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Related Concept Videos

The Cardiac Cycle01:13

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The heart beats rhythmically in a sequence called the cardiac cycle—a rapid coordination of contraction (systole) and relaxation (diastole).
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Electrical signals—sent from the sinoatrial (SA) node in the right atrial wall to the atrioventricular (AV) node between the right atrium and right ventricle—cause both atria to simultaneously contract. When the signal reaches the AV node, it pauses for approximately a tenth of a second, allowing the atria to contract and...
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Pulse rhythm01:30

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Pulse rhythm refers to the pattern of pulsations within specific intervals, offering valuable insights into the regularity or irregularity of the heart's beats as observed through the pattern of pulsation within specific intervals. A regular pulse exhibits a consistent heart rate with uniform waveforms and pulsation force, variations of which can be classified as normal, weak, or bounding.
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The cardiac cycle refers to the sequence of events that occur in the heart from the beginning of one heartbeat to the next. It's characterized by alternating periods of contraction (systole) and relaxation (diastole) of the heart muscles.
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The electrical signals recorded on an electrocardiogram (ECG) occur before the mechanical processes of contraction and relaxation during the cardiac cycle.
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The cardiac cycle describes the events from one heartbeat to the next. It includes three main phases: diastole, atrial systole, and ventricular systole, all driven by changes in chamber pressures and the function of heart valves.
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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...
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Variation in parasystolic cycle length.

Chikako Ono1, Terunao Ashida, Takao Sugiyama

  • 1Division of Cardiovascular Disease, The Institute for Adult Diseases Asahi Life Foundation, Tokyo, Japan.

International Heart Journal
|February 16, 2006
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Summary

This study investigated parasystole, a heart rhythm disorder. Pure parasystole cycle length remained stable during prolonged monitoring, unlike sinus rhythm, showing distinct responses to exercise and deep breathing.

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Area of Science:

  • Cardiology
  • Electrophysiology

Background:

  • Parasystole is a cardiac arrhythmia characterized by ventricular premature contractions (VPCs).
  • Pure parasystole, defined by consecutive VPCs without intervening sinus beats, presents unique electrophysiological characteristics.

Observation:

  • Electrocardiographic monitoring over several years revealed irregular variations in parasystolic cycle length.
  • Holter monitoring over 3 hours showed a stable parasystolic cycle length of approximately 1,300 ms.
  • Parasystolic cycle length showed distinct responses to physiological stressors compared to sinus cycle length.

Findings:

  • Parasystolic cycle length demonstrated relative stability during 3-hour Holter monitoring.
  • Exercise testing resulted in a slight prolongation of parasystolic cycle length, contrasting with sinus cycle shortening.
  • Deep breathing tests indicated no significant change in parasystolic cycle length between inspiration and expiration, unlike sinus cycle variations.

Implications:

  • The findings suggest that parasystole exhibits distinct autonomic modulation compared to normal sinus rhythm.
  • Understanding these differences is crucial for diagnosing and managing cardiac arrhythmias.
  • Further research into the autonomic control of parasystole may reveal new therapeutic targets.