Sorry for spelling errors typed that on an android while walking, any clarification i can provide if needed.
In other words, briefly summarize cardiology. Got it.
So, blood enters right atrium, passes tricuspid valve, is pumped by right ventricle through pulmonary valve to lungs.
In lungs the blood loses co2 and gains oxygen for use by the body, is funneled to the pulmonary veins, into the left atria. Passes the mitral valve into left ventricle and then exits the aortic valve.
Here is ahere the story of the right coronary artery, henceforth rca begins.
When the aortic valve closes and the ventricles relax and fill with blood (diastole) oxygenated blood that can no longer flow backwards into the ventricle on account of the valve being closed is directed into the ostium, or holes of both the lca and rca.
The rca traverses down the right side of the heart, and in most patients takes a turn down the posterior (back) wall of the left vebtricle where its inferior septal arteries feed the bottom portion of the septum or wall between the left and right sides of the heart.
This is the course of the main artery, and the posterior descending artery, which is essrntially the next major "highway" it merges in to.
What this all means is that the major function of the rca is to feed the muscle of the right ventricle, the bottom half of the left ventricle, and the bottom third, or so, of the septum.
As blood travels down these highways it detours down several critical 'side streets'
First it takes a turn down the conus artery and the sa nodal artery.
These vessels are responsible for feeding the right atrium and most critically the sa node. A block in the sa nodal artery, or an acute block further upstream can be devastating as this sa node is the piece of tissue that functions as the primary pacemaker (electrical ticker if you will) of the heart. This is the first reason of many as to why heart attacks that occur on the right side are so complex and concerning.
The next major detours the blood takes would be down the right ventricular artery and the acut marginal artery, which as the name suggests aids in the supply of the right ventricle and nearby structures.
We then see the origin of the av nodal artery, which supplies the av node, which is essentially the electrical doorman of the heart. It blocks impulses coming from the atria that are too fast or inappropirate and may function as a secondary pacemaker of the heart.
Without an av node you will go into complete heart block and require the placement of a pacemaker. Without a av node or sa node you will go into an idioventricular heart rhythm, which is lethal if untreated. Yet another reason right sided infarcts are concerning.
The final reason a right sided infarct is concerning involves low pressures in the right side. The right ventricle and atria are pretty lazy compared to their left sided equivilents, and when they dont get enough blood they tend to stop working entirely.
Furthermore many drugs we give to treat heart attacks that occur on the left side such as nitrates or morphine tend to lower pressures. Pressure is critical for normal heart function.. The more you stretch a rubber band the more force it has to snap back into place. However the right side as we stated is pretty lazy and operates at a much lower pressure, when we give the standard battery of drugs to a right sided patient what happends is not only is their right side more lazy and willing to quit in the first place, but we wind up taking away the extra 'stretch' the chambers need to snap back into place and pump blood, compounding the problem.
In other words a third reason right sided infarcts can be concerning is because we're limited in terms of the options available for medicines.
Lastly, why is pain felt in the arm and anterior shoulder? Scientists are actually not 100% sure.. However the best working hypothesis is that the nerves of the heart trace back to the same ganglia.. Or 'nerve root' as the pain receptors that come from that area of the body. It is thought that during a heart attack neurotransmitters get 'mixed up' in some way causing the brain to interpret the heart attack as pain coming from that region of the body.