It's the middle of the night (again). Your post-op cardiac patient looks awful, and the nurse says the cardiac output's low. Do you reach for a number — or do you look at the patient? In this episode Mike and Calum work through heart failure and mechanical circulatory support the way it actually plays out on a cardiothoracic ICU: how you know the output is low, what the devices really do, and how to escalate before it's too late. This is the intensive care half of the topic — the theatre half is a separate episode. We start with the idea that cardiac output is a clinical diagnosis, not a single figure — why venous sats and the Fick principle are clues rather than answers, and the picture that actually tells you the pump is failing (the tachycardia they're leaning on, the deranged liver enzymes and kidneys, the rising lactate, and the low-output gut that gets mistaken for an acute abdomen). We cover the pulmonary artery catheter — still the gold standard against a field of derived monitors — and how to float one, trace by trace. Then the machines. We give you the single most important habit on the unit — on any patient on support, always work out where the cannulas are and where the blood is going — and use it to walk through VA-ECMO (and why bypassing the heart and lungs means stagnation, clot, and a patient you usually can't wake), BiVADs (both sides supported, awake for weeks), and the ambulatory LVAD (why its flow is derived from power, why it's preload-dependent and afterload-sensitive, and why the shocked HeartMate patient in Emergency Department needs fluid before you pick up the phone). Finally, the practical half: escalating heart failure up the ladder — milrinone, then dopamine, then the balloon pump, and by then you're knocking on the door of a mechanical support assessment — plus inhaled nitric, a monitoring trap with the axillary return line, an honest look at ECMO-CPR, and why Harlequin syndrome is the signature limitation of peripheral VA-ECMO. Chapters (00:00) Cold open — 3am, and "the cardiac output's low" (01:00) Low cardiac output: why it's not a single number (03:30) The pulmonary artery catheter — gold standard, and how to float one (06:30) The golden rule: always find the cannulas — and VA-ECMO (08:30) BiVADs: supporting both sides, awake for weeks (10:00) LVADs and the HeartMate 3: flow is derived, not measured (12:10) Escalating heart failure: milrinone, dopamine, the balloon pump (14:40) The axillary return line — a monitoring trap (15:30) ECMO-CPR: the evidence and the criteria (17:20) Harlequin — the VA payoff (18:10) Wrap-up Key takeaways Cardiac output is a clinical diagnosis, not a number — venous sats and monitors are clues, not answers On any support device, always work out where the cannulas are and where the blood is flowing VA-ECMO bypasses heart and lungs — it clots, it's temporary, and you usually can't wake the patient; the elegant fix is femoral drainage with an axillary return LVAD flow is derived from power — it's preload-dependent and afterload-sensitive, so when in doubt, give fluid Milrinone → dopamine → balloon pump is the escalation ladder; a balloon pump means an MCS assessment is close Harlequin (differential hypoxaemia) is the signature limitation of peripheral VA-ECMO References / further reading Binanay C et al. ESCAPE trial: pulmonary artery catheter in advanced heart failure. JAMA 2005 Mathew R et al. DOREMI: milrinone vs dobutamine in cardiogenic shock. NEJM 2021 Mehra MR et al. MOMENTUM 3: HeartMate 3 (fully magnetically levitated LVAD). NEJM 2019 Ostadal P et al. ECMO-CS: early VA-ECMO in cardiogenic shock. Circulation 2023 Stub D et al. CHEER trial: refractory arrest, ECMO and cooling. Resuscitation 2015 Suverein MM et al. INCEPTION: ECPR vs conventional CPR in refractory out-of-hospital arrest. NEJM 2023 McDonagh TA et al. ESC Guidelines for the diagnosis and treatment of acute and chronic heart failure. Eur Heart J 2021 This podcast is for medical education for healthcare professionals. It is not clinical advice — always follow your local protocols and your regional cardiac / ECMO centre's guidance.
