Gregory K. Sorensen

Transesophageal Echocardiography During Repair of Congenital Cardiac Defects: Identification of Residual Problems Necessitating Reoperation

One advantage of intraoperative transesophageal echocardiographic (TEE) evaluation during surgery for congenital heart disease is detection of suboptimal repairs, thus providing the opportunity to return to cardiopulmonary bypass (CPB) to repair residual defects. The purpose of this study was to evaluate the impact of TEE on decisions to return to CPB. Two-hundred-thirty infants and children with a variety of defects were studied with size-appropriate TEE probes. Patients were grouped by anatomic defect or surgical procedure for which TEE was requested. After CPB, pre- and post-CPB TEE anatomic, functional, and flow evaluations were compared. TEE findings prompted a return to CPB to repair residual defects in 17 of 230 (7.4%) patients. By diagnosis, return to CPB occurred in 9 of 28 (32%) patients with left ventricular outflow tract obstruction, 5 of 78 (6.4%) patients with ventricular septal defect, 1 of 16 (6%) patients with switch-repaired transposition, 1 of 32 (3%) with aortic valve disease, and 1 of 3 with double outlet right ventricle. All post-CPB diagnoses were confirmed during reoperation. Although post-CPB TEE provided reassuring information in patients with other diagnoses, TEE impact on return to CPB appears to be significant in a small group of primary diagnoses. The sensitivity and specificity of TEE determination of the need for reoperation were 89% and 100%, respectively. By identifying the site, severity, and mechanism of residual problems, TEE offers substantial utility in detection of residual problems in need of reoperation.

Guidelines for Transesophageal Echocardiography in Children

Derek A. Fyfe, MD, PhD, Samuel B. Ritter, MD, A. Rebecca Snider, MD, Norman H . Silverman, MD, J. Geoffrey Stevenson, MD, Gregory Sorensen, MD, Gregory Ensing, MD, Achi Ludomirsky, MD, David J. Sahn, MD, Dan Murphy, MD, Donald Hagler, MD, and Gerald R. Marx, MD, Charleston, South Carolina, New York, New York, Durham, North Carolina, San Francisro, California, Seattle, Washington, Indianapolis, Indiana, Ann Arbor, Michigan, Portland, Oregon, Cleveland, Ohio, Rochester, Minnesota, and Boston, Massachusetts

Effects of the Thromboxane Synthetase Inhibitor, Dazmegrel (UK 38,485), on Pulmonary Gas Exchange and Hemodynamics in Neonatal Sepsis

ABSTRACT. Group B streptococcal (GBS) sepsis produces arterial hypoxemia in newborns. In piglets we previously found that hypoxemia develops because of increased ventilation perfusion heterogeneity, and reduced mixed venous pO2 occurring in association with decreased pulmonary blood flow. We hypothesize that increased thromboxane A2 (TxA2) synthesis mediates the immediate alterations in gas exchange found in GBS sepsis. We studied 18 anesthetized, ventilated piglets before, during, and after a 30-min infusion of 2 × 109 colony forming units/kg of GBS. Nine piglets were pretreated with 8 mg/ kg of dazmegrel (DAZ), a TxA2 synthetase inhibitor, and nine animals received GBS without DAZ pretreatment. Pulmonary and systemic arterial pressures, pulmonary vascular resistance, pulmonary blood flow, respiratory gas tensions, intrapulmonary shunt, and SD of pulmonary blood flow, an index of ventilation perfusion mismatching, were measured. Systemic and pulmonary arterial levels of thromboxane B2 and 6-keto-PGF1α were also measured. The sham-treated animals showed the expected rise in pulmonary arterial pressure from 12 ± 3 to 29 ± 7 torr, (p<0.02). By comparison, the animals pretreated with DAZ did not demonstrate pulmonary arterial hypertension and had a delay in the fall in pulmonary blood flow until 2 h postinfusion. Arterial PO2 did not decline significantly after the GBS infusion in the DAZ-pretreated animals; the untreated animals showed a significant fall in pO2 from baseline. There was no significant change in intrapulmonary shunt or SD of pulmonary blood flow compared to baseline in the DAZ-pretreated animals. The elevation in thromboxane B2 occurring with GBS sepsis did not occur in the DAZ-pretreated animals. We conclude that TxA2 in part mediates the immediate gas exchange and pulmonary hemodynamic abnormalities during GBS sepsis. Inhibition of TxA2 synthetase results in preservation of normal pulmonary gas exchange and a delay in the fall in Qp following GBS infusion.

Proper probe size for pediatric transesophageal echocardiography

L arge “adult size” transesophageal echocardiographic (TEE) probes have been used for examination of older children and adults with congenital and acquired heart disease. More recently, smaller “pediatric” TEE probes have become available, allowing TEE examination of smaller subjects. Although references in published reports indicate that the larger probes “can be used safely in larger children (>20 kg),” and that pediatric probes have been used in infants weighing as little as 2.4 to 6.5 kg,1-3 little information exists regarding the safety of widespread use of probes of different size in the pediatric population. We reviewed a consecutive series of 346 TEE examinations at Children’s Hospital and Medical Center Seattle. Most of the patients (332 of 346) were examined intraoperatively, with the remainder examined in the intensive care unit or cardiac catheterization laboratory. Examinations conformed to Guidelines established for TEE examination in children.4 At each examination, report forms were completed, including data regarding patient and probe size, ease of probe insertion, and complications. These reports form the data base for this review. Ultrasound instrumentation used in this series included Siemens SI-1200, Hewlett-Packard Sonos 1000, and Toshiba SSH-140 systems. The pediatric probes had shaft diameters of 6.0 to 7.0 mm, and distal transducer tip dimensions of 7 X 10 mm or 6 X 13 mm. The “adult” probes had a shaft diameter of 9.8 mm, with distal tip dimension of 11 X 15 mm. These probes, previously disinfected with Cidex (Johnson & Johnson, Arlington, Texas), were placed in a sterile latex sheath (Civco, Kalowna, Iowa) whose tip had been filled with ultrasonic gel (Aquasonic, Parker Labs, Orange, New Jersey). The gel-filled sheath was massaged to distribute the gel in a thin layer within the sheath, and to prevent any bulbous accumulation of the gel within the sheath. The sheath-covered probes were lightly lubricated (Surgilube, E. E Fougera, Melville, New York), and inserted manually, usually without laryngoscopic visualization. Upon removal of the TEE probes, the external aspect of the sheath was inspected, and the report form completed. Complications, which included inability to insert the TEE probe, were noted. Ease of insertion was graded on a 1 to 5 scale (1 = easy insertion, 5 = most dtficult). Statistical analysis was performed using Fisher’s exact test (Fish 6, Wm. Engels, University of Wisconsin, Madison, Wisconsin).

Hemodynamic effects of amrinone in children after fontan surgery

After Fontan repair in children, we performed a prospective, open-label study to evaluate the effect of amrinone on pulmonary vascular resistance (PVRI). Eight patients who underwent the Fontan repair had baseline arterial pressure, left atrial pressure, central venous pressure, and cardiac output measured postoperatively. Hemodynamic measurements were repeated after amrinone 4.5 mg/kg. The PVRI tended to decrease, but the change was not statistically significant. Although the systemic vascular resistance decreased to 802 +/- 222 from 941 +/- 191 dynes centered dot s centered dot cm-5 centered dot m-2 (P < 0.05), mean arterial blood pressure was unchanged. Cardiac index (3.8 +/- 1.2 to 4.7 +/- 1.6 L centered dot min-1 centered dot m-2) and stroke volume index (23.6 +/- 6.7 to 30.5 +/- 8.1 mL centered dot beat-1 centered dot m-2) increased, and heart rate decreased (160 +/- 21 to 151 +/- 24 bpm) (P < 0.05). Colloid transfusion during amrinone bolus administration was 13.9 mL/kg. The mean serum amrinone concentration was 4.2 micro gram/mL at the end of bolus and clearance was 2.24 mL centered dot kg-1 centered dot min-1. Arrhythmias and thrombocytopenia were not noted. We conclude that amrinone administration is effective in increasing cardiac output in children who have undergone a Fontan repair. (Anesth Analg 1996;82:241-6)

Left Ventricular Outflow Tract Obstruction: An Indication for Intraoperative Transesophageal Echocardiography

Transesophageal echocardiography (TEE) provides detailed anatomic imaging of both discrete and complex forms of left ventricular outflow tract (LVOT) obstruction, and Doppler techniques provide additional information regarding the site, mechanism, and severity of the obstruction. Because the transaortic surgical approach to LVOT obstruction often provides limited direct visualization during surgery, we sought to evaluate the utility of intraoperative TEE during surgery for LVOT obstruction. We tested the hypotheses that intraoperative TEE would (1) be useful in defining the level and nature of LVOT obstruction, (2) serve to direct the surgical approach, (3) define the adequacy of relief of LVOT obstruction, and (4) detect surgical complications. Study population consisted of a consecutive series of 27 infants and children undergoing surgery for LVOT obstruction. Patient age ranged from 0.5 to 17.9 years, and weight from 5.4 to 71.2 kg. In 14 patients LVOT obstruction resulted from a discrete membrane, whereas 13 had complex forms of LVOT obstruction. Fully anesthetized and monitored patients were examined with 5 MHz TEE probes appropriate to the size of the patient. In the 14 patients with discrete LVOT obstruction, discrete membranes were identified by TEE in all; gradients ranged from 36 to 75 mm Hg. In 13 of 14 patients, postbypass TEE demonstrated removal of the membrane and excellent relief of gradients. In one of these patients, TEE demonstrated a small ventricular septal defect acquired during resection; the patient was returned to bypass for closure. In one patient, return to bypass for further resection of LVOT obstruction was prompted by TEE demonstration of a high residual gradient. In the 13 patients with complex LVOT obstruction, TEE demonstrated the complexity of LVOT obstruction in all. Gradients ranged from 4 to 95 mm Hg. Although this information was used in surgical planning, five patients had high residual gradients after bypass and underwent further resection. An additional two were returned to bypass for mitral valve replacement. Overall, 8 of 27 patients (29.6%) were returned to bypass based on TEE demonstration of residual anatomic or hemodynamic abnormalities. This occurred significantly more frequently in complex LVOT obstruction than in discrete LVOT obstruction (p = 0.045). We conclude that intraoperative TEE has substantial utility in the demonstration of site, mechanism, and severity of LVOT obstruction and for surgery designed to relieve LVOT obstruction. We believe that TEE should be an integral part of surgical management of LVOT obstruction.

Intraoperative transesophageal echocardiography of coronary artery fistulas.

Coronary artery fistula is a rare abnormality but one with substantial surgical importance, as operation abolishes the fistulous shunt volume, progressive coronary dilatation, and potential coronary steal. Prior reports emphasize the utility of direct inspection on cardiopulmonary bypass, with visualization of drainage of blood or cardioplegia from the fistulous connection, to define the drainage site. We report 3 patients in whom intraoperative transesophageal echocardiography was used for precise localization of the fistulous drainage site, selective demonstration of vessels feeding the fistulas, and documentation of abolition of fistulous flow, all without need for cardiopulmonary bypass. In addition, the technique provides for continuous monitoring of ventricular function, providing the opportunity to detect inadvertent ischemic effects of ligation. This approach appears to have considerable utility.

Teaching Successful Central Venous Cannulation in Infants and Children: Audio Doppler Versus Anatomic Landmarks

OBJECTIVEnTo determine if vein localization with an audio Doppler increases successful central venous cannulation and decreases complications in infants and children when performed by inexperienced operators, compared with vein localization by anatomic landmarks (ALs).nnnDESIGNnA prospective cohort of infants and children undergoing central venous cannulation for cardiac surgery.nnnSETTINGnA university-affiliated childrens hospital with a pediatric anesthesia fellowship program.nnnPARTICIPANTSnAll infants and children undergoing cardiac surgery between July 1, 1996, and January 1, 1997.nnnINTERVENTIONSnSubjects had central venous catheters (CVCs) placed by an anesthesia fellow by either ALs or audio-Doppler localization of the veins.nnnMEASUREMENTS AND MAIN RESULTSnEighty-four children were studied. Internal jugular vein (IJV) cannulation was attempted in 71 (85%) children and femoral vein cannulation in 13 (15%) children. Time to catheter insertion, number of needle passes, and artery puncture were noted. Sixty-one of 63 (97%) children had successful central venous cannulation by an anesthesia fellow using audio-Doppler vein localization. This was significantly greater than the 13 of 21 (62%) successful cannulations among children who had veins localized by ALs. Time to insertion did not differ by method of vein localization; however, the number of needle passes was significantly greater in the AL group. Artery puncture did not differ significantly by method of vein localization.nnnCONCLUSIONnVein localization by audio Doppler significantly increases the rate of successful central venous cannulation and decreases the number of needle passes in pediatric patients when used by inexperienced operators.

Hemodynamic effects of amrinone and colloid administration in children following cardiac surgery

Amrinone was used as the sole vasoactive medication in 9 of 14 children (aged 5 months to 8.25 years) given the drug following open repair of congenital cardiac lesions. Four children received a concomitant dopamine infusion and one infant had the infusion stopped after 5 hours for low mean arterial pressure (49 mmHg). In the 10 children receiving only amrinone, cardiac index increased 21% (range, 0 to 94%) after a total loading dose of 4.5 mg/kg given over 1 hour. Four of 14 patients (29%) required dopamine infusions to maintain mean arterial pressure over 55 mmHg and in these children cardiac index increased from baseline and was maintained during the amrinone infusion. Preload was held constant by administration of whole blood or plasmanate during amrinone loading; a decrease in systemic vascular resistance index was seen resulting in a stable arterial blood pressure. Minimal chronotropic effect was seen and no arrhythmias occurred. The sole child with postoperative pulmonary hypertension had a beneficial decrease in pulmonary artery pressure, increase in cardiac index, and stable systemic blood pressure during amrinone use. Cardiac index changes during amrinone loading in these children were variable and less clearly related to serum levels than reported in adults. Pharmacokinetic analysis in 12 children showed a clearance of 3.4 mL/min/kg, a volume of distribution of 1.65 L/kg, and an elimination half-life of 5.75 hours. Decreases in platelet counts were seen in 6 children and platelet transfusion was needed in 1; thus, serial platelet counts should be monitored.(ABSTRACT TRUNCATED AT 250 WORDS)

Amrinone loading during cardiopulmonary bypass in neonates, infants, and children

OBJECTIVESnTo determine whether amrinone is bound to cardiopulmonary bypass circuits. When amrinone is administered to children during cardiopulmonary bypass, determine whether measured amrinone concentrations differ from those predicted based on a reported volume of distribution of 1.6 L/kg.nnnDESIGNnIn vitro study: Uptake of amrinone by cardiopulmonary bypass circuits was determined. Clinical study: Prospective, open label investigation.nnnSETTINGnUniversity-affiliated tertiary childrens hospital.nnnPARTICIPANTSnClinical study: 27 children participated, including 5 neonates and 9 infants.nnnINTERVENTIONSnIn vitro study: Waste blood was circulated within seven pediatric cardiopulmonary circuits. Amrinone was administered, and blood was serially assayed for amrinone levels. Clinical study: Amrinone (mean dose 4.9 mg/kg) was loaded during cardiopulmonary bypass and amrinone concentrations in pump blood were determined at termination of bypass. Amrinone measured by high-performance liquid chromatography.nnnMEASUREMENTS AND MAIN RESULTSnCardiopulmonary bypass circuit uptake reduced amrinone concentrations to 79% of predicted. After correcting for circuit uptake, serum amrinone levels in patients were significantly higher than predicted. The levels, expressed in the ratio of measured: predicted amrinone concentration, did not differ among neonates, infants, and children older than 1 year of age.nnnCONCLUSIONSnWhen amrinone is administered to children during cardiopulmonary bypass, about 20% of the dose becomes bound to the circuit. Available drug is distributed within a smaller volume than predicted. This may be the consequence of the physiologic perturbations of hypothermic cardiopulmonary bypass.