Welcome to lecture 17 of our course, hypertrophic cardiomyopathy. hypertrophic cardiomyopathy. While one of the most common cardiomyopathy these is not the only one. And the reason why we chose to single it out in a lecture are its unique features that are frequently relevant in the acute or emergency setting. hypertrophic cardiomyopathy is a familiar disorder, usually with an autosomal dominant pattern of inheritance. In simple terms, it means Lv hypertrophy in the absence of another cause.
There are a set of diagnostic criteria by echo but for the sake of simplicity, we'll just select the simplest and most important criterion Lv wall thickness equal to above 1.5 centimeters in the absence of other causes of Lv hypertrophy, such as systemic hypertension or Eric stenosis. This is an example of paraspinal long x view of a patient with hypertrophic cardiomyopathy. This patient also happens to have infective endocarditis. You can see the vegetation on the mitral valve known dilated left atrium, which is one of the features of hypertrophic cardiomyopathy, which help us to distinguish it from athletic heart. We'll get to that later. This is a pair of sternal, short axis, mid level, mid Lv level view of the same patient with hypertrophic cardiomyopathy, and you can see how the Lv cavity almost gets obliterated insistently.
Again, a small Lv cavity is another feature of hypertrophic cardiomyopathy to differentiate from athlete's hearts. This is an atypical for chamber view, the same patient. Again, you can see the vegetations on the mitral valve and you can see the dilated left atrium and you can see how the cavity is almost obliterated insistently. Why do we care so much about hypertrophic cardiomyopathy? Well, because aside from the increased rate of arrhythmia and sudden cardiac death, hypertrophic cardiomyopathy has several important mechanical effects, First, and most importantly, the hyperactive of the lb septum can cause narrowing of the Lv OT, in many cases up to the point of causing significant obstruction, particularly insistently when the septum contracts and thickens even more. In this case, the cardiomyopathy is called hypertrophic obstructive cardiomyopathy, or h o cm, usually pronounced hokum on echo.
We can see it in 2d when we place color Doppler on the LVT and you can see the aliasing on the T and sisterly indicating turbulent flow. Again know the small Lv cavity and the dilated left atrium. to ascertain the elevated LDL gradients. We place pulse wave Doppler on the LBT. And this is an example of a classic Lv ot pulse wave Doppler trace and in how patient it has a characteristic shape which we call the dagger shape because it resembled a dagger obviously, and a p gradient over 30 millimeters of mercury is diagnostic of obstruction. Sometimes the gradient may not reach 30 millimeters of mercury at risk but instructing the patient to perform the valsalva maneuver will bring the gradient up and confirm the diagnosis.
Tachycardia and hypovolemia. Similar to the valsalva maneuver, accentuate the obstruction by emptying the Lv, reducing the already small Lv cavity size and consequently narrowing the Lv, the Lv ot further. This leads to reduction of stroke volume and further hypotension, which in turn causes more obstruction and a vicious circle ensues. In this case, the patient will present with shock, and you should resist the urge to use basil pressors and instead give IV fluids and bring down the heart rate. Basil pressors will worsen the tachycardia increasing the obstruction and perpetuating the shock. The second mechanical effect is that the mark hypertrophy makes the whole Lv cavity smaller including the mitral annulus the mitral leaflets which which used to fit a much wider annulus now find themselves redundant prolapse into the left ear During system D, and the resulting multi lactation causes mitral regurgitation, which in some cases can be severe.
In this case, it's fairly mild However, this is just for demonstration. Finally, the excessive Lv hypertrophy is not matched by an equivalent increase in blood supply. And with any increase in myocardial demands such as an exercise, myocardial ischemia can occur and the patient presents with chest pain. Eventually, in long standing, how can patients they'll be will fail, and the patient will go into heart failure. This carries a bad prognosis with immune survival of less than one year. You can see here an example of a patient with severely impaired systolic function this patient presented to us with with heart failure.
Before we wrap up, we need to differentiate between hypertrophic cardiomyopathy and athlete's heart because both of them can have similar appearances on echo and we come across both of them in roughly the same age group. So there are several clues which can help us to friendship between the two the echo findings in hypertrophic cardiomyopathy, as we mentioned, the LA is usually dilated over 45 millimeters by an athlete's heart. The LA has normal dimensions, which are up to 38 millimeters in females and 40 millimeters in males. Similarly, in hypertrophic cardiomyopathy, the Lv cavity size is small, as we mentioned, less than 45 millimeters while an athlete's heart. The Lv cavity is normal or even upper normal in dimensions. A third clue is that greater than mild Mr is suggestive of hypertrophic cardiomyopathy while an athlete's heart Mr should be mild or even less.
In cases of hypertrophic obstructive cardiomyopathy, we will have Lv ot obstruction. As mentioned, while an athlete's heart, you should never have any significant Lv ot obstruction. Finally, hypertrophic cardiomyopathy will not regress if the athlete stops practicing sports. However, an athlete's heart stopping sport causes the conditioning and regression of the Lv hypertrophy. These are the most important echo findings. There are some additional findings such as an abnormal ECG and hypertrophic cardiomyopathy.
This is a classic ECG of a hypertrophic cardiomyopathy patient, you can see the high voltage and the inverted t waves. In athlete's heart, the ECG should be within normal. Finally, hypertrophic cardiomyopathy, patients will often have family history because it's a genetic condition. While an athlete's heart, they won't usually have any history. That's all we have to say on hypertrophic cardiomyopathy. See you in the next lecture, cardiac trauma