Clinical and hemodynamic factors in predicting response to fluid challenge during right heart catheterization

Pulmonary Hypertension Due to Left Heart Disease-A Practical Approach to Diagnosis and Management

Pulmonary hypertension (PH) due to left heart disease (LHD) is a frequent complication of heart failure (HF) and is associated with exercise intolerance, poor quality of life, increased risk of hospitalisations, and reduced overall survival. Since the recent Sixth World Symposium on Pulmonary Hypertension in 2018, there have been significant changes in the hemodynamic definitions and clinical classification of PH-LHD. PH-LHD can be subdivided into (1) isolated postcapillary PH (IpcPH) and (2) combined precapillary and postcapillary PH (CpcPH). This categorisation of PH-LHD is important because CpcPH shares certain pathophysiologic, clinical, and hemodynamic characteristics with pulmonary arterial hypertension and is associated with worse outcomes compared with IpcPH. A systematic approach using clinical history and noninvasive investigations is required in the diagnosis of PH-LHD. Right heart catheterisation with and without provocative testing is performed in expert centres and is indicated in selected individuals. Although the definition of IpcPH and CpcPH is based on measurements made with right heart catheterisation, distinguishing between these two entities is not always necessary. Despite strong evidence for medical therapy in patients with pulmonary arterial hypertension, those options have limited benefit in PH-LHD. Expert PH centres in Canada have been established to provide ongoing care for the more complex patient subgroups.

Impact of a volume challenge on haemodynamics and prognosis in patients with severe aortic stenosis

Aims

A volume challenge can unmask pulmonary hypertension (PH) and its mechanism. We evaluated the impact of a volume challenge on mean pulmonary artery pressure (mPAP) and mean pulmonary artery wedge pressure (mPAWP) and its prognostic implications in patients with severe aortic stenosis (AS) undergoing aortic valve replacement (AVR).

Methods and results

In 285 patients with severe AS (indexed aortic valve area 0.41 ± 0.13 cm²/m²), mPAP and mPAWP were measured before and after administration of 150 ± 58 mL of low‐osmolal or iso‐osmolal contrast. Following contrast, mPAP and mPAWP rose from 25 ± 10 and 16 ± 8 mmHg by 5 ± 4 and 4 ± 4 mmHg to 30 ± 11 and 20 ± 8 mmHg. There were 112 (39%) patients with pre‐contrast PH and 70 (40% of those without pre‐contrast PH) patients with post‐contrast PH only. Post‐contrast PH patients were intermediate between pre‐contrast PH and no PH in terms of AS severity, cardiac dysfunction, and haemodynamics. After a median follow‐up of 43 months post‐AVR, pre‐contrast PH patients had numerically the highest mortality driven by those with pre‐contrast combined pre‐capillary and post‐capillary PH (n = 35), while post‐contrast changes in mPAP and mPAWP were not related to mortality. Patients with any post‐contrast mPAWP > 18 mmHg had significantly higher mortality than those with post‐contrast mPAWP ≤ 18 mmHg,

Conclusions

In severe AS, a contrast challenge leads to post‐contrast PH in ~40% of patients without pre‐contrast PH. However, post‐contrast haemodynamic changes do not adversely affect outcomes in patients undergoing AVR. Post‐contrast PH represents an intermediate stage of ‘cardiac damage’, which may be attenuated or reversible after AVR.

A Fluid Challenge Test for the Diagnosis of Occult Heart Failure

A right heart catheterization with measurements of pulmonary artery wedge pressure (PAWP) may be necessary for the diagnosis of left heart failure as a cause of pulmonary hypertension or unexplained dyspnea. Diagnostic cutoff values are a PAWP of ≥ 15 mm Hg at rest or a PAWP of ≥ 25 mm Hg during exercise. However, accurate measurement of PAWP can be challenging and heart failure may be occult. Left heart catheterization, with measurement of left ventricular end-diastolic pressure, may also be indecisive. Measurements are then best repeated in stress conditions. Exercise is an option, but the equipment is not universally available, and interpretation can be difficult in patients with wide respiratory pressure swings. An alternative is offered by a fluid challenge. Studies have gathered data supporting infusion of 500 mL or 7 mL/kg saline and a PAWP of 18 mm Hg as a diagnostic cutoff. The procedure is simple and does not take much catheterization laboratory time. Combining echocardiography with invasive measurements may increase the diagnostic accuracy of diastolic dysfunction. Cardiac output after a fluid challenge may be of prognostic relevance.

Exercise and fluid challenge during right heart catheterisation for evaluation of dyspnoea

This prospective study compared exercise test and intravenous fluid challenge in a single right heart catheter procedure to detect latent diastolic heart failure in patients with echocardiographic heart failure with preserved ejection function. We included 49 patients (73% female) with heart failure with preserved ejection function and pulmonary artery wedge pressure ≤15 mmHg. A subgroup of 26 patients had precapillary pulmonary hypertension. Invasive haemodynamic and gas exchange parameters were measured at rest, 45° upright position, during exercise, after complete haemodynamic and respiratory recovery in lying position, and after rapid infusion of 500 mL isotonic solution. Most haemodynamic parameters increased at both exercise and intravenous fluid challenge, with the higher increase at exercise. Pulmonary vascular resistance decreased by –0.21 wood units at exercise and –0.56 wood units at intravenous fluid challenge (p = 0.3); 20% (10 of 49) of patients had an increase in pulmonary artery wedge pressure above the upper limit of 20 mmHg at exercise, and 20% above the respective limit of 18 mmHg after intravenous fluid challenge. However, only three patients exceeded the upper limit of pulmonary artery wedge pressure in both tests, i.e. seven patients only at exercise and seven other patients only after intravenous fluid challenge. In the subgroup of pulmonary hypertension patients, only two patients exceeded pulmonary artery wedge pressure limits in both tests, further five patients at exercise and four patients after intravenous fluid challenge. A sequential protocol in the same patient showed a significantly higher increase in haemodynamic parameters at exercise compared to intravenous fluid challenge. Both methods can unmask diastolic dysfunction at right heart catheter procedure, but in different patient groups.