Hypertension, ischaemic heart disease and cardiac failure Flashcards
What is hypertension?
High blood pressure
Pulmonary= low pressure circulation, systemic= high (common)
Can occur in either or both circulations
What is the equation used for blood pressure?
BP= cardiac output x peripheral resistance
What are the classifications of systemic hypertension?
Primary vs secondary (based on cause)
Benign vs malignant (based on clinical presentation)
What is systematic hypertension?
Sustained resting blood pressure above certain level
140/90 mmHg (depends)
Diastolic pressure determines severity
What are the percentages of classification by cause?
Primary= 90% (idiopathic= unknown)
Secondary= 10%
-90% due to renal disease
-10% other causes especially endocrine disease
What are the risk factors for systemic hypertension?
Genetic susceptibility
High salt intake
Chronic stress (excessive sympathetic activity)
Abnormalities in renin/ angiotensin- aldosterone
Obesity
Diabetes mellitus
(careful clinical assessment- test the urine!)
Causes of secondary systemic hypertension
Renal disease- chronic renal failure polycystic kidneys
Endocrine- pituitary (ACTH), adrenal cortex= glucocorticoid, mineralocorticoid, adrenal medulla= catecholamines
Drug treatment= steroids
Coarctation of aorta
What is the difference between benign and malignant hypertension?
Benign= slow changes in vessels and heart with chronic and end-organ dysfunction Malignant= rapid changes in vessels with acute end-organ dysfunction/ blood pressure tends to be higher
Where are-organ effects acting on?
Heart
Kidney
Brain
Vessels (including retina)
What are the end-organ effects of the heart?
Left ventricular hypertrophy- fibrosis, arrhythmias
Coronary artery atheroma
Ischaemic heart disease
Cardiac failure
What are the end-organ effects of the kidneys?
Nephrosclerosis (drop- out of nephrons = vascular narrowing, proteinuria, chronic renal failure)
Malignant hypertension is associated with acute renal failure
What vascular changes lead to benign and malignant hypertension?
Benign= acceleration of atherosclerosis, intimal proliferation and hyalinisation f arteries and arterioles
Malignant hypertension= fibrinoid necrosis
Describe ischaemic heart disease
Blood supply to the heart is insufficient for its metabolic demands
Deficient supply- coronary heart disease, reduced coronary artery perfusion (shock, severe aortic valve stenosis)
Excessive demand- pressure overload (hypertension, valve disease)/ volume overload (valve disease)
What is coronary artery disease?
Coronary blood flow is normally independent of aortic pressure, initial response to narrowing is compensation
over 75% occlusion leads to ischaemia
What are the causes of coronary artery disease?
Atheromatous coronary artery disease= progressive stenosis, haemorrhage into a plaque, thrombosis
Emboli (inflamed aortic valve- endocarditis)
Vasculitis
What is a myocardial infarction?
An area of necrosis of heart muscle resulting from reduction (usually sudden) in coronary blood supply