Clinical Trial: Cardiovascular Effects of Selective I(f)-Channel Blockade

Study Status: Completed
Recruit Status: Unknown status
Study Type: Interventional

Official Title: Einfluss Selektiver I(f)-Blockade Auf Orthostase-Toleranz Und Sympathikusaktivität Bei Gesunden

Brief Summary: The study compares three treatment modalities in a human model of Postural orthostatic tachycardia syndrome (POTS): beta-blockers, I(f)-blockers, and placebo.

Detailed Summary:

Elevated heart rate may lead to cardiac disease in the long-term. Therefore, drugs lowering heart rate are useful. Beta-blockers are an established treatment modality. They not only lower heart rate but also contractility, which might be undesirable in certain tachycardic disorders.

Postural orthostatic tachycardia syndrome (POTS) patients complain about dizziness, weakness, headache, lightheadedness, fatigue, nausea, and presyncope. In some patients there is elevated heart rate even during supine rest. In POTS patients it is preferable to lower heart rate without reducing cardiac contractility which can be achieved by using so-called I(f)-blockers. Thus, they might be superior to beta-blockers in POTS.

In our study, we artificially generate POTS in healthy male subjects for about 48 hours. We want to compare the cardiovascular effects and orthostatic tolerance of the following treatments: beta-blocker, I(f)-blocker, and placebo.

Moreover, we will quantify changes in cardiovascular autonomic regulation brought about by I(f)-blockade versus placebo.


Sponsor: Hannover Medical School

Current Primary Outcome: Sub-study 'Orthostatic tolerance': Change in heart rate after 20 mins of passive orthostasis. Sub-study 'Sympathetic system': arterial pressure related heart rate [ Time Frame: 12-18 hours ]

Original Primary Outcome: Same as current

Current Secondary Outcome:

  • 'Orthostatic tolerance': Hemodynamics during head-up tilt. Time to presyncope. [ Time Frame: 12-18 hours ]
  • 'Sympathetic system': Muscle sympathetic nerve activity (MSNA). [ Time Frame: 12-18 hours ]


Original Secondary Outcome: Same as current

Information By: Hannover Medical School

Dates:
Date Received: March 18, 2009
Date Started: November 2008
Date Completion: December 2010
Last Updated: March 18, 2009
Last Verified: March 2009