Bayesian networks identify determinants of outcomes following cardiac surgery in a UK population.

BACKGROUND: Traditional risk stratification tools do not describe the complex principle determinant relationships that exist amongst pre-operative and peri-operative factors and their influence on cardiac surgical outcomes. This paper reports on the use of Bayesian networks to investigate such outcomes. METHODS: Data were prospectively collected from 4776 adult patients undergoing cardiac surgery at a single UK institute between April 2012 and May 2019. Machine learning techniques were used to construct Bayesian networks for four key short-term outcomes including death, stroke and renal failure. RESULTS: Duration of operation was the most important determinant of death irrespective of EuroSCORE. Duration of cardiopulmonary bypass was the most important determinant of re-operation for bleeding. EuroSCORE was predictive of new renal replacement therapy but not mortality. CONCLUSIONS: Machine-learning algorithms have allowed us to analyse the significance of dynamic processes that occur between pre-operative and peri-operative elements. Length of procedure and duration of cardiopulmonary bypass predicted mortality and morbidity in patients undergoing cardiac surgery in the UK. Bayesian networks can be used to explore potential principle determinant mechanisms underlying outcomes and be used to help develop future risk models.

Revascularisation strategies in patients with significant left main coronary disease during the COVID-19 pandemic.

BACKGROUND: There are limited data on the impact of the COVID-19 pandemic on left main (LM) coronary revascularisation activity, choice of revascularisation strategy, and post-procedural outcomes. METHODS: All patients with LM disease (≥50% stenosis) undergoing coronary revascularisation in England between January 1, 2017 and August 19, 2020 were included (n = 22,235), stratified by time-period (pre-COVID: 01/01/2017-29/2/2020; COVID: 1/3/2020-19/8/2020) and revascularisation strategy (percutaneous coronary intervention (PCI) vs. coronary artery bypass grafting (CABG). Logistic regression models were performed to examine odds ratio (OR) of 1) receipt of CABG (vs. PCI) and 2) in-hospital and 30-day postprocedural mortality, in the COVID-19 period (vs. pre-COVID). RESULTS: There was a decline of 1,354 LM revascularisation procedures between March 1, 2020 and July 31, 2020 compared with previous years' (2017-2019) averages (-48.8%). An increased utilization of PCI over CABG was observed in the COVID period (receipt of CABG vs. PCI: OR 0.46 [0.39, 0.53] compared with 2017), consistent across all age groups. No difference in adjusted in-hospital or 30-day mortality was observed between pre-COVID and COVID periods for both PCI (odds ratio (OR): 0.72 [0.51. 1.02] and 0.83 [0.62, 1.11], respectively) and CABG (OR 0.98 [0.45, 2.14] and 1.51 [0.77, 2.98], respectively) groups. CONCLUSION: LM revascularisation activity has significantly declined during the COVID period, with a shift towards PCI as the preferred strategy. Postprocedural mortality within each revascularisation group was similar in the pre-COVID and COVID periods, reflecting maintenance in quality of outcomes during the pandemic. Future measures are required to safely restore LM revascularisation activity to pre-COVID levels.

A customized technique for confluent aortic annular and selective sinus of Valsalva endocarditis.

We describe a novel technical modification for reoperative aortic valve replacement in destructive recurrent prosthetic aortic valve endocarditis. We encountered complex anatomy in a previously operated aortic root wherein the aortic annulus and the right coronary sinus of Valsalva were destroyed. This precluded secure suture placement. We modified a composite mechanical Valsalva conduit to create a separate sinus of Valsalva left in continuity with the mechanical valve. This approach allowed us to exclude the infected right sinus of Valsalva and the corresponding aortic annulus.

Early life threatening constrictive pericarditis following off-pump CABG.

We present a unique case of aggressive symptomatic constrictive pericarditis within one month following off pump coronary artery bypass grafting surgery. The patient had a medical history of Hodgkin's lymphoma treated with radiotherapy and chemotherapy 20 years ago. Investigations confirmed constrictive pericardium with patent grafts and good biventricular function. Pericardiectomy was successful with remarkable recovery of symptoms.

Delayed surgical strategy for type A aortic dissection associated with acute hepatitis C cryoglobulinaemia.

An aortic dissection is a condition resulting from a tunica intima tear of the aortic wall creating a 'false lumen'. An acute Stanford type A (involves the aortic arch and/or ascending aorta) aortic dissection requires emergency surgical repair. To our knowledge, we report the first case in the literature where the treatment for an acute type A aortic dissection was intentionally delayed. This was decided following a multidisciplinary team discussion where it was agreed that the patient's active hepatitis C infection should be treated prior to surgery. The patient re-presented to the hospital 4 months later with acute dyspnoea and orthopnoea where he was diagnosed with an acute-on-chronic type A aortic dissection with trachea compression. This was successfully treated with emergency surgery. However, the patient suffered residual dyspnoea, likely due to phrenic nerve injury demonstrating the impact of untreated aortic arch distension on the neighbouring trachea and phrenic nerve.

Anterior leaflet replacement and reconstruction with Admedus Cardiocel™ decellularized pericardial patch in tricuspid valve endocarditis.

We present the case of a 28 year-old lady with a history of intravenous drug use who presented to our institution with symptomatic right heart failure secondary to tricuspid valve regurgitation. She presented with infective endocarditis leading to dyspnoea and peripheral oedema secondary to torrential tricuspid regurgitation. Transthoracic echocardiography confirmed right ventricular dysfunction and congestive hepatomegaly. Intra-operatively findings an infected and destroyed anterior leaflet of the tricuspid valve with posterior leaflet prolapse was found to cause severe tricuspid regurgitation. She had complex tricuspid valve reconstruction using anterior leaflet reconstruction using Admedus Cardiocel™ patch, posterior leaflet prolapse correction and commissural reduction with a McGoon imbrication and annuloplasty ring to stabilize the repair. This case demonstrates the importance of reconstructive tricuspid valve surgery in the setting of infective endocarditis. Furthermore, this case demonstrates the possibility of anterior leaflet excision and reconstruction with an excellent durable functional result.

Indirect Impact of the COVID-19 Pandemic on Activity and Outcomes of Transcatheter and Surgical Treatment of Aortic Stenosis in England.

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A comparison of transit-time flowmetry and intraoperative fluorescence imaging for assessing coronary artery bypass graft patency.

BACKGROUND: Intraoperative graft patency assessment during coronary artery bypass grafting enables detection and immediate correction of graft failure. Currently transit-time flowmetry is used to assess graft patency on the basis of mean graft flow and derived values, such as the pulsatility index. Intraoperative fluorescence imaging, based on the fluorescence of indocyanine green dye, provides direct visual images to confirm graft patency. METHODS: We performed a prospective observational study to assess intraoperative graft patency in patients undergoing coronary artery bypass grafting, by using an intraoperative fluorescence imaging system (SPY) and transit-time flowmetry (BF 2004). Poor flow with the intraoperative fluorescence imaging system was defined if there was an absence of fluorescence or if it did not appear within 15 seconds in the graft. A persistent mean graft flow value less than 5 mL/min and a pulsatility index greater than 5 with transit-time flowmetry were considered unacceptable and prompted graft revision. RESULTS: We assessed the intraoperative patency of 266 grafts in 100 coronary artery bypass grafting patients. Intraoperative fluorescence imaging and transit-time flowmetry confirmed adequate flow in 241 (91%) grafts in 75 patients (75%). Transient poor flow was detected with both intraoperative fluorescence imaging and transit-time flowmetry in 7 (2.6%) grafts in 7 (7%) patients. This subsequently proved to be adequate on repeat testing and hence did not necessitate graft revision. Both intraoperative fluorescence imaging and transit-time flowmetry confirmed persistent poor flow in 8 (3%) grafts in 8 (8%) patients that necessitated graft revision. However, in a further 10 (3.8%) grafts in 10 (10%) patients, transit-time flowmetry indicated persistently poor flows on the basis of mean graft flow and pulsatility index values, whereas the intraoperative fluorescence imaging system demonstrated satisfactory flow. These grafts were not revised. CONCLUSIONS: In most patients, both intraoperative fluorescence imaging and transit-time flowmetry are useful to confirm intraoperative graft patency. However, in a small proportion of patients (10%), graft patency assessment with transit-time flowmetry alone might prompt unnecessary graft revision.

Solid and gaseous cerebral microembolization during off-pump, on-pump, and open cardiac surgery procedures.

BACKGROUND: Neurocognitive dysfunction remains a limitation of cardiac surgery with cardiopulmonary bypass. Intraoperative cerebral microembolization is believed to be one of the most important etiologic factors. Using a new generation of transcranial Doppler ultrasonography, we compared the number and nature of intraoperative microemboli in patients undergoing on-pump and off-pump cardiac surgery procedures. METHODS: Bilateral continuous transcranial Doppler monitoring of the middle cerebral arteries was performed in 45 patients (15 off-pump coronary artery bypass grafting, 15 on-pump coronary artery bypass grafting, and 15 open cardiac procedures). All recordings were performed using a multi-range, multifrequency system to allow both measurement of the number and discrimination of the nature of microemboli in the 3 different groups. RESULTS: The median number (interquartile range) of microemboli in the off-pump coronary artery bypass grafting, on-pump coronary artery bypass grafting, and open procedure groups were 40 (28-80), 275 (199-472), and 860 (393-1321), respectively (P <.01). Twelve percent of microemboli in the off-pump coronary artery bypass grafting group were solid compared with 28% and 22% in the on-pump coronary artery bypass grafting and open procedure groups, respectively (P <.05). In the on-pump groups, 24% of microemboli occurred during cardiopulmonary bypass, and 56% occurred during aortic manipulation (cannulation, decannulation, application, and removal of crossclamp or sideclamp). CONCLUSIONS: Cerebral microembolization is significantly reduced with avoidance of cardiopulmonary bypass. The majority of microemboli occurring during cardiac surgery are gaseous, with a higher proportion of solid microemboli in the on-pump group, and may have a different significance for cerebral injury than solid microemboli. The ability to reliably discriminate gas and solid microemboli may have an important role in the implementation of neuroprotective strategies.

Does off-pump total arterial grafting increase the incidence of intraoperative graft failure?

BACKGROUND: Early graft failure is a common cause of cardiac mortality and morbidity after coronary artery bypass grafting, but there is little information on its natural incidence. Furthermore, there is particular concern about graft patency in off-pump coronary artery bypass grafting and total arterial grafting. METHODS: We performed a prospective observational study to assess intraoperative graft patency in patients undergoing off-pump and on-pump coronary artery bypass grafting, who also underwent total arterial grafting. We used an intraoperative imaging system, SPY (Novadaq Technologies Inc), based on the fluorescent properties of indocyanine green dye. RESULTS: We assessed the intraoperative graft patency of 533 conduits in 200 patients. The mean number of grafts was 2.7 per patient. Of these patients, 155 (78%) had off-pump coronary artery bypass grafting, and 45 (22%) had on-pump coronary artery bypass grafting. Overall, 161 (80%) had total arterial grafting, with composite arterial grafting performed in 120 (60%) patients. Fluorescence, confirming graft patency, was observed in all but 8 (1.5%) conduits in 8 (4%) patients, necessitating graft revision. Six (3.9%) and 2 (4.4%) of these patients, respectively, had off-pump coronary artery bypass grafting and on-pump coronary artery bypass grafting. CONCLUSION: Intraoperative fluorescence imaging demonstrated a low (1.5%) but well-defined incidence of intraoperative graft failure, which affects around 4% of patients. This emphasizes the need for routine assessment of graft patency. Intraoperative fluorescence imaging permits detection and revision of failed grafts in the operating room. We found no difference in the incidence of failed grafts when comparing on-pump and off-pump total arterial grafting.

Accessory spleniculi in the right hemithorax.

Accessory spleniculi are present in the thoracic cavity without a history of trauma due to anomalies in the development of spleen. We report the case of a 62-year-old woman with hereditary spherocytosis and previous splenectomy with an incidental mass on a chest radiograph and an indeterminate diagnosis on needle biopsy. The probable sequence of embryological events that may explain the anatomic presence of splenic tissue in the thorax is discussed.

Preliminary experience with a novel intraoperative fluorescence imaging technique to evaluate the patency of bypass grafts in total arterial revascularization.

BACKGROUND: Early graft failure is a common cause of cardiac morbidity and mortality after coronary artery bypass grafting (CABG), and there is particular concern about graft patency in off-pump CABG. We describe our preliminary experience with a novel imaging technique (the SPY system), based on fluorescence of Indocyanine Green when exposed to near infrared light, for the intraoperative assessment of coronary graft patency. METHODS: Graft patency was assessed in patients undergoing off-pump and on-pump total arterial revascularization. The imaging technique requires injection of a 1-mL bolus of Indocyanine Green into the central venous line, followed by imaging with the SPY system. RESULTS: We assessed intraoperative graft patency in 213 conduits in 84 patients (mean, 2.54 grafts per patient), of which, 65 (77%) were done off-pump. It took approximately 3 minutes to image each graft. Skeletonized conduits provided better visualization than pedicled ones. Fluorescence, confirming graft patency, was observed in all but four (1.9%) conduits in 4 (5%) patients. In these latter cases, graft revision was necessitated. CONCLUSIONS: Fluorescence imaging of coronary grafts using the SPY is a uniquely simple, safe, noninvasive, and reproducible technique for intraoperative confirmation of graft patency. In 4 patients, it necessitated revision of the initial intraoperative procedure. Quantification of graft flow would enhance the value of the system.

Digital tools to facilitate intraoperative coronary artery bypass graft patency assessment.

Intraoperative graft failure is an important cause of cardiac mortality and morbidity. Hence, verification of graft patency should be one of the most important aspects of coronary artery bypass grafting. Although several techniques have been advocated to assess intraoperative graft patency, there is no unanimously accepted method. Intraoperative fluorescence imaging is a novel technique based on the fluorescence of indocyanine green dye, which provides real-time visual images of graft flow in the operating room. Transit-time flowmetry is based on the ultrasound principle and provides mean graft flow and derived values such as pulsatility index. This article describes the usefulness and limitations of various techniques in general and summarizes the current knowledge with the use of these two techniques in the setting of intraoperative coronary artery bypass graft patency assessment.

Minimally invasive direct coronary artery bypass as a primary strategy for reoperative myocardial revascularization.

OBJECTIVE: : Conventional reoperative coronary artery bypass grafting is associated with risk of sternal re-entry, injury to patent grafts, and embolization from diseased grafts. Sternal sparing minimally invasive direct coronary artery bypass (MIDCAB) avoids such risks in cases where it is technically feasible. We sought to examine in-hospital outcomes of reoperative MIDCAB surgery. METHODS: : We recorded prospective standardized data from the New York Cardiac Surgical Reporting System database of 369 reoperative MIDCAB cases from 1996 to 2006 and compared with 822 primary MIDCAB patients in the same time period. We compared the preoperative risk profile and postoperative in-hospital outcomes and length of stay for both groups. RESULTS: : There was a significantly higher risk profile typical of the reoperative patient population (P < 0.001 for stroke, peripheral/cerebrovascular disease, extensive aortic calcification, renal failure, and left ventricular ejection fraction <40%) compared with the primary MIDCAB group. Despite this fact, there was no difference in the in-hospital outcomes and length of hospital stay between the two groups. CONCLUSIONS: : Reoperative MIDCAB provides targeted coronary revascularization and avoids hazards of sternal re-entry, graft injury and manipulation, and deleterious effects of cardiopulmonary bypass. This hastens recovery and provides excellent early outcomes equivalent to primary MIDCAB procedures.