Comparison of skill training with robotic systems and traditional endoscopy: implications on training and adoption.

BACKGROUND: Robotic systems are being used by an increasing number of surgeons. This environment is markedly different from that of traditional surgery and involves videoscopic guidance, remote surgical control, and the loss of haptic feedback. Defining how surgeons learn with these systems is necessary to establish training protocols for this technology. This study compared the learning curve for a robotic surgical system with that of traditional endoscopy in the performance of two standardized skill drills. MATERIALS AND METHODS: Twenty participants (average age 27 +/- 4 years, six females) repeated two standardized endoscopic dexterity and depth perception drills for 15 repetitions with the ZEUS robotic surgical system and manual endoscopic instruments (MAN). A score combining time and precision was given for each repetition. The learning curves and overall performance with and without robotic assistance were compared. RESULTS: For both MAN and ZEUS, improvements in performance were significantly greatest during the first five repetitions (P < 0.01, for both). Participants reached the training curve plateau faster with ZEUS than with conventional instruments (8th versus 10th for both drills). Using robotic assistance, dominant and non-dominant hand performance were statistically similar. The number of errors committed with ZEUS were significantly fewer for drill two (0.09 errors/repetition versus 0.24 errors/repetition, P = 0.002) compared to manual technique. CONCLUSIONS: This study demonstrated that training curves for conventional and robotic-assisted systems are remarkably similar. This should prove useful in the training and education of this new technology. This study further suggested that robotics may increase ambidexterity by improving non-dominant hand performance.

Amplatzer atrial septal defect occluder for pediatric patients: radiographic appearance.

PURPOSE: To describe the chest radiographic appearance of the Amplatzer septal occluder (ASO) (AGA Medical Corporation, Golden Valley, Minn) for atrial septal defects (ASDs) in pediatric patients. MATERIALS AND METHODS: Two radiologists independently reviewed frontal and lateral chest radiographs obtained in young patients 24 hours after transcatheter ASD closure with the ASO. The appearance (flat disks or dots) and location of the ASO were recorded. The location was related to that of a thoracic vertebral body on frontal and lateral chest radiographs and to a line drawn between the anterior margin of the right hilum and the posterior margin of the inferior vena cava (hilar-caval line) on lateral radiographs; this line corresponded to the expected position of the interatrial septum. The relationship between ASO appearance and patient age was assessed with logistic regression and cumulative probability plots. RESULTS: Sixty-eight pediatric patients (age range, 1 month to 18 years; mean age, 4.2 years; 24 boys and 44 girls) were included. On frontal radiographs, the ASO center projected between T7 and T9, either to the right of or over the spinous processes of the vertebral body. On lateral radiographs, the ASO projected over (n = 66) or anterior to (n = 2) the hilar-caval line. On frontal radiographs, it appeared as one or two flat disks (n = 61) or as two metallic dots (n = 7). On lateral radiographs, it appeared as two flat disks (n = 54) or as two metallic dots (n = 14). The relationship between increasing patient age and the metallic dot appearance on frontal and lateral radiographs and on the combination of frontal and lateral radiographs was highly significant in each case (P < .001, likelihood ratio chi(2) test), with r(2) values of 0.35, 0.20, and 0.28, respectively. ASDs were successfully occluded with the ASO in all patients except one, in whom trivial shunting was seen at 12-month follow-up. CONCLUSION: The ASO in pediatric patients has a characteristic radiographic appearance when properly positioned.

Surgical robotics: impact of motion scaling on task performance.

BACKGROUND: Robotic systems have been shown to enhance surgical dexterity, and the advantage has been hypothesized to result from the removal of tremor and addition of motion scaling. But these purported gains over traditional laparoscopic instrumentation have not been quantified. This study was designed to compare the surgical accuracy between conventional laparoscopic instruments and a robotic surgical system and evaluate the importance of tremor filtration (TF) and motion scaling (MS) in these robotic systems. STUDY DESIGN: Fifteen participants with no previous surgical experience were enrolled. To simulate microsurgical techniques, a 29-gauge needle was used to puncture the center of 6 microscopic archery targets (circle diameters 0.5, 1.5, and 2.5 mm). The robotic system was configured to three different degrees of MS and compared with the unassisted laparoscopic platforms in accuracy. RESULTS: Accuracy with robotic assistance with TF alone (1:1 MS) was not significantly different from unassisted laparoscopic control. Both moderate (2.5:1) and fine (7:1) MS significantly improved accuracy over traditional laparoscopic control (p < 0.001 for both). Robotic assistance with MS equalized the performance of both hands (p = 0.03) in precision, and manual laparoscopy demonstrated no statistical difference in handedness (p = 0.80). CONCLUSIONS: Motion scaling, rather than tremor filtration, plays the major role in the enhanced accuracy seen in robotic surgical systems. Robotic assistance with MS significantly improved accuracy above laparoscopic instruments alone and robotic assistance with tremor filtration alone. MS also creates ambidexterity in an otherwise unidextrous population, optimizing the surgeon's ability to undertake tasks requiring microsurgical accuracy.

Ventricular function after coronary artery bypass grafting: evaluation by magnetic resonance imaging and myocardial strain analysis.

OBJECTIVE: Magnetic resonance imaging with radiofrequency tissue tagging permits quantitative assessment of regional systolic myocardial strain. We sought to investigate the utility of this imaging modality to quantitatively determine preoperative impairment and postoperative improvement in ventricular function in patients with ischemic heart disease. METHODS: Magnetic resonance imaging with radiofrequency tissue tagging was performed on 6 patients (average age 60.2 +/- 13.7 years) with coronary artery disease and 32 control subjects with no known heart disease. Patients with coronary artery disease underwent imaging before and 3 months after coronary artery bypass grafting. The ventricle was divided into 6 segments within a midventricular plane. Regional 2-dimensional left ventricular circumferential strain was calculated from tagged magnetic resonance images throughout systole. Circumferential strain results were compared in patients before and after and 3 months after coronary artery bypass grafting and also in control subjects. RESULTS: Before the operation circumferential strain identified 100% (10/10) of all regional wall motion abnormalities seen by preoperative ventriculography. Postoperatively, improvements were demonstrated in 56% (20/36) of the regions, and these improvements agreed with viability testing by single-photon emission computed tomography when available. Additionally, preoperative global circumferential strain for the ischemic group was significantly depressed relative to that in control subjects (0.11 +/- 0.05 vs 0.20 +/- 0.03, P <.001). Global circumferential strain correlated with ejection fraction by ventriculography (r = 0.84, P <.01) and improved after coronary artery bypass grafting (0.14 +/- 0.05 vs 0.11 +/- 0.05, P <.01). CONCLUSIONS: Magnetic resonance imaging with radiofrequency tissue tagging permitted circumferential strain calculation. This technology quantitatively demonstrated improvements in left ventricular wall motion after coronary artery bypass grafting for both individual regions and the entire ventricle. This noninvasive method may prove useful in preoperative evaluation and postoperative serial assessment of left ventricular wall motion.

Delayed paraplegia after thoracic and thoracoabdominal aneurysm repair: a continuing risk.

BACKGROUND: Paraplegia or paraparesis after otherwise successful thoracic or thoracoabdominal aortic reconstruction is a devastating complication for patient and physician. Interventions for its prevention have focused primarily on the intraoperative period. We have recently noted a significant incidence of delayed-onset neurologic deficit. METHODS: We reviewed our most recent 5-year experience with thoracic and thoracoabdominal reconstruction to examine the incidence of and potential contributors to delayed paraplegia or paraparesis. RESULTS: Between June 1996 and June 2001, 60 patients (29 men, 31 women) underwent repair of isolated thoracic (n = 26) or thoracoabdominal aortic aneurysm (Crawford I, n = 7; Crawford II, n = 14; Crawford III, n = 12; Crawford IV, n = 1) by the cardiac and vascular surgical services collaboratively. Repair was performed endovascularly in 6, and open with either circulatory arrest in 12, partial left heart bypass in 37, or partial femorofemoral bypass in 5. Operative mortality was 9.3% (5 of 54 patients) for open repair and 0% for endovascular repair. Paraplegia or paraparesis occurred in 6 (10%) patients of which 83.3% (5 of 6) were delayed in onset. All patients with delayed paraplegia or paraparesis had degenerative aneurysms of Crawford extent II (n = 3) or III (n = 2), had intraoperative left heart bypass, and had perioperative spinal drainage. Delayed paraplegia or paraparesis occurred up to 27 days postoperatively, and was associated with a documented episode of hypotension in 60% (3 of 5) of patients. CONCLUSIONS: Improvements in intraoperative management may have reduced immediate paraplegia or paraparesis among vulnerable patients only to leave them at risk of delayed-onset deficit. Postoperative care, including assiduous attention to avoidance of even transient hypotension, must be tailored to this patient population.

Impact of pericardial restraint on right atrial mechanics during acute right ventricular pressure load.

Optimization of right atrial (RA) mechanics is important for maintaining right ventricular (RV) filling and global cardiac output. However, the impact of pericardial restraint on RA function and the compensatory role of the right atrium to changes in RV afterload remain poorly characterized. In eight open-chest sheep, RA elastance (contractility) and chamber stiffness were measured (RA pressure-volume relations) at baseline and during partial pulmonary artery (PA) occlusion. Data were collected before and after pericardiotomy. With the pericardium intact and partial PA occlusion, RA elastance increased by 28% (P < 0.04), whereas RA stiffness tended to rise (P = 0.08). However, after pericardiotomy, there was a significant fall in both RA elastance (54%, P < 0.04) and stiffness (39%, P < 0.04), and subsequent PA occlusion failed to induce a change in elastance (P > 0.19) or stiffness (P > 0.84). After pericardiotomy, RA elastance and stiffness fell dramatically, and the compensatory response of the right atrium to elevated RV afterload was lost. The ability of the right atrium to respond to changes in RV hemodynamics is highly dependent on pericardial integrity.