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Related Concept Videos

Regulation of Heart Rates01:31

Regulation of Heart Rates

The regulation of heart rate is a complex process controlled by the autonomic nervous system (ANS), hormonal influences, and intrinsic cardiac mechanisms. The ANS has two main components: the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS).
The SNS increases heart rate through the release of norepinephrine and epinephrine, which act on beta-1 adrenergic receptors in the heart. This action increases the rate of depolarization in the sinoatrial (SA) node, the heart's...
Dysrhythmias IV: Characteristics of Bradyarrhythmias01:18

Dysrhythmias IV: Characteristics of Bradyarrhythmias

Bradyarrhythmias are cardiac rhythm disorders characterized by a slower-than-normal heart rate, typically defined as fewer than 60 beats per minute. Some of which are discussed here:Sinus BradycardiaSinus bradycardia presents a heart rate lower than 60 beats per minute, with a regular rhythm originating from the SA node. The ECG typically shows normal P waves preceding each QRS complex, a normal PR interval (0.12 to 0.20 seconds), and a normal QRS duration (0.06 to 0.10 seconds).First-Degree AV...
Dysrhythmias V: Evaluating Dysrhythmias01:30

Dysrhythmias V: Evaluating Dysrhythmias

Dysrhythmias, also known as arrhythmias, are disturbances in the heart's rhythm that range from benign to life-threatening. A thorough evaluation is crucial for appropriate management and involves a comprehensive medical history, physical examination, and various diagnostic tests.Medical HistorySymptoms: Collect detailed information on palpitations, dizziness, syncope, chest pain, and fatigue. Note their onset, frequency, and triggers.Previous Cardiac Issues: Document any history of heart...
Factors Influencing Heart Rate01:30

Factors Influencing Heart Rate

The heart rate, or pulse rate, is a vital indicator of cardiovascular health. It reflects the number of times the heart beats per minute. Various physiological and environmental factors influence heart rate, increasing or decreasing cardiac output. Understanding these factors is crucial for assessing heart function and identifying potential health issues.
Let us explore the significant factors affecting heart rate, including age, body temperature, posture, acute pain, chemical influences,...
Dysrhythmias III: Characteristics of Dysrhythmias01:29

Dysrhythmias III: Characteristics of Dysrhythmias

Dysrhythmias, also known as arrhythmias, are irregular heart rhythms that result from abnormal electrical activity in the heart, affecting its ability to circulate blood efficiently. Tachyarrhythmias, a subset of dysrhythmias, are characterized by abnormally fast heart rates exceeding 100 beats per minute. Here are some types of tachyarrhythmias with their distinct ECG features:Sinus Tachycardia:Sinus tachycardia presents a regular heart rhythm with an increased rate of 101-180 beats per minute.
Disturbances in Heart Rhythm01:29

Disturbances in Heart Rhythm

Arrhythmia or dysrhythmia refers to an abnormal heart rhythm caused by a defect in the heart's conduction system. It can cause the heart to beat irregularly, too quickly, or too slowly, leading to symptoms like chest pain, shortness of breath, and fainting. Factors such as stress, caffeine, alcohol, nicotine, cocaine, certain drugs, congenital defects, diseases, and electrolyte abnormalities can trigger arrhythmias.
Arrhythmias are categorized by their speed, rhythm, and origin. A slow heart...

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Autonomic Function Following Concussion in Youth Athletes: An Exploration of Heart Rate Variability Using 24-hour Recording Methodology
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Heart rate variability in neurally mediated reflex syncope.

Uğur Arslan1, Murat Ozdemir, Sedat Türkoğlu

  • 1Gazi University School of Medicine, Department of Cardiology, Ankara, Turkey. ugurarslan5@yahoo.com

Acta Cardiologica
|January 9, 2007
PubMed
Summary

Patients with neurally mediated reflex syncope show altered heart rate variability (HRV) parameters. Higher HRV indicates increased parasympathetic activity, correlating with positive head-upright tilt test (HUTT) results.

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Area of Science:

  • Cardiology
  • Autonomic Nervous System Function

Background:

  • Neurally mediated reflex syncope (NMRS) is a common cause of transient loss of consciousness.
  • Heart rate variability (HRV) reflects autonomic nervous system activity.
  • Understanding HRV in syncope can aid diagnosis and management.

Purpose of the Study:

  • To investigate heart rate variability (HRV) parameters in patients diagnosed with neurally mediated reflex syncope (NMRS).
  • To correlate HRV findings with head-upright tilt test (HUTT) results in syncope patients.

Main Methods:

  • Thirty-three patients with a history of vasovagal syncope (VVS) underwent 24-hour Holter monitoring for HRV analysis.
  • Patients were categorized based on positive (HUTT+) or negative (HUTT-) results from head-upright tilt testing.
  • A control group of 16 healthy individuals without syncope was included for comparison.

Main Results:

  • HUTT-positive syncopal patients exhibited higher time-domain HRV parameters compared to HUTT-negative responders.
  • While not statistically significant, HUTT-positive patients showed trends towards higher NN50, pNN50, RMSSD, and SDNNi values versus controls.
  • HUTT-negative VVS patients displayed lower SDNN and SDANN values than the control group.

Conclusions:

  • Elevated heart rate variability (HRV) parameters suggest increased parasympathetic tone in syncope patients.
  • Increased parasympathetic activity is associated with a higher likelihood of positive HUTT results in individuals with syncope and no underlying heart disease.