Comparison of parameters for detection of splanchnic hypoxia in children undergoing cardiopulmonary bypass with pulsatile versus nonpulsatile normothermia or hypothermia during congenital heart surgeries

The aim of this study is to evaluate gastric mucosal oxygenation together with whole-body oxygen changes in infants undergoing congenital heart surgery with cardiopulmonary bypass (CPB) procedure and the use of either pulsatile or nonpulsatile mode of perfusion with normothermia and pulsatile or nonpulsatile moderate hypothermia. Sixty infants undergoing congenital cardiac surgery were randomized into four groups as: nonpulsatile normothermia CPB (NNCPB, n = 15), pulsatile normothermia CPB (PNCPB, n = 15), nonpulsatile moderate hypothermia CPB (NHCPB, n = 15), and pulsatile moderate hypothermia CPB (PHCPB, n = 15) groups. In NNCPB and PNCPB groups, mild hypothermia was used (35°C), whereas in NHCPB and PHCPB groups, moderate hypothermia (28°C) was used. Gastric intramucosal pH (pHi), whole-body oxygen delivery (DO(2)) and consumption (VO(2)), and whole-body oxygen extraction fraction were measured at sequential time points intraoperatively and up to 2 h postoperatively. The measurement of continuous tonometry data was collected at desired intervals. The values of DO(2), VO(2), and whole-body oxygen extraction fraction were not different between groups before CPB and during CPB, whereas the PNCPB group showed higher values of DO(2), VO(2), and whole-body oxygen extraction fraction compared to the other groups at the measurement levels of 20 and 60 min after aortic cross clamp, end of CPB, and 2 h after CPB (P < 0.0001). Between groups, no difference was observed for pHi, lactate, and cardiac index values (P > 0.05). This study shows that the use of normothermic pulsatile perfusion (35°C) provides better gastric mucosal oxygenation as compared to other perfusion strategies in neonates and infants undergoing congenital heart surgery with CPB procedures.     

Myocardial Revascularization of the Beating Heart in High-Risk Patients

OBJECTIVE: Myocardial revascularization without cardiopulmonary bypass (CPB) has been proposed as an alternative technique in patients at high risk for conventional coronary artery bypass grafting (CABG). The purpose of this article is to evaluate the potential benefit of such an approach. METHODS: We retrospectively evaluated the perioperative results of off-pump CABG (OPCAB) performed from January 1995 to December 1999. Patients were divided into three groups on the basis of their preoperative risk factors: age greater than 80 years, reoperative CABG, and left ventricular ejection fraction percentage (LVEF%) less than 40%. The three subgroups were compared with patients operated on-CPB (ONCAB) during the same period of time. A total of 172 octogenarians had ONCAB versus 97 OPCAB, 307 reoperations were ONCAB versus 274 OPCAB, and 514 patients with LVEF% less than 40% were operated ONCAB versus 220 OPCAB. RESULTS: Preoperative comorbidities were homogeneously distributed in the OPCAB and ONCAB groups. More extensive coronary artery disease was found in the ONCAB groups. A trend for a lower number of perioperative complications was reported in the OPCAB groups. Freedom from overall complications was significantly higher (p < 0.005) in the OPCAB group. Actual mortality rates in the OPCAB and ONCAB groups were comparable (p = NS). CONCLUSIONS: CABG can be performed safely without CPB in patients with a high preoperative risk profile. Freedom from perioperative complications is markedly higher when the OPCAB approach is utilized.     

Pre- and postoperative exercise capacity associated with hemodynamics in adult patients with atrial septal defect: A retrospective study

Objective: This study evaluated the pre- and postoperative exercise capacity in adult patients with atrial septal defect (ASD) associated with hemodynamic variables. Methods: Adults (70) with ASD underwent symptom-limited exercise tests. Peak O₂ uptake (Peak VO₂) and % peak VO₂, that is the percentage of predicted value, were measured. These patients were divided into three groups according to pulmonary-to-systemic flow ratio (Qp/Qs) and systolic pulmonary arterial pressure (PAs); Group A: Qp/Qs3, PAs50 mm Hg, Group B: Qp/Qs>3, any PAs, Group C: Qp/Qs3, PAs>50 mm Hg. Exercise test was repeated in 22 patients after surgical closure of ASD (mean 4.6±2.0 months). Results: Peak VO₂ was significantly lower in group B (P<0.01) and group C (P<0.01) than in group A (19.3±5.7, 17.6±3.6, 27.6±6.3 ml/min/kg, respectively). In patients except those in group C, there were a weak negative correlation between PAs and % peak VO₂ (r=0.61) and a significant negative correlation between Qp/Qs and % peak VO₂ (r=0.86). Postoperative peak VO₂ increased significantly in group A (27.2±5.1–31.1±5.1 ml/min/kg, P<0.05) and group B (16.7±3.3–21.5±2.1 ml/min/kg, P<0.01). However, there was no significant difference between pre- and postoperafive peak VO₂ in group C (16.8±1.3–17.8±2.8 ml/min/kg, NS). Conclusions: In ASD patients except those with small or moderate left-to-right shunt and high pulmonary arterial pressure, there was a significant negative correlafion between Qp/Qs and peak VO₂ corrected by age and gender. Patients with large left-to-right shunt and/or high pulmonary arterial pressure had reduced exercise capacity. However, exercise capacity in patients with large left-to-right shunt increased after closure of ASD regardless of whether they had high pulmonary arterial pressure.     

The clinical outcome of off-pump coronary artery bypass surgery in the elderly patients

Objective: There has been a body of evidence showing that off-pump coronary artery bypass (OPCAB) may reduce morbidity and mortality in the elderly patients. We reviewed our experience, retrospectively, on elderly patients aged 75 years and older who were operated on using the OPCAB technique. We compared their outcome to a similar group of elderly patients who were operated on using conventional coronary artery bypass grafting (CABG) with cardiopulmonary bypass (CPB) during the same period of time. Methods: Registry data and patients' notes and charts were reviewed for 56 consecutive elderly OPCAB patients (age 78.5±3.5 years) and 87 consecutive CPB patients (age 77.2±2.4 years, P=0.01). Both groups had similar risk factor profiles: Parsonnet score 17.4±4.4 (OPCAB) versus 16.6±5.2 (CPB), P=0.19. We studied in detail their preoperative and postoperative data in order to compare the outcomes of both techniques. Results: The length of stay in the intensive therapy unit (ITU) was 35.4±52.9 h for OPCAB patients and 77.6±144.9 h for CPB patients (P=0.0008). No patient died within 30 days in the OPCAB group, whilst ten (11%) CPB patients (P=0.0066) died within 30 days. The incidence of serious complications (including pulmonary oedema, septicaemia, permanent stroke and renal dysfunction requiring haemofiltration or haemodialysis) was one (2%) in the OPCAB group and 11 (13%) in the CPB group (P=0.028). CPB patients required a significantly higher number ten (12%) of intra-aortic balloon pumps (IABP) inserted compared to only one patient (2%) in the OPCAB group who required IABP insertion (P=0.05). Nine (11%) CPB patients were re-operated on for bleeding compared to no OPCAB patient (0%) needing re-operation, P=0.011. Conclusions: Although the mean age of the OPCAB group was significantly higher than the CPB group, the OPCAB group showed a significant reduction in postoperative serious morbidity, ITU stay and mortality. We believe that such a conclusion may have some effect on the decision-making and cost-effectiveness when performing coronary bypass surgery on the elderly population.     

On-pump beating heart versus off-pump coronary artery bypass surgery—evidence of pump-induced myocardial injury

Objective: By maintaining native coronary blood flow in on-pump beating heart surgery (OnP-BH) and comparing with OPCAB strategy pump-related effects on myocardial injury and cardiac dysfunction could be specifically differentiated from ischemia/reperfusion-related consequences of surgical coronary revascularization. Methods: In a randomized-prospective design, 40 elective patients with normal EF and three vessels coronary artery disease (left main disease excluded) were assigned to OPCAB or OnP-BH surgery. Before coronary occlusion and 1, 30, 60, and 90 min after reperfusion with the LIMA graft, coronary sinus (CS) blood was sampled to determine intraoperative myocardial ischemia (pH, lactate, pO₂) and oxidative stress (malondialdehyde, MDA). Additionally to CS blood arterial blood was analyzed 4, 12, and 24 h postoperatively to determine myocardial necrosis (CK-MB, cardiac troponin I), myocardial dysfunction (NT-proBNP) and inflammation (C-reactive protein). Results: Groups were identical with regards to age and gender (OPCAB 63.0±6.0 versus OnP-BH 65.3±3.9 y, 20% female patients). Number of grafts were 3.0±0.5 in OPCAB versus 2.9±0.3 in OnP-BH (n.s.) with 44 versus 34% bilateral IMAs and 56 versus 50% complete arterial revascularization. Regarding ischemia, intraoperatively only lactate values increased significantly in the OnP-BH group. Significantly higher CK-MB and troponin I levels were found from LIMA-LAD flow release onwards to 4 h postoperatively in the OnP-BH group. NT-proBNP levels were significantly higher in the OnP-BH group during the entire study period. CRP levels were higher in the OnP-BH group 12 and 24 h postoperatively. Conclusions: In this randomized study on routine coronary patients with normal ventricular function, OPCAB revealed less myocardial injury than OnP-BH. These findings implicate that CPB slightly affects the myocardium.     

The effect of respiratory alkalosis on oxygen consumption in anesthetized patients

Study Objective: To investigate whether hyperventilation significantly altered oxygen consumption in anesthetized and paralyzed patients undergoing surgery.

Design: Open crossover trial with 1 hour of hyperventilation preceded and followed by 1 hour of normoventilation.

Setting: University medical center.

Patients: Eight patients (five men and three women) undergoing lengthy orthopedic surgery with general anesthesia and muscle paralysis.

Interventions: After baseline normoventilationfor 1 hour (Period 1), the anesthetized patients were hyperventilated to an arterial carbon dioxide tension (PaCO₂) of 20 to 25 mmHg for 1 hour (Period 2). Patients then experienced another hour of normoventilation (Period 5).

Measurements and Main Results: Hemodynamic variables, electrocardiography, temperature, end-tidal partial pressure of CO₂ (P_ETCO₂), oxygen consumption (VO₂), carbon dioxide production, and minute ventilation were continuously followed throughout the study, and arterial blood gases were drawn at the beginning and end of each study period. During the period of hyperventilation, pH was significantly higher and P._ETCO₂ and (PaCO₂) significantly lower compared with the periods of normoventilation. (VO₂), was significantly increased during hyperventilation compared with the periods of normoventilation. Hemodynamic variables and temperature were similar in the three study periods.

Conclusions: In anesthetized paralyzed patients, there is an increase in whole-body (VO₂), with hypocapnic alkalosis.     

Effect of hemofiltrated whole blood pump priming on hemodynamics and respiratory function after the arterial switch operation in neonates

Background. Primed blood might have some deleterious effects on neonates during cardiopulmonary bypass (CPB) due to unbalanced electrolytes and inflammatory mediators. We hemofiltrated pump-primed blood before CPB to reduce inflammatory mediators and to adjust pH and the concentrations of electrolytes. The current study investigated the effects of hemofiltrated whole blood priming on hemodynamics and respiratory function after CPB in neonates.

Methods. Patients who underwent the arterial switch operation in the neonatal period for transposition of the great arteries with intact ventricular septum were chosen for this study. Seventeen patients underwent CPB with hemofiltrated blood priming (group HF) and 23 patients underwent CPB with nonhemofiltrated blood priming (group N). The concentrations of electrolytes and bradykinin and high molecular weight kininogen of the primed blood before and after hemofiltration were measured. At 4 hours after completion of CPB, the left ventricular percent fractional shortening, and the relation between the mean velocity of shortening and the end-systolic wall stress (stress velocity index), were measured by echocardiogram in 7 patients in group HF and 6 patients in group N. Alveolar − arterial oxygen tension difference (AaDO₂) and respiratory index (AaDO₂ divided by arterial oxygen tension) were measured at several points for 48 hours after CPB in all patients.

Results. Hemofiltration of the primed blood maintained electrolytes within a physiologic level and significantly reduced the concentrations of bradykinin (5,649 ± 1,353 pg/mL versus 510 ± 35 pg/mL, p < 0.05) and high molecular weight kininogen (52.7% ± 3.2% versus 40.1% ± 3.0% of normal plasma value, p < 0.05). The percent of fractional shortening at 4 hours after completion of CPB was significantly higher in group HF (n = 7) than in group N (n = 6) (22.0% ± 0.7% versus 16.0% ± 0.4%, p < 0.01). There was also a trend toward better stress velocity index in group HF than in group N (0.81 ± 0.81 versus −2.17 ± 0.45, p = 0.09). AaDO₂ and respiratory index were significantly lower in group HF than in group N for 48 hours after CPB, respectively (p < 0.05).

Conclusions. Hemofiltrated fresh whole blood used for CPB priming attenuated cardiac impairment at early reperfusion periods and reduced pulmonary dysfunction in neonates with transposition of the great arteries with intact ventricular septum. This therapeutic strategy may have an advantage in preventing lung and heart dysfunction in pediatric patients who need CPB priming with blood.     

Mitral valve repair by Alfieri''s technique does not limit exercise tolerance more than Carpentier''s correction

Objective: The main goal of this study was to evaluate if the edge-to-edge mitral repair could be a limiting factor for exercise tolerance and to compare these results to those of classical techniques. Methods: Between 2000 and 2002, 54 consecutive patients were operated on for mitral valve regurgitation (MR). Twenty-five patients were operated with Alfieri's technique (group A) and 29 patients with Carpentier's technique (group C). The mean age was 63.9 years in group A and 63.8 years in group C (p = 0.98). After a mean follow-up of 16.2 ± 12 months, survivor patients were seen at the outpatient clinic, by the same physician for a clinical evaluation, an echocardiogram at rest and at peak exercise, and received a cardiorespiratory exercise testing with maximal oxygen uptake (VO₂ max) recording. Results: Clinical status improved with 0% of the patients in class NYHA III or IV in either group postoperatively versus 77% preoperatively. There was no significant MR in 80% of cases in group A versus 89.6% in group C (p = 0.54). The mean mitral valve area was 2.5 and 2.9 cm² in groups A and C, respectively (p = 0.018). The mitral gradient at rest was 3.8 and 3.3 mmHg (p = 0.31) and the mitral gradient at peak exercise was 8.5 and 9.7 mmHg (p = 0.22) in groups A and C, respectively. Cardiorespiratory exercise testing showed a mean VO₂ max of 73.7 ± 15% of normal value in group A versus 79.6 ± 13.1% in group C (p = 0.18). Conclusion: Alfieri's technique has the same efficiency on improvement of MR and clinical status than classical repair. Despite a higher restriction of mitral valve area at rest in group A, gradient and mean VO₂ max at peak exercise were similar in both groups.     

Dopexamine and dopamine in the prevention of low gastric mucosal pH following cardiopulmonary by-pass

The effect of low-dose dopexamine and dopamine on gastric intramucosal pH (pH_i) during cardiac surgery and 16 hours postoperatively was studied in 35 adult patients (coronary artery bypass grafting and/or valve replacement). The patients were assigned randomly to treatment groups with either dopexamine 1 μg. kg^-1.min^-1 (n=12), dopamine 2.5 μg. kg^-1.min^-1 (n=11) or to a control group (n=12). The infusions were started after induction of anesthesia and were continued until 16 hours after CPB. pH_i and arterial pH (pH_a) did not differ between groups and remained unchanged during cardiopulmonary by-pass and for the first four postoperative hours. Both the carbon dioxide tension of arterial blood (P_aCO₂) and of the saline in the tonometer (P_tonCO₂) changed in parallel with a decrease during CPB and an increase after CPB and surgery with maximal values 12 hours after termination of CPB. A significant correlation was noted between pH_i and pH_a and between arterial and tonometric PCO₂. It is concluded that low dose dopexamine and dopamine have no influence on pH_i during and after cardiac surgery. The observed changes in pH_i and P_tonCO₂ were due to changes in pH_a and in P_aCO₂ and not a sign of gastric mucosal ischemia     

Intraaortic balloon pump therapy facilitates posterior vessel off-pump coronary artery bypass grafting in high-risk patients

Background. Displacement of the heart to expose posterior vessels during coronary artery bypass grafting (CABG) without cardiopulmonary bypass (off-pump CABG, or OPCAB) may impair cardiac function. We used the intraaortic balloon pump (IABP) preoperatively to reduce operative risk and to facilitate posterior vessel OPCAB in high-risk patients with left main coronary artery disease (> 75% stenosis), intractable resting angina, postinfarction angina, left ventricular dysfunction (ejection fraction < 35%), or unstable angina.

Methods. One hundred and forty-two consecutive patients who underwent multivessel OPCAB including posterior vessel revascularization were studied prospectively. The patients were divided into group I (n = 57), which received preoperative or intraoperative IABP, and group II (n = 85), which did not receive IABP. In group I, there were 34 patients with left main coronary artery disease, 24 patients with intractable resting angina, 8 patients with left ventricular dysfunction, 5 patients with postinfarction angina, and 40 patients with unstable angina. Seven patients received intraoperative IABP support owing to hemodynamic instability during OPCAB.

Results. There was no operative mortality in group I and 1 death in group II. The average number of distal anastomoses was not different between group I and group II (3.4 ± 0.9 versus 3.5 ± 0.9, p = not significant). There were no significant differences in the number of posterior vessel anastomoses per patient. There were no differences in ventilator support time, length of stay in the intensive care unit, hospital stay, and morbidity between the two groups. There was one IABP-related complication in group I.

Conclusions. IABP therapy facilitates posterior vessel OPCAB in high-risk patients, and surgical results are comparable with those in lower-risk patients.     

Inflammatory response and myocardial injury following coronary artery bypass grafting with or without cardiopulmonary bypass

Objective: In coronary artery bypass grafting (CABG) without cardiopulmonary bypass (CPB) the inflammatory response is suggested to be minimized. Coronary anastomoses are performed during temporary coronary occlusion. Inflammatory response and myocardial ischaemia need to be studied in a randomized study comparing CABG in multivessel disease with versus without CPB. Methods: Following randomization 30 consecutive patients received CABG either with (n=16) or without CPB (n=14). Primary study endpoints were parameters of the inflammatory response (interleukin (IL)-6, interleukin-10, ICAM-1, P-selectin) and of myocardial injury (myoglobin, creatine kinase-MB (CK-MB), troponin I) (intraoperatively, 4, 8, 16, 24 and 48 h after surgery). The secondary endpoint was clinical outcome. Results: The incidence of major (death: CABG with CPB n=1, not significant (n.s.)) and minor adverse events (wound infection: with CPB n=2, without CPB n=1, n.s.; atrial fibrillation: with CPB n=3, without CPB n=2, n.s.) was comparable between both groups. The release of IL-6 was comparable during 8 h of observation (n.s.). Immediately postoperatively IL-10 levels were higher in the operated group with CPB (211.7±181.9 ng/ml) than in operated patients without CPB (104.6±40.3 ng/ml, P=0.0017). Thereafter no differences were found between both groups. A similar pattern of release was observed in serial measures of ICAM-1 and P-selectin, with no difference between both study groups (n.s.). Eight hours postoperatively the cumulative release of myoglobin was lower in operated patients without CPB (1829.7±1374.5 μg/l) than in operated patients with CPB (4469.8±4525.7 μg/l, P=0.0152). Troponin I release was 300.7±470.5 μg/l (48 h postoperatively) in patients without CPB and 552.9±527.8 μg/l (P=0.0213). CK-MB mass release was 323.5±221.2 μg/l (24 h postoperatively) in operated patients without CPB and 1030.4±1410.3 μg/l in operated patients with CPB (P=0.0003). Conclusions: This prospective randomized study suggests that in low-risk patients the impact of surgical access on inflammatory response may mimic the influence of long cross-clamp and perfusion times on inflammatory response. Our findings indicate that multiregional warm ischaemia, caused by snaring of the diseased coronary artery, causes considerably less myocardial injury than global cold ischaemia induced by cardioplegic cardiac arrest.     

Does sodium nitroprusside reduce lung injury under cardiopulmonary bypass?

Objective: We hypothesized that direct pulmonary arterial infusion of sodium nitroprusside (SNP) would ameliorate lung injury under cardiopulmonary bypass. Methods: Experiments were performed on 12 adult mongrel dogs of both sexes weighing 20–28 kg. The animals were randomly divided into two groups of six animals each. All animals were subjected to total cardiopulmonary bypass (CPB) and moderate hypothermia (28°C core temperature). During total CPB, the aorta was clamped together with the pulmonary artery to prevent any antegrade flow to the lungs. After cardioplegic arrest for 120 min, the animals were rewarmed, weaned from CPB, and their condition stabilized for another 90 min. After the release of the aortic cross-clamp, the dogs received either a 5% glucose solution as a placebo (group I) or SNP (0.5 μg/kg per min) (group II), both infused into the pulmonary arterial line. The infusion was stopped after 60 min. To measure lung tissue malondialdehyde (MDA), water content and polymorphonuclear leukocytes count, lung tissue samples were taken before CPB and after weaning from CPB. In addition, alveolar-arterial oxygen difference (AaDO₂) for tissue oxygenation was calculated by obtaining arterial blood gas samples. Results: Values of MDA before CPB of 42.0±5.3 nmol/g of tissue rose to 67.6±5.7 nmol/g of tissue after weaning from CPB in group I (P=0.028). In group II MDA values also increased from 43.1±4.3 to 52.4±5.7 nmol MDA/g of tissue after weaning from CPB (P=0.046). The MDA increase in group II after CPB was found to be significantly lower than that for group I (P=0.004). The wet-to-dry lung weight ratio in the sodium nitroprusside group was 5.1±0.2, significantly lower than in the control group (6.8±0.4), (P=0.01). AaDO₂ increased significantly in group I (P=0.028). There was no statistically significant difference (P=0.065) between groups I and II. During histopathological examination it was observed that neutrophil counts in the lung parenchyma rose significantly after CPB in both groups. The increase in group I was significantly larger than that in group II (P<0.001). Conclusions: The results represented in our study indicate that pulmonary arterial infusion of sodium nitroprusside during reperfusion can reduce lung injury under cardiopulmonary bypass.     

Excimer versus carbon dioxide transmyocardial laser revascularization: effects on regional left ventricular function and perfusion

Background. Transmyocardial laser revascularization (TMR) has been established with the carbon dioxide (CO₂) laser. The largely unstudied excimer laser creates channels through chemical bond dissociation instead of thermal ablation, thereby avoiding thermal injury. We sought to compare the effects of CO₂ and excimer TMR in a porcine model of chronic ischemia.

Methods. Pigs underwent ameroid constrictor placement on the circumflex artery to create chronic ischemia. TMR was performed with CO₂ (n = 8) or excimer (n = 8) laser 6 weeks later; controls (n = 7) had ameroid placement only. Regional myocardial blood flow (RMBF), determined by radioactive microspheres, and regional myocardial function, determined by percent segmental shortening (%SS), were assessed 18 weeks after ameroid placement.

Results. Values are mean ± SD. In the ischemic zone, RMBF (mL/min/g) was improved in the CO₂ (0.73 ± 0.19) and excimer (0.78 ± 0.22) groups when compared with controls (0.55% ± 0.12%, p < 0.05). %SS was also improved in the CO₂ (15.2% ± 5.5%) and excimer (15.3% ± 5.1%) groups when compared with controls (8.0% ± 4.2%, p < 0.05).

Conclusions. Excimer and CO₂ TMR significantly improve RMBF and regional function in this porcine model of chronic myocardial ischemia despite fundamentally different tissue interactions.     

Risk-adjusted analysis of long-term outcomes after on- versus off-pump coronary artery bypass grafting

 Open in a separate windowOBJECTIVESRecent data suggested that off-pump coronary artery bypass (OPCAB) may carry a higher risk for mortality in the long term when compared to on-pump coronary artery bypass (ONCAB). We, therefore, compared long-term survival and morbidity in patients undergoing ONCAB versus OPCAB in a large single-centre cohort.METHODSA total of 8981 patients undergoing isolated elective/urgent coronary artery bypass grafting between January 2009 and December 2019 were analysed. Patients were stratified into 2 groups (OPCAB n = 6649/ONCAB n = 2332). The primary end point was all-cause mortality. Secondary endpoints included repeat revascularization, stroke and myocardial infarction. To adjust for potential selection bias, 1:1 nearest neighbour propensity score (PS) matching was performed resulting in 1857 matched pairs. Moreover, sensitivity analysis was applied in the entire study cohort using multivariable- and PS-adjusted Cox regression analysis.RESULTSIn the PS-matched cohort, 10-year mortality was similar between study groups [OPCAB 36.4% vs ONCAB 35.8%: hazard ratio (HR) 0.99, 95% confidence interval (CI) 0.87–1.12; P = 0.84]. While 10-year outcomes of secondary endpoints did not differ significantly, risk of stroke (OPCAB 1.50% vs ONCAB 2.8%: HR 0.51, 95% CI 0.32–0.83; P = 0.006) and mortality (OPCAB 3.1% vs ONCAB 4.8%: HR 0.65, 95% CI 0.47–0.91; P = 0.011) at 1 year was lower in the OPCAB group. In the multivariable- and the PS-adjusted model, mortality at 10 years was not significantly different (OPCAB 34.1% vs ONCAB 35.7%: HR 0.97, 95% CI 0.87–1.08; P = 0.59 and HR 1.01, 95% CI 0.90–1.13; P = 0.91, respectively).CONCLUSIONSData do not provide evidence that elective/urgent OPCAB is associated with significantly higher risks of mortality, repeat revascularization, or myocardial infarction during late follow-up when compared to ONCAB. Patients undergoing OPCAB may benefit from reduced risks of stroke and mortality within the first year postoperatively.     

A prospective randomized study to evaluate the renoprotective action of beating heart coronary surgery in low risk patients.

OBJECTIVES: Cardiopulmonary bypass (CPB) is widely regarded as an important contributor to renal failure, a well recognized complication following coronary artery surgery (coronary artery bypass grafting (CABG)). Anecdotally off-pump coronary surgery (OPCAB) is considered renoprotective. We examine the extent of renal glomerular and tubular injury in low-risk patients undergoing either OPCAB or on-pump coronary artery bypass (ONCAB). METHODS: Forty low-risk patients with normal preoperative cardiac and renal functions awaiting elective CABG were prospectively randomized into those undergoing OPCAB (n=20) and ONCAB (n=20). Glomerular and tubular injury were measured respectively by urinary excretion of microalbumin and retinol binding protein (RBP) indexed to creatinine (Cr). Daily measurements were taken from admission to postoperative day 5. Fluid balance, serum Cr and blood urea were also monitored. RESULTS: No mortality or renal complication were observed. Both groups had similar demographic makeup, Parsonnet score, functional status and extent of coronary revascularization (2.1+/-1.0 vs. 2.5+/-0.7 grafts; P=0.08). Serum Cr and blood urea remained normal in both groups throughout the study. A significant and similar rise in urinary RBP:Cr occurred in both groups peaking on day 1 (3183+/-2534 vs. 4035+/-4079; P=0.43) before reapproximating baseline levels. These trends were also observed with urinary microalbumin:Cr (5.05+/-2.66 vs. 6.77+/-5.76; P=0.22). Group B patients had a significantly more negative fluid balance on postoperative day 2 (-183+/-1118 vs. 637+/-847 ml; P=0.03). CONCLUSIONS: Although renal complication or serum markers of kidney dysfunction were absent, sensitive indicators revealed significant and similar injury to renal tubules and glomeruli following either OPCAB or ONCAB. These results suggest that avoidance of CPB does not offer additional renoprotection to patients at low risk of perioperative renal insult during CABG.     

Beating‐Heart Coronary Artery Bypass Grafting With Miniaturized Cardiopulmonary Bypass Results in a More Complete Revascularization When Compared to Off‐Pump Grafting

The technique of miniaturized cardiopulmonary bypass (M‐CPB) for beating‐heart coronary artery bypass grafting (CABG) is relatively new and has potential advantages when compared to conventional cardiopulmonary bypass (CPB). M‐CPB consists of less tubing length and requires less priming volume. The system is phosphorylcholine coated and results in minimal pump‐related inflammatory response and organ injury. Finally, this technique combines the advantages of the off‐pump CABG (OPCAB) with the better exposure provided by CPB to facilitate complete revascularization. The hypothesis is that CABG with M‐CPB has a better outcome in terms of complete coronary revascularization and perioperative results as that compared to off‐pump CABG (OPCAB). In a retrospective study, 302 patients underwent beating‐heart CABG, 117 (39%) of them with the use of M‐CPB and 185 (61%) with OPCAB. After propensity score matching 62 patients in both groups were demographically similar. The most important intra‐ and early‐postoperative parameters were analyzed. Endpoints were hospital mortality and complete revascularization. Hospital mortality was comparable between the groups. The revascularization was significantly more complete in M‐CPB patients than in patients in the OPCAB group. Beating‐heart CABG with M‐CPB is a safe procedure and it provides an optimal operative exposure with significantly more complete coronary revascularization when compared to OPCAB. Beating‐heart CABG with the support of a M‐CPB is the operation of choice when total coronary revascularization is needed.     

Total arterial off-pump versus on-pump coronary revascularization: comparison of early outcome

BACKGROUND AND AIM: To assess differences in the early outcome after complete arterial myocardial revascularization with (ONCAB) or without cardiopulmonary bypass (OPCAB). METHODS: Out of 870 consecutive CABG procedures 58 OPCAB and 91 ONCAB patients receiving exclusive arterial grafts were analyzed. OPCAB patients had more single-vessel (p < 0.0001), less triple-vessel (p < 0.0001) or left main disease (p = 0.0021), higher angina class (p = 0.003), unstable angina (p < 0.0001) or previous PTCAs (p < 0.0001). RESULTS: ONCAB was associated with longer operations (182.5 +/- 38 vs. 147 +/- 56 min; p = 0.0001) and more anastomoses/patient (3.2 +/- 1 vs. 2 +/- 0.9; p < 0.0001), but incomplete revascularization was similar in both groups (11% vs. 17%; p = ns). ITA use was identical, whereas single left internal thoracic artery (LITA) use (25.9% vs.1%; p < 0.0001) and LITA jump anastomoses (10.3% vs. 7.7%; p < 0.0001) were more frequent in OPCAB. Radial artery (RA) use (89% vs. 46.6%; p < 0.0001) and RA jump anastomoses (57.1% vs. 12.1%; p < 0.0001) were more frequent in ONCAB. Mortality, arrhythmias, cerebro-vascular accidents (CVA), and renal failure were similar, but ventilatory support shorter (8.8 +/- 11.8 vs. 15.6 +/- 9.4 h; p < 0.0001) and cardiac enzyme release smaller (p < 0.0001) after OPCAB with a trend toward less myocardial infarction (1.7% vs. 7.7%; p = 0.12) and low output (1.7% vs. 8.8%; p = 0.089), and more respiratory complications (10.3% vs. 2.2%; p = 0.056). CONCLUSIONS: Arterial OPCAB patients have less extensive CAD, but more severe symptoms. Early outcome is similar concerning mortality, arrhythmias, CVA, renal failure, or ICU and hospital stay, but with shorter ventilatory support and lower cardiac enzymes with a trend toward lower myocardial infarction and low output, but higher respiratory complication rates after OPCAB.     

Cardiotomy Suction: A Major Source of Brain Lipid Emboli During Cardiopulmonary Bypass

Background. Brain injury remains a significant problem in patients undergoing cardiac surgery assisted by cardiopulmonary bypass (CPB). Autopsy brain specimens of patients after cardiac operations with CPB reveal numerous acellular lipid deposits (10 to 70 μm) in the microvasculature. We hypothesize that these small capillary and arterial dilatations result from a diffuse inflammatory response to CPB or from emboli delivered by the bypass circuit. This study was undertaken to determine which aspect of CPB is most clearly associated with these dilatations.

Methods. Thirteen dogs were studied in four groups: group I (n = 3), right-heart CPB; group II (n = 2), lower-extremity CPB; group III (n = 3), hypothermic CPB; and group IV (n = 5), hypothermic CPB with cardiotomy suction. All dogs in all groups were maintained on CPB for 60 minutes and then euthanized. Brain specimens were harvested, fixed in ethanol, embedded in celloidin, and stained with the alkaline phosphate histochemical technique so that dilatations could be counted.

Results. All dogs completed the protocol. The mean density of dilatations per square centimeter for each group was as follows: group I, 1.77 ± 0.77; group II, 4.17 ± 1.65; group III, 4.54 ± 1.69; and group IV, 46.5 ± 14.5. In group IV (cardiotomy suction), dilatation density was significantly higher than in group III (hypothermic cardiopulmonary bypass) (p = 0.04) and all other groups (p = 0.04).

Conclusions. Blood aspirated from the surgical field and subsequently reinfused into dogs undergoing CPB produces a greater density of small capillary and arterial dilatations than CPB without cardiotomy suction, presumably because of lipid microembolization.     

Off pump versus conventional on pump coronary artery bypass: a review

Despite many years of clinical and experimental research, the contribution of Cardiopulmonary Bypass (CPB) and cardioplegic arrest to morbidity and mortality following cardiac surgery remains unclear. In the last few years, Off-Pump Coronary Artery Bypass grafting (OPCAB) has gained widespread attention as an alternative technique to conventional On-Pump Coronary Artery Bypass grafting (ONCAB). It has provided an opportunity to compare the operations, in similar patient groups, with or without CPB and cardioplegic arrest. Although initial studies performed on low risk patients preferably with single vessel disease showed favorable outcome, we currently lack larger properly randomized high quality studies which show definite benefit. Proponents of off-pump surgery state that the avoidance of the CPB leads to significantly reduced myocardial ischemia-reperfusion injury, post-operative systemic inflammatory response, postoperative pulmonary complications, hospital stay and cost, a feature that may improve the clinical and economical outcomes. However, perfection in surgical technique, completeness of revascularization and whether the off pump method leads to improved outcome are still burning issues. In this review, OPCAB is found to be significantly better than the ONCAB in reducing cost, hospital stay, blood transfusion requirements, incidence of post-operative pulmonary complications, systemic inflammation and post-operative atrial fibrillations in most of the studies. The comparison show almost equivocal results regarding mortality, survival, quality of life, re-intervention rate, risk of stroke, cognitive decline and GI complication.     

β2 Adrenoceptor gene therapy ameliorates left ventricular dysfunction following cardiac surgery

Objective: Heart surgery is associated with impairment of the myocardial β-adrenoceptor (βAR) system. Effective therapies for post-operative ventricular dysfunction are limited. Prolonged inotrope exposure is associated with further βAR down-regulation. Left ventricular (LV) dysfunction and myocardial βAR impairment were assessed following cardiopulmonary bypass (CPB) and cardioplegic arrest in a pig model. Transfer of the human β₂-adrenoceptor transgene (Adeno-β₂AR) during cardioplegic arrest was then tested as a potential therapy. Methods: Five groups of six neonatal piglets were studied. One group did not undergo surgery (Group A). Adeno-β₂AR or phosphate buffered saline (PBS) were delivered via the aortic root during cardioplegic arrest. Groups B (PBS) and C (Adeno-β₂AR) were assessed at 2 days while Groups D (PBS) and E (Adeno-β₂AR) were assessed at 2 weeks from the time of surgery. An LV micromanometer was inserted under sedation to obtain pressure recordings following surgery. βAR density was measured subsequently. Results: Following cardiac surgery LV βAR density was reduced (104±5.7 vs 135±6.1 fmol/mg membrane protein; P=0.007), and, in response to β agonist stimulation, LV dP/dt_max was reduced (4337±405 vs 5328±194 mmHg/s; P<0.05) compared to animals which did not undergo surgery. Adeno-β₂AR therapy during cardiac surgery resulted in elevated LV βAR density (520±250.9 fmol/mg) 2 days post-operatively compared to PBS (104±5.7 fmol/mg; P=0.002) and compared to the no surgery group (135±6.1 fmol/mg; P=0.002). Elevated LV βAR density was also present at 2 weeks (315±74.1 vs 119±7.1 fmol/mg; P=0.002). In addition, Adeno-β₂AR therapy enhanced β agonist stimulated LV dP/dt_max (5348±121 vs 4337±405 mmHg/s; P<0.05) and heart rate (209±6.9 vs 173±11.0 bpm; P<0.05), and reduced LVEDP (2.1±0.4 vs 6.4±1.8 mmHg; P<0.05) compared to PBS treatment. Interestingly, gene delivery was cardiac-selective and beneficial effects on function persisted for 2 weeks. Moreover, β₂AR gene transfer ameliorated LV dysfunction following surgery such that there were no significant differences between non-operated controls and animals treated with Adeno-β₂AR during CPB and cardioplegic arrest. Conclusions: Reduced βAR density and impaired LV function were present following CPB and cardioplegic arrest. Cardiac-selective β₂AR gene transfer during CPB resulted in amelioration of LV dysfunction after cardiac surgery. Such a technique may offer a new approach to post-operative ventricular support.