Methods of Reperfusion
In modern medical practice, the frequency of post-occlusion reperfusion has significantly increased. Restoring blood flow is applied, among other scenarios, in the acute period of myocardial infarction. All methods are divided into two broad groups:
- Surgical methods: coronary artery bypass grafting (CABG), coronary artery stenting, and balloon angioplasty.
- Medical methods: thrombolysis, vasodilation, and blood cell antiplatelet therapy.
Adaptive Effects of Reperfusion
The positive effect of restoring blood flow aims to preserve and protect the heart muscle. Adaptive effects include:
- Preventing the development of myocardial infarction and reducing its overall size.
- Preventing the formation of dangerous aneurysms in the area previously subjected to ischemia.
- Stimulating connective tissue formation in the aneurysm wall if it has already developed.
- Potentiating the complete recovery of the heart's contractile function.
Pathogenic Effects and the Injury Phenomenon
The initial stage of post-occlusion reperfusion can lead to negative consequences and cardiac dysfunction, known as the "reperfusion injury" phenomenon.
At this point, severe reperfusion arrhythmias occur, up to ventricular fibrillation, carrying a risk of mortality. Destabilization of central and tissue-level hemodynamics and a marked imbalance in biochemical and electrophysiological parameters are also observed. Consequently, early injury to the reperfused area may be prolonged and intensified.
Mechanisms of Arrhythmias and Cardiac Properties
Dangerous arrhythmias during reperfusion are based on disorders of three of the four fundamental properties of the heart:
- Automaticity — the ability to spontaneously generate impulses.
- Conductivity.
- Excitability — the ability of cells to receive an electrical impulse and respond by generating an action potential (AP).
Note: Clinicians most frequently encounter combined disorders of these properties. Meanwhile, contractility disorders (the fourth property) do not cause rhythm disturbances, but rather serve as a direct cause of heart or myocardial failure.