Submitted on September 7, 2004
Accepted on May 24, 2005
Viscerosensory-cardiovascular reflexes: altered baroreflex sensitivity in irritable bowel syndrome
Patrick P. J van der Veek1, Cees A Swenne2*, Hedde van de Vooren2, Annelies L Schoneveld3, Roberto Maestri4, and Ad A. M Masclee1
1 Gastroenterology and Hepatology, Leiden University Medical Center, Leiden, The Netherlands
2 Cardiology, Leiden University Medical Center, Leiden, The Netherlands
3 Leiden Foundation for ECG analysis (SEAL), Leiden, The Netherlands
4 Biomedical Engineering, S. Maugeri Foundation - IRCCS, Scientific Institute of Montescano, Montescano, Italy
* To whom correspondence should be addressed. E-mail: C.A.Swenne{at}lumc.nl.
Background: Animal studies have demonstrated that visceral afferent stimulation alters autonomic cardiovascular reflexes. This mechanism might play an important role in the pathophysiology of conditions associated with visceral hypersensitivity, such as irritable bowel syndrome (IBS). As such studies in humans are lacking, we measured viscerosensory-cardiovascular reflex interactions in IBS patients and healthy controls. Methods: Blood pressure (SBP), heart rate (HR) and arterial baroreflex sensitivity (BRS) were studied in 87 IBS patients and 36 healthy controls under baseline conditions and during mild (15 mmHg) and intense (35 mmHg) visceral stimulation by rectal balloon distension. BRS was computed from continuous ECG and arterial blood pressure signals (Finapres-method) during 5 min periods of 15/min metronome respiration. Results: Baseline SBP and HR were not different between patients and controls. In both groups, SBP increased similarly during rectal stimulation, whereas HR decreased during mild and increased during intense stimulation. BRS was significantly higher in patients compared to controls at baseline (7.9 ± 5.4 vs. 5.7 ± 3.7 ms/mmHg, P=0.03) and increased significantly in both groups during mild stimulation. This increase persisted in controls during intense stimulation, but BRS returned to baseline in patients. BRS was not significantly different between groups during rectal distension. Conclusion: This study demonstrates the presence of a viscerosensory-cardiovascular reflex in healthy individuals and in IBS patients. The increased BRS in IBS patients at baseline may either be a training-effect (frequent challenging of the reflex) or reflects altered viscerosensory processing at the nucleus tracti solitarii.
