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Acute kidney injury (AKI) is common after cardiac surgery. We quantified the mortality and costs of varying degrees of AKI using a population-based cohort in Alberta, Canada.A cohort of patients undergoing cardiac surgery from 2004 to 2009 was assembled from linked Alberta administrative databases. AKI was classified by Kidney Disease Improving Global Outcomes stages of severity. Our outcomes were in-hospital mortality, length of stay, and costs; among survivors, we also examined mortality and costs at 365 days. Estimates were adjusted for demographic characteristics, comorbidities, and other covariates.Ten thousand one hundred seventy participants were included, of whom 9771 patients were discharged to community. Overall in-hospital mortality, costs, and length of stay were 4%, 7 days, and Can $34,000, respectively. Postcardiac surgery, AKI occurred in 25%. Compared with those without AKI, AKI was independently associated with increased in-hospital mortality across severity categories, with the highest risk (adjusted odds ratio, 37.1; 95% confidence interval, 26.3-52.1; P .001) in patients who required acute dialysis. AKI severity was associated with increased hospital days and costs, with costs ranging from 1.21 for stage 1 AKI (95% confidence interval, 1.17-1.23) to 2.74 for acute dialysis (95% confidence interval, 2.49-3.00) (P .001) times higher than in patients without AKI, after covariate adjustment. Postdischarge to 365 days, patients with AKI continued to experience increased costs up to 1.35-fold, and patients who required dialysis acutely continued to experience a 2.86-fold increased mortality.AKI remains an important indicator of mortality and health care costs postcardiac surgery.

OBJECTIVES Despite society guideline recommendations, intraoperative high-frequency ultrasound (HFUS) and transit-time flow measurement (TTFM) use in coronary artery bypass grafting (CABG) has not been widely adopted worldwide. This retrospective review of the REQUEST (REgistry for QUality assESsmenT with Ultrasound Imaging and TTFM in Cardiac Bypass Surgery) study assesses the impact of protocolled high-frequency ultrasound/TTFM use in specific technical circumstances of CABG. METHODS Three REQUEST study sub-analyses were examined: (i) For off-pump (OPCAB) versus on-pump (ONCAB) procedures: strategy changes from preoperative plans for the aorta, conduits, coronary targets and graft revisions; and for all REQUEST patients, revision rates in: (ii) arterial versus venous grafts; and (iii) grafts to different cardiac territories. RESULTS Four hundred and two (39.6%) of 1016 patients undergoing elective isolated CABG for multivessel disease underwent OPCAB procedures. Compared to ONCAB, OPCAB patients experienced more strategy changes regarding the aorta [14.7% vs 3.4%; odds ratios (OR) = 4.03; confidence interval (CI) = 2.32–7.20], less regarding conduits (0.2% vs 2.8%; OR = 0.09; CI = 0.01–0.56), with no differences in coronary target changes or graft revisions (4.1% vs 3.5%; OR = 1.19; CI = 0.78–1.81). In all REQUEST patients, revisions were more common for arterial versus venous grafts (4.7% vs 2.4%; OR = 2.05; CI = 1.29–3.37), and inferior versus anterior (5.1% vs 2.9%; OR = 1.77; CI = 1.08–2.89) and lateral (5.1% vs 2.8%; OR = 1.83; CI = 1.04–3.27) territory grafts. CONCLUSIONS High-frequency ultrasound/TTFM use differentially impacts strategy changes and graft revision rates in different technical circumstances of CABG. Notably, patients undergoing OPCAB experienced 4 times more changes related to the ascending aorta than ONCAB patients. These findings may indicate where intraoperative assessment is most usefully applied. Clinical trial registration number ClinicalTrials.gov: NCT02385344

OBJECTIVES Factors such as more diffuse atherosclerosis, plaque instability and accelerated vascular calcification in patients with chronic and end-stage renal disease (ESRD) can potentially present intraoperative challenges in coronary artery bypass grafting (CABG) procedures. We evaluated whether patients with chronic and ESRD experienced more surgical strategy changes and/or graft revisions than patients with normal renal function when undergoing CABG procedures according to a protocol for intraoperative high-frequency ultrasound and transit-time flow measurement (TTFM). METHODS Outcomes of CABG for patients with chronic and ESRD and patients with normal renal function enrolled in the multicentre prospective REQUEST (REgistry for QUality assESsmenT with Ultrasound Imaging and TTFM in Cardiac Bypass Surgery) study were compared retrospectively. The primary end point was frequency of intraoperative surgical strategy changes. The secondary end point was post-protamine TTFM parameters. RESULTS There were 95 patients with chronic and ESRD and 921 patients with normal renal function. Patients with chronic and ESRD undergoing CABG according to a protocol for intraoperative high-frequency ultrasound and TTFM had a higher rate of strategy changes overall [33.7% vs 24.3%; odds ratio (OR) = 1.58; 95% confidence interval (CI) = 1.01–2.48; P = 0.047] and greater revisions per graft (7.0% vs 3.4%; odds ratio = 2.14; 95% CI = 1.17–3.71; P = 0.008) compared to patients with normal renal function. Final post-protamine graft TTFM parameters were comparable between cohorts. CONCLUSIONS Patients with chronic and ESRD undergoing CABG procedures with high-frequency ultrasound and TTFM experience more surgical strategy changes than patients with normal renal function while achieving comparable graft flow. Clinical trial registration number ClinicalTrials.gov NCT02385344

Intraoperative bypass graft evaluation for coronary artery bypass graft surgery has now been recommended in three consecutive European guidelines for myocardial revascularization in 2010, 2014, and 2018. The two main modalities consist of transit-time flow measurement which assesses function of grafts and epicardial ultrasound to assess the anatomy of the anastomosis. Functional and morphological assessment are generally considered complementary, although transit-time flow measurement is the most commonly used. Transit-time flow measurement alone may have ambiguous values in 5–15% of grafts and this can lead to unnecessary graft revision. The addition of epicardial ultrasound aids interpretation of intraoperative graft assessment by allowing visualization of the anastomosis and correction of technical errors that, intuitively, will lead to improved patient outcomes.

Summary Despite there being numerous studies of intraoperative graft flow assessment by transit-time flow measurement (TTFM) on outcomes after coronary artery bypass grafting (CABG), the adoption of contemporary TTFM is low. Therefore, on 31 January 2018, a systematic literature search was performed to identify articles that reported (i) the amount of grafts classified as abnormal or which were revised or (ii) an association between TTFM and outcomes during follow-up. Random-effects models were used to create pooled estimates with 95% confidence intervals (CI) of (i) the rate of graft revision per patient, (ii) the rate of graft revision per graft and (iii) the rate of graft revision among grafts deemed abnormal based on TTFM parameters. The search yielded 242 articles, and 66 original articles were included in the systematic review. Of those articles, 35 studies reported on abnormal grafts or graft revisions (8943 patients, 15 673 grafts) and were included in the meta-analysis. In 4.3% of patients (95% CI 3.3–5.7%, I2 = 73.9) a revision was required and 2.0% of grafts (95% CI 1.5–2.5%; I2 = 66.0) were revised. The pooled rate of graft revisions among abnormal grafts was 25.1% (95% CI 15.5–37.9%; I2 = 80.2). Studies reported sensitivity ranging from 0.250 to 0.457 and the specificity from 0.939 to 0.984. Reported negative predictive values ranged from 0.719 to 0.980 and reported positive predictive values ranged from 0.100 to 0.840. This systematic review and meta-analysis showed that TTFM could improve CABG procedures. However, due to heterogeneous data, drawing uniform conclusions appeared challenging. Future studies should focus on determining the optimal use of TTFM and assessing its diagnostic accuracy.

BACKGROUND: Endothelial dysfunction is an early pathogenic event in the progression of cardiovascular disease in patients with type 2 diabetes (T2D). Endothelial KCa2.3 and KCa3.1 K(+) channels are important regulators of arterial diameter, and we thus hypothesized that SKA-31, a small molecule activator of KCa2.3 and KCa3.1, would positively influence agonist-evoked dilation in myogenically active resistance arteries in T2D. METHODOLOGY: Arterial pressure myography was utilized to investigate endothelium-dependent vasodilation in isolated cremaster skeletal muscle resistance arteries from 22–24 week old T2D Goto-Kakizaki rats, age-matched Wistar controls, and small human intra-thoracic resistance arteries from T2D subjects. Agonist stimulated changes in cytosolic free Ca(2+) in acutely isolated, single endothelial cells from Wistar and T2D Goto-Kakizaki cremaster and cerebral arteries were examined using Fura-2 fluorescence imaging. MAIN FINDINGS: Endothelium-dependent vasodilation in response to acetylcholine (ACh) or bradykinin (BK) was significantly impaired in isolated cremaster arteries from T2D Goto-Kakizaki rats compared with Wistar controls, and similar results were observed in human intra-thoracic arteries. In contrast, inhibition of myogenic tone by sodium nitroprusside, a direct smooth muscle relaxant, was unaltered in both rat and human T2D arteries. Treatment with a threshold concentration of SKA-31 (0.3 μM) significantly enhanced vasodilatory responses to ACh and BK in arteries from T2D Goto-Kakizaki rats and human subjects, whereas only modest effects were observed in non-diabetic arteries of both species. Mechanistically, SKA-31 enhancement of evoked dilation was independent of vascular NO synthase and COX activities. Remarkably, SKA-31 treatment improved agonist-stimulated Ca(2+) elevation in acutely isolated endothelial cells from T2D Goto-Kakizaki cremaster and cerebral arteries, but not from Wistar control vessels. In contrast, SKA-31 treatment did not affect intracellular Ca(2+) release by the sarco/endoplasmic reticulum Ca(2+)-ATPase (SERCA) inhibitor cyclopiazonic acid. CONCLUSIONS: Collectively, our data demonstrate that KCa channel modulation can acutely restore endothelium-dependent vasodilatory responses in T2D resistance arteries from rats and humans, which appears to involve improved endothelial Ca(2+) mobilization.

The "Achilles heel" of coronary artery bypass graft (CABG) surgery is graft patency. While long-term patency is determined by the type of conduit and the progression of graft and native vessel disease, short-term patency is affected by intra-operative technical issues. Transit-time flow measurements and epicardial ultrasound have been shown to accurately assess intra-operative graft patency. This review will examine the evidence to support the premise that intra-operative graft assessment is essential in determining graft patency and should be the standard of care when performing CABG surgery.

Objective To assess the prevalence and clinical significance of incidental findings identified during computed tomography imaging of coronary artery bypass grafts. Results This prospective study includes 144 patients undergoing coronary graft patency assessment using computed tomography. Incidental findings were classified as significant if they were considered to need an immediate action or treatment, short-term work-up or follow-up, or minor. A total of 211 incidental findings were present in 109 (75.7%) patients. Seventy-one incidental findings (33.6%) were cardiac and 140 (66.4%) were extracardiac. Most common cardiac incidental findings were atrial dilatation [39 patients, 48 incidental findings (67.6%)] and aortic valve calcifications (7 patients, 9.9%). Among the 140 extracardiac incidental findings, the most common were lung nodules (51 patients, 54 nodules, 38.6%), and emphysema (21 patients, 15%). Thirty-six (25.7%) extracardiac incidental findings were significant and notably, 23 (63.9%) were lung nodules. Follow-up was recommended in 37 cases, among which all patients with significant lung nodules (23 patients, 62.2%). In conclusion, most common computed tomography incidental findings in patients with coronary grafts were lung nodules and emphysema. Electronic supplementary material The online version of this article (10.1186/s13104-018-3168-1) contains supplementary material, which is available to authorized users.

Purpose of review The coronary artery bypass graft (CABG) operation is one of the few remaining operations/interventions on diseased arteries that are not routinely verified during or immediately after the procedure. This review answers the 'how', 'when' and 'why' of intraoperative CABG assessment. Recent findings More recent than new literature on this topic, is the increased interest in quality assurance of CABG. This is most likely due to reports in the last 5 years suggesting CABG superiority to percutaneous coronary intervention (PCI) for improved mid-term and long-term outcomes; for example, for patients with diabetes mellitus (Freedom Trial by Farkouh in 2012), and for patients with SYNTAX score ≥ 33 (SYNTAX Trial by Mohr in 2013). Possibly CABG is re-emerging from the era-of-better-and-better-stents and is now deemed worthy of improvement. Summary In order to fully compliment PCI, the operative major adverse cardiac event rate of CABG must rival that of PCI. In order to reduce technical errors, it is best practice to perform intra-operative assessment of bypasses, especially since we have the tools.

Objectives We evaluated the influence of transit-time flow measurement with epicardial and epiaortic high-frequency ultrasound in patients undergoing coronary artery bypass grafting procedure. Methods The Registry for Quality Assessment with Ultrasound Imaging and Transit-time Flow Measurement in Cardiac Bypass Surgery study is a multicenter, prospective study among 7 international centers performing coronary artery bypass grafting procedures. The primary end point was any change in the planned surgical procedure. Major secondary end points consisted of the rate and reason for surgical changes related to the aorta, in situ conduits, coronary targets, and completed grafts, and the rate of in-hospital mortality and major morbidity. Results Between April 2015 and December 2017, 1046 patients were enrolled. Of those, 1016 were included in the final analyses. Mean age was 65.9 years, 14.0% were women, and diabetes was present in 39.6%. Off-pump procedures were performed in 39.6% and bilateral internal thoracic arteries in 30.5%. The primary end point occurred in 25.2% of patients (n = 256) and in 77% (197 out of 256) this was based on transit-time flow measurement and/or high-frequency ultrasound. Surgical changes were related to the aorta in 9.9%, to in situ conduits in 2.7%, and the coronary targets in 22.6%. Graft revision occurred in 7.8%, including revisions of the proximal and/or distal anastomosis in 6.6%. In-hospital adverse event rates were 0.6% for mortality, 1.0% for cerebrovascular events, and 0.3% for myocardial infarction. Conclusions Surgical changes related to the aorta, conduits, coronary targets, and anastomosis were made in 25% of patients. This was associated with low operative mortality and low major morbidity. Transit-time flow measurement and high-frequency ultrasound may improve the quality, safety, and efficacy of coronary artery bypass grafting procedures and should be considered as a routine procedural aspect.

Coronary artery disease is the leading cause of morbidity and mortality even in the elderly population. Treatment opportunities in the elderly population are often underappreciated. Revascularization procedures (coronary artery bypass graft surgery and percutaneous coronary intervention) can be associated with important benefits in symptom control, quality of life, and long-term mortality, at an upfront cost of an increased risk of in-hospital mortality and morbidity. Risk models to assess periprocedural risk are useful. The best models would balance unique aspects of risk with the very real potential benefit of revascularization. Current models fall short in this regard. Frailty, a clinical syndrome of vulnerability, is present in 25%-50% of cardiac patients, and is associated with increased morbidity and mortality. The addition of frailty can improve the discrimination of risk models. Elderly patients commonly consider quality of life to have greater importance than mortality outcomes. Furthermore, hospital admission is associated with a reduction in mobilization, loss of muscle strength, and worsening frailty, and interferes with a fundamental value in the elderly: the maintenance of independence. Therefore, an understanding of frailty, quality of life, and other unique aspects of risk, as well as individual patient goals, can assist in further defining prognosis and refine decision-making in this important and vulnerable population.

Background Endothelial dysfunction is an early pathogenic event in the progression of cardiovascular disease in patients with Type 2 Diabetes (T2D). Endothelial KCa2.3 and KCa3.1 K+ channels are important regulators of arterial diameter, and we thus hypothesized that SKA-31, a small molecule activator of KCa2.3 and KCa3.1, would positively influence agonist-evoked dilation in myogenically active resistance arteries in T2D. Methodology Arterial pressure myography was utilized to investigate endothelium-dependent vasodilation in isolated cremaster skeletal muscle resistance arteries from 22 to 24 week old T2D Goto-Kakizaki rats, age-matched Wistar controls, and small human intra-thoracic resistance arteries from T2D subjects. Agonist stimulated changes in cytosolic free Ca2+ in acutely isolated, single endothelial cells from Wistar and T2D Goto-Kakizaki cremaster and cerebral arteries were examined using Fura-2 fluorescence imaging. Main findings Endothelium-dependent vasodilation in response to acetylcholine (ACh) or bradykinin (BK) was significantly impaired in isolated cremaster arteries from T2D Goto-Kakizaki rats compared with Wistar controls, and similar results were observed in human intra-thoracic arteries. In contrast, inhibition of myogenic tone by sodium nitroprusside, a direct smooth muscle relaxant, was unaltered in both rat and human T2D arteries. Treatment with a threshold concentration of SKA-31 (0.3 μM) significantly enhanced vasodilatory responses to ACh and BK in arteries from T2D Goto-Kakizaki rats and human subjects, whereas only modest effects were observed in non-diabetic arteries of both species. Mechanistically, SKA-31 enhancement of evoked dilation was independent of vascular NO synthase and COX activities. Remarkably, SKA-31 treatment improved agonist-stimulated Ca2+ elevation in acutely isolated endothelial cells from T2D Goto-Kakizaki cremaster and cerebral arteries, but not from Wistar control vessels. In contrast, SKA-31 treatment did not affect intracellular Ca2+ release by the sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) inhibitor cyclopiazonic acid. Conclusions Collectively, our data demonstrate that KCa channel modulation can acutely restore endothelium-dependent vasodilatory responses in T2D resistance arteries from rats and humans, which appears to involve improved endothelial Ca2+ mobilization.

In humans and other mammals, isocapnic hypoxia sustained for 20–60 min exhibits a biphasic ventilation pattern: initial increase followed by a significant ventilatory decline (“roll-off”) to a lesser intermediate plateau. During sustained hypoxia, the mechanical action and activity of the diaphragm have not been studied; thus we assessed diaphragm function in response to hypoxic breathing. Thirteen spontaneously breathing awake canines were exposed to moderate levels of sustained isocapnic hypoxia lasting 20–25 min (80 ± 2% pulse oximeter oxygen saturation). Breathing pattern and changes in muscle length and electromyogram (EMG) activity of the costal and crural diaphragm were continuously recorded. Mean tidal shortening and EMG activity of the costal and crural diaphragm exhibited an overall biphasic pattern, with initial brisk increase followed by a significant decline ( P < 0.01). Although costal and crural shortening did not differ significantly with sustained hypoxia, this equivalence in segmental shortening occurred despite distinct and differing EMG activities of the costal and crural segments. Specifically, initial hypoxia elicited a greater costal EMG activity compared with crural ( P < 0.05), whereas sustained hypoxia resulted in a lesser crural EMG decline/attenuation than costal ( P < 0.05). We conclude that sustained isocapnic hypoxia elicits a biphasic response in both ventilation and diaphragmatic function and there is clear differential activation and contribution of the two diaphragmatic segments. This different diaphragm segmental action is consistent with greater neural activation of costal diaphragm during initial hypoxia, then preferential sparing of crural activation as hypoxia is sustained. NEW & NOTEWORTHY In humans and other mammals, during isocapnic hypoxia sustained for 20–60 min ventilation exhibits a biphasic pattern: initial increase followed by significant ventilatory decline (“roll-off”). During sustained hypoxia, the function of the diaphragm is unknown. This study demonstrates that the diaphragm reveals a biphasic action during the time-dependent hypoxic “roll-off” in ventilation. These results also highlight that the two diaphragm segments, costal and crural, show differing, distinctive contributions to diaphragm function during sustained hypoxia.

Quality assurance (QA) in medicine is the practice of the prevention of errors and avoiding problems when delivering care in the form of medical therapy, both in terms of non-invasive and invasive procedures. It is rightly expected by patients. Up until the last 10 years, verification of intraoperative bypass graft patency was limited to a stable hemodynamic status, lack of electrocardiographic evidence of myocardial infarction and, if available, no new regional wall motion abnormalities on transesophageal echo. This perspective outlines two technologies for QA during coronary artery bypass graft (CABG) surgery: transit-time flow measurement (TTFM) for functional assessment of coronary grafts and anatomical evaluation with epicardial ultrasound (ECUS). TTFM is a seasoned technology, used since the late 1990s. ECUS is relatively new, used since 2012. TTFM alone, although useful for intraoperative bypass graft assessment, is not enough; 10-15% of graft values are ambiguous as to the efficacy of graft function. Therefore, although newer, ECUS is already being established as an indispensable tool for quality assessment in coronary surgery. The two modalities combined are vital for 'state of the art' intraoperative bypass graft assessment.

ObjectiveAt this consensus conference, we developed evidence-informed consensus statements and recommendations on the practice of off-pump coronary artery bypass graft (OPCAB) by systematically reviewing and performing meta-analysis of the randomized controlled trials (RCTs) comparing OPCAB and conventional coronary artery bypass (CCAB).MethodsAll RCTs of OPCAB versus CCAB through April 2013 were screened, and 102 relevant RCTs (19,101 patients) were included in a systematic review and meta-analysis (15 RCTs of 9551 high-risk patients; and 87 RCTs of 9550 low-risk patients) in accordance with the Cochrane Collaboration and PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) methodology. Consensus statements for the risks and benefits of OPCAB surgery in mortality, morbidity, and resource use were developed based on best available evidence.ResultsCompared to CCAB, it is reasonable to perform OPCAB to reduce risks of stroke [class IIa, level of evidence (LOE) A], renal dysfunction/failure (class IIa, LOE A), blood transfusion (class I, LOE A), respiratory failure (class I, LOE A), atrial fibrillation (class I, LOE A), wound infection (class I, LOE A), ventilation time, and ICU and hospital length of stay (class I, LOE A). However, OPCAB may be associated with a reduced number of grafts performed (class I, LOE A) and with diminished graft patency (class IIa, LOE A, with increased coronary reintervention at 1 year and beyond (class IIa, LOE A), as well as increased mortality at a median follow-up of 5 years (class IIb, LOE A).ConclusionsOPCAB compared with CCAB may improve outcomes in the short-term (stroke, renal dysfunction, blood transfusion, respiratory failure, atrial fibrillation, wound infection, ventilation time, and length of stay). However, over the longer-term, OPCAB may be associated with reduced graft patency, and increased risk of cardiac re-intervention and death.

Surgical treatment for angina pectoris was first proposed in 1899. Decades of experimental surgery for coronary artery disease finally led to the introduction of coronary artery bypass grafting (CABG) in 1964. Now that we are approaching 50 years of CABG experience, it is appropriate to summarize the advancement of CABG into a procedure that is safe and efficient. This review provides a historical recapitulation of experimental surgery, the evolution of the surgical techniques and the utilization of CABG. Furthermore, data on contemporary clinical outcomes are discussed.

Purpose A large multicenter randomized trial (RCT) is needed to assess off-pump coronary artery bypass graft (CABG) patency when performed by skilled surgeons. This prospective multicenter randomized pilot study compares graft patency after on-pump and off-pump techniques and addresses the feasibility of such an RCT. Materials and methods Consecutive patients were prospectively recruited for ≥64-slice computed tomography angiography graft patency assessment 1 year after randomization to off-pump or on-pump CABG. Blinded assessment of graft patency was performed, and the results were categorized as normal, ≥50% stenosis, or occlusion. A multilevel model with random effects on the patient was used to account for correlation of results in patients with multiple grafts. Results A total of 157 patients (3 centers, 84 off-pump and 73 on-pump patients, 512 grafts, assessability rate 98.4%) were included. Patency index (% nonoccluded grafts) was 89% for the off-pump technique and 95% for the on-pump technique (P=0.09). Patency was similar for arterial and vein grafts (both 92%; P=0.88), as well as between target territories (89% to 94%; P=0.53). Conclusions In this pilot study, 1-year graft patency results after off-pump and on-pump surgery were similar. This feasibility trial demonstrates that a large multicenter RCT to compare CABG patency after on-pump with that after off-pump techniques is feasible and can be reliably undertaken using computed tomography angiography.

ObjectiveCoronary artery bypass graft (CABG) surgery with arterial conduits is considered optimal. A deterrent to bilateral internal thoracic artery (BITA) grafting is the risk of deep sternal wound infection (DSWI). We introduced infection prevention measures sequentially, attempting to reduce DSWIs. The aim was to determine (1) if the absence of DSWIs in the last 469 of 1001 consecutive operations was significant; (2) which measures explained the change; and (3) the impact of diabetes.MethodsThe measures included internal thoracic artery (ITA) skeletonization, no bone wax, wound irrigation, 1 observer per case, harmonic scalpel harvest of ITAs, vancomycin paste on sternal marrow, iodine-impregnated skin drapes, chlorhexidine-alcohol skin preparation, no BITA grafts in obese, diabetic women, more off-pump procedures, aseptic wound care, and marrow irrigation before sternal approximation.ResultsMean age was 65 ± 10.4 years, 78% were male, 34% had diabetes, and 34% were obese. The first 532 patients had 16 DSWIs (3%) and the subsequent 469 had none (P

BackgroundIt appears that the medical profile of patients undergoing coronary artery bypass graft (CABG) surgery has changed. The impact of this demographic shift on CABG outcomes, such as sternal ...

Dissection of the left main coronary artery during coronary artery bypass graft (CABG) surgery is a rare, potentially lethal complication, usually diagnosed at post-mortem. During the cross-clamp period of a 4-vessel coronary artery bypass graft procedure in a 74-year old hypertensive woman, retrograde dissection occurred in a diffusely diseased marginal artery when perfused with cardioplegic solution at a pressure of 140-150 mmHg through a vein graft. The dissection extended back to the left main artery, included the posterior proximal ascending aorta and then down the left anterior descending artery (LAD). Transoesophageal echocardiography (TOE) confirmed the left main dissection and showed anterior-septal-lateral akinesis in a previously normally functioning left ventricle (LV). The circumferentially calcified proximal LAD was grafted with a saphenous vein by carving an oval area of calcium creating an elliptical opening in the artery wall. Normal LV function returned and, in the area of the left main dissection, there was only thickening with no colour flow. Eight months postoperatively cardiac catheterization showed normal LV function, patent vein grafts to the right coronary artery and proximal LAD, left internal mammary artery to distal LAD and an occluded sequential marginal vein graft. Twelve years postoperatively, the patient is well with Class I angina, on medication. There is no previous documentation of a diagnosed and successfully treated left main dissection during CABG surgery. Since this case using the technique of creating an oval opening in a circumferentially calcified coronary artery (with an otherwise satisfactory lumen), the author has been using this technique to bypass otherwise non-bypassable arteries; this technique may be useful to help patients with severe calcific coronary artery disease.

OBJECTIVES: Skeletonization of the internal mammary artery (IMA) facilitates arterial grafting and has been shown to reduce deep sternal infection but is more time-consuming and tedious than pedicle harvest. We wished to determine if use of harmonic technology (HT) facilitates skeletonization of the IMA and is as safe as the conventional technique of skeletonization. METHODS: In a consecutive series of 1057 patients with isolated coronary artery bypass graft (CABG) surgery from 2003 to 2013, adverse events and recorded harvest times were compared between harmonic (965 patients) and non-harmonic patients (86 patients). RESULTS: HT was used to harvest 1640 IMAs in 965 (91%) of 1057 consecutive CABG patients and skeletonization with the traditional technique (use of an electrocautery tip as a dissector) was used to harvest 147 IMAs in 86 patients. Six patients had no IMA harvested with this surgery (4 patients had an IMA used from a previous CABG, 1 had no disease of the left anterior descending coronary artery and 1 patient was in cardiogenic shock precluding IMA use). Excluding patients with single-vessel disease, 730/987 (74%) of patients received bilateral IMAs. Demographics of patients with and without harmonic skeletonization, respectively, were the following: mean age: 64.7 vs 67.7 years; diabetes: 33 vs 34%; women: 21 vs 26% and median European System for Cardiac Operative Risk Evaluation: 2.9 vs 3.2. The mean harvest time for 77 non-harmonic skeletonized mammary arteries (49 surgeries) was 32.2 min (95% confidence interval (CI): 30.1, 34.3), for harmonic skeletonized arteries after 450 surgeries was 28.4 min, (95% CI: 27.8, 29.1) and in the last 100 IMAs harvested for the isolated harmonic device use/mammary was 15.4 min (95% CI: 14.0, 16.7). Major adverse events for patients with and without harmonic skeletonization, respectively, were: reoperation for bleeding: 2.7 vs 3.5% (difference = 0.8%, 95% CI: −3.2, 4.8); damaged mammaries: 0.4 vs 0.7% (difference = 0.3%, 95% CI: −1.0, 1.7); deep sternal infection: 1.6 vs 1.2% (difference = −0.4%, 95% CI: −2.8, 2.0) and perioperative infarction: 1.7 vs 2.3% (difference = 0.7%, 95% CI: −2.6, 4.0). CONCLUSION: In this largest series to date of harmonic IMA skeletonization, this technique results in rare damage, is quicker and with a comparable adverse event rate compared with the non-harmonic method.

Background The efficacy of coronary artery bypass graft surgery (CABG) and percutaneous coronary intervention (PCI) in patients with coronary artery disease has been well defined by randomized controlled trials. However, patients with severe left ventricular dysfunction (ejection fraction Methods The Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease (APPROACH), a clinical data collection and outcome monitoring initiative for the province of Alberta, Canada, was used to identify 2925 patients with coronary artery disease and left ventricular dysfunction undergoing CABG (n = 1,326) or PCI (n = 1,599) between 1995 and 2008. Patients were propensity matched to obtain comparable subgroups among left ventricular dysfunction patients. Results Cox proportional hazard analysis of the propensity-matched subgroups identified that CABG was significantly associated with lower rates of repeat revascularization and better survival compared with PCI at 1, 5, 10, and 15 years. Other significant independent predictors of poor long-term survival included age, renal failure, heart failure, diabetes mellitus, peripheral vascular disease, prior myocardial infarction, left main coronary artery disease, and prior CABG. Conclusions For patients with coronary artery disease and left ventricular dysfunction, CABG was associated with lower rates of repeat revascularization and improved survival over PCI, after adjustment for baseline risk profile differences. Further research exploring the factors leading to use of a particular revascularization modality in this patient population is required.

textabstractPurpose of Review: Arterial grafting is superior to venous grafting in coronary artery bypass graft surgery with respect to graft patency and long-term patient outcome, but it may be difficult to achieve complete arterial revascularization. Recent Findings: Use of arterial grafts, especially bilateral internal mammary artery grafts, is not common, whereas there are clear indications that it may increase survival. Definitions of complete revascularization are varied and confusing, making study comparisons difficult. Technical challenges in complete revascularization with arterial grafts can be minimized by surgical techniques. Competitive flow in moderately stenosed coronary arteries grafted with arterial conduits may result in reduced patency. While internal mammary arteries may be used in arteries with at least 60% stenosis, radial artery and gastroepiploic grafts are best placed onto coronaries with severe stenosis. Moderate lesions in the left coronary circulation should be bypassed, but right coronary artery lesions can be left untouched as there is minimal progression over time. Complete revascularization may not be necessary or possible in every patient because of technical challenges. CONCLUSION: Complete revascularization with arterial grafts presents both technical and physiological challenges. However, with techniques to maximize length of arterial conduits, knowledge of competitive flow and which moderate lesions should be addressed, complete revascularization with arterial grafts can be accomplished in the majority of patients, notwithstanding it may not be possible or even indicated for every patient.

OBJECTIVES: The purpose of this study was to compare effectiveness of the 1999 logistic EuroSCORE (LES) and of the 2012 EuroSCORE II (ESII) in a real-world patient population of 1125 patients undergoing total arterial grafting (TAG) coronary artery bypass graft (CABG) surgery. METHODS: The performance of the two risk scores was compared using (i) discrimination (accuracy of discriminating non-survivors from survivors), (ii) calibration (assessment of agreement between the predicted/observed outcomes) and (iii) agreement between the two scores. By averaging medians of LES and ESII and then sub-division into 10 equal groups, actual operative mortality rate was compared with the median LES and ESII within each risk group, the difference plotted against the average risk score (as in a Bland and Altman plot), and using the traditional risk groupings for EuroSCORE of low (0-2.99), medium (3-5.99) and high risk (6.0 and above), the reclassification rate of ESII was compared with that of LES. RESULTS: In 1125 consecutive total arterial CABG patients, demographics included: mean age 64.6 years, 79% males, 35% diabetic patients, 57% urgent/emergent patients, 37% off-pump and 77% bilateral mammary grafting. Overall operative mortality was 3.2% (36 patients). Comparison of the LES and ESII showed (i) good discrimination for both LES and ESII (area under the curve for LES was 0.85 and for ESII was 0.87); (ii) neither score was well calibrated: LES tended to overestimate and ESII underestimated risk. In general, the ESII provided a better estimate of risk in lower risk patients and LES was better for the highest risk group. (iii) In terms of agreement, in the lower four risk groups the risk was overestimated by both scores, in five of the higher six risk groups ESII underestimated risk and LES overestimated risk, and in the highest risk group LES was very close (17.2 cf. 17.7) compared with ESII (5.6 cf. 17.7). In addition, ESII downgraded risk in 96.8% of survivors and in 97.2% of non-survivors. CONCLUSIONS: In 1125 consecutive TAG CABG patients, neither LES nor ESII performed well enough to be used as a consistent risk stratification tool; LES overestimated risk but was highly accurate for the highest of 10 risk groups and ESII consistently underestimated risk in all patients.

Background: Remote ischemic preconditioning is a simple therapy that may reduce cardiac and kidney injury. We undertook a randomized controlled trial to evaluate the effect of this therapy on markers of heart and kidney injury after cardiac surgery. Methods: Patients at high risk of death within 30 days after cardiac surgery were randomly assigned to undergo remote ischemic preconditioning or a sham procedure after induction of anesthesia. The preconditioning therapy was three 5-minute cycles of thigh ischemia, with 5 minutes of reperfusion between cycles. The sham procedure was identical except that ischemia was not induced. The primary outcome was peak creatine kinase–myocardial band (CK-MB) within 24 hours after surgery (expressed as multiples of the upper limit of normal, with log transformation). The secondary outcome was change in creatinine level within 4 days after surgery (expressed as log-transformed micromoles per litre). Patient-important outcomes were assessed up to 6 months after randomization. Results: We randomly assigned 128 patients to remote ischemic preconditioning and 130 to the sham therapy. There were no significant differences in postoperative CK-MB (absolute mean difference 0.15, 95% confidence interval [CI] −0.07 to 0.36) or creatinine (absolute mean difference 0.06, 95% CI −0.10 to 0.23). Other outcomes did not differ significantly for remote ischemic preconditioning relative to the sham therapy: for myocardial infarction, relative risk (RR) 1.35 (95% CI 0.85 to 2.17); for acute kidney injury, RR 1.10 (95% CI 0.68 to 1.78); for stroke, RR 1.02 (95% CI 0.34 to 3.07); and for death, RR 1.47 (95% CI 0.65 to 3.31). Interpretation: Remote ischemic precnditioning did not reduce myocardial or kidney injury during cardiac surgery. This type of therapy is unlikely to substantially improve patient-important outcomes in cardiac surgery. Trial registration: ClinicalTrials.gov, no. NCT01071265.

Objective: Endothelial dysfunction, specifically endothelium-derived contracting factors have been implicated in the development of arterial conduit vasospasm. The potent vasoconstrictor endothelin-1 (ET-1) has received much attention in this regard. The present study was designed to evaluate the role of ET-1 in the development of endothelial dysfunction in human internal mammary arteries (IMA). To this aim, we examined the effects of specific and non-specific ET-receptor antagonists on endothelial function (assessed using acetylcholine (ACh)-induced vasodilation) in segments of IMA obtained during coronary artery bypass graft (CABG) surgery. Methods: Vascular segments of IMA were obtained from 51 patients undergoing elective coronary artery bypass graft (CABG) surgery and in vitro endothelium-dependent and -independent responses to ACh and sodium nitroprusside (SNP) were assessed. Isometric dose response curves (DRC) to ACh and SNP were constructed in pre-contracted rings in the presence and absence of bosentan (ETA/B receptor antagonist, 3 μM), BQ-123 (ETA antagonist, 1 μM) and BQ-788 (ETB antagonist, 1 μM) using the isolated organ bath apparatus. Percent maximum relaxation (% E max) and sensitivity (pEC50) were compared between interventions. Results: ACh caused dose-dependent endothelium-mediated relaxation in IMA (% E max 43±4, pEC50 6.74±0.12). In the presence of bosentan, BQ-123 and BQ-788 ACh-induced relaxation was significantly augmented (% E max bosentan 60±3, BQ-123 56±4, BQ-788 53±5 vs. control 43±4, P 0.05). Conclusions: These data uncover, for the first time, beneficial effects of ET receptor blockade on endothelial-dependent vasorelaxation in human IMA.

Pulmonary complications after upper abdominal surgery are usually ascribed to temporary postoperative impairment of diaphragm function, which may not originate from intrinsic, structural injury but from reflex inhibition of diaphragm contractility. Spontaneous breathing is interrupted periodically by sighs, even after upper abdominal surgery. If postoperative dysfunction of the diaphragm arises from a reflexic inhibition, then the sigh should temporarily override the inhibition and restore normal diaphragm function. We implanted sonomicrometer and electromyogram transducers chronically in six dogs by laparotomy, then directly measured length, shortening, and electromyogram activity of costal and crural diaphragm segments, parasternal intercostal, and transversus abdominis muscles an average of 8.7 (range, 1-16) d later during resting tidal breathing and sighs. In each animal we analyzed a sequence of breaths, including a sigh, when costal or crural diaphragm contractility was abnormal. With each sigh, the shape and amplitude of costal and crural diaphragm segmental shortening improved abruptly, from 0.9 and 1.4% of baseline length (% LBL) during resting breathing to 12.1 and 11.1% LBL, respectively, during sighs. The sighs were compared to CO2-stimulated breaths of equivalent tidal volume, which did not show either pattern or amplitude of shortening equivalent to sighs. We conclude that diaphragm dysfunction after laparotomy arises from a reflex inhibition, which is overridden abruptly to return diaphragm function briefly to normal during each spontaneous sigh.

Since first introduced in the mid-1960s, coronary artery bypass grafting (CABG) has become the standard of care for patients with coronary artery disease. Surprisingly, the fundamental surgical technique itself did not change much over time. Nevertheless, outcomes after CABG have dramatically improved over the first 50 years. Randomized trials comparing percutaneous coronary intervention (PCI) to CABG have shown converging outcomes for select patient populations, providing more evidence for wider use of PCI. It is increasingly important to focus on the optimization of the short- and long-term outcomes of CABG and to reduce the level of invasiveness of this procedure. This review provides an overview on how new techniques and widespread consideration of evolving strategies have the potential to optimize outcomes after CABG. Such developments include off-pump CABG, clampless/anaortic CABG, minimally invasive CABG with or without extending to hybrid procedures, arterial revascularization, endoscopic vein harvesting, intraprocedural epiaortic scanning, graft flow assessment, and improved secondary prevention measures. In addition, this review represents a framework for future studies by summarizing the areas that need more rigorous clinical (randomized) evaluation.

OBJECTIVES: The management strategy remains controversial for patients presenting with type A acute aortic dissection with cerebrovascular accident or coma. The present study aimed to help guide surgeons treating these high-risk patients. METHODS: Of 1873 patients with type A acute aortic dissection enrolled in the International Registry for Acute Dissection, 87 (4.7%) presented with cerebrovascular accident and 54 (2.9%) with coma. The hospital and 5-year results were stratified by the presence and type of brain injury (no injury vs stroke vs coma) and management type (medical vs surgical). Independent predictors of short- and mid-term survival were identified. RESULTS: Presentation with shock, hypotension, or tamponade (46.8% vs 25.2%; P < .001) and arch vessel involvement (55.0% vs 36.1%; P < .001) was more likely in patients with brain injury. Surgical management was avoided more often in patients with coma (33.3%) or cerebrovascular accident (24.1%) than in those without brain injury (11.1%; P < .001). The overall hospital mortality was 22.7% without brain injury, 40.2% with cerebrovascular accident, and 63.0% with coma (P < .001). Mortality varied among the management types for both cerebrovascular accident (76.2% medical vs 27.0% surgical; P < .001) and coma (100% medical vs 44.4% surgical; P < .001). Postoperatively, cerebrovascular accident and coma resolved in 84.3% and 78.8% of cases, respectively. On logistic regression analysis, surgery was protective against mortality in patients presenting with brain injury (odds ratio 0.058; P < .001). The 5-year survival of patients presenting with cerebrovascular accident and coma was 23.8% and 0% after medical management versus 67.1% and 57.1% after surgery (log rank, P < .001), respectively. CONCLUSIONS: Brain injury at presentation adversely affects hospital survival of patients with type A acute aortic dissection. In the present observational study, the patients selected to undergo surgery demonstrated improved late survival and frequent reversal of neurologic deficits.

We thank Collins and Le Manach for their insightful comments on our paper and also for drawing our attention to their article on sample sizes for external validation of prognostic models, which unfortunately was unavailable when our data were analysed. However, their article examined the effect of sample size for proportional hazards models and we used a logistic regression model (with previously published papers more applicable to the assessment of appropriate sample size).

BACKGROUND To determine the transmural pressure-dimension relations of the right atrium (RA) and right ventricle (RV) before and after pericardiectomy, six open-chest dogs were instrumented with pericardial balloons placed over the RA and RV free walls. METHODS AND RESULTS PA appendage dimensions and RV free-wall segment lengths were measured using sonomicrometry. Intact-pericardium RA and RV transmural pressures were calculated by subtracting the pericardial pressures (measured using balloons) from the cavitary pressures. Pooled data from six animals with pericardium intact indicate that at RA and RV cavitary pressures of 5, 10, and 15 mm Hg, RV pericardial pressure was 4.3 +/- 0.3, 8.6 +/- 1.0, and 13.3 +/- 1.5 mm Hg, respectively, and RA pericardial pressure was 4.8 +/- 0.3, 9.6 +/- 0.6, and 14.6 +/- 0.6 mm Hg, respectively (mean +/- SD). With calculated unstressed dimensions, the cavity dimension data were normalized to strain (in percent). We determined that in the dog, RV strain would increase by 14% and RA by 68% to maintain cavitary pressure at 10 mm Hg on pericardiectomy. To compare these results with clinical data, RV (n = 7) and RA (n = 6) transmural pressures were measured using balloons in patients (age, 19 to 76 years) undergoing cardiac surgery. RA transmural pressure of six patients was 1.0 +/- 1.5 mm Hg when central venous pressures (CVPs) ranged from 3 to 16 mm Hg. RV transmural pressure equaled 1.2 +/- 1.9, 2.3 +/- 1.9, and 3.4 +/- 2.0 mm Hg when CVP was 5, 10, and 15 mm Hg, respectively. CONCLUSIONS Pericardial constraint (as evaluated by the ratio of pericardial to intracavitary pressures when CVP is 10 mm Hg) accounted for 96% of RA cavitary pressure in the dog and 89% in humans and at least 86% of RV cavitary pressure in the dog and 77% in humans.

In humans and some animals, the surviving respiratory muscles are able to compensate fully for unilateral, and partially for bilateral, hemidiaphragm paralysis. To examine differential activity of individual respiratory muscles after unilateral or bilateral diaphragm paralysis, length and electromyogram (EMG) of left costal and crural diaphragm segments, parasternal intercostal, and transversus abdominis were measured directly in five awake canines after implantation with sonomicrometry transducers and bipolar EMG electrodes under three conditions: during normal breathing (NOFRZ), after infusion of local anesthetic (bupivacaine) through a cervical phrenic nerve cuff to induce reversible contralateral hemidiaphragm (CNFRZ), and after bilateral diaphragm (BIFRZ) paralysis. From NOFRZ to CNFRZ, costal, crural, parasternal, and transversus abdominis increased shortening and EMG activity to compensate for contralateral diaphragm paralysis, but the increase in activity was not equivalent for each muscle. With BIFRZ, parasternal and transversus abdominis showed further increases in activity, coordinated between both inspiration and expiration. Normalized intrabreath profiles revealed dynamic differences in development of muscle activity within each breath as paralysis worsened. Review of simultaneous muscle activities showed coordinated interactions among the compensating muscles: passive shortening of transversus, and lengthening of costal and crural, coincided with increased active inspiratory shortening of parasternal. We conclude that an integrated strategy of respiratory muscle compensation for unilateral or bilateral diaphragm paralysis occurs among chest wall, abdominal, and diaphragm segmental muscles, with relative contributions of individual muscles adjusted according to the degree of diaphragm dysfunction.

Background We previously established a proof-of-concept in a human cadaveric model where conventional wire cerclage was augmented with a novel biocompatible bone adhesive that increased mechanical strength and early bone stability. We report the results of a single-center, pilot, randomized clinical trial of the effects of adhesive-enhanced closure of the sternum on functional postoperative recovery. Methods In 55 patients undergoing primary sternotomy, 26 patients underwent conventional wire closure and were compared with 29 patients who underwent adhesive-enhanced closure, which consisted of Kryptonite biocompatible adhesive (Doctors Research Group Inc, Southbury, CT) applied to each sternal edge in addition to conventional 7-wire cerclage. Patients were monitored postoperatively at 72 hours, weekly for 12 weeks, and then after 12 months for incisional pain, analgesic use, and maximal inspiratory capacity measured by spirometry. Standardized assessment tools measured postoperative physical disability and health-related quality of life. Results No adverse events or sternal complications from the adhesive were observed early or after 12 months. Incisional pain and narcotic analgesic use were reduced in adhesive-enhanced closure patients. Inspiratory capacity was significantly improved, postoperative health-related quality of life scores normalized more rapidly, and physical disability scores were reduced. Computed tomography imaging was suggestive of sternal healing. Conclusions Adhesive-enhanced closure is a safe and simple addition to conventional wire closure, with demonstrated benefits on functional recovery, respiratory capacity, incisional pain, and analgesic requirements. A large, multicenter, randomized controlled trial to examine the potential of the adhesive to prevent major sternal complications in higher risk patients is warranted.