Sleep Apnea Hypertension Pathophysiology

Secondary hypertension

With primary hypertension you've got this high blood pressure. And well, ultimately thecause is unknown, right. We've got this big laundrylist of risk factors that might contribute. But really we don't knowexactly what did it. With secondary hypertension, the difference is we know exactly

what's causing yourblood pressure to rise. And we can pinpoint thisother medical condition. So the hypertension happens secondary to some other disease. This form of hypertensionaccounts for only about 10% of hypertension cases. And so it's not that common, right, whereas the other 90%have primary hypertension.

So let's sort of justdive right in to some of the common diseases thatcan lead to hypertension. All right, so renal diseasestend to be big time culprits for secondary hypertension. Where when we say renal, we'rereferring to the kidneys. With these, the kidneys don'tfunction as they normally do. So since they're such huge players in regulating blood pressure

through water and sodium regulation, if you've got some kind ofunderlying kidney problem, it can result in this inabilityto get rid of some fluid. And so more fluid in your body leads to higher plasma and blood volume and so higher blood pressure, because remember, flow andresistance in the blood vessels is directly related to blood pressure.

So if you increase flow,you increase blood pressure. And one potential culpritfor kidney diseases is polycystic kidney disease. By looking at poly, we knowthat that means many, right. And cystic refers to cysts which are like these fluidfilled sacs. So this is an inherited condition where you develop these fluidfilled sacs

all around your kidneys. And if these guys get too bigor there are too many of them, they can start to damage ordisrupt your kidney's function, which can cause you tohold on to more fluid, and this will increaseyour blood pressure. Another renal diseaseis glomerular disease. And your glomeruli in your kidneys are like these filters forwaste and salt or sodium.

Sleep Apnea Sleep Deprivation and Obesity

Hi I'm Ananth Karumanchi, a nephrologist at Beth Israel Deaconess Medical Center and a professor of medicineat Harvard Medical School. I'm Virend Somers a cardiologistand professor of medicine at Mayo in Rochester. Somers, why should the hypertension community care about sleepé So, sleep and blood pressure

are very closely linked. Basically, in a physiologic sense, when people fall asleepthe blood pressure falls. What we know is if yourblood pressure doesn't fall at night when you're sleeping you fall into the nondipper category and that puts you at an increased risk of cardiovascular imports.

We also know that if youhave problems during sleep, if you develop obstructive sleep apnea, it will raise your blood pressure at night and raise your blood pressureeven during the day time. And the third compelling reason to care is that people who are sleep deprived don't get enough sleep at night, whether it's by choice

or whether it's by some external course, these people chronically will tend to have higher blood pressures than those who sleep normally. So, in your opinion, do all patients with hypertension would you recommend them to get a screen for some sort of sleep abnormalities.

No, no I wouldn't becausethe number of people with hypertension is so huge that logistically andeconomically wouldn't be feasible to study all these people. So we need to be veryselective on who we study and some of the points tothink about who we study would be people who have witnesses apneas, meaning the wife or husband says

I see him or her stopbreathing during sleep. That's called a witnessed apnea and a great sign of obstructive apnea. The other is if you hypertensive and you have day time somnolence. If you fall asleep duringthe day time very easily, then you quite likely have sleep apnea. If you have significant obesity,

Pulmonary hypertension diagnosis

So, threading a catheter directly into the heartmight be the most direct way, the gold standard, of measuringpulmonary hypertension, but there are certainlyother ways we can do it. So, if we think about the relationship of the heart and lungs inthe cardiovascular system, we have the heart here, and the lungs, the next step in where the blood is going,

so here we have our lungs. In blood, or deoxygenated blood, well, first let's draw some chambers. We have four chambers, two on top, and two on the bottom. It's from this right ventricle that we get deoxygenatedblue blood into the lungs. Remember that everything's flipped,

like the person isstanding in front of you, so this is the right,and this is the left. So, blood goes from the rightventricle into the lungs, and then back over into the left atrium. It's gonna be oxygenated red blood. So given this relationship, if we have hypertension in the lungs, that backs up into the right ventricle,

and then, not putting as muchforward into the left atrium, then, another way of evaluating the heart can tell us about pulmonary hypertension. And this is a task we call echocardiogram, usually just echo for short. So, echocardiogram. This test is basicallyputting an ultrasound probe over the heart in different directions,

and just looking at howthe chambers in a different compartment of the heart are working. So, for our purposes ofpulmonary hypertension test, the echocardiogram can showus the right ventricle. The flow going on in there,how hard it's working, will give us a clue ofpulmonary hypertension. We can also see the left atrium, see how much blood it's receiving.

So this is a very powerful diagnostic tool in pulmonary hypertension, is to look at how theheart is functioning. But an added bonus, isthat, since we can see ALL parts of the heart, we canalso see the left ventricle, and remember that, if theleft ventricle has a problem pushing blood forward,then the backup can be a cause of pulmonary hypertension.

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