D: Vascular 3 Systemic Hypertension - Week 8 Flashcards
Define systemic hypertension. What is considered borderline? What is considered normotensive?
Hypertension: BP > 160/95
Borderline: BP = 140/90 - 160/95
Normotensive: BP <140/90
In general, what level of diastolic BP is considered too high and worthy of reducing?
Any diastolic BP > 100 mmHg
List 5 risk factors for hypertension
Obesity (bad cholesterol) Smoking Family history Older age Race: black
Define malignant hypertension
Diastolic BP > 120mmHg with associated exudative vasculopathy in retina and kidney
What percentage of hypertension are secondary? What 2 types of conditions can they be secondary to?
5% of cases. Renal conditions (e.g. nephritis, renal failure, tumour) Endocrine conditions (e.g. DM, hyperthyroid, cushing)
What is pre-eclampsia?
A pregnancy complication that generally occurs 20 weeks in where the mother experiences a sudden onset of high blood pressure
What can the height of blood pressure predict risk of? (5)
coronary artery occlusion stroke renal failure heart failure peripheral vascular disease
How can high blood pressure affect the brain? (2)
Damage to cerebral vessels can lead to:
TIA
Stroke
How can high blood pressure affect the kidneys? (2)
Endarteritic changes in renal bed
Ultimate renal failure from sclerosis
How can high blood pressure affect the heart? (2)
Left ventricular hypertrophy –> cardiac failure
BP damage to cardiac vessels –> myocardial infarction
What proportion of hypertension patients have a normal fundus?
1/3rd
What are the 2 main effects of hypertension on retinal vessels?
Constriction of arterioles
Arteriolar sclerosis
Why do arterioles constrict in response to hypertension?
to maintain homeostatic blood flow as perfusion pressure drops
A drop in perfusion pressure (as a result of systemic HT) means less blood flow. So the arterioles constrict, increasing TPR, and hence increasing blood flow back to normal values. this process is “autoregulation”
(remember. Occ. perfusion pressure = BP - IOP. Wait what? Shouldn’t it increase then? Come back to this)
How does arteriolar sclerosis affect the arterioles and how does this present on a fundus examination? (4)
Loss of wall transparency: copper wiring
Lumen narrowing: nicking
Deflection of veins at AV crossings: right angle X-ing
Vein lumen compression: banking
Retinopathy grading (Wong & Mitchell): - No retinopathy?
No detectable retinal signs with no systemic associations
Retinopathy grading (Wong & Mitchell): - Mild retinopathy? (description)
One or more of: Generalised arteriole narrowing Focal arteriole narrowing AV nicking Silver wiring
Retinopathy grading (Wong & Mitchell): - Moderate retinopathy? (description)
One or more of: Haem (blot, dot, flame) Microaneurysm CWP Hard exudates
Retinopathy grading (Wong & Mitchell): - Malignant retinopathy? (description)
Moderate retinopathy plus:
- optic disc oedema
Retinopathy grading (Wong & Mitchell):
- Systemic associations:
- mild retinopathy
- moderate
- malignant
Mild: Modest association with risk of stroke, coronary heart disease, mortality
Moderate: same but strong + cognitive decline risk
Malignant: strong assoc. with mortality
How is focal arteriolar constriction seen on fundus? Where?
Alternating zones of passive dilation and spasm
Most readily seen within 1-2DD of disc
How common is focal arteriolar constriction in established hypertension?
very common
What level of sensitivity does focal arteriolar constriction have for systemic hypertension?
Good sensitivity and specificity
What is venous banking and what causes it? What does this mean in relation to hypertension?
Refers to the increased dilation of the vein distal to the AV crossing (aka Bonet Sign) away from the disc. This occurs in response to restriction of venous return and is a reliable guide to the possibility of hypertension.
Define distal
away from the centre (in the case of distal dilation that means away from ONH)
What does venous banking indicate?
a significant interruption to vein blood flow
What does venous banking increase the risk of? How can this happen
thrombus formation and eventual venous occlusion
- this occlusion can occur because the veins endothelium can become sticky, leading to platelet adhesion to the walls
How can we bypass the AV crossing?
With shunt vessels
What causes flame haemorrhages?
leakage from superficial capillaries into the NFL
What are flame haemorrhages indicative of? (3)
Vascular occlusive disease
Diseases specifically affecting blood viscosity
Diseases affecting the integrity of the vessel wall
List 6 conditions that can present with flame haemorrhages
Glaucoma (esp LTG) Papillitis Papilloedema Following acute PVD Diabetic retinopathy Retinal Vein Occlusions
What are cotton wool patches?
occlusions of minor arterioles/capillaries serving the NFL leading to ischaemia with resultant cloudy swelling of axons (hence they look like cotton wool)
How long after vessel infarction does a CWP arise?
within 24 hours of infaraction
How long do CWPs persist?
about 6 weeks
As a result of how long they persist, do CWPs represent current or past vascular pathology?
Current/acute pathology
What is a common cause of CWPs?
moderately severe hypertension
What is papilloedema?
Non-inflammatory bilateral optic nerve head swelling as a result of blockage of axoplasmic transport
How does papilloedema present? (5)
Visible disc swelling + indistinct margins, and likely also:
- Venous engorgement, stasis + tortuosity
- Exudate
- Flame haemorrhages
- CWPs
List 4 differentials for papilloedema
CRVO
AION
Papillitis
Intracranial mass/pseudotumour
List 3 important individual signs of hypertension
Focal constriction of arterioles (incl. attenuation = straightening + thinning of arterioles)
Banking (bonet sign)
Flame haemorrhages
List 5 important signs in hypertension
- Cotton wool patches
- Papilloedema
- Vein occlusion
- Retinal arteriolar (macroaneurysm)
- Non-arteritic AION
What is Gunn’s sign?
Is where the blood column in the vein appears narrowed just upstream and downstream of the AV crossing (no banking occurring)
What is Sallus’ sign?
Is where there is a right angle formed at the AV crossing
Are gunn’s sign and sallus’ sign indicative of hypertensive retinopathy?
No! This isn’t hypertensive retinopathy
What 2 choroidal changes occur in hypertension?
Elschnig’s spots: (numerous small RPE detachments, little visual significance)
Siegrist’s streaks: (fine pigment lines folowing choroidal vessels which have sclerosed and occluded)
Rank from most important to least important the signs used in detecting early hypertension?
- Focal arteriolar constriction
- Vascular occlusions
- Banking particularly with shunt vesels
- Consider atherosclerosis in other signs
What are vascular occlusions evidence by in hypertension? (5)
Flame haemorrhages Lipid exudates Vein sheathing Banking CWPs
How can we manage patients with suspicion of hypertension?
- Refer to GP when signs of recent origin are seen (i.e. haem, CWP, papilloedema, RVO/BRVO, also ophthalm)
- may indicate need for BP tx or modification - Refer to ophthalm for: (recent vascular occlusion - CVO/BVO, AION, Macroaneurysm)
