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Related Concept Videos

Dysrhythmias V: Evaluating Dysrhythmias01:30

Dysrhythmias V: Evaluating Dysrhythmias

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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...
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The heart's primary function is to pump blood throughout the body, maintaining a balance between blood sent out (cardiac output) and blood returning (venous return). If this balance is disrupted, it can result in congestive heart failure (CHF), a severe condition where the heart becomes an inefficient pump, leading to inadequate blood circulation.
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Pulse rhythm01:30

Pulse rhythm

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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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Mechanism of Cardiac Arrhythmias01:28

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Arrhythmias are irregular heart rhythms occurring when the heart's electrical impulses become abnormal. These disturbances can lead to various symptoms, depending on their severity and the underlying cause. Some common factors contributing to arrhythmias include hypoxia, ischemia, electrolyte imbalances, excessive catecholamine exposure, drug toxicity, and muscle overstretching. Arrhythmias can be classified into two main types based on the rate and site of origin of abnormal heart rhythms.
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The Cardiac Cycle

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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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Cardiac Alternans: From Bedside to Bench and Back.

Zhilin Qu1, James N Weiss1

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Circulation Research
|January 5, 2023
PubMed
Summary
This summary is machine-generated.

Cardiac alternans, instabilities in heart electrical and calcium systems, often precede fatal arrhythmias. This review details alternans mechanisms, linking them to heart rhythm disorders and patient electrocardiographic signatures.

Keywords:
Brugada syndromeatrial fibrillationcardiovascular diseaseslong QT syndromemyocardial ischemiatorsades de pointesventricular fibrillation

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Area of Science:

  • Cardiology
  • Computational Biology
  • Physiology

Background:

  • Cardiac alternans are dynamical instabilities in the heart's electrical and calcium cycling systems.
  • Alternans often precede life-threatening ventricular arrhythmias and sudden cardiac death.
  • Understanding alternans is crucial for predicting and preventing cardiac events.

Purpose of the Study:

  • To provide a holistic overview of cardiac alternans.
  • To integrate clinical, theoretical, and experimental findings on alternans.
  • To elucidate the mechanisms, arrhythmic manifestations, and electrocardiographic signatures of alternans.

Main Methods:

  • Review of existing clinical observations, theoretical models, and experimental data.
  • Summarization of demonstrated cellular and tissue-level alternans mechanisms (3 voltage-driven, 2 calcium-driven).
  • Analysis of experimental and simulation results linking alternans to arrhythmogenesis and electrocardiographic characteristics.

Main Results:

  • Detailed description of multiple voltage- and calcium-driven alternans mechanisms.
  • Demonstration of the relevance of these mechanisms to arrhythmogenesis in various disease states.
  • Correlation of alternans mechanisms with specific electrocardiographic patterns observed in patients.

Conclusions:

  • Cardiac alternans are both predictors and causal mechanisms of lethal ventricular and atrial arrhythmias.
  • Alternans are implicated in a broad spectrum of arrhythmia mechanisms, particularly functional reentry.
  • While crucial for functional reentry, alternans play a lesser role in anatomic reentry and focal arrhythmias.