Discussion:
Perioperative TEE is a critically important cardiovascular imaging modality. The esophageal position of its transducer provides superior cardiac imaging and allows continuous intensive monitoring of the heart before, during, and after cardiac procedures. TEE performed immediately prior to the surgical intervention allows the operative team to review the preoperative diagnostic findings, identify any new findings, and assist in the assessment of hemodynamics and myocardial function prior to onset of the operative procedure. TEE may facilitate catheter placement, real-time monitoring of volume status and myocardial function to inform selection of anesthetic agents, inotropic support, and management decisions. [5,6,7] Overall use of the TEE in pediatric population is quite safe with a reported incidence of complications rate in cardiac surgical patients is approximately 1-3%. [2,8] The Important complications are such as airway obstruction (1%), right main stem advancement of the endotracheal tube (0.2%), tracheal extubation (0.5%), and vascular compression (0.6%), esophageal perforation and even fatal gastrointestinal bleeding in 1.0%. [3,9]. Most problems in neonates and small infants are associated with respiratory compromise or vascular compression.[4] TEE probe insertion can also induce cardiovascular complications through vagal and sympathetic reflexes like; hypertension or hypotension, tachyarrhythmias or bradycardia and even myocardial infarction. Often arrhythmias are manifested as non-sustained ventricular and supra ventricular tachy arrhythmias, atrial fibrillation, and 3rd degree heart block and can even induce angina and myocardial ischemia. [10,11] Pediatric patients may be more vulnerable to TEE, in that the esophageal probe can significantly compress vascular structures, such as a normally positioned or aberrant right subclavian artery, Pulmonary artery,the descending aorta,the innominate artery,and the pulmonary venous confluence in an infant with total anomalous pulmonary venous return.[11,12]
To the best of our knowledge the recurrent VF induced by TEE probe has not been described in the literature till date. The authors have documented the intraoperative recurrent VF precipitated by TEE probe in a pediatric patient with OS-ASD, sub valvular and supravalvular PS and severe RV dysfunction. Eventually the reasons that were not understood, the patient developed repeated VF with TEE probe movements. The TEE probe is much closer to the heart since the esophagus and heart are right next to each other. It has been hypothesized that the small sized oesophagus of child with TEE probe in situ became a rigid rod like structure, and as it lies just next to heart [RV, PA] that might have an exaggerated compressive effect on LV that was already compressed due to the distended, low compliant RV, and precipitated VF.[Fig 2] This mechanism has also been confirmed by easy reversibility with biphasic DC shock [7 J] and excluding any residual ECG [ST/ T changes] and hemodynamics [systolic PB] effects prior or after development of VF, and reverting to the normal sinus rhythm following every episode of VF. Therefore, excluding the MI as a precipitating factor. It was also witnessed that mostly the VF episodes occurred during the forward insertion of the TEE probe from esophagus to trans-gastric or deep trans-gastric level and anteflexion. As the authors could not pin- point any other relevant cause for repeated VF, as a desperate attempt, the TEE probe was removed, following which the occurrence of repeated episodes of VF stopped immediately.
Conclusion : Paediatric TEE probe in young children may transform the oesophagus into a rigid rod like structure and may precipitate recurrent VF in paediatric patient with severe RV dysfunction causing leftward interventricular septal shifting and LV compression by further exaggerating the LV compressive effect.