Heart Disease/Failure, Congenital Dz Flashcards
Four components that make up stroke volume (SV)
1) Systolic function = contractility
2) Diastolic function = how well and how fully the heart relaxes
3) Preload = how much blood is in the heart before it contracts (atrial P, end of diastole)
4) Afterload = resistance to blood leaving the heart (systemic vascular R)
Difference between heart disease and failure
> Failure = physical/functional cardiac abnormality
Disease = physical state where CO is inadequate to meet the needs of the organ system metabolism, despite adequate preload (not due to dehydration or hypovolemia)
*Disease = showing clinical signs
True or false - atrial pressure rises with inadequate systolic and diastolic funciton
TRUE
What does the S1 heart sound indicate?
Blood suddenly stopping at closed AV valves - SYSTOLE
What does the S2 heart sound indicate?
Blood suddenly stopping at closed aortic and pulmonic valves - DIASTOLE
What does the S3 heart sound indicate?
Sudden end of rapid ventricular filling - DIASTOLE
What does the S4 heart sound indicate?
Blood suddenly stopping as the atria contract, forcing blood into the ventricles - DIASTOLE
What does pulse deficits indicate?
> Auscultating a heart beat without palpating a peripheral pulse
- Inadequate filling time = didn’t have enough force to create a pulse
- Arrhythmia (irregular rhythm) + pulse deficits = most likely pathologic
What does a gallop rhythm indicate?
> Summated sound of S3 and S4
*Indicates STIFF VENTRICLES
What three things must you determine with heart murmurs?
1) Location
2) Timing - systole, diastole, continuous, sys-diastole
3) Grade (loudness)
What are two main categories of clinical signs that accompany heart disease?
1) Low cardiac output signs = decreased forward flow
2) Congestive signs = increased backward pressure
Clinical signs of low cardiac output
> Decreased forward flow
*Same signs, no matter which ventricle is at fault
+ Prolonged CRT
+ Weak femoral pulses, distal pulses may not be palpable
+ Cool peripheral limbs, decreased core temp
+ Cyanosis = low CO or R-to-L shunt
What does congestive signs indicate?
> > Atrial pressures are elevated due to poor ventricular function
- Increased pulmonary vasculature pressure due to back up in L. atrium
- Fluid leaks into lung tissue = pulmonary edema
- Fluid leaks into body cavities (R. atrium)
Clinical signs of congestive right sided failure
> Increased backward pressure \+ Jugular distension \+ Hepatomegaly \+ Ascites \+/- Peripheral edema \+/- Arrhythmias
What does jugular distension indicate?
Right sided heart failure - increased right atrial pressures
Clinical signs of congestive left sided failure
> Increased backward pressure \+ Pulmonary venous congestion (radiographic dx) \+ Pulmonary edema \+ Signs of decreased output \+/- Arrhythmias
Definition and criteria for innocent puppy cardiac murmurs
- Soft = no louder than grade III
- Systolic murmurs
- Uncertain etiology
- Puppies that are 12-16 weeks
- PMI = left base
- *NOT associated with clinical signs
Differential diagnoses for left basilar systolic murmurs (5)
- Aortic or subaortic stenosis
- Pulmonic stenosis
- VSD - relative
- Atrial SD - relative
- Physiologic = anemia, pyrexia
Big three diagnostic tests in cardiology
(PE and history) 1) ECG - electrical info 2) Radiographs = external cardiac abnormalities, vasculature, lungs 3) Echo - internal cardiac abnormalities \+/- Angiography
Differential diagnoses for right MEA shift
1) Right ventricular enlargement/hypertrophy
2) Conduction disease = right bundle branch block (normal P wave)
Differential diagnoses for left MEA shift
1) Left ventricular hypertrophy/enlargement
2) Conduction disease = left bundle branch block (normal P wave)
How do you differentiate between bundle branch blocks and hypertrophy patterns on ECG?
- Enlargement = narrow and upright QRS, normal
- Conduction disease = wide QRS = takes longer to conduct
ECG findings with pulmonic stenosis
Right MEA shift = due to right ventricular hypertrophy
Radiographic findings with pulmonic stenosis (2)
1a) Right ventricular enlargement (VD)
1b) Wide heart with apical elevation (lateral)
2) Main pulmonary artery bulge (1 o’clock)
Echo findings with pulmonic stenosis (5)
- Right ventricular hypertrophy
- Right atrial enlargement
- Thick leaflets and incomplete opening of pulmonic valve
- Distal (to the stenosis) dilation of the pulmonary artery
- Small left heart
- Fractional shortening = 29% = measure of contractility
Breed/sized dogs at risk for pulmonic stenosis
- Small breed dogs = maltese, beagle, boxer, chihuahua, etc.
- Larger brachycephalic breeds = english bulldog, etc.
Reason for right ventricularhypertrophy and atrial dilation with pulmonic stenosis
> Hypertrophy = need to overcome the pressure of the stenotic pulmonary valve
Dilation = increased volume of blood from fluid back-up, ventricle doesn’t empty completely
Source of the right basilar murmur with pulmonic stenosis
Stretching of the tricuspid valve due to increased pressure of the right ventricle - hearing the regurgitation
Possible complications of right ventricular hypertrophy (2)
- Ischemia from coronary artery trying to perfuse the thick and stiff ventricular wall
- Fibrotic endocardium can lead to decreased elasticity and hypoxia can cause arrhythmias
Clinical signs of pulmonic stenosis heart failure
+ Ascites
+ Jugular distension
+ Pleural effusions
+ Hepatomegaly
Heart murmur heard with aortic stenosis
Left basilar systolic murmur
Breeds/sized dogs associated with aortic stenosis
Large breed dogs, Ex: boxer, bull terrier, german shepherd, golden retrievers, etc.
Which chamber(s) would be thickened with aortic stenosis?
Left ventricle
Which chamber(s) would be dilated with aortic stenosis?
- Left atria
- Post stenotic dilation after the aortic valve
What secondary problems do you see with aortic stenosis? (2)
- Fibrosis of the left ventricle = decreased elasticity, hypoxia and risk of arrhythmias
- Severe stenosis can lead to sudden death
Which clinical signs of heart failure do you expect to see with aortic stenosis?
+ Pulmonary edema = crackles
+ Coughing
+ Dyspnea
+ Shortness of breath or exercise intolerance
Therapy and treatment for pulmonic stenosis (3)
- Nothing with mild to moderate lesions
- Medical therapy
- Balloon valvuloplasty
- Surgical palliation = stretch valve or pericardial patch graft
Medical therapy used to treat pulmonic and aortic stenosis
- CHF meds = furosemide, pimobendan, ACE inhibitor
- Anti-arrhythmics
- Beta blockers
Therapy and treatment for aortic stenosis
- No therapy with mild to moderate cases
- Medical therapy
- Balloon valvuloplasty - more difficult to stretch than pulmonic, chance of recurrence
- Surgical removal of obstruction
How do beta blockers help treat pulmonic and aortic stenosis?
> Slow the HR enough to allow for the ventricles to fill between heart beats
Increase coronary perfusion during diastole
Do we commonly use vasodilators for treatment of pulmonic and aortic stenosis?
NO - animal has no way of compensating the drop in BP with vasodilation, with an increase in CO or HR (with a outflow obstruction)
Which condition are arrhythmias more common in - pulmonic or aortic stenosis?
Aortic stenosis - reason is unknown
Which condition do we more commonly see endocarditis with - pulmonic or aortic stenosis?
Aortic stenosis
PE findings consistent with a PDA
- Continuous murmur at the left heart base
- Systolic murmur
- Bounding pulses = feel stronger than normal
- Exercise intolerance
+/- Left apical murmur
What does bounding pulses indicate? Esp with PDA’s
Wide pulse pressure = large difference between systolic (higher than normal in descending) and diastolic (less than normal in the main pulmonary artery) pressures
Pathology and blood flow abnormalities of PDA’s
> Blood is diverted from the main pulmonary artery to the descending aorta
- Continuous murmur = due to blood flowing during systole and diastole
- Left sided overload = blood coming from the left atrium is from the lungs AND the pulmonary artery
- High aortic pressure compared to the pulmonary artery, in systole and diastole
ECG abnormalities with PDA’s (4)
> Premature (ectoptic) beats = tall and narrow = supraventricular, due to atrial stretching
- Normal sinus rhythm + tachycardia
- Wide P waves = atrial enlargement
- Tall R waves = LV enlargement pattern
Radiographic findings with PDA’s (4)
- Left ventricular enlargement
- Left atrial dilation
- Pulmonary overcirculation = pulmonary vein and artery enlargement
- “Ductus” bump = bulge in descending aorta
Three main disorders that lead to volume overload
1) Shunts = PDA, VSD, ASD
2) AV valve dysplasia (mitral or stenosis)
3) Semilunar valve malformations = aortic or pulmonic insufficiency (rare)
Which side of the heart fails with PDA’s?
Left side = has to deal with the extra volume from the lungs and the pulmonary artery
PE findings with VSD’s
- Right SYSTOLIC murmur at the sternum
- RELATIVE left basilar systolic murmur (suspect pulmonic valve)
+ Signs of left sided CHF
Which side fails, normally, with VSD’s?
- Left side needs to pump to the aorta + right side (lower pressure)
- Both sides squeeze at the same time = blood goes out the pulmonary artery (right side doesn’t enlarge)
**Pulmonary artery sees the blood from the right side AND some from the left side, dumps it on the left side
» LEFT SIDE FAILS
Radiographic findings of VSD
- Left ventricular enlargement and left atrial dilation
- Variable right sided enlargement
+ Pulmonary edema, consistent with L. CHF - Pulmonary overcirculation
ECG abnormalities with VSD’s
*Often normal
+/- Left sided heart enlargements = left MEA shift, tall R waves
Why do we hear both a systolic R sternal murmur and a left basilar systolic murmur with VSD’s?
- Systolic sternal right sided = VSD mumur
- RELATIVE left basilar murmur, suspect the pulmonic valve because more blood is going through the valve (valve is normal)
Which side fails with ASD’s?
> RIGHT SIDE
- Blood from the left side is shunted to the right side = volume overload
What heart murmurs do we hear with atrial septal defects?
*DON’T hear basilar murmur because the pressure differences between the atria is minimal
- Left systolic basilar murmur = relative pulmonic murmur due to volume overload
+/- Tricuspid valve regurg murmur
Radiographic signs of ASD’s
- Right sided enlargement
- Right CHF = hepatomegaly, pleural effusion
- Pulmonary overcirculation
ECG abnormalities of ASD’s
+/- Right axis shift due to enlargement
- Tall P waves = atrial dilation
- Sinus tachycardia
+/- Other arrhythmias
Treatment for PDA’s
- Surgical ligation from the outside (open chest)
- Intravascular coil or Amplatz occluder from the inside (via the femoral a.)
- Medical therapy (like in humans) doesn’t work = lining of the ductus isn’t normal that PGF’s will work to close it
Cause of reversed PDA
> Right to left shunting
- Intima thickening and medial hypertrophy in pulmonary artery due to excessive flow = increased vascular resistance
- Pulmonary artery P exceeds aortic P = shunt occurs
Clinical signs of reversed PDA
- Front end (mucous membrane) = pink
- Hind end = blue MM
- Right ventricular hypertrophy
- Rear limb weakness with exercise
- Long standing cases have cyanosis
- Clin path = polycythemia due to chronic hypoxia
> > Due to oxygenated blood goes to the brain, unoxygenated blood goes to the limbs
Most common congenital disease in cats (2)
1) Mitral valve dysplasia
2) VSD’s
* Stenoses are not common
Four components of tetralogy of Fallot
1) Pulmonic stenosis
2) Right ventricular hypertrophy
3) Overriding aorta
4) VSD
What decides which direction the blood flows through a VSD with tetralogy of Fallot? Presence of cyanosis?
> > Degree of pulmonic stenosis
- Severe pulmonary stenosis = R-to-L shunting = CYANOSIS
- Mild stenosis = L-to-R shunting = behaves like a VSD (no stenosis)
