15, 80, 81
Use it to rank the techniques by how much they actually unload, not to choose between them on outcome. The ranking by unloading power (micro-axial pump and septostomy highest, balloon pump lowest) is close to the inverse of the ranking by safety, and the device with the strongest observational mortality signal - the balloon pump - has the weakest measured haemodynamic effect.
Within-patient before-and-after haemodynamics; no study had a control group
DOI 10.1177/0267659119897478
Mechanical left ventricular unloading - intra-aortic balloon pump (1 study), micro-axial blood pump (2), left ventricular venting (1), atrial septostomy (4)
No control group in any included study. Few studies per category. Heterogeneous designs. No information on intra-patient correlation coefficients. Literature dominated by case reports with publication bias favouring successful outcomes. CRITICALLY: no dose-response association was demonstrated between the degree of unloading achieved and mortality - the physiological effect is measured, its clinical value is not.
Left ventricular unloading produced a significant reduction in preload: standardised mean difference -1.05 (95% CI -1.24 to -0.86); ratio of means 0.60 (0.47 to 0.76), a 40% reduction. By technique: micro-axial pump SMD -1.11 (-1.55 to -0.68), ratio of means 0.58 (0.39 to 0.86); atrial septostomy SMD -1.22 (-1.47 to -0.96), ratio of means 0.54 (0.36 to 0.83); intra-aortic balloon pump a non-significant 21% reduction; left ventricular venting 22%. Authors conclude the effect may be most pronounced for micro-axial blood pump and atrial septostomy.
Adults on veno-arterial extracorporeal life support for refractory cardiogenic shock; 8 studies, 149 patients. Perfusion 2020;35(7):664-671. Retrieved in full.