Resuscitation after cardiac surgery and the role of surgery in congenital heart disease

Overview

Cardiac arrest after heart surgery is uncommon but different from a ward arrest: the cause is usually mechanical or electrical and often reversible quickly (VF, tamponade, bleeding). The patient has pacing wires, monitoring lines and a sternotomy that can be reopened at the bedside.

Congenital heart disease is the commonest congenital abnormality (about 8 per 1000 live births). Surgery can be palliative (to buy time) or corrective, and timing is planned to prevent heart failure and irreversible pulmonary hypertension.

Part 1: Resuscitation after cardiac surgery

Causes and differences from standard ALS

• Incidence after cardiac surgery about 0.7–2.9%.
• Most arrests are from ventricular fibrillation, tamponade or major bleeding.
• European cardiothoracic (EACTS) guidance adapts standard advanced life support because the causes are specific and the chest can be reopened.

Shockable rhythm (VF or pulseless VT)

1. Call for help; start the arrest protocol.
2. Defibrillate at once. A precordial thump is acceptable only within 10 seconds of onset and must not delay shocks.
3. Give up to three successive shocks before starting external compressions.
4. If three shocks fail → emergency resternotomy, with internal defibrillation and internal massage.

Non-shockable rhythm

• Asystole or extreme bradycardia: connect the epicardial pacing wires and pace; give atropine.
• PEA: think of tamponade, tension pneumothorax and severe hypovolaemia/bleeding; check drains and the chest.
• If pacing and drugs fail, or CPR becomes prolonged, reopen the sternum early: internal massage is more effective than external compressions in these patients.

Emergency resternotomy

• Needed in about 0.8–2.7% of cardiac surgical patients.
• Done in the ICU by a team, with full sterile technique (gown, gloves, whole-bed drape).

Steps:

1. Cut through the skin sutures down to the sternal wires with a scalpel.
2. Cut all the wires; the sternal edges spring apart, which may itself relieve tamponade.
3. Suction blood and clot.
4. Insert the retractor and open the sternum.
5. If output returns, call senior help. If not, identify the grafts, then do internal massage and internal defibrillation.

Internal cardiac massage

• Two-hand technique is safest: right hand flat behind the heart (round the apex), left hand flat on the front; squeeze at about 100 per minute with flat palms and straight fingers.
• Risks: avulsion of a bypass graft (the LIMA is most at risk) and right ventricular rupture.
• After mitral valve surgery, do not lift the apex – this can rupture the back of the left ventricle.

Postoperative tamponade

• Blood collects around the heart early after surgery (often with blocked drains).
• Signs: low blood pressure, high CVP/JVP, pulsus paradoxus, falling urine output; Kussmaul's sign (JVP rises on inspiration).
• Treatment after cardiac surgery is re-exploration (resternotomy), not just needle aspiration.

Low cardiac output state

Myocardial function often dips for a few hours after bypass (ischaemia-reperfusion injury).

Signs: cold peripheries, low urine output, metabolic acidosis, low blood pressure.

Causes and fixes:

Mechanical support

Arrhythmias after surgery

• Atrial fibrillation in about 30% after CABG. Keep potassium above 4.5 mmol/L; beta-blocker, amiodarone, digoxin, or cardioversion.
• Bradycardia or heart block: temporary pacing through the epicardial wires.

Part 2: The role of surgery in congenital heart disease

Fetal circulation and changes at birth

Three shunts in the fetus: ductus venosus, foramen ovale and ductus arteriosus.

• With breathing, pulmonary resistance falls; rising oxygen makes the ductus arteriosus constrict within hours.
• Clamping the cord lowers right atrial pressure, so the foramen ovale closes.
• Functional closure is quick; structural closure takes months. A probe-patent foramen ovale persists in about 20% of adults without significance.

Causes and associations

Most cases are multifactorial. Severe lesions can be seen on fetal echo in the second trimester.

Classification

Central cyanosis appears when deoxygenated haemoglobin exceeds about 3–5 g/dL in arterial blood.

What surgery aims to do

• Close a shunt (PDA, ASD, VSD).
• Relieve obstruction (coarctation, pulmonary stenosis in Fallot).
• Reroute blood (arterial switch for TGA, TAPVD repair).
• Palliate in small or unstable babies: keep the duct open with prostaglandin, balloon atrial septostomy to improve mixing, or a systemic-to-pulmonary shunt (e.g. Blalock–Taussig type) to increase lung flow before full repair.
• Operate before irreversible pulmonary vascular disease develops.

Acyanotic lesions

#### Patent ductus arteriosus (PDA)

• Commoner in premature babies.
• Continuous "machinery" murmur in the left 2nd intercostal space.
• Indomethacin (a COX inhibitor) can close it in the first weeks. Prostaglandin E keeps a duct open.
• Spontaneous closure after 6 months is rare. Close most by preschool age, even without symptoms (risk of endocarditis, heart failure, Eisenmenger).
• Methods: percutaneous coil or umbrella device, or ligation/division through a left thoracotomy (large duct or very small baby).

#### Coarctation of the aorta

• About 6–7% of congenital heart disease; usually just distal to the left subclavian artery, near the ductus. Mostly boys; in a girl think of Turner syndrome.
• Infantile (preductal): baby is well until the duct closes, then heart failure and poor lower-body perfusion. Give prostaglandin to reopen the duct, resuscitate, then repair.
• Adult type: upper limb hypertension, radio-femoral delay, weak leg pulses, claudication, murmur over the back; collaterals cause rib notching and the "3 sign" on chest X-ray.
• Treatment: surgical repair through a left thoracotomy; stenting is standard for adults with isolated coarctation.
• Untreated, most die before 40 (heart failure, endocarditis, aortic rupture, cerebral haemorrhage). Hypertension may persist after repair.

#### Atrial septal defect (ASD)

• Close in the first decade even if asymptomatic, to prevent right heart failure, endocarditis and paradoxical embolism.
• Methods: device closure in the catheter lab, or open repair on bypass by direct suture or patch. Primum defects may need mitral repair too.

#### Ventricular septal defect (VSD)

• Commonest congenital lesion overall (about 20–30%).
• Perimembranous type is commonest (70–80%); others are muscular, inlet (AV canal) and subarterial.
• Loud pansystolic murmur at the left sternal edge. Small defects (maladie de Roger) cause few problems; 30–50% close by 5 years.
• Large defects cause heart failure in the first months; pulmonary vascular changes begin from about 1 year.
• Indications for closure: large defect, failure of medical treatment, shunt (Qp:Qs) over 2:1, rising pulmonary resistance, or complications (aortic regurgitation, infundibular stenosis, endocarditis).

#### Eisenmenger syndrome

A long-standing left-to-right shunt causes pulmonary hypertension until right-sided pressure exceeds left and the shunt reverses (cyanosis, clubbing).

Cyanotic lesions

#### Tetralogy of Fallot

• Commonest cyanotic lesion in children surviving to 1 year (about 4–6% of all congenital heart disease).
• Four features: VSD, overriding aorta, pulmonary (infundibular) stenosis, right ventricular hypertrophy.
• Cyanosis usually appears in the first year as the stenosis worsens; hypercyanotic spells; children squat, which raises systemic resistance and pushes more blood to the lungs.
• Chest X-ray: boot-shaped heart with oligaemic lung fields. Diagnosis by echo.
• Complete repair at about 4–6 months: patch the VSD and resect the infundibular obstruction. A palliative shunt may be used first in a baby too small or sick for repair.
• Late survival after repair is good (about 95% at 5–10 years).

#### Transposition of the great arteries (TGA)

• Aorta from the right ventricle, pulmonary artery from the left: two parallel circuits. Life depends on mixing (PFO, ASD, VSD, PDA).
• Commonest cyanotic lesion presenting in the newborn: severe cyanosis in the first 48 hours.
• X-ray: "egg on its side" heart with a narrow pedicle and plethoric lungs.
• Emergency care: prostaglandin to keep the duct open and balloon atrial septostomy.
• Definitive: arterial switch operation in the first weeks of life. Some later need surgery for neopulmonary stenosis.

#### Total anomalous pulmonary venous drainage (TAPVD)

• About 1–2%. All pulmonary veins drain to the systemic venous side instead of the left atrium.
• Surgery reconnects the pulmonary venous confluence to the left atrium; urgent if the veins are obstructed.

Quick revision

• Arrest after cardiac surgery: VF, tamponade, bleeding.
• VF: three quick shocks; if they fail, resternotomy within the ICU.
• Asystole/bradycardia: epicardial pacing; PEA: tamponade, tension pneumothorax, hypovolaemia.
• Internal massage: two hands, about 100/min; watch the LIMA; don't lift the apex after mitral surgery.
• IABP: inflate in diastole, deflate in systole.
• PDA: indomethacin closes; prostaglandin opens; machinery murmur.
• Coarctation: radio-femoral delay, rib notching, "3 sign"; repair via left thoracotomy.
• Fallot: VSD, overriding aorta, RVOT obstruction, RVH; repair at 4–6 months.
• TGA: newborn cyanosis; prostaglandin, septostomy, arterial switch.

Written by The House Job from standard references (Bailey & Love).

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