Baroflex failure usually causes a loss of the buffering of blood pressure and volatility of BP and heart rate.
Baroflex failure can be documented by the inability of infusions of pressor and depressor drugs to cause reflex bradycardia and tachycardia.25 mmHg or higher. If you have a heart rate drop of 25 mmHg it indicates baroflex control of heart rate.
They can put you in a supine position(laying down) and inject you with phenylephrine and increase the dose until your systolic BP raises 25 mmHg or higher. If you have a heart rate drop of 25 mmHg it indicates baroflex control of heart rate.
They have also injected people with nitroprusside until your systolic BP drops by 25mmHg and causes a change in HR.
Apparently, there can be several causes of Baroflex failure. Some of the people in the study had previously had surgical damage of the glossopharyngeal nerve because of a neck injury. And some had radiation of the pharynx that caused problems and some other people had familial paraganglioma syndrome, which is a genetic problem that causes benign non-catecholamine producing tumors of the carotid body and glomus jugulare and glomus vagale. The tumors damage the glossopharyngeal and vagus nerves. One person also had cell loss in the nuclei of the solitary tracts of the brain stem that had been caused by a degenerative neurologic disorder. But some of the patients they coudn't find a cause for their baroflex failure.
I certainly hope there is some other way to find out if you have it besides being injected with stuff.
After they did the injection part of the test, the patients were monitored. In contrast to the 24-hour urine test I had, during the study they measured catecholamines were measured every so often. And the BP was taken every 4 hours in supine and upright positions and anytime they had symptoms.
They also did cold pressor tests. This is when they have you to put your right hand in a basin filled half with ice and half with water and keep it there for 1 minute. They measure your heart rate before and after. They did math tests by having people count backward from 200 by sevens. And they measured BP before and after this. And there is also a test called the isometric handgrip.
They also gave patients propranolol and atropine in order to measure sympathetic and parasympathetic responses that control heart rate. They gave them Clonidine and monitored BP afterward to see how it affected reduced the sympathetic response.
The patients BP would rise dramatically due to the cold pressor and math tests, which basically caused some mental stress.Some patients had increased nervousness or depression after they became ill. And it was worse with the patients with the worst BP elevation. When their BP was up, they had a sensation of flushing and were pale. They had palpitations and headache and sweating pheochromocytoma. But they had previously had this ruled out by urine and blood tests and radiographic tests and also by the improvement, or at least the absence of an increase, in hypertensive episodes during follow-up.
These patients had higher systolic BP than normal people. But they also had lower than normal BP at night, that "extreme dipper" thing. Their heart rates were also abnormal. Some of them had HR of 90 beats a minute, which could be from loss of parasympathetic control of the heart rate, caused by damage to the right vagal nerve.
When they were measuring the norepinephrine during the tests, they were much higher than normal. And they raised in some patients to more than 200 pg per milliliter (1.1 nmol per liter). Urinary excretion of epinephrine plus norepinephrine averaged 118 μg per 24 hours (697 nmol per 24 hours), more than twice normal (P = 0.015).
The cold pressor test caused a hypertensive paroxysm in some of the patients and lasted for a long time after they removed their hand from the cold water. That means their BP raised to a volatile level.
They were able to show a greater drop in BP during bouts of hypertension with Clonidine, more so than when their BP was at normal levels. Their norepinephrine levels decreased substantially too.
I would think that indicates that Clonidine is a pretty good treatment for it.
Propanolol didn't do much when the BP and heart rate was low in patients. But when they had tachycardia it would decrease the HR by about 12 beats a minute.
The study says that most of the patients could be treated with Clonidine and that many of them could eventually decrease the dosage after 2-4 years, and go onto diazepam 5mg three times a day.
It refers to an earlier study that concluded that baroflex failure could be differentiated from pheochromocytoma because pheochromocytoma doesn't respond to clonidine treatment.
They concluded the paper by saying that baroflex failure symptoms range from patients that have an acute hypertensive crisis to patients that have what they called habitual volatility of blood pressure and with heart rate and high BP surges in response to stress. But they could be punctuated by periods of normal or even low BP during rest. And that it is important to differentiate baroflex failure from other causes in order to treat the orthostatic HYPERtension properly.
Here is some information about people who are "extreme dippers" This medical journal article says that these extreme drops in BP at night are closely related to the abnormalities of autonomic nervous activity.
They defined orthostatic HYPERtension slightly differently than other places. They said it was a systolic BP rise of 10 mmHg when in the upright or standing position after 6-10 minutes. Whereas the above definitions required a 20 mmHg raise.
It also says that orthostatic HYPERtension isn't well known and that it hasn't been well defined. Some places define it as a rise from 90mmHg to above 90 mmHg. And that the older patients had higher systolic BP and lower diastolic BP.
"Although orthostatic hypotension is well recognized and commonly encountered, there are only a few reports of orthostatic hypertension. Most of the reported cases of orthostatic hypertension were related to excessive venous pooling, with an initial drop in cardiac output followed by overcompensation with an excessive release of catecholamines, or to nephroptosis, (also called floating kidney or renal ptosis is an abnormal condition in which the kidney drops down into the pelvis when the patient stands up.) with orthostatic activation of the renin-angiotensin system."
In this study, again from the American Heart Association, the patient had normal plasma and urinary catecholamines and renin release. Pharmacological tests of autonomic nervous system function showed an increased pressor sensitivity to norepinephrine (11 to 14 times normal), normal sensitivity to isoproterenol, diminished baroreceptor reflex sensitivity, and exquisite sensitivity to alpha blockers. This unusual case of orthostatic hypertension appears to be secondary to vascular adrenergic hypersensitivity. It also goes with the rise from 90 mmHg to above 90 mmHg on upright position. And refers to a man who had previously had orthostatic HYPOtension that was followed by HYPERtension. That is precisely what happened to me.
"Autonomic evaluation demonstrated diminished baroreflex sensitivity and an exaggerated pressor response to the cold pressor test and Valsalva phase 2. Combined autonomic blockade with propranolol and atropine abolished the postural BP changes. These data suggested that the exaggerated pressor response was due to an increase in systemic vascular resistance in excess of the demands arising from a transient postural fall in cardiac output."
They used the Valsalva maneuver to indicate baroflex failure. It is the action of attempting to exhale with the nostrils and mouth, or the glottis, closed. This increases pressure in the middle ear and the chest, as when bracing to lift heavy objects, and is used as a means of equalizing pressure in the ears. When you do that your pulse is supposed to drop when you let your breath out.
Just out of curiosity, I did this and my heart rate actually went up instead of down after I let my breath back out. I have one of those wristbands that measures your heart rate and steps and how many hours you are sleeping. It made my ears pop a lot. I repeated it and got the same response. (not a picture of me)
"Orthostatic hypertension is also associated with morning blood pressure surge and extreme nocturnal blood pressure dipping, both of which increase the pulsatile haemodynamic stress of central arterial pressure and blood flow in patients with systemic haemodynamic atherothrombotic syndrome."Orthostatic hypertension—a new haemodynamic cardiovascular risk factor
There is still a lot of information here to absorb, even after I attempted to condense it. But I hope it is helpful to someone. I will be rereading it myself to try and get a grip on it.
I appologize for some of the weird formatting of this post. I don't know if it is something wrong with blogger or is related to the photos I included or what. I attempted to fix it about six times.
Don't forget to watch the POTS videos at the bottom of the blog. You have to scroll down for them.