Severe pulmonary hypertension (PAH) is confirmed by documenting an elevated TR velocity and right heart compensatory changes. The estimated systolic pulmonary arterial pressure in this case was >90mmHg, with normal being <25mmHg. This led to severe hypertrophy and dilation of the right heart (indicating severe right-heart pressure overload). Clinical signs of weakness, heavy breathing, cyanosis, and syncope are attributed to severe PAH. Trace MR was also present, however the left heart dimensions were normal to small, indicative of dehydration.

The underlying genesis of PAH is poorly understood in cases other than heartworm infestation, though it occurs with increased frequency in a variety of forms of chronic lung disease and in patients with idiopathic pulmonary fibrosis. If not performed, a heartworm antigen test is always recommended. Given a chronic cough and collapsing trachea in this case, chronic airway disease with an acute secondary exacerbating insult (infectious or inflammatory) was suspected. Patients with this degree of PAH and pulmonary disease can develop right-sided congestive heart failure (ascites), debilitating cyanosis, labored breathing and exertional syncope if poorly controlled.

Given the recent onset of worsening respiratory signs in this case, the most common cause is an infectious or inflammatory insult causing a decline in already poor oxygenation status. A PTE cannot be ruled out. A Radiologist review of radiographs, as well as repeat films for comparison are extremely beneficial in these cases, particularly in light  of echo  findings. Coverage with broad spectrum pulmonary antibiotic (fluoroquinolone) was recommended, in addition to aggressive vasodilation using pimobendan and sildenafil. Lasix should be discontinued in these cases as diuretics can actually further reduce preload in cases of debilitating PAH and worsen clinical signs. Cautious fluid therapy may be helpful, due to hypotension likely due to volume depletion. Continued hospitalization for oxygen support and IV antibiotics may be necessary until stabilized.

Once stable, use of theophylline and/or taper course of anti-inflammatory steroids can also be beneficial in these cases, to treat exertional dyspnea or acute flare ups and decrease the inflammatory component as much as possible. PRN use of cough suppressants may also be beneficial. Unfortunately the prognosis overall is poor, however I am hopeful we can provide some medical relief going forward assuming the patient can be stabilized through the current crisis.