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Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.

Cardiorenal syndrome

Cardiology · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

RapidFull
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Escalate

Refractory pulmonary oedema, severe hyperkalaemia, severe metabolic acidosis, uraemic complications, anuria/rapidly worsening AKI or shock requires immediate senior HF, renal and critical-care assessment; do not delay renal-replacement referral for an isolated creatinine threshold.

Synopsis

Interpret concurrent heart and kidney dysfunction by congestion, perfusion and time course, preserve beneficial heart-failure therapy where safe and recognise dialysis-level emergencies.

  • Cardiorenal syndrome describes bidirectional heart–kidney dysfunction; identify acute versus chronic change and whether congestion, low perfusion, drugs, sepsis or intrinsic renal disease dominates.
  • Raised venous pressure is a major renal insult in decompensated HF; a congested patient with rising creatinine may still need effective decongestion.
  • NICE does not recommend loop diuretics to treat AKI itself, but does recommend considering them for fluid overload or oedema while renal function is recovering or awaiting renal replacement.
  • Do not automatically stop ACE inhibitor/ARNI/ARB/MRA for every small creatinine rise; reassess volume, BP, potassium and the current NICE threshold/action plan.
  • Under NICE 2025, renal function and electrolytes are checked before ACEi/ARNI/ARB/MRA, 1–2 weeks after starting and each increment, every 3–6 months once stable and whenever renal function may be compromised.
  • A creatinine increase over 50% or potassium over 5.5 mmol/L on ACEi/ARNI/ARB/MRA requires prompt repeat assessment of BP, volume, renal function, potassium, nephrotoxins and interacting potassium sources, with dose adjustment/temporary withholding and HF–renal advice as indicated; do not silently continue or permanently stop every class.
  • With eGFR 45 mL/min/1.73 m² or less, use lower starting doses/smaller increments for HF combinations; at eGFR below 30, NICE advises the HF MDT to consider renal liaison.
  • NSAIDs, dehydration, infection, obstruction, contrast and unreviewed potassium supplements/salt substitutes are common preventable accelerants.

Key red flags

Low-output renal hypoperfusion

Hypotension, cool peripheries, oliguria and rising lactate/creatinine; diuretic escalation alone may worsen perfusion.

Hyperkalaemia toxicity

Weakness, conduction delay, bradyarrhythmia or broad-complex rhythm with high potassium is an immediate treatment emergency.

Renal-replacement indication

Refractory hyperkalaemia, acidosis, uraemic complications, fluid overload or pulmonary oedema despite medical treatment requires immediate nephrology/critical-care discussion.

Investigation priorities

01
Serial creatinine/eGFR, urea, sodium, potassium, bicarbonate and magnesiumFirst step

Define AKI trajectory and treatment toxicity.

Management branches

First-lineDefine physiology and cause

HF with worsening renal function

  1. Confirm baseline and AKI trajectory; record urine output, weight, BP, JVP/oedema, perfusion and recent medicines/illness.
  2. Check electrolytes, bicarbonate, urinalysis, ECG and cause-directed imaging; consider sepsis, obstruction, bleeding and nephrotoxins.
  3. Stop NSAIDs and other avoidable renal insults; adjust renally cleared medicines and treat infection/obstruction promptly.
  4. Discuss early with HF and renal teams when eGFR <30, AKI is progressive or treatment goals conflict.

Key medicines

FurosemideAcute overload: if loop-naive, commonly 20–40 mg IV initially; if already taking loop diuretic, use an initial IV dose higher than the pre-admission oral dose and titrate to response. Chronic doses are individualised to the lowest effective level.Monitor BP, urine, weight, creatinine, sodium, potassium and magnesium; high doses may be needed in CKD, but over-diuresis worsens hypoperfusion.
RamiprilHF commonly starts at 1.25 mg orally once daily and titrates toward 10 mg/day as tolerated; lower starting doses/smaller increments are considered when eGFR ≤45.Potassium, renal function and BP monitoring; an acute hold may be needed with severe AKI, hypotension or hyperkalaemia, but document review/restart. Avoid ACEi plus ARB/ARNI.
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Sources and review status5 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • NICE NG106: Chronic heart failure in adultsSeptember 2025 CKD dosing, renal/potassium monitoring and HF therapy.
  • NICE NG148: Acute kidney injuryAKI detection, diuretics, referral and renal-replacement indications.
  • NICE CG187: Acute heart failureIV decongestion and monitoring in acute HF.
  • MHRA: SGLT2 inhibitors during surgery or acute serious illnessTreatment interruption and ketone monitoring.
  • Furosemide injection SmPCLicensed acute oedema dosing.

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateRapid draftClinical stateAwaiting reviewJurisdictionUnited Kingdom