High Prevalence of Occult Pulmonary Venous Hypertension Revealed by Fluid Challenge in Pulmonary Hypertension

Abstract

Background Determining the cause for pulmonary hypertension (PH) is difficult in many patients. Pulmonary arterial hypertension (PAH) is differentiated from pulmonary venous hypertension (PVH) by a wedge pressure (PWP) >15 mmHg in PVH. Patients undergoing RHC for evaluation of PH may be dehydrated and have reduced intravascular volume, potentially leading to a falsely low measurement of PWP and an erroneous diagnosis of PAH. We hypothesized that a fluid challenge during RHC would identify occult pulmonary venous hypertension (OPVH). Methods and Results We reviewed the results of patients undergoing fluid challenge in our PH database from 2004-2011. Baseline hemodynamics were obtained and repeated following infusion of 0.5 liters of normal saline over 5-10 minutes. Patients were categorized as OPVH if PWP increased to >15 mm Hg after fluid challenge. Baseline hemodynamics in 207 patients met criteria for PAH. Following fluid challenge, 46 patients (22.2%) developed a PWP >15 mm Hg and were re-classified as OPVH. OPVH patients had a greater increase in PWP compared to PAH patients, p<0.001, and their demographics and comorbid illnesses were similar to PVH patients. There were no adverse events related to fluid challenge. Conclusions Fluid challenge at the time of RHC is easily performed, safe, and identifies a large group of patients diagnosed initially with PAH, but for whom OPVH contributes to PH. These results have implications for therapeutic trials in PAH and support the routine use of fluid challenge during RHC in patients with risk factors for PVH.

Noninvasive identification of left-sided heart failure in a population suspected of pulmonary arterial hypertension

“…The flip side is the recognition that some patients with heart failure with preserved ejection fraction, in particular those on diuretic medications, may have a wedge pressure of ⩽15 mmHg and an elevated PVR at the time of RHC. This phenomenon may be recognised with volume loading [15] or invasive exercise testing [38]. Even though the final diagnosis was reached after discussion by an expert panel and volume loading was routinely performed at high normal wedge pressures (12-15 mmHg), we cannot exclude that an occasional patient was misclassified.…”

“…We used the following decision rule to discriminate between precapillary PH and PH secondary to LHF [14]. If wedge pressure was >15 mmHg at rest or increased >15 mmHg after 500 mL of saline infusion, the diagnosis of PH secondary to LHF was made [15]. If no reliable wedge was obtained, LVEDP was measured.…”

Pulmonary hypertension: Classification and pathobiology

“…Recent studies suggest that occult left heart failure is common in patient with pulmonary hypertension [11] and misclassification of these patients might result in use of "PHtarget"therapies without evidence of benefit. The application of a fluid bolus (e.g., 250 or 500 ml sa line) during right heart catheterisation to identify these patients is not defined and routine application of this test cannot be recommended at the moment.…”

Pulmonary hypertension associated with left heart and lung diseases

“…In patients with HFpEF who typically have concentric left ventricular remodelling with a small left ventricular cavity and a steep end-diastolic pressure-volume relationship, relatively small changes in left ventricular volume may lead to significant changes in filling pressures [17]. Thus, a fluid challenge (500 ml of saline over 5 minutes) may be needed to diagnose PH-LHD in the context of HFpEF [16,18]. There is also evidence that exercise right heart catheterisation may help to gain a better definition of the haemodynamic profile of patients with HFpEF.…”