Cardiology: Vascular Diseases Flashcards
How can blood pressure be directly and accurately assesed?
Arterial needle stick, catheter placement with pressure transducer
When is blood pressure recording indicated?
- Assessing severity of heart disease- hypotension
- Identification of systemic hypertension- renal disease, hyperadrenocortiscm, diabetes
- Assessing response to drugs
What are the two indirect methods of recording blood pressure?
- Doppler technique- cuff on forelimb
- Oscillometric technique- cuff also
How does the doppler technique of recording work?
- A cuff is positioned on forelimb
- Blood flow in the artery distal to cuff is recorded by doppler probe
- Cuff is inflated until flow is occluded then gradually deflated
- As soon as flow is detected again the corresponding pressure is recorded
- Not acurate for diastolic pressure or mean
- Hypotension >175, >150 abnormal
How is blood pressure measured with an oscillometric technique?
- Cuff with a semi-automated machine
- Inflated above systollic pressure
- Gradually decreased until oscillations in pressure within cuff detected as flow returns
- Corresponds with systolic pressure
- As cuff further deflates maximal oscillations are recorded at mean arterial
- No oscillations at a point below diastollic pressure
What are consequences of hypertension?
- Ocular- can cause irreversible blindness
- CNS- complications include cerebrovascular accidents
- Cardiac complications- concentric LV hypertrophy, new heart murmurs, progression of degenerative valvular disease can be accelerated
- Renal- proteinuria renal dysfunction also causes hypertension
How should systemic hypertension be treated?
- Treat underlying cause
- Amlodipine- drug of choice
- If significant proteinuria- ACE inhibitors or Angiotensin II receptor blockers (will reduce BP)
- If cause known more specfic anti-hypertensice meds can be used
What are the three changes that can cause a blood clot?
(Virchow’s triad)
- Stasis of blood flow
- Hyper-coagulable state
- Damaged endothelium
What are the usual reasons for arterial thrombosis in cats?
- Normally forms in LA
- Due to myocardial disease associated with LA dilation
- Reflects stasis of blood flow and possibly damaged endocardium
- Cats platelets are highly reactive
- Embolization results in further activation
Where does embolisation usually occur in cats?
How do they present?
Feline Arterial Thromboembolism (FATE)- saddle thrombus
* Severe, acute pain, loss of function of back legs, cold limbs, cyanotic nail beds
* Muscles painful and in spasm (ishaemic neuropathy)
What is the treatment for thromboembolism in cats?
Prognosis is grave
* Depends on adequate pain control- opiates
* ACP- anxiolytic and vasodepressor of collateral vessels
* Clopidogrel- antiplatelet drug, inhibiting binding of ADP
* Aspirin
* New anti-factor Xa drugs- Apixaban, Rivaroxaban
* Heparin- reduced activation of coagulation cascade
* Clost busting drugs- tissue plasminogen activator may be effective within 6 hours
Risk of bleeding and reperfusion complications
What usually casues thromboembolism in dogs?
Endocrinopathies
Hypothyroidism
Hyperadrenocorticism
How do dogs present with distal aortic thromboembolism?
- More chronic
- Hindlimb weakness- excercise
- More likely to present for neurological or orthopaedic investigation
- Check femoral pulse, color of nail beds (non-pigmented), temp of hindlimbs
Treatment for underlying condition, against thromboembolism similar to cats
How can thromboembolism be prevented?
In at risk patients
* Clopidogrel
* Low dose aspirin
* Apixaban or Rivaroxban
* Low molecular weight heparin (dalteparin)
What can cause thromboembolism in the dogs?
- Most commonly- endocrinopathies
- Protein losing nepropathy/enteropathy
- Pro-inflammatory conditions
