Acute heart failure
Introduction
- Although many patients suffering from cardiovascular disease are identified during routine examination or present with mild clinical signs, a subset will present on an emergency basis with severe, life-threatening congestive heart failure.
- These patients often require aggressive therapy and intensive monitoring to achieve a successful outcome.
- Despite their critical status at presentation many will survive for prolonged periods if the acute episode is successfully managed.
Acute presentation
- Patients with decompensated heart failure often present with signs of congestive and/or low output heart failure.
- Severe congestive heart failure Heart: congestive heart failure:
- Profound increase in respiratory rate (tachypnea) and effort (dyspnea).
- Orthopnea.
- Anxiety/disorientation.
- Weakness.
- Cardiogenic shock (severe forward failure) Shock: cardiogenic:
- Syncope/collapse.
- Weakness and/or lethargy.
- Cold extremities.
Age predisposition
- Most are adult cats suffering from cardiomyopathy, either hypertrophic Heart: hypertrophic cardiomyopathy or restrictive Heart: restrictive cardiomyopathy.
- Young cats with large left to right shunting lesions, (ie ventricular septal defects Ventricular septal defect ) or with atrioventricular valve dysplasia Atrioventricular valve dysplasia may present with decompensated heart failure.
Breed/Species predisposition
- Hypertrophic cardiomyopathy (HCM) Heart: hypertrophic cardiomyopathy: certain breeds are predisposed including:
- Maine Coon Maine Coon.
- American Shorthairs American Shorthair.
- Persians Persian longhair.
- In addition, many cats with DCM Heart: dilated cardiomyopathy (DCM) are domestic short or longhairs.
- No breed predilections have been recognized in cats with restrictive cardiomyopathy (RCM) Heart: restrictive cardiomyopathy.
Cost considerations
- Moderate costs involved with:
- Diagnostics.
- Hospitalization.
- Oxygen therapy.
- Intravenous drugs.
- Intensive monitoring.
- Intensely managed case of acute heart failure may cost around $700 to $1000 (UK: £400 - £600).
Inform owners that cardiovascular medications and periodic rechecks will be required throughout the remainder of the pet's life.
Special risks
- Any event contributing to stress and further decompensation.
Patients with decompensated heart failure are very poor anesthetic candidates and every attempt should be performed to avoid anesthesia and stress.
Pathogenesis
Etiology
- Etiologies behind development of feline HCM and RCM are not totally understood.
- A mutation in the myosin binding protein-C gene has been associated with HCM in a family of Maine Coons.
- Nutritional taurine deficiency Taurine deficiency is well-described cause of feline myocardial failure (dilated cardiomyopathy). Adequate dietary taurine supplementation found in virtually all cat foods has greatly reduced the incidence this disease. Currently, the occasional cases of feline DCM that are detected are usually not taurine related, do not respond to supplementation, and are idiopathic with respect to etiology.
Pathophysiology
- Following the initial cardiac insult and a reduction in cardiac output there are short-term compensatory mechanisms that become activated to facilitate circulatory homeostasis, including:
- Sympathetic nervous system.
- Renin-angiotensin-aldosterone system (RAAS).
- Release of arginine-vasopressin.
- Renal sodium and water retention.
- Feline cardiomyopathies (HCM, RCM) are primarily diseases of diastolic dysfunction, in which concentric hypertrophy or myocardial fibrosis limits the ability of the heart to relax during diastole.
- Feline dilated cardiomyopathy (DCM Heart: dilated cardiomyopathy (DCM)) is similar in pathophysiology to canine DCM, in which there is progressive loss of systolic function.
- Ultimately pulmonary capillary pressures rise promoting the development of pulmonary edema Lung: pulmonary edema, pleural effusion Pleural effusion, or ascites (rare in cats) while pronounced increase in afterload diminishes effective forward blood and increases myocardial oxygen demands.
Timecourse
- Time until development of decompensated heart failure is difficult to predict based on today's diagnostic modalities.
- Some patients live for years with significant cardiovascular disease but never develop nor require treatment for heart failure.
- Predisposing factors that may quickly shift a patient with compensated heart failure to a decompensated state include:
- The development of arrhythmias Heart: dysrhythmia, especially atrial fibrillation Atrial fibrillation.
- Abrupt discontinuation of prescribed medications.
- Stress.
- Corticosteroid administration.
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.
- Ferasin L (2009) Feline myocardial disease. 1: Classification, pathophysiology and clinical presentation. J Feline Med Surg 11 (1), 3-13 PubMed.
- Schober K E, Maerz I (2006) Assessment of left atrial appendage flow velocity and its relation to spontaneous echocardiographic contrast in 89 cats with myocardial disease. J Vet Intern Med 20 (1), 120-130 PubMed.
- Cesta M F, Baty C J, Keene B W et al (2005) Pathology of end-stage remodeling in a family of cats with hypertrophic cardiomyopathy. Vet Patho 42 (4), 458-467 PubMed.
- Baty C J (2004) Feline hypertrophic cardiomyopathy: an update. Vet Clin North Am Small Anim Pract 34 (5), 1227-1234 PubMed.
- Côté E, Manning A M, Emerson D et al (2004) Assessment of the prevalence of heart murmurs in overtly healthy cats. JAVMA 225 (3), 384-388 PubMed.
- Pion P D (2004) Traditional and nontraditional effective and noneffective therapies for cardiac disease in dogs and cats. Vet Clin North Am Small Anim Pract 34 (1), 187-216 PubMed.
- Rush J E, Freeman L M, Fenollosa N K et al (2002) Population and survival characteristics of cats with hypertrophic cardiomyopathy: 260 cases (1990-1999). JAVMA 220 (2), 202-207 PubMed.
Other sources of information
- Bryn Tennant Small Animal Formulary (2002) 4th edn. BSAVA. pp 211-212.
- Kittleson M (2000) Therapy of heart failure. In: Textbook of Veterinary Internal Medicine.5th edn. Ed S J F E Ettinger. Philadelphia: WB Saunders Company. pp 713-737.
- Sisson D & Kittleson M (1999) Management of Heart Failure: Principles of Treatment, Therapeutic Strategies, and Pharmacology. In: Textbook of Canine and Feline Cardiology: Principles and Clinical Practice. 2nd edn. Eds P R Fox, D Sisson and N S Moise. Philadelphia: WB Saunders. pp 216-250.