Impaired cardiac autonomic functions in patients with environmental asbestos exposure: a study of time domain heart rate variability

Our plain-English summary of Impaired cardiac autonomic functions in patients with environmental asbestos exposure: a study of time domain heart rate variability, by H. Pekdemir, A. Camsari, M.N. Akkus, et al (Journal of Electrocardiology, 2003).

The study

• Authors: H. Pekdemir, A. Camsari, M.N. Akkus, D. Cicek, C. Tuncer, Z. Yildirim
• Journal: Journal of Electrocardiology
• Published: 2003;36(3):195-203
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Environmental asbestos exposure is related to diffuse pleural disease (thickening and calcification) and restrictive pulmonary disease. To assess cardiac autonomic system, we investigated the time domain heart rate variability (HRV) by Holter monitoring and their correlation with pulmonary function tests in patients with pleural disease caused by environmental asbestos exposure. We studied 45 patients (26 men, 19 women, aged 62.67 +/- 10.1 years) and 35 healthy patients who had similar sex and age profile to the patients (24 men, 11 women, aged 59.31 +/- 8.4 years). The asbestosis group was divided into 3 subgroups according to the severity of forced vital capacity (FVC) severe (group 1) (n = 12): FVC less than 50% of expected, moderate (group 2) (n = 16): FVC 64%-51% of expected and mild (group 3) (n = 17): FVC 65%-80% of expected. HRV parameters were significantly different among all groups (P<.0001). Comparing the 4 groups (subgroups and control group), group 1 had the lowest mean HRV values and controls had the highest mean HRV values (P<.0001). Severity of autonomic dysfunction was correlated with the severity of FVC and arterial oxygen pressure. Right ventricular end-diastolic internal diameter (RVEDID) and right ventricular end-systolic internal diameter (RVESID) values were significantly increased in patients (P <.0001, P < 0.0001, respectively). Pulmonary acceleration time (AcT) values were shorter in all patient groups than control group (P <.0001). It was shortest in group 1. Group 2 and 3 had shorter AcT values than control group. HRV parameters were correlated positively with AcT values and negatively with RVEDID and RVESID values. In conclusion, patients with restrictive pulmonary disease due to environmental asbestos exposure had autonomic dysfunction, which was correlated with the severity of restriction. This was thought to be the result of chronic hypoxia, pulmonary hypertension, and right ventricular enlargement.

In plain English

This study from Turkey compared heart rate variability, a measure of how the nervous system regulates the heartbeat, in 45 patients with calcified pleural plaques caused by environmental asbestos exposure and 35 healthy volunteers of similar age and sex. The patients came from a county where asbestos minerals, which the article calls "thermolite", were used to insulate houses. Patients were grouped by how much their forced vital capacity, a measure of lung volume, was reduced. Everyone had 24-hour heart monitoring, breathing tests, blood oxygen tests and heart ultrasound. Heart rate variability was lower in all patient groups than in controls. It was lowest in the group with the most reduced lung capacity and was correlated with lung capacity and blood oxygen. Patients had larger right ventricular dimensions and shorter pulmonary acceleration times, a sign the authors linked to pulmonary hypertension. The authors thought the impaired heart rate variability resulted from chronic low blood oxygen, pulmonary hypertension and right ventricle changes. They noted they took no heart tissue biopsies, so they could not evaluate whether asbestos fibers had directly reached the heart muscle.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Comparison of patients with asbestos-related pleural disease (in three subgroups by lung function) against healthy controls, all measured once in the same way; the article does not name the design
• Who was studied: 45 patients with calcified pleural plaques caused by asbestos exposure (26 men, 19 women, mean age 62.67) from a county in Turkey where asbestos minerals were used to insulate houses. Patients were divided by forced vital capacity (FVC) into group 1 (severe, FVC less than 50% of expected; n=12), group 2 (moderate, 51-64%) and group 3 (mild, 65-80%). The comparison group was 35 healthy volunteers (24 men, 11 women, mean age 59.31). The authors work at departments in Mersin, Kahramanmaras and Malatya. Study dates are not given.
• Exposure: Environmental (household) asbestos exposure. In some rural regions, soil rich in asbestos fibers was traditionally used to insulate outdoor and indoor house walls until the end of the 1990s. The article describes the mineral as "thermolite minerals of asbestos". No individual exposure levels were measured.
• Main results:
  • Time domain heart rate variability parameters were lower in all patient groups according to their level of lung restriction, more prominently in groups 1 and 2. Group 1, with the worst FVC, had the lowest heart rate variability values.
  • Heart rate variability parameters were positively correlated with FVC and with arterial oxygen pressure (PaO2).
  • Mean right ventricular end-diastolic and end-systolic internal diameters were significantly increased in patients compared with controls.
  • Pulmonary artery flow acceleration time (AcT) was shorter in all patient groups than in controls, most in group 1. AcT was less than 100 ms in 25 patients and less than 80 ms in 8 patients (5 in group 1, 3 in group 2). The authors cite AcT as a predictor of pulmonary hypertension. However, clinical observations found no signs of hypertension or cor pulmonale in any patient.
  • Heart rate variability parameters correlated positively with AcT and negatively with right ventricular dimensions.
  • Left ventricular ejection fraction was normal in all groups and was not correlated with heart rate variability.
  • CT and HRCT scans showed no interstitial infiltration and no pleural disease causing restriction other than the calcified pleural plaques.
• The authors' conclusion: The authors concluded that heart rate variability was impaired in these patients and that the impairment was correlated with the severity of restrictive lung disease. They thought it resulted from chronic low blood oxygen, pulmonary hypertension and right ventricle changes.
• Limitations the authors state:
  • No endomyocardial (heart tissue) biopsy was done to look for infiltration of the heart muscle by asbestos fibers, so the authors could not evaluate direct asbestos exposure to the heart muscle.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Pleural plaques and thickening.

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Pulmonary Function Test (PFT), Hypoxia, Pulmonary Hypertension.

Related studies

• Metsovo lung: pleural calcification and restrictive lung function in northwestern Greece. Environmental exposure to mineral fiber as etiology — S.H. Constantopoulos, J.A. Goudevenos, et al. (1985)
• Asbestos-induced pleural fibrosis and impaired lung function — D.A. Schwartz, L.J. Fuortes, et al. (1990)
• Signs of asbestosis and impaired pulmonary function in women who worked in shipyards — K.H. Kilburn, R. Warshaw, et al. (1985)
• Metsovo lung outside Metsovo. Endemic pleural calcifications in the ophiolite belts of Greece — S.H. Constantopoulos, P. Theodoracopoulos, et al. (1991)
• Additional proteins in BAL fluid of Metsovites environmentally exposed to asbestos: more evidence of "protection" against neoplasia? — V. Galani, S. Constantopoulos, et al. (2002)
• Pleural calcifications — E. Marchiori, B. Hochhegger, et al. (2018)

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