IntroductionExercise test with direct measurement of central hemodynamics is used in assessment of patients with dyspnea, where the association between cardiac output (CO) and pulmonary capillary ...wedge pressure (PCWP) may provide insight in the hemodynamic adaption to exercise in different cardiac conditions. Thus the aim was to compare changes in CO relative to PCWP during exercise in patients with pressure overload (aortic stenosis (AS)), volume overload (primary mitral regurgitation (MR)), diastolic dysfunction after myocardial infarction (AMI), and healthy controls.MethodsA symptom limited supine bicycle test with right heart catheterization was performed in 175 patients and healthy volunteers aged>50 years (40 patients with AS (LVEF≥50%, aortic valve area<1 cm and peak aortic valve velocity>3.5 m/s), 62 patients with recent AMI and diastolic dysfunction (LVEF>45%, E/e′ >8 -and LA volume index>34 ml/m), 42 patients with primary MR (LVEF>55%, effective regurgitant orifice>0.3 cm) and 31 healthy subjects. PCWP was assessed at rest, submaximal and peak exercise and CO determined using thermodilution. CI was calculated as CO divided by body surface area.ResultsAll exercised to anaerobic threshold (lactate at peak exercise 6.0±2.8 mmol/l, with AMI patients having higher values than remaining groups). PCWP increased with exercise, mostly in AMI and AS (change from rest 21±7 mmHg and 20±5 mmHg respectively) compared with MR patients (15±7mmHg) and controls (14±7 mmHg), p<0.001. CI increased most in controls (5.5±1.5 l/min/m) and AMI patients (4.9±1.5 l/min/m) and least in AS patients (3.7±1.3 l/min/m), p=0.001. The relationship between increase in CI and PCWP was linear in all groups with a steeper slope for all patients groups compared with controls (p<0.05) and steeper slope in AS and AMI patients than MR patients (p<0.002), Figure.ConclusionsThe relationship between PCWP and CI was linear with distinct slopes according to underlying disorder. Both pressure and volume overloaded ventricles achieved lower increases in CO compared to AMI and healthy subjects. In the pressure overloaded ventricle a higher filling pressure was required to achieve adequate increase in CI compared with the volume loaded ventricle.
