Canine pulmonary hypertension, Part 1: An in-depth review of its pathophysiology and classifications - Veterinary Medicine
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Canine pulmonary hypertension, Part 1: An in-depth review of its pathophysiology and classifications
This complex syndrome is not as uncommon as we once thought. Understanding its pathophysiology and classification schemes—both clinical and functional—will help you better manage this condition in your patients.


VETERINARY MEDICINE


FUNCTIONAL CLASSIFICATION


Table 2: WHO Functional Classification Scheme of Pulmonary Hypertension
While the clinical classification scheme groups pulmonary hypertension patients into classes based on the underlying cause of pulmonary hypertension, the functional classification scheme groups these patients into classes based on the severity of pulmonary hypertension-induced clinical signs (Table 2). This schematic was also developed at the 1998 WHO Evian meeting and is used in human medicine to help determine when to institute therapy, to decide which treatments may be most beneficial, and to provide an objective treatment goal.25 Although not explicitly evaluated in dogs, the information can be easily extrapolated from people to dogs.

Functional class I

This class includes patients with pulmonary hypertension that do not suffer any decrease in physical activity and can exercise without signs of dyspnea, fatigue, chest pain, or syncope.

Functional class II

Class II patients are comfortable at rest but suffer a mild decrease in activity associated with dyspnea, fatigue, chest pain, or syncope.

Functional class III

These patients have pulmonary hypertension that results in marked limitations in physical activity and have severe dyspnea, fatigue, chest pain, or syncope even with minimal activity. These patients are comfortable at rest.

Functional class IV

The final class includes patients with pulmonary hypertension that are unable to participate in physical activity, and any activity leads to severe signs. These patients are symptomatic at rest and have right-sided heart failure secondary to pulmonary hypertension.

CONCLUSION

Canine pulmonary hypertension is a complex condition caused by an imbalance in pulmonary arterial vasoconstriction and vasodilation and is associated with enhanced platelet actions and vascular remodeling. Patients with pulmonary hypertension may be classified into clinical groups based on the underlying cause of disease and into functional groups based on the severity of signs. Ultimately, the classification schemes should help practitioners diagnose pulmonary hypertension, formulate an effective treatment plan, and evaluate a patient's prognosis.

Rebecca L. Quinn, DVM, DACVIM (internal medicine)
Department of Cardiology
Angell Animal Medical Center
350 S. Huntington Ave.,
Boston, MA 02130

Justin G. Williams, DVM, DACVIM (cardiology)
VCA Animal Care Center of Sonoma County
6470 Redwood Drive
Rohnert Park, CA 94928


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Source: VETERINARY MEDICINE,
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