Related Experiment Video

Updated: Oct 13, 2026

Optimization of Transesophageal Atrial Pacing to Assess Atrial Fibrillation Susceptibility in Mice
08:05

Optimization of Transesophageal Atrial Pacing to Assess Atrial Fibrillation Susceptibility in Mice

Published on: June 29, 2022

Abnormal coronary flow profiles at rest and during rapid atrial pacing in patients with hypertrophic cardiomyopathy

A Kawamura1, T Fujii, T Miura

  • 1The Second Department of Internal Medicine, Yamaguchi University School of Medicine, Ube, Japan.

Japanese Circulation Journal
|August 16, 2000
PubMed

Insights

Hypertrophic cardiomyopathy (HCM) patients show impaired coronary flow velocity, particularly during rapid heart rates. This suggests abnormal diastolic function contributes to myocardial ischemia in HCM.

Area of Science:

  • Cardiology
  • Cardiovascular Physiology

Background:

  • Hypertrophic cardiomyopathy (HCM) is a genetic heart condition characterized by thickening of the heart muscle.
  • The mechanisms underlying myocardial ischemia in HCM are not fully understood.
  • Assessing coronary blood flow is crucial for understanding cardiac function in HCM.

Purpose of the Study:

  • To investigate the coronary flow velocity patterns in the left anterior descending coronary artery (LAD) in patients with HCM.
  • To elucidate the relationship between heart rate, coronary flow dynamics, and myocardial ischemia in HCM.
  • To compare coronary flow velocity in HCM patients with healthy controls.

Main Methods:

  • Coronary flow velocity in the LAD was measured using a Doppler guide wire in 11 HCM patients and 8 controls.
  • Measurements were taken at rest and during rapid atrial pacing to simulate increased heart rates.
  • Key parameters calculated included average peak velocity (APV), percent increase of APV (%APV), systolic velocity (Vs), and diastolic velocity (Vd).

Main Results:

  • In HCM patients, APV peaked at 90 beats/min, unlike controls where it increased up to 130 beats/min.
  • Systolic flow velocity (Vs) decreased in HCM during pacing, while it increased in controls.
  • Diastolic flow velocity (Vd) in HCM peaked at 90 beats/min, contrasting with controls' continuous increase.
  • The acceleration rate of early diastolic flow was significantly lower in HCM patients.

Conclusions:

  • HCM patients exhibit abnormal coronary flow velocity responses to increased heart rates.
  • Reduced acceleration of early diastolic flow velocity in the LAD may contribute to diastolic dysfunction and ischemia in HCM.
  • These findings highlight impaired coronary microvascular function as a potential mechanism for myocardial ischemia in HCM.

Related Concept Videos

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.
Cardiomyopathy III: Hypertrophic Cardiomyopathy01:29

Cardiomyopathy III: Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy, or HCM, is an autosomal dominant genetic disorder characterized by asymmetric left ventricular hypertrophy without ventricular dilation. It is more common in men and is typically diagnosed in young, athletic adults.EtiologyHCM is primarily genetic and is caused by mutations in genes encoding sarcomeric proteins. Researchers have identified over 1400 mutations across at least 11 different genes. Among these, the most frequently occurring mutations are found in the...
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...
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...
ECG Interpretation of Arrhythmias II: Atrial, Junctional and Ventricular Arrhythmias01:25

ECG Interpretation of Arrhythmias II: Atrial, Junctional and Ventricular Arrhythmias

Arrhythmia is a condition characterized by an irregular heart rhythm, with ECG changes that differ based on its origin and nature. The types of arrhythmias discussed below include atrial, junctional, and ventricular arrhythmias.Atrial ArrhythmiasPremature Atrial Complexes (PACs): PACs are early atrial beats caused by stress, caffeine, alcohol, electrolyte imbalances, hypoxia, hyperthyroidism, or certain medications (e.g., bronchodilators and decongestants). The ECG shows early P waves with an...
Mechanism of Cardiac Arrhythmias01:28

Mechanism of Cardiac Arrhythmias

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.