Pulmonary hypertension in left heart disease: A review

Soluble guanylate cyclase stimulator riociguat and phosphodiesterase 5 inhibitor sildenafil ameliorate pulmonary hypertension due to left heart disease in mice

BACKGROUND

Presence of pulmonary hypertension (PH) and right ventricular dysfunction worsens prognosis in patients with chronic heart failure (CHF). Preclinical and clinical studies suggest a role for the impaired nitric oxide (NO)-soluble guanylate cyclase (sGC)-cyclic guanosine monophosphate (cGMP) signaling pathway in both PH and CHF. Hence, we examined the effects of the NO-sGC-cGMP pathway modulation by the PDE5 inhibitor sildenafil or sGC stimulator riociguat on pulmonary hemodynamics and heart function in a murine model of secondary PH induced by transverse aortic constriction.

METHODS

C57Bl/6N mice were subjected to transverse aortic constriction (TAC) for 6weeks to induce left heart failure and secondary PH and were subsequently treated with either sildenafil (100mg/kg/day) or riociguat (10mg/kg/day) or placebo for 2weeks.

RESULTS

Six weeks after surgery, TAC induced significant left ventricular hypertrophy and dysfunction associated with development of PH. Treatment with riociguat and sildenafil neither reduced left ventricular hypertrophy nor improved its function. However, both sildenafil and riociguat ameliorated PH, reduced pulmonary vascular remodeling and improved right ventricular function.

CONCLUSIONS

Thus, modulation of the NO-sGC-cGMP pathway by the PDE5 inhibitor sildenafil or sGC stimulator riociguat exerts direct beneficial effects on pulmonary hemodynamics and right ventricular function in the experimental model of secondary PH due to left heart disease and these drugs may offer a new therapeutic option for therapy of this condition.

Under pressure: pulmonary hypertension associated with left heart disease

Pulmonary hypertension (PH) associated with left heart disease (PH-LHD) is the most common type of PH, but its natural history is not well understood. PH-LHD is diagnosed by right heart catheterisation with a mean pulmonary arterial pressure ≥25 mmHg and a pulmonary capillary wedge pressure >15 mmHg. The primary causes of PH-LHD are left ventricular dysfunction of systolic and diastolic origin, and valvular disease. Prognosis is poor and survival rates are low. Limited progress has been made towards specific therapies for PH-LHD, and management focuses on addressing the underlying cause of the disease with supportive therapies, surgery and pharmacological treatments. Clinical trials of therapies for pulmonary arterial hypertension in patients with PH-LHD have thus far been limited and have provided disappointing or conflicting results. Robust, long-term clinical studies in appropriate target populations have the potential to improve the outlook for patients with PH-LHD. Herein, we discuss the knowledge gaps in our understanding of PH-LHD, and describe the current unmet needs and challenges that are faced by clinicians when identifying and managing patients with this disease.

Pulmonary hypertension due to left heart disease is associated with multiple unmet medical needshttp://ow.ly/TFET8

Pressure reflection in the pulmonary circulation by echocardiography in patients with left heart disease indicates reactive pulmonary hypertension

OBJECTIVES

The two hemodynamic profiles in left heart disease (LHD) with pulmonary hypertension (PH), passive PH with increased pulmonary venous pressure and reactive PH with increased pulmonary vascular resistance (PVR > 3 Wood units, WU), are difficult to distinguish non-invasively. We hypothesized that echocardiographic signs of pressure reflection (PR) in the pulmonary circulation can be used to diagnose reactive PH.

MATERIAL AND METHODS

The study comprised 122 patients divided into three groups: patients without PH (No PH, n = 61), patients with LHD, PH and normal PVR (passive PH, n = 29) and patients with LHD, PH and increased PVR (reactive PH, n = 32). Echocardiography and right heart catheterization were performed within 24 h. Three parameters were selected related to PR [the acceleration of flow in the right ventricular outflow tract (RVOT), the interval and the augmentation of pressure between peak RVOT flow and peak RV pressure]. Cutoff values aiming at ruling in (high positive likelihood ratio, PLR) and ruling out (low negative likelihood ratio, NLR) increased PVR were determined using receiver operator characteristic (ROC) curves.

RESULTS

The proportions of the patients with PH and PVR > 3 WU were 50% and 29%. Twenty-one percent had both increased pulmonary capillary wedge pressure and PVR. The area under the ROC curve for the PR parameters was 0.82-0.89. The PLR with ruling in cutoff values ranged from 4.7 to 9.4. The NLR with ruling out cutoff values ranged from 0.20 to 0.12.

CONCLUSIONS

Echocardiographic assessment of PR in patients with LHD can be used to identify or exclude reactive PH.

Impact of net atrioventricular compliance on clinical outcome in mitral stenosis

BACKGROUND

Net atrioventricular compliance (Cn) has been reported to be an important determinant of pulmonary hypertension in mitral stenosis (MS). We hypothesized that it may be useful in assessing prognosis because Cn reflects hemodynamic consequences of MS. To date, limited data with an assumed Cn cutoff have indicated the need for larger prospective studies. This prospective study was designed to determine the impact of Cn on clinical outcome and its contribution to pulmonary pressure in MS. In addition, we aimed to identify a cutoff value of Cn for outcome prediction in this setting.

METHODS AND RESULTS

A total of 128 patients with rheumatic MS without other significant valve disease were prospectively enrolled. Comprehensive echocardiography was performed and Doppler-derived Cn estimated using a previously validated equation. The end point was either mitral valve intervention or death. Cn was an important predictor of pulmonary pressure, regardless of classic measures of MS severity. During a median follow-up of 22 months, the end point was reached in 45 patients (35%). Baseline Cn predicted outcome, adding prognostic information beyond that provided by mitral valve area and functional status. Cn ≤4 mL/mm Hg best predicted unfavorable outcome in derivation and validation sets. A subgroup analysis including only initially asymptomatic patients with moderate to severe MS without initial indication for intervention (40.6% of total) demonstrated that baseline Cn predicted subsequent adverse outcome even after adjustment for classic measures of hemodynamic MS severity (hazard ratio, 0.33; 95% confidence interval, 0.14-0.79; P=0.013).

CONCLUSIONS

Cn contributes to pulmonary hypertension beyond stenosis severity itself. In a wide spectrum of MS severity, Cn is a powerful predictor of adverse outcome, adding prognostic value to clinical data and mitral valve area. Importantly, baseline Cn predicts a progressive course with subsequent need for intervention in initially asymptomatic patients. Cn assessment therefore has potential value for clinical risk stratification and monitoring in MS patients.

The imaging of pulmonary hypertension

Pulmonary hypertension (PH) is the remarkable hemodynamic consequence of widespread structural and functional changes within the pulmonary circulation. Elevated pulmonary vascular resistance leads to increased mean pulmonary arterial pressure and, ultimately, right ventricular dysfunction. PH carries a poor prognosis and warrants timely and accurate diagnosis for appropriate intervention. The 2008 Dana Point classification system provides the categorical framework currently guiding therapy and surveillance. Radiologic imaging is an essential tool in the detection and diagnostic evaluation of patients with PH. Echocardiography, ventilation-perfusion scintigraphy, multidetector computed tomography, and cardiac magnetic resonance imaging provide insights into vascular morphology, pulmonary parenchymal status, cardiac function, and underlying etiology of the disorder. Emerging techniques of functional pulmonary and cardiac imaging hold great promise for the assessment and monitoring of these patients in the future.