Related Experiment Video
Updated: May 24, 2026
14:09
Tilt Testing with Combined Lower Body Negative Pressure: a "Gold Standard" for Measuring Orthostatic Tolerance
Published on: March 21, 2013
MSNA during prolonged post-faint hypotension
J Rozenberg1, W Wieling, I K Schon
1Department of Internal Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands. Josien.Rozenberg@student.uva.nl
Summary
Prolonged post-faint hypotension (PPFH) is not caused by vasodilation or sympathetic withdrawal. Delayed cardiac output recovery, potentially due to increased vagal outflow, is the likely mechanism for this condition.
Area of Science:
- Cardiovascular Physiology
- Autonomic Nervous System Function
- Syncope Pathophysiology
Background:
- Delayed hemodynamic recovery after syncope, termed prolonged post-faint hypotension (PPFH), is increasingly recognized.
- The underlying mechanisms, particularly regarding sympathetic nervous system activity and peripheral vasodilation, remain unclear.
- Previous studies suggest a vagal mechanism, but direct evidence from muscle sympathetic nerve activity (MSNA) is lacking.
Purpose of the Study:
- To investigate the role of muscle sympathetic nerve activity (MSNA) and hemodynamic changes in prolonged post-faint hypotension (PPFH).
- To compare patients with PPFH to those with normal recovery (NR) after tilt-back following syncope.
- To determine if exaggerated vasodilation or sympathetic withdrawal contributes to PPFH.
Main Methods:
- Retrospective analysis of continuous blood pressure (BP) and MSNA recordings during tilt-induced syncope.
- Patients were tilted head-up and administered glyceryl trinitrate (GTN) if needed, then returned to the horizontal position.
- PPFH was defined as systolic BP <85 mmHg for at least 2 minutes post-tilt-back; hemodynamic and MSNA parameters were analyzed at various time points.
Main Results:
- Both PPFH and NR groups showed decreased mean arterial pressure (MAP) post-recovery, but MAP and heart rate (HR) were lower in the PPFH group.
- Cardiac output (CO) remained below baseline in early recovery only in the PPFH group, while total peripheral resistance (TPR) was similar in both groups.
- Muscle sympathetic nerve activity (MSNA) tended to remain elevated above baseline in both groups during recovery, not showing withdrawal.
Conclusions:
- Prolonged post-faint hypotension (PPFH) is not mediated by exaggerated peripheral vasodilation or sympathetic withdrawal.
- Delayed recovery of cardiac output, likely influenced by increased vagal outflow, is a more probable cause of PPFH.
- These findings highlight the complex autonomic regulation following syncope and identify potential targets for future research.
Related Concept Videos
01:25Cardiopulmonary Resuscitation IV: Pharmacological Management
Pharmacologic intervention is crucial in treating cardiac arrest patients during ACLS or Advanced Cardiovascular Life Support. The ACLS algorithms guide the administration of specific drugs based on the patient's cardiac arrest rhythm, which includes pulseless ventricular tachycardia (VT), ventricular fibrillation (VF), asystole, and pulseless electrical activity (PEA).EpinephrineIndication: Epinephrine is the first-line drug for all cardiac arrest rhythms.Mechanism of Action: Epinephrine...
01:30Alterations in Blood Pressure
Alterations in blood pressure, such as hypertension (high blood pressure) and hypotension (low blood pressure), significantly affect human health. Understanding these conditions' classifications, causes, and symptoms is essential for effective management and treatment.
Hypertension (High blood pressure)
Hypertension occurs when blood pressure readings consistently exceed the normal range. It is diagnosed when systolic blood pressure (the top number, indicating pressure while the heart beats)...
Hypertension (High blood pressure)
Hypertension occurs when blood pressure readings consistently exceed the normal range. It is diagnosed when systolic blood pressure (the top number, indicating pressure while the heart beats)...
01:26Cardiac Catheterization IV: Nursing Management
Nursing responsibilities before cardiac catheterization include:Assess for allergies and establish baseline health status.Before cardiac catheterization, assess the patient for allergies to contrast dye. Perform a comprehensive baseline assessment, including vital signs, heart and breath sounds, and a neurovascular assessment of the extremities, noting distal pulses, skin color, and temperature. Instruct the patient to fast for 8-12 hours before the procedure. Evaluate baseline laboratory...
01:28Special considerations while measuring blood pressure
When assessing blood pressure (BP), healthcare professionals must consider various factors and potential unexpected outcomes to ensure accurate readings and provide proper patient care. Adhering to these guidelines is essential to achieving the most reliable results.
Monitoring Both Arms:
Monitoring BP in both arms during the initial assessment is advisable, as the systolic value may differ by five to ten mm Hg between arms. For subsequent BP assessments, use the arm with the higher reading.
Monitoring Both Arms:
Monitoring BP in both arms during the initial assessment is advisable, as the systolic value may differ by five to ten mm Hg between arms. For subsequent BP assessments, use the arm with the higher reading.
01:22Stages of General Anesthesia
Various sedation levels offer significant advantages in facilitating procedural interventions for patients undergoing medical or invasive surgical procedures. These levels span from anxiolysis to general anesthesia, providing a spectrum of sedative effects to cater to specific patient needs. Anxiolysis reduces anxiety and is achieved through minimal sedation, enabling patients to remain awake and responsive while feeling more at ease during the procedure. This level can benefit minor...
01:20Angina V: Nursing Management
Angina, a symptom of myocardial ischemia, requires a structured nursing management approach to ensure effective care and prevent complications like myocardial infarction. Comprehensive nursing care involves assessing, diagnosing, planning, implementing interventions, and evaluating outcomes, all tailored to the individual patient's needs.Patient AssessmentNursing assessment begins with a detailed subjective evaluation of symptoms, which typically include chest pain or pressure radiating to the...