Question:
My brother is 59 and has been diagnosed with beginning dementia. He has always had low BP. In the past few years he has had a few episodes of syncope. I thought it was seizures. Then I heard it could be heart so we went to cardiologist and he has an implanted monitor (better that seize med I think). Now he still experiences dizzy spells (but not complete syncope) and when I send a report, his heart rate is 40. Is there a higher incidence of people with DS needing a pacemaker? Any precautions to consider before going with that option? Thanks so very much.
Answer:
Blood pressure and heart rates/pulses that are on the lower end of normal or even a little lower than normal are common findings in people with Down syndrome (see references 1 and 2 below). Much of the control of our heart rate and blood pressure is through the autonomic nervous system (the part of the nervous system that controls body functions without us thinking about them). The findings of lower blood pressure and pulse seem to be due to differences in the function of the autonomic nervous systems of people with Down syndrome. Most people with Down syndrome do not experience negative effects from these findings. In fact, a positive of this difference is that hypertension (high blood pressure) is an infrequent finding in people with Down syndrome.
However, blood pressure and pulses that are too low can be problematic for some people with Down syndrome. When the heart rate and blood pressure go too low, an individual can pass out or faint. This is called syncope (more information can be found in reference 3). Often, this is due to the differences of the function of the autonomic nervous system. When we are in pain, frightened or anxious it is typical for our pulse and blood pressure to go down and we may pass out (vasovagal syncope). This response appears to be exaggerated or heightened in some people with Down syndrome.
It is important to remember that not all syncope in people with Down syndrome can solely be explained by differences in autonomic nervous system function. Additional factors need to be considered. For example, our experience is that many people with Down syndrome don’t drink enough fluids and are often (at least mildly) dehydrated which can contribute to syncope. When someone is dehydrated, a normally functioning autonomic nervous system will respond by raising the heart rate and blood pressure. In people with Down syndrome, these compensatory measures also seem to be different, less sensitive, or less functional. Therefore, additional factors like dehydration will increase the chance that a person with Down syndrome will faint. For many people with Down syndrome this is not a serious underlying condition and it can be managed with drinking more fluids and not restricting salt.
Other conditions that can be associated with a lower heart rate, blood pressure, or both leading to syncope include anemia, hypothyroidism, and heart disease (see reference 3). An assessment for these conditions and perhaps other conditions should be done. For some for whom these other conditions have been assessed and addressed, who still tend to have low blood pressure and syncope, medications can be prescribed to raise the blood pressure.
As noted above, heart disease can be a cause of syncope. Some individuals will have a heart rate that is so slow due to heart disease that more intervention is required. Some individuals will require the implantation of a pacemaker. Some young people with Down syndrome and congenital heart disease will require pacemakers as a complication of their congenital heart disease. As people with Down syndrome are living longer, we are also seeing some of our older adults develop more severe changes in the function of the control of their heart rate. As we age, many people’s bodies are not able to maintain a normal heart rate as easily. This appears to be true for some older people with Down syndrome as well. This can occur in both individuals with and without a history of congenital heart disease (see references 4 and 5). Depending on the symptoms, the severity of the low heart rate and blood pressure, and the person’s other health conditions, a pacemaker may be recommended. In our practice, as we have seen more and more older adults with Down syndrome, we have seen more adults with Down syndrome require pacemakers. In our experience, the insertion of a pacemaker can generally be done safely in people with Down syndrome but a discussion with the person’s health care team (primary doctor, cardiologist, and possibly cardiovascular surgeon) to review the indications of implanting the pacemaker, the overall health of the individual, and the risks of the procedure is recommended.
One additional finding is that there also may be a connection between low blood pressure and Alzheimer’s disease (see reference 6). The nature of the connection has not been determined yet. Does low blood pressure contribute to the onset of Alzheimer’s disease? Does developing Alzheimer’s disease impair the body’s ability to control blood pressure and pulse? We do know that both low blood pressure and Alzheimer’s disease occur more commonly in people with Down syndrome. However, it is not clear that one causes the other. In our experience, we have seen a number of people with Down syndrome who developed Alzheimer’s disease who also developed abnormally low heart rates and blood pressures that required treatment. However, like the question of the chicken and the egg, it is often not clear which came first, or which may have caused the other. We do suspect, in at least some individuals, the development of Alzheimer’s disease not only results in impaired cognition but also in impairment of the autonomic nervous system leading to symptoms associated with lower heart rate and pulse.
One more issue noted in the question above was seizures. Seizures do occur more commonly in people with Down syndrome than in others, particularly in people with Down syndrome who develop Alzheimer’s disease. Depending on the presentation of the apparent “passing out,” an evaluation for seizures may also be indicated.
In an older person with Down syndrome who is experiencing dizziness, a thorough evaluation for a variety of causes is recommended. In some individuals a pacemaker may be required and discussion with the person’s health care team is recommended.
References:
- Hypertension and Hypotension
- Diminished Blood Pressure Profiles in Children with Down Syndrome
- Vasovagal Syncope
- Facts about Atrioventricular Septal Defect
- Sinoatrial Node Disease in Adults with Down Syndrome
- Low Blood Pressure in Down’s Syndrome: A Link with Alzheimer’s Disease
- Low Blood Pressure Could Be a Culprit in Dementia, Studies Suggest
- Low Blood Pressure and Risk of Dementia in the Kungsholmen Project