Neurogenic Orthostatic Hypotension: Discussion by Brian Olshansky, MD and Suzy Feigofsky, MD

Watch the video for this transcript here.

Dr. Suzy Feigofsky: Hi, I'm Dr. Suzy Feigofsky with the Iowa Heart Center in Carroll. I'm here today with Dr. Brian Olshansky, who needs no introduction. We're going to discuss neurogenic orthostatic hypotension, also known as NOH. Brian, why don't you start by defining neurogenic orthostatic hypotension for the audience?

Dr. Brian Olshansky: Sure, Suzy. It's great to be here with you today.

Neurogenic orthostatic hypotension, or NOH, is a drop in blood pressure upon standing, with little or no change in heart rate. It's due to autonomic dysfunction. NOH is common in patients with Parkinson's disease, pure autonomic failure, and multiple system atrophy. When a person stands up, up to a liter of blood shifts from the upper part of the body to the lower part of the body. This shift causes decreased return of blood to the heart. To compensate, sympathetic activation occurs.

In healthy individuals, sympathetically mediated norepinephrine release triggers peripheral and splanchnic vasoconstriction and increases heart rate and contractility slightly, to restore normotension within seconds of standing. Patients with NOH have a dysfunctional autonomic response, resulting in inadequate peripheral release of norepinephrine. Because the body can no longer compensate for the shift in blood volume, a person with NOH experiences a drop in blood pressure leading to organ hypoperfusion.

Symptoms, such as dizziness, lightheadedness, and syncope are common due to brain hypoperfusion.

Dr. Feigofsky: When I was in training, I didn't learn a lot about this. I suspect some of our colleagues didn't as well. In your opinion, which patients should we be evaluating for NOH?

Dr. Olshansky: It's important to know what to look for, and who to look for. Patients should be evaluated for NOH if they have a disorder associated with autonomic dysfunction, such as Parkinson's disease, or if they've experienced unexplained falls or syncope, or if they report any of a number of symptoms that occur only while standing.

These patients tend to be older men, and many have multiple comorbidities. Notably, the symptoms of NOH, such as dizziness, lightheadedness, and syncope, can also be symptoms of other cardiovascular conditions. In some of these instances, disturbing symptoms can be misdiagnosed.

The case history we worked on for EP Lab Digest is a great example of how dizziness upon standing can help point clinicians to evaluate for and diagnose NOH.

Dr. Feigofsky: In this scenario that we presented for EP Lab Digest, she was different. She wasn't an older man, as we had talked about. She was a younger woman who had syncope and this history of primary pulmonary hypertension. What in her story made you consider NOH as part of that differential?

Dr. Olshansky: I agree, not all patients that have NOH are older men, and they don't necessarily have multiple comorbidities. In fact, she was referred because on ultra monitors, she had short runs of super ventricular tachycardia that were thought to be cause for her symptoms.

The patient was actually referred for the possibility of an ablation. In essence, she was a 46-year-old woman with recurrent weakness, dizziness, and loss of consciousness. Syncope was either sudden or preceded by dizziness or lightheadedness.

Besides primary pulmonary hypertension, as you mentioned, she had palpitations, non-sustained supraventricular tachycardia, and peripheral edema, for which she was being treated with furosemide. Honestly, I wasn't sure how to treat her until she suddenly stood up and then nearly passed out.

Dr. Feigofsky: Aha! That's what made you think about orthostatic hypotension.

Dr. Olshansky: That's right. It was serendipitous. Otherwise, I might not have picked it up. I was beside myself thinking she might need an EP study and an ablation, and how to change my entire thinking about her problems.

Dr. Feigofsky: How did you evaluate her for orthostatic hypotension?

Dr. Olshansky: The first step was to take her blood pressure and heart rate while she was supine. Then take her blood pressure again and her heart rate again while she was standing. Now, the definition for orthostatic hypotension is the following: if the blood pressure drops at least 20 millimeters of mercury systolic, or 10 millimeters of mercury diastolic, at three minutes, that would indicate orthostatic hypotension.

If her heart rate didn't increase much upon standing, despite a blood pressure drop, this could indicate NOH. Of course, it was critical to evaluate any symptoms that she had concurrently.

Dr. Feigofsky: In this case, did the patient meet criteria for NOH?

Dr. Olshansky: That's correct, Suzy. That's exactly what she had. Her blood pressure dropped from 130/80 to 88/40 upon standing, and her heart rate only increased eight beats per minute. She felt very lightheaded and dizzy with that blood pressure drop, and then she had to sit down before she nearly passed out.

Dr. Feigofsky: How do you approach a patient who has syncope likely due to NOH and also primary pulmonary hypertension? They seem to be very complicated issues that have be managed rather delicately.

Dr. Olshansky: I agree with you completely, Suzy. These patients are not easy to manage. First, any patient with NOH could benefit from adjusting the doses or eliminating unnecessary causative medications, and also from making sure that the patient is properly hydrated. Compression garments that extend above the waistline, and elevating the head of the bed at night to an angle of over 30 degrees, is often helpful. Management of this patient was complex in addition, because she had primary pulmonary hypertension.

Like NOH, primary pulmonary hypertension can be associated with autonomic disorders. The question then becomes, how do you safely treat NOH without exacerbating or interfering with treatments for primary pulmonary hypertension?

You might also consider whether these two conditions are actually related. It's important to keep in mind that cardiovascular patients with OH may already have an increased risk for morbidity and mortality. My treatment plan for this patient took into account the need to constrict the peripheral vasculature without adversely affecting the pulmonary vasculature. For example, I would not prescribe fludrocortisone in combination with a diuretic like furosemide.

Both droxidopa and midodrine can produce peripheral vasoconstriction, and could be alternatives that may have limited effects on the pulmonary vasculature. Several therapies were tried, and finally, we settled on droxidopa.

Dr. Feigofsky: In this case, for those of our colleagues who may be watching, what do you think is the most important takeaway?

Dr. Olshansky: First, silly as it may sound, Suzy, it's important to assess the patient with undiagnosed symptoms before jumping to conclusions from non-diagnostic testing.

Second, the evaluation does not necessarily need to be complex. A careful history and physical examination with orthostatic vital signs was crucial here, and inexpensive, before taking clinical steps such as implanting a loop recorder, or other more invasive diagnostic procedures. Arrhythmias may be present but unrelated to the patient's main complaints. Orthostatic hypotension should be an early consideration in the diagnostic process.

Dr. Feigofsky: What I'm hearing is that it's important to screen for orthostatic hypotension in many clinical scenarios. I think, as electrophysiologists, we tend to focus on rhythm disturbances as a cause for symptoms. When would you recommend obtaining orthostatic vital signs? Do you obtain orthostatics in all of your patients with syncope?

Dr. Olshansky: I agree with you, Suzy. Many times we overlook what appears to be staring us straight in the face. If somebody has episodes of feeling like they're dizzy, lightheaded, or going to pass out when they stand up, this would be a clue that the problem is related to NOH.

This case really had me wondering how many other patients have undiagnosed NOH and aren't receiving appropriate management.

Dr. Feigofsky: I'm with you on that, Dr. O. Thank you.

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