K. C. Lau
University of Hong Kong
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Featured researches published by K. C. Lau.
Heart | 1986
Maurice P. Leung; C. K. Mok; K. C. Lau; Roxy N S Lo; Cy Yeung
The application of cross sectional echocardiography and pulsed Doppler ultrasound to the management of symptomatic neonates with suspected congenital heart disease was studied in 96 consecutive cases. The ability of echocardiography to establish a complete and accurate diagnosis and a correct management plan was evaluated. Sequential segmental analysis of data from cardiac catheterisation and necropsy identified 536 cardiovascular anomalies. Of the 536 anomalies 512 were correctly diagnosed by echocardiography (sensitivity 95.5%). Seven false positive echocardiographic diagnoses were made (specificity 98.6%). Nearly all the missing diagnoses and all the false positive diagnoses made by echocardiography were extracardiac vascular anomalies. Normal cardiovascular anatomy was at all times correctly identified by echocardiography. In 12 babies (12.5%) a management plan could not be established because of inconclusive echocardiographic findings. Of the 84 proposed plans based on the echocardiographic findings, eight were found to be inappropriate after catheterisation. Thus, 76 babies (79.2%) could have been correctly managed without cardiac catheterisation. The combination of cross sectional echocardiography and pulsed Doppler ultrasound not only allows diagnosis of congenital cardiac anomalies in most neonates but can facilitate appropriate clinical management. Only a minority of neonates with suspected congenital heart disease require cardiac catheterisation and angiography.
Heart | 1986
Maurice P. Leung; C. K. Mok; Roxy N S Lo; K. C. Lau
Twenty nine patients with isolated perimembranous ventricular septal defects were investigated by M mode, cross sectional, and pulsed Doppler echocardiography. Tricuspid valve anomalies were present in all six patients with a left ventricular-right atrial shunt but in only six (26%) of 23 patients who had interventricular shunts only. Systolic flutter of the tricuspid valve was shown in five (83%) of the six patients with a ventriculoatrial shunt but not in the other patients. Systolic turbulence in both the right ventricle and right atrium was detected by Doppler echocardiography only in patients with ventriculoatrial shunting. A perimembranous ventricular septal defect with left ventricular to right atrial shunt can be diagnosed by its combined M mode, cross sectional, and pulsed Doppler echocardiographic features.
International Journal of Cardiology | 1987
Maurice P. Leung; C. K. Mok; P.W. Hui; Roxy N.S. Lo; K. C. Lau; C.K. Li; David L.C. Cheung
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.
Heart | 1987
Roxy N S Lo; K. C. Lau; M Aung-Khin
Aortic atresia with ventriculoarterial discordance in a three day old neonate was studied by cross sectional echocardiography and the anatomy was confirmed at necropsy.
Pediatric Radiology | 1987
Roxy N.S. Lo; M. P. Leung; K. C. Lau
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.
Pediatric Cardiology | 1986
K. C. Lau; M. P. Leung; Roxy N.S. Lo
SummaryIn 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.
Pediatric Radiology | 1989
K. C. Lau; Roxy N.S. Lo; M. P. Leung
Abstract13 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.
Pediatric Cardiology | 1986
M. P. Leung; C. K. Mok; Roxy N.S. Lo; K. C. Lau
SummaryLeft ventricular to right atrial (LV-RA) communications are rare septal defects. The majority of them are congenital in origin and acquired defects are exceedingly rare. The causes of acquired LV-RA communications include chest trauma [3, 4, 7], infective endocarditis [1, 2, 15], and valvar replacement [5, 6, 9, 12–14]. This report describes a case of direct LV-RA and interventricular communications occurring three months after excision of a subaortic shelf.
Chinese Medical Journal | 1989
Lo Ns; Leung Pm; K. C. Lau; Cy Yeung
American Heart Journal | 1990
K. C. Lau; Henry Hing-chuen Cheung; C. K. Mok