Veterinary Medicine: Pulmonary Hypertension Quiz

Pulmonary Hypertension Overview

• Pulmonary hypertension (PH) is characterized by abnormally increased pressure within the pulmonary vasculature, specifically a mean pulmonary arterial pressure (PAP) greater than mmHg.
• The lecture outlines six classifications of PH, various diagnostic methods, and treatment strategies.
• Understanding the anatomy and pathophysiology of PH, along with its classifications, severity definition, signs, symptoms, diagnosis, and treatment, are crucial learning objectives of the lecture.

Anatomy Review

• Diagrams are provided, labeling parts of the heart and lungs' vasculature.
• Note the labels and their locations within the diagram which indicate the systems of the heart.

What is Pulmonary Hypertension?

• PH involves abnormally elevated pressure within pulmonary blood vessels.
• Mean pulmonary arterial pressure (PAP) is a critical measurement in determining the severity of PH.

How Do We Actually Measure The PAP?

• Non-invasive diagnostic imaging (like echocardiography) is used to evaluate and diagnose PH..
• The tricuspid valve's function and blood flow during systole are factors in assessing and diagnosing animals with PH.

Peak Tricuspid Regurgitation Velocity (TRVmax)

• Doppler echocardiography measures this velocity.
• TRVmax helps evaluate systolic pulmonary artery pressure.
• A simplified Bernoulli equation identifies the TRPG (Tricuspid Regurgitation Pressure Gradient).

Severity of PH

• The severity levels of PH are correlated with the TRPG (Tricuspid Regurgitation Pressure Gradient) measurement in mmHg.
• Mild, Moderate, and Severe PH have varying ranges of TRPG.

Pathophysiology

• The provided diagram highlights the flow of blood through the heart and lungs.
• Pressure and oxygen levels in different parts of the pulmonary system are correlated and are part of the pathophysiology.

Clinical Presentation

• Age and breed can affect a dog's likelihood of developing PH.
• Young dogs might experience shunts (like PDA).
• Older dogs might have pre-existing conditions that contribute, such as pulmonary fibrosis.
• Small breeds and brachycephalic breeds carry more risk of specific conditions.
• Geographic location is a contributing factor—parasites are more prevalent in certain areas

Clinical Symptoms

• Symptoms like tachypnea (rapid breathing), respiratory effort, and cyanosis/pale mucous membranes could imply PH.
• Key signs like syncope, respiratory distress during activity, and right-sided heart failure are more strongly suggestive of PH.

Physical Exam

• Physical examination may reveal cyanosis, respiratory abnormalities, murmurs (such as in the mitral or tricuspid valves), and other signs specific to PH.
• Respiratory patterns assess the respiratory system's overall function.
• Jugular vein distension and other physical findings aid in diagnosis.

Thoracic Radiographs

• Radiographs (X-rays) are a critical diagnostic tool for visualizing the thorax and detecting possible signs of PH.

Treatments

• Three main treatment goals are outlined to improve diagnoses and outcomes.
• General advice is given to reduce risks related to PH, regardless of cause.
• Specific therapies to treat underlying causes of PH are varied, but can consist of medication and surgery.

What Causes Pulmonary Hypertension?

• The presented data organizes the causes of PH into six categories (Groups 1-6).
• Each group has distinct causes of PH, influencing the treatment and diagnostic approaches.
• The categories outlined in the slides are; Group 1, Group 2, Group 3, Group 4, Group 5, and Group 6.

Group 1: Pulmonary Arterial Hypertension

• This group encompasses idiopathic, heritable, drug-induced, and congenital cardiac shunts as causes.
• Key diagnostic methods include echocardiogram and other radiographic analysis.
• Treatments include shunt closure or sildenafil.

Group 2: PH Due to Left Heart Disease

• Common causes include left ventricular dysfunction, dilated cardiomyopathy, valvular disease (like myxomatous mitral valve disease), and aortic stenosis.
• Diagnostic procedures involve echocardiogram and thoracic radiographs.
• Therapies like Pimobendan, ACE inhibitors, and furosemide are used, with sildenafil discouraged in this group.

Group 3: Respiratory Disease and/or Hypoxia

• Causes include obstructive airway diseases (like chronic bronchitis, tracheal/bronchial collapse), pulmonary parenchymal diseases, and feline asthma.
• Hypoxic pulmonary vasoconstriction explains the circulatory response to poor oxygen supply.
• Treatment focuses on managing underlying respiratory issues and considers the use of sildenafil in some conditions.

Group 4: Thromboembolic Disease

• Causes include acute or chronic pulmonary embolism resulting from blood clots.
• Signs are secondary to existing hypercoagulable states (like Cushing's syndrome, infectious disease).
• Diagnosis involves thoracic radiographs and CT angiography for a comprehensive evaluation.
• Treatment includes anticoagulants (e.g., clopidogrel) and management of underlying conditions

Group 5: Parasitic Disease

• Heartworm (Dirofilaria immitis) and lungworm (Angiostrongylus vasorum) are cited as common causes.
• Diagnosis involves tests like the Snap 4Dx.
• Treatments commonly involve deworming agents like moxidectin or fenbendazole; and sildenafil if needed to reduce PH symptoms.

Group 6: Multifactorial

• This group features various underlying causes, including masses compressing pulmonary arteries and other disorders with unknown mechanisms.
• Diagnosis may involve detecting two or more underlying pathologies from Groups 1-5.
• Treatments aim at reducing or eliminating multiple causes.