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Transesophageal Echocardiography in Pediatric Patients: Preliminary Results
Transesophageal Echocardiography in Pediatric Patients: Preliminary Results Jan Lam, MD, Rodolfo A. Neirotti, MD, Aagje Nijveld, MD, Jaap L. Schuller, MD, Connie M. Blom-Muilwijk, MD, and Cees A. Visser, MD, Amsterdam and Utrecht, The Netherlands
Transesophageal echocardiography was attempted in 59 pediatric patients with congenital heart disease in the operating room (n = 33) or during heart catheterization or in the intensive care unit (n = 26). Six different commercially available transducers were used with diameters ranging from 7 to 15 mm. Age ranged from 1 day to 16 years, and body weight ranged from 3.7 to 65 kg. Objectives of the study were to determine (1) minimum body weight in which transesophageal echocardiography with various probes is possible, (2) additional diagnostic value, and (3) potential applications. In three cases (one surgical and two nonsurgical) the probe could not be inserted. Minimum body weight was 17 to 20 kg for probes with a diameter of 2:13 mm and approximately 12 kg for the 11 mm probes. A 7 mm probe, on the other hand, could be inserted easily in all patients (including a neonate) in whom transesophageal echocardiography was attempted. In 11 of 56 patients, additional diagnostic information was obtained. Thus, transesophageal echocardiography is feasible in the pediatric age group provided that special probes are used in small children. Additional diagnostic information can be obtained, and the technique is of value during cardiac surgery or balloon interventions for evaluation of the efficacy of the procedure and for monitoring ventricular function. ( J AM Soc EcHo 1991;4:43-50.)
Transesophageal echocardiography has become an established technique for the evaluation of cardiac morp~ology and function in adult patients in whom transthoracic echocardiography is not satisfactory because of inability to get acoustic access to the heart. 1 However, there are currently only a few reports about this technique applied in children. 2 •3 This is mainly because of the size of the currently available transducers. Although children usually have adequate transcutaneous acoustic windows, transesophageal cchocardiography may be helpful during cardiac surgery or balloon dilations, or in those patients with inadequate acoustic access to retrosternal structures such as extra cardiac conduits. Furthermore, acoustic access can also be limited in the postoperative intensive care situation. From the departments of Pediatric Cardiology, Pediatric Cardiac Surgery, Pediatric Cardiac Anesthesiology, and Cardiology, Academical Medical Centre, Amsterdam, and the Interuniversitv Cardiological Institute of The Netherlands (ICIN), Utrecht. ' Reprint requests: Jan Lam, MD, Academical Medical Centre, G82l5, Meibcrgdrcef 9, llOS AZ Amsterdam, The Netherlands. 27/l/24960
The present study was undertaken to determine the value and limitations of transesophageal echocardiography in children.
PATIENTS AND METHODS
Between February 1988 and May 1990, transesophageal echocardiography was attempted in 59 patients who had various types of congenital heart disease. The age range of these patients was from 1 day to 16 years, and body weight ranged from 3.7 to 65 kg. All patients but one were under general anesthesia during the procedure. Insertion of the probe was performed after the intubation by the anesthesiologist with a laryngoscope under direct vision. Six types of transducers were used, one type in each patient. A pediatric gastroenterologist inspected all of the different probes once and gave advice regarding minimum body weight for each particular probe. The three largest probes were regarded to be "adult" size: the 14 mm 5 MHz Hewlett-Packard 43
44
Journal of the American Society of Echocardiographv
Lam et al.
Table I
Surgical procedures No. of
Procedure
Fontan operation Repair of tetralogy of Failor Closure of secundum-type atrial septal defect Ross operation Ligation of persistent ductus arteriosus Mitral valve reconstruction Ascending aorta replacement Muscular resection in hypertrophic obstructive cardiomyopathy Correction of double-chambered right ventricle Closure of ventricular septal defect Correction of double-outlet right ventricle Exploration of pericarditis Rastelli operation Arterial switch operation Coarctectomy Annuloplasty in severe tricuspid valve regurgitation Enucleation of discrete subaortic stenosis Closure of atrial septal defect in Ebstein 's malformation Reimplantation of left coronary artery originating from pulmonary artery Aortic valve replacement TOTAL
patients
3 6 4 2 2
32
transducer (Hewlett-Packard Company, Palo Alto, California), the 13 mm 3.75 MHz Toshiba transducer (Toshiba/ Sonolayer, Tustin, California), and the 15 mm Diasonics transducer (Diasonics, Inc., South San Francisco, California) (programmable as 5 and 7.5 MHz). The remaining three probes, the 11 mm 5 MHz Diasonics transducer, the standard 11 mm 5 MHz Aloka probe and the 7 mm 5 MHz Aloka pediatric probe (Aloka Company, Ltd., Tokyo, Japan) were regarded to be more suitable for small children. All of these transducers have two-dimensional and color-coded Doppler facilities. Continuous-wave Doppler echocardiography was available with only the Diasonics equipment. In 32 of 33 patients the probe could be inserted during cardiac surgery after intubation; it was left in situ throughout the procedure (Table 1). During the period of cardioplcgic arrest the probe was disconnected from the echocardiographic equipment. At the end of surgical procedure the examination was repeated. No pharmacologic agents were used to return the blood pressure to normal, especially for the transesophageal echocardiographic examination. In case of valvular regurgitation, jet width and jet length were compared with the preoperative findings. The
manipulation of the probe and the interpretation of the transesophageal echocardiographic study was performed by the pediatric cardiologist. In 20 of 22 patients the probe was successfully inserted during various types of diagnostic or interventional catheterization (Table 2) and in four other patients for additional diagnostic purposes. Of these four patients, one patient was admitted after resuscitation because of ventricular fibrillation of unknown cause. With transthoracic echocardiography an abnormal coronary artery pattern could not be ruled out. However, with transesophageal echocardiography a normal branching pattern of the proximal coronary arteries could be demonstrated. Two other patients had Marfan's syndrome and chest pain, and transthoracic echocardiography could not exclude an intimal tear in the ascending aorta. However, transesophageal echocardiography revealed no abnormalities. The fourth patient underwent cardioversion because of atrial fibrillation. Transesophageal echocardiography was performed to rule out left atrial thrombus. In all patients, transthoracic echocardiography was performed before and after transesophageal echocardiography. All transesophageal echocardiographic examinations were combined with color flow mapping. The surgical patients received 20 mg/kg cephalothin sodium before the insertion of the probe, but in the nonsurgical cases no antibiotic prophylaxis was given. No patient had a history of esophageal disease.
RESULTS
In three patients (5.1%) the probe could not be inserted. One patient, a 14-year-old boy with a body weight of 60 kg, had an oropharyngeal disorder caused by a previous tracheostomy, and the HewlettPackard probe could not be introduced. In another patient with a body weight of 20 kg, the 15 mm Diasonics probe could not be inserted. The third failure was in a 3-year-old girl with a body weight of 10 kg in whom the standard 11 mm Aloka probe could not be inserted. During these three failed attempts no other probes were available. Forty-three patients were studied with the adult-sized probes. In four of these patients, body weight ranged from 17 to 20 kg. In these cases insertion and manipulation was somewhat hampered, although the intracardiac anatomy could be demonstrated in all of them. In the larger children (body weight > 20 kg) manipulation was comparable with adults. Nine patients (weight range, 12 to 60 kg) were studied with the
Volume 4 Number I )anuarv-Fcbruary 1991
TEE in pediatric patients
45
Table 2 Transesophageal echocardiography in the catheterization laboratory No. of
Diagnosis
Peripheral pulmonary stenosis Recurrent coarctation Valvular pulmonary stenosis Valvular aortic stenosis* Transposition of the great arteries Secundum-type atrial septal defect plus valvular pulmonary stenosis Pulmonary atresia plus ventricular septal defect Congenitally corrected transposition plus pulmonary valve stenosis Univentricular heart, status after atrial septectomy plus banding of the pulmonary artery Tetralogy of Fallot
Procedure
Angioplasty Angioplasty Valvuloplasty Valvuloplasty Balloon septostomy
patients
3 3 2 5
Diagnostic catheterization
Diagnostic catheterization Diagnostic catheterization Diagnostic catheterization
Diagnostic catheterization
2 20
TOTAL
*One patient had associated coarctation of the aorta.
ll mm probes, and manipulation was easy in all cases. Four patients (weight range, 3.7 to 12 kg) were studied with the Aloka pediatric probe; insertion and manipulation were easy. Diagnostic Aspects
In all patients in whom the probe was successfully inserted, excellent visualization was obtained of intracardiac structures and flow by use of previously described techniques. 4 The atrial anatomy, the atrioventricular valves, the posterior atrioventricular valve, and the right ventricular anterior wall were particularly well delineated. The four-chamber and foreshortened long-axis views (or comparable views in patients with a univentricular heart), could be easily obtained in all patients. The short-axis view of the left ventricle at midpapillary level was somewhat difficult to obtain, in particular with the larger probes, and this was only seriously attempted when there was concern about ventricular function. The pulmonary artery was demonstrated in three of the first 14 patients of the series but in 34 of the next 42 patients. However, in two patients with known persistent ductus arteriosus, this structure could not be demonstrated. Although the pulmonary artery was well visualized in both cases, no turbulent blood flow could be demonstrated with color flow mapping. With use of the adult probes, the right ventricular outflow tract could not usually be visualized in detail,
in contrast to the smaller Aloka probes (Figure 1). In five patients with isolated or associated coarctation of the aorta, the coarctation was demonstrated in the short-axis view; this is not possible with transthoracic echocardiography. Also, short-axis views were obtained in other anomalies of the great arteries, such as the pulmonary artery bifurcation after the Lecompte procedure in transposition of the great arteries (Figure 2). In ll of 56 patients, 16 features, important from the diagnostic point of view, were either newly detected or better described, compared with transesophageal echocardiographic findings (Table 3). Observations During Surgery
Thirty-two patients were studied during various surgical procedures (Table 1). Residual valvular incompetence occurring immediately after surgery, to a degree that additional surgery had to be considered, was present in three patients. In one patient undergoing mitral valve annuloplasty caused by mitral valve prolapse and anulus dilation, residual regurgitation was judged to be so severe that mitral valve replacement was necessary during the same procedure. In a patient with tetralogy of Fallot, combined with subarterial ventricular septal defect and aortic regurgitation caused by a bicuspid aortic valve, the degree of regurgitation appeared to be somewhat increased at the end of surgery, persisting during follow-up studies as moderate regurgitation. This concerned one of our first transesophageal echocar-
46
Lam eta!.
Journal of the American Society of Echocardiography
A, Transesophag eal echocardiogra m demonstrating right ventricular outflow tract in a patient with tetralogy of Fallot (body weight, 16 kg). B, Same view in a patient with tetralogy ofFallot (body weight, 12 kg). This view also demonstrates the infundibular gradient over the right ventricular outflow tract (maximum velocity, 3m/sec). Sample volume is placed at the valvular level. LPA, Left pulmonary artery; PA, pulmonary artery; Ao, aortic root; R VOT, right ventricular outflow tract. Figure 1
diographic studies and it was decided to accept this regurgitation. In retrospect, however, it might have been more appropriate to go on bypass support again to inspect the aortic valve. In another patient, with ascending aorta dilation and severe aortic regurgitation, ascending aorta replacement was performed with resuspension of the native aortic valve. Severe aortic regurgitation was present at the end of surgery. It was decided to accept this, but severe aortic regurgitation persisted during follow-up studies. Retrospectively, it would have been more appropriate to
replace the native valve during the same operation. This patient underwent aortic valve replacement 1 year later. In a patient who was operated on because of a secundum-ty pe atrial septal defect and pulmonary stenosis, a small apical ventricular septal defect was detected with transesophageal echocardiog raphy that was not demonstrabl e with transthoracic echocardiography. The defect was not treated. In a patient with tetralogy ofF allot a small residual ventricular septal defect was detected immediately
Volume 4 Number 1 january-February 1991
TEE in pediatric patients 4 7
Figure 2 Transesophageal echocardiogram demonstrating short-axis views through the great arteries in a neonate with transposition of the great arteries before the operation (A) and after the Lecompte procedure (B). PA, Pulmonary artery; Ao, aorta.
after closure. The defect was not repaired during the same procedure. Monitoring of Myocardial Function
All but one patient could be weaned off bypass support easily. That patient revealed extreme myocardial dysfunction at the end of a surgical procedure. The first impression was that this was irreversible. However, with continuous transesophageal echocardiographic monitoring it became apparent that ventricular contractions were present as long as bypass was running, but as soon as bypass was stopped, the heart became almost akinetic. This observation prompted
the surgeon to insert an intra-aortic balloon pump despite the small body size of the patient (weight, 20 kg). The patient eventually recovered. This was the second patient in whom transesophageal echocardiography had a direct impact on intraoperative decision making. Failures of Demonstrating Efficacy of Cardiac Surgery
In all but four patients, the efficacy of the cardiac repair could be demonstrated. In two of those four patients, postoperative Doppler echocardiographic studies demonstrated a sue-
48
Lam et al.
journal of the Socictv of Echocardiographv
At11crican
Figure 3 A, Transesophageal echocardiogram obtained during atrial balloon scprostomy in a neonate (same patient as in Figure 2). During septosromv, balloon (arrows) passes the interatrial septum. B, Color flow mapping and pulsed Doppler tracings after the procedure showing left-to-right shunting at atrial level. Sample volume is placed in the interatrial septum. LA, Left atrium; RA, right atrium.
cessful repair, but this could not be demonstrated intraoperatively. In both cases the operation consisted of resection of cardiac muscle; one patient had hypertrophic obstructive cardiomyopathy and the other patient had a two-chambered right ventricle. In the first case the failure might have been because an adequate long-axis view of the left ventricular outflow tract could not be obtained with transesophageal echocardiography. In the case of the two-chambered right ventricle, the failure may be explained by the absence of continuous-wave Doppler mode facilities during that study. The other two patients in whom the efficacy of cardiac repair could not be demonstrated intra-
operatively concerned the previously mentioned patients with persistent ductus arteriosus. Thus, of 32 surgical patients, the efficacy of the procedure could be demonstrated in 28 patients. In two patients there was a direct impact on intraoperative surgical decision making, and this would have been possible retrospectively in another two patients. Transesophageal Echocardiography During Catheter Interventions
Transesophageal echocardiographic monitoring was used in combination with and also during fluoroscopy, but occasionally the probe overprojected the
Volume 4 Number 1 January-February 1991
region of interest. This procedure therefore required close cooperation between the transesophageal echocardiographic investigator and the physician who performed the catheter manipulation. In the five patients undergoing aortic valvuloplasty, we did not demonstrate any change in valvular morphology. Of interest in this respect is the fact that during follow-up studies the next day there was no apparent reduction in pressure gradient. In retrospect, these observations could have probably allowed us to use a larger balloon. In two patients undergoing a balloon dilation of a stenosis in the proximal part of the right pulmonary artery, an apparent increase in diameter could be demonstrated, together with increased perfusion of the right lung with ventilation-perfusion scanning the next day. Three patients underwent balloon dilation of a recurrent coarctation. In two of those patients, in whom coarctectomy had been performed more than 10 years earlier, no increase in diameter could be noted. In the third patient, a 6-year-old boy (body weight, 20 kg) who underwent a subclavian flap angioplasty in the neonatal period, a clear increase in diameter was noted. Follow-up studies were in agreement with these observations in all three cases. Decision making was clearly influenced in one patient who was scheduled for balloon dilation of a stenotic pulmonary valve. Transesophageal echocardiography revealed an associated secundum-type atrial septal defect that had not been previously detected with transthoracic echocardiography. For that reason, the dilation catheter was not inserted and the patient was treated surgically. The atrial septal defect was confirmed during surgery. One neonate with transposition of the great arteries had balloon atrioseptostomy with transesophageal echocardiographic monitoring (Figure 3). In three other patients, two of them undergoing balloon dilation of a stenotic pulmonary valve and one undergoing balloon dilation of a peripheral pulmonary stenosis, these lesions could not be demonstrated by transesophageal echocardiography _ Complications One patient (body weight, 20 kg), studied with the 14 mm Hewlett-Packard probe, had minor bleeding, demonstrated only by some blood staining on the probe. This was probably related to the fact that, in this case, the probe was inserted after the heparinization. Ironically, this was the previously mentioned surgical patient with severe myocardial dysfunction who benefited more from the transesophageal echocardiographic monitoring than any other patient in this series. No other complications were noted.
TEE in pediatric patients 49
Table 3 Newly detected diagnostic information No. of
Anomaly
Secundum type atrial septal defect Tricuspid regurgitation (significant) Mitral regurgitation Aortic regurgitation Conduit flow after Fontan operation Dilated right coronary artery Ventricular septal defect Local thickening of right atrial wall Demonstration aortic-mitral valve continuity Atrial isomerism (right) TOTAL
patients
4 2 2
l 2
l l l
16
Follow-up was available in all patients. Bacterial endocarditis did not develop in any patient.
DISCUSSION
This study demonstrated that transesophageal echocardiography with commercially available probes is also feasible in children. Although pediatric gastroenterologists often perform gastroscopies in children who have not been sedated, anesthesia is recommended. When the adult-sized probes (diameter ::::13 mm) are used, the body weight of the patient should be approximately 20 kg or more. On the other hand, the Aloka pediatric probe can be used even in neonates. Because the larger probes contain more elements or facilities that are like continuous-wave Doppler echocardiography, the larger children (body weight > 20 kg) can be better studied with those probes unless the right ventricular outflow tract is the main subject of interest. As in adults, additional diagnostic information can be obtained with transesophageal echocardiography in the pediatric population. Imaging of the right ventricular anterior wall and the atrial anatomy is excellent. The latter aspect is very helpful in determining the atrial situs in congenital heart disease. Atrioventricular regurgitant jets can be detected very accurately. However, for visualization of the aortic arch and the right ventricular outflow tract in children, transthoracic echocardiography is superior to transesophageal echocardiography. Also, a good long-axis view of the left ventricle is difficult to obtain with transesophageal echocardiography. An important indication for transesophageal echocardiography is the application during cardiac surgery, particularly in those cases
50
Journal of the American Society of Echocardiography
Lam eta!.
where residual lesions, such as residual intracardiac shunting, incompetence of the atrioventricular or aortic valves, or myocardial dysfunction, are anticipated. Pulmonary valve regurgitation cannot be accurately evaluated with transesophageal echocardiography. Of the closed heart cases transesophageal echocardiography appears to be beneficial in the repair of coarctation of the aorta combined with left ventricular dysfunction. In cases such as aorticopulmonary shunting or patent ductus arteriosus ligation, transesophageal echocardiography can only be beneficial if the abnormal pulmonary artery flow pattern can be demonstrated. Although important information can also be obtained during cardiac surgery by epicardial echocardiography, 5 the disadvantage of the latter technique is that the operation has to be interrupted, and a device has to be brought into the operation field on the beating heart. In addition, monitoring cannot be performed continuously, as with transesophageal echocardiography. The latter apsect is important in monitoring myocardial function in both cardiac and noncardiac surgery. Transesophageal echocardiography can be of value during interventions, in particular during balloon dilation. When a balloon valvuloplasty is performed, transesophageal echocardiography offers the possibility of continuous monitoring of cardiac morphology and function by a separate investigator who is not involved with electrocardiogram monitoring, invasive pressure tracings, or fluoroscopy. The investigator can stay outside the radiation field, and transesophageal echocardiographic monitoring does not need to be interrupted during fluoroscopy. Furthermore, information can be obtained that will help to determine whether or not a larger balooon should be used. 6 •7 Because invasive evaluation of the efficacy of a balloon dilation may require the exchange of catheters, with risk of dislocation of the guide wire, all additional information is important. Limitations in this respect are the absence of continuous-wave Doppler facilities in most types of presently available equipment and the limited number of scanning planes, making estimation of gradients inaccurate or impossible. Interventions during which transesophageal echocardiography may be of value include balloon dilation of valvular aortic stenosis, supravalvular pulmonic stenosis, obstructed Mustard baffles, coarctation of the aorta, atrial balloon septostomy, and catheter occlusions of atrial septal defects.
From a diagnostic viewpoint, transesophageal echocardiography is of value in those cases in which transthoracic echocardiography is not satisfactory. In neonates, this will be the case only in patients with associated malformations, such as omphalocele. In older children, however, a poor acoustic window is somewhat more common, for instance, after conduit operations or Mustard and Senning operations. In those cases, it is not always possible to perform a complete transthoracic echocardiographic study, and transesophageal echocardiography can be complementary. 8 The application of transesophageal echocardiography in children will undoubtedly expand further when more smaller probes become available. We thank Dr. M. A. Taams for performing one transesophageal echocardiographic study; Mrs. B. van de Burg, Dr. L. J. Lubbers, and Dr. M. S. J. Naeff for performing most of the transthoracic echocardiographic studies; Dr. 0. Daniels, Radboud Hospital, Nijmegen, The Netherlands, for giving permission to study three patients; and Dr. J. A. J. M. Taminiau, pediatric gastroenterologist, for giving advice. We also thank Dr. M. S. J. Naeff for her comments.
REFERENCES l. Visser CA, Koolen JJ, van den Brink RBA, van Wezel HB, Dunning A]. Uses of transesophageal echocardiography out-
2. 3. 4.
5. 6. . 7.
8.
side the operating room. Am J Cardiac Imaging 1989;3:3444. Cyran SE, Kimball TR, Meyer RA, et al. Efficacy of intraoperative transesophageal echocardiography in children with congenital heart disease. Am J Cardiol 1989;63:594-8. Rirter SB, Thys D. Pediatric transesophageal color flow imaging: smaller probes for smaller hearts. Echocardiography 1989;6:431-40. Seward JB, Khandheria BK, Oh ]K, et al. Transesophageal echocardiography: technique, anatomic correlations, implementation and clinical applications. Mayo Clin Proc 1988;63: 649-80. van Herwerden LA, Gussenhoven WJ, Roelandt ], et al. Intraoperative epicardial two-dimensional echocardiography. Eur Heart J 1986;7:386-95. Cyran SE, Kimball TR, Schwartz DC, Meyer RA, Steed RD, Kaplan S. Evaluation ofballoon aortic valvuloplasty with transesophageal echocardiography. Am Heart J 1988;2:460-2. Todt M, Erbel R, Pop T, Bednarczyk I, Drexler M, Meyer J. Dilatation einer supravalvularen Pulmonalisstenose bei transosophagealem echokardiogrpahischem MonitoringKissing-Balloon-Technik. Z Kardiol 1988;77:385-8. Sutherland GR. The role of transesophageal echocardiography in adolescents and adults with congenital heart disease. In: Erbel R, Brennecke R, Khandheria BK, Meyer J, Seward JB, Tajik AJ, eds. Transesophageal cchocardiography. Berlin: Springer Verlag, 1989:47-57.
Transesophageal echocardiography was attempted in 59 pediatric patients with congenital heart disease in the operating room (n = 33) or during heart catheterization or in the intensive care unit (n = 26). Six different commercially available transducers were used with diameters ranging from 7 to 15 mm. Age ranged from 1 day to 16 years, and body weight ranged from 3.7 to 65 kg. Objectives of the study were to determine (1) minimum body weight in which transesophageal echocardiography with various probes is possible, (2) additional diagnostic value, and (3) potential applications. In three cases (one surgical and two nonsurgical) the probe could not be inserted. Minimum body weight was 17 to 20 kg for probes with a diameter of 2:13 mm and approximately 12 kg for the 11 mm probes. A 7 mm probe, on the other hand, could be inserted easily in all patients (including a neonate) in whom transesophageal echocardiography was attempted. In 11 of 56 patients, additional diagnostic information was obtained. Thus, transesophageal echocardiography is feasible in the pediatric age group provided that special probes are used in small children. Additional diagnostic information can be obtained, and the technique is of value during cardiac surgery or balloon interventions for evaluation of the efficacy of the procedure and for monitoring ventricular function. ( J AM Soc EcHo 1991;4:43-50.)
Transesophageal echocardiography has become an established technique for the evaluation of cardiac morp~ology and function in adult patients in whom transthoracic echocardiography is not satisfactory because of inability to get acoustic access to the heart. 1 However, there are currently only a few reports about this technique applied in children. 2 •3 This is mainly because of the size of the currently available transducers. Although children usually have adequate transcutaneous acoustic windows, transesophageal cchocardiography may be helpful during cardiac surgery or balloon dilations, or in those patients with inadequate acoustic access to retrosternal structures such as extra cardiac conduits. Furthermore, acoustic access can also be limited in the postoperative intensive care situation. From the departments of Pediatric Cardiology, Pediatric Cardiac Surgery, Pediatric Cardiac Anesthesiology, and Cardiology, Academical Medical Centre, Amsterdam, and the Interuniversitv Cardiological Institute of The Netherlands (ICIN), Utrecht. ' Reprint requests: Jan Lam, MD, Academical Medical Centre, G82l5, Meibcrgdrcef 9, llOS AZ Amsterdam, The Netherlands. 27/l/24960
The present study was undertaken to determine the value and limitations of transesophageal echocardiography in children.
PATIENTS AND METHODS
Between February 1988 and May 1990, transesophageal echocardiography was attempted in 59 patients who had various types of congenital heart disease. The age range of these patients was from 1 day to 16 years, and body weight ranged from 3.7 to 65 kg. All patients but one were under general anesthesia during the procedure. Insertion of the probe was performed after the intubation by the anesthesiologist with a laryngoscope under direct vision. Six types of transducers were used, one type in each patient. A pediatric gastroenterologist inspected all of the different probes once and gave advice regarding minimum body weight for each particular probe. The three largest probes were regarded to be "adult" size: the 14 mm 5 MHz Hewlett-Packard 43
44
Journal of the American Society of Echocardiographv
Lam et al.
Table I
Surgical procedures No. of
Procedure
Fontan operation Repair of tetralogy of Failor Closure of secundum-type atrial septal defect Ross operation Ligation of persistent ductus arteriosus Mitral valve reconstruction Ascending aorta replacement Muscular resection in hypertrophic obstructive cardiomyopathy Correction of double-chambered right ventricle Closure of ventricular septal defect Correction of double-outlet right ventricle Exploration of pericarditis Rastelli operation Arterial switch operation Coarctectomy Annuloplasty in severe tricuspid valve regurgitation Enucleation of discrete subaortic stenosis Closure of atrial septal defect in Ebstein 's malformation Reimplantation of left coronary artery originating from pulmonary artery Aortic valve replacement TOTAL
patients
3 6 4 2 2
32
transducer (Hewlett-Packard Company, Palo Alto, California), the 13 mm 3.75 MHz Toshiba transducer (Toshiba/ Sonolayer, Tustin, California), and the 15 mm Diasonics transducer (Diasonics, Inc., South San Francisco, California) (programmable as 5 and 7.5 MHz). The remaining three probes, the 11 mm 5 MHz Diasonics transducer, the standard 11 mm 5 MHz Aloka probe and the 7 mm 5 MHz Aloka pediatric probe (Aloka Company, Ltd., Tokyo, Japan) were regarded to be more suitable for small children. All of these transducers have two-dimensional and color-coded Doppler facilities. Continuous-wave Doppler echocardiography was available with only the Diasonics equipment. In 32 of 33 patients the probe could be inserted during cardiac surgery after intubation; it was left in situ throughout the procedure (Table 1). During the period of cardioplcgic arrest the probe was disconnected from the echocardiographic equipment. At the end of surgical procedure the examination was repeated. No pharmacologic agents were used to return the blood pressure to normal, especially for the transesophageal echocardiographic examination. In case of valvular regurgitation, jet width and jet length were compared with the preoperative findings. The
manipulation of the probe and the interpretation of the transesophageal echocardiographic study was performed by the pediatric cardiologist. In 20 of 22 patients the probe was successfully inserted during various types of diagnostic or interventional catheterization (Table 2) and in four other patients for additional diagnostic purposes. Of these four patients, one patient was admitted after resuscitation because of ventricular fibrillation of unknown cause. With transthoracic echocardiography an abnormal coronary artery pattern could not be ruled out. However, with transesophageal echocardiography a normal branching pattern of the proximal coronary arteries could be demonstrated. Two other patients had Marfan's syndrome and chest pain, and transthoracic echocardiography could not exclude an intimal tear in the ascending aorta. However, transesophageal echocardiography revealed no abnormalities. The fourth patient underwent cardioversion because of atrial fibrillation. Transesophageal echocardiography was performed to rule out left atrial thrombus. In all patients, transthoracic echocardiography was performed before and after transesophageal echocardiography. All transesophageal echocardiographic examinations were combined with color flow mapping. The surgical patients received 20 mg/kg cephalothin sodium before the insertion of the probe, but in the nonsurgical cases no antibiotic prophylaxis was given. No patient had a history of esophageal disease.
RESULTS
In three patients (5.1%) the probe could not be inserted. One patient, a 14-year-old boy with a body weight of 60 kg, had an oropharyngeal disorder caused by a previous tracheostomy, and the HewlettPackard probe could not be introduced. In another patient with a body weight of 20 kg, the 15 mm Diasonics probe could not be inserted. The third failure was in a 3-year-old girl with a body weight of 10 kg in whom the standard 11 mm Aloka probe could not be inserted. During these three failed attempts no other probes were available. Forty-three patients were studied with the adult-sized probes. In four of these patients, body weight ranged from 17 to 20 kg. In these cases insertion and manipulation was somewhat hampered, although the intracardiac anatomy could be demonstrated in all of them. In the larger children (body weight > 20 kg) manipulation was comparable with adults. Nine patients (weight range, 12 to 60 kg) were studied with the
Volume 4 Number I )anuarv-Fcbruary 1991
TEE in pediatric patients
45
Table 2 Transesophageal echocardiography in the catheterization laboratory No. of
Diagnosis
Peripheral pulmonary stenosis Recurrent coarctation Valvular pulmonary stenosis Valvular aortic stenosis* Transposition of the great arteries Secundum-type atrial septal defect plus valvular pulmonary stenosis Pulmonary atresia plus ventricular septal defect Congenitally corrected transposition plus pulmonary valve stenosis Univentricular heart, status after atrial septectomy plus banding of the pulmonary artery Tetralogy of Fallot
Procedure
Angioplasty Angioplasty Valvuloplasty Valvuloplasty Balloon septostomy
patients
3 3 2 5
Diagnostic catheterization
Diagnostic catheterization Diagnostic catheterization Diagnostic catheterization
Diagnostic catheterization
2 20
TOTAL
*One patient had associated coarctation of the aorta.
ll mm probes, and manipulation was easy in all cases. Four patients (weight range, 3.7 to 12 kg) were studied with the Aloka pediatric probe; insertion and manipulation were easy. Diagnostic Aspects
In all patients in whom the probe was successfully inserted, excellent visualization was obtained of intracardiac structures and flow by use of previously described techniques. 4 The atrial anatomy, the atrioventricular valves, the posterior atrioventricular valve, and the right ventricular anterior wall were particularly well delineated. The four-chamber and foreshortened long-axis views (or comparable views in patients with a univentricular heart), could be easily obtained in all patients. The short-axis view of the left ventricle at midpapillary level was somewhat difficult to obtain, in particular with the larger probes, and this was only seriously attempted when there was concern about ventricular function. The pulmonary artery was demonstrated in three of the first 14 patients of the series but in 34 of the next 42 patients. However, in two patients with known persistent ductus arteriosus, this structure could not be demonstrated. Although the pulmonary artery was well visualized in both cases, no turbulent blood flow could be demonstrated with color flow mapping. With use of the adult probes, the right ventricular outflow tract could not usually be visualized in detail,
in contrast to the smaller Aloka probes (Figure 1). In five patients with isolated or associated coarctation of the aorta, the coarctation was demonstrated in the short-axis view; this is not possible with transthoracic echocardiography. Also, short-axis views were obtained in other anomalies of the great arteries, such as the pulmonary artery bifurcation after the Lecompte procedure in transposition of the great arteries (Figure 2). In ll of 56 patients, 16 features, important from the diagnostic point of view, were either newly detected or better described, compared with transesophageal echocardiographic findings (Table 3). Observations During Surgery
Thirty-two patients were studied during various surgical procedures (Table 1). Residual valvular incompetence occurring immediately after surgery, to a degree that additional surgery had to be considered, was present in three patients. In one patient undergoing mitral valve annuloplasty caused by mitral valve prolapse and anulus dilation, residual regurgitation was judged to be so severe that mitral valve replacement was necessary during the same procedure. In a patient with tetralogy of Fallot, combined with subarterial ventricular septal defect and aortic regurgitation caused by a bicuspid aortic valve, the degree of regurgitation appeared to be somewhat increased at the end of surgery, persisting during follow-up studies as moderate regurgitation. This concerned one of our first transesophageal echocar-
46
Lam eta!.
Journal of the American Society of Echocardiography
A, Transesophag eal echocardiogra m demonstrating right ventricular outflow tract in a patient with tetralogy of Fallot (body weight, 16 kg). B, Same view in a patient with tetralogy ofFallot (body weight, 12 kg). This view also demonstrates the infundibular gradient over the right ventricular outflow tract (maximum velocity, 3m/sec). Sample volume is placed at the valvular level. LPA, Left pulmonary artery; PA, pulmonary artery; Ao, aortic root; R VOT, right ventricular outflow tract. Figure 1
diographic studies and it was decided to accept this regurgitation. In retrospect, however, it might have been more appropriate to go on bypass support again to inspect the aortic valve. In another patient, with ascending aorta dilation and severe aortic regurgitation, ascending aorta replacement was performed with resuspension of the native aortic valve. Severe aortic regurgitation was present at the end of surgery. It was decided to accept this, but severe aortic regurgitation persisted during follow-up studies. Retrospectively, it would have been more appropriate to
replace the native valve during the same operation. This patient underwent aortic valve replacement 1 year later. In a patient who was operated on because of a secundum-ty pe atrial septal defect and pulmonary stenosis, a small apical ventricular septal defect was detected with transesophageal echocardiog raphy that was not demonstrabl e with transthoracic echocardiography. The defect was not treated. In a patient with tetralogy ofF allot a small residual ventricular septal defect was detected immediately
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TEE in pediatric patients 4 7
Figure 2 Transesophageal echocardiogram demonstrating short-axis views through the great arteries in a neonate with transposition of the great arteries before the operation (A) and after the Lecompte procedure (B). PA, Pulmonary artery; Ao, aorta.
after closure. The defect was not repaired during the same procedure. Monitoring of Myocardial Function
All but one patient could be weaned off bypass support easily. That patient revealed extreme myocardial dysfunction at the end of a surgical procedure. The first impression was that this was irreversible. However, with continuous transesophageal echocardiographic monitoring it became apparent that ventricular contractions were present as long as bypass was running, but as soon as bypass was stopped, the heart became almost akinetic. This observation prompted
the surgeon to insert an intra-aortic balloon pump despite the small body size of the patient (weight, 20 kg). The patient eventually recovered. This was the second patient in whom transesophageal echocardiography had a direct impact on intraoperative decision making. Failures of Demonstrating Efficacy of Cardiac Surgery
In all but four patients, the efficacy of the cardiac repair could be demonstrated. In two of those four patients, postoperative Doppler echocardiographic studies demonstrated a sue-
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Lam et al.
journal of the Socictv of Echocardiographv
At11crican
Figure 3 A, Transesophageal echocardiogram obtained during atrial balloon scprostomy in a neonate (same patient as in Figure 2). During septosromv, balloon (arrows) passes the interatrial septum. B, Color flow mapping and pulsed Doppler tracings after the procedure showing left-to-right shunting at atrial level. Sample volume is placed in the interatrial septum. LA, Left atrium; RA, right atrium.
cessful repair, but this could not be demonstrated intraoperatively. In both cases the operation consisted of resection of cardiac muscle; one patient had hypertrophic obstructive cardiomyopathy and the other patient had a two-chambered right ventricle. In the first case the failure might have been because an adequate long-axis view of the left ventricular outflow tract could not be obtained with transesophageal echocardiography. In the case of the two-chambered right ventricle, the failure may be explained by the absence of continuous-wave Doppler mode facilities during that study. The other two patients in whom the efficacy of cardiac repair could not be demonstrated intra-
operatively concerned the previously mentioned patients with persistent ductus arteriosus. Thus, of 32 surgical patients, the efficacy of the procedure could be demonstrated in 28 patients. In two patients there was a direct impact on intraoperative surgical decision making, and this would have been possible retrospectively in another two patients. Transesophageal Echocardiography During Catheter Interventions
Transesophageal echocardiographic monitoring was used in combination with and also during fluoroscopy, but occasionally the probe overprojected the
Volume 4 Number 1 January-February 1991
region of interest. This procedure therefore required close cooperation between the transesophageal echocardiographic investigator and the physician who performed the catheter manipulation. In the five patients undergoing aortic valvuloplasty, we did not demonstrate any change in valvular morphology. Of interest in this respect is the fact that during follow-up studies the next day there was no apparent reduction in pressure gradient. In retrospect, these observations could have probably allowed us to use a larger balloon. In two patients undergoing a balloon dilation of a stenosis in the proximal part of the right pulmonary artery, an apparent increase in diameter could be demonstrated, together with increased perfusion of the right lung with ventilation-perfusion scanning the next day. Three patients underwent balloon dilation of a recurrent coarctation. In two of those patients, in whom coarctectomy had been performed more than 10 years earlier, no increase in diameter could be noted. In the third patient, a 6-year-old boy (body weight, 20 kg) who underwent a subclavian flap angioplasty in the neonatal period, a clear increase in diameter was noted. Follow-up studies were in agreement with these observations in all three cases. Decision making was clearly influenced in one patient who was scheduled for balloon dilation of a stenotic pulmonary valve. Transesophageal echocardiography revealed an associated secundum-type atrial septal defect that had not been previously detected with transthoracic echocardiography. For that reason, the dilation catheter was not inserted and the patient was treated surgically. The atrial septal defect was confirmed during surgery. One neonate with transposition of the great arteries had balloon atrioseptostomy with transesophageal echocardiographic monitoring (Figure 3). In three other patients, two of them undergoing balloon dilation of a stenotic pulmonary valve and one undergoing balloon dilation of a peripheral pulmonary stenosis, these lesions could not be demonstrated by transesophageal echocardiography _ Complications One patient (body weight, 20 kg), studied with the 14 mm Hewlett-Packard probe, had minor bleeding, demonstrated only by some blood staining on the probe. This was probably related to the fact that, in this case, the probe was inserted after the heparinization. Ironically, this was the previously mentioned surgical patient with severe myocardial dysfunction who benefited more from the transesophageal echocardiographic monitoring than any other patient in this series. No other complications were noted.
TEE in pediatric patients 49
Table 3 Newly detected diagnostic information No. of
Anomaly
Secundum type atrial septal defect Tricuspid regurgitation (significant) Mitral regurgitation Aortic regurgitation Conduit flow after Fontan operation Dilated right coronary artery Ventricular septal defect Local thickening of right atrial wall Demonstration aortic-mitral valve continuity Atrial isomerism (right) TOTAL
patients
4 2 2
l 2
l l l
16
Follow-up was available in all patients. Bacterial endocarditis did not develop in any patient.
DISCUSSION
This study demonstrated that transesophageal echocardiography with commercially available probes is also feasible in children. Although pediatric gastroenterologists often perform gastroscopies in children who have not been sedated, anesthesia is recommended. When the adult-sized probes (diameter ::::13 mm) are used, the body weight of the patient should be approximately 20 kg or more. On the other hand, the Aloka pediatric probe can be used even in neonates. Because the larger probes contain more elements or facilities that are like continuous-wave Doppler echocardiography, the larger children (body weight > 20 kg) can be better studied with those probes unless the right ventricular outflow tract is the main subject of interest. As in adults, additional diagnostic information can be obtained with transesophageal echocardiography in the pediatric population. Imaging of the right ventricular anterior wall and the atrial anatomy is excellent. The latter aspect is very helpful in determining the atrial situs in congenital heart disease. Atrioventricular regurgitant jets can be detected very accurately. However, for visualization of the aortic arch and the right ventricular outflow tract in children, transthoracic echocardiography is superior to transesophageal echocardiography. Also, a good long-axis view of the left ventricle is difficult to obtain with transesophageal echocardiography. An important indication for transesophageal echocardiography is the application during cardiac surgery, particularly in those cases
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Lam eta!.
where residual lesions, such as residual intracardiac shunting, incompetence of the atrioventricular or aortic valves, or myocardial dysfunction, are anticipated. Pulmonary valve regurgitation cannot be accurately evaluated with transesophageal echocardiography. Of the closed heart cases transesophageal echocardiography appears to be beneficial in the repair of coarctation of the aorta combined with left ventricular dysfunction. In cases such as aorticopulmonary shunting or patent ductus arteriosus ligation, transesophageal echocardiography can only be beneficial if the abnormal pulmonary artery flow pattern can be demonstrated. Although important information can also be obtained during cardiac surgery by epicardial echocardiography, 5 the disadvantage of the latter technique is that the operation has to be interrupted, and a device has to be brought into the operation field on the beating heart. In addition, monitoring cannot be performed continuously, as with transesophageal echocardiography. The latter apsect is important in monitoring myocardial function in both cardiac and noncardiac surgery. Transesophageal echocardiography can be of value during interventions, in particular during balloon dilation. When a balloon valvuloplasty is performed, transesophageal echocardiography offers the possibility of continuous monitoring of cardiac morphology and function by a separate investigator who is not involved with electrocardiogram monitoring, invasive pressure tracings, or fluoroscopy. The investigator can stay outside the radiation field, and transesophageal echocardiographic monitoring does not need to be interrupted during fluoroscopy. Furthermore, information can be obtained that will help to determine whether or not a larger balooon should be used. 6 •7 Because invasive evaluation of the efficacy of a balloon dilation may require the exchange of catheters, with risk of dislocation of the guide wire, all additional information is important. Limitations in this respect are the absence of continuous-wave Doppler facilities in most types of presently available equipment and the limited number of scanning planes, making estimation of gradients inaccurate or impossible. Interventions during which transesophageal echocardiography may be of value include balloon dilation of valvular aortic stenosis, supravalvular pulmonic stenosis, obstructed Mustard baffles, coarctation of the aorta, atrial balloon septostomy, and catheter occlusions of atrial septal defects.
From a diagnostic viewpoint, transesophageal echocardiography is of value in those cases in which transthoracic echocardiography is not satisfactory. In neonates, this will be the case only in patients with associated malformations, such as omphalocele. In older children, however, a poor acoustic window is somewhat more common, for instance, after conduit operations or Mustard and Senning operations. In those cases, it is not always possible to perform a complete transthoracic echocardiographic study, and transesophageal echocardiography can be complementary. 8 The application of transesophageal echocardiography in children will undoubtedly expand further when more smaller probes become available. We thank Dr. M. A. Taams for performing one transesophageal echocardiographic study; Mrs. B. van de Burg, Dr. L. J. Lubbers, and Dr. M. S. J. Naeff for performing most of the transthoracic echocardiographic studies; Dr. 0. Daniels, Radboud Hospital, Nijmegen, The Netherlands, for giving permission to study three patients; and Dr. J. A. J. M. Taminiau, pediatric gastroenterologist, for giving advice. We also thank Dr. M. S. J. Naeff for her comments.
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