Benjamin Sohmer

Communication and team situation awareness in the OR: Implications for augmentative information display

Team Situation Awareness (TSA) is one of the critical factors in effective Operating Room (OR) teamwork and can impact patient safety and quality of care. While previous research showed a relationship between situation awareness, as measured by communication events, and team performance, the implications for developing technology to augment and facilitate TSA were not examined. This research aims to further study situation-related communications in the cardiac OR in order to uncover potential degradation in TSA which may lead to adverse events. The communication loop construct-the full cycle of information flow between the participants in the sequence-was used to assess susceptibility to breakdown. Previous research and the findings here suggest that communication loops that are open, non-directed, or with delayed closure, can be susceptible to information loss. These were quantitatively related to communication indicators of TSA such as questions, replies, and announcements. Taken together, both qualitative and quantitative analyses suggest that a high proportion of TSA-related communication (63%) can be characterized as susceptible to information loss. The findings were then used to derive requirements and design a TSA augmentative display. The design principles and potential benefits of such a display are outlined and discussed.

Minimally invasive coronary artery bypass grafting via a small thoracotomy versus off-pump: a case-matched study

OBJECTIVE The minimally invasive coronary artery bypass grafting (MICS CABG) operation performed via a small thoracotomy has not previously been examined in a direct comparison to sternotomy off-pump coronary artery bypass grafting (OPCAB). METHODS We matched, according to age, gender, left ventricular function, and median number of distal anastomoses, 150 patients who underwent MICS CABG via small left thoracotomy, and 150 patients who received sternotomy OPCAB. All operations were performed by the same surgeon. RESULTS There was no perioperative mortality (0/300). In the MICS CABG group, pump assistance was used in 28/150 (19%) patients, and conversion to sternotomy occurred in 10/150 (6.7%) patients. In the OPCAB group, conversion to on-pump occurred in 3/150 (2.0%) patients. There were four (2.7%) reoperations for bleeding and one (0.7%) for anastomotic revision in each group. The median hospital length of stay was 5 days for MICS CABG (average 5.4), and 6 days for OPCAB (average 7.2) (P=0.02). New-onset atrial fibrillation occurred in 35 (23%) MICS CABG patients and in 42 (28%) OPCAB patients (P=0.3). No wound infection occurred with MICS CABG versus six (4.0%) with OPCAB (P=0.03). A self-limiting left pleural effusion developed in 22 (15%) MICS CABG patients and in six (4.0%) OPCAB patients (P=0.002). The median time to return to full physical activity was 12 days in MICS CABG patients versus >5 weeks in OPCAB patients (P<0.001). CONCLUSIONS MICS CABG is a valuable alternative for patients in need of multivessel CABG. The operation appears at least as safe as OPCAB, and associated with shorter hospital length of stay, less wound infections, and faster postoperative recovery than OPCAB.

Results of the Minimally Invasive Coronary Artery Bypass Grafting Angiographic Patency Study.

OBJECTIVE Minimally invasive coronary artery bypass grafting is safe and widely applicable, and may be associated with fewer transfusions and infections, and better recovery than standard coronary artery bypass grafting. However, graft patency rates remain unknown. The Minimally Invasive Coronary Artery Bypass Grafting Patency Study prospectively evaluated angiographic graft patency 6 months after minimally invasive coronary artery bypass grafting. METHODS In this dual-center study, 91 patients were prospectively enrolled to undergo minimally invasive coronary artery bypass grafting via a 4- to 7-cm left thoracotomy approach. The left internal thoracic artery, the ascending aorta for proximal anastomoses, and all coronary targets were directly accessed without endoscopic or robotic assistance. The study primary outcome was graft patency at 6 months, using 64-slice computed tomography angiography. Secondary outcomes included conversions to sternotomy and major adverse cardiovascular events (Clinical Trial Registration Unique identifier: NCT01334866). RESULTS The mean age of patients was 64 ± 8 years, the mean ejection fraction was 51% ± 11%, and there were 10 female patients (11%) in the study. Surgeries were performed entirely off-pump in 68 patients (76%). Complete revascularization was achieved in all patients, and the median number of grafts was 3. There was no perioperative mortality, no conversion to sternotomy, and 2 reopenings for bleeding. Transfusion occurred in 24 patients (26%). The median length of hospital stay was 4 days, and all patients were followed to 6 months, with no mortality or major adverse cardiovascular events. Six-month computed tomography angiographic graft patency was 92% for all grafts and 100% for left internal thoracic artery grafts. CONCLUSIONS Minimally invasive coronary artery bypass grafting is safe, feasible, and associated with excellent outcomes and graft patency at 6 months post-surgery.

Modeling leaflet correction techniques in aortic valve repair: A finite element study

In aortic valve sparing surgery, cusp prolapse is a common cause of residual aortic insufficiency. To correct cusp pathology, native leaflets of the valve frequently require adjustment which can be performed using a variety of described correction techniques, such as central or commissural plication, or resuspension of the leaflet free margin. The practical question then arises of determining which surgical technique provides the best valve performance with the most physiologic coaptation. To answer this question, we created a new finite element model with the ability to simulate physiologic function in normal valves, and aortic insufficiency due to leaflet prolapse in asymmetric, diseased or sub-optimally repaired valves. The existing leaflet correction techniques were simulated in a controlled situation, and the performance of the repaired valve was quantified in terms of maximum leaflets stress, valve orifice area, valve opening and closing characteristics as well as total coaptation area in diastole. On the one hand, the existing leaflet correction techniques were shown not to adversely affect the dynamic properties of the repaired valves. On the other hand, leaflet resuspension appeared as the best technique compared to central or commissural leaflet plication. It was the only method able to achieve symmetric competence and fix an individual leaflet prolapse while simultaneously restoring normal values for mechanical stress, valve orifice area and coaptation area.

Handsewn Proximal Anastomoses Onto the Ascending Aorta Through a Small Left Thoracotomy During Minimally Invasive Multivessel Coronary Artery Bypass Grafting: A Stepwise Approach to Safety and Reproducibility

Minimally invasive coronary artery bypass grafting (MICS CABG) is a nonrobotic, nonthoracoscopic operation that achieves complete anatomical graft similarity with conventional CABG, while avoiding sternotomy and cardiac anoxia. We describe the stepwise approach to perform proximal anastomoses directly off the ascending aorta and also early results of this operation. All myocardial territories are accessed via a 4- to 6-cm left fifth intercostal thoracotomy. After takedown of the left internal thoracic artery, the ascending aorta is progressively brought into view by the following maneuvers: (1) administration of cardiac inotropes to minimize right ventricle filling, (2) increase in right lung positive end-expiratory pressures and tidal volumes, (3) placement of multilevel pericardial retractions, (4) leftward displacement of the ascending aorta with a gauze anterior to the superior vena cava, and (5) left posteroinferior displacement of the right ventricular outflow tract with an epicardial stabilizer. Handsewn proximal anastomoses can then be performed on the ascending aorta with a side-biting clamp. In the first 100 patients who underwent multivessel MICS CABG with proximal anastomoses directly off the aorta, the mean age was 62.6 ± 10.2 years, and median operative time was 3.5 hours. The mean number of grafts was 2.3 ± 0.5, and there were 3 conversions to open sternotomy. There were no preoperative deaths, 2 reoperations for bleeding, and 2 superficial wound infections. The median length of hospital stay was 4 days. MICS CABG is a safe alternative to conventional CABG, with excellent short-term results.

Subject-specific finite-element modeling of normal aortic valve biomechanics from 3D+t TEE images

In the past decades, developments in transesophageal echocardiography (TEE) have opened new horizons in reconstructive surgery of the aortic valve (AV), whereby corrections are made to normalize the geometry and function of the valve, and effectively treat leaks. To the best of our knowledge, we propose the first integrated framework to process subject-specific 3D+t TEE AV data, determine age-matched material properties for the aortic and leaflet tissues, build a finite element model of the unpressurized AV, and simulate the AV function throughout a cardiac cycle. For geometric reconstruction purposes, dedicated software was created to acquire the 3-D coordinates of 21 anatomical landmarks of the AV apparatus in a systematic fashion. Measurements from ten 3D+t TEE datasets of normal AVs were assessed for inter- and intra-observer variability. These tests demonstrated mean measurement errors well within the acceptable range. Simulation of a complete cardiac cycle was successful for all ten valves and validated the novel schemes introduced to evaluate age-matched material properties and iteratively scale the unpressurized dimensions of the valves such that, given the determined material properties, the dimensions measured in vivo closely matched those simulated in late diastole. The leaflet coaptation area, describing the quality of the sealing of the valve, was measured directly from the medical images and was also obtained from the simulations; both approaches correlated well. The mechanical stress values obtained from the simulations may be interpreted in a comparative sense whereby higher values are indicative of higher risk of tearing and/or development of calcification.

Unusual Cause of an Ejection Murmur: Myxoma in the Left Ventricular Outflow Tract

We present the case of a healthy, asymptomatic 50-year-old woman with a systolic ejection murmur who was found to have an obstructive left ventricular outflow tract mass. Transthoracic echocardiography revealed a large mobile mass attached to the basal anterior septum of the left ventricle. Surgical resection was performed and a benign left ventricular outflow tract myxoma was diagnosed. The patients postoperative course was unremarkable. We describe the clinical presentation and role of 2- and 3-dimensional transthoracic and transesophageal echocardiography in surgical management.

Mid-term Follow-up of Minimally Invasive Multivessel Coronary Artery Bypass Grafting: Is the Early Learning Phase Detrimental?

Objective Minimally invasive coronary artery bypass grafting (MICS CABG) through a small left thoracotomy is a novel technique for surgical coronary revascularization, which is increasingly being adopted around the world. This study aimed to describe the characteristics and mid-term outcomes of a series of MICS CABG to identify areas for improvement. Methods A prospective longitudinal study was performed on the 306 MICS CABG patients operated on by a single surgeon from 2005 to 2015. Minimally invasive coronary artery bypass grafting used a small left thoracotomy to enable coronary revascularization with a similar configuration to an open sternotomy technique, with left internal thoracic artery harvesting, and hand-sewn proximal radial/saphenous and distal anastomoses, under direct visualization. We compared patients who were operated on during the first and second halves of the series to ascertain the impact of a learning curve on outcomes. Results The mean ± SD age was 62 ± 9 years, 87% were male, and 23% had three-vessel disease. Off-pump coronary artery bypass was performed in 80%, and the median number of grafts was 2 (range 1–4). Sternotomy conversion occurred in 3.3%, reoperation for bleeding in 2%, and unplanned, emergency CPB conversion in 1%. Superficial thoracotomy infection, atrial fibrillation, and left-sided pleural effusion requiring drainage were encountered in 2%, 1%, and 1%, respectively. There were no perioperative stroke, myocardial infarction, or death. At a mean ± SD follow-up of 2.8 ± 2.5 years, 97.4% of patients were free from major adverse cardiac and cerebrovascular events. Between the first and latter half of the series, there was a decrease in the rate of conversion to sternotomy (5.2%–1.3%, P = 0.05) and in the mid-term need for repeat revascularization (11% vs 2.6%, P = 0.03). Overall repeat revascularization rate was 2.5% per year. The intensive care unit and hospital lengths of stay (1.6 ± 1.5 vs 1.4 ± 0.9, P = 0.2, and 6.1 ± 2.6 vs 5.6 ± 1.8, P = 0.4) were not statistically different. Conclusions Minimally invasive coronary artery bypass grafting can be safely initiated as a minimally invasive, multivessel alternative to open surgical coronary revascularization, with excellent mid-term results. Learning phase effects were not observed with regard to overall procedural safety, but rather in terms of improved freedom from conversion to sternotomy and from repeat revascularization.

Aortic root geometry in bicuspid aortic insufficiency versus stenosis: implications for valve repair

OBJECTIVES The contribution of aortic annular and root disease in bicuspid aortic valve (BAV) insufficiency remains unclear. We compared aortic root geometry between BAV stenosis and aortic insufficiency (AI), before and after repair. METHODS Patients presenting for surgery for BAV insufficiency (n = 58) were compared with patients with BAV stenosis (n = 58). Clinical and transoesophageal echocardiographic data were collected, including end-diastolic diameters of the ventriculo-aortic junction (VAJ), aortic root, sinotubular junction (STJ) and ascending aorta (AA). RESULTS AI patients were younger and more likely to be male compared with aortic stenosis (AS) patients. VAJ, aortic root and STJ diameters were significantly larger in AI compared with AS patients (30 ± 0.5 vs 25 ± 0.4 mm, P < 0.001; 41 ± 0.8 vs 34 ± 0.6 mm, P < 0.001; 36 ± 0.9 vs 30 ± 0.6 mm, P < 0.001, respectively). Following multivariable adjustment for age, sex, body surface area and ascending aortic diameter, these diameters remained larger in AI patients with a mean difference of 3, 6 and 4 mm, respectively (all P < 0.001). Mean AA diameter in the AI group was similar to the AS group (37 ± 1.0 vs 34 ± 0.8 mm, P = 0.06). Forty (69%) AI patients had BAV repair with a mean reduction in VAJ and STJ diameters of 5 and 9 mm compared with prerepair (P < 0.0001). CONCLUSIONS Despite the absence of aortic aneurysms, aortic annulus and root dimensions are significantly larger in patients with BAV insufficiency compared with stenosis. Alterations in aortic root geometry contribute to the pathophysiology of BAV insufficiency and require correction for a successful repair.

Aortic Valve Cusp Coaptation Surface Area Using 3-Dimensional Transesophageal Echocardiography Correlates with Severity of Aortic Valve Insufficiency

OBJECTIVE The aim of this study was to test both in humans and using finite element (FE) aortic valve (AV) models whether the coaptation surface area (CoapSA) correlates with aortic insufficiency (AI) severity due to dilated aortic roots to determine the validity and utility of 3-dimensional transesophageal echocardiographic-measured CoapSA. DESIGN Two-pronged, clinical and computational approach. SETTING Single university hospital. PARTICIPANTS The study comprised 10 patients with known AI and 98 FE simulations of increasingly dilated human aortic roots. INTERVENTIONS The CoapSA was calculated using intraoperative 3-dimensional transesophageal echocardiography data of patients with isolated AI and compared with established quantifiers of AI. In addition, the CoapSA and effective regurgitant orifice area (EROA) were determined using FE simulations. MEASUREMENTS AND MAIN RESULTS In the 10 AI patients, regurgitant fraction (RF) increased with EROA (R2 = 0.77, p = 0.0008); CoapSA decreased with RF (R2 = 0.72, p = 0.0020); CoapSA decreased with EROA (R2 = 0.71, p = 0.0021); and normalized CoapSA (CoapSA / [Ventriculo-Aortic Junction × Sinotubular Junction]) decreased with EROA (R2 = 0.60, p = 0.0088). In the 98 FE simulations, normalized CoapSA decreased with EROA (R2 = 0.50, p = 0.0001). CONCLUSIONS In both human and FE AV models, CoapSA was observed to be inversely correlated with AI severity, EROA, and RF, thereby supporting the validity and utility of 3D TEE-measured CoapSA. A clinical implication is the expectation that high values of CoapSA, measured intraoperatively after AV repairs, would correlate with better long-term outcomes of those repairs.