Single arterial occlusion to locate resistance in patients with pulmonary hypertension

Abstract

The purpose of this study was to determine the site of increased resistance using the arterial occlusion technique in patients with severe pulmonary hypertension.Pulmonary vascular resistance was partitioned in arterial and venous components based on double exponential fitting analysis of the pulmonary artery pressure decay curve: after balloon occlusion in 36 patients with pulmonary arterial hypertension (PAH); at baseline and during the inhalation of 20 parts per million of nitric oxide (NO); in four patients with chronic thromboembolic pulmonary hypertension; and in two patients with pulmonary veno-occlusive disease.In the patients with PAH, at baseline, mean pulmonary artery pressure was 56¡2 mmHg (mean¡SE), with an arterial component of resistance of 63¡1%. Inhaled NO did not change the partition of resistance. The arterial component of resistance amounted on average to 42% and 77% in the patients with veno-occlusive disease and the patients with thromboembolic pulmonary hypertension, respectively. However, the partitioning of resistance did not discriminate between these three diagnostic categories.The occlusion technique may help to locate the predominant site of increased resistance in patients with severe pulmonary hypertension, but does not allow for a satisfactory differential diagnosis on an individual basis.

Occlusion pressure analysis role in partitioning of pulmonary vascular resistance in CTEPH

“…A separate, blinded investigator performed a biexponential fitting of the pressure decay curve between the moment of occlusion and the PAOP, with normalisation to the mPAP. This has been previously described and is used here to derive occlusion pressure (Poccl) [5,8]. Rup (upstream pressure) was calculated as follows: Rup % 5 100 6 (mPAP -Poccl) / (mPAP -PAOP).…”

Hemodynamic assessment of pulmonary hypertension

“…The measurement of the effective Pcap requires the analysis of a PAOP decay curve after balloon occlusion through different methods: (1) the visual inspection method, where the inflection point is designated as the capillary pressure; (2) a single exponential curve is fitted to the average arterial occlusion pressure decay in the segment between 0.3 s and 2 s after time 0 (occlusion); and (3) a better fit of PAOP decay curves after balloon occlusion is obtained with a biexponential function. This method of calculation led to lower Pcap values than found using a mono-exponential fitting ( Figure 3) [6,8,11] . When the PA is occluded, there is a rapid decrease in Table 2 Recommendations for right heart catheterization blood flow as the occluded downstream PA discharges its blood volume sequentially into the pulmonary capillaries across the arterial resistance and then into the pulmonary veins across the venous resistance.…”

“…The measurement of an effective Pcap, requires the analysis of a PAP decay curve after balloon occlusion, as will be described later [8,9] . A hemodynamic study was recently conducted in 3920 patients with PH, and the reliability of PAOP to distinguish PAH and PH associated with LV disease compared to LV end-diastolic pressure (the gold standard of LV preload) was analyzed.…”

Pulmonary veno-occlusive disease: advances in clinical management and treatments

“…By definition, true capillary pressure (Pc) and measured PCWP are normal (<15 mmHg) in idiopathic PAH. Since Pc measurement is not suitable for clinical application, PCWP is currently the most frequently used method for estimating Pc in a broad range of clinical and/or experimental conditions [57,58]. By contrast, in PVOD experimental conditions, the post-capillary obstruction leads to an elevated Pc without any increase in PCPW [59,60].…”

“…Measurement of the Pc may theoretically be useful in PVOD; the principle of Pc pressure measurement is extrapolated from a canine model whereby the pressure decay following balloon occlusion is mathematically analyzed to represent the emptying of the capillary compartment [61]. Interestingly, Fesler et al showed showed that this method helps to locate the site of predominantly increased pulmonary vascular resistance in severe PAH and that patients displaying PVOD may have higher Pc than PAH patients using this method [57,58].…”