3- Chronic Ischemic Heart disease- progressive heart failure due to ischemic myocardial damage- Cause severe fixed coronary obstruction (AS- Inmost cases there is a history of MI
-
seen in elderly - CF CHF
- diagnosis depends on exclusion of other CHF causes- death can result from 1- progressive CHF
2- superimposed
acute MI- arrhythmia 4- Sudden cardiac death (SCD)- unexpected death from cardiac causes either
-
without symptoms or - within 24 hours of symptom onset- Cause - severe atherosclerosis with occlusive thrombosis- leading to lethal arrhythmia ( ventricular arrhythmia)
Myocardial Response to Ischemia:- if ischemia lasts for less than 2 min loss of contractility- if ischemia lasts between 2 - 10 minutes causes reversible injury to myocytes.
- if ischemia lasts 20-40 minutes causes irreversible injury to myocytes.
Reperfusion:- If myocardial blood flow is restored before 20-40 minutes myocyte viability maybe preserved- reperfusion: can be achieved by
1- thrombolytic therapy (streptokinase)
2- angioplasty- Reperfusion can cause injury and changes
in necrotic myocardium 1- contraction band necrosis in damaged myocytes (arrowed)
* are eosinophilic transverse bands
* composed of hypercontracted sarcomeres
* due to exaggerated contraction of myofibrils in dead cells due to influx of Ca- hemorrhage (injured vessel is leaky after flow is restored)
