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Congestive heart failure/cor pulmonale
Synonym(s): brisket disease
Introduction
- Congestive heart failure can be unilateral or bilateral, acute or chronic.
- The term 'Cor Pulmonale' relates to pulmonary cardiovascular disease and relates to right sided heart failure secondary to (usually chronic) pulmonary artery hypertension.
- Cause: underlying heart disease → either poor systolic function, poor diastolic function, volume overload, pressure overload, compliance failure or dysrhythmias → if severe enough → congestive heart failure syndrome (CHF).
- Signs: syndrome characterized by fluid retention. Left congestive heart failure leads to pulmonary edema, whereas right congestive heart failure leads to pleural effusion and occasionally ascites.
- Affected animal uses normal homeostatic mechanisms of cardiovascular system (activation of sympathetic nervous system and other neuroendocrine systems), to maintain blood pressure → detrimental in chronic cases → decreased cardiac function → progressive vicious cycle.
- Diagnosis: clinical signs, echocardiography.
- Treatment:
- Treatment involves specific measures to treat the underlying heart disease, control fluid retention, counter adverse neuroendocrine activation, correct dysrhythmias (if present) and improve systolic or diastolic function.
- Treatment is rarely economically viable in cattle, but may be attempted in very valuable animals.
- Drugs are not ususally licensed for use in cattle.
- Prognosis: Poor - only palliative treatment is available and normally not a viable option.
Cost considerations
- Depends on underlying heart disease and specific treatment required.
- Cost associated with mortality and culling losses.
Special risks
- Stress.
- Sedation and anesthesia likely to cause cardio-respiratory depression, although these would normally not be undertake in animals in heart failure.
Pathogenesis
Etiology
Causes of left-sided CHF
- Dilated cardiomyopathy - Bovine dilated Cardiomyopathy Cardiomyopathy.
- Patent ductus arteriosus Patent ductus arteriosus.
- Ventricular septal defect Ventricular septal defect.
- Neoplasia, eg Lymphoma of the myocardium
Causes of right-sided CHF
- Pericardial disease, e.g. secondary to traumatic reticulitis Traumatic reticulitis.
- Tricuspid valve disease, e.g. vegetative valvular endocarditis Endocarditis.
- Pulmonary hypertension.
- Brisket disease/ Bovine high altitude disease is seen worldwide and causes pulmonary arterial hypertension leading to right sided heart failure.
- Cor pulmonale arises as a result of increased pulmonary artery pressure due to changes in pulmonary vascular bed: vasoconstriction (e.g. Alveolar hypoxemia) or obstruction (e.g. embolus).
Pathophysiology
Categories of underlying heart disease
- Systolic failure, e.g. due to dilated cardiomyopathy.
- Diastolic failure, e.g. due to pericardial disease or hypertrophic cardiomyopathy
- Volume overload, e.g. due to mitral or tricuspid valve endocarditis, patent ductus arteriosus PDA, ventricular septal defect VSD.
- Pressure overload, e.g. due to severe systemic hypertension, (very rare in cattle pulmonary hypertension).
- Dysrhythmias: ventricular tachycardia, supraventricular tachycardia, atrial fibrillation, third degree atrioventricular block (rare). Dysrhythmias
Effects
- Decreased cardiac output → decreased blood pressure → activation of baroreceptors → reflex increased sympathetic activity/decreased vagal activity → increased heart rate, increased contractility and vasoconstriction → maintain blood pressure.
- Sympathetic activation and poor renal perfusion → activates renin-angiotensin-aldosterone system (RAAS) → further vasoconstriction, sodium and water retention → increased sympathetic outflow and release of vasopressin (antidiuretic hormone) → further vasoconstriction and water retention → increased venous pressures and eventually capillary pressures → extravasation of fluid into lungs (left-sided congestive heart failure leading to pulmonary edema), or chest and abdomen (right-sided congestive heart failure; pleural effusion and occasionally ascites).
- Increased venous pressure and volume = increased preload → structural changes in myocardial sarcomeres.
Cor pulmonale
- Right ventricular enlargement secondary to respiratory disease or high altitude disease.
- In some cases may be the first indicator that severe pulmonary disease exists.
- Increased pulmonary vascular resistance → pulmonary hypertension.
- This increases the work that the right heart has to do → compensatory hypertrophy of the right ventricle.
- If hypertension persists then right-sided failure ultimately develops.
Timecourse
- Depends on underlying heart disease; most heart conditions (except cardiac tamponade), are progressive and eventually cannot be controlled.
Diagnosis
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed Papers
- Recent references from PubMed And VetMedResource.
- Christopher R, Malherbe, Marquard J, David E et al (2012) Right ventricular hypertrophy with heart failure in Holstein heifers at elevation of 1,600 meters. J Vet Diag Invest 24 (5), 867-77.
- Buczinski S, Francoz D, Fecteau G & DiFruscia R (2010) Heart disease in cattle with clinical signs of heart failure: 59 cases. CN Vet J 51 (10), 1123–1129 PubMed.