Coronary Graft Failure Research Articles

Intraoperative Prediction of Coronary Graft Failure Based on Transit Time Flow Measurement: A PRELIMINARY STUDY.

Myocardial revascularization has been known to not affect the prognosis in some patients. Coronary artery bypass graft (CABG) failure may develop one year after CABG surgery. This is accompanied by a high risk of developing myocardial infarction after complete myocardial revascularization in obstructive coronary artery disease (CAD) due to microvascular dysfunction. The study of microvascular dysfunction using intraoperative stress tests with adenosine triphosphate (ATP) allows for the assessment of the coronary bypass flow reserve (CBFR) and the risk of graft failure one year after surgery. The study included 79 CAD patients (238 grafts) who underwent dynamic single-photon emission computed tomography (SPECT) before CABG and dynamic transit time flow measurement (TTFM) during CABG at rest and at stress. The CBFR was calculated by the ratio of the mean graft flow (MGF) at stress to the MGF at rest. A multivariate regression model showed that the MGF at rest (p = 0.043), the MGF at stress (p = 0.026) and the CBFR (p = 0.0001) were significant independent predictors of graft failure. As a result of ROC analysis, the threshold CBFR < 1.67 units correlated with graft failure more closely (sensitivity 82%, specificity 90%) The CBFR is a significant independent predictor of graft failure for up to 16 months.

Angiographic definition, incidence, predictors and clinical impact of early coronary graft failure in patients undergoing coronary artery bypass graft surgery

Abstract Introduction Coronary graft failure (CGF) may occur early after coronary bypass graft surgery (CABG), potentially leading to adverse clinical outcomes. However, data regarding incidence, diagnostic strategies and identification of individuals at risk of developing early CGF are scarce. Purpose The aim of this study was to establish a definition of early CGF based on invasive coronary angiography (CAG), to identify clinical and perioperative risk factors of early CGF and to define the clinical impact of early CGF in terms of major adverse cardiovascular events (MACE: death, myocardial infarction and revascularisation) at 5-years follow-up. Methods This retrospective observational study included CABG patients who underwent CAG prior to post-surgery discharge between 2012-2022 in a tertiary center. The decision to perform a CAG was based on clincal criteria indicative of myocardial ischemia. All CAGs were reviewed by two interventional cardiologist and a thoracic surgeon. Early CGF was defined as a dysfunctional coronary graft resulting from any of the following angiographic findings: stenosis of proximal or distal anastomosis, stenosis of the bypass conduit, bypass occlusion, reduced bypass flow (TIMI&amp;lt;1) and kinking/tenting/dissection of the bypass leading to lumen reduction. Clinical data and ECG recordings during hospitalization were collected. Comparisons between patients with vs. without early CGF were performed. Kaplan-Meier analysis was performed to estimate cumulative survival free of MACE at 5-years follow-up. Multivariate analysis was performed to identify predictors of early CGF. Results A total of 92 patients (79% male, 66.1±10 years-old) were included. CGF was present in 55 patients (60%). Compared to the patients without graft failure (n=37 (40%), there were no differences in baseline demographics and intra- and postoperative technical and clinical parameters. At 5-years follow-up, MACE was observed in 57 patients (18 death, 34 myocardial infarction, 42 revascularization). There were 50 revascularization procedures performed in 42 patients (46%). Of them, 35 (83%) were performed in patients with early CGF vs. 7 (17%) in patients without CGF (p&amp;lt;0.001). Patients with early CGF showed a significantly lower MACE-free five-year survival rate (p&amp;lt;0.001) (Figure) 1). On multivariate analysis, venous grafts (p=0.006), Y-graft configuration (p&amp;lt;0.001) and the need of inotropic agents for hemodynamic support (p=0.029) showed a significant association with early CGF. Conclusion In CABG patients undergoing clinically indicated CAG prior to discharge, early CGF was observed in 60%. Most patients underwent new revascularisation. Patients with early CGF showed a higher rate of MACE at 5-years follow-up, emphasizing the necessity to recognize and treat CGF. Venous grafts, Y-graft configuration and the need of inotropic agents for hemodynamic support 12h postoperatively were associated with early CGF.

The Year in Cardiothoracic and Vascular Anesthesia: Selected Highlights From 2023

This special article is the 16th in an annual series for the Journal of Cardiothoracic and Vascular Anesthesia. The authors thank the editor-in-chief, Dr. Kaplan, and the editorial board for the opportunity to continue this series, namely the research highlights of the past year in the specialty of cardiothoracic and vascular anesthesiology. The major themes selected for 2023 are outlined in this introduction, and each highlight is reviewed in detail in the main article. The literature highlights in the specialty for 2023 begin with an update on perioperative rehabilitation in cardiothoracic surgery, with a focus on novel methods to best assess patients in the preoperative and postoperative periods, and the impact of rehabilitation on outcomes. The second major theme is focused on cardiac surgery, with the authors discussing new insights into inhaled pulmonary vasodilators, coronary revascularization surgery, and discussion of causes of coronary graft failure after surgery. The third theme is focused on cardiothoracic transplantation, with discussions focusing on bridge-to-transplantationstrategies. The fourth theme is focused on mechanical circulatory support, with discussions focusing on bothtemporary and durable support. The fifth and final theme is an update on medical cardiology, with a focus on outcomes ofinvasive approaches to heart disease. The themes selected for this article are only a few of the diverse advances in the specialty during 2023. These highlights will inform the reader of key updates on various topics, leading to improved perioperative outcomes for patients with cardiothoracic and vascular disease.

Impact of acute coronary graft failure and subsequent urgent endovascular revascularization after planned coronary artery bypass grafting on hospital outcome

Highlights The authors conducted a comparative analysis of early postoperative complications, mortality and economic costs in patients who underwent additional urgent endovascular revascularization and patients with standard postoperative period.There are statistically significant differences between the groups in terms of the number of resternotomies performed, the need for transfusable blood components and economic costs.It is necessary to introduce routine intraoperative quality control of the intervention, and a set of measures aimed at early detection of coronary graft failure in real clinical practice. Abstract Aim. To assess the impact of coronary graft failure and subsequent urgent endovascular revascularization in the early postoperative period after elective coronary artery bypass grafting on hospital outcome.Materials and methods. 8801 patients underwent isolated coronary artery bypass grafting at the Federal State Budgetary Institution “Federal Center for Cardiovascular Surgery” of the Ministry of Health of the Russian Federation in Chelyabinsk from 2011 to 2020. Inclusion criteria were as follows: patients with stable coronary heart disease, patients undergoing elective coronary artery bypass grafting. Exclusion criteria were as follows: patients with unstable angina and acute myocardial infarction who underwent urgent revascularization. The primary endpoint was hospital mortality, secondary endpoints are bleeding requiring resternotomy, acute abdominal and infectious complications, and multiple organ failure. Due to suspected acute myocardial injury, 196 (2.23%) patients underwent urgent coronary angiography, and according to angiogram, additional endovascular correction was performed in 60 (0.68%) patients (the group I). To assess the impact of coronary graft failure and subsequent revascularization on hospital outcome we have analyzed: hospital mortality, complications in the early postoperative period, financial costs. Moreover, we have formed the group II of 60 people with uncomplicated postoperative period for comparative analysis.Results. Of 196 (2.23%) patients who underwent urgent angiography 60 (0.68%) patients required stenting of native coronary arteries or conduits due to coronary graft failure. Hospital mortality in the group with complicated postoperative period was 10 % (6 cases), hemorrhagic complications occurred in 13 (21.7%) patients, acute abdomen was noted in 4 patients, and sternal wound infection was noted in 5 patients, hemodialysis due to multiple organ failure was performed in 5 patients. An intergroup comparative analysis revealed a clear trend towards an increase in deaths in the group I (n = 6/10%) compared to the group II (n = 1/1.7%), however, there were no significant differences (p = 0.11F). Hemorrhagic complications occurred significantly higher in group I (13/21.7% versus 1/1.7%, p = 0.001F); there were no statistically significant differences associated with the other complications. The number of bed-days spent in the hospital and in the intensive care unit was statistically significantly higher in the group I, financial costs per patient were also significantly higher in the group I.Conclusion. Coronary bypass graft failure in the early postoperative period leads to an increase in hospital mortality, in the frequency of multiple organ failure and hemorrhagic complications, and significantly increases the amount of needed economic resources.

Strengthening the quality control of coronary artery bypass grafting

The quality control of coronary artery bypass grafting (CABG) is an important prerequisite to the graft patency and the long-term outcomes. The evaluation of target vessel is the basis, the choice of surgical types is the means, the high-quality acquisition of graft harvesting is the guarantee, and the anastomotic method and quality is the core. As the most commonly used quality control tool, intraoperative transit time flow measurement can effectively detect the coronary graft failure caused by anastomotic stenosis and guide to repair of the graft. However, some studies showed that the positive predictive value is low, and the evidence is insufficient for the relationship with the long-term patency rate of grafts. Intraoperative instantaneous flow measurement combined with high-resolution epicardial ultrasound can improve the quality, safety and effectiveness of CABG, which should be an important recommendation for CABG quality control. Once the shape of the grafts and anastomotic ports is abnormal and the blood flow is not satisfied, it needs to adjust or re-anastomose immediately. The quality control of CABG requires comprehensive judgment and individualized measures to ensure the safety and long-term outcome of patients.

Internal mammary artery graft failure: Clinical features, management, and long-term outcomes

ObjectiveData on long-term outcomes after internal mammary artery (IMA) coronary graft failure are scarce. Our objective was to describe the clinical characteristics, management, and prognosis after angiographically confirmed IMA graft failure following coronary revascularization. MethodsA three-hospital retrospective registry, observational and descriptive, with prospective follow-up of all consecutive cases of IMA graft failure between 2004 and 2014 was conducted. After treatment, clinical and procedural features were compared between those with and without cardiovascular events. ResultsFifty-seven patients were included (89% male, mean age: 62 years, at surgery) in the registry. Most patients underwent an IMA angioplasty (percutaneous coronary intervention [PCI], 74%). In nine cases, the PCI failed at the graft level, and seven underwent a native vessel revascularization. Native vessel treatment was performed in 20% of the study subjects, all with stents. Finally, medical management was decided in three cases. Events after treatment for IMA graft failure were frequent (50.8%), during a median follow-up of 7.5 years. Acute presentation (hazard ratioMACE = 1.35; 95% confidence interval (CI): 1.12–3.00, p < 0.01), age of the patient (hazard ratioMACE = 1.85, 95% CI: 1.17–2.11, p < 0.01), presence of diabetes mellitus (hazard ratioMACE = 2.75, 95% CI: 1.13–6.69, p = 0.02), and the management modality used (IMA-simple angioplasty VS IMA-stenting: hazard ratioMACE = 5.5, 95% CI: 1.40–21.15, p = 0.01) displayed prognostic relevance on multivariate analysis. All-cause mortality occurred in 21.1% and presentation as infarction (hazard ratioDEATH = 1.05, 95% CI: 1.01–2.17, p = 0.01), age (hazard ratioDEATH = 9.08, 95% CI: 2.52–32.69, p < 0.01), and left ventricular ejection fraction (hazard ratioDEATH = 3.68, 95% CI: 1.65–8.18, p < 0.01) were independent predictors of the same. ConclusionsIn this long-term registry, most patients presented with an acute condition (myocardial infarction, progressive angina) within 12 months after surgery. Acute presentation, age, diabetes mellitus, reduced left ventricular ejection fraction, IMA graft failure segment affected, and the management strategy were related with long-term prognosis.

Mechanisms, Consequences, and Prevention of Coronary Graft Failure.

Graft failure occurs in a sizeable proportion of coronary artery bypass conduits. We herein review relevant current evidence to give an overview of the incidence, pathophysiology, and clinical consequences of this multifactorial phenomenon. Thrombosis, endothelial dysfunction, vasospasm, and oxidative stress are different mechanisms associated with graft failure. Intrinsic morphological and functional features of the bypass conduits play a role in determining failure. Similarly, characteristics of the target coronary vessel, such as the severity of stenosis, the diameter, the extent of atherosclerotic burden, and previous endovascular interventions, are important determinants of graft outcome and must be taken into consideration at the time of surgery. Technical factors, such as the method used to harvest the conduits, the vasodilatory protocol, the storage solution, and the anastomotic technique, also play a major role in determining graft success. Furthermore, systemic atherosclerotic risk factors, such as age, sex, diabetes mellitus, hypertension, and dyslipidemia, have been variably associated with graft failure. The failure of a coronary graft is not always correlated with adverse clinical events, which vary according to the type, location, and reason for failed graft. Intraoperative flow verification and secondary prevention using antiplatelet and lipid-lowering agents can help reducing the incidence of graft failure.

Early platelet recovery following cardiac surgery with cardiopulmonary bypass

Coronary artery bypass grafting (CABG) with cardiopulmonary bypass (CPB) is frequently associated with low platelet count (PC) and disturbed platelet function (PF). While PC is easy to measure, PF is more difficult to assess. Moreover, the time-related platelet dysfunction and recovery after CPB is not fully elucidated. Platelet dysfunction could lead to bleeding but also to coronary graft failure. Laboratory tests could provide more insights into PF after CABG. The aim of the current study was to investigate the time-related PF induced by CPB. Blood samples of 20 patients with a preoperative PC of more than 250 × 109/L were collected before incision, after weaning from CPB, and 24 h postoperative. Platelet contribution to coagulation was quantified by PLTEM (calculated by means of EXTEM and FIBTEM results). PF was assessed by multiple electrode impedance aggregometry (MEIA) in whole blood and by light transmission aggregometry (LTA) in platelet-rich plasma after stimulation with arachidonic acid (AA), adenosine diphosphate, collagen, and thrombin-receptor-activating peptide. LTA and MEIA analysis demonstrated significant platelet dysfunction after CPB, with partial recovery within 24 h after surgery. AA-induced platelet aggregation increased to higher levels within 24 h after surgery compared to baseline values as measured by LTA. PLTEM maximum clot firmness remained unchanged throughout the study. Correlation analyses revealed that MEIA and rotational thromboelastometry (ROTEM), but not LTA, were dependent on PC and hematocrit. No correlations were found between LTA, MEIA, ROTEM, PC, and clinical outcome parameters. Our results demonstrate a reversible platelet dysfunction recovering within 24 h after CPB. Interestingly, AA-induced platelet aggregation increases to higher levels during the first 24 h postoperatively, which might be important for early initiation of antiplatelet therapy after CABG. MEIA as POC test is able to detect platelet dysfunction during cardiac surgery with a PC of ≥150 × 109/L.

Weaning from cardiopulmonary bypass

The main goal of weaning from cardiopulmonary bypass (CPB) is a smooth transition from mechanical pump-assisted circulation to spontaneous heart activities with sufficient blood flow to maintain systemic circulation. Before initiation of weaning from the CPB, optimal condition for re-beating should be prepared. Normothermia (core temperature > 36℃) is achieved by actively re-warming through the CPB heat exchanger, active warming devices. However, core temperature should not be exceeded by more than 38℃ to avoid postoperative neurological dysfunction [1]. The findings of laboratory data should be within normal ranges. Arterial blood gas analysis is carried out to identify oxygen content of the blood as hematocrit (> 25%), hemoglobin (> 7 g/dl), PaO2 (> 100 mmHg) and absence of metabolic, electrolytic disturbances. The anesthesiologists restart sleeping alarms and adjust monitors, ventilator settings and oxygen flows. After aortic declamping, heart re-beat spontaneously in most cases with minor supportive interventions such as electrical defibrillation, pace maker, and small dose of inotropics. Atrial kick contributes more than 20% of ventricular filling, returning and maintaining of normal sinus rhythm (heart rate between 70-100 beats per min) is preferable. Electric conversion of supraventricular tachycardia, atrial fibrillation and temporary cardiac pacing for atrioventricular conduction block should be considered. Optimized preload is achieved by volume control, mean arterial pressure maintained within 70-90 mmHg with vasoactive agents. In case of inability to wean from CPB despite preload optimization, global cardiac function and completeness of surgery should be assessed by transesophageal echocardiography (TEE) examination. Most common causes of weaning difficulty are left and/or right ventricular failures and inappropriate vasodilatation. TEE allows diagnostic and therapeutic decision makings, and appropriate treatment option. Routine TEE examinations before terminating the CPB is essential for detecting unexpected problems such as an iatrogenic aortic dissection from arterial cannulation site or intracardiac thrombus formations even after full heparinization or any other anatomical anomalies [2,3]. Because of major complication of TEE probe insertion is the esophageal injury, anesthesiologists carefully manipulate TEE probe, especially patient with an esophageal pathology preoperatively [4]. Faultiness of surgery should be excluded (valvular dysfunction, coronary graft failure, left ventricular outflow obstruction) by TEE examinations, and vasoplegic syndrome managed by vasopressor administration [5]. The recently emerged minimally-invasive hemodynamic monitoring devices can assess the cardiac output, preload, intrathoracic volume and tissue oxygenation which might be guide weaning management with real time inspections of responsiveness of fluid loading and vasoactive agents [6]. Patients with risk factor of ventricular dysfunction (elderly, chronic beta-blocker treatment, renal failure, pulmonary hypertension) tend to be difficult in weaning from CPB, awareness of these risk factors are important for preparing and planning aggressive cardiosupportive management earlier as prophylactic intervention [7]. Protamine sulfate is administrated slowly in order to neutralize generalized heparinization. Thromboelastography as a point-of-care monitoring device can provide rapid information about global hemostatic states (from clot formation, stabilization to fibrinolysis) to achieve goal oriented transfusions during the cardiac operation [8]. Weaning from CPB is associated with complicated problems and requires multiplinary approaches simultaneously. According to observational studies, there were strong correlations between the technical errors and teamwork disruptions caused by poor communication and lack of information during weaning period in cardiac teams [9]. The weaning moment is a critical time for confirming and verifying surgical results and achieving the optimization of hemodynamics. Thus, important information and process should be shared and fully communicated among the anesthesiologist, the cardiac surgeon, and the perfusionist.

Predicting the future of human gene therapy for cardiovascular diseases: what will the management of coronary artery disease be like in 2005 and 2010?

Gene therapy is the use of gene delivery as a means to achieve high levels of the therapeutic gene product (ie, “drug” delivery) to treat acquired cardiovascular diseases. Human gene therapy for cardiovascular disease is expected to provide important advances in therapeutic angiogenesis, myocardial protection, myocardial regeneration and repair, restenosis, prevention of bypass graft failure, and risk-factor management. The data from ongoing phase 2 and future phase 3 studies will provide evidence to show whether therapeutic angiogenesis is effective, and these studies will identify the types of patients who may benefit. An important therapeutic target is the cell cycle. Data from the Project in Ex-Vivo Vein Graft Engineering via Transfection (PREVENT) I and II studies suggest that a synthetic DNA decoy can sequester the E2F family of transcription factors and arrest cells at the gap period (G1) checkpoint. This mechanism prevents intimal hyperplasia, which is associated with atherosclerosis and coronary graft failure. Administration of a myocardial protective gene (eg, heme oxygenase) via a recombinant adeno-associated virus vector reduces infarct size in animal models of ischemia and reperfusion. Other studies have shown that fractionated bone marrow stem cells promote myocardial repair and regeneration in myocardial infarction. If applied in humans, it will be possible to use a single administration of gene therapy to provide long-term prophylaxis against secondary coronary events and to promote myocardial repair in patients who have experienced an infarct, as well as in those at high risk of myocardial injury. In the future, new technology using stable gene integration may lead to the development of more effective and lifelong therapy for diabetes, familial homozygous hypercholesterolemia, and other acquired diseases.

Ultrasonic assessment of internal thoracic artery graft flow in the revascularized heart

We investigated the clinical applicability of the transittime ultrasound technique for quantitation of internal thoracic artery (ITA) graft flow in coronary artery bypass grafting. Intraoperative measurements of arterial and venous coronary graft flow were performed in 63 patients using an ultrasonic flowmeter. Native ITA blood flow was determined using a skeletonized segment of the ITA and a flexible perivascular flow probe. Simultaneous measures of ultrasonic blood flow from the proximal part of the ITA and free flow from the distal cut end of the ITA validated reliability. After coronary grafting, separate perivascular flow probes over the saphenous vein and ITA grafts were positioned to measure flows during cardiopulmonary bypass and immediately before the sternal closure. Mean native ITA flow was 7 ± 0.8 mL/min and ITA graft flow was 35 ± 4 mL/min, a fivefold increase after grafting to the coronary artery ( p < 0.001). Mean saphenous vein graft blood flow of 38 ± 4 mL/min was not significantly different from the mean ITA graft flow ( p = 0.37). Coronary blood flow via saphenous vein and ITA conduits was unaffected by the Cardiopulmonary bypass ( p = 0.73). No complications were directly caused by the flow measurements. Flow impedance resulting from pedicle twist at the distal anastomosis was easily detected in 2 patients using the ultrasonic flowmeter. We conclude that ITA graft flow can be quantitated intraoperatively by the transit-time ultrasound technique. Ultrasonic assessment of ITA graft flow in the revascularized heart may be a useful means of detecting immediate coronary graft failure caused by technical errors.

Conditional probability of multiple coronary graft failure

To assess the potential capability of using artery-specific factors to predict the success of coronary bypass grafting, we classified each graft according to the type of graft (mammary, single vein, or multiple skip vein), the degree of obstruction in the native coronary artery, and the size of the grafted artery. The mean patency rates for each category of graft were determined by performing early postoperative (mean 6.6 months) arteriograms in 354 patients. We found that mammary arteries gave the best results for every graft category. Skip vein grafts had a higher mean patency rate than single vein grafts for arteries with obstructions between 70% and 90% and lumina less than 2.0 mm in diameter. The results for vein and skip grafts were equivalent for the category with arteries greater than 2.0 mm and obstruction greater than 90%. Vein grafts produced better results than skip grafts for the remaining categories. Patients were classified into subgroups according to the number of actually observed graft failures. The probabilities that specific numbers of grafts would fail were calculated for each patient. These probabilities were based upon the observed patency rates for the category appropriate for each graft and the hypothesis that individual grafts within a patient fail independently. We observed an excess number of patients with no failures or multiple failures than would be expected according to the hypothesis of independent failure and category-specific patency rates. Conversely, there were fewer patients than expected who had single failures. Therefore, we postulate that there may also be global factors which influence early graft patency.

Reoperation for Coronary Graft Failure: Clinical and Angiographic Results in 43 Patients

Reoperation because of early or late coronary graft failure was performed in 43 patients who were part of a group of 1,985 patients operated on for coronary artery disease and followed for up to 7 years. Considerable variation in the results was noted depending on whether the patients were symptomatic or not before reoperation. Of the symptomatic patients, 85% were asymptomatic late (30 months) after reoperation whereas of those patients reoperated on despite the apparent lack of symptoms, 71.5% remained free from angina later on. Moreover, patency rate was high (94.4% or 17/18 grafts) in the first group and much lower (38.4% or 5/13 grafts) in those reoperated on solely on the basis of an early angiogram showing malfunctioning grafts. Patency rate was higher when the graft was totally replaced (92.3% or 12/13 restudied) rather than repaired simply through interposition of a segment of vein (37.5% or 3/8). It is apparent that results of reoperation in symptomatic patients are identical to those of an initial revascularization. On the other hand, patients who are asymptomatic despite early evidence of malfunctioning grafts should be reoperated on only when optimal angiographic conditions are present, that is, a coronary artery that is a good size, severely narrowed, and supplying a large myocardial area.