Role of amiodarone in the treatment of fetal supraventricular tachyarrhythmias and hydrops fetalis

We report three consecutive hydropic fetuses with fetal tachyarrhythmias treated with amiodarone-two in combination with digoxin and one with digoxin, procainamide, and propranolol. Sinus rhythm was achieved in one case and ventricular rate control was achieved in two cases. All fetuses treated with amiodarone gradually improved. Observed side effects of amiodarone were a maternal rash in one mother and transient neonatal hypothyroidism in one infant. We conclude that amiodarone might be effective and safe for fetal tachyarrhythmias and impending hydrops. The small number of patients suggests that a multicenter cooperative approach is required in order to determine if this is correct.

Intracardiac echocardiography in congenital heart disease: are we ready to begin the fantastic voyage?

Advances in and miniaturization of echocardiographic technology have led to many new methods of examining cardiovascular malformations. Intracardiac echocardiography (ICE) has reached a point where a real impact on clinical medicine can be anticipated. Use of ICE guidance during electrophysiologic and some interventional catheterization procedures will probably become standard clinical practice in the near future. Current results in adults and potential application to and limitations in the pediatric population are discussed.

Usefulness of the myocardial performance index for assessing right ventricular function in congenital heart disease

Quantitative assessment of ventricular function in patients with congenital heart disease is often challenging due to distorted ventricular geometry. A myocardial performance index (MPI) has been reported in adults and children that is a Doppler-derived nongeometric measure of ventricular function. The MPI measures the ratio of isovolumic time intervals (isovolumic contraction time and isovolumic relaxation time) to ventricular ejection time. The effects of altered ventricular preload or afterload on the MPI have yet to be determined. This study assesses the impact of altered preload or afterload on right ventricular (RV) function and the RV MPI in the clinical setting of congenital heart disease. Patient groups were compared with normal pediatric and adult populations before and after repair of their congenital heart lesion. Patients with large atrial septal defects (ASDs) represented the clinical setting of increased ventricular preload, whereas patients with isolated pulmonary valve stenosis represented increased RV afterload. Patients with congenitally corrected transposition of the great arteries (CC-TGA) with severe left atrioventricular valve regurgitation represented a combined increase in RV preload and afterload. The RV MPI in 152 normal children (ages 3 to 18 years) and 37 adults (ages 18 to 51 years) was 0.32 +/- 0.03 and 0.28 +/- 0.04, respectively. In pediatric patients (n = 45) and adult patients (n = 40) with ASD, the RV MPI was 0.35 +/- 0.09 (p = NS) and 0.38 +/- 0.04 (p < 0.01 compared with normal adults), respectively. Patients with pulmonary stenosis (n = 21, ages 1 day to 19 years) had a RV MPI of 0.32 +/- 0.06 (p = NS). CC-TGA patients had a RV MPI of 0.72 +/- 0.17 (p < 0.001). No significant change in the RV MPI was seen in any postoperative patient group despite relief of RV volume or pressure overload. Thus, the MPI is a quantitative measure of RV performance that is appears to be relatively independent of changes in preload or afterload in the clinical setting.

Remote telemedical interpretation of neonatal echocardiograms: impact on clinical management in a primary care setting

OBJECTIVE

The purpose of this study was to evaluate the utility of telemedical echocardiographically assisted neonatal cardiovascular evaluation in a primary care setting.

BACKGROUND

Neonates with congenital heart disease are frequently born far from pediatric subspecialty centers and can be clinically unstable at presentation. Recent advances in telecommunication technology have made it possible to transmit echocardiographic images over long distances. This technology may be beneficial to newborns with heart defects who are born in primary care centers.

METHODS

A retrospective review of all telemedical echocardiograms obtained from neonates (aged 1 day to 30 days) was performed. A telemedical link was created using a T-1 transmission line and a standard voice telephone line between the Mayo Clinic, Rochester, Minnesota (pediatric cardiology site), and the Altru Clinic, Grand Forks, North Dakota (primary care site), which is a general pediatric practice 400 miles from Rochester. Neonates with possible cardiac disorders were identified by the general pediatricians, who then requested telemedical echocardiography.

RESULTS

The 133 neonates had 161 T-1 echocardiograms. Median patient age was two days (range, one day to 29 days). One hundred thirty-two of 133 initial echocardiograms (99%) were obtained because of urgent indications. Transmitted images provided adequate diagnostic information in all patients. Seventy-nine neonates (59%) had a change in medical management or required cardiology follow-up. An immediate change in management occurred in 32 patients (24%), including seven in whom emergency transfer was either arranged or avoided.

CONCLUSIONS

Telemedical echocardiography provides accurate diagnostic data in neonates. Rapid telediagnosis facilitates appropriate care of sick neonates with possible congenital heart disease in the primary care setting. Unnecessary long-distance transfers can be avoided with this technology.

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

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

Late results of bioprosthetic tricuspid valve replacement in Ebstein's anomaly

BACKGROUND

Historically, porcine bioprosthetic valves have poor durability in pediatric patients; nearly half will require replacement within 5 years. However, our early experience with patients having Ebstein's anomaly suggests that tricuspid bioprostheses in this anomaly might have better durability.

METHODS

One hundred fifty-eight patients who received a primary tricuspid bioprosthesis because of tricuspid valve anatomy unsuitable for repair between April 1972 and January 1997 were reviewed. Results were analyzed and Kaplan-Meier curves were constructed to estimate patient survival and probability of remaining free of reoperation.

RESULTS

Follow-up of 149 patients (94.3%) who survived 30 days ranged up to 17.8 years (mean, 4.5 years). Ten-year survival was 92.5%+/-2.5% (SE), 129 late survivors (92.1%) were in New York Heart Association class I or II, and 93.6% were free of anticoagulation. Freedom from bioprosthesis replacement was 97.5%+/-1.9% at 5 years and 80.6%+/-7.6% at 10 and 15 years.

CONCLUSIONS

Bioprosthesis durability in the tricuspid position in patients with Ebstein's anomaly compares very favorably with bioprosthesis durability in other cardiac valve positions, especially for pediatric patients, and also compares favorably with tricuspid bioprosthesis durability in patients with other diagnoses.

Percutaneous echocardiographically guided pericardiocentesis in pediatric patients: evaluation of safety and efficacy

The purpose of this study was to evaluate the safety and efficacy of echocardiographically (echo) guided pericardiocentesis in pediatric patients. Echo-guided pericardiocenteses performed in pediatric patients (age >/=16 years) at the Mayo Clinic between 1980 and 1997 were identified. Presentation, cause and characteristics of the effusion, details of the pericardiocentesis procedure, and outcome were determined by comprehensive chart review supplemented by telephone interviews when necessary. Seventy-three pediatric patients, median age 6.7 years (range 1 day to 16 years), underwent 94 consecutive echo-guided pericardiocenteses for effusions of various causes. Twenty-one (22%) procedures were performed in children younger than 2 years. All but 1 procedure were successful (99%). A mean fluid volume of 237 mL (range 4 to 970 mL) was withdrawn. Only a single attempt was needed for entry into the pericardial space in 87 (93%) procedures. No deaths were associated with the pericardiocentesis procedure. Only 1 major complication occurred (1%), a pneumothorax requiring chest tube reexpansion. Three (3%) minor complications-2 instances of right ventricular puncture and a small pneumothorax-did not require treatment. Extended catheter drainage for a mean of 5.2 +/- 4.5 days (range 1 to 19 days) was used with 30 (32%) of the 94 procedures. For the 52 patients who underwent pericardiocentesis without catheter drainage as the initial management strategy, 18 required 21 repeat pericardiocenteses for recurrence of effusion. In contrast, for the 21 patients who had pericardial catheterization as the initial management strategy, none had recurrences necessitating a repeat procedure (P <.001). Increased utilization of a pericardial catheter was associated with a concomitant decrease in the number of surgical pericardial procedures over the study period. Echo-guided pericardiocentesis was the only therapeutic modality for the management of effusion in 73% of all patients. Echo-guided pericardiocentesis is safe and effective in pediatric patients, including children younger than 2 years. The increasing use of pericardial catheterization in conjunction with this technique was associated with significant reduction of recurrence and decreased frequency of surgical interventions for treatment of pericardial effusion. Echo-guided pericardiocentesis with extended catheter drainage should be considered as primary management strategy for clinically significant pericardial effusions in pediatric patients.

Nongeometric quantitative assessment of right and left ventricular function: myocardial performance index in normal children and patients with Ebstein anomaly

Assessment of ventricular systolic function has been based on the geometric models of ventricular shape. This study was designed to define normal values for a nongeometric myocardial performance index (MPI) in children and to evaluate the utility of MPI in congenital heart disease. The MPI measures the ratio of total time spent in isovolumic activity (isovolumic contraction time and isovolumic relaxation time) to the ejection time. The right ventricular (RV) and left ventricular (LV) MPI were measured in 152 normal children (ages 3 to 18 years) and 45 preoperative patients with Ebstein anomaly (age 1 week to 52 years). In normal children, the RV MPI was 0.32+/-0.03 and the LV MPI was 0.35+/-0.03. In the Ebstein group, both RV and LV MPI were abnormally increased compared with age-matched normal subjects (Ebstein group: RV MPI=0.49+/-0.12, LV MPI=0.42+/-0.09, P < .001). Increasing RV dysfunction was associated with progressively increasing (abnormal) values of RV MPI (P < .001). The myocardial performance index quantitatively reflects ventricular performance in patients with complex ventricular geometry (ie, Ebstein anomaly). In the absence of a geometric solution, this nongeometric index is particularly appealing for the assessment of RV or LV performance.

Outcomes of noncardiac surgical procedures in children and adults with congenital heart disease. Mayo Perioperative Outcomes Group

OBJECTIVE

To assess the outcomes and risk factors for morbidity associated with anesthesia and noncardiac surgical procedures in children and adults with congenital heart disease.

DESIGN

We conducted a retrospective cohort study of the 6-year period from January 1987 through November 1992 at one of the Mayo-affiliated hospitals in Rochester, Minnesota.

MATERIAL AND METHODS

In all children and adults 50 years of age or younger with congenital heart disease who underwent one or more noncardiac surgical or diagnostic procedures and anesthesia, we analyzed the risk factors for 30-day perioperative morbidity and mortality.

RESULTS

The overall frequency of complications among the 276 patients who underwent 480 noncardiac surgical procedures and anesthesia was 5.8% (28 of 480), and only 1 patient died intraoperatively. Major risk factors univariately associated with complications for the first procedures (15 of 276 patients or 5.4%) included the presence of cyanosis (P = 0.002), current treatment for congestive heart failure (P<0.001), poor general health (P<0.001), and younger age at the time of the procedure (P = 0.027). Procedures performed on the respiratory and nervous systems also were associated with high frequencies of complications. Complications in patients undergoing ambulatory surgical procedures were infrequent (1.7%).

CONCLUSION

The frequency of perioperative complications in children and adults who have congenital heart disease and undergo noncardiac surgical procedures and anesthesia is low. Patients who have pulmonary hypertension, congestive heart failure, or cyanosis and children with congenital heart disease who are younger than 2 years of age have an increased frequency of perioperative morbidity.

Diastolic ventricular function in children: a Doppler echocardiographic study establishing normal values and predictors of increased ventricular end-diastolic pressure

OBJECTIVE

To extend noninvasive assessment of diastolic cardiac function into the pediatric age-group.

DESIGN

This study was divided into two phases, the first of which was designed to provide an age-appropriate set of normal diastolic Doppler echocardiographic data for children and adolescents and the second of which was to determine whether these Doppler techniques could be used to identify children with increased ventricular end-diastolic pressure (EDP).

MATERIAL AND METHODS

Complete echocardiographic studies focusing on Doppler variables of diastolic ventricular function were performed on 223 normal children. Values observed were analyzed for dependence on age, heart rate, and gender. Results from the normal group were then compared with Doppler values observed in a group of 24 children with catheterization-substantiated increases in ventricular EDP.

RESULTS

Normal values for the Doppler factors studied vary with both age and heart rate. The variables that most confidently distinguished children with increased EDP from normal subjects were the ratio of and the difference between the durations of pulmonary vein atrial reversal and the mitral A wave. A ratio of 1.2 or more or a difference of 29 ms or more identified those children with increased EDP with sensitivities of 88 and 90% and specificities of 86 and 86%, respectively.

CONCLUSION

Use of the normal data and the Doppler techniques described in this study will allow confident assessment of diastolic function in children as well as in adults.

Partial anomalous pulmonary venous connection: diagnosis by transesophageal echocardiography

OBJECTIVE

This study sought to demonstrate that with proper technique, identification of the normal and abnormal pulmonary venous connection can be made with confidence using transesophageal echocardiography (TEE).

BACKGROUND

Partial anomalous pulmonary venous connection (PAPVC) is an uncommon congenital anomaly whose diagnosis has classically been made using angiography.

METHODS

We performed a retrospective review of all patients of all ages with PAPVC diagnosed at the Mayo Clinic who had undergone TEE because of either right ventricular volume overload or suspected intracardiac shunting by transthoracic echocardiography or intraoperatively.

RESULTS

A total of 66 PAPVCs were detected in 43 patients (1.5/patient); in 2 additional patients, TEE suggested, but did not diagnose, PAPVCs. Shortness of breath was the most common presenting symptom (42.2%), followed by heart murmur and supraventricular tachycardia. Right-sided anomalous veins were identified in 35 patients (81.4%), left-sided in 7 (16.3%) and bilateral in 1 (2.3%). There was a single anomalous connecting vein in 23 patients (53.5%), two in 18 (41.9%), three in 1 (2.3%) and four in 1 (2.3%). The connecting site was the superior vena cava (SVC) in 39 veins (59.1%), right atrial-SVC junction in 6 (9.1%), right atrium in 8 (12.1%), inferior vena cava in 1 (1.5%) and the coronary sinus in 2 (3.0%). Ten anomalous left pulmonary veins were connected by a vertical vein to the innominate vein (15.1%). Sinus venosus atrial septal defect (ASD) was the most common associated anomaly in 22 patients (49%), followed by ostium secundum ASD in 6 and patent foramen ovale in 4. Fifteen patients had an intact atrial septum. Thirty-one patients (68.8%) underwent surgical repair. PAPVC was confirmed in all patients, including the two whose TEE results were suggestive of PAPVC. All 49 PAPVCs detected by TEE preoperatively were confirmed at the time of operation.

CONCLUSIONS

TEE is highly diagnostic for PAPVC and can obviate angiography. Accurate anatomic diagnosis may influence the need for medical and surgical management. TEE should be performed in patients with right ventricular volume overload when the precordial examination is inconclusive.

Improved early morbidity and mortality after Fontan operation: the Mayo Clinic experience, 1987 to 1992

OBJECTIVES

This study sought to evaluate changes in early morbidity and mortality as well as predictors of outcome in our most recent 339 patients undergoing modified Fontan operations.

BACKGROUND

The Fontan operation is the preferred definitive palliation for patients with functional single ventricles. Previously reported early mortality rates after Fontan operation have been substantial.

METHODS

Records of 339 consecutive patients who had a Fontan operation at the Mayo Clinic between 1987 and 1992 (recent cohort) were reviewed. This cohort was compared with the previous 500 patients who had Fontan operations performed between 1973 and 1986 (early cohort).

RESULTS

Recently, overall early mortality after Fontan has decreased significantly compared with that for the early cohort (from 16% to 9%, p = 0.002). This decline occurred despite increased anatomic complexity of patients. Short-term posthospital survival has also improved significantly in recent patients. One-year survival improved to 88% from 79%, and 5-year survival to 81% from 73% (p = 0.006). Patients with common atrioventricular valves and those who took daily preoperative diuretic medication or had either postoperative renal failure or elevated postbypass right atrial pressure were at increased risk for early mortality. Young age was not found to be a risk factor for early mortality. Early mortality for patients with heterotaxia decreased dramatically: recent 30-day mortality was 15% compared with 41% in the early heterotaxy cohort.

CONCLUSIONS

Many factors may have contributed to decreased early mortality after Fontan. Improved patient selection, younger age at time of operation, refinements in surgical techniques and postoperative management may all have had important roles. Proposed technical modifications of the Fontan operation must be evaluated in light of these improved results.

Double-chambered right ventricle: echocardiographic features

Double-chambered right ventricle is an uncommon congenital heart disease, studied mostly by angiography, characterized by the division of the right ventricular cavity into two different pressure chambers. To analyze the anatomic features of this disease, data from 13 patients examined by echocardiography at the Mayo Clinic were reviewed. Despite the anatomic variety of this abnormality, two main types were identified. In the first type, intraventricular obstruction was due to an anomalous muscle bundle crossing the right ventricular cavity from the interventricular septum to the parietal wall. In the second type, no anomalous bundles were identified, and interventricular obstruction was due to marked parietal and septal hypertrophy. The main interventricular gradient was higher in the first type, and a ventricular septal defect was found to be associated more commonly with the second type.

Idiopathic restrictive cardiomyopathy in childhood: diagnostic features and clinical course

OBJECTIVE

To describe the clinical course and outcome of children with idiopathic restrictive cardiomyopathy (IRCM) and to present the Doppler echocardiographic features of this disease in childhood.

DESIGN

We reviewed the Mayo Clinic patient database for the period from 1975 to 1993 to identify children who underwent assessment for IRCM.

MATERIAL AND METHODS

Clinical records and diagnostic studies, including two-dimensional (2-D), M-mode, and Doppler echocardiograms, were reviewed for each patient. Characteristics were analyzed statistically to determine potential predictors of outcome.

RESULTS

Eight children (five girls and three boys) were diagnosed with IRCM between 1975 and 1993 at our institution. The median age at diagnosis was 11 years, and the median duration of follow-up was 11.5 years. Of the eight patients, five died (the median time from initial examination to death was 1 year). All five of these patients had clinical and radiographic evidence of pulmonary venous congestion. In all patients, 2-D and M-mode echocardiography revealed atrial enlargement without ventricular dilatation or hypertrophy. The four patients who underwent detailed diastolic Doppler assessment had findings consistent with restrictive filling and increased left ventricular end-diastolic pressure: (1) short mitral deceleration time, (2) increased pulmonary vein atrial reversal velocity and duration, and (3) pulmonary vein atrial reversal duration greater than mitral A-wave duration.

CONCLUSION

The prognosis for children with IRCM is poor. In this small group of patients, absence of pulmonary venous congestion most consistently predicted extended survival. A combined 2-D and Doppler echocardiographic examination provides a reliable noninvasive means of assessing the physiologic and morphologic features of IRCM in children.

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.

Congenital heart disease: wide-field, three-dimensional, and four-dimensional ultrasound imaging

The next significant advance for cardiovascular ultrasound will be the introduction of clinical three-dimensional (3-D) imaging. With increasing computer power and software and hardware, 3-D ultrasound imaging will become a reality over the next few years. Of all cardiovascular abnormalities, congenital heart disease is one of the most logical entities to lend itself to wide-field and 3-D presentation. Tomographic two-dimensional (2-D) echocardiography has in great part replaced cardiac catheterization as the means of accurately visualizing congenital cardiac defects. However, two distinct limitations exist with current 2-D presentations: (1) limited field of view (ie, 90 degrees sector) and (2) tomographic slices that must be assimilated by the examiner into a 3-D or four-dimensional diagnosis. True 3-D imaging has the ultimate capability of rendering anatomy in a format comparable to looking at the actual cardiac specimen. If electronic rendering were really feasible and of suitable quality, one could envision electronically extracting the heart from a living human and examining abnormalities much as one might examine a cardiac specimen (ie, "electronic vivisection"). This article reviews the state of the art of wide-field and 3-D cardiovascular ultrasound in the assessment of congenital heart disease.

Distinguishing right from left: a standardized technique for fetal echocardiography

Improved echocardiographic equipment and increasing experience have led to accurate and reliable prenatal diagnosis of congenital defects and arrhythmias. However, without a standard convention for acquisition and presentation of fetal images, distinguishing the right side of the fetus from the left side can be difficult and confusing. This article proposes a standard method of image acquisition and presentation that allows confident determination of the fetal right/left axis by easily identified anatomic landmarks. This technique provides a reliable determination of the fetal right/left axis regardless of fetal position (i.e., face up, face down, facing left, or facing right), in both real time and retrospective review. Only after the fetal right/left axis has been determined can accurate diagnoses of fetal atrial and visceral situs, base-apex axis, and cardiac segmental anatomy be made.

Subaortic obstruction in hearts with a univentricular connection to a dominant left ventricle and an anterior subaortic outlet chamber. Results of a staged approach

In 1984 we reported a 56% mortality after major cardiac operations for patients with univentricular connection to a dominant left ventricle, an anterior subaortic outlet chamber, and subaortic obstruction. Since then we have adopted a staged approach to this repair. Between 1984 and 1989 32 patients had such operations. The overall mortality has decreased (16%; p < 0.001). The current cohort was divided by subaortic gradient into three subgroups for comparison with the cohort reported in 1984. Staging improved the outcome in patients with gradients greater than 40 mm Hg (mortality of 17% compared with 67% from 1984; p = 0.05). Patients with gradients from 10 to 25 mm Hg who had a single-stage operation had the best outcome (mortality 6%). Survival has improved. Many factors, including increased awareness of the detrimental effects of subaortic obstruction, improved surgical techniques, better perioperative care, and the appropriate application of a staged repair, have contributed to this improvement. We recommend simultaneous relief of obstruction and a modified Fontan operation for patients with subaortic gradients less than 25 mm Hg. Those with gradients greater than 40 mm Hg should have repair in two stages. It is unclear whether a one-stage or two-stage approach is better for patients with gradients between these extremes.