The response to inhaled nitric oxide in patients with pulmonary artery hypertension is not masked by baseline vasodilator use

Can Inhaled Nitric Oxide Response Predict Tolerance to Therapies and Survival in Patients With Combined Precapillary and Postcapillary Pulmonary Hypertension?

Inhaled nitric oxide (iNO) relaxes the pulmonary circulation and variably increases the left ventricular preload and pulmonary artery wedge pressure (PAWP)-hemodynamic information that may help guide treatment decisions and assess prognosis in patients with combined precapillary and postcapillary pulmonary hypertension (PH). We included consecutive patients with combined precapillary and postcapillary PH (mean pulmonary artery pressure >20 mm Hg, PAWP >15 mm Hg, and pulmonary vascular resistance [PVR] >2 Woods unit [WU]) who underwent right-sided cardiac catheterization with iNO at the Cleveland Clinic Pulmonary Vascular Disease program between 2017 and 2022. We included 104 patients with baseline PAWP and PVR of 22.2 ± 4.2 mm Hg and 6.1 ± 3.2 WU, respectively. Pulmonary arterial hypertension (PAH) with postcapillary component and PH left heart disease with precapillary component were identified in 27 (26%) and 77 patients (74%), respectively. No side effects were noted during the administration of iNO. During iNO, the PVR decreased 1.1 ± 1.4 WU and the PAWP increased 1.3 ± 3.7 mm Hg. A more pronounced increase in PAWP with iNO was associated with a decrease in PVR (R -0.35, p <0.001) and increase in stroke volume (R 0.20, p = 0.046). Tolerance to PAH-specific medications, overall survival, and heart failure hospitalizations were not significantly associated with the change in PAWP or PVR with iNO. In conclusion, in patients with combined precapillary and postcapillary PH, iNO challenge is safe and caused a significant decrease in PVR, with an increase in PAWP. The changes in PAWP and PVR during iNO administration were not associated with tolerance to PAH-specific medications, heart failure-related hospitalization, or survival.

Clinical Presentation, Differential Diagnosis, and Vasodilator Testing of Pulmonary Hypertension

Clinicians should be cognizant of the symptoms and risk factors associated with pulmonary hypertension (PH). While known PH poses significant therapeutic challenges, occult PH carries the added potential for unanticipated complications when treating concurrent medical illnesses. PH may occur with underlying medical conditions and risk factors or may occur de novo as idiopathic pulmonary arterial hypertension (IPAH). Symptoms of PH are frequently attributed to more common conditions, and their nonspecific nature and insidious onset may lead to delay in presentation, evaluation, and diagnosis. Initial symptoms are dyspnea, fatigue, chest pain, and palpitations. Lower extremity edema, presyncope, and syncope are symptoms of more advanced disease. Thorough evaluation of symptoms and identification of patients with risk factors for PH are critical in making a timely diagnosis. History and physical examination can identify patients with suspected PH. Further testing is necessary for definitive diagnosis, classification, assessment of severity, and guiding therapeutic decisions.

Calcium channel blockers for pulmonary arterial hypertension

BACKGROUND

Pulmonary arterial hypertension (PAH) is one of several forms of pulmonary hypertension: a chronic disease of the pulmonary vasculature. The mean age at diagnosis is around 50 years old, with increasing prevalence in people over 70 years old (10% to 17%). The median survival to be approximately seven years with one-, three-, five-, and seven-year survival rates from time of diagnostic right-sided heart catheterization were 85%, 68%, 57%, and 49%, respectively. Several studies showed that calcium channel blockers (CCBs) reduce right ventricular hypertrophy and improve long-term haemodynamics in PAH.

OBJECTIVES

To evaluate the clinical efficacy and harms of CCBs for people with PAH.

SEARCH METHODS

The search strategy was provided by the Cochrane Airways Group Trials Search Co-ordinator. The following databases were searched from their inception until September 2014: the Cochrane Airways Group Register of Trials (CAGR); the Cochrane Central Register of Controlled Clinical Trials (CENTRAL) (The Cochrane Library,Issue 8 2014); MEDLINE (1948 to September 2014); EMBASE (1974 to September 2014); ClinicalTrials.gov; WHO trial portal; the Chinese Biomedical Databases (1979 to September 2014); CNKI: the Chinese Journals Full Text Database (1979 to September 2014), the Chinese Journals Full Text Database Century Journals (1979 to September 2014), the Chinese Doctoral Degree Thesis Full Text Database (1979 to September 2014), the Chinese Outstanding Master Degree Thesis Full Text Database (1979 to September 2014); VIP Database (1989 to September 2014) and WANFANG Database (1993 to September 2014). No language restriction was applied.

SELECTION CRITERIA

Fully published randomized controlled trials (RCTs) comparing CCBs with placebo or other treatment, or comparing CCBs as an adjunct to other treatments with other treatments alone, in patients with PAH.

DATA COLLECTION AND ANALYSIS

We used standard methods expected by Cochrane.

MAIN RESULTS

We found one RCT to include in this review but it was published only in abstract form with no data for evaluation.

AUTHORS' CONCLUSIONS

Currently, as there is lack of valid evidence, the efficacy and safety of CCBs is unproven in the treatment of PAH. However, the search strategy used for this review did identify four controlled clinical trials without randomization, three of which suggested treatment with CCBs may be beneficial in PAH. No adverse side effects of CCBs were reported. Confirmation of these findings by RCTs is recommended.

Modified INOvent for delivery of inhaled nitric oxide during cardiac MRI

BACKGROUND

The aim of this study was to assess the feasibility of delivering NO through a modified system to allow clearance of the magnetic field and thus compatibility with cardiac magnetic resonance (CMR). Nitric oxide (NO) is an inhalational, selective pulmonary vasodilator with a wide range of applications in a variety of disease states, including diseases that affect the right ventricle. Accurate assessment of dynamic changes in right ventricular function necessitates CMR; however, delivery of NO is only possible using equipment that is not magnetic resonance imaging (MRI) compatible (INOvent delivery system, Ohmeda, Inc., Madison, WI, USA).

METHODS

The INOvent delivery system was modified by using 35 ft. of standard oxygen tubing to allow NO delivery through an electrical conduit and into the MRI suite. The concentrations of oxygen (O(2)), nitrogen dioxide (a harmful byproduct, NO(2)) and NO were measured in triplicate using the built-in electrochemical analyzer on the INOvent. After confirmation of safety, the system was used to administer drug to a patient x, and dynamic MRI measurements were performed.

RESULTS

When the standard INOvent was set to administer 40 ppm of NO, the mean/standard deviation of gas delivered was as follows: NO: 42/0 ppm; NO(2): 0.3/0.1 ppm; and O(2): 93/0 ppm. In comparison, the gas delivery of the modified INOvent was follows: NO: 41/0 ppm; NO(2): 0.5/0 ppm; and O(2): 93.7/0.6 ppm. During administration to an index patient with severe pulmonic insufficiency (PI), a measurable reduction in PI was observed by CMR.

CONCLUSIONS

Nitric oxide can be administered through 35 ft. of standard oxygen tubing without significantly affecting dose delivery. This technique has potential application in patients with right-sided structural heart disease for determination of dynamic physiological changes.

Pulmonary hypertension related to left-sided cardiac pathology

Pulmonary hypertension (PH) is the end result of a variety of diverse pathologic processes. The chronic elevation in pulmonary artery pressure often leads to right ventricular pressure overload and subsequent right ventricular failure. In patients with left-sided cardiac disease, PH is quite common and associated with increased morbidity and mortality. This article will review the literature as it pertains to the epidemiology, pathogenesis, and diagnosis of PH related to aortic valve disease, mitral valve disease, left ventricular systolic and diastolic dysfunction, and pulmonary veno-occlusive disease. Moreover, therapeutic strategies, which focus on treating the underlying cardiac pathology will be discussed.