorta from their corresponding aortic sinus.
Let’s add here the superior view of the heart. The right coronary artery branches off here at the right aortic sinus and supplies the right atrium and ventricle and often, the posterior septum and inferoposterior portion of the left ventricle. The left coronary artery, however, normally arises from the left aortic sinus, and has a diameter ranging from three to six millimeters and a length of approximately from ten to fifteen millimeters. It supplies the cardiac muscle of the left atrium and ventricle as well as the anterior septum.
In our patient, however, the artery’s length was close to sixty millimeters due to the fact that it arouse off the right side of the aortic sinus before proceeding across to the left side of the heart. The clinical significance of this especially long left coronary artery is that its excessive length has to be considered for any interventional procedures proposed for this patient such as balloon angiography and placement of a stent to alleviate the patient’s exertional angina.
The arising of the left coronary artery from the right aortic sinus is a rare congenital coronary anomaly, and this anomaly may be either benign or serious depending especially on the anatomical relationship of the anomalous left coronary artery with the aorta and the pulmonary trunk. Fortunately, this particular patient’s anomalous left coronary artery had a pre-pulmonic course, coursing anterior to the pulmonary trunk.
Now, this is extremely important to take a note of as this variant is considered to be benign and not associated with sudden cardiac death. In some patients, however, the left coronary artery originates from the right aortic sinus and instead courses between the aorta and the pulmonary trunk. This variant is considered much more serious than the previous example because the pressure in the larger vessels can likely compress the left coronary artery especially during strenuous exercise. This condition is believed to be responsible for sudden cardiac death in some young athletes, and this variant of the left coronary artery usually warrants prophylactic or precautionary coronary bypass surgery.
This is an interesting case, right? And things are not always like our textbooks say they are. Human anatomy is a lot more variable than you think, so it’s always good to explore these anomalies and also what impact they have from a clinical perspective. And before we conclude this tutorial, I would like to take a few moments to explore some of the terms, procedures, and concepts mentioned in our clinical case.
Our patient was diagnosed with exertional angina pectoris on admission to ER, but what exactly does that mean?
Well, angina pectoris or sometimes referred to as simply angina is the perception of chest pain, pressure and squeezing sensation of the heart. It is most often associated with insufficient blood flow to the myocardium which to you and me is the muscle of the heart due to partial blockage or spasm in the coronary arteries. Interestingly enough, though, there is a poor relationship between the severity of pain and the degree of oxygen deprivation in the myocardium, meaning that there can be severe pain with little or no risk of myocardial infarction. And, contrastingly, you can experience an infarction with little or no prior angina pain.
Exertional angina pectoris is also referred to as stable angina because it only occurs when the heart is subject to stress as occurs during physical activity – in some cases, even mild walking. And when the patient rests, the pain resides. In a myocardial infarction, blood flow to a region of the myocardium is fully occluded and that specific area of the heart muscle undergoes death and degeneration. Resulting mortality or morbidity depends on the size of the area affected and length of time the area is deprived of oxygen.
You’ll remember from our clinical case that our patient underwent a procedure known as coronary angiogram. Now, let’s take a moment to find out more about what this entails.
Coronary angiography is a radiographic procedure that uses contrast material to detect blockages in the coronary arteries that are caused by build of plaque along the artery walls, and this procedure is often done after chest pain, sudden cardiac arrest and abnormal EKG or an exercise treadmill test. For this procedure, a catheter is threaded through an artery typically the femoral or radial artery. If you remember in the case described here, it was done through the radial artery. Using fluoroscopy, the catheter is manipulated until it is in position at one of the ostia of the aortic sinus, and once there, the contrast material is injected through the catheter so the blockages to blood flow are highlighted producing an image like this. If blockages are found, percutaneous coronary intervention such as coronary angioplasty and stent placement may be used to increase blood flow to the affected area of the heart. Or if the blockage is severe, coronary bypass procedures may be surgically implemented.
From his patient history, we were informed that our patient underwent a treadmill test, which suggested a diagnosis of stress-induced myocardial ischemia. You might be asking now, but what exactly is a treadmill test? A cardiac stress or treadmill test is an examination where the patient is asked to walk or run while on a treadmill during which his cardiac signs and symptoms are monitored for any indication of coronary artery disease. Although a cardiac stress test may suggest coronary artery disease, it is not definitive and may suggest coronary artery disease when it does not exist or may fail to indicate coronary artery disease when the patient does have the condition. Thus although these tests are diagnostically useful, they are not a hundred percent reliable.
Our final point of interest which I would like to mention is in regards to coronary dominance. What is coronary dominance, you ask? Well, you may remember earlier in the tutorial that when our patient’s right coronary artery was described as being dominant, but dominant over what exactly?
Coronary dominance refers to whether the left coronary artery specifically its circumflex branch or the right coronary artery supplies this vessel which is the posterior interventricular artery, also known as the inferior interventricular artery or posterior descending artery. Around eighty five percent of individuals are said to right dominant; the remainder may be left dominant or co-dominant which means both the left coronary artery and right coronary artery contribute to the blood flow in this vessel.
And with that we have concluded our exploration on the case of long ectopic left coronary artery. I hope you have found it as interesting as I have, and be sure to check more content here at kenhub.com for lots more clinical cases like this one here, articles, video tutorials, quizzes and lots, lots more, and I will see you on the next video.