A national network for the tele-education of Canadian residents in pediatric cardiology.

A trial of 11 video-conferenced teaching sessions for residents in pediatric cardiology was performed by the 7 training programs in Canada in order to share expertise in specialized areas, to expose trainees to educational telemedicine, and to acquaint residents with other programs and personnel. Topics included cardiac pathology, arrhythmias, magnetic resonance imaging, fetal physiology, pulmonary hypertension, and cardiomyopathy. The sessions were evaluated by 93 residents by questionnaire for content and technology. Session content was highly rated. Videoconference picture quality was highly rated, but sound quality and visual aids were rated as neutral or unsatisfactory by a significant minority, related to problems with several early sessions, subsequently corrected. 60% of respondents rated the videoconferences as good as live presentations. Presenters were generally satisfied although they required some adjustments to videoconferencing. The average cost per session was $700 Canadian. Videoconferencing of resident educational sessions was generally well accepted by most presenters and residents, and the trial has formed the basis for a national network. Adequate organizational time, and careful attention to audiovisual needs, are most important. Videoconference guidelines are suggested for presenters based on this experience.

Intra-utero diagnosis of anomalous right ventricular muscle bundles in association with a ventricular septal defect: a case report.

The morphology and natural history of anomalous right ventricular muscle bundles (ARVMB) have been described in a number of postnatal studies. Whether this is a congenital or acquired cardiac lesion remains obscure. A fetal echocardiogram performed in a 32-week gestation mother showed a large ventricular septal defect and anomalous right ventricular muscle bundles, which were easily appreciated at the ostium-infundibular level. The diagnosis was confirmed postnatally and at 6 months of age the child underwent surgical repair. This report documents the presence of ARVMB in a fetus, at a time when hemodynamics cannot explain the development of right ventricular muscle bundles. It suggests that at least, the morphologic substrate for this disease is congenital.

Echocardiographic follow-up of atrial septal defect after catheter closure by double-umbrella device.

BACKGROUND: Transcatheter device occlusion of atrial septal defects is an attractive approach, but its efficacy and place in patient management remain to be determined. METHODS AND RESULTS: To evaluate the medium-term results of atrial septal defect device occlusion and factors influencing residual shunting, transesophageal and transthoracic echocardiograms of 49 patients were reviewed. Transesophageal echocardiograms on 48 patients immediately following surgical closure revealed residual shunting in 2% compared with 91% after device occlusion; this proportion decreased to 53% after a mean follow-up of 10 months. The actuarial analysis suggests a progressive resolution of shunting with time. One patient had residual shunting by transesophageal echocardiography immediately after surgical closure compared with 29 after a mean follow-up of 10 months after device occlusion. Residual shunting was not influenced by (1) dimension, location, or position with relation to the device as assessed by transesophageal echocardiography; (2) location of the defect; or (3) device size relative to the stretched dimension of the defect. In 15 patients, a poor correlation existed between transesophageal and transthoracic echocardiographic findings. Variability in serial transthoracic echocardiographic findings was observed in 14. Right ventricular dimension, heart size, and presence of a murmur at follow-up did not correlate with the presence or size of residual shunting after device occlusion. CONCLUSIONS: These results suggest that ongoing spontaneous resolution of residual shunting occurs after device insertion. Factors related to the defect or device could not predict eventual resolution of residual shunting. Transthoracic echocardiography in the follow-up of these patients may not be reliable in determining presence of residual shunting.

Ambulatory blood pressure monitoring and left ventricular mass and function after successful surgical repair of coarctation of the aorta.

Late cardiovascular morbidity and mortality remain significant despite apparently successful surgical repair of aortic coarctation. Alterations in cardiac function have been reported in normotensive patients who have had successful repair, the reasons for which remain unclear. This study addresses the relation between ambulatory blood pressure measurements and alterations in left ventricular performance in 20 patients with normotension at rest after successful repair of aortic coarctation. Exercise testing, ambulatory blood pressure monitoring and two-dimensional echocardiographic studies in 13 boys and 7 girls (mean age 14.2 +/- 2.31 and 14.7 +/- 3 years, respectively) who had no evidence of recoarctation were compared with the findings in 20 matched control subjects. No difference was found in systolic blood pressure at rest or peak exercise between patients and control subjects. Male patients developed a significant arm/leg gradient at peak exercise. Systolic ambulatory blood pressure was higher throughout the day in the male group. In the female group, systolic blood pressure was higher only during sleep. No difference was found in diastolic blood pressure or heart rate. The transverse aortic arch was smaller and the left ventricular mass greater in all patients. The relation of wall stress to rate-corrected velocity of shortening was 2 SD above normal in 8 of the 20 patients, suggesting that some have enhanced contractility. The E/A ratio on the atrial echocardiogram was significantly reduced in the patient group. Successfully treated patients who are normotensive at rest after operation are still at risk for developing end organ damage, which is probably explained by incipient mild hypertension documented by ambulatory blood pressure monitoring.

Transcatheter occlusion of the persistently patent ductus arteriosus. Forty-month follow-up and prevalence of residual shunting.

BACKGROUND: Percutaneous closure of the persistently patent ductus arteriosus with the Rashkind prosthesis is an established effective therapeutic modality, although some patients are left with residual shunting. To evaluate this, a retrospective study of the prevalence of persistent shunting over a 40-month period in the first 190 patients was undertaken. METHODS AND RESULTS: All patients (male 45, female 145; mean age, 3.9 +/- 3.6 years; range, 5 months to 20 years) had serial clinical and color-flow echocardiographic follow-up at 6-12-month intervals (range, 6-40 months). Four patients required surgical removal of an embolized device, leaving a cohort of 186 patients in whom 196 procedures were performed, resulting in successful placement of 195 devices (43 17-mm [22%] and 152 12-mm [78%]). Complications occurred in seven of 195 procedures (3.6%). Nine of 10 attempted reocclusions (all with 12-mm devices) were successful. The prevalence of residual shunting was 38% at 1 year, 18% at 2 years, and 8% at 40 months. Patients with ductus measuring less than 4 mm had a higher success of initial occlusion. Thirty-four patients were left with residual shunting determined by color-flow Doppler study, but no anatomic or echocardiographic features were found predictive for residual shunting. All remain asymptomatic with 26 (76%) having no detectable murmur, two (6%) a continuous murmur, and six (18%) a systolic murmur. CONCLUSIONS: Catheter occlusion will obviate the need for surgery in the majority of patients presenting with persistently patent ductus arteriosus. Reocclusion has been found feasible in those with continuous murmurs (nine of nine) and should be offered early because it is unlikely for spontaneous closure to occur in this group. It appears prudent to follow those with small residual shunting because further spontaneous closure can occur.

Natural history of cardiac rhabdomyoma in infancy and childhood.

Although spontaneous regression of cardiac rhabdomyoma has been reported, prognosis is still considered to be poor and surgery continues to be indicated. The experience with rhabdomyoma diagnosed in live infants over a 20-year period was reviewed. Diagnosis by angiography or echocardiography was accepted only if multiple tumors were present or if tuberous sclerosis was also diagnosed. Nine patients (3 diagnosed prenatally and the remaining 6 at age less than 8 months) were identified as having a total of 24 tumors. Measurements in 2 planes demonstrated at least some evidence of regression in 24 patients (100%), with 20 of 24 having complete resolution. One patient required delayed surgery for excision of a subaortic ridge that appeared at the site of a resolved tumor. Our findings suggest that pediatric cardiac rhabdomyoma is most often a benign condition in which spontaneous regression is the rule. Surgery is recommended only for patients with refractory dysrhythmias or severe hemodynamic compromise.

Catheter occlusion of the persistently patent ductus arteriosus.

Catheter occlusion of a persistently patent ductus arteriosus was attempted in 40 patients (11 men and 29 women, mean age 7.2 +/- 8.3 years, range 244 days to 40 years), using a transvenously placed Rashkind umbrella occluder (USCI). Thirty-one 12-mm and six 17-mm diameter devices were successfully placed in the ductus (internal diameter average 3.9 mm, range 2 to 9 mm). One procedure was abandoned when fluoroscopy failed to visualize the device. There were 2 immediate embolizations subjected to surgical recovery. A residual shunt was present on the immediate postocclusion ventriculogram in 12 of 37 procedures (32%). Twenty-eight patients (75%) have had at least a follow-up at 3 months with Doppler study and 6 (21%) continued to have shunting into the pulmonary artery. Three of 4 patients have undergone successful placement of a second device and 1 patient's shunting spontaneously resolved at 1 year postimplant, leaving only 2 patients (7%) with persistent shunts. There has been 1 episode of probable prosthetic endarteritis and 1 patient has developed mild narrowing of the left pulmonary artery related to device placement. Catheter occlusion of the patent ductus arteriosus using the Rashkind umbrella appears to be a safe and effective method of non-surgical management.

Critical aortic stenosis. Survival and management.

The factors associated with survival in 40 neonates (age less than 28 days) with critical aortic stenosis undergoing either open (22 patients) or closed (18 patients) transventricular aortic valvotomy were reviewed. Significant adverse correlates with survival included evidence of poor perfusion preoperatively (low pH, greater than Grade 2/6 soft ejection systolic murmur) and marked congestive heart failure (hepatomegaly, cardiomegaly, elevated left atrial pressure). Congenital mitral stenosis (anulus less than 11 mm), a small aortic anulus (less than 6.5 mm), and failure to achieve an adequate aortic orifice (greater than 6 mm), at operation were identified as factors associated with increased mortality. Initial perioperative survival was better with closed aortic valvotomy. However, there was no significant difference in overall operative survival between closed (9/18, 50%) and open (8/22, 36%) aortic valvotomy (p = 0.26). The incidence of early reoperation (less than 1 year of age) was greater in perioperative survivors undergoing closed valvotomy (7/13, 54%) rather than open valvotomy (1/10, 10%) (p less than 0.05). In conclusion, long-term survival among patients with critical neonatal aortic valve stenosis remains disturbingly low (13/40, 32%) and has not significantly improved over the past 20 years.