Perioperative myocardial ischemia: importance of the preoperative ischemic pattern

Previous studies investigating the incidence of myocardial ischemia in patients undergoing coronary-artery bypass grafting (CABG) surgery have not considered the potential significance of the preoperative ischemic pattern in the development of intra- and postoperative myocardial ischemia and infarction. Accordingly, the authors compared the frequency and severity of pre-, intra-, and postoperative ischemic episodes (ST-segment depression greater than or equal to 0.1 mV or elevation greater than or equal to 0.2 mV) in 50 men with severe coronary artery disease scheduled for elective CABG. All subjects were monitored by continuous electrocardiography (ECG) (Holter monitor) for 2 preoperative days, intraoperatively, and 2 postoperative days (total monitoring time = 4,363 h). Routine anti-anginal medications were continued until the morning of surgery, and the anesthetic management of the patient was not controlled. During the preoperative period, 42% of the patients had ECG ischemic episodes, 87% of which were clinically silent. Only 18% developed intraoperative ischemia. Postoperatively, the incidence increased to 40%. The number of ischemic episodes/hour (epis/h) of monitoring among the three monitoring periods was similar (0.09 +/- 0.12 epis/h preoperatively, 0.11 +/- 0.20 epis/h intraoperatively, and 0.05 +/- 0.08 epis/h postoperatively; P = NS). The median duration of ischemic episodes was similar pre- and intraoperatively (16 vs. 18.5 min, P = NS), but greater postoperatively (41 min, P less than 0.05). Seventy-six per cent of the perioperative ECG ischemia occurred without acute change (+/- 20% of control) in blood pressure or heart rate.(ABSTRACT TRUNCATED AT 250 WORDS)     

Postoperative myocardial ischemia in patients undergoing coronary artery bypass graft surgery. S.P.I. Research Group

Cardiac morbidity and mortality after coronary artery bypass graft (CABG) surgery continue to be significant problems. To determine the prevalence, characteristics, and prognostic importance of postoperative myocardial ischemia after CABG surgery, the authors monitored 50 patients continuously for 10 perioperative days with the use of two-lead electrocardiography (ECG). ECG changes consistent with ischemia were defined as a reversible ST depression of 1 mm or greater or an elevation of 2 mm or greater from baseline, lasting at least 1 min. Baseline was adjusted for positional changes and temporal drift. All episodes were verified, with the use of the ECG monitor printout (ECG complexes), by two independent blinded investigators. Clinical care was not controlled by study protocol, and clinicians were unaware of the research data collected. Twenty-six of 50 patients (52%) had 207 episodes of perioperative ischemia (3,409 ischemic minutes). Postoperatively, ischemia developed in 48% of patients, compared with 12% preoperatively and 10% intraoperatively before bypass. Postoperative ischemia was most common in the early period (postoperative days [PODs] 0-2; 38% of patients), peaking during the first 2 h after revascularization, and less common during the late postoperative period (PODs 3-7; 24% of patients). Almost all (120 of 122; 98%) postoperative episodes (after tracheal extubation) were asymptomatic: only 9 of 70 (13%) early episodes were detected by clinical ECG monitoring. Postoperative ischemia did not appear to be related to acute changes in myocardial oxygen demand: only 39% of the postoperative episodes were preceded by a greater than 20% increase in heart rate. However, tachycardia persisted throughout the postoperative week (22-33% of all heart rates greater than 100 beats per min), and patients with postoperative ischemia (POD 0) more frequently had tachycardia (median 43% vs. 12% of the time; P less than 0.01). Five adverse cardiac outcomes occurred on the day of surgery; all five were preceded by postoperative ischemia, three by intraoperative ischemia before bypass, and none by preoperative ischemia. Patients with late postoperative ischemia did not have an adverse cardiac outcome. The authors conclude the following: 1) ischemia is more prevalent postoperatively than preoperatively or intraoperatively before bypass; 2) the incidence of postoperative ischemia peaks shortly after revascularization, during which time it is symptomatically silent, difficult to detect, and related to adverse cardiac outcome; 3) late postoperative ischemia also is silent, but it is less prevalent and not associated with in-hospital adverse cardiac outcome; and 4) a relationship between ischemia and persistently elevated postoperative heart rate may exist and warrants additional investigation.     

Electrocardiographic changes during and after isoflurane-induced hypotension for neurovascular surgery

We evaluated the effects of isoflurane anaesthesia and induced hypotension in 33 neurosurgical patients by electrocardiographic monitoring and serial cardiac enzyme measurements. An electrocardiogram (ECG) and serum enzymes were obtained preoperatively, intraoperatively and postoperatively in the recovery room and for three consecutive days. ECG leads II, V1 and V5 were monitored continuously during anaesthesia. Patients who had had a subarachnoid haemorrhage and a high incidence of abnormal preoperative ECG (42 per cent). Ten patients developed ECG changes intraoperatively, but these changes were unrelated to isoflurane-induced hypotension. Fifty-three per cent of patients developed an abnormal postoperative ECG. These abnormalities consisted mostly of nonspecific ST segment or T wave changes. At no time was there an elevation in cardiac enzyme activity. We found that nonspecific ECG changes are relatively common in patients undergoing vascular neurosurgical procedures. There was no enzymatic evidence of myocardial infarction and we can only speculate that these ECG changes are related to intracranial surgical manipulation.     

Thoracic epidural anesthesia does not influence the occurrence of postoperative sustained atrial fibrillation

BACKGROUND: To evaluate whether thoracic epidural anesthesia (TEA) can reduce the incidence of atrial fibrillation (AF) after coronary artery bypass grafting (CABG). METHODS: Forty-one patients undergoing CABG were treated with TEA intraoperatively and postoperatively. Another 80 patients served as the control group. The sympathetic and parasympathetic activities were evaluated by analysis of neuropeptides, catecholamines and heart rate variability (HRV), preoperatively and postoperatively. RESULTS: Postoperative AF occurred in 31.7% of the TEA-treated patients and in 36.3% of the untreated patients (p = 0.77). TEA significantly suppressed sympathetic activity, as indicated by a less pronounced increase of norepinephrine and epinephrine (p = 0.03, p = 0.02) and a significant decrease of neuropeptide Y (p = 0.01) postoperatively in TEA-treated patients compared to untreated patients. The HRV variable expressing sympathetic activity was significantly lower and the postoperative increase in heart rate was significantly less in the TEA group than in the control group after surgery (p = 0.01, p < 0.001). Among patients developing AF, the maximal number of supraventricular premature beats per minute increased significantly in untreated patients postoperatively but remained unchanged in TEA-treated patients (p = 0.004 versus p = 0.86). CONCLUSIONS: TEA has no effect on the incidence of postoperative sustained AF, despite a significant reduction in sympathetic activity.     

Tachyarrhythmias and triggering factors for atrial fibrillation after coronary artery bypass operations

BACKGROUND: We evaluated the role of supraventricular arrhythmias and assessed clinical predictors of atrial fibrillation (AF) that developed after coronary artery bypass operations. METHODS: Eighty patients, with a mean age of 65.8 years, underwent 24-hour Holter monitoring preoperatively and for 4 consecutive days postoperatively, or until clinically documented AF, for analysis of the number of premature beats and tachyarrhythmias. Atrial areas and atrial peptides were measured preoperatively and postoperatively. RESULTS: Twenty-nine of 80 (36.3%) patients had postoperative AF. Preoperatively, the maximal supraventricular premature beats per minute were higher in the AF group (p = 0.02). The body mass index and total amount of cardioplegia were lower (p = 0.02 and p = 0.006, respectively), and withdrawal of beta-blockers postoperatively more frequent (p = 0.001) in the AF group, but atrial areas and atrial peptides did not differ. CONCLUSIONS: Frequent supraventricular premature beats preoperatively may indicate a propensity for AF. A larger amount of cardioplegia during the cross-clamp period may reduce the risk of postoperative AF. Further studies are mandatory to clarify why patients with lower body mass index were more prone to AF.     

Perioperative Ventricular Arrhythmias in Patients Undergoing Partial Left Ventriculectomy

BACKGROUND: Although incidence of ventricular arrhythmias after partial left ventriculectomy (PLV) has been reported, there are no studies comparing incidence before and after PLV. Although operative scars may give rise to arrhythmias, improved energetic efficiency after PLV may decrease their incidence. METHODS: Pre- and postoperative ventricular arrhythmias were monitored by Holter ECG and analyzed in 17 patients undergoing PLV in Curitiba, Brazil. RESULTS: Although total 24-hour heart beat (THB) increased significantly (p = 0.018), ventricular premature contractions (VPCs) decreased markedly (p = 0.036), excluding one patient dying in low cardiac output (LOS) who had terminal arrhythmias increased multifold. In the remaining 16 patients, VPC pairs were also reduced significantly on the average (p = 0.038). In contrast, ventricular tachycardia (VT; more than three consecutive VPCs) disappeared in five patients, decreased in two patients, and newly occurred in four patients, with five patients showing no change; one of them developed a prolonged VT, successfully reversed by external cardioversion. CONCLUSIONS: Despite notable significant increase in THB immediately after PLV, PVC and PVC pairs were significantly decreased in contrast to VT, which disappeared in some patients and newly occurred in other patients, remaining constant on the average. Sustained VT occurring in a patient with all other arrhythmias suppressed may suggest a unique electrophysiological substrate, may justify prophylactic use of amiodarone or an implantable cardioverter-defibrillator, and may underscore the importance of further and extended studies.     

Perioperative monitoring of the electrocardiogram during cerebral aneurysm surgery

Electrocardiographic (ECG) abnormalities occur frequently following a subarachnoid hemorrhage and may also occur intraoperatively and postoperatively in patients undergoing neurovascular procedures. The aim of this study was to assess the relationship between ECG changes and the neurological status of the patient, the size and the location of the aneurysm, and the influence of these changes on the cardiac and neurological outcome. The preoperative ECG was analyzed in 270 patients. Forty-five patients had intraoperative Holter monitoring. An immediate postoperative ECG was recorded in 120 patients and 60 patients had three consecutive postoperative ECGs. Preoperatively, 52% of the patients had an abnormal ECG and the incidence was highest in patients with a poorer neurological status. Most of the ECG changes involved the T wave or the ST segment. Intraoperative and postoperative changes occurred in 35 and 65% of the patients, respectively, and were independent of the studied factors. There were no documented cardiac events. The presence of an abnormal preoperative ECG did not influence the neurological outcome of the patient, but fluctuating postoperative changes were associated with a worse outcome.     

New onset arrhythmias after the extracardiac conduit Fontan operation compared with the intraatrial lateral tunnel procedure: early and midterm results

Background

Arrhythmias are one of the main causes of postoperative morbidity superseding Fontan operations. Comparative data on the incidence of sinus node dysfunction after the extracardiac Fontan operation (ECFO) and the intraatrial lateral tunnel Fontan operation (LTFO) are very limited and controversial. The aim of this study was to evaluate whether ECFO decreases the risk of postoperative arrhythmias compared with LTFO.

Methods

Seventy-four consecutive patients received either an LTFO (n = 29, 5 recordings in 1992 to 9 recordings in 1997) or an ECFO (n = 45, 11 recordings in 1995 to 5 recordings in 2001). The rhythm was documented preoperatively and postoperatively with standard electrocardiogram (ECG) recording and ECG monitoring. During follow-up all patients had 2-8 (median 3) standard ECG recordings per year. Additionally 45 patients (65%) had a Holter ECG at least once a year.

Results

Median follow-up post-ECFO was 4.4 years (1.6-7.2) and post-LTFO it was 7.9 years (5.4-11.1). There were 5 early deaths (3 LTFO, 2 ECFO) and 1 late death (LTFO) (total mortality 8%). Sinus rhythm persisted in 37 ECFO patients (86%) as compared with 13 LTFO patients (50%) (p < 0.001). The incidence of new onset supraventricular tachyarrhythmias (SVTs) post-ECFO compared with LTFO was lower: 5 patients (11%) versus 11 patients (38%) early postoperatively (p < 0.001) and none versus 7 patients (27%) during follow-up (p < 0.001), respectively. Early postoperatively 10 LTFO patients (34%) and another 3 patients during follow-up required permanent pacemaker implantation due to bradyarrhythmias, but none of the ECFO patients required this.

Conclusions

Our data suggest that ECFO decreases the incidence of postoperative new onset arrhythmias during early and midterm follow-up compared with LTFO.     

Technetium stannous pyrophosphate myocardial scintigrams in the recognition of myocardial infarction in patients undergoing coronary artery revascularization.

Myocardial imaging using technetium 99m stannous pyrophosphate (99mTc-PYP) has been utilized preoperatively and three to five days postoperatively to detect myocardial infarction in 48 patients undergoing aortocoronary bypass grafting, including 7 having valve replacement (5 aortic, 2 mitral) in addition to revascularization. In the total group of patients operated on there were 3 deaths (6%). Preoperatively, 26 patients had unstable angina and 10 had severe left main coronary artery disease. Eleven of the 48 (23%) were women. ECG and enzyme-proved infarctions occurred in 6 of the 48 patients (12%), but the addition of 99mTc-PYP myocardial imaging demonstrated scintigraphic evidence of infarction in 15 patients (31%), including 2 who died in the operating room. The 99mTc-PYP myocardial imaging technique, which has proved safe, simple, and relatively inexpensive in these patients, suggests that the incidence of infarction after coronary bypass operations is somewhat higher than has been previously recognized from just ECG and enzyme changes. This technique also has been of value in helping to exclude myocardial infarction in difficult clinical situations such as postoperative arrhythmias and the postpericardiotomy syndrome.     

Perioperative myocardial ischemia in patients undergoing elective hip arthroplasty during lumbar regional anesthesia.

Perioperative myocardial ischemia predicts unfavorable outcomes and occurs in as many as 41% of patients with coronary artery disease or cardiac risk factors undergoing noncardiac surgery. To determine the prevalence of myocardial ischemia, we studied 52 consecutive unselected patients undergoing elective hip arthroplasty during lumbar regional anesthesia. Patients were continuously monitored for 6 days using a three-channel Holter monitor. Ninety-nine episodes of myocardial ischemia occurred in 16 patients (31%), six of whom were considered preoperatively to be at low risk for coronary artery disease. Forty-four percent of the ischemic episodes were preceded or accompanied by a heart rate greater than or equal to 100/min and 56% by a heart rate greater than or equal to 90 beats/min. Ninety-six percent of the ischemic episodes were clinically silent, and 82% were not related to patient care events. Thirteen episodes of myocardial ischemia occurred preoperatively, 1 intraoperatively, and 85 postoperatively. The incidence of postoperative ischemic episodes showed a circadian variation: 44% occurred between 6 AM and noon, 33% between noon and 6 PM, 17% between 6 PM and midnight, and 6% between midnight and 6 AM. Six adverse cardiac events occurred during hospitalization (three of the six among patients with perioperative ischemia) and an additional four events during a follow-up period of 12 months (all four events occurred among patients with perioperative ischemia). Patients with perioperative myocardial ischemia had a relative risk of 2.6 (95% confidence interval 1.3-5.2) to develop an adverse cardiac event postoperatively.     

Atrial activity during cardioplegia and postoperative arrhythmias

Cardioplegia provides excellent protection for the left ventricle, but the right atrium may be poorly protected. Myocardial temperatures, right atrial electrical activity, and postoperative arrhythmias were assessed in 103 patients participating in two consecutive randomized trials comparing blood cardioplegia (n = 36), crystalloid cardioplegia (n = 38), and diltiazem crystalloid cardioplegia (n = 29). Both right atrial and right ventricular temperatures were significantly warmer (p less than 0.05) during delivery of the blood cardioplegic solution than during delivery of either the crystalloid or the diltiazem crystalloid cardioplegic solutions; the aortic root temperatures were 9 degrees +/- 2 degrees C with blood cardioplegia and 5 degrees + 1 degrees C with both crystalloid and diltiazem crystalloid cardioplegia. Atrial activity during cardioplegic arrest was greatest with blood cardioplegia (12 +/- 3 beats/min), lower with crystalloid cardioplegia (10 +/- 2 beats/min), and minimal with diltiazem crystalloid cardioplegia (5 +/- 1 beats/min, p less than 0.05). Perioperative ischemic injury (by creatine kinase MB isoenzyme analysis) was greatest with crystalloid cardioplegia (p less than 0.05). Postoperative supraventricular arrhythmias (both treated and untreated) were more frequent after crystalloid cardioplegia (crystalloid, 63%; blood, 40%; diltiazem, 47%; p less than 0.05). Patients in whom supraventricular arrhythmias developed had significantly more postoperative ischemic injury (by creatinine kinase MB isoenzyme analysis, p less than 0.05). Blood cardioplegia reduced supraventricular arrhythmias by reducing ischemic injury despite warmer intraoperative temperatures and more right atrial activity. Diltiazem crystalloid cardioplegia reduced postoperative arrhythmias by improving intraoperative myocardial protection and suppressing intraoperative and postoperative atrial activity. Crystalloid cardioplegia cooled but did not arrest the right atrium intraoperatively, resulted in the most perioperative ischemic injury, and yielded the highest incidence of postoperative supraventricular arrhythmias.     

Effect of pre-treatment with intravenous atropine or glycopyrrolate on cardiac arrhythmias during halothane anaesthesia for adenoidectomy in children

We studied the effect of anticholinergics on the incidence of cardiac arrhythmias during paediatric anaesthesia. ASA I-II children (n = 77) undergoing adenoidectomy were randomly allocated to three groups. Intravenous atropine 0.02 mg kg-1 was given in group A (n = 25), glycopyrrolate 0.004 mg kg-1 in group G (n = 27) and physiological saline in group P (n = 25) 3 min before the induction of anaesthesia. The children breathed spontaneously under halothane anaesthesia with 66% nitrous oxide in oxygen after induction with thiopentone and succinylcholine. Perioperative monitoring of the ECG (Holter recordings) and oxygen saturation was carried out. Ventricular tachycardia occurred in 16.0%, 18.5% and 12.0% of the children in groups A, G and P respectively (ns). The incidence of ventricular arrhythmias (ventricular tachycardia, ventricular bigeminy, ventricular premature beats > 10) was 20.0% in group A, 44.4% in group G and 36.0% in group P (ns). Bradycardia (< 70 beats min-1) was observed in 0.0%, 14.8% and 24.0% of patients in groups A, G and P respectively (A vs P, P < 0.05). The use of anticholinergics did not influence the incidence of ventricular arrhythmias during halothane anaesthesia in children. Bradycardia was more common in the placebo group than in the atropine group.      

Arrhythmias during spinal anesthesia for Cesarean section

PURPOSE: Spinal block has long been considered a safe anesthesia technique for surgery. However, severe bradycardia, cardiac arrest, and other arrhythmias during spinal anesthesia have been reported and the incidence of intraoperative arrhythmias is not well established. In this study the incidence of arrhythmias during spinal anesthesia was determined. METHODS: We studied 254 healthy women undergoing Cesarean section under spinal anesthesia prospectively. Spinal anesthesia with 10 mg bupivacaine mixed with 0.2 mg morphine was performed at the L3-4 interspace. Intraoperative arrhythmias were recorded and verified later by a cardiologist. RESULTS: First degree atrioventricular block developed in nine patients (3.5%), second degree atrioventricular block in nine (3.5%), severe bradycardia (heart rate < 50 beats x min(-1)) in seventeen (6.7%), multiple VPC in three (1.2%). The height and weight of patients with severe bradycardia, multiple VPCs, or atrioventricular block were not different from those of the other patients. However, the age of patients in the potentially dangerous arrhythmias group was greater than that in the other group (P = 0.006). CONCLUSION: The incidence of arrhythmias as well as hypotension during spinal anesthesia for Cesarean section was higher than expected. Although most of these arrhythmias were transient and recovered spontaneously, they might unexpectedly occur and sometimes need immediate and prompt treatment. It is necessary to remain vigilant during spinal anesthesia for Cesarean section and careful monitoring of these patients is warranted, especially in older parturients.     

Diagnosis of perioperative myocardial infarction after coronary artery bypass.

The diagnosis of perioperative myocardial infarction (POMI) in patients undergoing coronary artery bypass is uncertain because the criteria of infarction are unclear. Fifty patients who underwent coronary artery bypass were evaluated preoperatively and postoperatively with serial ECGs, creatine phosphokinase (CPK), isoenzyme determinations, and technetium pyrophosphate myocardial scans. Clinical evaluation correlated with exercise testing and postoperative angiography supported the diagnosis in questionable cases. Thirty-five patients (70%) had no evidence of POMI by any criteria, and 2 patients (4%) had unequivocal evidence of infarction by all criteria. Our studies indicate the complexities of diagnosing POMI. We believe that the serially recorded ECG is the most useful diagnostic technique. CPK isoenzyme determinations may be useful but are difficult to interpret in the operative setting. Preoperative cardiac scans are necessary so as to avoid a high incidence of false-positive scans postoperatively. In doubtful cases, postoperative coronary arteriography and left ventricular angiography may provide the most definitive information.     

Microvascular Transplantation of Adipose Tissue and Serum Level of Adipocyte Products

Microvascular transplantation of subcutaneous adipose tissue is an essential step in reconstructive surgery after breast carcinoma. Serum levels of adipose tissue products may serve as indicators for transplant function. This study aimed to determine serum leptin and tumor necrosis factor (TNF)-alpha plasma levels pre-, intra-, and postoperatively in 20 patients undergoing reconstructive breast surgery and in 7 women undergoing abdominoplasty operation. In the patients undergoing reconstructive breast surgery, the serum leptin levels decreased intraoperatively from 14.5 +/- 13.1 to 9.1 +/- 7.3 ng/ml, a decrease of 63%. An increase in serum leptin levels to 13.5 +/- 12.7 ng/ml (93% of the initial value) was found on postoperative day 1. This was paralleled by similar changes in the plasma levels of TNF-alpha (preoperatively, 20 +/- 7.3 pg/ml; intraoperatively, 17 +/- 11.4 pg/ml; postoperatively, 21 +/- 10.8 pg/ml). In the patients undergoing abdominoplasty, plasma leptin and TNF-alpha levels decreased intraoperatively (20% and 27%, respectively) and postoperatively (44% and 27%, respectively). The results of our pilot study indicate that a postoperative increase in the level of serum leptin after reconstructive breast surgery may be related to successful transplant function.     

Combined cardioplegia delivery offers no advantage over antegradecardioplegia administration in coronary surgical patients with a preserved left ventricular function

The effects of antegrade and of combined antegrade and retrograde cardioplegia were compared in 101 patients undergoing elective coronary artery surgery. The patients were randomly allocated to two groups. antegrade cardioplegia was administered in 53 patients and combined cardioplegia in 43 patients. The patients of the two groups were similar in age, sex and left ventricular ejection fraction. Aortic clamping time and the number of coronary bypasses were equal in the groups. The ventricular septal temperature was measured continuously during cardioplegia administration, after each distal anastomosis accomplished, and continuously after aortic declamping. Serum CK-MB activities were serially measured for up to 3 days postoperatively. Electrocardiograms (ECG) were taken preoperatively, as well as on the first, second and eighth postoperative days. The left ventricular function was evaluated with a volume load test preoperatively and on the first postoperative morning. The two groups were similar with respect to myocardial cooling, response to volume loading, the number of patients with perioperative myocardial infarctions, cardiac arrhythmias or atrioventricular conduction blocks and clinical outcome. However, the CK-MB activities were lower in the antegrade group suggesting better myocardial protection in an unselected group of patients undergoing coronary artery bypass grafting.     

Plasma magnesium in patients submitted to cardiac surgery and its influence on perioperative morbidity

BACKGROUND: To determine the changes in magnesaemia in cardiac surgical patients submitted to cardiopulmonary bypass (CPB) and their influence on perioperative morbidity. METHODS: Setting: the cardiovascular surgery department of a university hospital. Patients: 60 patients of both sexes, mean age 60+/-12 yrs, operated on consecutively for myocardial revascularization or valve replacement. Interventions: plasma Mg2+ levels were measured preoperatively, during CPB, postCPB and throughout the first 24 hrs after operation. Preoperative plasma Mg2+ levels of these patients were compared with those of 15 non-cardiac surgical patients and 11 healthy volunteers. RESULTS: Mean values of Mg2+ similar in the three populations although in the group of cardiac patients the number of hypomagnesaemic patients was significantly higher (16 patients=26.6%). In these 16 patients, preoperative hypomagnesaemia had a statistically significant relationship with the preoperative treatment with beta-blockers and previous history of arrhythmias (p<0.05). A progressive statistically significant decrease of Mg2+ was observed throughout the surgery that remained low at 24 hours postoperatively (p<0.05). Normomagnesemic patients needed significantly more shocks and electrical energy to obtain heart defibrillation after CPB. The incidence of both postoperative arrhythmias and postoperative low cardiac index (<2.5 L.m2) was statistically significantly more frequent in hypomagnesaemic patients (p<0.05). CONCLUSIONS: Preoperative hypomagnesaemia was more frequent in this small sample of cardiac surgical patients than in non-cardiac surgical patients and was related to preoperative treatment with b-blockers. Hypomagne-saemia caused by CPB persisted 24 hrs after operation and was associated with higher incidence of both postoperative arrhythmias and low cardiac index.     

Postoperative delirium following gastrointestinal surgery in elderly patients

Postoperative delirium is a common complication which can interfere with the surgical treatment and recovery of elderly patients, and is likely to prolong their hospitalization. Unfortunately, there is as yet no completely effective pre- and/or post operative technique of patient care to reduce or prevent postoperative delirium. In this study, 36 patients aged over 70 years undergoing gastrointestinal operations were assessed to examine the relationships between the preoperative cognitive state, the postoperative sleep cycle, and the occurrence of postoperative delirium. All patients were evaluated preoperatively using the revised version of Hasegawa's dementia scale (HDS-R). We correlated those test results and assessed the sleep-wakefulness disturbance postoperatively, to obtain a clinical DMS-III diagnosis of postoperative delirium. The incidence of postoperative delirium was 17% (6/36). The patients who developed postoperative delirium demonstrated preoperative cognitive impairment, and had a short sleep period during the night and a long sleep period during the day. Postoperatively, these results suggest that HDS-R is a useful method of evaluating preoperative cognition in elderly patients. Considering that sleep deficiency is likely to predispose elderly patients to postoperative delirium, techniques to prevent sleep deprivation may be of considerable value in minimizing the incidence of postoperative delirium.     

Analysis of stone disease in morbidly obese patients undergoing gastric bypass surgery

BACKGROUND AND PURPOSE: Recent studies have demonstrated a higher incidence of nephrolithiasis in the morbidly obese. Nephrolithiasis also has been described as a potential outcome after gastric bypass surgery. This is the first study to our knowledge that examines the incidence of nephrolithiasis in the morbidly obese in the setting of gastric bypass surgery at a tertiary referral center. PATIENTS AND METHODS: We retrospectively reviewed the records of patients undergoing laparoscopic gastric Roux-en-Y bypass surgery for morbid obesity at our institution for the incidence of nephrolithiasis preoperatively, de novo stones postoperatively, and both preoperative and postoperative stone formation. RESULTS: Of the 972 patients who underwent a laparoscopic gastric bypass for the treatment of morbid obesity between 1990 and the present, 85 (8.8%) were found to have upper urinary-tract calculi preoperatively, and 32 (3.2%) had de novo stones postoperatively. Of those 85 who had stones preoperatively, 26 (31.4%) developed recurrent stones postoperatively. CONCLUSIONS: These results support findings in the current literature that nephrolithiasis has a higher incidence in the morbidly obese population. The combination of preoperative stone history and gastric bypass surgery may place patients at a higher risk of future stone formation. This latter group of patients should be screened for postoperative stone formation.     

The preoperative prevalence and postoperative incidence of thromboembolism in patients with hip fractures treated with dextran prophylaxis.

A prospective preoperative and postoperative venographic study of hip fracture patients has documented a significant preoperative prevalence and postoperative incidence of thromboembolic disease. A statistically higher incidence of deep-venous thrombosis is observed in patients with femoral neck fractures compared to patients with intertrochanteric fractures. A 9% (15 of 176) preoperative prevalence and an 11% (12 of 108) incidence of new postoperative thromboembolic disease were detected. There was a predilection for deep-venous thrombosis in the injured extremity compared to the noninjured extremity both preoperatively and postoperatively.