PubMed Health⌕ Search

Biomedical subjects

W C Yu

Publications and source records attributed to W C Yu.

At least 91 records · Page 5Linked to original sources
PubMed1997

Electrophysiologic characteristics and radiofrequency catheter ablation in patients with clockwise atrial flutter.

INTRODUCTION: Although the mechanism and radiofrequency catheter ablation of counterclockwise (typical) atrial flutter have been studied extensively, information about the electrocardiographic and electrophysiologic characteristics and effects of radiofrequency ablation in patients with clockwise atrial flutter is limited. METHODS AND RESULTS: Thirty consecutive patients with clinically documented paroxysmal clockwise atrial flutter were studied. Endocardial recordings and entrainment study using a "halo" catheter with 10 electrode pairs in the right atrium were performed. Radiofrequency energy was applied to the inferior vena cava-tricuspid annulus (IVC-TA) and/or coronary sinus ostium-tricuspid annulus (CSO-TA) isthmus to evaluate the effects of linear catheter ablation. Eighteen patients had both counterclockwise and clockwise atrial flutters, and 12 patients had only clockwise atrial flutter. Both forms of atrial flutter had similar flutter cycle lengths (232 +/- 30 vs 226 +/- 25 msec, P = 0.526) but reverse activation sequences. Right atrial pacing at a cycle length 20 msec shorter than the flutter cycle length from the CSO-TA isthmus, IVC-TA isthmus, and the area between the two isthmuses revealed concealed entrainment with stimulus-to-P wave intervals of 32 +/- 19, 95 +/- 14, and 50 +/- 17 msec (P = 0.022) in the counterclockwise form, and 110 +/- 12, 40 +/- 20, and 60 +/- 15 msec (P = 0.018) in the clockwise form. In clockwise atrial flutter, 20 patients with biphasic P waves in the inferior leads had the presumed exit site of slow conduction area located at the low posterolateral right atrium; 10 patients with positive P waves in the inferior leads had the presumed exit site located at the mid-high posterolateral right atrium. Among the 18 patients with both forms of atrial flutter, linear ablation lesions directed at the IVC-TA isthmus eliminated both forms of atrial flutter in 14 patients; in the remaining 4 patients, CSO-TA linear lesions eliminated the counterclockwise form and IVC-TA lesions eliminated the clockwise form. Among the 12 patients with the clockwise form only, CSO-TA linear lesions eliminated flutter in 2 and IVC-TA linear lesions eliminated flutter in 10 patients. Successful ablation was confirmed by creation of bidirectional conduction block in the IVC-TA and/or CSO-TA isthmus during pacing from the proximal coronary sinus and right posterolateral atrium sandwiching the linear lesions. During the follow-up period of 17 +/- 8 months, 2 patients had recurrence of clockwise atrial flutter, 1 patient had new onset of atypical atrial flutter, and 2 patients had new onset of atrial fibrillation. CONCLUSIONS: Counterclockwise and clockwise atrial flutters may have overlapping slow conduction areas with different exit sites. Radiofrequency catheter ablation using the linear method directed at the IVC-TA and CSO-TA isthmuses was feasible and effective in treating both forms of atrial flutter.

Adult↗
PubMed1997

Electrophysiologic characteristics and radiofrequency catheter ablation in atrioventricular node reentrant tachycardia with second-degree atrioventricular block.

INTRODUCTION: Detailed electrophysiologic study of AV nodal reentrant tachycardia (AVNRT) with 2:1 AV block has been limited. METHODS AND RESULTS: Six hundred nine consecutive patients with AVNRT underwent electrophysiologic study and radiofrequency catheter ablation of the slow pathway. Twenty-six patients with 2:1 AV block during AVNRT were designated as group I, and those without this particular finding were designated as group II. The major findings of the present study were: (1) group I patients had better anterograde and retrograde AV nodal function, shorter tachycardia cycle length (during tachycardia with 1:1 conduction) (307 +/- 30 vs 360 +/- 58 msec, P < 0.001), and higher incidence of transient bundle branch block during tachycardia (18/26 vs 43/609, P < 0.001) than group II patients; (2) 21 (80.8%) group I patients had alternans of AA intervals during AVNRT with 2:1 AV block. Longer AH intervals (264 +/- 26 vs 253 +/- 27 msec, P = 0.031) were associated with the blocked beats. However, similar HA intervals (51 +/- 12 vs 50 +/- 12 msec, P = 0.363) and similar HV intervals (53 +/- 11 vs 52 +/- 12, P = 0.834) were found in the blocked and conducted beats; (3) ventricular extrastimulation before or during the His-bundle refractory period bundle could convert 2:1 AV block to 1:1 AV conduction. CONCLUSIONS: Fast reentrant circuit, rather than underlying impaired conduction of the distal AV node or infranodal area, might account for second-degree AV block during AVNRT. Slow pathway ablation is safe and effective in patients who have AVNRT with 2:1 AV block.

Aged↗
PubMed1997

Radiofrequency ablation-induced asystole during transaortic approach for a left anterolateral accessory pathway: a Bezold-Jarisch-like phenomenon.

We present a case of cardiac asystole induced by radiofrequency catheter ablation of a left anterolateral accessory pathway in a 28-year-old woman with Wolff-Parkinson-White syndrome who was experiencing recurrent palpitation. Radiofrequency current applied on the ventricular aspect of the mitral annulus corresponding to the aforementioned site provoked profound slowing of the sinus rate preceded by disappearance of the preexcitation, and then asystole ensued. The proposed causal mechanism was a reflexogenically mediated hypotension-bradycardia syndrome (Bezold-Jarisch-like phenomenon) through stimulation of either nearby vagal afferent pathways or sensory terminal receptors at the ablation site.

Adult↗
PubMed1997

Radiofrequency catheter ablation of slow pathway in 760 patients with atrioventricular nodal reentrant tachycardia--long-term results.

BACKGROUND: Although selective radiofrequency catheter ablation of the slow atrioventricular (AV) nodal pathway has provided a curative therapy for patients with AV nodal reentrant tachycardia, information about the long-term result of radiofrequency catheter ablation in patients with different types of AV nodal reentrant tachycardia was not available. This study was to investigate the long-term effect of selective slow pathway ablation in a large group of consecutive patients with AV nodal reentrant tachycardia. METHODS: From December 1990 to June 1996, 760 consecutive patients with clinically documented AV nodal reentrant tachycardia received radiofrequency catheter ablation of antegrade and/or retrograde slow AV nodal pathway at this electrophysiologic laboratory. The data of electrophysiologic characteristics and long-term follow-up were collected. The success rate, complication rate and recurrence rate were analyzed. RESULTS: There were 669 slow-fast form AV nodal reentrant tachycardia, 27 fast-slow form AV nodal reentrant tachycardia, 13 variant form AV nodal reentrant tachycardia, and 51 multiple forms of AV nodal reentrant tachycardia. The electrophysiologic characteristics were different among these four groups. However, radiofrequency catheter ablation attained a 99% success rate in all the four groups with different types of tachycardia. There were 5 accidental injuries to AV conduction. Three of the 5 patients needed implantation of pacemakers. During the follow-up period, there were 14 (1.8%) recurrence of AV nodal reentrant tachycardia. All of the 14 patients had a successful second ablation without recurrence. CONCLUSIONS: This study demonstrated that radiofrequency catheter ablation of slow pathway was a highly effective treatment modality for patients with various types of AV nodal reentrant tachycardia. Furthermore, the incidence of complication rate and recurrence rate were low in an experienced center.

Adolescent↗
PubMed1997

Long-term results of radiofrequency catheter ablation in patients with Wolff-Parkinson-White syndrome.

BACKGROUND: Information about the long-term results of radiofrequency catheter ablation, electrophysiologic characteristics of differently located accessory pathways, and the difference between a single accessory pathway and multiple accessory pathways was limited. METHODS: Nine hundred and thirty-one patients with 1016 accessory pathways (APs) received electrophysiologic study and radiofrequency catheter ablation between July 1, 1989 and June 31, 1996. Group 1 included 856 (91.9%) patients with a single AP and Group 2 included 75 (8.1%) patients with multiple APs. The follow-up period was 48 +/- 37 months (range, 2 to 84 months). RESULTS: Nine hundred and thirteen patients (98.1%) had successful ablation with a complication rate of 1.5%. In Group 1, left free wall pathways were ablated with fewer radiofrequency pulses, shorter procedure time, shorter radiation exposure time and a lower recurrence rate than those at other locations. Comparisons between Group 1 and Group 2 showed that the latter had higher incidences of antidromic tachycardia (3% vs 13%, p < 0.05) and atrial flutter/fibrillation (26% vs 37%, p < 0.05). Regarding radiofrequency catheter ablation, Group 2 needed more radiofrequency pulses (8.7 +/- 7.8 vs 5.5 +/- 7.7, p < 0.001), longer procedure time (3.3 +/- 1.4 vs 2.1 +/- 1.0 hours, p < 0.05) and radiation time (49 +/- 27 vs 29 +/- 19 minutes, p < 0.001), and a higher recurrence rate (10.6% vs 3.3%, p < 0.005) than those in Group 1. Thirty-six patients (4%) with recurrence had more right-side pathways than those without recurrence. In addition, difficult ablation (longer procedure time, longer radiation time and more radiofrequency pulses) was associated with a higher recurrence rate. CONCLUSIONS: These findings demonstrated that a high success rate with a low recurrence and low complication rate of radiofrequency catheter ablation could be achieved in a large population with APs during a long follow-up period.

Adult↗
PubMed1997

Evaluation of preoperative hepatic function in patients with hepatocellular carcinoma undergoing hepatectomy.

BACKGROUND: Postoperative hepatic failure is the leading cause of hospital mortality following hepatectomy for hepatocellular carcinoma (HCC). This prospective study was performed to identify the best test for assessment of the adequacy of hepatic functional reserve in patients with HCC before hepatectomy. METHODS: Between April 1989 and June 1993, 127 patients with HCC underwent hepatectomy. Each patient was evaluated before operation with the indocyanine green (ICG) clearance test, the aminopyrine breath test and the amino acid clearance test. RESULTS: Fourteen patients (11 per cent) died after hepatectomy. ICG retention at 15 min showed significant differences between patients who survived or died. By discriminant analysis, the safety limit of ICG retention at 15 min for major hepatectomy was 14 per cent and the relative risk of hospital mortality was 3. CONCLUSION: The ICG clearance test, expressed as the percentage of ICG retained at 15 min, is the best discriminating preoperative test for evaluating hepatic functional reserve in patients with HCC before hepatectomy.

Adult↗
PubMed1996

Long-term results of radiofrequency catheter ablation in patients with multiple accessory pathways.

Information on the long-term results of radiofrequency catheter ablation in a large group of patients with multiple accessory pathways (APs) was not available. This study included 858 patients with Wolff-Parkinson-White syndrome who underwent electrophysiologic study and radiofrequency catheter ablation: 73 patients (8.5%) had multiple APs. Sixty-six patients had 2 APs, 5 had 3 APs, 1 had 4 APs, and 1 had 5 APs. The most common combination pattern of these pathways were concealed APs (38 patients, 52%). Localization of accessory pathways showed a higher incidence of right free wall (22% vs 11%, p < 0.05), anteroseptal, and midseptal APs (9% vs 5%, p < 0.05) in patients with multiple APs than in patients with 1 AP. The most common anatomic sites for multiple APs were 2 APs in the left wall (21 patients, 28%). Although the success rate was similar (98% vs 99%, p > 0.05), procedure time (3.1 +/- 1.2 vs 2.0 +/- 1.1 hours, p < 0.05) and radiation exposure time (48 +/- 26 vs 29 +/- 19 minutes, p < 0.05) were longer in patients with multiple APs. The recurrence rate was higher in patients with multiple APs (9.5% vs 2.5%, p < 0.05), and the most common site of recurrent APs was in the left free wall (7.2%); in contrast, it was in the right free wall in patients with 1 AP. These findings demonstrated that a high success rate of radiofrequency catheter ablation was found in patients with multiple APs; however, the higher recurrence rate in patients with multiple APs should be considered.

Adult↗
PubMed1996

Temperature and impedance monitoring during radiofrequency catheter ablation of slow AV node pathway in patients with atrioventricular node reentrant tachycardia.

This study was designed to observe the changes of temperature and impedance and to find the role of temperature control in radiofrequency ablation of slow pathways in patients with AV node reentrant tachycardia. Power, impedance and temperature were measured during each application of radiofrequency energy while the generator was operated in the power control mode. A total of 760 applications were delivered in 76 patients. The success rate was 100% without recurrence during a follow-up period of 8 +/- 3 months. The mean catheter tip temperature associated with successful ablation was 51.3 +/- 5.4 degrees C (range 45 degrees C to 64 degrees C), and significantly higher than the unsuccessful pulses (48.7 +/- 6.2 degrees C, P < 0.05). The mean temperature was 49.8 +/- 3.1 degrees C during accelerated junctional rhythm, significantly higher than the pulses without this rhythm. The mean temperature correlated well with early decrease of impedance (r = 0.71, P < 0.001), and an early decrease of impedance more than 5 ohms had an 87% positive predictive value for adequate tissue heating. These data suggested that, if temperature monitoring was available, setting the target temperature at about 51 degrees C could achieve adequate tissue heating for successful ablation of slow pathway; if not, impedance monitoring with an early decrease of impedance < 5 ohms could predict adequate tissue heating.

Catheter Ablation↗
PubMed1996

Dual AV node pathway physiology in patients with Wolff-Parkinson-White syndrome.

Published data on the relationship between dual AV node pathway physiology, locations and numbers of accessory pathways are limited. The purpose of this study is to appraise the dual AV node pathway physiology in a large group of patients with accessory AV pathways. A consecutive series of 759 patients was included for analysis. The incidence of antegrade or retrograde dual AV node pathway physiology and AV node reentrant tachycardia was similar for patients with accessory pathway at different locations. However, the incidence of bidirectional dual AV node pathway physiology (11.1%) and fast-slow type AV node reentrant echo (8.3%) was significantly higher in anteromidseptal accessory pathways. The incidence of antegrade (24.2% vs. 30.8%, P > 0.05), retrograde (4.9% vs. 2.9%, P > 0.05) and bidirectional dual AV node pathway physiology (3.0% vs. 2.9%, P > 0.05) was similar between the patients with a single pathway and multiple accessory pathways. Furthermore, the patients with multiple accessory pathways had a higher incidence of slow-fast form AV node reentrant tachycardia (8.8% vs. 3.0%, P = 0.034) and fast-slow form AV node reentrant echo (8.8% vs. 2.7%, P = 0.02). Thirty-four patients (4.5%) received slow pathway ablation for AV node reentrant tachycardia and none had recurrent tachycardia during the follow up period (26 +/- 7, range 1-56 months). We conclude that it is possible to find dual AV node pathway physiology in patients with accessory pathways because this phenomenon was not rare, especially in patients with a single pathway located in the anteromidseptal area or in patients with multiple accessory pathways.

Adult↗
PubMed1996

Co-existence of atrial tachycardia and common atrial flutter: electrophysiological characteristics and radiofrequency catheter ablation.

Four patients, who had no prior atrial surgery, underwent radiofrequency ablation for clinically documented typical atrial flutter. In addition to typical atrial flutter re-entrant atrial tachycardia was initiated during electrophysiological study in these four patients. We used earliest atrial endocardial activation and concealed entrainment pace mapping with short stimulus-P interval (< 40 ms) to identify the exit site of slow conduction are of atrial flutter were located at the posteromedial right atrium between the coronary ostium and the tricuspid annulus and those of slow conduction area of atrial tachycardia were located at high lateral right atrium in all four patients. Radiofrequency energy applied to these exit sites successfully eliminated both atrial flutter and atrial tachycardia in these four patients. Typical atrial flutter and re-entrant atrial tachycardia with two distinct re-entrant circuits concomitantly occurring in patients without prior atrial surgery are rare. Radiofrequency ablation can abolish both atrial tachyarrhythmias in the same ablation session.

Aged↗
PubMed1996

Electrophysiologic characteristics, electropharmacologic responses and radiofrequency ablation in patients with decremental accessory pathway.

OBJECTIVES: This study sought to characterize the functional properties of decremental accessory atrioventricular (AV) pathways and to investigate their pharmacologic responses. BACKGROUND: Although decremental AV pathways associated with incessant reciprocating tachycardia have been studied extensively, information about the electrophysiologic characteristics and pharmacologic responses of anterograde and retrograde decremental AV pathways is limited. METHODS: Of 759 consecutive patients with accessory pathway-mediated tachyarrhythmia, 74 with decremental AV pathways were investigated (mean age 43 +/- 18 years). After baseline electrophysiologic study, the serial drugs adenosine, verapamil and procainamide were tested during atrial and ventricular pacing. Finally, radiofrequency catheter ablation was performed. RESULTS: Five patients had anterograde decremental conduction over the accessory pathway but had no retrograde conduction. Of the 64 patients with retrograde decremental conduction over the accessory pathway, anterograde conduction over the pathway was absent in 41 (64%), intermittent in 5 (8%) and nondecremental in 18 (28%). In the remaining five patients, anterograde and retrograde decremental conduction over the same pathway was found. The anterograde and retrograde conduction properties and extent of decrement did not differ between anterograde and retrograde decremental pathways. Posteroseptal pathways had the highest incidences of anterograde and retrograde decremental conduction. Intravenous adenosine, procainamide and verapamil caused conduction delay or block, or both, in 10 of 10, 10 of 10 and 4 of 10 of the anterograde and 20 of 20, 20 of 20 and 8 of 20 of the retrograde decremental pathways, respectively. All patients had successful ablation of the decremental pathways without complications. During the follow-up period of 31 +/- 19 months, only one patient experienced recurrence. CONCLUSIONS: Decremental accessory pathways usually had functionally distinct conduction characteristics in the anterograde and retrograde directions. Their pharmacologic responses suggested the heterogeneous mechanisms of decremental conduction.

Adenosine↗
PubMed1996

Induction of apoptosis in epithelial cells by Epstein-Barr virus latent membrane protein 1.

Epstein-Barr virus (EBV) induces human B cell transformation and is closely associated with nasopharyngeal carcinoma. The expression of an EBV latent membrane protein, LMP-1, protects B cells from apoptosis by up-regulating the expression of a cellular oncogene, bcl-2. LMP-1 also transforms rodent fibroblasts and affects the differentiation, morphology and growth of human and rodent epithelial cells. In this report, we describe a novel finding that high level expression of the LMP-1 gene in a human epithelial cell line (RHEK-1) induces apoptosis, characterized by chromosomal DNA fragmentation in the transfected cells. In particular, such an effect was more apparent under serum starvation. We also found that in the transfected RHEK-1 cells, LMP-1 expression neither affected bcl-2 expression nor led the cells to grow in semisolid soft agar medium. These results indicate that LMP-1 may participate in the development of EBV-associated epithelial malignancy via a mechanism different from that seen in B cell or fibroblast transformation.

Apoptosis↗
PubMed1996

Dimension and related anatomical distance of Koch's triangle in patients with atrioventricular nodal reentrant tachycardia.

INTRODUCTION: The dimension of Koch's triangle in patients with AV nodal reentrant tachycardia has not been well described. Understanding the dimension and anatomical distance related to Koch's triangle might be useful in avoiding accidental AV block during ablation of the slow pathway. The purposes of this study were to define the dimension of Koch's triangle and its related anatomical distance and correlate these parameters with the successful ablation sites in patients with AV nodal reentrant tachycardia. METHODS AND RESULTS: We studied 218 patients with AV nodal reentrant tachycardia. The distance between the presumed proximal His-bundle area and the base of the coronary sinus orifice (DHis-OS) measured in the right anterior oblique view was used to define the dimension of Koch's triangle. The distance of the proximal His-bundle recording site from the successful ablation site (DHis-Ab) and the distance as a fraction of the entire length of Koch's triangle (DHis-Ab/DHis-Os) were determined. The mean DHis-Os and DHis-Ab were 25.9 +/- 7.9 and 13.4 +/- 3.8 mm, respectively. DHis-Os negatively correlated with patient age (r = -0.41, P < 0.0001) and body mass index (r = -0.18, P = 0.004). Among the patients with successful ablation sites in the medial area, DHis-Os was longer (27.2 +/- 6.6 vs 24.6 +/- 8.4 mm, P < 0.005), DHis-Ab was similar (12.9 +/- 3.1 vs 13.9 +/- 4.0, P > 0.05) and DHis-Ab/DHis-Os was smaller (0.48 +/- 0.04 vs 0.74 +/- 0.11, P < 0.05). Furthermore, the patients with successful ablation sites in the medial location needed more radiofrequency pulse numbers than those in the posterior location (6 +/- 4 vs 4 +/- 3, P < 0.05). CONCLUSION: The site of successful slow pathway ablation was consistently about 13 mm from the site recording the proximal His-bundle deflection in patients with AV nodal reentrant tachycardia despite marked variability in the dimensions of Koch's triangle; therefore, patients with large triangles required ablation in the medial region rather than the posterior region. Care should be taken when delivering radiofrequency energy to the posteroseptal area in patients with shorter DHis-Os to avoid injury to AV node.

Adolescent↗
PubMed1996

Temperature monitoring in radiofrequency catheter ablation of atrial flutter using the linear ablation technique.

INTRODUCTION: Information about temperature and impedance monitoring during radiofrequency catheter linear ablation of atrial flutter has not been reported. We proposed that a radiofrequency catheter ablation system using a closedloop temperature control model could decrease the incidence of coagulum formation and shorten the radiation exposure and procedure times compared with those found in a power control model. METHODS AND RESULTS: Forty patients (8 women and 32 men; mean age 64 +/- 7 years) with atrial flutter were referred for radiofrequency ablation. The patients were randomized into two groups: group I patients underwent radiofrequency catheter linear ablation of atrial flutter using a power control of energy output model; and group II patients underwent the closedloop temperature control model with a target electrode temperature of 70 degrees C. As compared with group II, group I patients had a higher incidence of coagulum formation (12% vs 2%, P < 0.05), temperature shutdown (11% vs 0%, P < 0.01), and impedance shutdown (16% vs 3%, P < 0.01), more radiofrequency applications (7 +/- 3 vs 4 +/- 2, P < 0.01), and longer procedure time (100 +/- 25 vs 75 +/- 23 minutes, P < 0.05) and radiation exposure time (31 +/- 10 vs 20 +/- 7 minutes, P < 0.05) required for successful ablation. Larger deviations of temperature (9.0 degrees +/- 2.4 degrees C vs 5.0 degrees +/- 1.2 degrees C, P < 0.0001) and impedance (9.2 +/- 2.6 omega vs 5.3 +/- 1.6 omega, P < 0.0001) were also found in group I patients compared with those in group II. CONCLUSIONS: This study demonstrated that a closed-loop temperature control model could facilitate the effects of radiofrequency catheter ablation of the atrial flutter circuit by decreasing coagulum formation, temperature and impedance shutdown, and procedure and radiation exposure times.

Adult↗
PubMed1995

1,25-Dihydroxyvitamin D3 suppresses cell growth, DNA synthesis, and phosphorylation of retinoblastoma protein in a breast cancer cell line.

Cells of a breast adenocarcinoma cell line, CAMA-IEe, were found to contain a moderate concentration of 1,25-dihydroxyvitamin D3[1,25(OH)2D3] receptors. The receptors' dissociation constant calculated by Scatchard analysis was 4.1 x 10(-10) M. These receptors sedimented at around 4.0 S position on a linear 5-20% sucrose density gradient and exhibited an apparent molecular weight of about 46 kDa. Receptor concentration was found to be highest in the early stages of cell growth, decreased continuously when cells were actively growing, and reached the lowest level at confluence. Suppression of cell growth, of DNA synthesis, and of the phosphorylation of retinoblastoma protein by 1,25(OH)2D3 at concentrations about 10(-7) M were observed. Treatment with 10(-7) M 1,25(OH)2D3 for 12 hr or longer caused elevation of cytosolic free calcium in CAMA-IEe cells. These results show that CAMA-IEe cell growth is suppressed by 1,25(OH)2D3 and that the suppression is possibly mediated through calcium mobilization.

Adenocarcinoma↗
PubMed1995

Prospective double-blind placebo-controlled randomized trial on the use of ranitidine in preventing postoperative gastroduodenal complications in high-risk neurosurgical patients.

To determine the efficacy of ranitidine in preventing clinically acute overt gastroduodenal (GD) complications (bleeding and/or perforation) after neurosurgery, 101 patients with nontraumatic cerebral disease considered at high risk of developing postoperative GD complications were randomized in a standard double-blind manner to receive either ranitidine (50 mg every 6 hours) or placebo medication preoperatively. Postoperative serial GD endoscopy was used to document the occurrence of complications: an overt symptomatic complication was defined as bleeding requiring blood transfusion and/or surgery. Fifty-two patients received ranitidine and 49 received a placebo preoperatively; 30 developed overt GD bleeding; nine of these received ranitidine and 21 received a placebo. Ranitidine significantly reduced the incidence of bleeding (p < 0.05). Multivariate logistic regression analysis revealed three factors of independent significance in predicting overt GD bleeding: use of a placebo drug, a gastric pH of less than 4, and a high daily volume of gastric output. The authors conclude that ranitidine is useful in preventing postoperative GD complications in high-risk neurosurgical patients.

Adolescent↗