Anaesthesia Challenges for the Correction of Congenital Heart Diseases: A comprehensive Review

DR MANISH SONKUSALE

Sr. Consultant cardiac anesthesia,
KIMS-Kingsway, Nagpur

Abstract: Congenital heart diseases (CHDs) are complex structural abnormalities of the heart that often require surgical correction. Anesthesia management for CHD surgery poses unique challenges due to the underlying cardiac anatomy, physiological alterations, and associated comorbidities. This research review aims to provide an in-depth analysis of the anesthesia challenges encountered during the correction of CHDs. Through a comprehensive literature review, we discuss the preoperative assessment, intraoperative considerations, postoperative care, and emerging trends in anesthesia techniques. The review incorporates relevant references to support the discussion and provide a comprehensive overview of the topic.

Introduction:

Congenital heart diseases encompass a diverse range of cardiac abnormalities present at birth, affecting the heart’s chambers, valves, and blood vessels. Incidence of CHD is about 8–10/1000 live births worldwide and varies with modern diagnostics (1). Indian registry showed no community based data at birth as large number of birth goes unreported in 2005 Indian data showed CHD in India was around 2.5–5.2/1000 live births, and common lesions were ventricular septal defect (VSD), patent ductus arteriosus (PDA), transposition of great arteries (TGA) and pulmonary atresia(2). However another study by Bhardwaj et al showed prevalence in children (0-5 yrs.) as high as 19.4/1000 live birth and VSD (33%) being most common followed by atrial septal defect  (ASD) and tetralogy (TOF) . ASD is most common (2.4/1000) congenital heart lesion found in adult (3). Surgical intervention is frequently required for the correction of these defects which is often complicated by association with extra cardiac anomalies. Anesthesia plays a crucial role in ensuring adequate pain control, hemodynamic stability, and optimal surgical conditions. However, the complexity and variability of CHDs present unique challenges for anaesthesiologists. The frequency of anesthesia-related cardiac arrest in patients undergoing cardiac surgery is 0.79% in developed countries(4) which is almost 30% higher than patients without heart defect.  

Over last 2 decades with better understanding of pathophysiology and  more  involvement of anesthesiologist in perioperative care leads to improved outcome.

Anaesthesia for correction of congenital heart disease requires an understanding of (i) principles of neonatal and paediatric anaesthesia

1. Anaesthesia for correction of congenital heart disease requires an understanding of principles of neonatal and paediatric anaesthesia
2. Anatomy and physiology of congenital heart disease
3. Principles of cardiopulmonary bypass (CPB)
4. Expected postoperative complications of paediatric cardiac surgery.

Classification of congenital heart diseases

Congenital heart disease can be classified in a number of ways. A simple physiological classification (based on shunt type and outflow tract obstruction) is helpful for anaesthesia as shown in Table 1.

Table 1 A physiological classification of congenital heart disease

1. ‘Simple’ left-to-right shunt lesions—these cause an increased pulmonary blood flow (PBF)

• Atrial septal defect
• Ventricular septal defect (VSD)
• Atrioventricular septal defect (AVSD)
• Patent ductus arteriosus

The effect of the shunt on right ventricular (RV) and respiratory physiology differs depending on the level at which shunting occurs

2. ‘Simple’ right-to-left shunt lesions—these cause a reduction in PBF with cyanosis

• Tetralogy of Fallot.
• Pulmonary atresia
• Tricuspid atresia

3. Complex shunts—these cause mixing of PBF and SBF. Cyanosis occurs as a result of complex interactions between systemic SVR and PVR

• Transposition of the great arteries (TGA)
• Truncus arteriosus
• Total anomalous pulmonary venous drainage (TAPVD)
• Hypoplastic left heart syndrome

Most of these lesions (except TAPVD) are examples of a parallel circulation

4. Obstructive lesions

• Coarctation of the aorta
• Interrupted aortic arch
• Aortic stenosis
• Pulmonary stenosis

Preoperative Assessment

Preoperative Assessment: A thorough preoperative evaluation is crucial for developing an appropriate anesthesia plan for CHD surgery. This section discusses the importance of assessing cardiac anatomy and function, pulmonary hypertension, associated syndromes, genetic considerations, and the impact of age on anesthesia choices. Relevant studies and guidelines are referenced to support the discussion.

Routine history and examination should same for any neonate or pediatric patients but with particular attention to the following areas regarding cardiac ailment:

(i) Any history of recent upper respiratory tract infection, fever or wheeze as these predispose to adverse respiratory events. These babies should be checked for   presence of infection by raised C-reactive protein, liver transaminases, and/or white cell count may be indicative. If present then elective surgeries to be postponed as infections could be poorly tolerated after the immunomodulation associated with CPB.

(ii) Evidence of cardiac failure suggested by poor feeding, failure to gain weight, sweating, tachypnoea, tachycardia, and hepatomegaly. These children have poor cardiac reserve and may be very sensitive to the vasodilatory effects of induction agents.

(iii) Pulmonary hypertension (PHT) which is generally associated with CHDs because of increased pulmonary blood flow (left-to-right shunt) or obstructed pulmonary venous drainage. PHT develops earlier in some lesions (e.g. atrioventricular septal defects) and Down’s syndrome (Trisomy 21). From induction to separation from CPB every precaution to be taken to minimize pulmonary vascular resistance (PVR).

(iv) Cyanosis which increases the risk of hyperviscosity before operation and increased bleeding after operation, so these babies should not be dehydrated. Preoperative i.v. fluid therapy may be used to minimize the risk with a haemoglobin concentration of 18 g/dl or greater. They also have problems with of haemostasis and are at increased risk of postoperative bleeding. Therefore, consideration should be given to the use of antifibrinolytics and use of blood products

(v) Congenital syndromes are often associated with heart defects which have implications for perioperative care. Babies with congenital defect should be screened for CHDs as they may get unnoticed and add to mortality. There are many but common and important ones include: Di George syndrome which requires irradiated blood products and calcium supplementation.

Battery of investigations required as given below (6,7)

Blood investigations: complete blood counts, kidney liver function tests, coagulation profile , blood grouping, serology, C reactive protein, thyroid function test in selected group of patients.

Urine: routine and microscopy

Chest x-ray, ECG ECHO: severity of the disease to be assessed and discussed with pediatric cardiologist. We discuss echo with cardiologist to correlate with post correction finding.

Intraoperative Management

Anesthetic Techniques:

The selection of anesthetic techniques should be tailored to each patient’s specific cardiac defect and individualized needs. This section explores various options, including general anesthesia, regional anesthesia, and combined techniques.

General anesthesia is required for correction of congenital heart diseases whether it’s intracardiac or extra cardiac.

Starvation before surgery is as per standard ASA guidelines. We do allow clear fluid 2 hrs before surgery. Patients with cyanotic heart diseases may be started with 2 ml per kg of IV fluid to avoid dehydration.

Premedication: –  toddlers with separation anxiety should be premedicated with IV or oral agents. In our routine practise when IV line is already secured iv inj. Midazolam 0.1 mg per kg is drug of choice if required to be supplemented with inj. Ketamine 0.5-1 mg per kg. Use of other agents such as triclofos or clonidine is also reported.

The usual anaesthetic technique involves a gaseous or i.v. induction, muscle relaxation, opioid analgesia, and maintenance with a volatile agent.  Volatile induction with sevoflurane is frequently used in small infants where venous access may be difficult. Intravenous drug induction to be preferred if patient has sick heart.

Opioid based anesthesia still remains cornerstone for cardiac induction. Fentanyl in dose of 5-15 mcg/kg which has drastically decreased from earlier dose of 20-25 mcg/kg .  Fentanyl is hemodynamically stable, reduces stress response and well tolerated (8). Ketamine is also added in induction. It has no effect on SVR, increases mean arterial pressure (MAP), and is well tolerated in children with PHT.  Etomidate also provides haemodynamic stability but may be associated with adrenal suppression. Propofol profoundly decreases SVR and MAP, which alters shunt dynamics (9,10). In children with a right-to-left shunt, propofol should be avoided due to profound vasodilatation which leads to increase right to left shunt leading to worsening of cyanosis and hemodynamic instability (11). Induction times are prolonged in children with left to right shunt and cardiac failure so patience is required to prevent excessive drug administration.

Earlier Pancuronium was drug of choice due its tachycardic action However, recent years have seen a reduction in the amount of opioid used, in order to facilitate early extubation either immediately in theatre or within a few hours of admission to the intensive care unit (ICU).  This concept of “Fast-track anaesthesia” demands the use of nondepolarising neuromuscular blocking drugs with short duration of action, combining the ability to provide (if necessary) sufficiently profound neuromuscular blockade during surgery and immediate re-establishment of normal neuromuscular transmission at the end of surgery. Cisatracurium or Rocuronium is therefore recommended for neuromuscular blockade in modern cardiac surgery (12).

Sevoflurane is safe and maintains stable hemodynamic in the presence of CHD for induction and maintenance (13). Both sevoflurane and isoflurane do not alter shunt fraction. (14) Desflurane should not be used.

Uncuffed tracheal tube is conventionally used in infants and small children.  Cuffed tracheal tube may be used in cardiac surgeries as studies coming up with better safety with them (15, 16). A nasal rather than oral tracheal tube is common practice in some centres which makes ICU nursing care easier and are more stable. (6)

Monitoring:

Standard ASA monitoring like ECG, pulse oximetry and non-invasive blood pressure and end tidal CO₂ monitoring is used. Apart from that beat to beat Blood Pressure and Central pressure monitoring is required. For this arterial and central venous, appropriate to age will be secured and a urinary catheter inserted. [Table 2]  Arterial blood gas sample is analysed for acid base balance and proper ventilator parameters as these patients may have stiff lungs and acid base disorders.

Cerebral tissue oxygenation index, by using near-infrared spectroscopy is now considered mandatory by many experts. NIRS enables continuous monitoring of regional tissue oxygenation. Similar to pulse oximetry, cerebral oximetry uses the fact that oxygenated and deoxygenated haemoglobin absorb near‐infrared light to differing degrees (17).

Temperature monitoring: Rectal, esophageal or nasopharyngeal temperatures are monitored for all CPB cases as all cases have hypothermia during CPB

Transesophageal Echocardiography (TEE) : Multiplane 7.5 MHz probes are available for intraoperative use in neonates and infants. Intraoperative TEE provides the best immediate assessment of adequacy of the operative procedure and, if necessary, directs its revision in 15% of cases (18).

Age	Central line	Art line
Infants <5 kg	4 Fr/ 4.5  – 6 cm	24‐gauge for radial 2.5 Fr 2.5 cm for radial 22 g 6 cm for femoral
Infants/toddlers <10 kg	4.5 fr 6 cm 5.5 fr 8 cm	22‐ or 24‐gauge for radial 2.5 Fr 2.5 cm for radial 20-22 g  6 cm for femoral
Preschool children <20–25 kg	5.5 fr 8 cm	20‐ or 22‐gauge for radial 3 Fr 10cm for arterial
Older children	7 fr 13-16 cm	20‐ or 22‐gauge for radial

Surgical antibiotic prophylaxis is administered 30 min before skin incision according to hospital guidelines. First or second generation of cephalosporin is used for prophylaxis.

Additional drugs used in cardiac surgeries are Antifibrinolytics therapy and steroids. Antifibrinolytics (e.g. tranexamic acid or EACA epsilon amino –caproic acid) should be considered in all patients requiring CPB. Antifibrinolytics are effective at decreasing blood loss and blood product requirement in children undergoing cardiac surgery with CPB (20) Steroids (dexamethasone or methylprednisolone) may also be used to reduce the inflammatory response to CPB. (6)

Cardiopulmonary bypass in neonates and paediatrics (6,18)

Cardiothoracic surgeon, anaesthetist, and perfusionist works as team for success of surgery.

Oxygenator and circuit is primed with fluids which can be blood , blood product and/or colloid /crystalloid  .The priming volume of the CPB pump can be more than twice the child’s total blood volume leading to hemodilution with anaemia, thrombocytopenia, and a reduction in clotting factors, thereby contributing to the coagulopathy associated with CPB in children . Prime volume is constituted (addition of packed red cell) to keep haematocrit of 21–24% on CPB.

• Hematocrit on CPB is estimated by formulae:
• Hct on bypass= ( EBV X Hct) /EBV + circuit prime volume).
• EBV – Estimated blood volume
• Hct- hematocrit

Before the institution of CPB, heparin 300-400 units per kg is given to achieve an ACT of 400 s. Vigilance is required during surgical dissection and aortic and venous cannulation because there may be significant haemodynamic instability due to anatomical distortion or arrhythmias. Once CPB instituted, ventilation is stopped but anaesthesia, analgesia, and muscle relaxation must be maintained with additional dosage. Depending on the type of surgery, surgical technique, and/or surgical preference, the perfusionist will allow the child’s core temperature drift to 32⁰C.  For certain types of surgery involving the ascending aorta and aortic arch or low birth weight neonates with complex surgeries (arterial switch surgery for Transposition of great arteries with small VSD), it can be impossible to perfuse the body via the aortic cannula; therefore, the child is cooled to 15–178C and ice packs applied to the head. At this temperature, the circulation can then be completely stopped, allowing surgeons to manipulate heart and temporary removal of cannulas also. This is known as DHCA (deep hypothermic circulatory arrest) and during DHCA although cooled, brain can be selectively perfused by cannula in a carotid artery cannula or brachial artery (19).

α- Vs pH-stat

An α- or pH-stat strategy may be used at low temperatures where acid–base management becomes more complex. A pH-stat strategy needs addition of CO2 and more complex to manage, so now a days we follow α-stat strategy which is simpler and have better outcome. (6,18)

Monitoring on CPB

Perfusion pressure (MAP), venous saturations, cerebral oxygenation (NIRS), haematocrit, and electrolyte and acid–base status, coagulation parameters (ACT), urine output and temperature (nasopharyngeal/ rectal) are monitored.

Ultrafiltration on CPB

CUF is conventional ultrafiltration during CPB and MUF is modified ultrafiltration, usually done after separation from CPB. Ultrafiltration removes excess body water thereby increasing haematocrit, reduces extravascular lung water and also removes some inflammatory mediators. It has been shown to improve cardiac output and decrease PVR. MUF compared to CUF shows significant improvement of clinical conditions in the immediate post bypass period, but postoperative outcome parameters were not significantly influenced (21). We practise conventional ultrafiltration with good results. Differences between adult and Neonatal /pediatric CPB are mentioned in table 3.

	ADULT	PEDIATRIC
Estimated blood volume	65 ml /kg	<10 kg:85 ml /kg
Dilution effects on blood volume	25–33%	Up to 100–200%
Addition of whole blood or packed red blood cells to prime	Rarely Usually	common
Oxygen consumption	2–3 ml /kg/min	6–8 ml /kg/ min
Full CPB flow at 37 °C	50–75 ml/kg/min	150–200 ml/kg/min
Minimum CPB temperature	Rarely <30 °C	Commonly <30 °C
Use of total circulatory arrest or regional cerebral perfusion	rare	Common for some defects HLHS, Hypoplastic aortic arch
Perfusion pressure	50–80 mmHg	30–50 mmHg
Acid–base management	Primarily alpha‐stat	Primarily pH‐stat ≤30 °C
Measured PaCO2 differences	30–45 mmHg	20–80 mmHg

After surgical correction child can be weaned off from CPB following criteria are met, Deairing should be complete (can be confirmed with transoesophageal echocardiography)

• Both lungs seen to fully inflate and ventilation started.
• Acceptable Heart rate and rhythm (start epicardial pacing if required).
• Inotropes commenced (most infants require dobutamine / low-dose epinephrine after CPB and a lusitrope such as milrinone is also frequently used especially for complex surgery).
• Baby should adequately rewarmed – Core temperature > 36⁰C,
• Arterial blood gas should have normal acid–base and electrolyte status.
• Hematocrit in acceptable range.
• Blood available and blood products must be available and started as per protocol.

After separation from CPB, transoesophageal or epicardial echocardiography is performed to evaluate the adequacy of surgical repair, complete deairing, heart function and any new finding. If MUF is used, and complete, protamine 5 mg/kg or 1.5 times heparin is administered to reverse the heparinization. ACT(Activated clotting time ) is repeated to ensure adequate reversal . Blood and blood products are administered as required and may be guided by hospital protocols or thromboelastography.

After hemostasis, chest is closed and the child is transferred to the ICU. Invasive monitoring is continued during transfer and emergency drugs, fluid should be available. A comprehensive handover protocol is followed which includes, the surgical details, anesthesia details and echocardiography findings be given to ICU medical and nursing staff. With advancement in surgical skills and for better use of resources, babies can be extubated in operating room. Fast tracking in paediatric cardiac surgical patients is found to be safe with probable clinical benefit. (22). Fast tracking ICU stay and hospital stay for children with CHD and does not increase Sedation Agitation Score and incidence of adverse reactions.

SURGERY WITHOUT CPB

Some types of congenital heart surgery are performed without the use of CPB, for example, correction of coarctation of the aorta, pulmonary artery (PA) banding, and shunt procedures (modified Blalock–Taussig shunt or central shunt).

These procedures are palliative procedures and hemodynamic management is at most important here for balancing systemic and pulmonary flow. Pulmonary flow is altered with these procedures so do the saturations targets which may not change (PDA ligation), improve (shunt) or decrease (PA banding).

POSTOPERATIVE CARE (24)

Postoperative care of congenital heart surgeries is challenging due to immunomodulation on CPB, labile hemodynamic and ailment of pulmonary arterial hypertension. In western scenario most postoperative care is undertaken by a specialist paediatric intensivist but in INDIA paediatric cardiac anaesthetist are primarily involved in postoperative care of these babies in association with pediatric intensivist. Pediatric cardiac anesthesiologist thus must be familiar with common postoperative complications to anticipate and take immediate attention. Protocolled approach, Anticipating problems and early treatment are cornerstone of successful management of child in postoperative period.

Standard transfer sheet to include following points and to be handed over to intensivist and staff as shown in table 4.

Table 4. standard handover sheet

Surgical aspects
-intraoperative findings? Compared to before?
-surgical technique was performed? Any problems?
-drainages were placed intraoperatively (e.g., pleural drainage, mediastinal drainage)?
-assessment of postoperative result?
-intraoperative transoesophageal echocardiography performed and what were the findings (residual gradient, valve insufficiency, residual shunt, myocardial function)?
– Did any intraoperative arrhythmias occur? How were they treated?
-any intraoperative bleeding problems occur? How were they treated?

Anesthesiology aspects
– Tube size and brand, cuffed and uncuffed?
– Ventilation settings (FiO2, tidal volume, rate, peak pressure and PEEP)
– Central venous catheter: location of insertion, size
– Arterial access: location, size
– Was an LA or pulmonary artery catheter placed?
– Anaesthetics and cardiac medication used (catecholamine’s, vasodilators, anti-arrhythmic) and their dosages
– Heparinization and current coagulation levels,ACT Level
– Use of blood products (pack red cells, platelet concentrates, fresh frozen plasma)

Cardiopulmonary Bypass
– Bypass time
– Aortic cross clamp time
– Cardiac arrest time
– Minimum temperature during bypass
– Was hemofiltration performed at the end of the bypass

Some major postoperative care aspects are discussed below:

Hemodynamic

Maintaining cardiac output is prime important in postoperative period. All invasive monitoring to be continued in postoperative period. Measuring cardiac output in babies is difficult so MAP, venous saturation and lactate levels can be used as surrogate measures. Heart rate and stroke volume, both determines cardiac output and to be maintained near age specific range (50 percentile)

Stroke volume depends on preload, afterload and contractility. Here echocardiography can give cause for low cardiac output. Poor left or right sided dysfunction should be treated by inotropes like dobutamine, Milrinone and epinephrine can be added. If patient is vasodilated in postoperative period then noradrenaline is good choice. Preload is assessed by central or left atrial pressure, IVC collapsibility and should be treated with fluids.

Fluid and electrolyte management

As capillary leak is a normal reaction to bypass and the subsequent inflammatory process induces edema of all organs, the amount of free water intake should be limited postoperatively. Therefore, fluid intake is ideally reduced to 30–50% of the normal maintenance on the first postoperative day and then increased day by day to 75 and finally 100% on the following days.

Dextrose with low sodium content is usually fluid of choice. Albumin                 1 gm/kg/day may be required to maintain oncotic pressure and intravascular volume.  

Ventilation in ICU

The majority of patients are ventilated after cardiac surgery Pulmonary function is affected by a large variety of preoperative (congested lungs , pulmonary hypertension) and intraoperative(duration of CPB, wet lung ,lung compliance) and postoperative factors like atelectasis , collapse, wet lung, pneumothorax.

PRVC is preferred mode for ventilation with targeted tidal volume of 8-10 ml per kg and age appropriate respiratory rate. Ventilation should be titrated after blood gas report.

Some important variation

Univentricular heart: In univentricular hearts, the balance between systemic and pulmonary circulation is very important to avoid pulmonary overcirculation at the cost of inadequate systemic perfusion. At an oxygen saturation of around 75–85%, a nice balance between systemic and pulmonary perfusion is achieved (Qp/Qs = 1:1).

Fontan circulation:

The transpulmonary blood flow is depending completely on the intrathoracic pressure and pulmonary vascular resistance , so ventilation with low PEEP and early extubation should be strategy.

Pulmonary hypertension: should be mildly hyper ventilated with higher po2 to have low pco2 and high po2.

Sedation

In most centres, a combination of an opiate (morphine, fentanyl) and a benzodiazepine (midazolam) is administered intravenously continuously in the initial postoperative period. Propofol or dexmedetomidine can also use for sedation. 

Analgesia

To reduce postoperative pain, a fixed and standardized combination of non-steroidal analgesics (i.e., paracetamol, ibuprofen) and opiates (fentanyl) is usually used for analgesia for the first 2–3 days.

Kidney function:

Urine excretion of at least 2 ml/kg/h after cardiac surgery is required to ensure adequate fluid balance. Due to CPB and associated SIRS, fluid homeostasis is greatly altered in neonates and small babies. They retain water which kidneys are unable to handle. Suitable diuretics in the postoperative phase are primarily loop diuretics (Furosemide/Torsemide). They are administered as continuous infusion. If excretion is insufficient or the fluid balance is clearly positive, peritoneal dialysis should be initiated early.

Temperature Control

Temperature management is critical in CHD surgery due to its impact on myocardial function and systemic vascular resistance. Hypothermia also affect coagulation parameters so rewarming and thereafter temperature to be maintained in ICU.

Coagulation and Haemostasis

Patients with cyanotic CHDs often present with deficient coagulation factor and platelet aggregation abnormalities, necessitating meticulous attention to haemostasis. Priming with crystalloid leading to lower hematocrit and dilution of coagulation factors, addition of starches on CPB, platelet trauma and dysfunction alters coagulation.

Complications after cardiac surgery

can be divided into five general areas:

(i) Arrhythmias

(ii) Bleeding

(iii) Systemic inflammatory response syndrome (SIRS)

(iv) Pulmonary hypertension

(v) Low cardiac output syndrome (LCOS)

i) Arrhythmias

Tachycardia in ICU may be due to simple reasons like agitation of the child or fever or electrolyte disturbances, these should be ruled out.  Cardiac related reason like poor left or right ventricular function or rhythm issues may cause tachyarrhythmia. Amiodarone is drug of choice to treat tachyarrhythmia. Junctional ectopic tachycardia (JET) is dreaded arrhythmia found in patients with intracardiac repair and treatment is cooling baby to 34⁰c and reducing/stopping inotropes (23). Orally only available drug Ivabradine, acts on sinus node and found to be effective in treatment. Bradycardia should be treated by temporary pacing or isoprenaline.

ii) Bleeding after cardiac surgery

Bleeding after cardiac surgery is common and reduced by a meticulous

surgical technique and the use of antifibrinolytics such as tranexamic acid. Blood loss into surgical drains is measured every hourly till drain removal. Losses of 5 ml /kg/ hr in the first 2 h or over 2 ml /kg /hr thereafter warrants attention. Treatment involves correcting hypothermia and clotting factor abnormalities (including checking the ACT for adequate heparinization reversal with protamine). Calcium levels can be checked and supplemented. Tranexamic acid infusion can be started after bolus. Drop in hematocrit with loss of 10ml per kg demands immediate surgical review ad may be reexploration.

iii) SIRS 

SIRS manifested 8-12 hr after surgery and leads to stiff lungs, reduced cardiac function and fever immediately after surgery. MUF and addition of steroids reduces SIRS incidence.

iv) Pulmonary arterial hypertension.

PAH Can be flow related (seen in patient with left to right shunt) or obstructive lesion (aortic stenosis, total anomalous pulmonary venous connection). This can be reduced or prevented from increasing by ventilator strategies as mentioned above and addition of pulmonary vasodilators.

PAH increases right ventricle afterload and reduces rt ventricle outflow which subsequently leads to reduction in left ventricular preload and output.

Sudden increase in PAH leading to hemodynamic compromise is known as PAH crises. Treatment of PAH crises involves administration of some or all of the following: high inspired concentrations of oxygen with hyperventilation leading to alkalinisation (aim for pH.7.45), nitric oxide, Milrinone, sildenafil, prostacyclin, and magnesium.

v) LCOS – low cardiac output syndrome

LCOS is transient decrease in systemic perfusion leading to mismatch in oxygen delivery and consumption. It is manifested as metabolic acidosis, increase lactates, oliguria, cold peripheries, tachycardia, hypotension and low mixed venous oxygen saturation.  Management involves searching and treating cause such as addition of inotropes to increase stroke volume and addition of vasopressors for vasodilation, preload increase with fluids and correction of acidosis with bicarbonate.

Complications in Postoperative period Some specific complication associated with specific common pathologies are listed below and to be watched for:

Cardiac defect/operation	Specific early postoperative problems and complications
VSD closure	complete AV block,  residual shunt
AV canal correction	Pulmonary hypertensive crisis, complete AV block, JET, AV valve stenosis or incompetence
Anomalous pulmonary venous connection (correction)	Pulmonary hypertensive crisis, atrial arrhythmia,
Tetralogy of fallot (TOF) correction	Right ventricular diastolic dysfunction , JET, complete AV block, residual pulmonary stenosis, residual VSD, pulmonary insufficiency after a trans annular patch
Aortic stenosis correction	Residual stenosis, disruption of left ventricular diastolic function, aortic insufficiency, AV block
Sub aortic stenosis (resection)	Residual stenosis, mitral valve injury, (ventricular) arrhythmia, AV block
Coarctation of the aorta (resection)	Residual obstruction, post-coarctectomy syndrome, injury to the recurrent laryngeal nerve, chylothorax
Mitral stenosis correction	Pulmonary hypertensive crisis, residual stenosis, mitral regurgitation, left ventricular dysfunction
Superior cavopulmonary anastomosis (Glenn, Hemifontan)	Cyanosis, hypertension, edema/congestion of the upper half of the body, Chylothorax
Fontan completion	Ascites, pleural effusions, edema, cyanosis, low cardiac output, arrhythmias
TGA (switch operation)	Coronary ischemia, left ventricular dysfunction, neo aortic insufficiency, peripheral pulmonary stenosis
Abnormal left coronary artery from pulmonary artery	Myocardial dysfunction, mitral regurgitation

Emerging Trends and Advancements:

With improved skills and availability of pediatric cardiologist who are also trained in antenatal echocardiography, more neonates are coming for surgery. Anesthesiologist now are facing challenges of giving anesthesia and postoperative care to these babies but at the same time highlighting their role as a complete perioperative physician. 

Surgeons are now aiming for small incisions and minimally invasive approach so we as an anesthesiologist should be brace for more challenges like single lung ventilation and cardiac surgery in small children. However advent of biofabrication of viable and growing implants will hopefully reduce biological aggression and morbidity while ensuring sustainable excellent outcomes.

As surgeons are posing more challenges we have advanced with ERAS (early recovery after surgery) in pediatric cardiac surgery with rising numbers and success rate of on table extubation. NIRS has shown brighter future for brain protection in neonate and small children.

Conclusion:

Congenital cardiac surgery remains one of the most demanding and technically complex areas in cardiothoracic surgery. The correction of congenital heart diseases requires meticulous anesthesia management to ensure optimal patient outcomes. Congenital cardiac surgery at the crossroads of disciplines requires team approach and interdisciplinary communication. Advanced knowledge of the underlying pathophysiology, establishment of individualized care-plans, improved technology and techniques, multidisciplinary effort has contributed to significantly improved survival and quality-of-life expectations. This research review has provided a comprehensive overview of the anesthesia challenges encountered during CHD surgery, including preoperative assessment, intraoperative considerations, postoperative care, and emerging trends.

References:

1. Hoffman JI, Kaplan S. The incidence of congenital heart disease. J Am Coll Cardiol 2002; 39:1890‑900.
2. Saxena A. Congenital heart disease in India: A status report. Indian J Pediatr 2005; 72:595‑8.
3. Bhardwaj R, Rai SK, Yadav AK, Lakhotia S, Agrawal D,Kumar A, et al. Epidemiology of congenital heart disease in India. Congenit Heart Dis 2015;10:437‑46
4. Odegard KC, DiNardo JA et al, The frequency of anesthesia-related cardiac arrests in patients with congenital heart disease undergoing cardiac surgery Anesthesia and Analgesia, 01 Aug 2007, 105(2):335-343
5. Ramamoorthy C, Haberkern CM, Bhananker SM, Domino KB, Posner KL, Campos JS, et al. Anesthesia‑related cardiac arrest in children with heart disease: Data from the pediatric perioperative cardiac arrest (POCA) registry. Anesth Analg 2010; 110:1376‑82.
6. James M Peyton , Michelle C White Anaesthesia for correction of congenital heart disease Continuing Education in Anaesthesia, Critical Care & Pain | Volume 12 Number 1 2012
7. Sandip Waman Junghare, Vinayak Desurkar Congenital heart diseases and anaesthesia Indian J Anaesth 2017; 61:744-52.
8. Duncan HP, Cloote A, Weir PM et al. reducing stress response in the pre-bypass phase of open heart surgery in infants and young children: a comparison of different fentanyl doses. Br J Anaesth 2000; 84: 556–64
9. Oklu E, Bulutcu FS, Yalcin Y et al. Which anesthetic agent alters the hemodynamic status during pediatric catheterization? Comparison of propofol versus ketamine. J Cardiothorac Vasc Anesth 2003; 17: 686–90
10. Williams GD, Jones TK, Hanson KA et al. The hemodynamic effects of propofol in children with congenital heart disease. Anesth Analg 1999; 89: 1411–6
11. White MC. Approach to managing children with heart disease for noncardiac surgery. Paediatr Anaesth 2010. doi:10.1111/j.1460-9592. 2010.03416
12. Thomas M Hemmerling 1, Gianluca Russo, David Bracco Neuromuscular blockade in cardiac surgery: an update for clinicians , Ann Card Anaesth . 2008 Jul-Dec; 11(2):80-90. doi: 10.4103/0971-9784.41575
13. Suruchi Hasija, Sandeep Chauhan Comparison of speed of inhalational induction in children with and without congenital heart disease, Ann Card Anaesth. 2016 Jul-Sep; 19(3): 468–474
14. Laird TH, Stayer SA, Rivenes SM et al. Pulmonary-to-systemic blood flow ratio effects of sevoflurane, isoflurane, halothane, and fentanyl/midazolam with 100% oxygen in children with congenital heart disease. Anesth Analg 2002; 95: 1200–6
15. Liang Chen, Jun Zhang, Guoshi Pan et al Cuffed Versus Uncuffed Endotracheal Tubes in Pediatrics: A Meta-analysis Open Med (Wars). 2018; 13: 366–373.
16. Jennifer C DeMichele , Nikhil Vajaria et al Cuffed endotracheal tubes in neonates and infants undergoing cardiac surgery are not associated with airway complications J Clin Anesth. 2016 Sep; 33:422-7.
17. Katherine L Zaleski , Barry D Kussman Near-Infrared Spectroscopy in Pediatric Congenital Heart Disease J Cardiothorac Vasc Anesth. 2020 Feb; 34(2):489-500. doi: 10.1053/j.jvca.2019.08.048.
18. Vivian G Nasr, James Dinardo, the pediatric cardiac anesthesia handbook 1st edition
19. Frederick A. Hensley, Jr. A Practical approach to cardiac anesthesia 5th edition.
20. Katherine Schertz , Oliver Karam , Michelle Demetres et al Prophylactic Use of Antifibrinolytics During Pediatric Cardiac Surgery With Cardiopulmonary Bypass on Postoperative Bleeding and Transfusion: A Systematic Review and Meta-Analysis Pediatr Crit Care Med . 2022 Nov 1;23(11):e517-e529
21. Norifumi Kuratani MD, PhD , Piyaporn Bunsangjaroen MD b et al Modified versus conventional ultrafiltration in pediatric cardiac surgery: A meta-analysis of randomized controlled trials comparing clinical outcome parameters The Journal of Thoracic and Cardiovascular Surgery Volume 142, Issue 4, October 2011, Pages 861-867
22. Rajnish Kumar Garg, Jameel Khan Thareen, et al Fast tracking after repair of congenital heart defects, Indian Journal of Thoracic and Cardiovascular Surgery volume 37, pages183–189 (2021)
23. Navaneetha Sasikumar,1 Raman Krishna Kumar,2 and Seshadri Balaji3 Diagnosis and management of junctional ectopic tachycardia in children. Ann Pediatr Cardiol. 2021 Jul-Sep; 14(3): 372–381.
24. Melissa B. Jones, Dr Klugman, MD , pediatric cardiac intensive care handbook