Pulmonary Hypertension and Heartworm Lecture Review

Flashcards providing vocabulary terms and definitions related to pulmonary hypertension and heartworm disease in veterinary patients, based on lecture notes.

Pulmonary Hypertension (PH)

Increased pressure within the pulmonary vasculature, a hemodynamic and pathophysiologic state present in various cardiovascular, respiratory, and systemic diseases, typically a secondary syndrome in veterinary patients.

Strong clinical findings suggestive of PH in dogs

Syncope (especially with exertion or activity) without another identifiable cause, respiratory distress at rest, activity or exercise terminating in respiratory distress, and right-sided heart failure (cardiogenic ascites).

Possible clinical findings suggestive of PH in dogs

Tachypnea at rest, increased respiratory effort at rest, prolonged postexercise or post-activity tachypnea, cyanotic or pale mucous membranes.

Group 1 PH (Pulmonary arterial hypertension)

PH types including idiopathic, heritable, drug/toxin-induced (e.g., fenfluramine), congenital shunting (L→R increasing flow), and vasculitis.

Group 2 PH (Left cardiac disease)

Pulmonary hypertension caused by conditions such as DCM, myocarditis, MMVD, and aortic/MV stenosis.

Group 3 PH (Respiratory disease)

Pulmonary hypertension associated with interstitial lung disease (fibrosis, EBP, neoplasia, chronic pneumonia), and chronic bronchitis.

Group 4 PH (Pulmonary thromboembolism)

Pulmonary hypertension caused by blood clots obstructing pulmonary vessels.

Group 5 PH (Dirofilaria or Angiostrongylus)

Pulmonary hypertension resulting from parasitic infections like heartworm or lungworm.

Group 6 PH

Pulmonary hypertension with multifactorial or unclear underlying causes.

Pulmonary Hypertension (as a condition)

Not a disease per se, but rather a hemodynamic and pathophysiologic state present in a wide variety of diseases.

Untested strategies to decrease PH progression

Exercise restriction, prevention of contagious respiratory pathogens (vaccination) and parasitic disease (chemoprophylaxis), avoidance of pregnancy, high altitude/air travel, and nonessential wellness procedures/elective surgery requiring general anesthesia.

Sildenafil (for PH treatment)

A PDE5 inhibitor prescribed for all Group 3 PH (primary respiratory disease) if clinical signs or echocardiogram support diagnosis, and potentially for other groups depending on chronicity and clinical signs.

Common diagnostic tests for PH

Hematologic and biochemical studies, coagulation/D-dimer evaluation, heartworm tests, arterial blood gas/pulse oximetry, bronchoscopy/bronchoalveolar lavage, lung aspirate, central venous pressure, pulmonary scintigraphy, pulmonary CT scan, and pulmonary angiography.

Heartworm Disease

One of the many causes of pulmonary hypertension.

Heartworm Life Cycle (patency)

The period where adult worms in the pulmonary arteries begin to produce offspring (microfilariae), typically occurring 6 to 7 months post-infection.

Villous myointimal proliferation

The typical lesion in the pulmonary arteries caused by adult heartworms, leading to increased resistance to pulmonary flow and vascular damage, contributing to pulmonary hypertension.

Heartworm Diagnosis methods

Identification of microfilaria (routine blood smear, Modified Knott’s), serologic antigen testing (test of choice), antibody testing (for cats), chest radiographs, echocardiogram, and ECG.

Antigen test (for heartworm)

The test of choice for diagnosing heartworm disease in dogs, detecting adult female heartworm antigen.

Wolbachia

Rickettsial intracellular, gram-negative bacteria that have a symbiotic relationship with Dirofilaria immitis, assisting with development and increasing fecundity; doxycycline pretreatment is used to kill these bacteria.

Complications of Heartworm Disease

Chronic hepatic congestion/cirrhosis, glomerulonephritis (Ag-Ab complex), thromboembolic disease, anaphylaxis to dying worms, and Caval syndrome.

Heartworm Disease Stage 1

Characterized by no clinical signs, normal radiographic findings, and normal clinical pathology.

Heartworm Disease Stage 2

Clinical signs include occasional cough, mild fatigue; radiographic findings show right ventricular enlargement (RVE), pulmonary artery enlargement (PAE), +/- mild interstitial opacity; minimal changes in clinical pathology.

Heartworm Disease Stage 3

Clinical signs include persistent respiratory symptoms, prominent fatigue, weight loss; radiographic findings show RVE, right atrial enlargement (RAE), PAE, diffuse perivascular and interstitial opacity; clinical pathology may include anemia, elevated ALT/ALP, thrombocytopenia, and proteinuria.

Heartworm Disease Stage 4 (Caval Syndrome)

An acute collapse/critical state due to a very high worm burden causing obstruction of right heart filling, leading to hemolytic anemia and DIC, often associated with a grave prognosis.

"Slow" Kill Method (Heartworm Treatment)

A treatment strategy involving monthly preventative doses of macrocyclic lactones and doxycycline (10mg/kg PO BID for 1 month every 3 months), typically over 2+ years.

"Fast" Kill Method (Heartworm Treatment)

Adulticide therapy using melarsomine (Immiticide) with either a 2-dose or 3-dose protocol to eliminate adult heartworms rapidly.

Heartworm Preventatives

Medications (oral, injectable, topical) containing active ingredients like ivermectin, milbemycin oxime, moxidectin, or selamectin, used to prevent heartworm infection by killing larval stages.

Feline Heartworm Disease prevalence

Typically 5 to 20% of canine prevalence, frequently amicrofilaremic, and characterized by small worm burdens (1-3 worms), making diagnosis more challenging.

Feline Heartworm Disease clinical signs

Often very similar to symptoms observed in feline asthma.

Feline Heartworm Diagnosis

Often requires a combination of antigen test, antibody test, and radiographs due to low worm burden and infrequent microfilaria in affected cats.

Eosinophilic pneumonitis (feline heartworm)

A common pulmonary inflammatory response seen in feline heartworm disease.

Sudden death (feline heartworm)

A common severe complication in feline heartworm disease, often attributed to embolic disease.