Results from a recent Danish study indicate that otherwise healthy HIV-positive individuals may have moderate dysfunction of the nervous system that affects the heart rate, even after years of antiretroviral therapy. In particular, the researchers found that people with HIV had significantly higher resting heart rates and lower heart rate variability compared to HIV-negative individuals.
Additionally, the moderate nervous dysfunction (known as autonomic dysfunction) was associated with higher blood sugar and cholesterol levels, although this was not the case for HIV-negative study participants.
Based on their results, the study authors recommended close monitoring and maintenance of blood sugar and cholesterol levels in people with HIV. They also suggested that further studies be conducted to understand why HIV-positive individuals might be more sensitive to the effects on the nervous system of changes in blood sugar and cholesterol levels.
Autonomic dysfunction is a malfunction of the body’s autonomic nervous system, which controls automatic functions such as heart rate, digestion, and perspiration. Autonomic dysfunction is linked to an increased risk of heart problems.
In particular, heart rate and heart rate variability, or how the time interval between heart beats varies, are linked to measures of congestive heart failure, damage from diabetes, and mortality risk after a heart attack. Normally the heart rate should vary according to certain signals from the body, such as respiration rate or stress levels; lower variability can indicate problems with the autonomic nervous system.
According to the study authors, results from previous studies have shown evidence of autonomic dysfunction in people with HIV, especially individuals with advanced HIV or AIDS. However, there have been few studies investigating autonomic dysfunction in HIV-positive individuals whose HIV is well controlled with antiretroviral therapy.
Although antiretrovirals have the potential to reduce damage to the nervous system caused by HIV, they have also been implicated in high cholesterol levels and pre-diabetes, which could themselves cause autonomic nervous system damage.
In this study, the authors investigated the presence of autonomic dysfunction, as measured by heart rate and heart rate variability, in HIV-positive individuals who had been on antiretroviral therapy for at least one year.
The study included 97 HIV-positive individuals and 52 age- and gender-matched HIV-negative individuals. Participants with HIV had been HIV positive for a median of 11 years and had taken antiretrovirals for a median of seven years; all but one had viral loads (amount of HIV in the blood) of less than 400 copies per milliliter.
None of the participants had any history of heart disease, diabetes, or were taking medication for high blood pressure.
In order to measure heart rate and heart rate variability, the researchers performed an electrocardiogram on each participant for 15 minutes after an initial 10-minute resting period.
The researchers found evidence of moderate autonomic dysfunction in the HIV-positive study group compared to the HIV-negative study group. In particular, HIV-positive participants had faster heart rates than HIV-negative participants, with the time between heartbeats an average of 77 milliseconds (about 8 percent) shorter.
In addition, the heart rate variability was around 10 percent lower in HIV-positive individuals compared to HIV-negative individuals.
Results also showed that the dysfunction was linked to higher blood sugar and cholesterol levels, but only in the HIV-positive participants.
There was no link between dysfunction and duration of HIV infection, viral load, CD4 (white blood cell) count, or duration or type of antiretroviral therapy.
For more information, please see the study in PLoS One.
Copyright © 2011 The AIDS Beacon
The Autonomic Nervous System. Part II. Dysfunctions
Disorders of the Autonomic Nervous System
No comments:
Post a Comment