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Biomedical subjects

Robert C Ashton

Publications and source records attributed to Robert C Ashton.

14 recordsLinked to original sources
PubMed2006

Assessment of independent predictors for long-term mortality between women and men after coronary artery bypass grafting: are women different from men?

OBJECTIVE: The long-term mortality of coronary artery bypass grafting in women in not certain. The purpose of this study was to determine and compare risk factors for long-term mortality in women and men undergoing coronary artery bypass grafting. METHODS: Between 1992 and 2002, 3760 consecutive patients (2598 men and 1162 women) underwent isolated coronary artery bypass grafting. Long-term survival data were obtained from the National Death Index (mean follow-up, 5.1 +/- 3.2 years). Multivariable Cox regression analysis was performed, including 64 preoperative, intraoperative, and postoperative factors separately in women and men. RESULTS: There were no differences in in-hospital mortality (2.7% in men vs 2.9% in women, P = .639) and 5-year survival (82.0% +/- 0.8% in men vs 81.1% +/- 1.3% in women, P = .293). After adjustment for all independent predictors of long-term mortality, female sex was an independent predictor of improved 5-year survival (hazard ratio, 0.82; 95% confidence interval, 0.71-0.96; P = .014). Twenty-one independent predictors for long-term mortality were determined in men, whereas only 12 were determined in women. There were 9 common risk factors (age, ejection fraction, diabetes mellitus, > or =2 arterial grafts, postoperative myocardial infarction, deep sternal wound infection, sepsis and/or endocarditis, gastrointestinal complications, and respiratory failure); however, their weights were different between women and men. Malignant ventricular arrhythmias, calcified aorta, and preoperative renal failure were independent predictors only in women. Emergency operation, previous cardiac operation, peripheral vascular disease, left ventricular hypertrophy, current and past congestive heart failure, chronic obstructive pulmonary disease, body mass index of greater than 29, preoperative dialysis, thrombolysis within 7 days before coronary artery bypass grafting, intraoperative stroke, and postoperative renal failure were independent predictors only in men. CONCLUSIONS: Despite equality between sexes in early outcome and superiority of female sex in long-term survival, there were 3 independent predictors for long-term mortality after coronary artery bypass grafting unique for women compared with 12 for men. Clinical decision making and follow-up should not be influenced by stereotypes but by specific findings.

Aged↗
PubMed2006

Does bilateral internal thoracic artery grafting increase long-term survival of diabetic patients?

BACKGROUND: The purpose of the present study was to determine whether long-term survival in diabetic patients increased after bilateral internal thoracic artery (BITA) coronary bypass compared with matched patients with single internal thoracic artery (SITA) coronary bypass. METHODS: The propensity for BITA was determined using logistic regression analysis and each BITA patient was matched with one SITA patient. Between January 1992 and March 2002, 980 matched diabetic patients (490 BITA versus 490 SITA) underwent coronary artery bypass surgery. Long-term survival data were obtained from the National Death Index (mean follow-up, 4.7 +/- 3.0 years). Groups were compared by Cox proportional hazard models and Kaplan-Meier survival plots. RESULTS: Multivariate Cox regression analysis determined that BITA grafting had no significant effect on long-term survival (hazard ratio 0.89, 95% confidence interval: 0.69 to 1.14, p = 0.343). There were no differences in 30-day mortality (3.9% for BITA versus 3.7%, p = 0.999) and major postoperative complications except for length of stay (11.4 days for BITA versus 12.7 days, p < 0.001). Five-year survival rate was 79.9% in the BITA group and 75.7% in the SITA group (p = 0.252). There was no difference in 5-year survival rate between matched patients younger than 60 or from 70 to 79 years old. However, BITA patients aged 60 to 69 years had better 5-year survival rates (84.1% versus 71.0%, p = 0.0196), whereas the opposite was observed in patients aged more than 79 years (5-year survival for BITA 43.1% versus 70.0%, p = 0.016). CONCLUSIONS: Bilateral internal thoracic artery grafting had no significant effect on long-term survival for diabetic patients, but it may increase long-term survival in patients aged 60 to 69 years, whereas SITA grafting may be beneficial for patients more than 79 years old.

Age Factors↗
PubMed2005

Preoperative prediction of long-term survival after coronary artery bypass grafting in patients with low left ventricular ejection fraction.

OBJECTIVE: We aimed to develop multivariable models of preoperative risk factors that predict long-term survival after coronary artery bypass grafting in patients with ejection fraction 25% or less. METHODS: We retrospectively evaluated 544 consecutive patients with ejection fraction 25% or less who underwent coronary artery bypass grafting from 1992 to 2002 at a single institution. Long-term survival data (mean follow-up 4.1 years) were obtained from the National Death Index. Multivariable Cox regression analysis was performed to construct a predictive score for long-term mortality. A split-sample approach was also used building a model on a training group (n = 360); this model was then tested on a separate validation group (n = 184). RESULTS: From the entire database, the predictive score was calculated according to the following equation: 0.430(if past congestive heart failure) + 0.049(age in years) + 0.507(if peripheral vascular disease) + 0.580(if emergency operation) + 0.366(if chronic obstructive pulmonary disease). The 5-year survivals of the predictive score quartiles were 82.3%, 78.2%, 65.5%, and 45.5% (P < .0001). The model based on the training group had four independent predictors for long-term mortality (the same as the listed equation except for past congestive heart failure). The 5-year survival rates of the quartiles were 90.1%, 75.4%, 64.3%, and 49.2% in the training group (P < .0001) and 77.4%, 71.2%, 65.8%, and 45.5% in the validation group (P = .0001). CONCLUSION: Coronary artery bypass grafting in patients with severe ischemic cardiomyopathy achieves satisfactory midterm and long-term survival in selected patients. This new score, which is based on long-term data from a large number of patients, may aid clinicians in selecting therapeutic interventions for patients with ischemic cardiomyopathy.

Aged↗
PubMed2005

The LapSim: a learning environment for both experts and novices.

BACKGROUND: Simulated environments present challenges to both clinical experts and novices in laparoscopic surgery. Experts and novices may have different expectations when confronted with a novel simulated environment. The LapSim is a computer-based virtual reality laparoscopic trainer. Our aim was to analyze the performance of experienced basic laparoscopists and novices during their first exposure to the LapSim Basic Skill set and Dissection module. METHODS: Experienced basic laparoscopists (n=16) were defined as attending surgeons and chief residents who performed >30 laparoscopic cholecystectomies. Novices (n=13) were surgical residents with minimal laparoscopic experience. None of the subjects had used a computer-based laparoscopic simulator in the past. Subjects were given one practice session on the LapSim tutorial and dissection module and were supervised throughout the testing. Instrument motion, completion time, and errors were recorded by the LapSim. A Performance Score (PS) was calculated using the sum of total errors and time to task completion. A Relative Efficiency Score (RES) was calculated using the sum of the path lengths and angular path lengths for each hand expressed as a ratio of the subject's score to the worst score achieved among the subjects. All groups were compared using the Kruskal-Wallis and Mann-Whitney U-test. RESULTS: Novices achieved better PS and/or RES in Instrument Navigation, Suturing, and Dissection (p<0.05). There was no difference in the PS and RES between experts and novices in the remaining skills. CONCLUSION: Novices tended to have better performance compared to the experienced basic laparoscopists during their first exposure to the LapSim Basic Skill set and Dissection module.

Clinical Competence↗
PubMed2005

A novel drill set for the enhancement and assessment of robotic surgical performance.

BACKGROUND: There currently exist several training modules to improve performance during video-assisted surgery. The unique characteristics of robotic surgery make these platforms an inadequate environment for the development and assessment of robotic surgical performance. METHODS: Expert surgeons (n=4) (>50 clinical robotic procedures and >2 years of clinical robotic experience) were compared to novice surgeons (n=17) (<5 clinical cases and limited laboratory experience) using the da Vinci Surgical System. Seven drills were designed to simulate clinical robotic surgical tasks. Performance score was calculated by the equation Time to Completion + (minor error) x 5 + (major error) x 10. The Robotic Learning Curve (RLC) was expressed as a trend line of the performance scores corresponding to each repeated drill. RESULTS: Performance scores for experts were better than novices in all 7 drills (p<0.05). The RLC for novices reflected an improvement in scores (p<0.05). In contrast, experts demonstrated a flat RLC for 6 drills and an improvement in one drill (p=0.027). CONCLUSION: This new drill set provides a framework for performance assessment during robotic surgery. The inclusion of particular drills and their role in training robotic surgeons of the future awaits larger validation studies.

Clinical Competence↗
PubMed2004

Antegrade endovascular repair of a coarctation-associated aneurysm through an upper hemi-sternotomy.

Late aneurysm formation is a well-described complication after surgical correction of aortic coarctation. Endovascular repair of such aneurysms avoids the morbidity of conventional reoperative thoracic surgery. We describe a unique case of antegrade endovascular repair of a distal coarctation-associated aneurysm with vascular access acquired through the aortic arch by an upper hemi-sternotomy.

Aged↗
PubMed2004

Robotically assisted left ventricular epicardial lead implantation for biventricular pacing: the posterior approach.

Patients with congestive heart failure and altered interventricular conduction enjoy improvements in quality of life and ventricular function after successful resynchronization therapy with biventricular pacing. Technical limitations owing to individual coronary sinus and coronary venous anatomy result in a 10% to 15% failure rate of left ventricular (LV) lead placement through percutaneous approaches. To provide a minimally invasive option for these patients with LV lead failures, we developed a technique of endoscopic, epicardial LV lead implantation with the use of the da Vinci robotic system. The surgical approach targets the posterolateral wall through a novel posterior approach.

Cardiac Pacing, Artificial↗
PubMed2004

Heterogeneity of the vasoconstrictor effect of vasopressin in septic shock.

OBJECTIVE: To determine whether pressor doses of vasopressin impair organ blood flow in endotoxic shock. DESIGN: Graded doses of vasopressin or phenylephrine, starting at the clinically recommended doses for pressure support in septic shock, were intravenously infused during endotoxic shock. SETTING: University hospital surgical research laboratory. SUBJECTS: Twelve random-bred female Yorkshire pigs. INTERVENTIONS: We measured mean arterial pressure, cardiac output, heart rate, pulmonary artery occlusion pressure, and carotid, mesenteric, renal, and iliac blood flows. MEASUREMENTS AND MAIN RESULTS: Low doses of vasopressin (typically used in the clinical management of septic shock) raised arterial pressure by increasing systemic vascular resistance without a significant preferential effect in the circulations measured. However, moderately greater doses of vasopressin had a very heterogeneous vasoconstrictor action; although there was no significant vasoconstriction in the carotid and iliac circulations, mesenteric and renal blood flows decreased markedly. Furthermore, at pressor doses vasopressin improved cerebral perfusion. CONCLUSIONS: The vasoconstrictor action of exogenous low-dose vasopressin in endotoxic shock does not impair blood flow to any of the vascular beds examined. However, moderately higher doses of vasopressin may induce ischemia in the mesenteric and renal circulations. The data indicate that the safe dose range for exogenous vasopressin in septic shock is narrow and support the current practice of fixed low-dose administration, generally 0.04 units/min and in no case exceeding 0.1 units/min.

Animals↗
PubMed2003

Robotically assisted left ventricular epicardial lead implantation for biventricular pacing.

OBJECTIVES: Ventricular resynchronization might be achieved in a minimally invasive fashion using a robotically assisted, direct left ventricular (LV) epicardial approach. BACKGROUND: Approximately 10% of patients undergoing biventricular pacemaker insertion have a failure of coronary sinus (CS) cannulation. Rescue therapy for these patients currently is limited to standard open surgical techniques. METHODS: Ten patients with congestive heart failure (New York Heart Association class 3.4 +/- 0.5) and a widened QRS complex (184 +/- 31 ms) underwent robotic LV lead placement after failed CS cannulation. Mean patient age was 71 +/- 12 years, LV ejection fraction (EF) was 12 +/- 6%, and LV end-diastolic diameter was 7.1 +/- 1.3 cm. Three patients had previous cardiac surgery, and five patients had a prior device implanted. RESULTS: Nineteen epicardial leads were successfully placed on the posterobasal surface of the LV. Intraoperative lead threshold was 1.0 +/- 0.5 V at 0.5 ms, R-wave was 18.6 +/- 8.6 mV, and impedance was 1,143 +/- 261 ohms at 0.5 V. Complications included an intraoperative LV injury and a postoperative pneumonia. Improvements in exercise tolerance (8 of 10 patients), EF (19 +/- 13%, p = 0.04), and QRS duration (152 +/- 21 ms, p = 0.006) have been noted at three to six months follow-up. Lead thresholds have remained unchanged (2.1 +/- 1.4 V at 0.5 ms, p = NS), and a significant drop in impedance (310 +/- 59 ohms, p < 0.001) has been measured. CONCLUSIONS: Robotic LV lead placement is an effective and novel technique which can be used for ventricular resynchronization therapy in patients with no other minimally invasive options for biventricular pacing.

Aged↗
PubMed2003

Mediastinal mass evaluation using advanced robotic techniques.

The diagnosis and management of mediastinal masses frequently necessitates biopsy and surgical resection. The use of videothorascopic techniques has broadened the surgeon's ability to evaluate and treat such tumors using a minimally invasive approach. We describe herein the use of the da Vinci Robotic Surgical System for evaluating a mediastinal mass in a young woman.

Adult↗
PubMed2003

Totally endoscopic robotic thymectomy for myasthenia gravis.

The current recommendations for treating myasthenia gravis include surgical thymectomy for patients between puberty and 60 years of age. This is a report of a new method for surgical thymectomy using the robotic da Vinci surgical system for a totally endoscopic approach. This new procedure combines the potential advantages of minimally invasive methods with the efficacy of open procedures.

Adult↗
PubMed2002

Totally endoscopic atrial septal defect repair with robotic assistance.

BACKGROUND: The development of minimally invasive cardiac surgery has been characterized by the performance of increasingly complex operations through progressively smaller incisions. Computer (robotic) enhancement has emerged as a potential facilitator of these procedures, initially by providing enhanced endoscopic camera control and, more recently, by allowing the manipulation of surgical instruments through limited thoracic incisions. This report describes the next step in this progression, namely the performance of an atrial septal defect (ASD) repair entirely through thoracoscopic port incisions. This represents the first U.S. application of robotic technology for totally endoscopic open-heart surgery. MATERIALS AND METHODS: A 33-year-old woman with a secundum atrial septal defect underwent totally endoscopic repair through four port incisions by means of the Da Vinci (Intuitive Surgical, Mountain View, CA) robotic surgical system. Cardiopulmonary bypass was achieved peripherally (femoral Estech endoaortic balloon cannula; femoral and right internal jugular venous Bio-medicus cannulae). The myocardium was protected with antegrade cold blood cardioplegia delivered through the distal port of the arterial cannula. After port insertion, the entire operation, including pericardiotomy, bicaval occlusion, atriotomy, atrial septopexy, and atrial closure, was performed by computer-aided control of a camera and two instrument arms manipulated by a surgeon seated 15 feet away. The fourth port was used for suction and suture passage by the patient-side assistant. The aortic cross-clamp time was 43 minutes, and the postoperative transesophageal echocardiogram demonstrated normal ventricular function and the absence of interatrial shunting. The patient was extubated on the night of surgery, was ambulatory within 15 hours, and was discharged on the morning of postoperative day 3, 63 hours after the procedure. At 30-day follow-up, the patient was well and without complaints, and transthoracic echocardiogram confirmed the continued absence of interatrial shunting. CONCLUSIONS: Computer-aided robotic surgical technology can be used to perform open-heart procedures with a totally endoscopic approach. The benefits of this approach may include decreased perioperative pain, decreased recovery times, and improved cosmesis and patient acceptance. Clinical trials currently in progress will demonstrate whether this technology will be of reproducible value in the management of patients with intracardiac disease on a larger scale.

Adult↗