左心室壁的表心激活延长了QT间隔和复极化的跨心室分散:对双心室节奏的含义
Jeffrey M Fish1, José M Di Diego, Vladislav Nesterenko
1Masonic Medical Research Laboratory, Utica, NY 13501-1787, USA.
Circulation
|April 14, 2004
概括
左心室的表心节奏延长了QT间隔,并增加了复极化分散,为危险的心律失常创造了基质. 这项细胞研究解释了表心激活逆转背后的节律失常机制.
科学领域:
- 心脏病学 心脏病学
- 电子生理学 电子生理学
- 心脏节律失常症 心脏节律失常症
背景情况:
- 众所周知,左心室 (LV) 的心周节奏延长了QT间隔,并增加了Torsade de pointes心律失常的风险.
- 由于LV激活方向逆转,导致QT延长和心律失常的细胞机制需要进一步研究.
研究的目的:
- 在LV激活方向逆转时,研究QT延长和心律失常的细胞基础.
- 阐明表心与内心节奏对跨心 repolarization 和导电的影响.
主要方法:
- 从犬类LV准备剂同时记录跨膜心电图 (ECG) 和跨膜动作潜力.
- 在动脉 perfused 条件下从表心,M 细胞和内心细胞进行测量.
- 实验与并没有快速激活延迟整流器电流阻塞 (例如,E-4031,cisapride) 进行.
主要成果:
- 将节奏从内心转移到上心显著增加了QT间隔和反极化 (TDR) 的跨壁分散.
- 在M细胞和心表细胞之间的导电时间随着心表节奏的增加而增加.
- 阻塞剂进一步增强了TDR放大,在这些条件下,Torsade de pointes节律失常在表心节奏过程中是可诱导的.
结论:
- 反向LV激活,如在双腹节奏中所见,显著增加了QT和TDR,这是由于心表细胞和M细胞之间的差异性再极化.
- 提升的TDR创造了一个电生理基质,有利于在延长的QT间隔的背景下导致torsade de pointes心律失常.
相关概念视频
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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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The Process
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 empty blood into the...
01:19Electrophysiology of Normal Cardiac Rhythm
The normal cardiac rhythm is a synchronized electrical activity that facilitates the regular and coordinated contraction of the heart muscle. This process is essential for efficient blood circulation throughout the body. The fundamental elements involved in establishing and maintaining this rhythm include the unique electrical properties of cardiac muscle cells, the sinoatrial (SA) node's pacemaker function, the specialized conducting system, and the ionic mechanisms underlying each phase of...
01:16Chambers of the Heart
The human heart is a complex organ made up of four chambers: the right and left atria and the right and left ventricles. These internal chambers are separated by partitions known as the interatrial and interventricular septa. The exterior of the heart features a groove known as the coronary sulcus that demarcates the atria from the ventricles, while the anterior and posterior interventricular sulci distinguish between the two ventricles.
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Deoxygenated blood from the body is received in the right...
01:29Disturbances 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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01:30Cardiac Action Potential
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Ionic Basis of Cardiac Action Potentials
01:18Dysrhythmias IV: Characteristics of Bradyarrhythmias
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