Intraoperative transesophageal echocardiography using high-resolution biplane 7.5 MHz probes with continuous-wave Doppler capability in infants and children with tetralogy of Fallot

Accuracy of transesophageal echocardiography in the identification of postoperative intramural ventricular septal defects

BACKGROUND

Intramural ventricular septal defects (VSDs), residual interventricular communications occurring after repair of conotruncal defects, are associated with poor postoperative outcomes. The ability of intraoperative transesophageal echocardiography (TEE) to identify intramural VSDs has not yet been evaluated.

METHODS

Intraoperative TEE and postoperative transthoracic echocardiography (TTE) data in all patients undergoing all biventricular repair of conotruncal anomalies in our hospital between January 1, 2006, and June 30, 2013, were reviewed. The ability of TEE to accurately identify residual defects was assessed using postoperative TTE as the reference imaging modality.

RESULTS

Intramural VSDs occurred in 34 of 337 patients evaluated; 19 were identified by both TTE and TEE, and 15 were identified by TTE only. Sensitivity was 56% and specificity was 100% for TEE to identify intramural VSDs. Peripatch VSDs were identified in 90 patients by both TTE and TEE, in 53 by TTE only, and in 15 by TEE only, yielding a sensitivity of 63% and specificity of 92%. Of the VSDs requiring catheterization or surgical reintervention, 6 of 7 intramural VSDs and all 5 peripatch VSDs were identified by intraoperative TEE. TEE guided the intraoperative decision to return to cardiopulmonary bypass (CPB) in an attempt to close residual defects in 12 patients with intramural VSDs and in 4 patients with peripatch VSDs seen after initial CPB; of these, 10 intramural VSDs and all 4 peripatch VSDs resolved or became smaller on final intraoperative TEE.

CONCLUSIONS

TEE has modest sensitivity but high specificity for identifying intramural VSDs and can detect most defects requiring reintervention. Repeat attempts at closure in the index operation may successfully correct intramural VSDs identified by TEE.

Transesophageal Echocardiography in Tetralogy of Fallot

Transesophageal echocardiography (TEE) plays an important role in the anatomical, functional, and hemodynamic assessment of patients with congenital heart disease (CHD). This imaging approach has been applied to both children and adults with a wide range of cardiovascular malformations. Extensive clinical experience documents significant contributions, particularly in the perioperative setting. In fact, in the current medical era, many consider this technology to be an essential adjunct to surgical and anesthetic management in CHD. This review focuses on the applications of TEE in patients with tetralogy of Fallot (TOF), the most common form of cyanotic heart disease. Emphasis is given to the perioperative use of this imaging modality and benefits derived during the prebypass and postbypass periods. Limitations and pitfalls relevant to the TEE assessment in patients with this anomaly are also addressed.

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.

Reliability of intraoperative transesophageal echocardiography during Tetralogy of Fallot repair

There is limited information available concerning the accuracy of intraoperative transesophageal echocardiography (TEE) in predicting the extent of residual abnormalities after recovery from surgical repair of tetralogy of Fallot. Therefore, we investigated differences between the results of final postbypass TEE and those of postrecovery (mean, 6 days after surgery) transthoracic echocardiography in a total of 28 consecutive pediatric patients who underwent repair of tetralogy of Fallot with biplane or multiplane TEE. Both postbypass and postrecovery echocardiographic examinations included measurements of the right ventricle (RV)-main pulmonary artery (PA) and the main PA-branch PA peak instantaneous gradients, the degree of pulmonary valvar insufficiency, and color Doppler interrogation of the ventricular septum for residual defects. The RV-main PA gradient did not change significantly: 15 +/- 13 vs 18 +/- 14 mmHg (postbypass versus postrecovery, mean +/- SD). None of the patients had a decrease of > or = 10 mmHg; and only one patient had an increase of > or = 15 mmHg. There also was no change in the degree of pulmonary insufficiency (3.0 +/- 1.2 versus 3.1 +/- 1.1, using a scale of 0 to 4). Only one of the seven very small (< or = 2 mm) residual ventricular septal defects was not discovered during postbypass TEE. However, postrecovery transthoracic echocardiography detected significant branch PA stenosis (peak gradient, > or = 15 mmHg) in five patients (18%) that was not detected during postbypass TEE (P < 0.03). Of the branch PA stenoses that were not detected during TEE, four were left and one was right.

CONCLUSIONS

Postbypass TEE after tetralogy of Fallot repair reliably predicts residual postrecovery hemodynamic abnormalities, except for branch PA stenosis.

Transesophageal imaging of the mid to distal left pulmonary artery in congenital heart disease

We assessed how well transesophageal echocardiography (TEE) images the left pulmonary artery (LPA) in congenital heart disease (CHD). Seventy-nine consecutive patients with CHD were studied. Ideal imaging displayed the mid to distal LPA from the takeoff of the upper lobe artery through the second bifurcation. Imaging quality was graded from 1 (excellent) to 5 (not visualized). Imaging quality was excellent in 8 (10%) patients, good in 25 (32%), fair in 23 (29%), and poor in 12 (15%); the LPA was not visualized in 11 (14%) patients. Imaging grade averaged 2.9 +/- 1.2 (SD) and correlated poorly with weight (r = 0.24) but was better in patients without prior operation (grade 2.8 vs 3.3, P <.05). In 2 patients, TEE showed residual stenosis. Thus informative LPA imaging by TEE can be achieved in many patients with CHD and has the potential to change intraoperative or postoperative treatment.

Feasibility study: transesophageal echocardiography with a 10F (3.2-mm), multifrequency (5.5- to 10-MHz) ultrasound catheter in a small rabbit model

Transesophageal echocardiography (TEE) is useful in children with congenital heart defects. However, because of available probe size (>/=7 mm diameter), its use is limited to patients weighing more than 3 kg. The aim of this study was to determine the feasibility of TEE in a small animal model by using a 10F (3.2-mm) intravascular ultrasound tipped catheter with a monoplane (longitudinal) 5.5- to 10-MHz phased vector array transducer. Ten New Zealand White rabbits (400 to 3400 g; mean 1580 g) underwent TEE. With animals under general sedation, the probe was blindly introduced into the esophagus. All intracardiac and extracardiac structures were examined, and the images were stored and independently reviewed. All pertinent intracardiac and extracardiac structures were identified except in the 3 smallest rabbits (400 to 600 g). Doppler hemodynamics and color Doppler were possible in each animal. Frequency agility (5.5 to 10 MHz) facilitated optimization of image resolution and penetration. Certain transgastric, 4-chamber, and short-axis views were limited because of the monoplane array. No overt adverse effects were associated with the procedure. Diagnostic TEE can be performed in a small animal model with a 10F, 5.5- to 10-MHz phased vector array ultrasound catheter. Our study suggests that this system has potential in performing diagnostic TEE safely in small, even premature, neonates.

Double chambered right ventricle: delineation by multiplane transoesophageal echocardiography

Three consecutive patients (median age 5 years; median weight 15 kg) with double chambered right ventricle (DCRV) were studied by multiplane transoesophageal echocardiography (TOE), using a specially designed paediatric probe. Using a 30 degrees angulation from the longitudinal plane, the body and outflow tract of the right ventricle could be imaged with minimal foreshortening, allowing detailed description of the level and nature of obstruction. In all cases, angiography and subsequent surgical inspection confirmed the TOE findings. Multiplane TOE should avoid the necessity for angiography in the preoperative assessment of this unusual lesion.

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.