Добавил:
Upload Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз: Предмет: Файл:
pathohysiology my help.doc
Скачиваний:
1
Добавлен:
01.07.2025
Размер:
569.34 Кб
Скачать

66.Heart failure myocardial form.

It is developed as a result of myocardium primary injury.

Reasons:

    1. arhythmic form– heart conductance system injury;

    2. myocardiopathic form– working myocardium fibers injury;

    3. infections;

    4. intoxications;

    5. hypoxy;

    6. avitaminoses;

    7. coronary circulation disorders;

    8. metabolism some hereditary defects;

Failure can be developed even at normal or decreased load to heart. Ca-independent forms of contractility disorders are delt with K-ions, ATP, regulatory proteins, CNS problems.

Cardioplegy – heart artificial stoppage applied during operations on “dry” heart. Approaches for realizing:

  1. ishemic – aorta is pressed before coronary arteries coming; as after 30 min irreversible changings in cardiomyocytes can appear, this approach is benefit only at short-termed operation;

  2. chemical – high levels of K-ions, acetylcholine and some other substances are introduced in coronary arteries – time for operation lasts 40-60 min;

  3. cool cardioplegy –heart is processed with cool (t=+4°--5°C) physiological solution; time for operation is 60 min.

67. Coronary cirulation disorders. Reperfusion syndrome. Calcium paradox. Oxygen paradox.

Calcium paradox – experimental phenomenon which is developed after Ca-ions putting in Ca-free solution with which heart was perfused before this. Myocardium irreversible injury takes place, ATP and creatinephosphate level is decreased, proteins are released from myocardium (particularly enzymes like myoglobine, cratinekinase), sarcoplasmic reticulum is destroyed. Explaining: glycokalyx external layer of cardiomyocytes is coming away from internal one in Ca-free solution as the result of which sarcolemma permeability to Ca-ions is significantly increased. At following Ca putting in heart its level is increased and Ca-dependent injury is triggered.

Reperfusional syndrome – syndrome occurring as a result of blood circulation restoration in myocardium ishemized locus id est as reperfusion result.

Reasons:

  1. coronary angiospasm stoppage;

  2. thrombus lysis;

  3. blood cells aggregates decomposition;

  4. thromb surgical removal;

  5. ligature putting out.

Clinically the syndrome is characterized by significant intensification of myocardial injury right after coronary circulation restoration, patient’s state is getting worse. Minimal ishemia duration after which reperfusion is possible is 40 min. If 20 min – reperfusion syndrome is not developed – such duration is at stenocardia. Essence of reperfusional syndrome is “oxygen paradox” – if heart is perfused with oxygen-free solution (or O2 amount is low in it) and then after 40 min to change this solution to the one with normal oxygen level than heart disorders caused by hypoxy will not be decreased (on the contrary, they will be strongly increased!!!! – paradox). Reason: peroxidative lipid oxidation activation in myocardium.

Heart ishemic disease – is a disease developed as a result of absolute insufficiency of coronary circulation which is expressed in myocardium injury of different degree.

Clinical forms:

  1. stenocardy – ishemy fit is up to 20 min;

  2. pre-infarction state (intermediate coronary syndrome or myocardium acute focal dystrophy) – ishemy lasts 20-40 min;

  3. myocardial infarction – ishemy fit is 40-60 min; coronary circulation irreversible changings;

  4. cardiosclerosis: diffuse (atherosclerotic) and focal (after-infarction).

Соседние файлы в предмете [НЕСОРТИРОВАННОЕ]