Hemodynamic alterations during squint surgery may compromise the cardiac status of patients with valvular heart disease. It is a prudent measure to reduce the surgical response as it may further compromise the cardiac status. SubTenon block may serve to control the response to surgery by providing adequate analgesia and blunting of the oculocardiac reflex (OCR). We report a patient with pulmonary stenosis (PS) who was scheduled for squint surgery.

A 15-year-old child, weighing 42 kg, with PS was scheduled for squint surgery. At 6 years of age, balloon valvotomy was performed for symptomatic PS, with ECHO measuring the transvalvular gradient across the pulmonary valve as 90 mmHg. In the present study, the patient felt tired and cyanosed with more than normal activity (New York Heart Association class II). On examination, S2 was soft and an ejection systolic murmur in the pulmonary area and a pansystolic murmur in the tricuspid area were heard. The electrocardiogram (ECG) showed incomplete right bundle branch block. Chest X-ray revealed prominence of the right descending pulmonary vessels suggestive of pulmonary hypertension. ECHO revealed PS with a gradient of 54 mmHg, and pulmonary regurgitation with an early diastolic gradient of 24 mmHg and an end diastolic gradient of 10 mmHg. Moderate tricuspid regurgitation and pulmonary arterial hypertension were present. In the operating room, after attaching an ECG, blood pressure device, and pulse oximeter, anesthesia was induced with 30 μg fentanyl and 30 mg propofol. Muscle relaxation was achieved with 1.5 mg of vecuronium, and the airway was secured with a size 2 laryngeal mask airway (LMA). Sub-Tenon block was induced by 2 mL of 0.5% bupivacaine. There was no hemodynamic response to the surgical incision. The patient’s vital measurements remained stable throughout the procedure. After reversal of residual neuromuscular blockade, the LMA was removed. The child was comfortable and pain free. The child only once required paracetamol 500 mg for pain 6 hours after surgery.

Balloon valvuloplasty is the preferred therapy for isolated PS.¹ Most patients remain mildly to moderately cyanotic immediately after the procedure. Sometimes, patients with congenital isolated pulmonary valvular stenosis develop pulmonary incompetence following a single pulmonary valvoplasty² as was also noted in our patient.

An understanding of the underlying pathophysiological changes facilitates the anesthetic management of such patients. Management of anesthesia is designed to avoid increases in right ventricular oxygen requirements. Therefore, excessive increases in heart rate and myocardial contractility are undesirable, thus mandatory avoidance of laryngoscopic and surgical responses, and adequate analgesia in the perioperative period are essential. Cardiac output is very dependent on an elevated heart rate, but an excessive increase in heart rate can compromise ventricular filling. Thus, both bradycardia arising from the OCR, and tachycardia arising from surgical manipulation should be avoided. We used the LMA to avoid the laryngoscopic response. Also the sub-Tenon block used in this case dampened all the responses to surgical manipulation. Moreover, maintenance of eucapnia and avoidance of hypo xemia are mandatory in regulating controlled ventilation in such a patient.

Sub-Tenon bupivacaine 0.5% has been reported to reduce perioperative pain and undesirable side effects including hemodynamic alterations and the OCR in pediatric strabismus surgery performed under general anesthesia.³ In addition, peribulbar anesthesia has been shown to be an effective alternative to general anesthesia for strabismus surgery in an attempt to reduce morbidity and mortality in patients with high risk characteristics.⁴ We managed our case with sub-Tenon block which not only prevented a surgical response, but also prevented trigger of the OCR during squint surgery, as we observed no hemo dynamic change during the surgery.

We suggest that the use of sub-Tenon block along with an LMA for securing the airway is a very effective and safe anesthetic technique for squint surgery in a child with PS.