Sudden Cardiac Death and Sleep Apnea
Obstructive sleep apnea (OSA) raises the risk of sudden cardiac death (SCD) by 300–400% depending on the severity of OSA. Increase temporal dispersion in myocardial depolarization has been shown to enhance the genesis of malignant arrhythmias that in turn raise sudden death risk.
In a study of 10,000 adults who participated in a sleep study, the risk of sudden cardiac death was almost twice as high in patients who stopped breathing more than 20 times an hour during sleep.
In people with obstructive sleep apnea, sudden cardiac death is more likely to occur between the hours of 10pm and 6am.
Sudden cardiac death accounts for 450,000 deaths annually.
Obstructive sleep apnea applies profound oxidative stress to the cardiovascular system. Repetitive night time hypoxemia (an abnormally low level of oxygen in the blood) and arousals leads to:
Ischemia reperfusion – tissue damage caused when blood supply returns to the tissue after a period of ischemia or lack of oxygen (anoxia, hypoxia). The absence of oxygen and nutrients from blood during the ischemic period creates a condition in which the restoration of circulation results in inflammation and oxidative damage through the induction of oxidative stress rather than restoration of normal function.
Cellular degeneration – Nonlethal injury to a cell. It is manifested as some irregularity of biochemical function, a recognizable structural change, or a combined biochemical and structural abnormality. Degeneration is reversible but may progress to cellular death if the injury persists. When it is associated with abnormal cell function, cell degeneration may also cause clinical disease.
Apoptosis – A form of cell death in which a programmed sequence of events leads to the elimination of cells without releasing harmful substances into the surrounding area.
Cardiac remodeling – Ventricular remodeling (or cardiac remodeling) refers to the changes in size, shape, structure, and function of the heart. This can happen as a result of exercise (physiological remodeling) or after injury to the heart muscle (pathological remodeling).
Reentrant arrhythmias – a type of tachycardia occurring in the ventricle where the cause of the arrhythmia is due to the electric signal not finishing the normal circuit, but rather an alternative circuit looping back upon itself.