The utility of transesophageal echocardiography during and after Fontan operations in small children

Experience with intraoperative ultrasound in paediatric cardiac surgery

OBJECTIVE

Intraoperative ultrasound was introduced to evaluate the adequacy of repair after surgical repair of congenital cardiac malformations. Our purpose was to review the evolution of this technique at our centre.

METHODS

We evaluated all intraoperative ultrasound studies undertaken between 1997 and 2002, reviewing the data from 1997 through 2001 retrospectively, but undertaking a prospective audit of studies undertaken from 2002 onwards. In all, we carried out a total number of 639 intraoperative ultrasound studies, from a possible 2737 cardiac operations (23.3%), using the epicardial approach in 580 (90.7%), and transoesophageal ultrasound in the other 59 patients (9.3%). Median age was 0.6 years, with an interquartile range from 0.06 to 3.6 years.

RESULTS

The findings obtained using intraoperative ultrasound influenced the surgical management in 63 of the 639 patients (9.9%), suggesting the need for additional surgery in 26, adjustment of the band placed round the pulmonary trunk in 16, preoperative assessment of the cardiac malformation in 5, and confirming the need for prolonged support with cardiopulmonary bypass for impaired ventricular function in 16. There were 18 early reoperations, 5 of which may have been predicted by intraoperative ultrasound. Of the 183 studies reviewed prospectively in 2002, it was not possible to obtain the complete range of views in 8 (4.4%), while in 27 patients (14.7%), the postoperative findings using transthoracic interrogation differed from the findings obtained immediately following bypass.

CONCLUSION

Intraoperative ultrasound is an important technique for monitoring the results of complex congenital cardiac surgery. The immediate recognition of significant lesions, together with multidisciplinary discussion, allows for improved management and prevention of early surgical reintervention.

Anaesthetic technique for transoesophageal echocardiography in children

OBJECTIVE

To document the safety and efficacy of an anaesthetic technique in paediatric patients undergoing transoesophageal echocardiography (TOE).

METHODS

Prospective descriptive study performed in a children's hospital with all patients undergoing TOE. Topical analgesia of the pharynx was achieved with lidocaine. Anaesthesia was induced with midazolam (25 microg.kg-1), fentanyl (1 microg.kg-1), and propofol (0.5-1 mg.kg-1), followed by a continuous infusion of propofol (5-10 mg.kg-1.h-1).

RESULTS

Thirty patients are reported. The mean age was 11.4 +/- 5.1 years (range 1-22) and weight 40.5 +/- 22.1 kg (range 10-110). All the patients tolerated the procedure well. Two patients experienced brief oxygen desaturations during induction, 10 patients coughed during the procedure, and six patients had significant muscle activity requiring supplemental doses of propofol. None of the patients experienced nausea or vomiting.

CONCLUSION

We conclude that our anaesthetic technique in spontaneously breathing paediatric patients during TOE is effective and appears to be safe in children with heart disease.

Intraoperative evaluation of pulmonary artery flow during the Fontan procedure by transesophageal Doppler echocardiography

After the Fontan procedure, pulmonary artery (PA) flow is maintained without right ventricular pump function. We evaluated intraoperative PA flow velocity patterns using transesophageal Doppler echocardiography (TEE) immediately after cardiopulmonary bypass (CPB) in patients during Fontan or hemi-Fontan procedures. We studied 10 patients with single-ventricle physiology (age range, 5 mo to 3 yr 1 mo). Anesthesia was induced and maintained with fentanyl. After induction of anesthesia, a pediatric TEE probe was inserted into the esophagus. All patients had surgical repair involving direct anastomosis of the right atrium to the PA. Immediately after completion of CPB, adequacy of the atriopulmonary anastomosis was assessed and PA flow velocity was recorded. In all patients, the atriopulmonary anastomosis was clearly defined using a single-plane TEE probe, and PA flow recording was completed successfully. Intraoperative PA flow velocities showed two distinct patterns. Biphasic forward flows with peak velocities during systole and diastole were observed in six patients. The remaining four patients showed forward flows with flow reversals. The four patients demonstrating flow reversals showed significantly reduced fractional shortening (26.5+/-2.1% vs. 35.5+/-6.3%) and larger pressure gradient between the right atrium and left atrium (10.8+/-1.3 mm Hg vs 8.0+/-0.9 mm Hg) when compared to those without reverse flow. Two patients with reverse flow required reoperation because of hypotension. Because PA flow is influenced by pulmonary vascular resistance and left ventricular function, TEE assessed intraoperative PA flow should be further evaluated as a useful predictor of surgical outcome after a Fontan procedure.

Transesophageal echocardiography (TEE) in congenital heart disease with focus on the adult

Remarkable innovations in medical and surgical approaches over the past several decades now allow for correction of major cardiac defects in children, even in early infancy. These advances have provided for survival of many pediatric patients with congenital heart disease into adulthood. Although transthoracic echocardiography remains the primary imaging technique for the characterization of simple and complex congenital cardiovascular malformations in the pediatric and adult age groups, high-resolution transesophageal imaging has markedly expanded the anatomic and hemodynamic assessment in these patients. The benefits of this imaging approach apply particularly to those with challenging or limited transthoracic examinations or poorly characterized congenital cardiovascular malformations. The utility of TEE in defining the anatomy of the usual spectrum of congenital cardiac malformations is well established. The transesophageal approach has been shown to provide additional diagnostic information over conventional transthoracic imaging for specific structural cardiac anomalies and in the perioperative setting, the opportunity for confirmation of preoperative diagnoses, and modification of the surgical plan if new or different pathology is identified. This imaging modality also may reliably provide for immediate detection of suboptimal surgical repairs and significant postoperative residua, potentially improving the efficacy of the surgical intervention. This accounts for the vital role of this technology in perioperative management and integration into the standard of care in many congenital heart centers. The usefulness of TEE also has been documented during diagnostic and therapeutic cardiac catheterizations of patients with structural cardiac anomalies, allowing for safer and more effective application of these technologies. The experience supports the use of TEE as a useful approach in the surveillance of the adult with operated and unoperated congenital heart disease.

Intraoperative transesophageal echocardiography in congenital heart disease

This article reviews the use of intraoperative echocardiography during repair of congenital heart defects. Although initial experience was generated using epicardial transducers, there has been a trend in recent years toward the use of transesophageal echocardiography (TEE) in the operating room. This has encouraged increased involvement from cardiologists and anesthesiologists. New probe designs have provided biplane imaging via the TEE approach in infants weighing more than 2.5 kg. Smaller infants may still require epicardial imaging, so it is helpful for surgeons to maintain some skill in this technique. This article reviews the utility of intraoperative echocardiography for various congenital heart defects by providing examples from our experience at Duke University Medical Center since 1987 with close to 2,000 cases. Furthermore, we review and report for the first time our experience with TEE since 1993 in the operating room during infant heart surgery (493 patients). Along with this experience, we provide a review of important series in the literature to outline recommendations for the use of echocardiography during infant heart repair.

Use of miniature biplane transesophageal echocardiography during pediatric atrial catheter interventional procedures

We reported the use of a new miniature biplane TEE probe during pediatric cardiac interventional catheterization procedures. Use of this imaging modality provided significant advantages during dilation of obstructed venous pathways and closure of interatrial defects. Procedural characteristics and specific congenital heart lesion-related advantages were discussed.

Reproducibility of quantitative pediatric transesophageal echocardiography

Transesophageal echocardiography (TEE) is commonly used to monitor cardiac function and to assess cavitary size. For the interpretation of quantitative echocardiographic data, the degree of their reproducibility should be considered. The variability of quantitative TEE was evaluated in this study. To assess intraobserver, beat-to-beat, interobserver, and repositioning variability, TEE examinations of 46 patients with congenital heart defects were analyzed. The mean beat-to-beat variability of 8.5% (range 4.2% to 12.3%) exceeded the mean intraobserver variability of 4.9% (1.9% to 8.1%). The mean interobserver difference between two observers was 3.4% (0.2% to 11.9%). Differences in image acquisition caused by repositioning of the transesophageal probe contributed the most (6.4% to 13.3%; mean 10.5%) to the variability of two-dimensional TEE. Changes seen on TEE studies should be interpreted as abnormal only when they exceed the total variability of this method.

Transoesophageal echocardiography in congenital heart disease

The development of paediatric transoesophageal ultrasound imaging represents an important advance in the diagnosis and management of the patient with congenital heart disease. Although primary diagnostic transoesophageal studies are seldom indicated in infants and unoperated children, they have an important role in the older child, especially where there has been prior cardiac surgery. Diagnostic studies are most appropriate for abnormalities of venous return, the atria, atrioventricular valves and the left ventricular outflow tract. Two other important areas in which transoesophageal imaging is playing an increasing role in the management of the paediatric patient is in monitoring of surgical repair.

Pediatric biplane transesophageal echocardiography: preliminary experience

Recent development of prototype pediatric biplane transducers has extended the use of biplane TEE imaging to the neonate. One such TEE probe with 64 imaging elements in each pallet was used perioperatively in 46 infants and children (weight 2.9 to 32 kg) undergoing surgery for complex congenital heart disease. The success rate for passing the transducer, complications of the procedure, and the number of cases in which the vertical plane provided information that was not available from the horizontal plane were determined. Probe insertion was successful in all patients. Imaging was discontinued in one neonate because of possible airway compression by the probe. Image quality was excellent in the other 45 patients. The vertical plane added information over that obtained from the horizontal plane in 58 (44%) of the 132 anomalies identified. The addition of the vertical plane was especially useful in imaging abnormalities of the ventricular outflow tracts.

Thromboembolism after the Fontan procedure and its modifications

The frequency of thromboembolism after the Fontan procedure has not been specifically addressed. Seventy patients underwent this operation between 1987 and 1992, and complete information was available on 64. Forty-five had a right atrium-pulmonary artery anastomosis, 17 had a total cavopulmonary connection, and 2 had a right atrium-right ventricle anastomosis. No patient received anticoagulants for more than 8 months postoperatively. Seven patients died in the early postoperative period (< 30 days). Ten cases of thromboembolism were identified in the follow-up, which ranged from 6 to 55 months (mean follow-up, 24.5 +/- 17 months). They occurred 7 days to 4.5 years after the Fontan repair. Seven thombi were on the systemic venous or pulmonary aspect of the circulation and three, on the systemic arterial aspect. Freedom from thromboembolism was 75% at 4 years. We conclude that thromboembolism is common after the Fontan procedure; it can occur several days to years postoperatively; it is an important cause of morbidity; and it may partly explain late death after the Fontan operation. Our data suggest that all patients undergoing this procedure require long-term anticoagulant therapy.

Monitoring during paediatric cardiac anaesthesia

Monitoring of paediatric anaesthesia has become increasingly more complex in recent years and this is particularly true of cardiac anaesthesia. The purpose of this review is to give a comprehensive update of published material related to both routine and specialized cardiac monitoring. Routine monitoring can be particularly affected by the alterations of cardiac rhythm, blood flow, cardiac output and oxygenation which result from the congenital heart abnormalities themselves, the type of surgery undertaken and the effects of cardiopulmonary bypass. The use of specialized monitoring is becoming more widespread, particularly in the areas of cerebral function, mixed venous oxygenation, cardiac output measurement and coagulation. In the last five years, with the development of smaller probes, a great deal has been published on transoesophageal echocardiography. The use of the current monitors of cerebral function still remains controversial despite the need for a monitor of adequate brain perfusion, reflecting the need for a great deal of further research in this area. This review will concentrate on particular areas which have seen the most profound changes and on monitoring that may form the standards of tomorrow. Finally, amongst all the technology, it should not be forgotten that the most important clinical monitor is the bedside clinical monitoring of the physicians themselves.

Routine use of transesophageal echocardiography and color flow imaging in the evaluation and treatment of children with congenital heart disease

We reviewed our experience with transesophageal echocardiography (TEE) and color flow imaging in 157 consecutive patients with known or suspected heart disease to ascertain the impact of this technology on patient care. TEE was performed for diagnostic purposes (22/157), during interventional cardiac catheterizations (13/157), and during operative procedures (122/157). Diagnostic studies were performed after transthoracic echocardiography (TTE) in 21 of 22 patients. TEE was performed because TTE was inconclusive (15/21) or failed to provide sufficient detail of an abnormality (6/21). TEE detected an abnormality in 6 of 15 inconclusive TTEs. TEE was helpful during interventional cardiac catheterizations, particularly during umbrella closure of septal defects and in patients with complex venous and atrial anatomy undergoing transseptal puncture. TEE studies performed before cardiac operations significantly changed the diagnosis in only 5 of 122 (4%) patients, but the information changed the surgical approach in 4 of 5 of these patients. Postoperative TEE assessment more frequently changed care and resulted in further surgical management in 9 of 122 (7%) or a change in medical management in 6 of 122 (5%) patients. TEE was discontinued because of complications before studies were completed in only 4 of 157 (3%) patients. TEE and color flow imaging is a useful adjunct to care of children with known or suspected congenital heart disease.

Intraoperative echocardiography by a new miniaturized epicardial probe: preliminary findings

Miniaturized probes constitute recent progress in the field of epicardial echocardiography. We recently used a new miniaturized probe, derived from a standard transesophageal probe, in a series of 12 adult patients who underwent cardiac surgery in order to test the possibility of obtaining new views for epicardial imaging. This study demonstrates the feasibility and safety of performing intraoperative echocardiography when using a miniaturized epicardial probe. This probe may be placed on a broader epicardial and vascular area, thus overcoming the size limitations of the commonly used epicardial probes. The major limitation found with the miniaturized probe, however, was the inability to obtain a true four-chamber view from the ventricular apex, due to the difficulty of holding the probe motionless between the apex and the diaphragm while the heart is beating. Although extensive experience with larger groups of patients and different pathologies will be required to define the full potential of this new probe, the advent of the miniaturized probe may further expand the applicability of epicardial echocardiography in pediatric patients during surgery for congenital heart disease.

Outpatient transesophageal echocardiography with intravenous propofol anesthesia in children and adolescents

Outpatient transesophageal echocardiography (TEE) was performed in 10 children and adolescents (aged 3 to 19.5 years, mean 13.5 years; weight 12 to 91 kg, mean 49 kg), including two with Down's syndrome and one with autism, for diagnostic evaluation of issues unresolved by transthoracic echo examination (TTE). Issues for TEE: evaluation for atrial septal defect (two patients); anatomy of left ventricular outflow tract obstruction (one patient); aortic valve anatomy before valvuloplasty for insufficiency (one patient); evaluation for cause of cyanosis after Fontan operation (one patient); determination of source of high-velocity intracardiac turbulence after atrioventricular septal defect repair (one patient); rule out cardiac embolic source in patient with stroke (one patient); evaluate prosthetic valve function and rule out thrombus (one patient); determination of anatomic relationship of mitral valve to a ventricular septal defect before surgery for complex cyanotic heart disease (one patient); and evaluation for aortic dissection in Marfan's syndrome (one patient). Intravenous propofol anesthesia administered without endotracheal intubation by an anesthesiologist allowed successful outpatient TEE in nine patients; midazolam-conscious sedation was used in one. Outpatient TEE resolved diagnostic issues in all patients without complication, thereby avoiding cardiac catheterization in six patients and supplementing catheterization for preoperative planning in four patients. TEE can be performed safely and effectively with propofol anesthesia in the outpatient setting in carefully selected children and adolescents to provide vital diagnostic information. However, given the invasive nature of the procedure and the use of anesthesia, outpatient pediatric TEE should be used judiciously.

Transoesophageal echocardiography in neonates, infants and children: applicability and diagnostic value in everyday practice of a cardiothoracic unit

OBJECTIVE

To determine the applicability of and information obtained by transoesophageal echocardiography in neonates, infants, and children in every day practice of a cardiothoracic unit.

DESIGN

Four month prospective study.

SETTING

Supraregional centre for paediatric cardiothoracic services.

PATIENTS AND METHODS

58 patients aged between four days and 16 years with a wide range of cardiovascular disease underwent transoesophageal echocardiography under sedation or general anaesthetic. One of two paediatric probes (6 or 7 mm diameter), or an adult probe (13 mm in diameter) was used. Whenever possible the investigation was immediately preceded by precordial echocardiography.

MAIN OUTCOME MEASURES

Success, failure, technical difficulties, and complications of probe introduction and, when possible, comparison of the information obtained with that obtained from precordial echocardiography.

RESULTS

Introduction of the probe was successful in 57 of the 58 patients. The only complication encountered was transient bradycardia during manipulation of the probe in a 2.2 kg baby. The adult (13 mm) probe was successfully used in children as small as 7.0 kg. Below this weight a smaller paediatric probe was required. In 56% of cases transoesophageal ultrasound provided information not obtained from the precordial approach. The technique was of particular value perioperatively and in the immediate postoperative period in neonates and infants and in the presence of valve prostheses and the investigation of mediastinal tumours in older children.

CONCLUSIONS

Transoesophageal echocardiography is a valuable additional investigative tool for children of all ages. It is of particular value when acquisition of precordial image is impaired around the time of and after operation and in children with prosthetic valves or mediastinal tumour. Image quality was superior with the adult probe and we recommend the use of this probe unless the patient's weight is below 7 kg, when a paediatric probe allows this technique to be used usefully and safely in babies as small as 2.2 kg.

Transesophageal echocardiography in infants and children with congenital heart disease

TEE applications for children and infants with congenital heart disease are now clinically established and TEE is being used in most major pediatric cardiovascular centers. This technology has evolved to the point that it is capable of providing diagnostic quality imaging, even for small infants. With expanding technology and increasing experience, new and more sophisticated applications will be found for pediatric TEE.

Transesophageal echocardiography detects thrombus formation not identified by transthoracic echocardiography after the Fontan operation

Transesophageal echocardiography demonstrated six instances of venous thrombus formation in the inferior vena cava, right atrium and caval-pulmonary anastomosis region in four children after a modified Fontan operation. Transthoracic surface echocardiography failed to identify these thrombi in five of the six cases because of the posterior location of the thrombus or imaging interference from surgical hardware. These thrombotic episodes occurred 2 days to 5 years after the Fontan operation in children 25 to 168 months of age. Clinical features of compromised cardiac performance with cyanosis or inadequate perfusion were present during four of the six episodes. In two patients, thrombi occurred around transvenous permanent atrial pacing leads. Therapy to eliminate thrombus included surgery (two cases), anticoagulation with warfarin (three cases) and streptokinase thrombolysis (one case). Disappearance of the thrombus was confirmed by transesophageal study in three of the four cases with follow-up echocardiography. Transesophageal echocardiographic demonstration of atrial and pulmonary thrombi that could not be seen by transthoracic imaging suggests that these thrombi occur with greater frequency in patients who have undergone the Fontan operation than was previously suspected.