Heart Rate Increase, Fall In Blood Pressure Combo Test Can Help Diagnose Brain Diseases

Neurologists have found that a simple bedside test, matching a person’s change in heart rate with a drop in blood pressure after the person stands can indicate early sign of serious neurological diseases. Findings of the study by neurologists at the New York University (NYU) School of Medicine are published in the March issue of Annals of Neurology.

What Makes This Simple Test Significant?

Checking increase in heart rate and drop in blood pressure soon after a person stands is a simple test. However, this simple test has vast implications in the diagnosis of a group of degenerative brain diseases called synucleinopathies. These include Parkinson's disease, Lewy Body dementia, and multiple system atrophy.

Neurological diseases such as these arise from the abnormal buildup of a protein called alpha-synuclein, in the brain. Such debilitating conditions damage the nerves that control blood pressure and heart rate.

"For the first time, we have been able to systematically show that patients whose blood pressure drops after standing up without an accompanying increase in their heart rate may have a synucleinopathy," says lead study author Lucy Norcliffe-Kaufmann, PhD, research assistant professor of neurology, neuroscience and physiology and associate director of NYU Langone Health's Dysautonomia Center. "By taking a patient's blood pressure lying flat, then looking at the change in heart rate after the patient stands up, we can provide healthcare providers with clues as to whether or not the patient has this neurodegenerative disease."

What Does Falling Blood Pressure Signify?
Orthostatic hypotension is a condition wherein there is a fall in blood pressure as soon as a person stands. Falling blood pressure after standing can cause dizziness, lightheadedness and fainting.

When orthostatic hypotension happens because of impaired activation of nerves which squeeze the blood vessels, the condition is known as "neurogenic orthostatic hypotension." This signifies a serious failure in the autonomic nervous system. The autonomic system regulates important functions of the body such as heart rate, breathing, and metabolism. .

Heart rate Increase – Low Blood Pressure Link
Doctors can know the difference between neurogenic and non-neurogenic orthostatic hypotension by measuring a patient's heart rate upon standing. Patients with neurogenic orthostatic hypotension usually have little or no increase in heart rate after standing. On the other hand, patients with non-neurogenic orthostatic hypotension typically have a definite increase in heart rate. .

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Details of the Study
For the study, researchers identified 402 patients with orthostatic hypotension who had a normal heart rhythm. Of these patients, 378 were diagnosed with synucleinopathies. In the remaining 24 patients, orthostatic hypotension was attributed to non-neurological causes such as overmedication with drugs to control blood pressure, anemia, or dehydration. .

Researchers measured the blood pressure of patients while they were lying on a tilting table. The set up mimics standing up and exerts a strain on the blood pressure thereby causing it to fall. It was found that patients with neurogenic orthostatic hypotension had twice the fall in blood pressure, but only a third of the increase in heart rate than patients who had non-neurogenic orthostatic hypotension.

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According to Dr. Norcliffe-Kaufmann, the finding suggests that doctors should measure the blood pressure and heart rate of patients after they stand up, instead of measuring from a seated position in case of patients who complain of fainting or dizziness while standing.

Study Impact on Major Clinics Working Together on Rare Diseases
This study was supported by a National Institutes of Health (NIH) grant (grant no. U54-NS065736) to the Autonomic Disorders Consortium. This is a five-site clinical research initiative of which NYU Langone is a member. Study principal investigator Horacio Kaufmann, MD, Director of NYU Langone's Dysautonomia Center, observes that the new study demonstrates the impact of major clinics in the United States working in collaboration on a rare disease.

Says Dr. Horacio Kaufmann, "This study shows that researchers working on problems in rare diseases, such as blood pressure in synucleinopathies, can pool together data and ideas and develop a simple bedside test that can perhaps help spot these problems earlier." Implications of the simple test should have widespread applicability, say researchers.

Synucleinopathies – Degenerative Nerve Diseases
The nervous system is made up of the brain, spinal cord and nerves and controls all the functions of the body. When something goes even slightly wrong with the nervous system, the person will have trouble in areas of living – breathing, walking, talking, eating or learning. Problems with nerves can also affect a person’s memory, senses and mood.

Synucleinopathies are neurological diseases caused by the abnormal buildup of a protein called alpha-synuclein, in the brain. The three main types of Synucleinopathy are Parkinson’s disease, dementia with Lewy bodies and multiple system atrophy. Synucleinopathies have commonly shared features of parkinsonism (symptoms such as tremor, stiffness and slowness of movement), sleep disorders, serious decline in memory, language and thinking skills and sometimes visual hallucinations.

The current study is significant because for the first time, researchers have a used a simple test to systematically show that patients whose blood pressure drops after standing up without an accompanying increase in their heart rate may have a degenerative nerve disease.

Reference

1. Lucy Norcliffe-Kaufmann, Horacio Kaufmann, Jose-Alberto Palma, Cyndya A. Shibao, Italo Biaggioni, Amanda C. Peltier, Wolfgang Singer, Phillip A. Low, David S. Goldstein, Christopher H. Gibbons, Roy Freeman, David Robertson. 'Orthostatic heart rate changes in patients with autonomic failure caused by neurodegenerative synucleinopathies.' Annals of Neurology, (2018) DOI: 10.1002/ana.25170

Source-Medindia