PubMed Health⌕ Search

Biomedical subjects

R N Lo

Publications and source records attributed to R N Lo.

At least 19 recordsLinked to original sources

Management evolution of pulmonary atresia and intact ventricular septum.

To examine the impact on survival and clinical course of incorporating the morphologic classification of the right ventricle into the evolving management strategy for babies with pulmonary atresia and intact ventricular septum, the surgical results and follow-up status of the first 62 consecutive patients managed in this hospital between 1979 and 1990 were reviewed. Before 1984, all 23 babies from group I underwent primary right ventricular outflow reconstruction irrespective of right ventricular morphology and size. Since 1984, depending on the morphology and size of the right ventricle, 39 babies from group II had either closed transventricular pulmonary valvotomy (n = 31) or a shunt operation (n = 8). There were 10 hospital (43%) and 2 late deaths (total mortality 52%) in our group I patients. Three of the 11 long-term survivors had cyanosis at rest but none had any residual pressure gradient across the pulmonary outflow. Group II had 6 hospital (15%) and 4 late deaths (total mortality = 26%). Of the 29 long-term survivors, 9 had a second-stage right ventricular outflow reconstruction, 8 had balloon valvuloplasty and 2 had successful Fontan operation. At the latest follow-up, 5 children from this group have cyanosis at rest, 1 has a residual gradient (55 mm Hg) across the infundibulum, and 3 have right ventricular dysfunction. The hospital and total mortality for babies in group II was significantly lower than that in group I (p < 0.01). These data suggest that tailoring the treatment to the right ventricular anatomy results in a lower overall mortality although long term postoperative hemodynamic abnormalities are observed in both groups.

Abnormalities, Multiple↗

Modified Fontan procedure for severe Ebstein's malformation with predominant tricuspid stenosis.

Two children, aged 7 and 6 years, had severe Ebstein's malformation of the tricuspid valve and underwent operation because of progressive cyanosis (saturation, 70%). Preoperative angiography demonstrated linear attachment of the distal edges of the displaced anterosuperior and mural leaflets, leaving only a "keyhole" communication between the atrialized and functional portions of the right ventricle. Operation was directed toward completely excising these dysplastic leaflets, which were obstructing the flow of blood. The continuity between the functional right ventricle and pulmonary trunk was left intact. In addition, an atriopulmonary truncal connection was established. Postoperatively, both children were in functional class I with arterial saturation of 95%. Angiography and Doppler echocardiography demonstrated that there was a dominant phase of systolic flow of blood up the pulmonary trunk from the right ventricle, and also diastolic filling of the pulmonary arteries through the atriopulmonary truncal connection. The filling patterns did not change over time for the follow-up period of 4 and 1.5 years, respectively. This modified Fontan procedure appears to be an effective surgical alternative for some patients with severe Ebstein's malformation and predominant tricuspid stenosis.

Child↗

Balloon valvuloplasty after pulmonary valvotomy for babies with pulmonary atresia and intact ventricular septum.

During a 2 1/2-year period, staged procedures of transventricular closed pulmonary valvotomy followed by balloon valvuloplasty were attempted in 12 babies with pulmonary atresia and an intact ventricular septum. All babies immediately underwent valvotomy when echocardiography revealed a tripartite right ventricle with adequate inflow and outflow dimensions and without sinusoidal-coronary arterial fistulas. After valvotomy, the overall mortality rate was 25% (3/12), but the only surgical death (1/12, 8%) was due to failure to establish continuity between the right ventricular cavity and the pulmonary trunk. The other 2 babies died of neonatal complications after successful valvotomy. Angiocardiography performed 5 to 18 months after valvotomy documented substantial growth of the right ventricular inflow and outflow dimensions in the 9 survivors. Twelve balloon dilation procedures were then performed in 7 babies. All except 1 achieved a significant drop in the right ventricular to left ventricular peak systolic pressure ratio (0.96 +/- 0.40 to 0.56 +/- 0.28; p less than 0.01). Balloon valvuloplasty was not required in 1 baby and failed in the other, who then underwent successful right ventricular outflow tract reconstruction. After these staged procedures, follow-up at 1 month to 20 months (mean follow-up, 14.8 months) revealed resting cyanosis in 3 babies, which was related to severe residual infundibular stenosis (55 mm Hg) in 1 and a subnormal tricuspid valve annulus in 2. The remaining 5 babies (including 1 who required no valvuloplasty) were active and pink (saturation greater than 97%) and had a mean Doppler estimated gradient of 19 mm Hg (range, 8 to 36 mm Hg) across the pulmonary valve.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Catheterization↗

Abnormal renal and splanchnic arterial Doppler pattern in premature babies with symptomatic patent ductus arteriosus.

The flow velocity pattern in the descending aorta, renal arteries, and celiac and superior mesenteric arteries was studied with pulsed Doppler in eight premature babies with symptomatic ductus arteriosus before and after ductal closure, as compared to nine premature babies without ductus arteriosus. There was a decrease or reversal of flow in diastole in the above arteries in babies with ductus and diastolic flow reappeared after ductal closure. This diastolic steal phenomenon has not been previously demonstrated in the abdominal arteries. It may contribute to proneness to ischemic damage of abdominal organs in premature babies.

Aorta, Thoracic↗

Axillary artery counter-current aortography in the newborn with aortic arch obstruction.

13 newborn infants with aortic coarctation were evaluated by counter-current aortographic technique. The right radial or brachial artery approach (2 cases in each group) did not give successful aortic arch imaging while the right axillary artery approach resulted in adequate imaging in each of 9 cases investigated. In 2, the axillary artery was transiently weakened but returned to normal within 24 h. No other complications were encountered. Axillary artery counter-current aortography is a safe and relatively non-invasive procedure which can be used to image the aortic arch in the newborn babies when other non-invasive diagnosis of aortic arch obstruction is tentative.

Aortic Coarctation↗

The management of symptomatic neonates with suspected congenital heart disease using combined cross-sectional echocardiography and pulsed Doppler flow study as the definitive investigations.

We studied prospectively 140 consecutive symptomatic neonates with suspected congenital heart disease by combined cross-sectional and pulsed Doppler echocardiography. Using the sequential segmental approach, the anatomy at all cardiovascular junctions was clearly defined in 89 (64%) babies. Based on the non-invasive investigations, 47 went to surgery while 42 babies were treated medically. The other 51 babies underwent further cardiac catheterisation. Of these, only 23 (16%) required diagnostic catheterisation prior to their management decision. The remaining 28 babies were catheterised for (1) angiographic measurement of anatomical structures (n = 12), (2) haemodynamic measurement (n = 1), and (3) balloon atrial septostomy (n = 15). One hundred and two babies had ultimate verification of their echocardiographic diagnoses. A total of 612 cardiovascular segments were identified. There were 33 (5%) echocardiographic errors, 23 of missed or uncertain diagnosis and 10 wrong interpretations. The diagnostic sensitivity and specificity for the combined non-invasive technique were thus 96 and 98%, respectively. Only one death was attributed directly to an echocardiographic error. Hence when the clinical outcome was taken into consideration, 88 of the 89 neonates without an initial catheterisation were judged to be appropriately managed for their presentation.

Echocardiography↗

Pompe's disease presenting as supraventricular tachycardia.

A Chinese infant with Pompe's disease (type II glycogenosis) had an unusual presentation of supraventricular tachycardia. The patient subsequently died of ventricular fibrillation. The clinical presentation and the mechanism of the arrhythmia are discussed.

Glycogen Storage Disease Type II↗

Renal blood flow pattern by noninvasive Doppler ultrasound in normal children and acute renal failure patients.

A pilot study of the Doppler renal arterial flow pattern was done in a group of 38 normal children, including 11 neonates age 2 weeks or less, 10 infants age 2 weeks to 1 year, and 17 children age 1 year and over. The appearance time, acceleration time, end-diastolic to peak-systolic velocity ratio (d/S), and diastolic to systolic flow ratio (A2/A1) increased with age. Another four patients with acute renal failure showed a characteristic absence of blood flow in the whole or late-diastolic phase. Diastolic flow reappeared with recovery. Doppler renal arterial flow pattern may be a noninvasive investigation of diagnostic and prognostic value.

Acute Kidney Injury↗

Balloon atrial septostomy under two-dimensional echocardiographic control.

Balloon atrial septostomy was performed under two-dimensional echocardiographic control in 18 consecutive neonates. Initially, a subcostal long-axis view was used to guide the catheter into the right atrium. Then, by tilting the transducer medially, a plane traversing the inferior vena caval-right atrial junction, foramen ovale, and left atrium was obtained to direct the manipulation of the catheter into the left atrium and monitor the septostomy procedure. As the catheter was always in view, catheter manipulation was easy and complications were avoided.

Cardiac Catheterization↗

Demonstration of ascending aorta in hypoplastic left heart syndrome with aortic atresia by balloon occlusion aortography.

Balloon occlusion angiography in the descending aorta produced clear retrograde visualization of the hypoplastic ascending aorta and related structures in eighteen neonates with aortic atresia. Transient bradycardia was the only complication observed. It is technically simpler than retrograde cannulation of the aorta via an arteriotomy and should be the method of choice when cardiac catheterization is required in patients with the hypoplastic left heart syndrome.

Aorta↗

Cross-sectional and pulsed Doppler echocardiography of the atrioventricular junction of hearts with univentricular atrioventricular connexion.

The atrioventricular junction of 52 consecutive patients with univentricular atrioventricular connexion was examined by cross-sectional and pulsed Doppler echocardiography. The echocardiographic features were then compared with catheterisation and cineangiographic findings. In the diagnosis of the mode of atrioventricular connexion, cross-sectional echocardiography was superior to cineangiography in differentiating single inlet with absence of one atrioventricular connexion from double inlet with a common atrioventricular valve. Straddling atrioventricular valves were diagnosed by echocardiography alone. Using pulsed Doppler echocardiography, the diagnostic sensitivity of atrioventricular valvar regurgitation was 92.6% and the specificity 100%. By mapping the regurgitant jet with pulsed Doppler echocardiography, an index was derived to evaluate the severity of atrioventricular valvar regurgitation. The indices obtained correlated well with cineangiographic grading on a three-point scale (Spearman rank correlation coefficient: rs = 0.9). Thus, cross-sectional echocardiography coupled with a range-gated Doppler system provide accurate anatomical details of the atrioventricular junction and reliable assessment of atrioventricular valvar regurgitation in patients with univentricular atrioventricular connexion.

Adolescent↗

Aortic atresia with complete transposition.

Aortic atresia with ventriculoarterial discordance in a three day old neonate was studied by cross sectional echocardiography and the anatomy was confirmed at necropsy.

Abnormalities, Multiple↗

Retrograde transfemoral catheterization of the left ventricle in children with aortic valve stenosis.

In 19 consecutive children with aortic valve stenosis, the left ventricle was entered retrogradely with a Gensini catheter guided by a tip-deflector guidewire which could produce any desirable degree of curvature at its tip. In all patients, the aortic valve was retrogradely traversed for measurement of the pressure gradient (mean gradient = 53 mmHg, mean valve area = 0.36 cm2), and left ventriculography. No complications were encountered. This technique is safe, simple, and effective in retrograde catheterization of the left ventricle in children with aortic stenosis.

Adolescent↗