Gut ischaemia following cardiac surgery

Incidence and Diagnostic Challenges of Bowel Ischemia after Continuous-flow Left Ventricular Assist Device Therapy

Long-term continuous-flow left ventricular assist device (CFLVAD) therapy is limited by complications. Compared with stroke and renal dysfunction, post-CFLVAD bowel ischemia is poorly characterized. Adult patients who underwent first-time durable CFLVAD implantation at our institution between 2008 and 2018 were identified and screened for bowel ischemia using Current Procedural Terminology codes for abdominal surgical exploration and International Classification of Disease codes for intestinal vascular insufficiency. Patients who developed biopsy-proven bowel ischemia (cases) were matched to controls (1:1, nearest neighbor, caliper = 0.29) based on preoperative characteristics. Incidences of postoperative right heart failure and renal replacement therapy were compared using McNemar's test. One year survival was estimated using the Kaplan-Meier method. Overall, 711 patients underwent CFLVAD implantation. Nineteen (2.7%) developed bowel ischemia (cases) median 17 days postimplantation (IQR 8-71). The majority of cases were male (78.9%), Black (63.2%), received HeartMate II (57.9%), treated as destination therapy (78.9%), and had a history of hypertension (89.5%), chronic kidney disease (84.2%), hyperlipidemia (84.2%), smoking (78.9%), and atrial fibrillation (57.9%). Post-LVAD, case patients were more likely to develop moderate-severe right heart failure (89.5% vs. 68.4%, p = 0.005), require renal replacement therapy (21.1% vs. 0%, p < 0.001), and less likely to survive to discharge (52.6% vs. 89.5%, p = 0.02) compared with controls. Case subjects demonstrated worse 1 year survival. While less common than stroke and renal dysfunction, post-CFLVAD bowel ischemia is associated with high 1 year mortality. Multi-institutional registries should consider reporting abdominal complications such as bowel ischemia as an adverse event to further investigate these trends and identify predictors of this complication to reduce patient mortality.

Predicting outcomes of mesenteric ischemia postcardiac surgery: A systematic review

OBJECTIVE

This systematic review aims to identify predictors of outcomes of mesenteric ischemia in patients following cardiac surgery.

METHODS

A comprehensive literature search was done on EMBASE, PubMed, Ovid MEDLINE, and SCOPUS using keywords relating to bowel ischemia and cardiac surgery. Database search results were screened by at least two authors and 32 articles were selected for inclusion in this review.

RESULTS

Data on 1907 patients were analyzed. The mean age was 70.0 ± 2.99 years and the prevalence of bowel ischemia was 1.74%. Advanced age was a significant risk factor. 63.16% of patients reported were men, and 58.4% of patients died in hospital. There was heterogeneity in the reported significance of the following preoperative risk factors: hypertension, smoking status, type 2 diabetes mellitus, end-stage renal disease, preoperative left ventricular ejection fraction <35%. Cardiopulmonary bypass (CPB) time, preoperative/operative intra-aortic balloon pump (IABP) support, and inotrope usage were significantly associated with the development of mesenteric ischemia; however, other intraoperative factors including the type of cardiac surgery and duration of aortic cross-clamping had varying levels of reported significance. There were discrepancies in the reported significance of leukocytosis and metabolic acidosis (pH <7.3) as postoperative markers. Postoperative vasopressor use, prolonged ventilation time, and elevation in lactate, transaminases, creatinine, and intestinal fatty acid-binding protein (IFABP) levels were found to be strongly associated with bowel ischemia.

CONCLUSION

This systematic review found the strongest associations of mesenteric ischemia postcardiac surgery to be advanced age, CPB time, rise in lactate, transaminases, creatinine, and IFABP. IABP support, vasopressor, and inotrope use as well as prolonged ventilation were strongly linked too.

The role of computed tomography in the diagnostic pathway of acute mesenteric ischemia: a nested case-control study

BACKGROUND

Computed tomography (CT) can be used as the primary screening modality for the evaluation of patients suspected of having acute mesenteric ischemia known to show high sensitivity and specificity rates.

PURPOSE

To prove the value of CT in patients with pathological abdominal findings following cardiac surgery.

MATERIAL AND METHODS

In a retrospective case-control study, 12 different CT scan parameters of patients with or without mesenteric ischemia following cardiac surgery were compared using univariate and logistic regression analyses.

RESULTS

Of 14,176 patients, 133 (0.9%) received an abdominal CT scan during postoperative care due to pathological abdominal findings. Sixty-eight patients were diagnosed with acute mesenteric ischemia. In-hospital mortality was 73.5% for this group. CT parameters with the highest specificity for indicating colonic ischemia were intestinal (99%) or porto-venous (96%) pneumatosis, abnormal contrast medium enhancement (89%), and occlusion of the proximal inferior mesenteric artery (81%). All of those parameters showed low sensitivity levels in the range of 15%-23%. A statistically significant association between acute mesenteric ischemia and CT appearance was obtained for contrast medium enhancement (odds ratio [OR] 12.2, 95% confidence interval [CI] 1.5-99.2) and intestinal pneumatosis (OR 21.0, 95% CI 2.7-165.2) only.

CONCLUSION

The typical CT criteria indicating mesenteric ischemia lose their accuracy in patients under critical clinical conditions. As CT remains the first-line diagnostic imaging modality for abnormal abdominal findings following cardiac surgery, negative signs should not prevent early laparotomy if clinical suspicion remains high.

Detection of patients at high risk for nonocclusive mesenteric ischemia after cardiovascular surgery

Objectives

Nonocclusive mesenteric ischemia (NOMI) is a rare but life-threatening complication after cardiovascular surgery. Early diagnosis and treatment is essential for a chance to cure. The aim of this study is to identify the independent risk factors for NOMI based on the evaluation of 12 cases of NOMI after cardiovascular surgery.

Methods

We retrospectively analyzed 12 patients with NOMI and 674 other patients without NOMI who underwent cardiovascular surgery in our hospital. We reviewed the clinical data on NOMI patients, including their characteristics and the clinical course. In addition, we performed a statistical comparison of each factor from both NOMI and non-NOMI groups to identify the independent risk factors for NOMI.

Results

The median duration between the cardiac surgery and the diagnosis of NOMI was 14.0 (10.3–20.3) days. The in-hospital mortality of NOMI patients was 75.0%. Age (p < 0.05), peripheral arterial disease (p < 0.001), postoperative hemodialysis (p < 0.001), intraaortic balloon pump (p < 0.05), norepinephrine (NOE) > 0.10γ (p < 0.0001), percutaneous cardiopulmonary support (p < 0.001), sepsis (p < 0.05), loss of sinus rhythm (p < 0.05), prolonged ventilation (p < 0.0001), and resternotomy for bleeding (p < 0.05) showed significant differences between NOMI and non-NOMI groups. In the multivariate logistic regression model, prolonged ventilation [odds ratio (OR) = 18.1, p < 0.001] and NOE > 0.10 μg/kg/min (OR = 130.0, p < 0.0001) were detected as independent risk factors for NOMI.

Conclusions

We have identified the risk factors for NOMI based on the evaluation of the 12 cases of NOMI after cardiovascular surgery. This result may be useful in predicting NOMI, which is considered difficult in clinical practice. For the patient with suspected of NOMI who has these risk factors, early CT scan and surgical exploration should be performed without delay.

Advents in the Diagnosis and Management of Ischemic Colitis

BACKGROUND

Ischemic colitis (IC) is a common type of ischemic insult, resulting from decreased arterial blood flow to the colon. This disease can be caused from either atherosclerotic occlusive vascular disease or non-occlusive disease. The aim of this study is to present the diagnostic methodology and management of this severe disease based on current literature.

METHODS

A literature search has been done including articles referring to modern diagnosis and management of IC.

RESULTS

IC is usually a transient disease, but it can also cause gangrene of the colon, requiring emergency surgical exploration. Diagnosis is troublesome and is based on imaging examinations, mainly computerized tomography, which in association with colonoscopy can delineate the distribution pattern and severity of disease.

CONCLUSION

The majority of patients with mild disease have usually complete clinical recovery within a short period. The severe forms of the disease carry high morbidity and mortality rates and prompt surgical intervention is the only way to improve the associated severe prognosis.

Feasibility of measuring superior mesenteric artery blood flow during cardiac surgery under hypothermic cardiopulmonary bypass using transesophageal echocardiography: An observational study

Background:

Abdominal complications being rare but results in high mortality, commonly due to splanchnic organ hypoperfusion during the perioperative period of cardiac surgery. There are no feasible methods to monitor intraoperative superior mesenteric artery blood flow (SMABF). Hence, the aim of this study was to evaluate the feasibility and to measure SMABF using transesophageal echocardiography (TEE) during cardiac surgery under hypothermic cardiopulmonary bypass (CPB).

Methodology:

Thirty-five patients undergoing elective cardiac surgery under CPB were enrolled. Heart rate, mean arterial pressure (MAP), cardiac output (CO), SMABF, superior mesenteric artery (SMA) diameter, superior mesentric artery blood flow over cardiac output (SMA/CO) ratio and arterial blood lactates were recorded at three time intervals. T0: before sternotomy, T1: 30 min after initiation of CPB and T2: after sternal closure.

Results:

SMA was demonstrated in 32 patients. SMABF, SMA diameter, SMA/CO, MAP and CO decreased significantly (P < 0.0001) between T0 and T1, increased significantly (P ≤ 0.001) between T0 and T2. Lactates increased progressively from T0 to T2.

Conclusion:

Study shows that there is decrease in SMABF during CPB and returns to baseline after CPB. Hence, it is feasible to measure SMABF using TEE in patients undergoing cardiac surgery under hypothermic CPB. TEE can be a promising tool in detecting and preventing splanchnic hypoperfusion during perioperative period.

Doxycycline protects human intestinal cells from hypoxia/reoxygenation injury: Implications from an in-vitro hypoxia model

Intestinal ischemia/reperfusion (I/R) injury is a grave clinical emergency and associated with high morbidity and mortality rates. Based on the complex underlying mechanisms, a multimodal pharmacological approach seems necessary to prevent intestinal I/R injury. The antibiotic drug doxycycline, which exhibits a wide range of pleiotropic therapeutic properties, might be a promising candidate for also reducing I/R injury in the intestine. To investigate possible protective effects of doxycycline on intestinal I/R injury, human intestinal CaCo-2 cells were exposed to doxycycline at clinically relevant concentrations. In order to mimic I/R injury, CaCo-2 were thereafter subjected to hypoxia/reoxygenation by using our recently described two-enzyme in-vitro hypoxia model. Investigations of cell morphology, cell damage, apoptosis and hydrogen peroxide formation were performed 24h after the hypoxic insult. Hypoxia/reoxygenation injury resulted in morphological signs of cell damage, elevated LDH concentrations in the respective culture media (P<0.001) and increased protein expression of proapoptotic caspase-3 (P<0.05) in the intestinal cultures. These events were associated with increased levels hydrogen peroxide (P<0.001). Preincubation of CaCo-2 cells with different concentrations of doxycycline (5µM, 10µM, 50µM) reduced the hypoxia induced signs of cell damage and LDH release (P<0.001 for all concentrations). The reduction of cellular damage was associated with a reduced expression of caspase-3 (5µM, P<0.01; 10µM, P<0.01; 50µM, P<0.05), while hydrogen peroxide levels remained unchanged. In summary, doxycycline protects human intestinal cells from hypoxia/reoxygenation injury in-vitro. Further animal and clinical studies are required to prove the protective potential of doxycycline on intestinal I/R injury under in-vivo conditions.

Ischemic Colitis after Cardiac Surgery: Can We Foresee the Threat?

Introduction

Ischemic colitis (IC) remains a great threat after cardiac surgery with use of extracorporeal circulation. We aimed to identify predictive risk factors and influence of early catecholamine therapy for this disease.

Methods

We prospectively collected and analyzed data of 224 patients, who underwent laparotomy due to IC after initial cardiac surgery with use of extracorporeal circulation during 2002 and 2014. For further comparability 58 patients were identified, who underwent bypass surgery, aortic valve replacement or combination of both. Age ±5 years, sex, BMI ± 5, left ventricular function, peripheral arterial disease, diabetes and urgency status were used for match-pair analysis (1:1) to compare outcome and detect predictive risk factors. Highest catecholamine doses during 1 POD were compared for possible predictive potential.

Results

Patients’ baseline characteristics showed no significant differences. In-hospital mortality of the IC group with a mean age of 71 years (14% female) was significantly higher than the control group with a mean age of 70 (14% female) (67% vs. 16%, p<0.001). Despite significantly longer bypass time in the IC group (133 ± 68 vs. 101 ± 42, p = 0.003), cross-clamp time remained comparable (64 ± 33 vs. 56 ± 25 p = 0.150). The majority of the IC group suffered low-output syndrome (71% vs. 14%, p<0.001) leading to significant higher lactate values within first 24h after operation (55 ± 46 mg/dl vs. 31 ± 30 mg/dl, p = 0.002). Logistic regression revealed elevated lactate values to be significant predictor for colectomy during the postoperative course (HR 1.008, CI 95% 1.003–1.014, p = 0.003). However, Receiver Operating Characteristic Curve calculates a cut-off value for lactate of 22.5 mg/dl (sensitivity 73% and specificity 57%). Furthermore, multivariate analysis showed low-output syndrome (HR 4.301, CI 95% 2.108–8.776, p<0.001) and vasopressin therapy (HR 1.108, CI 95% 1.012–1.213, p = 0.027) significantly influencing necessity of laparotomy.

Conclusion

Patients who undergo laparotomy for IC after initial cardiac surgery have a substantial in-hospital mortality risk. Early postoperative catecholamine levels do not influence the development of an IC except vasopressin. Elevated lactate remains merely a vague predictive risk factor.

Acute bowel ischemia after heart operations

Acute bowel ischemia is a perioperative complication that is frequently unrecognized as a cause of death after cardiac surgical procedures, with an in-hospital mortality of 50% to 100%. In recent years, controversy regarding the most appropriate approach to resolve clinical or laboratory suspicion and the limited therapeutic options have led to very little improvement in patient prognosis. This article reviews the related literature examining the actual prevalence, pathophysiologic mechanisms, predisposing factors, diagnostic tests, and therapeutic approaches providing a glance at new promising tools in diagnostic workup.

Acute mesenteric ischemia after cardiac surgery: an analysis of 52 patients

OBJECTIVE

Acute mesenteric ischemia (AMI) is a rare but serious complication after cardiac surgery. The aim of this retrospective study was to evaluate the incidence, outcome, and perioperative risk factors of AMI in the patients undergoing elective cardiac surgery.

METHODS

From January 2005 to May 2013, all patients who underwent cardiac surgery were screened for participation, and patients with registered gastrointestinal complications were retrospectively reviewed. Univariate analyses were performed.

RESULTS

The study included 6013 patients, of which 52 (0.86%) patients suffered from AMI, 35 (67%) of whom died. The control group (150 patients) was randomly chosen from among cases undergoing cardiopulmonary bypass (CPB). Preoperative parameters including age (P = 0.03), renal insufficiency (P = 0.004), peripheral vascular disease (P = 0.04), preoperative inotropic support (P < 0.001), poor left ventricular ejection fraction (P = 0.002), cardiogenic shock (P = 0.003), and preoperative intra-aortic balloon pump (IABP) support (P = 0.05) revealed significantly higher levels in the AMI group. Among intra- and postoperative parameters, CPB time (P < 0.001), dialysis (P = 0.04), inotropic support (P = 0.007), prolonged ventilator time (P < 0.001), and IABP support (P = 0.007) appeared significantly higher in the AMI group than the control group.

CONCLUSIONS

Prompt diagnosis and early treatment should be initiated as early as possible in any patient suspected of AMI, leading to dramatic reduction in the mortality rate.

Intestinal ischemia after cardiac surgery: analysis of a large registry

Background

Intestinal ischemia after cardiac surgery is a rare but severe complication with a high mortality. Early surgery can be lifesaving. The aim was to analyze the incidence, outcome, and risk factors for these patients.

Methods

A prospectively collected database with patients who underwent 18,879 cardiac surgical procedures between 1996 and 2011 was investigated. All patients with registered gastrointestinal complications were retrospectively reviewed. Univariate and multivariate analyses were performed to compare patients with and without intestinal ischemia.

Results

Seventeen patients suffered from intestinal ischemia (0.09%), 10 of whom (59%) died. By investigating preoperative parameters independent risk factors were steroids, peripheral vascular disease, cardiogenic shock, and New York Heart Association class 4. When including pre-, per-, and postoperative parameters, only postoperative ones were significant, including elevated creatinine (> 200 μmol/L), prolonged ventilator time, need for intra-aortic balloon pump, and cerebrovascular insult (CVI). The gastrointestinal complications score (GICS) showed a ROC area of 0.87. This was superior compared with EuroSCORE (0.74), to predict intestinal ischemia.

Conclusions

Intestinal ischemia after cardiac surgery is more common in patients with a poor cardiac state, but the use of steroids, peripheral vascular disease, postoperative kidney failure, and CVI were also predictive. GICS score, developed for all GI complications after cardiac surgery, is also of value in predicting this particular complication. The risk factors presented can be used as an aid in the diagnosis of these patients.

Gastrointestinal complications after open heart surgery: incidence and determinants of risk factors

Acute mesenteric ischemia is a rare but serious complication of open heart surgery. Between January 2009 and January 2012, 1360 adult patients underwent open heart surgery with cardiopulmonary bypass at our institution; 29 patients presented gastrointestinal complications. Eight patients developed acute mesenteric ischemia and all of them died. Significant predictors of the complication were New York Heart Association functional class III/IV, history of extensive atherosclerosis and chronic renal failure, acute renal failure following surgery, low cardiac output, use of 2 or more vasoconstrictor drugs, prolonged mechanical ventilation, and multiorgan failure. Atherosclerosis is a multisystemic disease that affects several organs. Radiologic evaluation of mesenteric arterial system should be performed in high-risk patient populations. Perioperative percutaneous and open vascular procedures will reduce the risk of acute mesenteric ischemia that may develop after cardiac surgery and consequent morbidity and mortality rates.

Outcome and survival analysis of intestinal ischaemia following cardiac surgery

OBJECTIVES

Intestinal ischaemia is an uncommon (<1%) but serious complication of cardiac surgery with a mortality rate exceeding 50%. Diagnosis of this potentially lethal condition can be difficult and requires a high index of suspicion. The purpose of this study was to analyse the outcomes and prognostic factors in patients who develop intestinal ischaemia following cardiac surgery.

METHODS

In a retrospective review from August 1999 to December 2010, we identified 31 out of 9925 (0.31%) consecutive patients who developed acute intestinal ischaemia following cardiac surgery at our tertiary centre.

RESULTS

The overall mortality was 71.0%. The operative mortality was 65.4% in patients who underwent a laparotomy. Survivors of this complication had surgical intervention earlier (7.4 ± 4.9 h) compared with the non-survivors (13.9 ± 11.1 h). A total of 35 perioperative variables were analysed. A univariate analysis identified 12 variables associated with an increased risk of mortality. Logistic multivariate analysis identified the preoperative logistic EuroSCORE and the base excess at the point of diagnosis of intestinal ischaemia as significant predictors of mortality. These factors may aid prognostication in this group of patients.

CONCLUSIONS

Despite the high mortality rates associated with intestinal ischaemia following cardiac surgery, early diagnosis and surgical intervention remain the only effective means to reduce mortality.

Risk factors for gastrointestinal complications in patients undergoing coronary artery bypass graft surgery

OBJECTIVE

To determine the risk factors for the development of gastrointestinal complications (GICs) after coronary artery bypass graft (CABG) surgery.

DESIGN

A single-center, retrospective study.

SETTING

A tertiary care hospital.

PARTICIPANTS

Six thousand seven hundred ninety-four patients undergoing isolated CABG surgery between 2002 and 2006.

INTERVENTIONS

Clinical characteristics of the patients with GICs and control group patients were analyzed by stepwise logistic regression analysis. The control group consisted of a total of 95 patients randomly selected among the ones who had no gastrointestinal finding or symptoms (cohort: control, 1:5 ratio).

MEASUREMENTS AND MAIN RESULTS

Nineteen patients (0.3%) developed major surgical GICs after CABG surgery. Overall, the 30-day mortality was 42.1% among patients with GICs and 2.6% without GICs. Multivariate analysis identified 4 independent predictors for GICs: age greater than 70 years (p = 0.001; odds ratio [OR] = 5.6; 95% confidence interval [CI], 2.1-25.9), reoperation for bleeding (p = 0.005; OR = 7.7; 95% CI, 2.8-56.2), a prolonged cardiopulmonary bypass time (p = 0.007; OR = 3.7; 95% CI, 1.3-15.6), and an increased postoperative creatinine level (p = 0.036; OR = 2.3; 95% CI, 1.1-13.4).

CONCLUSION

A delayed diagnosis of complications is an important problem in the management of major surgical GICs. The present results suggest that surgeons and intensivists must be alert to patients older than 70 years, a cardiopulmonary bypass time longer than 60 minutes, reoperation for bleeding after CABG surgery, and postoperative creatinine level higher than 1.7 mg/dL.

Acute mesenteric ischemia after cardio-pulmonary bypass surgery

Acute mesenteric ischemia (AMI) is a highly-lethal surgical emergency. Several pathophysiologic events (arterial obstruction, venous thrombosis and diffuse vasospasm) lead to a sudden decrease in mesenteric blood flow. Ischemia/reperfusion syndrome of the intestine is responsible for systemic abnormalities, leading to multi-organ failure and death. Early diagnosis is difficult because the clinical presentation is subtle, and the biological and radiological diagnostic tools lack sensitivity and specificity. Therapeutic options vary from conservative resuscitation, medical treatment, endovascular techniques and surgical resection and revascularization. A high index of suspicion is required for diagnosis, and prompt treatment is the only hope of reducing the mortality rate. Studies are in progress to provide more accurate diagnostic tools for early diagnosis. AMI can complicate the post-operative course of patients following cardio-pulmonary bypass (CPB). Several factors contribute to the systemic hypo-perfusion state, which is the most frequent pathophysiologic event. In this particular setting, the clinical presentation of AMI can be misleading, while the laboratory and radiological diagnostic tests often produce inconclusive results. The management strategies are controversial, but early treatment is critical for saving lives. Based on the experience of our team, we consider prompt exploratory laparotomy, irrespective of the results of the diagnostic tests, is the only way to provide objective assessment and adequate treatment, leading to dramatic reduction in the mortality rate.