week 7 - disorders of cardio part 2 Flashcards
What are the 3 layers of the heart wall?
epicardium
myocardium
endocardium
What is the pericardium?
It is a sac that encloses the heart
What is the epicardium?
Part of the pericardium.
Outer layer of the heart.
Keeps heart in position, prevents friction.
Thin layer.
What is the myocardium?
The middle layer, most thickest.
Contractile layer composed of cardiac muscle
What is the endocardium?
Innermost layer of the heart wall.
A thin layer.
Lines the chambers and regulates myocardial function
What is pericarditis?
It is a disorder of the pericardium caused by inflammation.
The inflammation can be caused by:
Tumour
Autoimmune conditions
Viruses/bacteria
Uraemia
Some drugs
How does pericarditis affect cardiac function?
The inflammation causes friction during contraction of the heart, chest pain and scratch rubbing sound.
This increases the effort required by the heart leading to symptoms like shortness of breath, coughing and fatigue.
What can the coughing symptom of pericarditis lead to and what is it caused by?
The coughing in pericarditis is caused by venous hypertension leading to pulmonary oedema
What is cardiac tamponade?
The accumulation of fluid or blood between the 2 layers of the pericardium – can be caused by viral, bacterial, cancer, injury etc
All this fluid puts pressure on the heart so the heart can’t pump blood properly.
The heart cannot expand fully so doesn’t full fully with blood
What can cardiac tamponade lead to?
It can lead to reduced tissue perfusion – a lack of oxygenated blood flowing to areas of the body
Leads to faster heartbeat, reduced blood pressure, accelerated breathing, paradoxical pulse.
What is paradoxical pulse?
Pulse weakens when breathing in and strengthens when breathing out due to changes in intrathoracic pressure.
What is endocarditis?
Disorders of the endocardium caused by inflammation of the endocardium.
Onset takes weeks/months
What are the symptoms of endocarditis?
Symptoms are due to embolisation:
stroke, ischaemia - reduced blood supply
limb pain
abdominal pain
Can lead to:
Malaise
Anorexia
Fatigue
Low grade fever
Night sweats
Headache
Backache
Heart murmur
It can lead to heart failure due to decreased CO.
What is infective endocarditis?
The colonisation of the endocardium by microbes
What can infective endocarditis cause?
It can cause structural abnormality, leading to turbulent fast blood flow leading to platelet thrombi forming and dissolving – Virchow’s Triad
How can you tell whether an organism (like a microbe) will cause infective endocarditis?
By determining the organism’s affinity of binding to platelets/thrombi due to endocardial structure. – some examples maybe
What is cardiac diastole?
The filling of the ventricles with blood
What is cardiac systole?
This is where the ventricles pump out most of the blood (60%)
What are some causes of the impaired contractile ability of the heart?
Infections
Tumours
Ischaemia
Drugs
Toxins
Commective tissue diseases
Endocrine diseases
What is hypertrophic cardiomyopathy?
When the size of an organ/tissue increases in size, due to enlargement of cells NOT by multiplication of cell.
It obstructs blood flow from the left ventricle
Has genetic causes – 50% autosomal dominant
Can result in sudden death under stressful conditions – like competitive sport
CARDIOMYOP MECHANISMS
What is dilated cardiomyopathy?
It is cardiac enlargement which causes reduced contraction of the ventrucles.
Can result in heart failure, thromboembolism etc
Dilated cardiomyopathy mechanism
What is restrictive caardiomyopathy?
Very rare.
The enlargement restricts the heart from stretching and filling with blood due to stiffened heart walls. Can cause heart failure as blood flow becomes reduced
What is obliterative cardiomyopathy?
It is where the apices of the ventricles become thickened and fibrotic, decreasing volume of blood.
What do all cardiomyopathies do?
They all reduce contractility of the heart, thereby reducing ability to pump the blood
What is a cardiac arrhythmia?
An alteration in the heart rate or heart rhythm
It can decrease the efficiency of the heart’s pumping ability
Types such as brady/tachycardia
What is coronary artery disease?
It is where the blood supply to the heart muscle is blocked. Can cause a heart attack.
Can also cause heart failiure.
What is chronic heart failure?
“A complex clinical syndrome characterized by abnormalities of left ventricle function and neurohormonal regulation which are accompanied by effort intolerance, fluid retention and reduced longevity.”
What is the Frank Starling mechanism?
As the heart wall stretches it will contract more strongly.
What factors can affect cardiac output?
Preload – the filling of the heart during diastole
Contractility – The strength of the muscular contraction
Afterload – resistance to the pumping of the blood into the major arteries.
What factors can predispose you to suffer from heart failure?
Coronary Heart Disease.
Obesity
Diabetes
Smoking
Hypertension – high blood pressure
What are the causes of heart failure?
Myocardial Infarction
Valve defects
Coronary Artery Disease
Congenital heart defects
Hypertension
What are the key symptoms associated with heart failure?
Dyspnea
Cyanosis
Pleural Effusion
Hepatomegaly
Edema in hands/legs
Decreased urine output
What is systolic dysfunction?
This is where the heart doesn’t contract normally, so the ventricles fill with the normal amount of blood but PUMP OUT less blood than normal.
Enlarged ventricles
Can impair heart muscle because it can reduce blood flow to large areas of the heart muscle.
A common cause is coronary artery disease.
What is diastolic dysfunction?
This is where the stiff ventricles fill with LESS blood than normal but still pump out the normal amount of blood (60%)
Can be caused by inadequately treated high blood pressure
What are the symptoms of left sided heart failure?
Congestion of lungs leads to shortness of breath on exertion, leading to fatigue
What are the symptoms of right sided heart failure?
Causes congestion of the peripheral tissues leading to peripheral oedema, nocturia, ascites, hepatomegaly
What are the other factors that can worsen heart failure?
illness like pneumonia
myocardial infarction
anaemia
hyperthyroidism
because all these put strain on the heart muscle so it can’t cope
What does left sided heart failure cause?
It causes back up of blood into the pulmonary circulation resulting in pulmonary oedema - fluid in the lungs
The right ventricle may enlarge bc of extra work of pumping blood into the lungs
What dies right sided heart failure cause?
Causes back up of blood into the systematic circulation
What is mitral stenosis?
It causes blood to back up to the lungs then to the right side of the heart causing heart failure
left sided heart failure mechanusms
What is shock?
A serious condition where insufficient blood flow reaches the tissues
Can cause hypoxia, ischaemia, cardiac arrest as there is a loss of oxygen and nutrient supply to the tissues
What are the 4 types of shock?
Hypovolaemic
Distributive
Cardiogenic
Obstructive
What is hypovolaemic shock and what is it caused by?
It is when there is a low circulating volume around the body due to the loss of blood/plasma from burns, dehydration and bleeding
What is distributive shock and what is it caused by?
It is when there is effectively low circulating volume caused by a reaction to infection, allergen or damage to spinal cord
What is obstructive shock and what is it caused by?
It is shock caused by the block of blood flow via thrombosis, embolism etc
What is cardiogenic shock and what is it caused by?
It is shock caused by failure of the heart to pump effectively due to damage of the heart muscle, arrhythmia etc
What is the initial time course with medical shock?
- Negative feedback attempts to reverse the condition
- Baroreceptors detect hypertension
- Nor/adrenaline released
- Vasoconstriction occurs to increase BP
- Blood is diverted to essential organs
What is the chemical time course with medical shock?
- Hypofusional state
- Lack of oxygen causes a failure to make ATP
- Anaerobic respiration occurs due to lack of oxygen spots there is a build up of lactic and pyruvic acid
- Metabolic acidosis - a buildup of acid in the body
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