Theme 9: Cardiovascular Pathology I & II Flashcards
What is the definition of ischaemic heart disease?
generic designation for a group of syndromes resulting from myocardial ischaemia
What is myocardial ischaemia?
an imbalance between demand and supply of oxygenated blood to the heart
What is by far the most common cause of ischaemic heart disease?
coronary artery thrombosis
Other than coronary artery thrombosis, what is another cause of ischaemic heart disease?
hypertrophy of cardiac muscle (increases demand and leads to imbalance)
What are the 4 IHD syndromes?
- Myocardial infarction –> Long duration and severe ischaemia causes myocardial death
- Angina pectoris –> ischaemia is less severe and doesn’t cause myocardial death
- Chronic IHD with heart failure
- Sudden cardiac death
How does angina present?
classic central chest pain
what are the 3 types of angina pectoris?
- stable angina - chest pain aggrevated by exercise or increased demand
- prinzmetal angina - due to vasospasms and usually associated with stress
- Unstable angina - cardiac chest pain initiated independant of exertion
Why does chronic IHD cause heart failure?
atherosclerotic changes that narrow the coronary arteries resulting in a longer duration, less severe ischaemia resulting in decreased contractility of cardiac myocytes, resulting in heart failure
Which 3 syndromes make up acute coronary syndrome?
- Myocardial infarction
- Unstable angina
- Sudden cardiac death
What is the biggest killer of both men and women in the UK?
Ischaemic heart disease
What are the risk factors for IHD?
- High BP
- lipid profile abnormalities
- diabetes
- not total cholesterol but HDL and TC:HDL ratio
- smoking
- sedentary lifestyle
Explain the pathogenesis of MI
Myocardial ischaemia is a consequence of reduced blood flow in the coronary arteries in the heart due too:
- fixed vessel narrowing
- abnormal vascular tone as a result of atherosclerosis
- endothelial dysfunction
This leads to an imbalance between myocardial oxygen supply and demand
What is the definition of a myocardial infarction?
- death of cardiac muscle from prolonged ischaemia
- can be transmural or subendocardial
Where does an MI usually begin? Why?
- in the subendocardium
- this is the least perfused area of the ventricular wall
- this then leads to transmural infarction
What is an atheromatous plaque made up of?
- Fibrous cap - smooth muscle cells, macrophages, foam cells, lymphocytes, collagen, elastin, proteoglycans, neovascularization
- Necrotic center - cell debris, cholerstol crystals, foam cells, calcium
- Media
What are the steps leading to an MI?
- Acute plaque changes
- Platelet aggregration
- Thrombus formation
- Occlusion of coronary artery
Explain the appaearance of the myocardium at the start of infarction, up to 6 weeks later
<24 hrs: normal
1-2 days: pale, oedema, myocyte necrosis, neutrophils
3-4 days: yellow with haemorrhagic edge, myocyte necrosis, macrophages
1-3 week: pale, thin, granulation tissue then fibrosis
3-6 week: dense fibrous scar
What are the complications of an MI?
- arrhythmias (either directly or by limited perfusion to the conduction system e.g SA node –> will occur suddenly)
- congestive heart failure
- thromboembolism
- pericarditis
- ventricular aneurysm
- cardiac tamponade (haemopericardium)
- cardiogenic shock
What are the blood markers of IHD?
- Troponins T&I
- raised post MI, pulmonary embolism, heart failure and myocarditis - Creatine kinase
- Myoglobin
- Lactate dehydrogenase isoenzyme 1
- Aspartate transaminase
What is the definition of hypertension?
a sustained diastolic pressure greater than 90 mmHg or sustained systolic pressure greater than 140 mmHg
What are the causes of primary hypertension?
multifactorial:
- genetic - insulin resistance (metabolic syndrome)
- environmental (obesity, alcohol, smoking, stress, Na+ intake)
How do we calculate blood pressure?
BP = cardiac output x peripheral resistance
both these variables are affected by many factors
Explain how the Renin-angiotensin-aldosterone system works
- drop in blood pressure/ fluid volume
- renin released from kidney
- renin converts angiotensinogen (in liver) into angiotensin I
- ACE converts angiotensin I to angiotensin II
- Angiotensin II acts on the adrenal gland to stimulate the release of aldosterone
- Aldosterone acts on the kidneys to stimulate reabsorption of salt and water
- Angiotensin II acts directly on blood vessels, stimulating vasoconstriction
What are the functions of angiotensin II?
- Constricts resistance vessels thereby increasing systemic vascular resistance and arterial pressure
- Stimulates sodium transport (reabsorption) at several renal tubular sites, thereby increasing sodium and water retention by the body
- Acts on the adrenal cortex to release aldosterone, which in turn acts on the kidneys to increase sodium and fluid retention
- Stimulates the release of vasopressin (ADH) from the posterior pituitary, which increases fluid retention by the kidneys
- Stimulates thirst centres within the brain
- Facilitates norepinephrine release from sympathetic nerve endings and inhibits norepinephrine re-uptake by nerve endings, thereby enhancing sympathetic adrenergic function
- Stimulates cardiac hypertrophy and vascular hypertrophy
what are some causes of secondary hypertension?
- Endocrine - cushing syndrome, acromegaly, thyroid disease
- Adrenal - conn’s disease, pheochromocytoma
- Renal - diabetic nephropathy, renal vascular disease, chronic glomerulonephritis
- CVS - aortic coarctation, renal artery stenosis
- Drugs - NSAIDs, oral contraceptives, steroids
What is malignant hypertension?
Bp > 180/120
- clinical signs and symptoms of organ damage develop
- acute hypertensive encephalopathy
- and/or nephropathy
What is hypertensive heart disease?
systemic (left sided) –> hypertrophy of the heart is an adaptive response to pressure overload that can lead to myocardial dilation, congestive heart failure and sudden death
What is the criteria for hypertensive heart disease?
left ventricular concentric hypertrophy and history or pathological evidence for hypertension
What is Cor Pulmonary?
- pulmonary (right sided) hypertensive heart disease
- right ventricular hypertrophy, dilation and potential heart failure secondary to hypertension caused by disorders of the lung or pulmonary vasculature
What are the causes of cor pulmonale?
- Diseases of the pulmonary parenchyma - COPD, cystic fibrosis, bronchiectasis
- Diseases of pulmonary vessels - thromboembolism, arteritis, drugs
- Disorders affecting chest movement - kyphoscoliosis
- Disorders inducing pulmonary arterial compression
What is Pickwikian syndrome
obesity related hypoventilation syndrome
- prevents normal chest movement
- can lead to cor pulmonale
What is an aneurysm?
a localised abnormal dilation of a blood vessel or the wall of a heart
What are the two types of aneurysm?
- True aneurysm - when dilated section is bounded by arterial wall components or the attenuated wall of the heart
- False aneurysm (pseudoaneurysm) - a breach in the vascular wall leading to an extravascular haematoma that communicates freely with the intravascular space