Usefulness of biplane transesophageal echocardiography in neonates, infants and children with congenital heart disease

The use of echocardiography in congenital heart surgery and intervention

Echocardiography has revolutionized the management of pediatric and adult heart disease, especially in the diagnosis of congenital heart defects. Although the early methods of echocardiography (M-mode and Doppler imaging) were limited in their ability to define the defect in question, the advent of 2D, and now 3D, imaging have clearly equaled or surpassed traditional methods of diagnosis (e.g., noninvasively obtained plain chest radiographs and electrocardiograms) and invasive tests (e.g., cardiac catheterization and angiography). Confidence in the images obtained using echocardiography has continued to increase, with many patients referred for corrective or palliative surgery on the basis of echocardiographic imaging alone. Echocardiography has eliminated the need, decreased the frequency, or improved the timing or performance of invasive studies in other patients. Specifically, it is used to definitively diagnose a cardiac defect and any associated lesions. It will also provide quantitative information for the assessment of the hemodynamic severity of the lesion. This review outlines the manner in which echocardiography is used to plan and guide congenital heart surgery or intervention, along with some of the advantages and disadvantages (pitfalls) of which to be aware. The use of echocardiography within the cardiac catheterization or surgical theater, as well as in the intensive care unit, is discussed, as is the use of echocardiography as a means of monitoring recovery and follow-up following cardiac surgery. Finally, the authors discuss who is best qualified or suited to perform these tests.

Evaluation of shunt flow by multiplane transesophageal echocardiography in adult patients with isolated patent ductus arteriosus

The role of multiplane (M) transesophageal echocardiography (TEE) in the diagnosis of isolated patent ductus arteriosus (PDA) in adults and its effectiveness in the assessment of the pulmonary to systemic flow ratio were evaluated and compared with those obtained from cardiac catheterization examination. Eleven consecutive patients, ranging from 17 to 56 years old (mean of 29.5 +/- 12.0), with clinically suspected PDA were subjects of this study. A complete transthoracic echocardiographic study was performed in each patient before MTEE. MTEE with Doppler color flow mapping showed clear visualization of a ductal structure between the descending aorta and pulmonary artery with a continuous turbulent mosaic flow suggestive of PDA in all 11 patients. The pulmonary/systemic flow and vascular resistance ratios obtained by echocardiography and cardiac catheterization correlated well (r = 0.8732, P =.0004; r = 0.623, P =.04, respectively). This study demonstrated that MTEE combined with transthoracic echocardiography examination is an accurate noninvasive means in the diagnosis of PDA and assessment of the pulmonary to systemic flow and vascular resistance ratios in adult patients.

Miniaturized transesophageal echocardiography in newborn infants

BACKGROUND AND METHODS

A miniaturized 5.5 to 10 MHz, phased-array, single longitudinal plane transducer mounted on a 3.3-mm diameter catheter (miniaturized transesophageal echocardiography [TEE]) may overcome mechanical limitations of standard pediatric transesophageal probes. We evaluated whether the miniaturized TEE probe could define clinically relevant anatomy in 17 infants who weighed less than 6 kg.

RESULTS

Twenty-two studies were performed in 17 infants without complication, weighing 2.1 to 5.6 kg. Twenty of twenty-two studies were diagnostic. Pediatric biplane TEE was not possible in 13 studies. Lack of horizontal plane imaging with miniaturized TEE made evaluation difficult in patients with atrioventricular septal defect.

CONCLUSION

Miniaturized TEE provided diagnostic intraoperative TEE in the majority of infants studied and may allow broader and safer application of TEE to neonates and small infants.

Magnetic resonance phase-shift velocity mapping in pediatric patients with pulmonary venous obstruction

OBJECTIVES

This study evaluated the accuracy, advantages and clinical efficacy of magnetic resonance (MR) phase-shift velocity mapping, in delineating the site and the hemodynamic severity of pulmonary venous (PV) obstruction in patients with congenital heart disease (CHD).

BACKGROUND

Magnetic resonance phase-shift velocity mapping of normal pulmonary veins and of obstructed PV pathways have been previously reported in a mainly adult population.

METHODS

The study population (33 pts) underwent MR phase-shift velocity mapping of their PV pathways. These results were compared with cardiac catheterization and Doppler echocardiography data.

RESULTS

The study population (0.4 to 19.5 years) consisted of a study group (PV pathway obstruction, n = 7) and a control group (no PV obstruction, n = 26). No patients had any left-to-right shunt lesions. The MR imaging displayed precise anatomical detail of the pulmonary veins. Phase velocities in the control group ranged from 20 to 71 cm/s, whereas velocities in the study group ranged from 100 to 250 cm/s (p = 0.002). The MR phase velocities (154 +/- 0.53 cm/s) compared favorably with Doppler echocardiography (147 +/- 0.54 cm/s), (r = 0.76; p = 0.05). The MR velocity mapping was 100% specific and 100% sensitive in detecting PV obstruction, although the absolute gradient measurements among MR phase mapping, echocardiographic Doppler and catheterization did not show statistically significant correlation.

CONCLUSIONS

In the absence of any associated left-to-right shunt lesions, PV velocities of 100 cm/s and greater indicated significant obstruction. The MR phase-shift velocity mapping, together with MR spin echocardiography and MR angiography, provides comprehensive anatomic and physiologic data that may obviate the need for further invasive studies.

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.

Incidence of complications in pediatric transesophageal echocardiography: experience in 1650 cases

The purpose of this study was to tabulate the complications encountered in 1650 patients who underwent pediatric transesophageal echocardiography. The occurrence of complications and their type and severity were prospectively recorded. The patients had a mean age of 3.6 years (range 1 day to 21 years) and a mean weight of 17.2 kg (range 1.6 to 118 kg). Of the 1650 cases, 1534 were intraoperative. Most patients studied (97%) had congenital heart disease. Complications occurred in 52 (3.2%) of the 1650 patients. Failure to insert the probe occurred in 13 (0.8%) patients; if those cases are not counted as complications, the incidence of overall complications falls to 2.4%. Airway obstruction occurred in 14 (1%) patients, right mainstem advancement of the endotracheal tube in 3 (0.2%), inadvertent tracheal extubation in 8 (0.5%), vascular compression in 10 (0.6%), and single additional complications in 4 (0.2%). No significant bleeding, arrhythmias, esophageal injuries, or deaths occurred. Failure to insert the probe and airway complications occurred predominantly and significantly in smaller subjects. It is concluded that the incidence of complications during pediatric transesophageal echocardiography is low.

Advances in echocardiographic diagnostic modalities for the pediatrician

Two-dimensional Doppler echocardiography has become the primary diagnostic tool in the assessment of infants and children with congenital and acquired heart disease. Over the past 10 years, specialized echocardiographic techniques have also become critical components in the evaluation and treatment of these patients. Using fetal echocardiography enables us to image the heart early in gestation and have begun to understand those lesions that can develop and progress in utero. Transesophageal echocardiography has allowed you to image the patient with congenital heart disease during repair in the operating room and in the cardiac catheterization laboratory so that adequacy of the repair can be assess and any residual lesions addressed immediately. Both of these specialized techniques are discussed in detail, with a brief overview at the three-dimensional future of echocardiography in the pediatric patient.

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.

Intraoperative Transgastric Echo Assessment During Left Ventricular Outflow Tract Surgery: A Reliable Predictor of Residual Obstruction

Standard transesophageal echocardiography (TEE) views of the left ventricular outflow tract (LVOT) are limited by poor Doppler beam alignment with the peak velocity of flow. Transgastric imaging allows well-aligned continuous-wave Doppler interrogation of the LVOT and was attempted during intraoperative TEE in all children undergoing LVOT surgery at Children's Hospital of Wisconsin. Thirty-eight patients, ranging in age from 2 days to 18 years (median, 5.2 years) and in weight from 2.9 to 100 kg (median, 16.7 kg), had TEE during surgery to resect membranous or fibromuscular subaortic obstruction (20 patients), valvuloplasty for aortic stenosis/insufficiency (13 patients), aortoplasty for supravalvar stenosis (one patient), or repair/replacement for aortic insufficiency (four patients). In four patients, transgastric images of the LVOT could not be obtained. Intraoperative Doppler gradients identified severe residual obstruction (mean, 67 +/- 13.5 mmHg) after surgery in seven patients; six of these patients underwent immediate repeat operation with subsequent adequate relief, and one patient required later aortoventriculoplasty for persistent annular/valvar obstruction. All other patients had successful LVOT reconstruction with intraoperative Doppler gradients ranging from 0 to 46 mmHg, and none required early repeat operation. Good correlation was found between the intraoperative transgastric gradient (mean, 25.8 +/- 17.7 mmHg) and the early postoperative transthoracic echo gradient (mean, 21.8 +/- 21.4 mmHg). In addition, there was consistent agreement in the assessment of aortic insufficiency between the transesophageal and transthoracic studies. We conclude that transgastric Doppler assessment of the LVOT is a critical component of intraoperative monitoring during LVOT surgery and is a reliable predictor of residual obstruction.

MRI and echocardiography in children: how do they compare?

Clearly, both echocardiography and MRI play vital roles in the diagnosis and management of children with congenital heart defects. 2-D Doppler echocardiography is very easy to use in a vast array of clinical situations. The accuracy of the anatomic and hemodynamic findings are well accepted. In comparative studies, 2-D Doppler echocardiography appears preferable for intracardiac anatomy, whereas MRI appears preferable for extracardiac anatomy. In certain patients, Doppler echocardiography may not be able to optimally obtain the anatomic or hemodynamic information, and MRI should be used in these particular cases.

The surgeon's use of transesophageal echocardiography

Transesophageal echocardiography has become an instrumental diagnostic modality for the accurate evaluation of cardiac and aortic anatomy and function. Multiplanar technology has facilitated improved visualization of structures and enhanced TEE over TTE in many situations. Care of the trauma patient and critically ill patient is improved with the appropriate and timely performance of TEE. Education, certification, credentialing, and determination of competency are areas that need to be addressed continually in the future.

Myocardial effects of isoflurane in healthy infants and small children. Assessment by continuous oesophageal aortic blood flow echo-Doppler

BACKGROUND

In paediatric healthy patients and in real peroperative conditions, the cardiovascular effects of isoflurane have been poorly described.

METHODS

We have evaluated the myocardial effects of 1% end-expired concentration (EEC) of isoflurane in 25 healthy infants or small children undergoing superficial surgical therapy for small burns with a continuous aortic blood flow echo-Doppler device. Aortic blood flow (ABF) was measured with a small oesophageal probe specially designed for infants. The aortic flowmeter was connected with satellite devices to visualize the haemodynamic profile variations during the isoflurane inhalation period.

RESULTS

Isoflurane significantly decreased ABF and increased pre-ejection period/left ventricular ejection time (PEP/LVET), when compared with control values previously recorded 5 min after induction with halothane-fentanyl and atracurium (respectively, 80 +/- 7%, mean +/- SD; P < 0.001 and 111 +/- 11%; P = 0.017, 5 min after EEC of isoflurane reached 1%, then respectively, 75 +/- 12%; P < 0.001 and 119 +/- 16%; P < 0.001, at the end of the isoflurane inhalation period). These variations reversed to a great extent when isoflurane was switched off (97 +/- 17% for ABF; P = 0.08 and 105 +/- 12% for PEP/LVET; P = 0.75). Among the usual parameters, 1% EEC of isoflurane caused no significant changes in heart rate, moderately decreased mean arterial pressure (successively, 88 +/- 12%; P = 0.045 and 87 +/- 19%; P = 0.049), but belatedly decreased end-tidal CO2 pressure (87 +/- 11% at the end of the inhalation period (P < 0.001) which persisted 5 min after isoflurane was turned off (90 +/- 11%; P < 0.001)).

CONCLUSIONS

These findings suggest that isoflurane can transiently depress cardiac function in healthy infants.

Diagnostic accuracy and role of intraoperative biplane transesophageal echocardiography in pediatric patients with left ventricle outflow tract lesions

OBJECTIVES

To define the lesion-specific role of biplane transesophageal echocardiography in children with left ventricular outflow tract obstructive lesions, the diagnostic accuracy of transthoracic and transesophageal images were compared, and the impact of transesophageal echocardiography on perioperative management was evaluated.

BACKGROUND

The reported high postoperative recurrence of left ventricular outflow tract obstructive lesion can be due to its incomplete surgical relief. A full preoperative definition of the lesions would aid in better surgical outcome. The complexity and spectrum of such lesions provide opportunity to evaluate the role of a recently available biplane transesophageal pediatric probe in its diagnosis and surgical management.

METHODS

In 16 consecutive patients (11 male patients) with left ventricular outflow tract obstructive lesions and with a mean age of 7.9 +/- 5.7 years (range 0.25 to 20.0 years) and a mean weight of 29 +/- 19 kg (range 4 to 66 kg), the morphologic and hemodynamic findings of standard preoperative transthoracic and intraoperative biplane transesophageal echocardiography were compared with surgical and cardiac catheterization findings (in seven patients) for the diagnostic accuracy and impact on the surgical management of the lesions.

RESULTS

Based on the levels of agreement, transesophageal echocardiography demonstrated higher diagnostic sensitivity (chi-squared analysis = 13.4 < 0.001) to the presence and extent of associated lesions (septal hypertrophy, multiple fibromuscular insertions, involvement of aortic and mitral valves not revealed by transthoracic imaging) and trend toward higher sensitivity (Fisher's exact p = 0.17) to primary morphologic diagnoses (abnormal chordal attachments, prolapsed aortic cusp, and tunnel-like outflow tract obstructive lesions missed by transthoracic imaging). As a result of these factors, intraoperative transesophageal imaging changed the surgical plan in 25% of the patients and modified it in an additional 25% of the patients.

CONCLUSIONS

Transesophageal echocardiography can be a reliable diagnostic tool and has an important role in the surgical management of left ventricular outflow tract lesions in children.

Continuous oesophageal aortic blood flow echo-Doppler measurement during general anaesthesia in infants

PURPOSE

Invasive haemodynamic monitoring during general anaesthesia in infants is usually limited to very high risk operations, such as cardiac surgery. Nevertheless, different surgical procedures and/or anaesthetic techniques justify additional monitoring for children, as for adults. The aim of this preliminary study was to evaluate the feasibility of using a new echo-Doppler device (Dynemo 3000) capable of measuring continuous aortic blood flow during general anaesthesia in infants.

METHODS

Aortic blood flow (ABF) was measured with a small oesophageal probe designed for newborns and infants. The aortic flowmeter was connected with satellite devices to visualise the haemodynamic profile which included ABF, pre-ejection period (PEPi), left ventricular ejection time (LVETi), mean arterial pressure, heart rate, stroke volume and systemic vascular resistance. Twelve infants, aged 8-26 mo, undergoing surgery under general anaesthesia were successively included in the evaluation of this device. Isoflurane (1% end-expired concentration) was introduced to maintain anaesthesia after induction with halothane, midazolam, fentanyl and atracurium.

RESULTS

Correct positioning of the probe was easily obtained in all cases and the recording quality was excellent, whatever the operative position. Recordings of haemodynamic data showed some myocardial depression from isoflurane: decreased ABF (indexed to body surface area) and lengthened PEP/LVET (2.24 +/- 0.53 L.min-1.m-2 and 0.32 +/- 0.05 respectively, before introduction of isoflurane and 1.71 +/ 0.53 L.min-1.m-2 (P = 0.027) and 0.39 +/- 0.06 (P = 0.007) with isoflurane).

CONCLUSION

These preliminary results suggest that this continuous ABF echo-Doppler device may be valuable for peri anaesthetic monitoring in infants.

Pediatric multiplane transesophageal echocardiography in congenital heart disease: new possibilities with a miniaturized probe

In recent years, transducers for multiplane Doppler echocardiography have demonstrated their superior imaging performance in adult patients. To date, the size of these probes has limited their use in pediatric patients. In this article, we report our initial experience with a recently developed miniaturized transducer with all conventional imaging and Doppler modalities. The study focused primarily on imaging performance by comparing standard biplane images with those obtained in oblique planes. The investigations were carried out intraoperatively or during interventional catheterization in patients with congenital heart disease. We observed no complications in a study population of 15 children (weight range of 5 to 63 kg and an age range of 96 days to 11 years). The probe was easy to handle and provided excellent images. Additional information was obtained in several cases and documentation of clinical findings was easier because an optimal image plane almost always could be displayed. We concluded that pediatric multiplane Doppler echocardiography has considerably improved investigative performance compared with the conventional monoplane or biplane studies normally available for this age group. In neonates, however, investigation with the multiplane technique is limited by the size of the patient.

An introduction to transoesophageal echocardiography: I. Basic principles

PURPOSE

The purpose of this review is to introduce the uninitiated to transoesophageal echocardiography (TEE): how it works, and what it can do. Sufficient detail is provided to serve as a reference guide to anaesthetists already using TEE in clinical practice.

SOURCE

A Medline search of English language literature up to and including August 1995 was conducted using the key words echocardiography and TEE. Reference echocardiography textbooks were also utilized in the preparation of this review.

PRINCIPLE FINDINGS

All information available from TEE is derived from either cardiac imaging or analysis of blood flow velocity using various Doppler modes. To understand the diagnostic capabilities of TEE we review clinically useful views of the heart as well as modes of cardiac imaging. Sufficient basic physics is presented to allow proper use of adjustment features on the echocardiography machine so that cardiac imaging can be optimized. Available Doppler modes are explained along with an overview of their clinical applications. Figures illustrating clinically useful views obtainable with omniplane TEE are included along with colour prints demonstrating clinical applications of colour flow Doppler.

CONCLUSION

TEE is becoming increasingly important in the management of cardiac patients for cardiac and non-cardiac surgery. An understanding of the capabilities of the technology as well as the underlying physics allows the anaesthetist to glean the most information from this valuable technique, both quantitatively and qualitatively.

Diagnostic accuracy of transesophageal echocardiography for detecting patent ductus arteriosus in adolescents and adults

To compare the accuracy of transesophageal echocardiography (TEE) with that of transthoracic echocardiography (TTE) in the detection of patent ductus arteriosus (PDA) in the adolescent and the adult, 40 patients with PDA and 50 patients with other congenital heart diseases were studied. All echocardiograms were recorded before cardiac catheterization and surgery. The echocardiographic diagnosis of PDA was made by direct visualization of a shunt flow in the duct. A mosaic flow in the pulmonary artery without direct visualization of the duct was considered possible but not definitely diagnostic of PDA. TEE showed greater sensitivity and negative predictive value than TTE (97% vs 42%, and 98% vs 68%, respectively; p < 0.001) in confirming the diagnosis of PDA. The specificity and positive predictive value in establishing the diagnosis of PDA were the same for both techniques. In the subgroup of patients with Eisenmenger's syndrome, the sensitivity of TEE and TTE in confirming diagnosis of PDA was 100% and 12% (p < 0.01), respectively. The sensitivity of monoplane and biplane TEE in the diagnosis of PDA was comparable (95% and 100%, respectively; p = NS). In conclusion, TEE was highly sensitive and specific in detecting PDA in adolescents and adults. It was also highly valuable for detecting the cause of pulmonary hypertension in patients with Eisenmenger's syndrome.

Biplane intraoperative transesophageal echocardiography in congenital heart disease

OBJECTIVE

To evaluate the accuracy, value, and safety of biplane intraoperative transesophageal echocardiography (TEE) in patients with congenital cardiac malformations.

DESIGN

We reviewed the results of the first 104 consecutive biplane intraoperative TEE examinations performed during the repair of congenital heart defects at the Mayo Clinic.

MATERIAL AND METHODS

TEE results were analyzed for accuracy of diagnosis, effect on the surgical procedure, and associated complications. In a subjective analysis, the relative contributions and advantages of each imaging plane (transverse and longitudinal) were also assessed.

RESULTS

Biplane TEE had "significant impact" on intraoperative management in 17 of 104 examinations (16.3%). Preoperative TEE altered the planned procedure in 11 patients (10.6%). Postbypass biplane TEE led to immediate revision of the initial repair in nine patients (8.7%). Patients who underwent modified Fontan operations or subaortic resections had the greatest frequency of significant impact (40% [P = 0.006] and 33% [P = 0.03], respectively). No major complications were associated with TEE. For a complete examination, use of both imaging planes was necessary in all the patients studied.

CONCLUSION

Biplane TEE is an accurate, valuable, and safe addition to the perioperative care of patients with congenital heart disease. Although intraoperative TEE is not needed in all operations for congenital heart disease, we recommend that biplane intraoperative TEE be performed routinely during modified Fontan procedures, subaortic resections, and other intracardiac operations for complex congenital cardiac malformations.

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.