Plasma Homocysteine and Autonomic Nervous Dysfunction: Association and Clinical Relevance in OSAS

Abstract

<jats:p><jats:italic>Objective</jats:italic>. Elevated plasma homocysteine (Hcy) is an independent risk factor for cardiovascular diseases, but the precise mechanism of Hcy in cardiovascular disease remains elusive. This study is aimed at evaluating the association between Hcy levels and autonomic nervous system and at investigating their clinical relevance in obstructive sleep apnea syndrome (OSAS). <jats:italic>Methods</jats:italic>. A total of 191 subjects with OSAS were enrolled for this cross-sectional study. Heart rate variability (HRV) represents the status of the autonomic nervous system and is a well-known index that allows studying the autonomic modulation. HRV and polysomnography parameters were collected based on Holter monitors and polysomnography system. The software computed all the basic HRV parameters including SDANN, SDNN and pNN50. Correlation analyses between Hcy and HRV parameters and echocardiographic parameters were performed. <jats:italic>Results</jats:italic>. Compared with the mild-moderate OSAS group, the prevalence of male and smoking and Hcy levels were considerably higher in the severe OSAS group (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mi>P</mml:mi><mml:mo>=</mml:mo><mml:mn>0.01</mml:mn></mml:math>, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M2"><mml:mi>P</mml:mi><mml:mo>=</mml:mo><mml:mn>0.02</mml:mn></mml:math>, and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M3"><mml:mi>P</mml:mi><mml:mo>=</mml:mo><mml:mn>0.01</mml:mn></mml:math>, respectively). Also, there were significant linear relationships between Hcy quartiles with the proportion of severe OSAS (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M4"><mml:mi>P</mml:mi><mml:mo>=</mml:mo><mml:mn>0.01</mml:mn></mml:math> for the trend). Interesting, there is a negative linear correlation between SDANN and Hcy quartiles (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M5"><mml:mi>P</mml:mi><mml:mo>=</mml:mo><mml:mn>0.02</mml:mn></mml:math> for the trend). Spearman’s correlation analysis showed a significant negative correlation between SDANN and Hcy levels (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M6"><mml:mi>r</mml:mi><mml:mo>=</mml:mo><mml:mo>−</mml:mo><mml:mn>0.17</mml:mn></mml:math>, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M7"><mml:mi>P</mml:mi><mml:mo>=</mml:mo><mml:mn>0.02</mml:mn></mml:math>). Interestingly, the relationship of it remains significant after adjustment for clinical covariates (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M8"><mml:mi>r</mml:mi><mml:mo>=</mml:mo><mml:mo>−</mml:mo><mml:mn>0.15</mml:mn></mml:math>, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M9"><mml:mi>P</mml:mi><mml:mo>=</mml:mo><mml:mn>0.04</mml:mn></mml:math>). However, echocardiographic parameters were not significantly correlated with Hcy or HRV parameters (all <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M10"><mml:mi>P</mml:mi><mml:mo>&gt;</mml:mo><mml:mn>0.05</mml:mn></mml:math>). <jats:italic>Conclusions</jats:italic>. Elevated plasma Hcy level is linearly correlated with cardiac autonomic nervous function disorders in patients with OSAS.</jats:p>

Association between Cardiac Autonomic Neuropathy and Coronary Artery Lesions in Patients with Type 2 Diabetes

“…A standard two-dimensional Doppler echocardiographic examination was performed in all patients according to routine procedures (GE Vingmed Vivid 7 or Vivid 9, Horten, Norway). The following parameters were obtained as previously reported [ 13 ]. The left ventricular end-diastolic dimension (LVEDD) was measured using M-mode in the parasternal left ventricular long-axis view.…”

“…Heart rate variability (HRV), which reflects the status of the cardiac sympathovagal balance, is a noninvasive, practical, and reproducible index used to assess cardiac autonomic function [ 12 , 13 ]. Recently, more attention has been placed on HRV assessment as a diagnostic tool in the prediction of prognosis in various neurological disorders and in the evaluation of autonomic impairment [ 14 ].…”