Page 708 - Small Animal Clinical Nutrition 5th Edition

Cardiovascular Disease 735

diagnosis. As an example, a small-breed dog may be admitted
Table 36-1. Functional classes of heart failure.*
VetBooks.ir abnormal breath sounds with crackles and a holosystolic mur- Class I. The asymptomatic patient
with moderate obesity, cough, tachypnea, exercise intolerance,
mur loudest over the mitral valve. It is important that this
Heart disease is detectable (cardiac murmur, dysrhythmia), but
patient be evaluated thoroughly to determine whether the cause the patient is not overtly affected and does not demonstrate
clinical signs of heart failure.
of the clinical signs is: 1) chronic bronchitis, 2) early heart fail- a. Heart disease is detectable but no signs of compensation
ure, 3) obesity or 4) a combination of these conditions. are evident, such as volume or pressure overload ventricu-
Human patients with heart disease and failure are categorized lar hypertrophy.
b. Heart disease is detectable in conjunction with radiograph-
according to functional and structural schemes. The functional ic or echocardiographic evidence of compensation, such
scheme is based on the clinical signs and symptoms evident at as volume or pressure overload ventricular hypertrophy.
rest and during exercise (New York Heart Association function- Class II. Mild to moderate heart failure
Clinical signs of heart failure are evident at rest or with mild
al classes). Members of the International Small Animal Cardiac exercise and adversely affect the quality of life. Typical clinical
Health Council popularized a functional classification scheme signs include exercise intolerance, cough, tachypnea, mild res-
that is applicable to veterinary patients (Table 36-1) (ISACHC, piratory distress and mild to moderate ascites. Hypoperfusion at
rest is generally not present.
1994). Although patients with heart disease may follow an Class III. Advanced heart failure
orderly progression though a functional classification, animals Clinical signs of CHF are immediately evident. These clinical
may change classifications in both directions–e.g.,from Class III signs include respiratory distress (dyspnea), marked ascites,
profound exercise intolerance and hypoperfusion at rest. In the
or IV to Class II or III following therapy, or from Class I to most severe cases, the patient is moribund and suffers from
Class III or IV following a salty meal. cardiogenic shock.
In 2001, the American College of Cardiology (ACC) and *Adapted from International Small Animal Cardiac Health
Council. In: Recommendations for the Diagnosis of Heart
the American Heart Association (AHA) developed a staging Disease and the Treatment of Heart Failure in Small Animals.
scheme for heart failure patients emphasizing the progressive Academy of Veterinary Cardiology, 1994.
nature of the diseases that cause heart failure. This scheme has
been adapted as follows for veterinary use (Keene and
Bonagura, 2009): The ACC/AHA scheme provides a framework for thinking
• Stage A–patients at high risk for the development of heart about heart disease that is more analogous to the clinical
failure, but without currently apparent structural heart approach to cancer, i.e., the identification of patients who are
abnormalities (e.g., cavalier King Charles spaniels, boxers, known to be at risk for cancer and who might benefit from
Doberman pinschers and other animals belonging to more intensive screening to identify disease at an early stage
breeds, families or demographic groups known to be pre- (Stage A); the identification and treatment of patients with in-
disposed to heart disease). situ disease (Stage B); and the identification and treatment of
• Stage B–patients with a structural heart abnormality, but patients with established (Stage C) or widespread (Stage D)
without past or current symptoms of heart failure (e.g., disease. As our knowledge of the pathophysiology of heart dis-
patients with an asymptomatic murmur of mitral regurgi- ease and the progression of heart disease to heart failure
tation). expands, there is hope that early pharmacologic and/or nutri-
• Stage C–patients with a structural abnormality and current tional intervention (often possible before the onset of clinical
or previous clinical signs of heart failure (this stage includes signs in heart disease) might significantly affect the eventual
all patients that have experienced clinical signs of heart fail- course of disease and survival in an individual patient.
ure, and they stay in this stage despite resolution of their Currently, however, there are essentially no well-defined, effec-
clinical signs with standard therapy). tive therapies that prevent or delay the onset of heart disease or
• Stage D–patients with clinical signs of heart failure that failure in either dogs or cats.
have become refractory to standard treatment (defined In assessing the nutritional status of patients with cardiovascu-
practically as standard doses of furosemide, angiotensin- lar disease, overall body condition is the most important indica-
converting enzyme [ACE] inhibitor and pimobendan). tor of nutritional status and it appears to be an important, inde-
The ACC/AHA staging system emphasizes that progressive pendent prognostic indicator. As will be discussed later, obesity
structural abnormalities of the heart underlie the pathogenesis causes cardiovascular changes that can complicate the manage-
of heart failure. This scheme is meant to encourage a program ment of cardiovascular disease, but in dogs and cats, significant
of client education and heart failure management that supports weight loss is a far more common problem after the onset of
early screening for heart disease and provides a loosely defined heart failure. Although treatment of obesity is occasionally nec-
plan for therapeutic intensification, including nutritional inter- essary in the management of patients with significant cardiovas-
vention, as heart disease progresses.This staging system further cular disease, it is relatively uncommon that clinically significant
departs from functional classifications in that while a patient obesity coexists with life-threatening cardiovascular disease in
can still progress suddenly from Stage B to Stage C (or D, for dogs and cats. Cachexia is a syndrome of severe wasting seen
example, if a previously asymptomatic dog with chronic valvu- clinically in a variety of diseases, especially chronic heart failure,
lar heart disease experiences a ruptured mitral valvular chorda cancer and acquired immunodeficiency syndrome.Cachexia is an
tendineae), that path cannot be traveled in reverse. additional risk factor in people with heart failure; loss of lean