Anesthetic Management of a Neonate with Coarctation of the Aorta and Duct-Dependent Circulation Posted for Tracheoesophageal Fistula Repair

Abstract

Coarctation of the aorta (CoA) is a congenital heart disease found in a newborn with an incidence of 6%. It presents a significant clinical challenge in neonates posted for major surgeries like tracheoesophageal fistula (TEF) repair. We report the case of anesthetic management of a 2-day-old infant with CoA and duct-dependent circulation posted for TEF repair. We describe how physiology affects its perioperative management and the role of maintaining balance in peripheral vascular resistance and systemic vascular resistance to maintain ductal flow.

INTRODUCTION

Congenital anomalies of the heart and cardiovascular system occur in 7–10/1000 live births.[1] Coarctation of the aorta (CoA) accounts for 6% of all congenital heart diseases (CHDs).[2] It can be associated with other cardiac anomalies such as bicuspid aortic valve, ventricular septal defect (VSD), patent ductus arteriosus (PDA), and transposition of the great arteries and extracardiac anomalies such as esophageal atresia, tracheoesophageal fistula (TEF), coloboma, heart defects, atresia choanae, growth retardation, genital abnormality, and ear abnormality, renal and musculoskeletal anomalies, and DiGeorge syndrome.

CASE REPORT

A 2-day-old male neonate, the first baby of twin gestation, presented with esophageal atresia and suspected TEF. The baby was born preterm at 35 weeks of gestation (late preterm) through vaginal delivery. The baby cried immediately after birth and had no respiratory distress. The baby had a birth weight of 1.7 kg (fourth percentile Olsen preterm growth chart) small for gestational age and low birth weight. Screening echocardiography (ECHO) for cardiac anomalies showed CoA and hypoplastic aortic arch. PDA was 1.5 mm in diameter, and it was supporting the distal circulation. A bicuspid aortic valve was present. To maintain the patency of the ductus arteriosus, an injection alprostadil was started at 0.05 μg.kg⁻¹.min⁻¹ initially and a maintenance dose of 0.01 μg.kg⁻¹.min⁻¹. In the neonatal intensive care unit (NICU), the patient was started on injection calcium gluconate 2.5 ml in 50 ml 10% dextrose maintenance fluids 80 mL.kg⁻¹.day⁻¹ at 5 mL.h⁻¹. Nasal continuous positive airway pressure (CPAP) 8 cm of H₂O with 30% FiO₂ to avoid apnea was initiated with continuous oral aspiration. The baby had preductal SpO₂ – 94% and postductal SpO₂ – 90%; right arm blood pressure (BP) was 70/40 mmHg and right leg BP was 60/40 mmHg. Cardiovascular system examination showed normal first and second heart sounds. Respiratory rate was 35/min, and chest was clear on auscultation with bilateral equal air entry. No other dysmorphic features were present. Ultrasound (USG) of the cranium and spine was normal. USG abdomen showed mildly dilated renal pelvicalyceal systems. Investigations on day 1 age were as follows: hemoglobin (Hb) – 11.7 g%, platelets – 2.68 L.mm⁻³, total leukocyte count – 9000/mm³, prothrombin time – 14.8 s, activated partial thromboplastin time – 40 s, international normalized ratio – 1.15, pH – 7.385, HCO₃ – 21.2 mEq.L⁻¹, pCO₂ – 36 mmHg, pO₂ – 46 mmHg, urea – 26.6 mg.dl⁻¹, creatinine – 0.93 mg.dl⁻¹, Na⁺ – 136 mEq.L⁻¹, K⁺ – 4.09 mEq.L⁻¹, and Ca⁺ – 8.6 mg.dl⁻¹. The patient was given packed red blood cell – 15 mL.kg⁻¹ infusion day before surgery as per the neonatologist. On the day of surgery, arterial blood gas values were as follows: pH – 7.28, HCO₃ – 21, pCO₂ – 43, pO₂ – 102, and serum Ca⁺ – 8.9 mg.dl⁻¹. In view of the present condition, the plan of surgery was bronchoscopy and proceed. The patient had a 24 g intravenous (i.v.) cannula in the left hand and an umbilical vein catheter. Injection alprostadil infusion at 0.01 μg.kg⁻¹.min⁻¹ was continued, and the neonate was transported in preheated cover with oxygen by face mask and SpO₂ monitoring to the operating room. Inside the operating room, the three-lead electrocardiogram (ECG) was placed in the posterior aspect of the shoulder and left flank. Pulse oximetry probes were connected in the right thenar aspect of the hand and right foot. Two neonatal-size BP cuffs were connected one in the right arm and one in the left leg. Warming blanket was placed over the legs and abdomen, and axillary skin temperature was monitored. The patient was preoxygenated with 100% O₂ for 60 s and slowly induced with sevoflurane 3.5% and injection fentanyl 2 μg.kg⁻¹ i.v. and spontaneous mask ventilation. Check bronchoscopy was done to look for a tracheal opening of TEF which was not identified. The plan of surgery now was esophagostomy and feeding jejunostomy. The patient was paralyzed with injection atracurium 0.5 mg.kg⁻¹ and intubated with 3.0 mm Microcuff endotracheal tube. Ventilation was confirmed with bilateral equal air entry and absence of stomach distension. Injection alprostadil 0.01 μg.kg⁻¹.min⁻¹ was continued and ringer's lactate with 1% dextrose was started at 4 mL.h⁻¹. Maintenance was with O₂⁺ air with FiO₂ 0.4 and sevoflurane 1%–2% and pressure control ventilation (PCV) mode, Pinsp – 15 cmH₂O, positive end-expiratory pressure – 3 cmH₂O, frequency – 36/min, and inspiration: expiration – 1:2. Tidal volume achieved was 10–15 ml, and end-tidal carbon dioxide was maintained between 35 and 40. Intraoperatively, injection dopamine 5 μg.kg⁻¹.min⁻¹ was started to maintain the BP head across the coarctation segment. To maintain the patency of PDA, paracetamol was avoided and hyperoxia and hypocarbia were avoided. The aim was to maintain systemic vascular resistance (SVR), not intending to increase or decrease it, to maintain forward ductal flow in the aorta [Table 1]. BP was maintained at upper limb 79/49 mmHg and lower limb 69/47 mmHg. A single episode of hypotension was present intraoperatively and responded to fluid bolus. HR was maintained between 140 and 160/min. SpO₂ was maintained at upper limb 92% and lower limb 90%.

Table 1.

Problem-wise management of duct-dependent obstructive cardiac heart disease in this case

Risk factors	Anesthetic concerns	Approach to management
Preterm	Apnea of prematurity, retinopathy of prematurity, hypoglycemia, hypocalcemia, hypothermia	Although this was late preterm 35 weeks+2 days postconceptional age and less prone for these complications than early preterm. Avoiding high FiO2, glycemic management, and temperature management was taken care of
Coarctation of the aorta, hypoplastic aortic arch (left systemic blood flow obstructive lesion)	Poor perfusion of postductal organs such as liver, kidneys, intestines, and lower body	Pulse oximetry and blood pressure cuff in both upper (preductal) and lower limbs (postductal) Maintaining pressure head with inotropic support Monitoring of poor perfusion and lactic acidemia Maintain PDA open
Duct-dependent circulation	PDA to be kept patent for perfusion in organs supplied by postductal aorta	PGE1 injection alprostadil infusion Avoiding hyperoxia Avoiding increased SVR will lead to a reversal of flow in PDA from left to right Avoiding hypocarbia and hyperoxia, leading to pulmonary vasodilation and coronary steal and reduced systemic perfusion
	Maintaining the balance between pulmonary and SVR	Any decrease in SVR will lead to reduced pulmonary blood flow and hypoxia So inhalational anesthetic concentration should be balanced and adjusted Any decrease in PVR like increasing FiO2 will reduce the systemic flow from PDA to the aorta and lead to hypoperfusion so these are avoided
IPPV	Increase in PVR	May lead to hypoxia due to reduced pulmonary blood flow and blood flowing through PDA to the systemic circulation Hence, minimal FiO2 is required to maintain acceptable saturation for preventing NEC, metabolic acidosis, and kidney/hepatic injury should be used
Esophagostomy	Airway securing issues Recurrent laryngeal nerve injury	Air entry confirmed after positioning and endotracheal tube secured with bimalleolar tape Identification of recurrent laryngeal nerve by the surgeon
Fluid management in the neonate	More prone to postoperative hyponatremia and fluid overload Judicious calculation of fluid of surgical field loss	Optimize fluid administration and avoiding over judicious administration

FiO₂=Fraction of inspired oxygen, PDA=Patent ductus arteriosus, PGE1=Prostaglandin E1, SVR=Systemic vascular resistance, PVR=Pulmonary vascular resistance, NEC=Necrotizing enterocolitis, IPPV=Intermittent positive pressure ventilation

The neonate tolerated the surgery, and post surgery patient was put on elective ventilation in PCV mode FiO₂ 0.3 with injection alprostadil 0.01 μg.kg⁻¹.min⁻¹ and injection dopamine 5 μg.kg⁻¹.min⁻¹. The neonate was extubated after 4 h and put on nasal CPAP in view of prostaglandin E1 (PGE1) infusion. Injection dopamine was tapered and stopped. Day 3 of age, patient was doing well with a pH- 7.365, HCO3- 21.0 mEq.L⁻¹, pCO2 – 31 mmhg, pO2- 45.2 mmhg, pO2- 45.2mmhg. The patient was on alprostadil infusion, passing adequate urine, off dopamine, and with minimal BP gradient.

DISCUSSION

CoA is due to an abnormal focal thickness and narrowing of the aorta in the region of the ductus arteriosus.[3] It is associated with other congenital heart anomalies such as a bicuspid aortic valve (60%), distal arch hypoplasia (14.2%), VSD (12.8%), and PDA (7%).[4] CoA causes left ventricular pressure overload and a reduction in lower body perfusion. Its physiologic consequences will depend on the severity of coarctation, the extent of antegrade flow from the ductus arteriosus, and the severity of associated heart lesions.

It causes distal hypoperfusion due to narrowed segment. Distal aortic perfusion is by blood from the pulmonary artery through the ductus arteriosus (duct-dependent systemic circulation). This causes differential cyanosis and differential BP with higher oxygen saturation in preductal limbs and lower oxygen saturation in postductal limbs and BP gradient in the upper and lower limbs. Closure of the ductus arteriosus after birth initially occurs at the aortic orifice. Its anatomical closure is delayed for several weeks or months. Closure of the aortic end of the ductus arteriosus may abruptly impede blood around the aortic shelf and increase the severity of the lesion.[5] Neonates with critical CoA characteristically present with metabolic acidosis, weak pulses, poor peripheral perfusion, and tachypnea with respiratory distress for up to 7 days, when results of ductus arteriosus closure come into effect. This can mimic sepsis.[6] Neonates with critical CoA are unlikely to survive infancy without intervention. Neonates with critical CoA are likely to have right ventricular hypertrophy on the ECG, with cardiomegaly and increased pulmonary vascular markings on the radiograph. Antenatally fetal ECHO can detect CoA, though with difficulty, by unusual right ventricular dilation compared to left. Transthoracic ECHO will detect the severity of the lesion and associated cardiac anomalies. Computed tomography and magnetic resonance imaging give an excellent image resolution to detect the anatomy and severity of the lesion.

The perioperative management starts with recognition of lesion and is focused on maintaining ductal patency with alprostadil (PGE1) infusion along with general stabilization with inotropes, fluids, and mechanical ventilation. Alprostadil is started at 0.05–0.1 μg.kg⁻¹.min⁻¹ and increased every 20 min up to 1 μg.kg⁻¹.min⁻¹. The desired response is palpable pulses, resolving acidosis, target saturation of 75%–85%, and lactates <2 mmol.L⁻¹. Later, it is reduced to 0.025–0.050 μg.kg⁻¹.min⁻¹ if rapid improvement is there. Common side effects of alprostadil are apnea, fever, hypotension, flushing of the skin, diarrhea, convulsions, tachycardia, or bradycardia. Uncommon are hypothermia, cardiac arrest, disseminated intravascular coagulation, and vascular fragility. All complications are less with a dose of <0.05 μg.kg⁻¹.min⁻¹. Infective endocarditis prophylaxis is recommended for these patients as it is found by Rushani et al. that children with cyanotic CHD lesions or left side lesions or endocardial cushion defects have a relatively high risk of infective endocarditis.[7]

Anesthetic management – The neonate's perfusion and metabolic derangement were corrected 12–24 h before surgery. Hb should be preoptimized in neonates due to the high concentration of fetal hemoglobin.

Monitors – Standard monitors with both preductal and postductal BP, noninvasive BP, and pulse oximetry saturations should be measured. BP cuff is put in the right upper limb and another in the lower limb. This will detect any residual gradient in real time [Figure 1].

Figure 1.

Representation of flow across ductus arteriosus. (a) ductus arteriosus open and coarctation open, (b) ductus arteriosus open and coarctation restrictive, (c) ductus arteriosus closed and coarctation restrictive

Anesthetic goals, induction, and maintenance [Table 2] – Two i.v. lines are sufficient and a central venous catheter may not be required. Neonates on PGE1 infusion should be continued to keep the ductus arteriosus patent. i.v. or inhalational induction can be carried out depending on the availability of i.v. access and the child's physiological condition and cooperation. Various factors that can increase SVR and reduce pulmonary vascular resistance (PVR) are to be avoided[8] [Table 3]. Sevoflurane is the agent of choice for inhalational induction, and propofol is used for i.v. induction. Likely, physiological consequences of varying SVR and PVR on shunt and cardiac output must be considered. Tracheal intubation is facilitated by neuromuscular blocking agents like injection atracurium 0.5 mg.kg⁻¹ i.v. All factors which can lead to the closure of the ductus arteriosus are to be avoided [Table 4].

Table 2.

Anesthesia goals in a patient with coarctation of the aorta with duct-dependent circulation

a. To keep the ductus arteriosus patent, to maintain the heart rate, contractility, and preload to maintain cardiac output

b. Keep forward flow through it into the aorta

c. Prevent reversal of flow from the aorta to pulmonary artery

d. To maintain the blood pressure so that forward flow through the stenosed segment is maintained and to minimize the gradient by keeping ductus arteriosus open

e. If there is an associated atrial septal defect or VSD, reduction in the PVR: SVR ratio should be avoided. Such reductions will increase pulmonary blood flow and will necessitate an increase in cardiac output to maintain systemic blood flow

d. Avoid increase in SVR as increase in SVR will worsen forward flow

SVR=Systemic vascular resistance, PVR=Pulmonary vascular resistance, VSD=Ventricular septal defect

Table 3.

Factors deciding the direction of blood flow through the shunt

Increase pulmonary blood flow		Increase systemic blood flow
Decrease PVR Hypocapnia Pulmonary vasodilators (nitrous oxide, volatile anesthetics, vasopressin, phosphodiesterase inhibitors) Metabolic alkalosis	Extracardiac or aorta pulmonary shunt Atrial level shunt Ventricular shunt	Increase PVR Hypoxia Hypercarbia Hypothermia High hematocrit Invasive positive pressure ventilation Metabolic acidosis Alpha-adrenergic stimulation
Increase SVR Sympathetic stimulation Vasoconstrictors Hypothermia		Decrease SVR Vasodilators - nitrites, PDE inhibitors Spinal and epidural anesthesia Deep general anesthesia Hyperthermia Low hematocrit Beta-agonists

SVR=Systemic vascular resistance, PVR=Pulmonary vascular resistance, PDE=Phosphodiesterase

Table 4.

Factors which cause closure of ductus arteriosus

Hyperoxia[8]

Low levels of circulating prostaglandins - NAIDS, COX inhibitors, paracetamol

Rise in intracellular calcium

Inhibition of potassium channels

Response to acetylcholine

Response to norepinephrine

Release of angiotensin 2

Reduced PVR

PVR=Pulmonary vascular resistance

Stable hemodynamics as close to preprocedural values as possible in addition to maintaining normothermia and normocapnia is desired. Oxygen and air are used for maintenance avoiding hyperoxia as it reduces PVR increasing left to right shunt. Intraoperatively, small doses of fentanyl 1–2 μg.kg⁻¹ may obtund hemodynamic response [Table 5]. An i.v. antiemetic (dexamethasone 0.2–0.5 mg.kg⁻¹ or ondansetron 0.1 mg.kg⁻¹) is usually given to avoid nausea and vomiting. Isotonic maintenance fluids will be required in the vast majority of cases with attention to blood sugar monitoring. It is important to account for volume in flushes and drug dilutions. The majority of patients are extubated at the end of the procedure and recovered in a routine fashion, with special attention to lower-limb perfusion. Postoperative care should be given in ICU setup with good pain relief with opioids and control of nausea and vomiting.

Table 5.

Anesthetic drug effects and doses

Anesthetic drug	SVR	PVR	Dose
Potent volatile agents	↓	↓	0.5-1 MAC
Nitrous oxide	-	↑
Opioids
Fentanyl	↓	-	1-2 µg.kg−1, 0.5-2 µg.kg−1.h−1
Morphine	↓	-	0.05-0.2 mg.kg−1, 0.02-0.2 mg.kg−1.h−1
Midazolam	-	-	0.5 mg.kg−1 PO, 0.1 mg.kg−1 IV, 0.02-0.3 mg.kg−1.h−1
Ketamine with glycopyrrolate	↑	No effect (if CO2 is normal)	3-4 mg.kg−1 PO, 1-2 mg.kg−1 IV, 5-20 µg.kg−1.min−1
Propofol	↓	-	2-3 mg.kg−1, 100-300 µg.kg−1.min−1
Dexmedetomidine	↑-↓	↓	1 µg.kg−1 (over 10 min), 0.2-1 µg.kg−1.h−1

SVR=Systemic vascular resistance, PVR=Pulmonary vascular resistance. ↑-↓=Increase or decrease any way (bidirectional)

CONCLUSION

Anesthetizing patients with CoA is challenging and requires knowing of the pathophysiology to maintain perfusion perioperatively. It requires a multidisciplinary approach involving anesthesiologists, neonatologists, and pediatric surgeons.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the legal guardian has given his consent for images and other clinical information to be reported in the journal. The guardian understands that names and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.