Characterization of Surgical Movements As a Training Tool for Improving Efficiency

INTRODUCTION

Surgical experience is often reflected by efficient, fluid, and well-calculated movements. For a new trainee, learning these characteristics is possible only by observation as there is no quantification system to define these factors. We analyzed surgeons' hand movements with different experience levels to characterize their movements according to experience.

METHODS

Hand motions were recorded by an inertial measurement unit (IMU) mounted on the hands of the surgeons during a simulated surgical procedure. IMU data provided acceleration and Eulerian angles: yaw, roll, and pitch corresponding to hand motions as radial/ulnar deviation, pronation/supination, and extension/flexion, respectively. These variables were graphically depicted and compared between three surgeons.

RESULTS

Participants were assigned to three groups based on years of surgical experience: group 1: >15 y; group 2: 3-10 y; and group 3: 0-1 y. Visualization of the roll motion, being the main motion during suturing, showed the clear difference in fluidity and regularity of the movements between the groups, showing minimal wasted movements for group 1. The angle of the roll motion, measured at the minimum, midpoint, and maximum points was significantly different between the groups. As expected, the experienced group completed the procedure first; however, the acceleration was not different between the groups.

CONCLUSIONS

Surgeons' hand movements can be easily characterized and quantified by an IMU device for automatic assessment of surgical skills. These characteristics graphically visualize a surgeon's regularity, fluidity, economy, and efficiency. The characteristics of an experienced surgeon can serve as a training model and as a reference tool for trainees.

Localization of coronary bypass targets in hard-to-see coronary arteries

BACKGROUND

Precise identification of coronary arteries and selection of anastomotic sites are critical stages of coronary bypass surgery. Visualization of coronary arteries is occasionally challenging when the heart is covered with a thick layer of fat or scar tissue. In this paper, we review the methods to localize the coronary arteries during coronary surgery.

METHODS

Prior publications were searched to summarize all available methods for localization of coronary arteries during coronary surgery.

RESULTS

Five clinically recognized and three experimental techniques from the literature review are reviewed and summarized.

CONCLUSIONS

Knowledge of various techniques of coronary artery identification in hard-to-see coronary arteries is an important asset in coronary surgery and especially useful during the most critical option of the most common heart surgery.

A Universal Device to Convert a Continuous Flow Assist Device to a Pulsatile Flow Device to Simulate Normal Blood Flow and Pressure Patterns

BACKGROUND

Continuous follow assist devices (CFAD) are the most commonly used mechanical circulatory support devices. Compared to Pulsatile flow assist devices (PFAD), CFADs deliver a non-physiologic type of flow, which might contribute to complications related to lack of pulsatility in these devices. Moreover, lack of pulsatility complicates the clinical management of these patients who often present with good perfusion but with no palpable pulse and none or a negligible pulse pressure on blood pressure measurement.

METHODS AND RESULTS

Presented here is a concept of a universal converter device that can be added inline other CFADs to convert the flow from continuous to pulsatile, simulating a normal flow and pressure pattern. After initial implantation and stabilization with a CFAD, adding this converter might potentially provide the benefits of pulsatile physiologic flow. The device is made of 2 components connected in parallel, working in tandem in user determined cycles. The continuous flow through a specifically positioned openings create a smooth conversion to a pulsatile flow. This device can convert a continuous flow to a physiologic pulsatile flow to achieve a native-like flow pattern and potentially prevent some CFAD complications.

CONCLUSION

This paper presents the concept of pulsatility generation and simulation for other assist devices. Such a device can be a universal add-on or a supplemental option for CFADs.

Effect of Blood Flow on Cardiac Morphogenesis and Formation of Congenital Heart Defects

Congenital heart disease (CHD) affects about 1 in 100 newborns and its causes are multifactorial. In the embryo, blood flow within the heart and vasculature is essential for proper heart development, with abnormal blood flow leading to CHD. Here, we discuss how blood flow (hemodynamics) affects heart development from embryonic to fetal stages, and how abnormal blood flow solely can lead to CHD. We emphasize studies performed using avian models of heart development, because those models allow for hemodynamic interventions, in vivo imaging, and follow up, while they closely recapitulate heart defects observed in humans. We conclude with recommendations on investigations that must be performed to bridge the gaps in understanding how blood flow alone, or together with other factors, contributes to CHD.

Utilizing the Fourth Dimension for Patient Education in Cardiovascular Surgery

The complex three-dimensional (3D) anatomy of the cardiovascular system presents a steep learning obstacle to patients in understanding cardiovascular diseases and surgical procedures. Although 3D printed models have become very popular in surgical education, 2D cross-sections remain standard in clinical practice due to costs and availability. In this report, we demonstrate how the free 3D modeling software Meshmixer can be used to add a fourth dimension to patient education by exploiting interactive 3D modeling. This report serves as proof of concept for the feasibility and potential utility of interactive 3D modeling as an inexpensive tool for cardiovascular surgery patient education.

Computational fluid dynamics: a primer for congenital heart disease clinicians

Computational fluid dynamics has become an important tool for studying blood flow dynamics. As an in-silico collection of methods, computational fluid dynamics is noninvasive and provides numerical values for the most important parameters of blood flow, such as velocity and pressure that are crucial in hemodynamic studies. In this primer, we briefly explain the basic theory and workflow of the two most commonly applied computational fluid dynamics techniques used in the congenital heart disease literature: the finite element method and the finite volume method. We define important terminology and include specific examples of how using these methods can answer important clinical questions in congenital cardiac surgery planning and perioperative patient management.

The Cavoatrial Anastomosis Procedure in Anomalous Connection of Superior Vena Cava to Left Atrium

Anomalous connection of the superior vena cava to the morphologic left atrium is a rare congenital systemic venous abnormality. As opposed to pulmonary venous anomalies, the significant right-to-left shunt in these patients warrants a correction early in life. Optimal repair technique for combined pulmonary and systemic venous anomalies is not defined yet. Herein, we describe a neonate with such a diagnosis treated with cavoatrial anastomosis, known as Warden procedure with excellent results.

Using Cone and Plate(let) Analyzer to Predict Bleeding in Cardiac Surgery

The cone and plate(let) analyzer is an established method for assessing platelet function. It evaluates adherence of platelets on an extracellular matrix, expressed as a percentage of surface coverage and the average size of the aggregates. The purpose of this study was to determine the applicability of the cone and plate(let) analyzer in monitoring platelet function and predicting postoperative bleeding. The relationship between postoperative bleeding, perioperative platelet function, and other parameters was studied. A significant decrease in surface coverage was detected upon establishment of cardiopulmonary bypass (from 6.9% ± 3.9% to 4.7% ± 1.7%) with a return to preoperative values at the end of surgery. Preoperative average size and surface coverage were the only parameters that significantly and linearly correlated with postoperative bleeding. Patients with an aggregate average size < 20 μm2 had a significantly higher incidence of severe bleeding (> 965 mL) than those with a size > 20 μm2 (44% vs. 0%), and a higher mean blood loss (908 ± 322 mL vs. 337 ± 78 mL). Similar results were obtained for surface coverage < 5%, indicating the predictive value of these parameters. Preoperative platelet function as evaluated by the cone and plate(let) analyzer is an independent risk factor determining postoperative bleeding.

Repair of Tetralogy of Fallot in Children Less Than 4 kg Body Weight

We reviewed our experience of surgical repair of Tetralogy of Fallot (TOF) in children weighing less than or equal to 4 kg to compare outcome of early palliation versus complete repair as the initial surgical approach. Seventy-six patients, weighing ≤ 4 kg, with TOF surgery between January 2005 and September 2013 were included in this single-center retrospective study. Twenty-five patients who underwent initial shunt procedure followed by later full repair were compared to 51 patients who had primary full repair for differences in baseline characteristics and outcomes. Shunt group patients had lower body weight, 2.76 ± 0.69 versus 3.11 ± 0.65 (kg), p = 0.03, and lower preoperative oxygen saturations, 82 ± 7 versus 90 ± 6 (%), p = 0.0001, than full repair group. A higher number of surgical procedures per patient was recorded in shunt patients, 2.29 ± 0.59 versus 1.27 ± 0.49, p = 0.00002. Thirteen of 51 patients in the full repair group required a repeat surgery. Catheterization procedures were performed in 12 patients in shunt and in 15 patients in full repair group, with interventional angioplasty in three and 11, respectively, p ≥ 0.05. Two patients, both in the shunt group, died after the surgery. Early full repair had longer hospital stay but significantly less hospitalizations 1.95 ± 1.3 versus 2.5 ± 1.4, p = 0.03. Initial complete repair of TOF in small children yielded favorable outcome with significantly less surgical procedures and subsequent hospitalizations. Cath laboratory re-interventions for residual defects were similar after both surgical approaches, and type of initial surgery does not predict freedom from re-intervention.

Pretreatment of synthetic vascular grafts with heparin before implantation, a simple technique to reduce the risk of thrombosis

Thrombosis of synthetic grafts commonly used in cardiovascular surgery is a major complication. We examined whether pretreatment of the graft with heparin reduces the risk of early thrombosis. A circuit was assembled to compare two pairs of shunts simultaneously in the same animal. The study shunts were pretreated with heparin. After 2 hours of circulation, clot formation was evaluated by image analysis techniques. The pretreated grafts had fewer blood clots adhered to the surface by direct visual inspection. The image analysis showed 5 vs. 39 clots, 0.01% vs. 1.8% clotted area, and 62 vs. 5630 clot pixel area between the treated and non-treated grafts respectively, p < 0.05. Pretreatment of the synthetic graft with heparin prior to implantation reduces the risk of early clot formation. This simple practice might be helpful to prevent initial thrombosis of the graft and later occlusion.

In vivo quantification of clot formation in extracorporeal circuits

Clot formation is a common complication in extracorporeal circuits. In this paper we describe a novel method for clot formation analysis using image processing. We assembled a closed extracorporeal circuit and circulated blood at varying speeds. Blood filters were placed in downstream of the flow, and clotting agents were added to the circuit. Digital images of the filter were subsequently taken, and image analysis was applied to calculate the density of the clot. Our results show a significant correlation between the cumulative size of the clots, the density measure of the clot based on image analysis, and flow duration in the system.

The neonatal hypoplastic aortic arch: decisions and more decisions

Neonatal patients with hypoplasia of the aortic arch constitute a heterogeneous group with a wide spectrum of severity. The milder end of the spectrum comprises patients with aortic coarctation and isthmus hypoplasia. At the other end of the spectrum are patients with severe transverse arch hypoplasia or hypoplastic left heart syndrome. The aim of this paper is to discuss the various strategies and surgical approaches available for this group of patients, focusing on the surgical decisions that influence individual patient management. Many of the things discussed are applicable to any neonatal arch problem. We also describe and discuss in detail our surgical technique for patients who undergo neonatal repair of a hypoplastic aortic arch via median sternotomy.

Management of intracranial hemorrhage in a child with a left ventricular assist device

Pediatric patients bridged to heart transplant with LVADs require chronic anticoagulation and are at increased risk of hemorrhagic complications, including intracranial hemorrhage. In this population, intracranial hemorrhage is often fatal. We report a case of successful management of a five-yr-old-boy with DCM on an LVAD who developed a subdural hematoma. We initially chose medical management, weighing the patient's high risk of thromboembolism from anticoagulation reversal against the risk of his chronic subdural hematoma. When head CT showed expansion of the hemorrhage with increasing midline shift, we chose prompt surgical evacuation of the hematoma with partial reversal of anticoagulation, given the increased risk of acute deterioration. The patient ultimately received an orthotopic heart transplant and was discharged with no permanent neurological complications. This represents a case of a pediatric patient on an LVAD who survived a potentially fatal subdural hematoma and was successfully bridged to cardiac transplantation.

Single dose myocardial protection technique utilizing del Nido cardioplegia solution during congenital heart surgery procedures

BACKGROUND

The single dose cardioplegia technique for myocardial protection during congenital heart surgery is a viable alternative to multidose protocols.

METHODS

Thirty-four pediatric patients with aortic cross clamp times greater than 90 minutes were grouped by modified adult (MA) multidose solution or del Nido (dN) single dose solution. Also, data from eight patients where the cross clamp times were greater than two hours on one dose of dN solution were included.

RESULTS

In the 90-minute plus arm of the study, there were no significant differences between the groups when comparing the risk adjustment for congenital heart surgery (RACHS) (p=0.6), cardiopulmonary bypass times (CPB) (p=0.5), aortic cross camp times (p=0.5), weights (p=0.7) and number of intraoperative exogenous blood units (p=0.5). There were significant differences between the groups (p<0.05) in the number of cardioplegia doses and with perioperative glucose levels. In the greater than two hours group, the incidence of complete heart block (CHB) was 0.125% and there were no deaths or mechanical circulatory support (MCS) devices used.

CONCLUSION

del Nido cardioplegia solution is a reasonable tool for myocardial protection during congenital heart surgery that significantly decreased the number of cardioplegic interventions and perioperative glucose values in our study groups.

Left ventricular pacing lead insertion via the coronary sinus cardioplegia cannula: a novel method for temporary biventricular pacing during reoperative cardiac surgery

OBJECTIVE

Temporary biventricular pacing to treat low output states after cardiac surgery is an active area of investigation. Reoperative cases are not studied due to adhesions, which preclude left ventricular mobilization to place epicardial pacing wires. In such patients, inserting a temporary left ventricular lead via the coronary sinus cardioplegia cannula may allow for biventricular pacing. We developed a novel technique for intraoperative left ventricular lead placement.

METHODS

Eight domestic pigs underwent median sternotomy and pericardiotomy. Temporary pacing wires were sewn to the right atrium and right ventricle. Complete heart block was induced by ethanol ablation of the atrioventricular node. A 13-French retrograde cardioplegia catheter was introduced via the right atrial free wall into the coronary sinus. A 6-French left ventricular pacing lead was inserted into the cardioplegia catheter and advanced into the coronary sinus during biventricular pacing until left ventricular capture was detected by electrocardiogram and arterial pressure monitoring. Left ventricular capture success rate and electrical performance were recorded during five placement attempts.

RESULTS

Left ventricular capture was achieved on 80% of insertion attempts. Left ventricular capture without diaphragmatic pacing was achieved in 7 pigs. Lead tip locations were mostly in lateral and posterior basal coronary vein branches. There were no arrhythmias, bleeding, or perforation associated with lead insertion.

CONCLUSIONS

Intraoperative biventricular pacing with a left ventricular pacing lead inserted via the coronary sinus cardioplegia cannula is feasible, using standard instrumentation and without requiring cardiac manipulation. This approach merits further study in patients undergoing reoperative cardiac surgery.

Stuck Bioprosthetic Aortic Valve--A New Entity? A Case Report

We describe herein a case of bioprosthetic valve malfunction, which closely imitates a stuck valve. Although the term "stuck" was used originally for the immovable mechanical valve leaflets, the echocardiographic manifestation of this malfunction is similar to those of a mechanical one. The clinical presentation of the stuck bioprosthesis is, however, far more benign than a stuck mechanical valve. Familiarity with this entity is important.

Beneficial effect of aspirin on renal function in patients with renal insufficiency postcardiac surgery

AIM

Renal function is one of the most important prognostic factors following cardiac surgery. Whether aspirin affects cardiopulmonary bypass related renal injury is investigated in this study.

METHODS

Ninety-four patients with impaired renal function (creatinine = or >1.5 mg/dl) undergoing coronary artery bypass grafting (CABG) were categorized into 2 groups according to aspirin administration before surgery. Serum creatinine, urinary output and creatinine clearance along with other perioperative factors were compared between the 2 groups prior to surgery, 24 hours and 48 hours following cardiopulmonary bypass.

RESULTS

Creatinine levels increased significantly in the second postoperative day only in the non-aspirin (control) group (3.7+/-1.6 vs 2.9+/-1.7 mg/dl, p=0.03). Aspirin (study) group had lower creatinine levels in day 1 (p=0.03) and day 2 (p=0.001). Furthermore, in the study group creatinine clearance was higher in day 1 (34.3+/-14.3 vs 30.9+/-13.1 ml/min, p=0.01) and in day 2 (32.6+/-13.8 vs 26.4+/-9.8 ml, p<0.0001). Creatinine levels at discharge were elevated compared to the preoperative levels in the control group (p=0.01). However, the study group had lower creatinine levels at discharge (2.6+/-1.4 vs 3.8+/-1.6 mg/dl, p<0.0001). Urinary output was higher in the study group in the first postoperative day compared to the control group (p=0.01). Postoperative bleeding was slightly increased in the study group compared to the control group (760+/-230 ml vs 530+/-210 ml, p=0.01).

CONCLUSIONS

Continuation of aspirin administration until the day of surgery may have a protective effect against renal injury resulting from cardiopulmonary bypass, with only a negligible increase in bleeding. Possible explanations for this effect are antiplatelet activity of aspirin during cardiopulmonary bypass causing inhibition of vasoconstrictive agents like thromboxane, and improvement of renal perfusion by reducing blood viscosity.

Aspirin decreases vascular endothelial growth factor release during myocardial ischemia

BACKGROUND

Vascular Endothelial Growth Factor (VEGF) is an important angiogenesis factor involved in pathophysiology of cardiovascular diseases. Controlling this factor's level in the serum might have significant prognostic outcomes.

METHODS

Twenty-four patients undergoing coronary artery bypass grafting were prospectively categorized into two groups according to aspirin administration before surgery. Vascular Endothelial Growth Factor levels were compared and correlated and adjusted with platelets count between two groups in the serum, before and after the surgery. Serum creatine kinase (CK) levels were determined before and after the operation in parallel to other clinical data.

RESULTS

Vascular Endothelial Growth Factor levels were significantly lower in patients of the aspirin group compared to those of the non-aspirin group; 94+/-61 vs. 241+/-118 pg/ml, p=0.0003, respectively, this-despite an absence of difference in the platelet count between the groups. These titers decreased postoperatively in both groups, 94+/-61 to 10+/-9 pg/ml, p=0.001 in aspirin group and from 241+/-118 to 84+/-54 pg/ml, p=0.001 in control group. Serum creatine kinase levels were higher in the non-aspirin group, 214+/-83 u/l compared to 70+/-32 u/l in the aspirin group. Creatine kinase levels increased significantly postoperatively in both groups; however, the aspirin group had a significantly lower creatine kinase levels compared to non-aspirin group, 107+/-51 vs. 401+/-127 u/l, respectively, p=<0.0001. A significant correlation was seen between VEGF levels and platelets count in both groups, r=0.5.

CONCLUSIONS

Aspirin treated patients have lower Vascular Endothelial Growth Factor titer levels in the perioperative course. This difference between the aspirin and the non-aspirin group is not accounted for by the platelets count.

Platelet Function Changes as Monitored by Cone and Plate(let) Analyzer during Beating Heart Surgery

BACKGROUND

Off-pump coronary artery bypass (OPCAB) is believed to reduce cardiopulmonary bypass (CPB)-related complications, including platelet damage. A hypercoagulable state instead of coagulopathy has been reported following OPCAB surgeries due to CPB. Whether platelet function is changed when the injurious effect of CPB is eliminated was investigated.

METHODS

Platelet function was determined with the cone and plate(let) analyzer (CPA) method. The 2 parameters, average size (AS) and surface coverage (SC) of platelet aggregates, were measured with the CPA method to assess platelet aggregation and adhesion. These parameters were evaluated, and their values were compared at several stages of OPCAB surgery. The correlations of postoperative bleeding with platelet function at different stages of the surgery and with other factors, such as platelet count, hematocrit, and transfusions, were studied.

RESULTS

Both AS and SC increased during several stages of the operation, and postoperative values (mean +/- SD) were significantly higher than preoperative values (30.4 +/- 8.1 microm 2 versus 23.3 +/- 6.9 microm 2 for AS [ P =.02] and 7.6% +/- 3.6% versus 5.2% +/- 1.8% for SC [ P =.04]). The mean total bleeding volume was 875 micro 415 mL. Preoperative AS and SC were the only parameters significantly ( P =.01) and linearly ( r = 0.7) related to postoperative bleeding.

CONCLUSIONS

An increased platelet function, as determined by the CPA method, is found following OPCAB surgery. This phenomenon is probably at least partially responsible for the thrombogenic state after OPCAB surgery. Lack of platelet injury attributed to CPB may divert the system toward a more thrombogenic state. Preoperative platelet function, as evaluated by the CPA method, is an independent risk factor determining postoperative bleeding.

Pericardial fluid and serum VEGF in response to different types of heparin treatment

BACKGROUND

Heparin is an important medication in the treatment of patients with unstable angina pectoris. We designed an observational study to compare the effects of standard heparin (SH) with low molecular weight heparin (LMWH) on vascular endothelial growth factor (VEGF) levels in patients undergoing coronary artery bypass grafting (CABG).

METHODS

Thirty-two patients with unstable angina pectoris undergoing CABG were prospectively categorized into two groups according to the type of heparin administration before surgery. VEGF levels determined by enzyme linked immunosorbent assay (ELISA) were compared between the two groups' blood samples obtained before the surgery and pericardial fluid after pericardial opening.

RESULTS

There was no difference in preoperative characteristics between the two groups. Serum VEGF levels were similar (P=0.3) in patients treated by SH (85+/-55 pg/ml) compared to those treated with LMWH (105+/-64 pg/ml). VEGF levels in the pericardial fluid were significantly raised (P<0.0001) in patients of LMWH group (36+/-13 pg/ml) compared to SH group (13+/-6 pg/ml). A good correlation was observed between VEGF in the serum and platelet count in both SH group (r=0.8) and LMWH group (r=0.7).

CONCLUSIONS

Local response of the ischemic myocardium, as expressed by VEGF levels, differs in patients treated with SH compared to patients treated with LMWH. VEGF levels in pericardial fluid of patients receiving LMWH were 2-3-folds higher than patients in SH group.

Beneficial effect of aspirin on renal function post-cardiopulmonary bypass

Urine thromboxane, plasma creatinine, and creatinine clearance were determined perioperatively in 20 patients undergoing coronary bypass surgery. Ten patients took aspirin until the day of surgery, and 10 discontinued aspirin at least one week before surgery. A significant increase in urine thromboxane following establishment of cardiopulmonary bypass was observed only in the control group. Plasma creatinine increased in the control group on the 1st postoperative day (from 81.9 +/- 13.2 to 97.6 +/- 13.2 micromol.L(-1), p = 0.02) and decreased next day to the preoperative level (82.7 +/- 9 micromol.L(-1), p = 0.03). In the aspirin group, creatinine remained unchanged on the 1st postoperative day (89.4 +/- 14.2 vs. 87.2 +/- 7.7 micromol.L(-1), p = 0.6), and increased significantly on the 2nd day (101.4 +/- 8.5 micromol.L(-1), p = 0.01). The aspirin group had higher creatinine levels (p < 0.0001) and lower creatinine clearance (60.2 +/- 16.5 vs. 82 +/- 25.7 mL.min(-1), p < 0.0001) than the control group on the 2nd postoperative day. A significant positive correlation was seen between urine thromboxane and creatinine on day 2 in both groups (r = 0.6). Aspirin administrated before coronary surgery may have a beneficial effect on renal function, probably mediated by its antiplatelet activity and thromboxane inhibition.

Cardiac surgery in octogenarians--a better prognosis in coronary artery disease

BACKGROUND

Cardiac surgery is being performed with increasing frequency in patients aged 80 years and older.

OBJECTIVES

To examine the long and short-term results of surgery in this age group.

METHODS

We retrospectively investigated 202 consecutive patients aged 80 years or older who underwent cardiac surgery between 1991 and 1999, Ninety-six operations (48%) were urgent.

RESULTS

The study group comprised 140 men (69%) and 62 women (31%) with a mean age of 82.1 years (range 80-89). Preoperatively, 120 patients (59%) had unstable angina, 37 (18%) had left main coronary artery disease, 22 (11%) had renal failure, 17 (8.5%) had a history of stroke and 13 (6.5%) had previous cardiac surgery. Hospital mortality for the whole group was 7.4%. Postoperative complications included: re-exploration for bleeding in 15 (7.4%), stroke in 8 (4%), sternal wound infection in 3 (1.5%), low cardiac output in 17 (8.4%), new Q wave myocardial infarction in 5 (2.5%), renal failure in 17 (8.5%), and atrial fibrillation in 71 (35%). The actuarial survival for patients discharged from the hospital was 66% at 5 years and 46% at 8 years. The type of surgical procedure was significantly associated with increased early mortality (coronary artery bypass grafting only in 2.9%, CABG + valve in 16.1%, valve only in 16.7%; P = 0.01). Significant predictors (P < 0.05) for late mortality included type of surgical procedure, congestive heart failure, and postoperative low cardiac output.

CONCLUSIONS

When appropriately applied in selected octogenarians, cardiac surgery can be performed with acceptable mortality and good long-term results.

The surgical approach to infective endocarditis: 10 year experience

BACKGROUND

About 40% of patients with infective endocarditis will require surgical treatment. The guidelines for such treatment were formulated by the American College of Cardiology and American Heart Association in 1998.

OBJECTIVES

To examine our experience with surgical treatment of infective endocarditis in light of these guidelines.

METHODS

Surgery was performed in 59 patients with infective endocarditis between 1990 and 1999. The patients' mean age was 48 years (range 13-80). The indications for surgery were hemodynamic instability, uncontrolled infection, and peripheral embolic events. The surgical treatment was based on elimination of infection foci and correction of the hemodynamic derangement. These objectives were met with valve replacement in the majority of patients. Whenever conservative surgery was possible, resection of vegetation and subsequent valve repair were performed and the native valve was preserved.

RESULTS

Six patients (10%) died perioperatively from overwhelming sepsis (n = 3), low cardiac output (n = 2) and multiogran failure (n = 1). The mean hospital stay was 15.6 days. Of 59 patients, 47 (80%) underwent valve replacement and in 11 (19%) the surgical treatment was based on valve repair. After 1 year of follow-up there was no re-infection.

CONCLUSION

The new guidelines for surgical treatment of infective endocarditis allow better selection of patients and timing of surgery for this aggressive disease, which consequently decreases the mortality rate. Valve repair is feasible and is preferred whenever possible. According to the new guidelines, patients with neurologic deficit in our series would not have been operated upon, potentially decreasing the operative mortality to 7%.

Impaired oxygenation and increased hemolysis after cardiopulmonary bypass in patients with glucose-6-phosphate dehydrogenase deficiency

BACKGROUND

The purpose of this study was to determine whether the damaging effects of cardiopulmonary bypass, ischemia, and reperfusion would be more pronounced in patients with glucose-6-phosphate dehydrogenase deficiency undergoing cardiac surgery.

METHODS

Forty-two patients with glucose-6-phosphate dehydrogenase deficiency underwent open heart procedures using cardiopulmonary bypass. This group was matched with a control group of identical size for comparison of operative course and postoperative outcome. The perioperative variables were compared between the two groups using univariate and multivariate analysis.

RESULTS

The duration of ventilation after the operation was significantly longer in the glucose-6-phosphate dehydrogenase-deficient group (13.7 +/- 7.6 hours versus 7.7 +/- 2.8 hours; p < 0.0001). Minimal value of arterial oxygen tension was lower in patients with glucose-6-phosphate dehydrogenase deficiency (66 +/- 12 mm Hg versus 85 +/- 14 mm Hg; p < 0.0001), and more cases of hypoxia (arterial oxygen tension < 60 mm Hg) were found in this group (11 versus 1; p = 0.001). Compared with the control group, patients with glucose-6-phosphate dehydrogenase deficiency had significantly elevated hemolytic indices expressed by bilirubin levels (26 +/- 10 mmol/L versus 17 +/- 6.7 mmol/L; p < 0.0001) and lactic dehydrogenase levels (970 +/- 496 U/L versus 505 +/- 195 U/L; p < 0.0001). They also required significantly more blood transfusion perioperatively (1.9 +/- 1.4 packed cell units/patient versus 0.8 +/- 1.0 packed cell units/patient; p = 0.0001).

CONCLUSIONS

Patients with glucose-6-phosphate dehydrogenase deficiency who are undergoing cardiac surgery may have a more complicated course with a longer ventilation time, more hypoxia, increased hemolysis, and a need for more blood transfusion. Because this difference may be caused by subnormal free radical deactivation, strategies that minimize bypass in general and free radicals specifically may be beneficial.