Jørgen Frøkiær

Aim: Left ventricular filling pressure (preload) can be assessed by pulmonary wedge pressure (PCWP) during pulmonary arterial catherization (PAC). An emerging method (PICCO) can estimate preload by global end-diastolic volume (GEDV) and congestion as extravascular lung water content (EVLW). However, no reliable quantitative non-invasive methods are available. Hence, in a porcine model of pulmonary congestion, we evaluated EVLW and GEDV by positron emission tomography (PET). The method was applied in 35 heart failure (HF) patients and 9 healthy volunteers. Methods and Results: Eight pigs were studied. Pulmonary congestion was induced by a combination of beta-blockers, angiotensin-2 agonist and saline infusion. PAC, PICCO, computerized tomography and 15O-H2O-PET was performed. EVLW increased from 521±76 mL to 973±325 ml (p<0.001) and GEDV from 1068±170 ml to 1254±85 ml (p<0.001). 15O-H2O-PET measures of EVLW increased from 566±151 ml to 797±231 ml (p<0.001) and GEDV from 364±60 ml to 524±92 ml (p<0.001). Both EVLW and GEDV measured with PICCO and 15O-H2O-PET correlated (r2=0.40, p<0.001; r2=0.40, p<0.001, respectively). EVLW correlated with Hounsfield units (HU) (PICCO: r2=0.36 p<0.001, PET: r2=0.46 p<0.001) and GEDV with PCWP (PICCO: r2=0.20 p=0.01, PET: r2=0.29 p=0.002). In human subjects, measurements were indexed (I) for body surface area. Neither EVLWI nor HU differed between chronic stable HF patients and healthy volunteers (p=0.11, p=0.29) whereas GEDVI was increased in HF patients (336±66 ml/m2 vs. 276±44 ml/m2, p=0.01). Conclusion: The present study demonstrates that 15O-H2O-PET can assess pulmonary congestion and preload quantitatively. Hence, prognostic information from 15O-H2O-PET examinations should be evaluated in clinical trials.