Current state of surgical myocardial revascularization

Esophagectomy combined with off-pump coronary artery bypass grafting through left posterolateral incision is safe and feasible for esophageal cancer associated with coronary artery disease

Controversy still exists as to whether surgical treatment has any impact on the long-term survival of esophageal cancer (EC) patients with coronary artery disease treated with curative esophagectomy combined with off-pump coronary artery bypass grafting (OPCABG). Therefore, the aim of this study was to introduce and assess the effect of esophagectomy combined with OPCABG on both short- and long-term outcomes. From January 2010 to January 2015, 1428 EC or esophagogastric junction cancer patients underwent surgical treatment at Henan Chest Hospital, Zhengzhou, China. The clinical data of 25 patients who underwent EC resection through a left thoracotomy following OPCABG and the perioperative characteristics and follow-up results were analyzed. The majority of the patients were male, and the EC stage was predominantly cT2N0-1M0 II. The most common pathological types were squamous cell carcinoma. The EC surgeries consisted of 15 chest anastomosis procedures and 10 cervical anastomosis procedures with aortocoronary graft implantation (mean: 2.36 grafts per patient). The mean total operative time was 330.8 ± 83.5 minutes. The median intensive care unit and hospital lengths of stay were 1.72 and 21.16 days, respectively. Resection without macroscopic residual disease (R0) was achieved in all of the patients. The most frequent complications included pulmonary infections (24%), arrhythmias (24%), pleural effusion (12%), and esophageal anastomotic leakage (8%). There were no postoperative deaths or myocardial infarctions within 30 days after the surgery. The overall 1-, 3-, and 5-year survival rates were 88%, 40%, and 24%, respectively, with a median survival time of 43 months. In the short-term, radical resection of EC following OPCABG is a safe and feasible treatment with low postoperative mortality rates. In the long-term, simultaneous surgery is acceptable and is associated with favorable overall and disease-free survival.

Effects of Remote Ischemic Preconditioning in Patients Undergoing Off-Pump Coronary Artery Bypass Graft Surgery

Purpose

This study aimed to evaluate effects of remote ischemic preconditioning (RIPC) on myocardial injury in patients undergoing off-pump coronary artery bypass graft surgery (OPCABG).

Methods

Sixty-five patients scheduled for the OPCABG were randomly assigned to control (n = 32) or RIPC group (n = 33). All patients received general anesthesia. Before the surgical incision, RIPC was induced on an upper limb with repeated 5-min ischemia and 5-min reperfusion for four times. Blood samples were collected from right internal jugular vein. Plasma levels of IL-6, IL-8, IL-10, TNF-α, cTnT, HFABP, IMA, and MDA were detected at pre-operatively and 0, 6, 18, 24, 48, 72, and 120 h after the surgery. Left internal mammary artery (LIMA) and great saphenous vein (GSV) was cut into 2–3 mm for Western blot analysis of Hif-1α.

Results

In the present study, RIPC treatment significantly reduced plasma levels of cardiac troponin T (p < 0.05), heart-type fatty acid binding protein (p < 0.05), ischemia modified albumin (p < 0.05), malondialdehyde (p < 0.05), as well as plasma levels of pro-inflammatory cytokines including IL-6, IL-8, and TNF-α (P < 0.05, respectively). RIPC treatment significantly increased hypoxia-inducible factor-1α (p < 0.05) expression as well. Mechanical ventilation time for postoperative patients was shortened in RIPC group than those in control group (17.4 ± 3.8 h vs. 19.7 ± 2.9 h, respectively, p < 0.05).

Conclusion

RIPC by upper limb ischemia shortens mechanical ventilation time in patients undergoing OPCABG. RIPC treatment reduces postoperative myocardial enzyme expression and pro-inflammatory cytokine production. RIPC is a protective therapeutic approach in the coronary artery bypass graft surgery.

Hemodynamic Changes During Heart Displacement in Aorta No-Touch Off-Pump Coronary Artery Bypass Surgery: A Pilot Study

OBJECTIVE

To evaluate the sequential changes of hemodynamic and metabolic parameters in patients who underwent aorta no-touch off-pump coronary artery bypass surgery (OPCAB).

METHODS

Prospective study involving twenty-seven consecutive patients who underwent aorta no-touch OPCAB. The FloTrac/PreSep/Vigileo™ system (Edwards Lifesciences) was used to continuously record heart rate (HR), mean arterial blood pressure (MABP), central venous pressure (CVP), continuous cardiac index (FCI), stroke volume (SV), stroke volume variation (SVV), and central venous oxygen saturation (ScvO2). The parameters were assessed 5 min before, during and 5 min after each anastomosis (left anterior descending [LAD], posterior descending [PD], obtuse marginal [OM] and diagonal [Dg]). Postoperative lactate was also evaluated.

RESULTS

There was no significant change in HR and MABP for all anastomoses, except for MABP during PD grafting (-10.1±2.7 mmHg, P=0.03). There was a significant decrease in ScvO2 only during PD and OM anastomoses (-9.4±0.4, P=0.03; -4.4±0.4, P=0.02; respectively). CVP drop after PD manipulation was strongly associated with a higher lactate during the first hours after surgery (r=-0.82; P=0.001). These hemodynamic changes were transient and entirely recovered after the heart was returned to its anatomical position. No significant differences were observed in FCI, SVV, or the systemic vascular resistance index (SVRI) during all anastomoses, except for a drop in SVRI during PD grafting (-8.03±2.3, P=0.007). SV tended to decrease during the procedure in all territories, but with statistically significant drop only in PD and OM grafting (-10.4±1.2, P=0.02; -13.6±5.1, P=0.007; respectively).

CONCLUSION

Heart displacement for performing aorta no-touch OPCAB is well tolerated, with transient and endurable hemodynamic variations.

Minimally invasive coronary artery bypass grafting

Minimally invasive cardiac surgery (MICS)-CABG is a technique that at its core has patient comfort, early return to routine activities, meeting patient expectations for less invasive options, and maintaining the highest possible standards of care and outcomes. The technique requires not only surgical dexterity but also integration of significant technological advancements in patient care. At a time when percutaneous interventions are often prescribed on the pretext of increased patient comfort and demand, minimally invasive myocardial revascularization becomes even more relevant. Minimally invasive myocardial revascularization is ever evolving and encompasses both small-incision open techniques as well as endoscopic-assisted procedures. The success of the procedure depends not only on the learning curve and familiarity with the technology but also on appropriate patient selection. Mere feasibility of the technique is not sufficient, and the results have to be comparable with the long-established techniques of conventional coronary artery bypass grafting both in terms of early morbidity and mortality as well as long-term outcomes. In this review, we discuss patient selection and technical aspects of minimally invasive coronary artery bypass grafting. We also provide an evidence-based comparison to early and long-term outcomes with conventional coronary artery bypass grafting. Finally, we review the uptake and outcomes of minimally invasive revascularization in the Indian subcontinent.

A review of hybrid coronary revascularization

Purpose

Hybrid coronary revascularization is an emerging treatment strategy for coronary artery disease. We will review the reasons for the development of this strategy, describe surgical techniques, and review outcomes. Finally, we will discuss the future of hybrid revascularization and explain why it will grow as a treatment modality.

Methods

For this review, we conducted an unstructured review of the literature for articles related to hybrid coronary revascularization, bypass surgery, and percutaneous coronary interventions.

Results

Hybrid coronary revascularization has been shown in large series to have excellent results. These include fast recovery time, low mortality and rates of complications, and excellent surgical graft patency. There may be increased need for revascularization over conventional bypass surgery.

Conclusions

The combination improved surgical techniques including a robotic surgery platform, as well as the ever-improving efficacy and durability of coronary stents have made hybrid coronary revascularization an attractive option for many patients. It offers a minimally invasive approach to surgery while avoiding the poor patency of saphenous vein grafts. In appropriately selected patients, this may be an ideal treatment strategy that minimizes risks and maximizes short- and long-term benefits.

Inhibitory Effect of TLR4 Gene Silencing on Intimal Hyperplasia of Vein Grafting

PURPOSE

The present study aimed to explore the regulating effect of Toll-like receptor 4 (TLR4) on intimal hyperplasia in rat vein grafts.

METHODS

Rat models of external jugular vein carotid artery bypass grafting were established. Afterward, TLR4 small interfering RNA (siRNA) recombinant plasmids were constructed, which were transfected into rat vein graft bypass to study the effect of TLR4 silencing on intimal hyperplasia and to explore the underlying mechanisms. Real-time polymerase chain reaction and Western blot were used to detect the expression levels of TLR4 and inflammatory factors in TLR4 siRNA-transfected vein graft bypass. The intimal thickness was evaluated using hematoxylin-eosin staining.

RESULTS

Compared with the scramble siRNA group, the intimal thickness of vein grafting was decreased significantly, while the inflammatory factors including interleukin (IL) 1β, IL-6, and tumor necrosis factor α in grafted vein were dramatically downregulated in the TLR4 siRNA group.

CONCLUSION

These results showed that local silencing of TLR4 in the vein grafts could inhibit intimal hyperplasia by downregulating the expression of inflammatory factors in the vein grafts, suggesting that TLR4 can be used as a new target for therapy of vascular intimal hyperplasia.

Reviewing hybrid coronary revascularization: challenges, controversies and opportunities

Two main approaches to myocardial revascularization currently exist, coronary artery bypass and percutaneous coronary intervention. In patients with advanced coronary artery disease, coronary artery bypass surgery is associated with improved long term outcomes while percutaneous coronary intervention is associated with lower periprocedural complications. A new approach has emerged in the last decade that attempts to reap the benefits of bypass surgery and stenting while minimizing the shortcomings of each approach. This new approach, hybrid coronary revascularization, has shown encouraging early results. Minimally invasive techniques for bypass surgery have played a large part of bringing this approach into contemporary practice.

Anesthetic issues for robotic cardiac surgery

As innovative technology continues to be developed and is implemented into the realm of cardiac surgery, surgical teams, cardiothoracic anesthesiologists, and health centers are constantly looking for methods to improve patient outcomes and satisfaction. One of the more recent developments in cardiac surgical practice is minimally invasive robotic surgery. Its use has been documented in numerous publications, and its use has proliferated significantly over the past 15 years. The anesthesiology team must continue to develop and perfect special techniques to manage these patients perioperatively including lung isolation techniques and transesophageal echocardiography (TEE). This review article of recent scientific data and personal experience serves to explain some of the challenges, which the anesthetic team must manage, including patient and procedural factors, complications from one-lung ventilation (OLV) including hypoxia and hypercapnia, capnothorax, percutaneous cannulation for cardiopulmonary bypass, TEE guidance, as well as methods of intraoperative monitoring and analgesia. As existing minimally invasive techniques are perfected, and newer innovations are demonstrated, it is imperative that the cardiothoracic anesthesiologist must improve and maintain skills to guide these patients safely through the robotic procedure.

New technologies in coronary artery surgery

Coronary artery disease remains the leading cause of death in developed countries. Major recent studies such as SYNTAX and FREEDOM have confirmed that coronary artery bypass grafting (CABG) remains the gold standard treatment in terms of survival and freedom from myocardial infarction and the need for repeat revascularization. The current review explores the use of new technologies and future directions in coronary artery surgery, through 1) stressing the importance of multiple arterial conduits and especially the use of bilateral mammary artery; 2) discussing the advantages and disadvantages of off-pump coronary artery bypass; 3) presenting additional techniques, e.g. minimally invasive direct coronary artery bypass grafting, hybrid, and robotic-assisted CABG; and, finally, 4) debating a novel external stenting technique for saphenous vein grafts.

Risk of renal dysfunction after less invasive multivessel coronary artery bypass grafting

OBJECTIVE

Several centers have established that off-pump, multivessel coronary artery bypass grafting performed via a small thoracotomy (MVST) is feasible. However, this procedure can be challenging when posterolateral coronary targets need to be grafted. We hypothesized that use of cardiopulmonary bypass via peripheral access (MVST-PA) would improve outcomes compared with a completely off-pump approach (OP-MVST).

METHODS

This was a prospective observational study of patients undergoing OP-MVST (n = 46) versus MVST-PA (n = 45) using bilateral internal mammary artery grafts onto the left anterior descending coronary artery and circumflex/right coronary artery distribution. Hemostasis was quantified by measuring platelet function (aggregometry), chest tube output, thrombolysis in myocardial infarction bleeding score (%hematocrit change at 24 hours), and transfusion requirements. The rate of mortality and major morbidity at 30 days was defined according to The Society of Thoracic Surgeons criteria. Estimated glomerular filtration rate (normalized to baseline levels) was determined daily until discharge.

RESULTS

The OP-MVST versus MVST-PA groups had similar risk factors at baseline and risks of composite morbidity/mortality at 30 days. However, renal failure was significantly increased after OP-MVST (10.87 vs 0%, P = 0.05), and MVST-PA affected hemostasis as evidenced by inhibition of platelet function (latency to response on aggregometry, 29.9 vs 17.9 seconds; P = 0.04) and higher transfusion requirement (2.31 vs 0.85 units of red blood cells/patient, P = 0.04; 55.6% vs 34.8% transfused; P = 0.059). However, 24-hour chest tube output was similar (645 vs 750 mL; P = 0.53).

CONCLUSIONS

In comparison with a completely off-pump strategy, use of cardiopulmonary bypass to assist MVST reduced the risk of renal dysfunction with only modest tradeoffs in other morbidities, for example, altered coagulation and higher transfusion requirements. These data justify further study of the effect of MVST-PA on renal complications.

Effects of remote ischemic preconditioning with postconditioning in patients undergoing off-pump coronary artery bypass surgery--randomized controlled trial

BACKGROUND

Myocardial injury is associated with an adverse outcome after off-pump coronary artery bypass graft surgery (OPCAB). The authors conducted a randomized controlled trial to evaluate whether remote ischemic preconditioning (RIPC) with remote ischemic postconditioning (RIPostC) reduces myocardial injury in patients undergoing OPCAB.

METHODS AND RESULTS

Seventy patients scheduled for OPCAB were randomly assigned to an RIPC+RIPostC group (n=35) or a control group (n=35). In the RIPC+RIPostC group, 4 cycles of 5-min ischemia and 5-min reperfusion were done on a lower limb before anastomoses (RIPC) and after anastomoses (RIPostC). RIPC+RIPostC significantly reduced postoperative serum troponin I levels (P=0.001). The area under the curve for postoperative troponin I was 48.7% lower in the RIPC+RIPostC group (median [interquartile range], 21.3 h·ng⁻¹·ml⁻¹, 16.5-53.1 h·ng⁻¹·ml⁻¹ vs. 41.5 h·ng⁻¹·ml⁻¹, 24.6-90.2 h·ng⁻¹·ml⁻¹, P=0.020). There was no significant difference in creatinine levels and PaO₂/F(i)O₂ ratios between the 2 groups.

CONCLUSIONS

RIPC+RIPostC by lower limb ischemia decreased postoperative myocardial enzyme elevation by almost half postoperatively in patients undergoing OPCAB.

Effect of tranexamic acid on transfusion requirement in dual antiplatelet-treated anemic patients undergoing off-pump coronary artery bypass graft surgery

BACKGROUND

Anemia is not rare in patients presenting for coronary artery bypass graft surgery (CABG) and as these patients are frequently on dual antiplatelet therapy (DAPT), the coexisting conditions could potentially increase the risk of bleeding and transfusion. The aim of this study was to evaluate the effect of tranexamic acid (TA) on blood loss and transfusion in preoperatively anemic patients who continued DAPT until within 5 days of off-pump CABG (OPCAB).

METHODS AND RESULTS

Seventy-six anemic patients were randomized into 2 groups: TA group receiving TA (1g bolus followed by infusion at 200mg/h) and a Control group receiving the same volume of saline. The amount of blood loss and transfusion requirement during, and at 4 and 24h after the operation were assessed. Patients' characteristics and operative data were similar between the groups. During the perioperative period, which combined the intraoperative and postoperative 24h data, the TA group received significantly smaller amounts of packed red blood cells and fresh frozen plasma. Total amount of perioperative blood loss was similar between the groups, although the blood loss during the postoperative 4h was significantly less in the TA group.

CONCLUSIONS

TA infusion could reduce the amount of transfusion during the perioperative period in patients with preoperative anemia who continue DAPT until within 5 days of OPCAB.

The golden age of minimally invasive cardiothoracic surgery: current and future perspectives

Over the past decade, minimally invasive cardiothoracic surgery (MICS) has grown in popularity. This growth has been driven, in part, by a desire to translate many of the observed benefits of minimal access surgery, such as decreased pain and reduced surgical trauma, to the cardiac surgical arena. Initial enthusiasm for MICS was tempered by concerns over reduced surgical exposure in highly complex operations and the potential for prolonged operative times and patient safety. With innovations in perfusion techniques, refinement of transthoracic echocardiography and the development of specialized surgical instruments and robotic technology, cardiac surgery was provided with the necessary tools to progress to less invasive approaches. However, much of the early literature on MICS focused on technical reports or small case series. The safety and feasibility of MICS have been demonstrated, yet questions remain regarding the relative efficacy of MICS over traditional sternotomy approaches. Recently, there has been a growth in the body of published literature on MICS long-term outcomes, with most reports suggesting that major cardiac operations that have traditionally been performed through a median sternotomy can be performed through a variety of minimally invasive approaches with equivalent safety and durability. In this article, we examine the technological advancements that have made MICS possible and provide an update on the major areas of cardiac surgery where MICS has demonstrated the most growth, with consideration of current and future directions.

Human internal thoracic artery grafts exhibit severe morphological and functional damage and spasmic vasomotion due to oxidative stress

Background

The internal thoracic artery (ITA) is the first choice for myocardial revascularization, but atherosclerotic lesions and perioperative vasospasm may still limit its functionality. Oxidative stress via the peroxynitrite – poly-(ADP-ribose) polymerase (PARP) cascade plays an important role in the pathogenesis of impaired vascular tone via endothelial injury. We aimed to investigate and describe the histology, PARP activation and functionality of ITA grafts and to assess the possible beneficial effect of PARP-inhibition.

Material/Methods

ITA specimens from 47 patients (26 men, mean age 66.2±1.7 years) who underwent coronary bypass surgery were processed for histological and immunohistochemical studies for oxidative stress and PARP activation, and were functionally tested with acetylcholine (ACh) and sodium nitroprusside (SNP) with or without PARP inhibition.

Results

The sections showed atherosclerotic alterations and oxidative and nitrosative stress were evidenced by positive 3-nitrotyrosine, 4-hydroxynonenal and PAR stainings. Functionally, 88.1% reacted to K-Krebs, 68.7% exhibited contraction after 1 μM phenylephrine, 29.9% exhibited relaxation to 30 μM Ach, and all precontracted segments relaxed to 30 μM SNP. High amplitude vasomotion was observed in 47.8% of the segments, which could be abolished by the application of 10 μM SNP. Incubation of the preparations with PJ34 did not improve endothelium-dependent vasodilation.

Conclusions

ITA grafts are severely damaged both morphologically and functionally in patients undergoing coronary artery bypass surgery, but PARP inhibition cannot improve their functional characteristics. The topical use of SNP to the ITA during the operation may improve vascular functions by dilating the vessels and eliminating the eventual spasmic vasomotion.