Appendix C — Abbreviations and Glossary

Abbreviations

Glossary of terms defined in this book

Acute cor pulmonale — RV/LV end-diastolic area ratio > 0.6 with septal dyskinesia, in the setting of acute RV pressure overload.

Annulus reversus — septal e′ exceeding lateral e′; a feature of constrictive pericarditis, and counter-intuitive because normal tissue Doppler is usually reassuring.

Coandă effect — the tendency of an eccentric regurgitant jet to hug the adjacent chamber wall, making it appear small on colour Doppler while carrying a large regurgitant volume.

Coumadin ridge — the muscular ridge between the left atrial appendage and the left upper pulmonary vein, with a bulbous "Q-tip" tip; a classic thrombus mimic.

Dimensionless index — the ratio of subvalvular to transvalvular velocity or VTI; independent of LVOT diameter measurement and therefore immune to the squared-error problem.

Fluid responsiveness — a predicted increase in stroke volume of ≥ 10–15% following an increase in preload. A property of the Frank–Starling position, not an indication for fluid.

Fluid tolerance — the capacity to accommodate an increase in preload without pathological pulmonary or systemic venous congestion.

Harlequin (north–south) syndrome — differential hypoxaemia during peripheral VA-ECMO, where poorly oxygenated native ejection perfuses the upper body while oxygenated circuit blood perfuses the lower.

Low-flow state — stroke volume index < 35 mL/m². The condition under which every stenosis gradient under-states severity.

Pressure recovery — downstream re-conversion of kinetic energy to pressure, causing Doppler to report a higher gradient than simultaneous catheterisation.

Pseudo-PEA — organised, coordinated myocardial contraction on ultrasound in a patient with no palpable pulse; profound shock rather than electromechanical dissociation, and with a materially better prognosis.

Pseudo-severe aortic stenosis — a valve area that appears severe at low flow but opens above 1.0–1.2 cm² when flow is augmented; the myocardium, not the valve, is the problem.

RV spiral of death — RV dilatation → rising wall stress and falling coronary perfusion pressure → RV ischaemia → worse RV function → septal shift → falling LV output and systemic pressure → further fall in RV coronary perfusion.

Unmasking — the appearance of previously concealed myocardial depression when a vasopressor restores arterial elastance in vasoplegic shock. Not vasopressor toxicity.

Ventriculo-arterial decoupling — Ea/Ees above the normal range (> 1.5), indicating that the ventricle is operating inefficiently against its arterial load.

Washing jet — the small, characteristic transprosthetic regurgitant jet designed into mechanical prostheses to prevent stasis; a normal finding.

Weaning-induced pulmonary oedema — hydrostatic pulmonary oedema precipitated by the simultaneous rise in preload, afterload and oxygen demand at the transition to spontaneous breathing; reverses within minutes of resuming support, which is why it is missed.