The Role of Pulmonary Vasodilators in Pulmonary Hypertension







Age: 26 years


Gender: Male


Occupation: Systems engineer


Working diagnosis: Pulmonary arterial hypertension



HISTORY


The patient had been diagnosed with a hemodynamically insignificant VSD at age 2 years. No further follow-up had been arranged, and his upbringing was unremarkable.


The patient was well until age 18 when he developed breathlessness, palpitations, and chest pain. After 3 years of symptoms, at age 21, he sought attention and a workup ensued.


TTE showed no VSD, but the right heart was enlarged. The estimated RV systolic pressure was 110 mm Hg. A right heart catheterization measured a mean pulmonary artery pressure of 97 mm Hg. Secondary causes of PAH were excluded. He was diagnosed with IPAH.


The patient was offered heart-lung transplant but declined. He also refused prostanoid therapy and was subsequently started on oxygen, warfarin, and sildenafil.


Initially, the patient noted marked improvement on sildenafil. At reassessment 3 months later, his myocardial oxygen consumption had increased from 15.2 mL/kg/min (predicted value, 42.9%) to 20.3 mL/kg/min, and he was able to manage 12 minutes of the Bruce protocol.


At age 26, the patient was admitted to his local hospital with a productive cough, breathlessness, coryzal symptoms, left-sided pleuritic chest pain, and groin pain. Antibiotics were started at his local hospital, and he was transferred to a tertiary care facility for further care.





Comments: PAH is one of five causes of pulmonary hypertension (as outlined in the current classification from the 2003 Third World Symposium on Pulmonary Arterial Hypertension) and is defined as a mean pulmonary artery pressure higher than 25 mm Hg at rest or higher than 30 mm Hg with exercise (in the context of an elevated pulmonary vascular resistance > 3 Wood units or > 240 dyn/sec/cm −5 ). Known secondary causes include connective tissue disease, congenital left-to-right shunts, HIV, and drugs and toxins. Otherwise, it is termed idiopathic or familial (IPAH or FPAH, respectively). In this patient, the absence of a VSD now makes it unlikely that this was related to his pulmonary hypertension.


PAH is rare, and carries a poor prognosis (predicted median survival for IPAH patients is 2.8 years). Although the condition is more common in women, men are also affected. Symptoms are nonspecific, and patients may appear deceptively well. Clinical detection therefore can be difficult and result in delay of appropriate treatment.


The velocity of the regurgitant jet through the tricuspid valve allows an assessment of RV systolic pressure (a value of > 2.8 m/sec is considered elevated). However, the predictive accuracy of the peak velocity diminishes in the setting of PAH.


Calcium-channel blockers are used only in the small group of IPAH patients who demonstrate a positive response to short-acting vasodilators. Right heart failure is a contraindication to their use. Oxygen is used to reduce the pulmonary vasoconstrictor effect of hypoxia. Warfarin is used to attenuate the risks of in situ thrombosis and pulmonary thromboembolism (both resulting from stasis, procoagulability, and endothelin damage). Intravenous epoprostenol is the candidate of choice in IPAH given its rapid onset of action and favorable evidence base. It aims to supplement circulating prostacyclin levels, which have been found, with nitric oxide levels, to be reduced. Its effects are mediated via an intracellular second messenger (cAMP), and include vascular effects beyond vasodilatation. These reduce both platelet aggregation and vascular smooth muscle proliferation. Unfortunately, it requires long-term central venous access for continuous therapy. Attendant risks of infection and delivery failure are sources of morbidity and mortality. Prostanoids can be also be inhaled or given subcutaneously, though these forms have their own disadvantages.


As the suggested treatment options were not acceptable to the patient, sildenafil was used at the clinician’s discretion. Sildenafil (given orally) inhibits phosphodiesterase 5, preventing breakdown of cGMP and indirectly that of cAMP. Sildenafil has a short half-life and must be taken three times a day. This augments the action of nitric oxide and prostacyclin. Current guidelines record a low level of evidence and weak recommendation (level of evidence C) for the use of sildenafil in patients with PAH who have failed or are not candidates for other therapy.





CURRENT SYMPTOMS


The patient noted a recent substantial deterioration in his exercise tolerance.


WHO class: III





Comments: Often the World Health Organization classification is used as a rough gauge of the functional capacity of the patient, and is based on the NYHA format. It correlates with disease severity and prognosis and is useful in identifying those who require more advanced treatments.





CURRENT MEDICATIONS





  • Sildenafil 25 mg orally three times daily



  • Warfarin (target INR of 2–3)






Comments: The recommended dose of sildenafil for PAH is 20 mg by mouth three times daily, as a dose-response study did not show any further benefit at 50 or 100 mg.





PHYSICAL EXAMINATION





  • BP 126/60 mm Hg, HR 70 bpm, oxygen saturation 96% on room air



  • Height 169 cm, weight 65 kg, BSA 1.75 m 2



  • Neck veins: JVP was visible at the ears with the patient sitting upright. Prominent A-waves and CV-waves were noted.



  • Lungs/chest: Bronchial breathing and reduced percussion noted at the left base with a pleural rub in the same area



  • Heart: The rhythm was regular. There was a palpable left parasternal lift, a grade 1/6 pan-systolic murmur, and a grade 2/4 early diastolic murmur. Both murmurs were augmented on inspiration.



  • Extremities: Edema from the foot to the thighs, as well as over the sacrum



PERTINENT NEGATIVES


There was no abdominal guarding, and no evidence of connective tissue disease.





Comments: Neck vein distension reflects right heart failure and significant tricuspid regurgitation.


The lung exam suggests a respiratory cause for both the patient’s pain and his deterioration.


Cardiac findings are consistent with severe RV pressure overload and systolic RV impairment with tricuspid and pulmonary regurgitation, and right heart failure.





LABORATORY DATA













































Leukocyte count 6.0 × 10 9 /L (4.4–10.1)
Hemoglobin 16.1 g/dL (13.0–17.0)
Hematocrit/PCV 51% (41–51)
MCV 89 fL (83–99)
Platelet count 140 × 10 9 /L (150–400)
Sodium 132 mmol/L (134–145)
Potassium 4.1 mmol/L (3.5–5.2)
Creatinine 0.97 mg/dL (0.6–1.2)
Blood urea nitrogen 4.2 mmol/L (2.5–6.5)
Albumin 2.3 g/dL (35–50)
CRP 106 mg/L (0–10)
GGT 89 IU/L (11– 51)
ALT 372 IU/L (8–40)

Only gold members can continue reading. Log In or Register to continue

Sep 11, 2019 | Posted by in CARDIOLOGY | Comments Off on The Role of Pulmonary Vasodilators in Pulmonary Hypertension
Premium Wordpress Themes by UFO Themes