Echocardiographic Assessment in a Patient with Vasoreactive Pulmonary Hypertension

Case Presentation: A 30-year old woman with no significant medical history presented to the hospital with breathlessness and fatigue. An electrocardiogram (Mac 5500HD, General Electric, Fairfield, CT, USA) showed right ventricular (RV) hypertrophy. A chest x-ray demonstrated central pulmonary arterial dilatation with pruning of the peripheral blood vessels. An echocardiogram (iE33, Philips, Amsterdam, The Netherlands) indicated the presence of severe pulmonary hypertension (PHTN). There was no evidence of intracardiac shunt, leftsided valvular lesions or elevation in left-sided filling pressures. A workup for the etiology of the PHTN including routine biochemistry, hematology, thyroid function, serological testing for connective tissue disease, human immunodeficiency virus and hepatitis B virus was nonrevealing. A ventilation/perfusion scan and high-resolution computed tomography (Discovery CT 750HD, General Electric) of the chest failed to demonstrate an underlying etiology for the PHTN. At right heart catheterization, the following pressures were recorded: pulmonary artery (PA) 87/ 41 (mean 58 mmHg), aorta 100/52 (mean 68 mmHg), mean right atrium (RA) 5 mmHg and mean pulmonary capillary wedge (PCW) 8 mmHg. Pulmonary vascular resistance (PVR) and systemic vascular resistance (SVR) were 20 and 25 Wood units, respectively, with a cardiac output (CO) of 2.4 L/min. After challenge with inhaled nitric oxide (NO) at a dose of 20 ppm, the following pressures were recorded: PA 51/21 (mean 31 mmHg), aorta 152/49 (mean 87 mmHg), mean RA 2 mmHg and mean PCW 5 mmHg. PVR and SVR decreased to 6.5 and 19 Wood units, respectively, and CO increased to 4.2 L/min following NO. The patient was given the diagnosis of idiopathic pulmonary arterial hypertension with positive response to acute vasodilator challenge as manifested by a significant drop in mean PA pressure and PVR and increase in CO. The patient was treated with sustained-release nifedipine and later with long-acting diltiazem; however, she was poorly compliant without demonstrable drug-related side effects. She was then treated with inhaled iloprost, a prostanoid, together with sildenafil, a phosphodiesterase type-5 inhibitor. She used iloprost 4 times daily instead of the recommended 6–9 times daily. Its use was associated with a sense of well-being that lasted for <1 hour. A follow-up transthoracic echocardiogram (iE33) was performed before, at 10 minutes and at 45 minutes following the inhalation of iloprost. PVR was calculated using the formula 10 9 (peak TR velocity/RV outflow time-velocity integral) + 0.16. Left and right ventricular volumes were reconstructed from 3-dimensional (3D) images using commercially available analysis software (Tomtec Imaging Systems GmbH, Munich, Germany). Right ventricular strain and strain rate (SR) were derived using the same software. The index of RV myocardial performance (Tei index) was calculated by adding the isovolumic contraction and relaxation times divided by the ejection time. At 10 minutes, profound hemodynamic and structural alterations occurred. Acute reduction in PA pressure and PVR was noted with decrease in RA and RV size and filling pressures, increase in left-sided chambers’ size, improvement in biventricular systolic function and CO and significant decrease in the severity of tricuspid regurgitation (TR) (Figs. 1 and 2, movie clips 1–4). In addition, spectral and tissue Doppler parameters, RV systolic indices and time intervals showed parallel improvement. Peak RV longitudinal and radial Address for correspondence and reprint requests: Bahaa M. Fadel, King Faisal Specialist Hospital & Research Center, Heart Institute, PO Box: 3354, MBC # 16, Riyadh 11211, Saudi Arabia. Fax: 966-14427482; E-mail: bmfadel@yahoo.com