Pulmonary Hypertension
Description:
- Hypertension is defined as the pathological elevation of arterial blood pressure.
- There are two main types of hypertension, systemic hypertension (affects the systemic circulation) and pulmonary hypertension (affects the pulmonary circulation).
- Blood pressure in veterinary patients is not measured routinely; therefore hypertension is usually only diagnosed after clinical signs become apparent.
Description:
- Pulmonary hypertension=increase in pulmonary arterial pressure
There are two types of pulmonary hypertension:
1. Primary pulmonary hypertension=idiopathic pulmonary hypertension (Contributing factors: Drugs, Toxins, Genetic Predisposition and Infections)
2. Secondary pulmonary hypertension=pulmonary hypertension resulting from an identifiable underlying condition
- cor pulmonale=right sided heart failure resulting from pulmonary hypertension
- Pulmonary thromboembolism from neoplasia, heart worm disease, and other factors can cause cor pulmonale by blocking the pulmonary vessels with emboli leading to increased pulmonary arterial pressures and ultimately right sided heart failure.
- The hypoxic conditions at high elevations or animals with chronic airway disease contribute to pulmonary hypertension through hypoxia-induced vasoconstriction.
Signalment
- Some diseases predispose animals to secondary pulmonary hypertension.
Genetics & Breed Predisposition: Brachycephalic Dogs (chronic obstructive pulmonary disease); Small breeds (mitral endocardiosis); West Highland White Terriers (Pulmonary Fibrosis)
Diagnosis
History & Clinical Signs
- Signs of right sided heart failure:
-Exercise Intolerance
-Dyspnoea
-Coughing
-Syncope
-Cyanosis
-Abdominal Distension
-Distended Jugular Veins
Physical Exam
- Depends on underlying conditions
-Heart Murmur (Mitral or tricuspid regurgitation)
-Gallop Rhythm
-Increased Lung Sounds
-Splitting of S2 heart sounds
Laboratory Findings
-Arterial Blood Gases (Hypoxemia): If there are low oxygen conditions
-Complete Blood Count (Eosinophilia): If parasitic involvement; Serology or Fecal Baermann tests confirm parasitic involvement
-Biochemistry (Hyperglobulinemia): If Chronic Inflammation
-Urinalysis (Proteinuria): If Systemic Disease
Radiography
DV view
-Left atrial and ventricular enlargement
-Pulmonary arterial enlargement
-Congested pulmonary veins
-Signs of pulmonary disease
Electrocardiography
-Right ventricular hypertrophy (Deep S-waves)
-Signs of myocardial hypoxia (ST segment abnormalities)
Echocardiography
-Calculation of pulmonary arterial pressures
-Enlargement of right-side of heart
-Visualize mitral or tricuspid regurgitation
Treatment
Treat the underlying conditions:
- Treat right sided heart failure
- Treat pulmonary thromboembolism with heparin and then warfarin
- Treat chronic obstructive pulmonary disease
Prognosis
-Depends on the disease condition and ability to control it
-Poor when pulmonary damage is irreversible
- Caused by left-to-right vascular shunts or increased resistance of the pulmonary vascular system
- In animals, it is most commonly a sequel of widespread fibrosis in the lung or chronic bronchitis or bronchiolitis which stimulates hypertrophy in the walls of small arteries
- Severe prolonged pulmonary hypertension leads to cor pulmonale, right-sided heart failure secondary to primary lung disease