So the risk factors for a heart attack are the same as for a stroke? Why are heart attacks more common (or are they?)?
Yes, indeed, there is considerable overlap between stroke risk factors and heart attack risk factors:
- high blood pressure
- high cholesterol
- diabetes
- smoking
I should point out that about 1 in 8 or so strokes are NOT due to blockages in the arteries giving blood to the brain. Rather, they are due to a burst blood vessel within the brain, i.e. intracerebral hemorrhage. There is no corresponding phenomenon in the heart.
Lastly, a major risk factor for strokes is the condition called atrial fibrillation. People with atrial fibrillation can have a risk of stoke as high as 20 percent per year.
While I had been on blood pressure medication for several years, I never knew I had a heart attack until an EKG was performed (as part of a job physical for a job I really needed) and the doctor who oversaw the clinic called me two days later and asked me when I had my heart attack.
Needless to say I was like what heart attack. I went in shortly thereafter to have a nuclear stress test done and then went in a week later for an angiogram and ended up having double bypass surgery the very next day. That was 7 years ago.
I’ll add that the liver has amazing regererative capability, where the heart and brain do not.
Also, A Fib is often caused by a heart attack.
One reason people think heart attacks are more common than strokes, in my opinion, is that heart attacks have had more agressive treatments available for a longer period of time than strokes. Also drug companies have focused on heart attack pervention with various drugs, so more press.
Yeah, I saw that in my late father. He’d had two successful bypass operations, but toward the end we saw his mental function deteriorate significantly and we guessed that he had some blood flow decrease there. But he also apparently had awful circulation in his legs. Combining the two, the gangrene on his feet had progressed quite far before it was brought to anyone’s attention. I don’t know how a person could have parts of his feet turning black without deciding he needed to consult a doctor about that. (He was a widower, so ordinarily nobody saw his bare feet.) And let me tell you, it was disgusting to see. He had to have portions of his feet amputated right away, but the legs were not getting enough circulation either, and things just went from bad to worse. In those last few months it became apparent that blood just wasn’t flowing well anywhere.
As someone else has already responded, other parts of the body are also susceptible to blockages of their blood supply resulting in no oxygen reaching a given portion of that tissue or organ, resulting in turn in death of those cells if this blockage is not relieved in a short time.
Most areas of the body have overlapping arterial supply or collateral vessels that (if one artery is blocked) there is another route for oxygenated blood to get to that area. Organs like the heart, brain, kidney etc are organs where either
(1) only one artery supplies that organ so if that artery gets blocked , short of undoing the block quickly there’s no other way to get oxygenated blood to that organ OR
(2) there are a few arteries supplying that organ, but each artery covers separate portions of that organ, so that when one artery is blocked, a significant portion of that organ will be starved of oxygen. This is why they are more vulnerable to infarcts.
In the case of the heart, there are typically 2 arteries supplying oxygen to the heart muscle: the left and right coronary arteries, that both feed directly off of the aorta. While there is some overlap, large parts of the heart are typically only supplied by one or the other artery.
To quote from my old anatomy textbook: “Although there is a rich anastomosis between arterioles, this supply is inadequate to supply the requirements of cardiac muscle when there is a sudden blockage of a major branch. As a result, the region supplied by the blocked branch becomes infarcted (i.e. rendered virtually bloodless) and soon undergoes necrosis (i.e., dies).”
Some people only have one coronary artery, so you can imagine what that means for their risks if that vessel spasms or blocks off.
Wow! Do you have a cite for that?
Vascular patients always scare me.
All the diabetic feet (people with diabetes are prone to getting ulcers and gangrene in their feel abecause of poor blood supply) tended to put me off my breakfast.
Calf claudication is a symptom that is easily overlooked, one lady had no other symptoms suggestive of cardiac or atherosclerotic disease, and a normal ECG. Her problem was that the claudication in her legs gave her such severe pain that she had to sleep in a chair, and then only for 2 or 3 hours at a time. She ended up with a bilateral femoral-popliteal bypass, which is a major surgical procedure.
What always bothers me is the heavy smokers and drinkers who don’t even give up after an MI. Most people are terrified into sorting their lifestyle out a bit…some people aren’t, and they worry me.
Not for the actual risk estimate, but here’s a pretty dense E-Medicine article on the topic of coronary artery anomalies.
I suppose the smallest possible heart attack would be one where the heart muscle is deprived of oxygen for enough time to kill one cell of heart muscle. Not all heart attcks cause enormous damage to the heart, but of course, many do. Many people still die from heart attacks.
MIs or Acute cornonary syndrome can be a difficult diagnosis to make. Stories and pains can be very atypical (and I have seen MIs present as an itchy throat or without symptoms). Many people have atypical ECGs which, while not normal, do not suggest MI. Blood tests can take many hours to show evidence of MI, or show evidence without ECG changes.
Strokes can be harder to diagnose than MIs since i) symptoms are often far more subtle, ii) there is the perception less can be done for strokes than a heart attack (fewer strokes require an operation, stroke management is very time dependent, for example), iii) diagnosis depends on tests which are more expensive and harder to obtain (most ambulances could do an ECG, not many ambulances can do a CT scan).
I manage a lot of heart attacks. I get scared by the guys who (no kidding!) have been thrombolyzed four of five times but don’t take their aspirin or blood pressure medicine and keep smoking their two packs a day. I’ve seen quite a few very sick, non-compliant patients who, despite all expectations, recover from deadly illness after deadly illness and live to a ripe old age. Of course, most of these folks do not.
Cool, thanks.
I work for a medical device company that makes a lot of products to diagnose and treat atrial fibrillation. AF has a whole host of risk factors, including the typical ones for cardiovascular disease (high cholesterol, high blood pressure, etc.), but there are also congenital conditions. Additonally, people who have had some sort of heart surgery in the past are at higher risk. Just getting old is a risk factor.
What happens in AF is that the atria (the upper chambers) start beating in an uncoordinated fashion. This allows blood to pool, especially in the atrial appendages (they look a bit like ears sticking off the atria). When blood pools, it can clot, and if it clots it can break off and go someplace else (like the heart or the brain).
We have a lot of devices that are designed to measure ECGs from inside the heart. Incidentally, this is one way to estimate the size of a heart attack–you’ll get no ECG if the catheter is touching dead tissue. To try to stop AF, an electrophysiogist will go and try to burn away the part of myocardium (muscle cell) that’s causing problems.
We do both left-side and right-side work. On the left side, you have to be very careful that your device is nonthrombogenic and that it doesn’t have anything that could fall off, because if that happened, the patient could get an MI or a stroke. On the right side, the blood goes into the lungs before goig to the left side, so it’s not considered as crucial. Granted, we don’t want to give the patient a massive pulmonary embolism, but there’s considered to be more room for error. I know whether a device is left-side or right-side affects the regulatory path it takes.
I’ve also seen another way to estimate the size of an MI. I attended an animal study where they were using purposely infarcted pigs (they created the infarc by inflating a balloon catheter in a coronary artery for several minutes). The animals I saw were 3 months post-infarc. They were put in an MRI scanner and gadolinium contrast was injected into their blood. The vasculature in the MI was really tiny and the contrast tended to collect there, giving a big white spot on the MRI. Additionally, you could see the thinner layers of myocardium without even using contrast.