Heart Failure, Treatment

Goals of Treatment

• Cure
• Slow/Prevent Disease Progression
• Symptomatic Relief

Treatments vary from surgical correction of underlying conditions, such as correction of a PDA, to management changes and pharmacological treatments.

Management Changes

1. Avoid strenuous exercise
2. Reduced Salt Diets (Reduces Preload)
3. Potassium Supplements
4. Taurine Supplements (Cats with dilated cardiomyopathy)
5. L-carnitine Supplements (Dogs with dilated cardiomyopathy)
6. Nutraceuticals (e.g. Omega-3 fatty acids, Anti-oxidants, Co-enzyme Q10)

Heart failure patients can suffer from cardiac cachexia due to the high metabolic demands of this condition. Make sure the patient is eating enough calories per day to maintain their body weight.

Pharmacological Intervention

The following terms are usfule when desribing the effects of various pharmacological agents:

• Preload=amount of maximal myocardial stretch (During Diastole)
• Afterload=amount of maximal myocardial tension (During Systole)

Drug treatments can be used to:

• Decrease Afterload (Increases flow by decreasing arterial tone)
• Increase Myocardial Systolic Function
• Increase Myocardial Diastolic Function

Decrease Preload

This decreases venous tone & fluid volume which can help to relieve congestion & edema Drugs in this class include:

1. Diuretics: These decrease blood volume by increasing sodium loss from the kidneys. They include loop diuretics, that act on the renal Loop of Henle such as Frusemide, and thiazide diuretics that act on the renal Distal Convoluted Tubule, such as Chlorothiazide or Hydrochlorothiazide. Potassium sparing diuretics act on the renal Collecting Duct and include Spironolactone and Amiloride.

2. Venodilation: Dilation of veins causes decreased venous pressures, blood redistribution, increased capacitance

-Venodilators

• Glyceryl trinitrate

-Balanced Vasodilators

• ACE inhibitors

• Alpha-antagonists

• Nitroprusside

Side Effects of Preload Reduction: hypovolemia, dehydration, hypokalemia, hyponatremia

Decrease Afterload

• Benefit: Reduce resistance to outflow, reduce cardiac work by decreasing systolic myocardial tension, increase blood flow

• Techniques

1. Arterial Vasodilators

• Hydralazine

2. Balanced Vasodilators

• ACE Inhibitors

enalapril (dogs & cats)

benazepril (cats)

Side Effects of ACE Inhibitors: vomiting, anorexia, diarrhea, hypotension, azotemia

Increase Myocardial Systolic Function

• Benefit: Helps with dilated cardiomyopathy & mitral valve disease (Dog & Cat)

• Contraindicated: Animals with hypertrophic cardiomyopathy (Dog & Cat)

• Techniques

1. Positive Inotropes

• Digitalis Compounds (e.g. digoxin, digitoxin)

• Calcium Sensitiser/Phosphodiesterase III. Inhibitor (e.g. pimobendan)

• Pure Phosphodiesterase Inhibitors (e.g. milrinone, amrinone)

• Catecholamines (e.g. dobutamine, dopamine)

Advantages:

-Stimulates myocardial contractility to improve cardiac output regardless of preload

Disadvantages:

-Increased myocardial work causes increased myocardial oxygen demand

Increase Myocardial Diastolic Function

• Benefit: Helps with hypertrophic cardiomyopathy and myocardial fibrosis where ventricular filling is compromised

• Techniques

1. Beta Blockers (e.g. atenolol, propranolol)

2. Calcium Channel Blockers (e.g. diltiazem)