New ischemic syndromes Yeni iskemik sendromlar
SENDROM, cilt.17, sa.12, ss.64-70, 2005 (Scopus)
- Yayın Türü: Makale / Derleme
- Cilt numarası: 17 Sayı: 12
- Basım Tarihi: 2005
- Dergi Adı: SENDROM
- Derginin Tarandığı İndeksler: Scopus
- Sayfa Sayıları: ss.64-70
- Sağlık Bilimleri Üniversitesi Adresli: Evet
Özet
Reperfusion injury refers to a syndrome of related conditions that may follow reperfusion of the ischemic myocardium. For example, thrombolytic reperfusion may bring in its wake arrhythmias, stunning, and no-reflow. Whether reperfusion can actually accelerate cell death remains controversial. Mechanisms for reperfusion damage are twofold: cytosolic calcium over-load and formation of free radicals. Other important events include endothelial dysfunction, reintroduction of neutrophils into the ischemic area, and microvascular damage. The new ischemic syndromes include the novel aspects of ischemia, such as stunning, hibernation, and preconditioning, in contrast to the classic conditions such as angina pectoris, unstable angina, and infarction. Stunning is the delayed recovery of mechanical function after reperfusion. It varies in duration from minutes, hours to days, and can experimentally be averted by a number of interventions, including Na+/Ca+ exchange inhibition and calcium antagonists, as well as by a variety of free radical scavengers. Hibernation occurs when the ventricle contracts poorly in the presence of severe coronary artery disease, but wakes up after revascularization by coronary artery surgery. Two current hypothesises are downgrading of myocardial energy requirements and repetitive stunning. Preconditioning is the protective state that lessens the severity of ischemic reperfusion when it follows one or more brief episodes of preceding ischemia. In clinical conditions, ischemia, stunning, hibernation, necrosis, and normal myocardium may coexist.