C. K. Mok

Risk Factors for Development of Acute Renal Failure (ARF) Requiring Dialysis in Patients Undergoing Cardiac Surgery

Acute renal failure (ARF) is one of the major complications after cardiopulmonary bypass for open heart operations. The present study was undertaken to identify the risk factors for the development of ARF following cardiopulmonary bypass (CPB). Four hundred and forty-seven consecutive patients who underwent open heart procedures from July 1994 to June 1995 were analyzed retrospectively. Their mean age was 55.6 ± 14.2 (SD) years (range, 18 to 80). Dialysis was instituted whenever a patient exhibited inadequate urine output ( <0.5 mL/kg/hr) for 2 to 3 hours despite correction of hemodynamic status and diuretic therapy, especially if fluid overload, hyperkalemia, or metabolic acidosis were also present. Twenty variables were analyzed by univariate analysis; these included nine preoperative variables—age, sex, hypertension, atherosclerosis, diabetes mellitus, left ventricular end-diastolic dimension (LVEDD) >5 cm, preoperative congestive heart failure, renal insufficiency (serum creatinine ≥130 μmol/L on two occasions), and sepsis—10 intraoperative variables—duration of CPB, redo procedures, emergency surgery, use of intraaortic balloon pump (IABP) in operating room, use of gentamicin, use of ceftriaxone, use of sulbactam/ampicillin, requirement of deep hypothermic circulatory arrest, duration of low mean perfusion pressure (mean pressure < 50 mmHg for more than 30 minutes), operation on multiple valves—and one postoperative variable— significant hypotension (systolic blood pressure less than 90 mmHg for more than 1 hour). Significant variables or the variables having a trend (p < 0.1 ) to be associated with ARF were included in stepwise multiple logistic regression analyses. Three regression analyses were performed separately. The incidence of ARF requiring dialysis in the study period was 15.0%. Significant risk factors for whole group of patients (regression I) were preoperative renal insufficiency (p < 0.0001 ), postoperative hypotension (p < 0.0001 ), cardiopulmonary bypass time more than 140 min (p<0.005), preoperative congestive heart failure (p<0.01),and history of diabetes mellitus (p<0.01).The risk factors in the valve group of patients (regression II) were preoperative renal insufficiency (p<0.0001) and postoperative hypotension (p<0.05).Risk factors in the CABG patients (regression III) were postoperative hypotension (p=0.0001), CPB time more than 140 min (p<0.05), preoperative renal insufficiency (p<0.05),and age (p<0.05).The authors conclude that preoperative renal insufficiency and postoperative hypotension are the most important independent risk factors for ARF in postcardiac surgical patients. In addition, CPB time greater than 140 minutes and old age are also independent risk factors for ARF in CABG patients. CPB time more than 140 minutes, history of diabetes mellitus, and preoperative congestive heart failure are independent risk factors for development of ARF in our total group of patients. These findings may have important clinical implications in the preven tion of ARF in postcardiac surgical patients.

Repair of ruptured sinus of valsalva aneurysm: Determinants of long-term survival

BACKGROUND Ruptured sinus of Valsalva aneurysm is a rare cardiac anomaly and long-term survival after surgical treatment is not well established. This study was designed to investigate the determinants of long-term survival after repair of ruptured sinus of Valsalva aneurysm. METHODS From April 1978 to April 1996, 53 patients underwent operation for ruptured sinus of Valsalva aneurysm. The incidence among our cardiac surgical population was 0.56%. Long-term survival was investigated in 46 patients (13 to 65 years) who survived the operation, with 96.2% follow-up completeness (mean+/-standard deviation, 6.5+/-4.9 years; maximum, 17.2 years), by univariate and multivariate analyses. RESULTS There was no early operative death and no recurrence after the initial repair. Actuarial survival was 83.8%+/-8.4% at 15 years. Reoperation, aneurysm draining into the left ventricle, aortic prosthetic dehiscence, bacterial endocarditis, and aortic cross-clamp time (<70 minutes) were significant factors in long-term survival (p < 0.05). Multivariate analysis revealed that only aortic prosthesis dehiscence was the significant factor influencing late survival (p = 0.0001). CONCLUSIONS Surgical treatment for ruptured sinus of Valsalva aneurysm is safe and has satisfactory results. Aortic prosthesis dehiscence is the independent determinant for long-term survival. Other factors including bacterial endocarditis, concomitant ventricular septal defect repair, and aortic valve replacement did not independently influence long-term survival.

The role of cross sectional echocardiography and pulsed Doppler ultrasound in the management of neonates in whom congenital heart disease is suspected. A prospective study.

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.

Intraoperative TEE Assessment of Ventricular Septal Defect With Aortic Regurgitation

BACKGROUND It is desirable to repair but not replace the aortic valve in patients with ventricular septal defect and acquired aortic regurgitation. Precise definition of the valvar pathology with monitoring of its repair perioperatively would enhance the surgical management of this condition. METHODS Fourteen consecutive patients (age, 10.6 +/- 6 years; weight 29.7 +/- 5.7 kg) who underwent repair of ventricular septal defect with aortic regurgitation were studied by intraoperative transesophageal echocardiography. The severity of prolapse of each of the individual aortic cusps and its adjacent sinus was assessed and the valvar regurgitation quantified by Doppler-derived regurgitant indices. The echocardiographic and surgical findings were correlated and the preoperative and postoperative echocardiographic data were compared to assess the effectiveness of operation. RESULTS Eight subarterial and six perimembranous defects were located accurately and their sizes (11.8 +/- 3.0 mm) correlated well (r = 0.80) with the surgical measurements. Transesophageal echocardiography detected prolapse of the aortic valve and its sinus in all 14 patients. The severity of the prolapse was severe in 10, moderate in 4, and mild in 5 leaflets. One the basis of these findings, together with the Doppler-derived mean regurgitant indices, exploration of the valve and valvuloplasty were executed appropriately in 12 of 14 patients. In all 14 patients, transesophageal echocardiography after bypass revealed no further cuspal prolapse and significant reduction of the mean regurgitant index (0.55 +/- 0.23 to 0.17 +/- 0.15, p < 0.0001). Residual ventricular septal defect was detected in 5 patients and the only patient with significant shunting who required reexploration was identified correctly. CONCLUSIONS Intraoperative transesophageal echocardiography can assess effectively the surgical repair of ventricular septal defect with aortic regurgitation and provide information that directs and alters surgical plans to the benefit of patients.

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.

An echocardiographic study of perimembranous ventricular septal defect with left ventricular to right atrial shunting

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.

Paediatric thymoma: Unusual occurrence in two siblings

Invasive cystic thymoma is reported in two siblings (an 11-year-old girl and a 9-year-old boy) and the radiographic, CT and ultrasonographic features are described. The tumours were removed by thoracotomy. Familial thymic masses are reviewed, and the imaging differential diagnosis of cystic anterior mediastinal mass in a child is discussed.

Left subclavian afterioesophageal fistula induced by a foreign body

A left subclavian arterioesophageal fistula was diagnosed in a 35-year-old man at exploratory thoracotomy for suspected aortoesophageal fistula. After successful closure of the arterial fistula the patient developed a mediastinal abscess and esophagopleural fistula. The latter was successfully managed by retrosternal jejunal esophagoplasty followed by excision of the thoracic esophagus. This report documents a case of left subclavian arterioesophageal fistula and illustrates the importance of early diagnosis and surgical intervention of arterial perforation secondary to a foreign body in the esophagus.

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.

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)