Lecture 14: Hypertension Flashcards
What is blood pressure?
What is the formula?
-Pressure exerted by circulating blood upon the walls of blood vessels.
-Blood pressure decreases with increasing distance from the heart.
Usually refers to systemic arterial pressure measured at a person’s upper arm
systolic pressure divided by diastolic pressure
systolic pressure: peak pressure due to ventricular contraction
diastolic pressure: pressure during ventricular relaxation
What is normal blood pressure?
What is hypertension?
What is malignant hypertension?
normal range is 90/60mmHg to 140/90mmHg
systolic blood pressure is >140mmHg or the diastolic blood pressure is >90mmHg on two successive occasions.
systolic blood pressure is >200mmHg or the diastolic blood pressure is >140mmHg.
Systolic pressure more commonly elevated in older Px, and diastolic in younger(<50yrs) Px.
What is hypertension a risk factor for?
Stroke (ischaemic and haemorrhagic),
Myocardial infarction,
Heart failure,
Chronic kidney disease,
Peripheral vascular disease (e.g retinopathy),
Cognitive decline,
Premature death.
What are non modifiable risk factors for primary hypertension?
Increasing age
Race (higher risk in afro-caribbean people – occurs at a younger age)
Family history
Pregnancy
What are the modifiable risk factors for primary hypertension?
smoking
Too much salt (sodium) : causes your body to retain fluid, which increases blood pressure.
Too little potassium in your diet. . If you don’t get enough potassium in your diet or retain enough potassium, you may accumulate too much sodium in your blood.
Too little vitamin D in your diet. Vitamin D may affect an enzyme produced by your kidneys that affects your blood pressure.
Drinking too much alcohol. Over time, heavy drinking can damage your heart. Having more than two drinks a day can raise your blood pressure.
Stress.
How can hypertension effect inner retinal vasculature?
How can hypertension affect choroidal vasculature?
Autoregulation of arteriole diameter to moderate blood flow (vasoconstriction caused by raised BP)
Tight junctions in walls form blood-retinal barrier.
Choroidal arterioles and capillaries have fenestrations (ie, no blood-ocular barrier) and do not exhibit autoregulation.
What is hypertensive retinopathy?
What can long term hypertension cause?
I-ncreased blood pressure causes constriction of retinal arterioles (autoregulatory mechanism).
-Chronic vasospasm leads to diffuse and focal arteriolar narrowing and increased vascular tortuosity.
arteriolosclerosis (thickening of arteriolar wall due to progressive hyalinisation and increase of elastic and muscular components).
What is the classification for hypertensive retinopathy?
1 (chronic):
-Mild to moderate narrowing or sclerosis of the arterioles
2 (chronic):
-Moderate to marked narrowing of the arterioles
-Local and/or generalised narrowing of the arterioles
-Exaggeration of the light reflex
-Arteriovenous crossing changes
3(Acute; symptomatic):
-Retinal arteriolar narrowing and focal constriction
-Retinal oedema
-Cotton wool spots
-Retinal haemorrhages
-Hard exudates
4 (Acute; Malignant; Symptomatic)
As for Stage 3 plus optic disc swelling
What are the signs of hypertensive retinopathy stage 2?
straightening and narrowing of arterioles
tortuosity
changes in light reflex:
-copper wire appearance
-silver wire appearance as sclerosis advances
-nipping
-deflection of the venule, righting angling, or bridging
-segment of vein after crossing may be larger, darker and tutrous
-BRVO
What causes stage 3 and 4 hypertensive retinopathy?
What are the signs?
-Disruption of blood retinal barrier
- increased vascular permeability.
-With severe hypertension, arteries lose ability to autoregulate
-damages capillary and arteriole vessel walls as unregulated pressure reaches small vessels.
microaneurysms, obstruction of arterioles, and formation of cotton wool spots (sign of retinal ischaemia).
What can increased vessel permeability in stage 3 HR cause?
Haemorrhages (often flame shaped)
Retinal oedema
Hard exudates
Deposition of hard exudates around fovea in Henles layer : Macular star
What are the signs of stage 4 HR?
swelling of optic disc
features from stage 3
indicates malignant hypertension
What are the symptoms of malignant hypertension?
What causes it?
headaches, diplopia, scotomata, dimness in vision, photopsia, chest pain, nausea/vomiting, shortness of breath, weakness.
very high blood pressure. Fibrinoid necrosis of end arterioles due to unregulated pressure results in organ damage.
What stage of HR is hypertensive choroidopathy seen?
What are the signs?
stage 3-4
choroidal ischaemia
Yellow spots in RPE which leak on fluorescein angiography seen overlying non-perfused vessels i.e. ischaemic infarcts of RPE
Chronic: Yellow spots replaced by regions of RPE clumping surrounded by atrophic areas (Elschnig spots).
Hyperpigmented flecks arranged in a linear fashion (Siegrist streaks) develop overlying sclerosed choroidal vessels.
Focal RPE detachments, serous retinal detachments, and cystoid macular oedema can also occur.
What is the link between DM and HTN?
What is the difference between HR and DR?
Prevalence of diabetes is high in px with hypertension (especially with Stage 3-4 hypertensive retinopathy).
Hypertensive retinopathy (stage 3) tends to show a ‘drier’ retina
DR (R3): lots of cotton wool spots, but sparse haemorrhage, oedema, exudates. DR is often ‘wetter’.
