 Today, we're going to discuss cardiomyopathies. First and foremost, we'll discuss a dilated cardiomyopathy. Dilated cardiomyopathies are the most common cardiomyopathies that you will see in your patients. It is characterized by cardiac enlargement with a dilation, hence where the word dilated cardiomyopathy comes from, the dilation of any of the chambers of the heart that will result in a progressive congestive heart failure. So what you're going to see with patients that have a dilated cardiomyopathy is heart failure, an S3 heart sound that comes after S2 during diastole, a systolic regurgitation murmur, a dilated heart on an echocardiogram, and you will see a balloon appearance on the chest x-ray. So over here on the right, you can see this chest x-ray where the outline of the heart is extremely large because we are dilating those ventricles and a large portion of the chest is being taken up by the heart that has become extremely large. This enlargement is characterized as the sarcomeres being added in series. We will distinguish that from a hypertrophic obstructive cardiomyopathy based upon how the sarcomeres are constructed. So with a dilated cardiomyopathy, the sarcomeres are added in series. You can see on this diagram on the left here the difference between a normal heart and in the dilated heart on the right. What you see on the heart in the left side here is a normal volume for the ventricles and a normal volume for the atrium. So you can use that as a reference for what you are seeing in the dilated cardiomyopathies. On the right here, we are seeing a very enlarged left ventricle that is due to stretching of these muscle fibers and that heart chamber is enlarging. You are actually also seeing a little bit of a decrease in the size of the right ventricle and that is due to that left ventricle becoming so big that it is taking up the space of the right ventricle. So what causes a dilated cardiomyopathy? Well, a bunch of stuff can cause this cardiac dilation and in fact that is a perfect mnemonic for remembering what causes this. A, B, C, C, C, D and then I also add a plus on the end here. But we can remember this as a bunch of stuff can cause cardiac dilation. A, B, C, C, C, D and then I add that plus to remind me that there is more than just these six things that can cause cardiac dilation. So the A stands for alcohol. B is wet berry berry. Now remember wet berry berry is due to a B1 deficiency which is thiamine. C stands for coxsackie B and the coxsackie B virus as well as intro virus can cause a viral myocarditis that can then lead to a dilated cardiomyopathy. The next C is cocaine followed by the last C of chagas disease and chagas disease can be other parasitic infections besides chagas disease but that is one of the causes of a dilated cardiomyopathy in regards to parasitic infections. A dilated cardiomyopathy can also be due to drugs and specifically doxorubicin. Now remember doxorubicin is a cancer treatment drug and that is one of the side effects of doxorubicin is a dilation or dilated cardiomyopathy. And then the plus comes in because we have two further things. Pregnancy can cause a dilated cardiomyopathy and then idiopathic. There can be many dilations of the heart that we just don't know what really causes it yet. So that is also an option for further causes. But in regards to the USMLE they are going to ask you something more than likely in one of these six areas because these are the most common causes of a dilated cardiomyopathy. So as we said earlier the dilated cardiomyopathy causes an eccentric hypertrophy. This is where we have our sarcomeres added in series. To treat the dilated cardiomyopathy we use many different treatments. All of these are acting alongside of each other to help increase the function of the heart and decrease the side effects. So sodium restriction is our first treatment that we use. We'll also use ACE inhibitors, beta blockers, diuretics to decrease that preload and afterload on the heart. We're just going to take some fluid out. We can use a mineral corticoid receptor blocker such as spironolactone. And how this works is aldosterone prevents the uptake of norepinephrine and it also promotes structural remodeling of the heart. So with using spironolactone which blocks aldosterone receptors that helps us improve the left ventricular remodeling in patients that have a dilated cardiomyopathy. Dejoxin it's a positive ionotrope so that helps us with contractility. And if many of these options don't work we could end up having to go to an implantable cardioverter defibrillator or ICD and that can go in and help control the rhythm of the heart. And finally if none of these work or we're having continuous problems or side effects that aren't desirable we can continue on into a heart transplant. Obviously that's going to be the final stage of this heart failure and the need for a new heart to replace the broken and malfunctioning heart. Speaking of broken heart there is another cardiomyopathy that's similar to a dilated cardiomyopathy called a tachetsubocardiomyopathy. This is also known as broken heart syndrome. What happens here is we have some severe hypokinesis of the mid ventricular wall segments areas in this direction here where the heart is not actually contracting. So we're preserving the function of the heart and the apical and the basal areas of the heart but in the septum we're not getting any function or movement. So on echocardiogram you actually see this shape that looks like a heart that has broken. So we call this the broken heart syndrome. This is often brought on by periods of high stress. So sometimes in a breakup or in a relationship or in a marriage or loss of a loved one due to that severe stress we can see the broken heart syndrome come up.