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.