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Updated: Aug 14, 2026
Non-invasive Assessment of Microvascular and Endothelial Function
Published on: January 29, 2013
Vascular function assessed by flow-mediated vasodilation and nitroglycerine-induced vasodilation in subjects with
Aya Mizobuchi1, Tatsuya Maruhashi1, Yusuke Saito1
1Department of Regeneration and Medicine, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, Japan.
Insights
First-degree atrioventricular block (AVB) is linked to impaired blood vessel function, specifically reduced endothelium-dependent vasodilation. This common ECG finding may indicate a poorer prognosis than previously thought.
Area of Science:
- Cardiology
- Vascular Biology
- Electrocardiography
Background:
- First-degree atrioventricular block (AVB) is a frequent electrocardiogram (ECG) finding.
- Vascular dysfunction is a known contributor to cardiovascular disease.
- The relationship between first-degree AVB and vascular function remains understudied.
Purpose of the Study:
- To investigate the association between the PR interval on ECG and vascular function.
- To assess endothelium-dependent and endothelium-independent vasodilation in subjects with and without first-degree AVB.
Main Methods:
- Cross-sectional study of 2220 subjects.
- Vascular function assessed using flow-mediated dilation (FMD) for endothelium-dependent vasodilation.
- Nitroglycerin-induced dilation (NID) for endothelium-independent vasodilation.
- Comparison between 106 subjects with first-degree AVB and 1241 subjects with normal PR interval.
Main Results:
- Subjects with first-degree AVB exhibited significantly lower FMD compared to controls (3.5% vs. 4.9%, P < 0.001).
- This difference in FMD persisted after adjusting for confounding factors (OR: 1.73, P = 0.015).
- While NID was lower in the AVB group, the difference was not significant in multivariate analysis (OR: 1.48, P = 0.117).
Conclusions:
- First-degree AVB is associated with impaired endothelium-dependent vasodilation.
- Endothelium-independent vasodilation was not significantly different between groups after adjustments.
- First-degree AVB may not be a benign ECG finding, suggesting potential vascular implications.
Abstract:
First-degree atrioventricular block (AVB) is a common electrocardiogram finding in clinical practice. Vascular dysfunction is associated with cardiovascular disease and events. There is no information on the association of AVB with vascular function. The purpose of this study was to evaluate the associations of PR interval with vascular function assessed in well-characterized subjects. A total of 2220 subjects were enrolled in this study. We evaluated endothelium-dependent vasodilatation assessed by flow-mediated vasodilation (FMD) and endothelium-independent vasodilatation assessed by nitroglycerine-induced vasodilation (NID) in 106 subjects with first-degree AVB (70 men; mean age, 64.3 ± 12.9 years) and 1241 subjects with normal PR interval (531 men; mean age, 56.1 ± 13.9 years). Subjects with first-degree AVB had a lower FMD value than that in subjects with normal PR interval (3.5 ± 2.4% vs. 4.9 ± 3.3%, P < 0.001). FMD was significantly lower in subjects with first-degree AVB than in subjects with normal PR interval even after adjustment of confounding factors for assessment of endothelium-dependent vasodilatation (OR: 1.73, 95% CI: 1.11-2.70; P = 0.015). Although NID was significantly lower in subjects with first-degree AVB than in subjects with normal PR interval (11.1 ± 6.0% vs. 13.6 ± 6.1%, P < 0.001), there was no significant difference in NID between the two groups in multivariate analysis (OR: 1.48, 95% CI: 0.91-2.41; P = 0.117). Both endothelium-dependent and endothelium-independent vasodilation in the brachial artery are impaired in parallel with the prolongation of atrioventricular conduction. After adjustments of confounding factors for vascular function, first-degree AVB is associated with impaired endothelium-dependent vasodilatation but not with impaired endothelium-independent vasodilatation. From the aspect of vascular function, it is unlikely that first-degree AVB is an electrocardiography abnormality with a good prognosis.
