After Cardiac Surgery

In depth

The one-page summary above is what the PDF prints. These sections go further.

What bypass does to the body

Bypass drains venous blood to a reservoir, oxygenates it and pumps it into the aorta, usually without pulsatility, while the heart is arrested with potassium cardioplegia behind an aortic cross-clamp. Blood contact with the circuit, surgical trauma and reperfusion of the heart and lungs set off a systemic inflammatory response (SIRS): complement and contact activation, activated neutrophils and endothelium, and a cytokine surge. At the bedside that means capillary leak, weight gain, vasodilation, fever in the first 24 to 48 hours that is usually inflammatory rather than infectious and, at the extreme, vasoplegia. The effects grow with bypass and cross-clamp times, so both belong in the handoff.

The crystalloid prime and cardioplegia dilute red cells, plasma proteins, fibrinogen and clotting factors, and a lower nadir hematocrit on bypass is associated with AKI and stroke. Platelets fall in number and function after circuit contact, hypothermia and heparin. After protamine, heparin can return from tissue stores (rebound), fibrinolysis stays active, and cold, acidosis and low ionized calcium slow clotting further, so bleeding after bypass is usually multifactorial.

Cardioplegia protects the myocardium incompletely: ischemia and reperfusion leave reversible dysfunction (stunning), worst about 4 to 8 hours after surgery and usually improving over the next day (IBCC), more slowly after a low preoperative EF or a long cross-clamp. Potassium can be high from cardioplegia or low after brisk diuresis; magnesium and ionized calcium are often low. Cool patients vasodilate as they rewarm and unmask hypovolemia. The lungs come off bypass atelectatic and leaky, the kidneys have had low-pressure nonpulsatile flow and hemolysis, and the brain has been exposed to emboli and air.

Arrival and the ICU handoff

Arrival is a high-risk transfer: the patient is cold, ventilated, on several infusions and wired by another team. Most units use two phases. First the equipment moves while anesthesia watches the patient: ventilator, monitoring one line at a time, infusions, pacing generator, chest drains to suction. Then comes a structured report with surgery, anesthesia, the ICU nurse and the intensivist present and no other tasks running. Standardized handoffs reduce omissions and technical errors in before-and-after studies; outcome data are thin.

• Patient: baseline EF, comorbidities, allergies, airway grade, home antithrombotics.
• Operation: grafts and targets, valve type and size or repair, approach, on or off pump, bypass and cross-clamp times, weaning difficulty.
• Final TEE: LV and RV function, valve gradients and leaks, SAM, effusion.
• Rhythm: underlying rhythm, AV conduction, wires and generator settings.
• Infusions and doses; fluids, blood products, factors and cell saver; protamine and last ACT; antifibrinolytic.
• Drains, urine output, last ABG, Hgb, K, ionized Ca, glucose and lactate.
• Plan: BP, CI and Hgb targets, extubation goal, antiplatelet timing, when to call the surgeon.

In the first hour, level and zero the transducers, compare the arterial line with a cuff pressure, and watch the PA trace for spontaneous wedging as the warming catheter softens and migrates. Measure CI and SvO₂; send ABG, CBC, coagulation tests with fibrinogen, K, Mg, ionized Ca, glucose and lactate; confirm pacing capture and sensing; and get a chest radiograph (tube, lines, mediastinal width, pneumothorax) and a 12-lead ECG.

Hemodynamics, low output and vasoplegia

• Preload: the stunned, stiff ventricle needs more filling than before surgery while capillary leak drains the vessels. Give 250 mL boluses and continue only while stroke volume or CI rises; pulse pressure variation needs passive ventilation and a regular rhythm. Crystalloid is the default (ALBICS 2022).
• Afterload: hypertension strains suture lines and raises bleeding; use nicardipine, clevidipine or nitroprusside, or nitroglycerin when ischemia or radial spasm is the worry. After mitral repair for regurgitation the LV loses its low-pressure outlet into the atrium and tolerates afterload poorly.
• Contractility: epinephrine, dobutamine or milrinone (a vasodilator that often needs norepinephrine alongside). Levosimendan did not improve outcomes as prophylaxis (LEVO-CTS 2017) or rescue (CHEETAH 2017).
• Rate and rhythm: stunning limits stroke volume, so output follows rate. AAI keeps the atrial kick (15% to 30% of stroke volume) when AV conduction is intact, DDD when it is not, and atrial pacing just above a junctional rhythm restores synchrony.

Low cardiac output syndrome is hypoperfusion despite adequate filling: CI under about 2.0 to 2.2 L/min/m² with rising lactate, falling SvO₂ and urine output and cool skin; definitions differ, so reported incidence does too. Exclude the fixable first: bleeding, tamponade, graft occlusion or spasm (new ST changes, VT), lost AV synchrony, low ionized calcium, acidosis, tension pneumothorax and dynamic LVOT obstruction, which inotropes worsen. Echo early, TEE if windows are poor. Escalate to IABP, Impella or VA-ECMO before lactate reaches 4 mmol/L (EACTS/ELSO/STS/AATS 2020); post-cardiotomy ECLS is used in 0.3% to 3.6% of operations, and survival to discharge was 34% in a large meta-analysis.

RV failure shows as CVP rising toward or above PAOP, a dilated RV with tricuspid regurgitation, low CI and worsening after fluid. Keep coronary perfusion with norepinephrine or vasopressin, add milrinone, dobutamine or epinephrine, lower PVR (oxygen, normocapnia, correct acidosis, inhaled nitric oxide or epoprostenol), keep PEEP modest and AV synchrony intact, stop fluid once CVP rises without a CI gain, and consider an RVAD or VA-ECMO.

Vasoplegia is low-SVR shock with a normal or high CI, reported in 5% to 45% depending on the definition (Unic-Stojanovic 2025; IBCC quotes about 5%). Drivers are excess nitric oxide and cGMP from inducible NO synthase, KATP channel opening and relative vasopressin deficiency. Risks: long bypass and cross-clamp, redo or complex surgery, preoperative ACE inhibitors, beta-blockers and loop diuretics, anemia, renal impairment and sepsis. Norepinephrine plus early vasopressin (VANCS 2017) is the base; methylene blue, hydroxocobalamin and angiotensin II are rescue options. Vasoplegia most often appears within the first 24 hours, and the absence of infection is a common diagnostic clue; septic shock has the same profile (MAP under 65, CI over 2.2, SVR under 800), so distributive shock that starts days later, or a positive culture, points to sepsis. After vasopressin is stopped, some patients develop reversible diabetes insipidus: watch urine output, sodium and fluid balance (Vasostrict label).

MI after surgery: some troponin release is universal, so the Fifth Universal Definition (2026) drops the old type 5 rule (over 10× URL within 48 h) for procedure-related MI within 30 days. It is likely when troponin has risen from baseline and is still rising at 6 h and 24 h (more than 35× URL at 24 h after surgery is an example the document calls arbitrary); expected surgical injury peaks at 3 to 12 h, so a peak 12 to 24 h after surgery may signal a complication. Immediately after surgery it is confirmed only by angiographic evidence such as graft failure plus a new wall-motion abnormality or lost viability in that territory.

Bleeding, tamponade and arrest

Re-exploration for bleeding is needed in about 2% to 11% of patients across series, most have a surgical source (72% in a 2021 Cureus series), and delay worsens outcomes, so EACTS 2024 leaves volume thresholds to judgment and favors early return to the OR. Meanwhile keep the patient warm, pH and ionized calcium normal and SBP low-normal; transfuse to TEG or ROTEM, fibrinogen and platelet results; and keep the tubes patent without stripping or breaking the sterile field (ERAS 2019: patency Class I, stripping Class III).

Tamponade after surgery is often a localized clot over the right atrium or behind the heart, so equalized pressures, Beck's triad and a large effusion may be missing, and positive-pressure ventilation blunts pulsus paradoxus. Suspect it with rising CVP and PA diastolic pressure, falling CI, SvO₂ and urine output, tachycardia, a narrowing pulse pressure, a pressure that responds only briefly to fluid, a widened mediastinum or drainage that stops abruptly; TEE beats TTE. Early tamponade (first 48 hours) comes from bleeding; delayed tamponade, usually after day 5, is linked to anticoagulation and can follow wire removal. Treatment is decompression: surgeon now, volume, keep the rate up, avoid vasodilators and high PEEP.

Arrest follows 0.7% to 8% of cardiac operations and about half of these patients survive to discharge, because the causes are reversible: VF in 25% to 50%, tamponade and bleeding in many of the rest (STS 2017). Shocks come first because success falls from 78% for the first to 35% and 14% for the second and third; compressions bridge to internal massage after resternotomy; routine epinephrine is withheld because return of circulation can bring severe hypertension and bleeding. STS names six roles: compressions, airway and breathing, defibrillation, team leader, drugs and infusions, and ICU coordinator, plus a resternotomy team that gowns at once. Resternotomy is standard through day 10; after that a senior clinician decides. Sternal infection or sepsis follows in about 5% of survivors.

Post-op atrial fibrillation

POAF follows 30% to 50% of cardiac operations (ESC 2024; ERAS/STS 2024 quotes 15% to 40%), more after valve and combined surgery, and most often starts on days 2 to 4. Triggers include pericardial blood and inflammation, atrial stretch, catecholamines, electrolyte shifts and beta-blocker withdrawal. It raises stroke risk, lengthens the stay and carries a 4- to 5-fold higher risk of recurrent AF over 5 years (ESC 2024).

• STS 2026: perioperative oral amiodarone Class I; beta-blockers and posterior left pericardiotomy IIa (PALACS 2021); eight IIb and three Class III (no benefit) recommendations cover the rest.
• Do not stop a home beta-blocker; ESC 2024 lists withdrawal as a POAF risk.
• Magnesium, steroids, sotalol, atrial pacing and botulinum toxin lack consistent evidence (ESC 2024).

Unstable POAF gets synchronized cardioversion (STS 2026 Class I). In stable patients, rate control (beta-blocker or diltiazem, amiodarone if pressure or EF is low) and rhythm control (amiodarone, then cardioversion) gave equal hospital days, and most patients were in sinus rhythm by 60 days (CTSN 2016). Replace K and Mg. Anticoagulation waits until bleeding risk settles: ESC 2024 says long-term OAC should be considered at elevated thromboembolic risk (IIa), STS 2026 calls timing and duration uncertain, and the PACES trial is testing it after CABG.

Lungs, glucose, kidneys and brain

Pulmonary complications follow up to 25% of cardiac operations (ERAS/STS 2024), and a bundle of 6 to 8 mL/kg predicted body weight, PEEP of at least 5 and driving pressure under 16 cm H₂O is linked to fewer of them. Aim to extubate within 6 hours (ERAS 2019 IIa) once the patient is awake and following commands, at least 36 °C, stable on modest support, not bleeding and oxygenating on minimal settings; unit protocols vary. Then screen swallowing before oral intake (vocal cord injury is frequent), coach incentive spirometry with a splinting pillow and walk early. Left lower lobe atelectasis and left effusion are common; a raised hemidiaphragm suggests phrenic nerve injury.

Glucose (STS 2009, Class I): an insulin infusion in the OR and for at least 24 hours in every patient with diabetes; under 180 mg/dL by infusion for persistent hyperglycemia during the ICU stay; 150 or less for patients in the ICU 3 days or more on a ventilator, inotropes, IABP, VAD, antiarrhythmics or dialysis; then a protocol switch to subcutaneous insulin. A 100 to 140 target did not reduce complications (GLUCO-CABG 2015).

AKI complicates 22% to 36% of cardiac operations (ERAS 2019), from hypoperfusion, nonpulsatile flow, hemolysis, emboli, inflammation and nephrotoxins such as recent contrast. ERAS 2019 (IIa) supports urinary TIMP-2 × IGFBP7 testing to find high-risk patients, then a KDIGO bundle: no nephrotoxins, ACE inhibitors and ARBs held 48 hours, close urine output and creatinine monitoring, no hyperglycemia or contrast, and hemodynamically guided volume (PrevAKI 2017).

Stroke is early (noticed on waking: aortic atheroemboli, air after open-chamber surgery) or delayed (after a normal awakening: POAF, low output). A 2019 JAHA meta-analysis found each in about 1% of patients, with operative mortality of 28.8% and 17.9% versus 2.4% without stroke. A new deficit is a stroke alert; major surgery within 14 days is a relative contraindication to thrombolysis, so thrombectomy is the usual option. Delirium affects 20% to 50% (ERAS/STS 2024): screen every shift with CAM-ICU or ICDSC (ERAS 2019 Class I), treat causes and use nonpharmacologic measures; prophylactic antipsychotics do not help. High-dose tranexamic acid causes seizures, so ERAS 2019 caps it at 100 mg/kg.

Watershed stroke: prolonged hypotension or a resuscitated arrest lowers flow most at the borders between arterial territories, so the infarcts are often bilateral; between the ACA and MCA they cause proximal weakness of both arms, the 'man in a barrel' pattern (Dogariu 2023). Report a new deficit at once and keep the MAP at target.

Air embolism. Arterial air, as after incomplete de-airing of an open chamber, is treated with 100% oxygen to shrink the bubbles, with the patient kept flat supine because head-down positioning may worsen cerebral edema, and hyperbaric oxygen is considered for neurologic deficits (McCarthy 2016). Coronary air favors the RCA, which arises from the anterior coronary sinus where bubbles are most likely to travel, giving inferior ST elevation, heart block and hypotension; raising perfusion pressure pushes the air through (Nezafati 2024). Venous air through an open central line: stop the entry, place the patient left side down in Trendelenburg (Durant), give 100% oxygen and aspirate air from the right heart through a central catheter (Gordy 2013).

Valves, TAVR, off-pump and minimally invasive surgery

After transfemoral TAVR the priorities shift away from bypass effects: groin bleeding (back or flank pain with a falling Hgb suggests retroperitoneal bleeding), distal pulses, early neuro checks, new LBBB or complete heart block (pacemakers in roughly 5% to 25%, more with self-expanding valves), rare coronary obstruction or annular rupture (sudden hypotension) and contrast AKI. Without another reason for anticoagulation, aspirin alone beat aspirin plus clopidogrel (POPular TAVI 2020: bleeding 15.1% vs 26.6%).

Off-pump CABG avoids the circuit, so there is less hemodilution, coagulopathy, transfusion and inflammation, but positioning the beating heart risks ischemia and incomplete grafting. ROOBY and CORONARY did not show it better (see Evidence), so it is used selectively, for example to avoid clamping a calcified aorta. Expect a warmer, less coagulopathic patient who needs early aspirin and a close watch for ischemia.

Minimally invasive valve surgery (ministernotomy, right minithoracotomy, robotic) often uses femoral cannulation, so check the groin and that leg's perfusion. Unilateral right pulmonary edema after minithoracotomy mitral surgery is reported in widely varying proportions (18% in one 393-patient series). Thoracotomy pain responds to regional blocks, and sternal precautions may not apply. ERAS/STS 2024 notes that long-term outcome data are still limited.

Sternal wound, mobility and ERAS Cardiac

Deep sternal wound infection is uncommon, under 1% to a few percent across series, but deadly: in-hospital mortality was about 14% versus 1.1% without infection in a 9,201-patient CABG series (Salehi Omran 2007). Risks: diabetes, obesity, bilateral internal mammary harvest, COPD, prolonged ventilation, re-exploration and transfusion. Prevention is a bundle (ERAS 2019 Class I; ERAS/STS 2024): nasal staphylococcal decolonization, chlorhexidine bathing and prep, clipping, weight-based cefazolin within 60 minutes of incision and redosed for long cases, prophylaxis no longer than 48 hours (STS 2006), glucose under 180 and normothermia. Watch for drainage, a sternal click or instability, fever or erythema, often after discharge, and check the radial and leg harvest sites too.

Early ambulation and upper-extremity exercise within comfort are safe and speed recovery (ERAS/STS 2024), the basis for Keep Your Move in the Tube. ERAS Cardiac 2019 also recommends goal-directed fluid therapy and tranexamic or aminocaproic acid (Class I), chemical VTE prophylaxis once hemostasis is secure, usually from day 1 (IIa), and opioid-sparing analgesia with acetaminophen, tramadol, dexmedetomidine and pregabalin or gabapentin (Class I); ERAS/STS 2024 adds chest wall blocks and notes new persistent opioid use in up to 10% to 15%. NSAIDs carry an FDA boxed warning against use for pain after CABG. Refer to cardiac rehabilitation before discharge.

Evidence and controversies

Society guidance used here: the STS 2017 resuscitation consensus (CSU-ALS), which updated the EACTS 2009 guideline; STS 2009 glucose; STS 2006–2007 antibiotic prophylaxis; STS 2026 POAF; EACTS/EACTAIC 2024 blood management; the 2020 post-cardiotomy ECLS consensus; and ERAS Cardiac 2019 with its 2024 ERAS/STS update. Unsettled: anticoagulation for POAF; how low a transfusion trigger is safe (TITRe2 2015 found more 90-day deaths with a 7.5 trigger, 4.2% vs 2.6%, as a secondary outcome); arrest details (RCUK 2025 pauses pacing to look for VF in every arrest, STS only in paced PEA); fixed chest tube triggers; and long-term results of off-pump and minimally invasive surgery.

Exam pearls

• Drainage that stops suddenly while filling pressures rise and CI falls: tamponade; call the surgeon.
• Heavy bleeding with normal coagulation tests: surgical source; re-explore early.
• Arrest: up to 3 shocks before compressions for VF, pacing for asystole, no routine epinephrine, resternotomy within 5 minutes.
• Low SVR with normal or high CI after bypass is vasoplegia: norepinephrine plus vasopressin, then methylene blue.
• Low CI despite filling: check rate, rhythm, AV synchrony and tamponade before inotropes; escalate to MCS before lactate reaches 4.
• SAM or LVOT obstruction: volume, beta-blocker, phenylephrine; stop inotropes.
• POAF peaks on days 2 to 4; unstable gets cardioversion; amiodarone is the Class I prophylaxis (STS 2026).
• Platelets that recover after bypass and fall again on days 5 to 10 suggest HIT.
• No NSAIDs for pain after CABG (FDA boxed warning).