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
What can cause pulmonary hypertension?
- Pulmonary vascular changes- complex congenital heart diseases (Eisenmengers)
- Dirofilaria, Angiostrongylus
- Left sided CHF- high left atrial pressure
- Pulmonary thromboembolism
- Resp conditions- brachycephaclic obstruction
How is pulmonary hypertension diagnosed?
Clinical signs- loud heart sound (S2)- murmur or tricupsid regurgitation
Radiographs- right heart enlargment, pulmonary arterial dilation
Doppler echocardiography- tricupsid/pulmonary regurgitation
What is calculated on doppler echocardiography for diagnosis of PH?
- Tricupsid regurgitation velocity- RV to RA pressure gradient
(pulmonary arterial systolic pressure) <25mmHg normal - Pulmonic regurgitation velocity used to determine pressure gradient between pulmonary artery and RV in diastole <10mmHg normal
How is pulmonary circulation treated?
- Drugs used as vasodilators can have effect on pulmonary vasculature
- Pimobendan- phosphodiesterase V inhib, PDE III inhibition
- Sildenafil (viagra)
How can pulmonary thromboembolism be diagnosed?
What can be used for treatment?
Arterial blood gas analysis is identified by large Alveolar to arterial oxygen gradient
FDPs (fibrin degredation products) or D- dimers (more specific)
What is the intermediate host for dirofilaria immitis?
Where do L5 reside?
What is the PPP?
What does it cause?
How can large worm burdens be identified?
- Mosquito is intermediate
- L5 in pulmonary arteries- release microfilaria into blood
- Causes pulmonary hypertension
- Large worm burneds seen on echocardiography in RA and RV, antigen tests, blood microfilaria tests, Antibody tests
How is heart worm disease (dirofilaria immitis) treated?
- Mechanical removal of worms is indicated with heavy burdens
- Adulticide
- Microfilariacide- 3-4 weeks after adulticide- Ivermectin, milbemycin oxime
Prevention
* Ivermectin, milbemycin, moxidectin- monthly
- What it the intermediate host of angiostrongylus vasorum?
- Whats the PPP?
- What can it result in?
- What are the clinical signs?
- What is the treatment
- Mollusc
- PPP- 7-9 weeks
- Pulmonary hypertension
- Respiratory, coagulopathy, neurological (larval migration)
- Milbemycin oxime or moxidectein or fenbendazole
