CSIM 1.65: Cardiovascular Disease 4 Flashcards
Define:
1) Hypertension
2) Mild hypertension
3) Moderate hypertension
4) Severe hypertension
5) Malignant hypertension
1) Sustained elevated pressure over 140/90mmHg (or 130/80mmHg with diabetes or renal disease)
2) Diastolic 90-105
3) Diastolic 105-115
4) Diastolic 115-130
5) Diastolic 130+
What possible mechanisms have been proposed to explain essential hypertension?
- Abnormal renin-angiotensin-aldosterone system
- Abnormal sodium homeostasis
- Abnormal sensitivity to catecholamines (adrenaline, noradrenaline)
Which cells make up the juxtaglomerular apparatus?
- Juxtaglomerular cells
- Macula densa cells
- Lacis agranular cells
Describe how ACE inhibitors work
Inhibit angiotensin-converting enzyme, thus inhibiting the conversion of angiotensin 1 to angiotensin 2
Describe how the release of renin is controlled
Juxtaglomerular cells release renin in response to:
• Reduced NaCl in the macular densa (DCT) due to lowered GFR
• Decrease in renal perfusion rate detected directly
• Stimulation of β1 adrenergic receptor
What are the most common causes of secondary hypertension?
- Renal disease
- Adrenal tumours (pheochromocytoma)
- Coarctation of the aorta (narrow aorta)
- Corticosteroid drug therapy
What are the functions of angiotensin 2?
- Upregulate aldosterone in the zona glomerulosa of the adrenal cortex
- Vasoconstricts
What is benign and malignant hypertension?
Benign hypertension - Hypertension which results in chronic organ changes: HEART CHANGES • Left ventricular hypertrophy • Chronic heart failure • Ventricular arrhythmia VASCULAR CHANGES • Atherosclerosis • Cerebral aneurysm and haemorrhage Treatable with long-term drug therapy
Malignant hypertension - Acute, rapidly progressive hypertension >130mmHg
• Blurred vision from papilloedema
• Retinal haemorrhages
• Renal failure and haematuria
• Cerebral haemorrhage/severe headache
Medical emergency
Define an aneurysm
Localised permanent dilatation of a blood vessel
What is a false aneurysm?
A blood-filled space around a blood vessel
• Caused by trauma or atheroma making the artery leaky, resulting in a pulsatile mass
• Not a true aneurysm as the vessel itself is of a normal calibre
IMG 163
What are the types of aneurysm?
- Atherosclerotic
- Dissecting
- Berry
- Capillary micro-aneurysm
- Syphilitic
- Mycotic
- Cardiac
What type of aneurysm is an abdominal aortic aneurysm an example of? What is the clinical course of this condition after presentation?
What are the possible complications from this?
An atherosclerotic aneurysm
• Pulsatile abdominal mass
• Ruptures into the retro-peritoneum and peritoneal cavity
Complications:
• Atheroembolism from associated atheroma
• Erosion of the adjacent vertebra
• Compression of the ureter
Describe a dissecting aneurysm
- Intimal tear develops, allowing blood to track to the media
- Blood proceeds along the media forming a dissection and degenerating the tunica media
- As it proceeds, branchesof the aorta are blocked, causing acute ischaemic damage
IMG 161
How does a patient with a dissecting aneurysm often present?
- Severe pain (usually back pain)
* Shock
What type of aneurysm is a thoracic aortic aneurysm an example of?
A dissecting aneurysm
IMG 162
Describe the heritability of dissecting aneurysms
Associated to a single DNA mutation (monogenic) which is autosomal dominant
Where do berry aneurysms often occur?
Circle of Willis or other brain regions
What are capillary microaneurysms also known as? How large are these?
Charcot Bouchard aneurysms
Smaller than 0.5mm
Describe the pathogenesis of syhilitic aneurysm
- Due to tertiary syphilis
- Tunica media undergoes ischaemic damage due to inflammation and narrowing of vasa vasorum
- This can cause aortic root dilatation and therefore aortic valve regurgitation
Describe the pathogenesis of a mycotic aneurysm
- A bacterial or fungal infection enters the vasa vasorum, most commonly cerebral arteries
- Usually secondary to bacterial endocarditis
Describe the pathogenesis of a cardiac aneurysm
What can this cause?
- Scarring following an MI leads to weakening of the left ventricular wall
- This wall dilates under the blood pressure inside the left ventricle
- An aneurysm forms which can be the cause of cardiac failure
IMG 164
What is heart failure?
Heart is unable to provide sufficient pumping action to maintain blood flow to meet the needs of the body
What are the primary cases of heart failure?
- Ischaemic heart disease
- Hypertension/Cor pulmonale
- Valvular heart disease
- Congenital heart disease
What tools are used to aid in a cardiac failure diagnosis?
Investigations: • Electrocardiography/Echocardiography • BNP: B type natriuretic peptide • Chest X-ray Clinical skills: • History • Cardiovascular examination
What is BNP: B type natriuretic peptide
Hormone released into plasma by stressed monocytes in cardiac failure
What are the effects of:
1) Left-sided heart failure
2) Right-sided heart failure
1) Acute: • Pulmonary oedema • Frothy, blood-stained sputum Chronic • Dyspnoea on exertion • Poor renal perfusion causing renin-angiotensin system activation
2)
• Peripheral oedema
• Raised JVP
• Hepatic congestion
What is congestive heart failure?
Concurrent left and right sided heart failure
Describe briefly the renin-aldosterone-angiotensin system
- Renin is an enzyme which converts angiotensinogen in the blood into angiotensin 1
- Angiotensin 1 is turned into angiotensin 2 by angiotensin converting enzyme (ACE)
