Cardiac_Disease-1.ppt in canine & feline

good idea with sufficient knowledge

1. Heart Failure
Department of Veterinary Medicine
Bihar Veterinary College, Patna
(Bihar Animal Sciences University, Patna)
By
Dr. Pallav Shekhar
Asstt. Professor

2. Heart Failure
Heart failure is not a specific disease.
It is a syndrome in which severe dysfunction results in failure of the
cardiovascular system to maintain adequate blood circulation.

3. Heart failure, the blood flow is insufficient to supply organs with enough
oxygenated blood for proper function.
Depending on the degree of severity, signs of heart failure may appear
while the dog is at rest.
During mild exertion,
Or
during moderate or extreme exercise.

4. Heart Failure
Chronic Heart Failure
Acute Heart Failure

5. Chronic Heart Failure
Heart failure is the most common clinical presentation of dogs and cats
with heart disease.
Congestive heart failure (CHF) implies that there is a damming back of
blood behind the failing heart, into the pulmonary or systemic
circulations.
Congestive heart failure is a sequel to many of the various causes of heart
failure

6. Etiology
Valvulardisease
Endocarditisresulting in either valvularstenosisor valvular
insufficiency
Congenital valvular defects –most commonly valvularstenosis,
Rupture of valve or valve chordae.

7. Myocardial disease
Myocarditis -bacterial, viral, parasitic ortoxic
Myocardial degeneration -nutritional
toxic
TRP
Congenital or hereditary

8. Types of CHF
CHF
RCHF LCHF

9. LEFT CONGESTIVE HEART FAILURE
Left backward failure will result in increased pulmonary venous pressures
and ultimately pulmonary oedema.
Breathlessness is therefore a very sensitive index of left backward failure.
RIGHT CONGESTIVE HEART FAILURE
Right backward failure will result in increased pressure in the vena cava,
jugular distension, liver congestion, ascites and pleural effusion.

10. Right Congestive Heart Failure
Therightatriumreceivessystemicandcardiac
venousandlymphaticdrainageviathecranialand
caudalvenacavaeandthecoronarysinus.
Rightatrialpressureincreasesasrightheart
diseaseworsensduetodiseasessuchastricuspid
valveinsufficiencyandpulmonaryhypertension

11. Backward Failure
Backward (congestive) failure refers to the damming back of
blood behind the failing heart.

12. Backward Failure

13. Clinical Signs
Distended Jugular Vein
Pleural effusion
Hepatomegaly
Ascites

14. Forward Failure
Forward failure refers to the inability of the heart to pump
blood in a forward direction, i.e. out through the aorta. This
results in a reduction in systemic blood pressure, which acts
as the primary stimulus to inciting the reflex compensatory
mechanisms

15. Clinical finding Pathophysiological
mechanism
Exercise intolerance Poor muscle perfusion
Pale mucous membranes and cold extremities
Peripheral
vasoconstriction
(sympathetic and
angiotensin activation)
Tachycardia Sympathetic activation
Weak femoral pulses (most marked with the systolic failure seen in
dilated cardiomyopathy)
Poor left ventricular
contractility
and reduced stroke
volume
Elevated blood urea and creatinine, and oliguria Poor renal perfusion
Increased thirst Angiotensin II stimulation

16. Left backward failure will result in increased pulmonary venous pressures
and ultimately pulmonary oedema.
Breathlessness is therefore a very sensitive index of left backward failure.
LEFT HEART FAILURE

17. ForewardFailure

18. Clinical Signs
Mainly pulmonary components, which on exertion causes
Cough
Paroxysmal dyspnea or cardiac asthma
Cyanosis
Hemoptysis
Varying degrees of pulmonary edema

19. Diagnosis
History
Clinical Signs
Physical Examination SRR
ECG
X ray
Echocardiography

20. Treatment
(1)Reduce cardiac work
(2)Reduce excessive volume overload (preload) and cardiac
dilation
(3) Improve cardiac efficiency

21. Reduce cardiac Work
Rest
Cardiac work can be reduced by rest, reducing arterial pressure (afterload)
by counteracting the excessive vasoconstriction and reducing the filling
pressure (preload).
Arterial and venous pressures can be reduced by the use of vasodilator
drugs, e.g. hydralazine, nitroglycerine (glyceryl trinitrate), enalapril or
benazepril.
Preload is also reduced by reducing the volume overload, e.g. by diuresis.

22. Vasodilators
Vasodilators exert a positive effect in CHF through dilating systemic
arterioles and Veins
Nitrates( Nitroglycerin, Sodium nitroprusside):
Dramatically reduce Preload and after load
Sodium nitroprusside is used as 5mcg/kg/hr
Amlodipine(Calcium Channel Blockers)
Eg; Atenolol: 6.25-12.5mg/kg/day

23. Reducing Volume Overload
These can be reduced by cutting sodium intake, e.g. low salt diets,
diuresis and inhibition of angiotensin converting enzyme (thus
production of angiotensin II and aldosterone)
ACE inhibitor
Enalapril 0.5mg/kg orally twice
Benazepril 0.25mg-0.5mg/kg/day

24. Diuretics
Useful in Oedema and Effusion in HF.
Loop Diuretics
Furosemide
IV onset of action is 5 min, oral 60 min
Emergency treatment of Pulmonary edemarequire high doses IV or IM 4-
8mg/kg for dogs and 2-4mg/kg for cats.
Spironolactone: 1-3 mg/kg body Wt. one or twice

25. Improving myocardial efficiency
Improving myocardial efficiency may be attempted with
Positive inotropic drugs.
Positive lusitropes
Antiarrhthymics

26. Positive inotropes
Pimobendan: AV valve insufficiency and DCM
0.2-0.3mg/kg body wt bid
Digoxin: Weak positive inotropes
0.003-0.005mg/kg body weight