Cardiovascular Flashcards
(70 cards)
List the 6 classifications of pulmonary hypertension:
- Primary pulmonary arterial hypertension
- Left-sided heart disease
- Respiratory disease/hypoxia
- Pulmonary emboli/pulmonary thromboembolism
- Parasitic disease
- Multifactorial or unclear mechanisms
List 3 etiologies of pulmonary hypertension and an example for each
- Increased pulmonary blood flow
- Congenital left-to-right shunt due to intra or extra cardiac defects - Increased pulmonary vascular resistance
- Pulmonary endothelial dysfunction
- Pulmonary vascular remodeling
- Perivascular inflammation
- Vascular luminal obstruction
- Increased blood viscosity
- Arterial wall stiffness
- Lung parenchymal destruction - Increased pulmonary venous pressure
- Left heart disease
* LV systolic dysfunction
* LV diastolic dysfunction
* Inflow obstruction
* Valvular disease (acquired or congenital)
- Compression of a large pulmonary vein
What is a normal fractional shortening in dogs?
Between 25% and 45% in most dogs.
Formula for fractional shortening
FS = ([LVEDD - LVESD]/LVEDD) x 100
Generally, dogs with L-CHF have severe LA dilation visible on right parasternal short-axis heart base views (with LA:Ao ratio usually >2:1). What is an exception to this rule?
Peracute chordae tendineae rupture - the sudden massive worsening of mitral regurgitation causes LA pressures to quickly rise and cause pulmonary edema BEFORE the LA has time to dilate and remodel.
What are some echocardiographic features of advanced MMVD?
- Thickened mitral valve
- Severe mitral regurgitation
- Severe LA enlargement
- LV volume overload (eccentric hypertrophy) with normal to hyperdynamic LV systolic function.
What are some echocardiographic features in dogs with L-CHF secondary to MMVD in the right parasternal long-axis 4-chamber view?
- Thickened mitral valve
- Possible prolapse of a leaflet into the LA
What are some echocardiographic features in dogs with L-CHF secondary to DCM?
- LV is severely dilated and spherical
- LV systolic function is markedly hypodynamic (FS < 20%)
- Normalized LV end-diastolic diameters of >1.9.
- Normalized LVEDD is LVEDD/body weight or BSA
In a dog with L-CHF and cardiogenic shock, what would pericardial effusion on echocardiogram/POCUS suggest?
- LA rupture secondary to severe MMVD
- A crescent-shaped thrombus may be visible within the pericardial space
What are the most important echocardiographic and clinical features of DCM?
Echocardiogram:
1. Severe LV dilation
2. Severely decreased LV systolic function
Clinical Features:
1. Tachyarrhythmias
2. Soft or absent murmurs
What are the focused ultrasound criteria for cardiac tamponade?
- Diastolic collapse of the RA (and possible RV)
- Distended CVC with decreased collapsibility
What are two conduction abnormalities not associated with bradycardia and clinical signs?
- Bundle branch block
- First-degree AV block
Third-degree AV block in cats is often associated with…?
Structural heart disease
What a the most common indications for temporary pacing?
- Acute onset of AV block causing frequent syncope
- Severe bradyarrhythmia associated with hemodynamic instability during anesthesia
Echocardiogram findings that support a clinical diagnosis of R-CHF include?
- RA dilation
- RV dilation or hypertrophy
- Large indistensible CVC
(reflective of underlying severe structural right heart disease and/or elevated systemic venous pressures)
What does a vasovagal event look like on EKG?
A brief period of sinus tachycardia before a sudden drop in heart rate, and a long period with no or few beats. Then a progressive return to a normal heart rate.
How does severe left heart disease lead to pulmonary arterial hypertension?
Also called postcapillary PAH - severe left heart diseases causes a passive backup of elevated pulmonary venous pressure across the capillary bed, and consequently elevated pulmonary arterial pressures.
Define sick sinus syndrome
A disease of the conduction system characterized by periods of normal sinus rhythm or sinus bradycardia, interspersed with long sinus arrest/block that can last up to 10 or 12 seconds because junctional and ventricular pacemakers fail to initiate escape beats.
What makes SVT pathologic?
Pathologic SV tachyarrhythmias are primarily related to diminished ventricular filling and subsequent low cardiac output associated with the rapid heart rates and myocardial dysfunction that can eventually lead to tachycardia induced cardiomyopathy if SVT is frequent and sustained.
Describe cardiac tamponade
Develops when the pressure in the pericardial sac exceeds that of the RV end-diastolic pressure, resulting in diminished RV diastolic
filling and low cardiac output.
How do you diagnose post capillary PAH on echo?
- Look for evidence of severe left heart disease
- Measure systolic pulmonary artery pressures with tricuspid regurgitation velocity
True or False: Sinus bradycardia is rarely a primary
disorder or a cause of clinical signs.
True; much more likely secondary to systemic disease causing increased vagal tone (ie., gastrointestinal, respiratory, neurologic, and ocular diseases). In these cases, resolution of the primary disease results in an increased heart rate with no need for medical or pacemaker therapy.
What are some causes of AV block?
What is the most common cause of AV block in dogs?
- Myocardial fibrosis, inflammation or
infiltration - Potentially drug toxicity (calcium channel blockers, beta blockers, digoxin).
Age related fibrosis is the most common cause of AV block in dogs.
Mild elevation of plasma cardiac troponin I level is common in dogs.
Describe the vagal maneuver and how it works?
Common vagal maneuvers include:
1. Applying pressure to the carotid
sinuses
2. Applying pressure to the ocular and periorbital regions, and
3. Applying pressure to the nasal planum in the cat
The increase in pressure in these regions triggers an increase in parasympathetic output to the heart via the vagus nerve resulting in slowing of AV nodal conduction. Slowing AV nodal conduction can either terminate the SVT or slow the ventricular response rate, which can be both diagnostic and therapeutic.
