Off-pump CABG with synchronized arterial flow ensuring system

A novel coronary active perfusion system using a conventional intra-aortic balloon pump for off-pump coronary artery bypass grafting

OBJECTIVE

It is important for coronary active perfusion systems to avoid myocardial ischemia during off-pump coronary artery bypass grafting. We have developed a new concept for a perfusion system to pump blood based on changes in helium gas volume. This system uses a conventional intra-aortic balloon pump to activate the perfusion pump. Our study used basic and animal experiments to investigate the most suitable system for coronary perfusion using this new concept.

METHODS

A conventional intra-aortic balloon pump was used to supply power. A device for perfusion was developed with a balloon placed inside a stiff syringe barrel. The device was connected to the helium gas line of the intra-aortic balloon pump. Changes in flow with changes in augmentation level were noted when volumes outside and within the balloon were changed. Six pigs with occlusion of the left anterior descending artery were used for system validation, with monitoring to identify changes in hemodynamics and cardiac enzyme levels.

RESULTS

In the basic experiment, an 80-mL outside volume and 3.0-mL inner volume resulted in the greatest percentage change in flow rate with respect to changes in augmentation. In the animal experiment, the new coronary active perfusion system prevented myocardial ischemia during coronary occlusion.

CONCLUSIONS

We clarified the most suitable method for our new coronary active perfusion system. Using this system, safe anastomosis was consistently performed in animal experiments. Clinically, off-pump coronary artery bypass may potentially be performed more safely and easily using this new system.

Robot-assisted minimally invasive direct coronary artery bypass grafting. ThoraCAB

BACKGROUND

 The aim of this study was to assess the outcome of robot-assisted minimally invasive direct coronary artery bypass grafting (MIDCAB), which is also termed "ThoraCAB".

METHODS AND RESULTS

 From 2005 to 2013, 35 consecutive patients underwent MIDCAB via a small thoracotomy on a beating heart. Before performing MIDCAB, the internal thoracic arteries (ITAs) were endoscopically harvested through 3 ports using the da Vinci Surgical System in a completely skeletonized fashion. Distal anastomosis was hand-sewn using a vacuum stabilizer, and a coronary artery active perfusion system was used to prevent myocardial ischemia during anastomosis. Successful robot-assisted ITA harvesting was achieved in all patients. There was an average of 1.7±0.8 grafts (range, 1-3 grafts) per patient. No patient needed mechanical ventilation for more than 24h. There were no deaths, strokes or myocardial infarctions, and none of the patients required conversion to median sternotomy.

CONCLUSIONS

 Robot-assisted ITA harvesting is safe and feasible. ThoraCAB is a relatively simple procedure and allows multivessel bypass grafting after a small thoracotomy. Therefore, it is expected that ThoraCAB will become the standard procedure for minimally invasive coronary revascularization and will be used in totally endoscopic CABG in the future. 

Clinical validation of coronary artery flow through an intracoronary shunt during off-pump coronary artery bypass grafting

OBJECTIVES

Intracoronary shunts have been developed for a bloodless field and preserved forward flow preventing ischemia during off-pump coronary artery bypass (OPCAB) surgery. However, reports directly measuring the forward flow through the shunt in clinical settings are lacking.

METHODS

Using a 7.5-MHz Doppler probe, we investigated the coronary flow through a 1.5-mm shunt inserted into the left anterior descending artery (LAD) for anastomosis with the internal thoracic artery during OPCAB in 30 consecutive patients. The following Doppler flow parameters were obtained before and after shunting: peak velocity, mean velocity, time-velocity integral, and flow.

RESULTS

No patients developed significant electrocardiographic changes and the peak value of postoperative myocardial band of creatine kinase was 17 ± 16 IU/L. All Doppler flow parameters of the LAD decreased significantly after shunting; peal velocity: 71.3 ± 34.6 cm/second to 54.5 ± 25.3 cm/second (-24% ± 27%), mean velocity: 33.3 ± 18.3 cm/second to 26.3 ± 14.0 cm/second (-21% ± 23%), and time-velocity integral: 28.7 ± 12.1 cm to 19.0 ± 7.1 cm (-28% ± 14%), and flow: 38.7 ± 16.8 mL/minute to 25.0 ± 9.5 mL/minute (-31% ± 13%) (P < .01).

CONCLUSIONS

The LAD flow is preserved at least 50% through a 1.5-mm intracoronary shunt, although the flow pattern was attenuated, during OPCAB anastomosis. The Doppler evaluation of the coronary artery flow before and after shunting is useful to justify the protective use of the shunt on myocardial perfusion during OPCAB.

Multivessel awake off-pump coronary bypass grafting using median approach: technical considerations

OBJECTIVE

: Several reports of awake off-pump coronary artery bypass grafting (AOCAB) under high thoracic epidural anesthesia (TEA) for single-vessel grafts have been published, but few have described its application in multiple bypass procedures. We report the procedures and safety of AOCAB for multivessel disease.

METHODS

: Fifty-five multivessel AOCAB (52 men, 3 women; aged 68 ± 9.5 years) were performed at our hospital between 2003 and 2010. A medium sternotomy was made after TEA was established. During coronary artery anastomosis, a stabilizer and an apical suction device were used, and a coronary artery active perfusion system was used to maintain flow distal to the anastomosis. Pneumothorax due to pleural opening, when occurred, was repaired using Neoveil sheet and drainage tube.

RESULTS

: There was no operative death and no cerebral ischemia, cardiac arrhythmia, and chronic obstructive pulmonary disease. Operating time was 177 ± 35 minutes. Left internal thoracic artery was used in 55 anastomoses, right internal thoracic artery in 7, gastroepiploic artery in 17, radial artery in 48, and saphenous vein in 24. Time of anastomosis was 4.93 ± 0.92 minutes for left anterior descending coronary artery, 4.75 ± 1.21 minutes for circumflex artery, and 4.98 ± 1.02 minutes for right coronary artery. Intraprocedural pneumothorax occurred in 17 cases; 14 were repaired and nonintubated AOCAB was accomplished, 1 was intubated, and 2 had temporary assisted ventilation and laryngeal mask. Time to discharge was 15.5 ± 8.4 days.

CONCLUSIONS

: Multivessel AOCAB under TEA is not only feasible but also safe. Multiple grafts can be harvested under TEA, and complete vascularization is possible under constant monitoring of blood pressure and consciousness.

Beating-heart totally endoscopic coronary artery bypass grafting: report of a case

This case report presents beating-heart totally endoscopic coronary artery bypass grafting (TECAB) for single-vessel coronary artery disease. A 72-year-old man with isolated left anterior descending (LAD) coronary artery disease was considered eligible for TECAB. Left internal thoracic artery (LITA) mobilization and subsequent off-pump revascularization applying the LITA to the LAD in a closed chest environment was performed using the da Vinci surgical system (Intuitive Surgical, Mountain View, CA, USA). The LITA was first harvested completely in a totally skeletonized fashion through three incisions 1-2 cm long in the left thoracic wall. The LAD was immobilized with the aid of a heart stabilizer. The LITA was then anastomosed to the LAD with 10 interrupted sutures of a Nitinol self-closing S15 U-clip device (Medtronic, Minneapolis, MN, USA) on the beating heart without the use of cardiopulmonary bypass. The time acquired to perform anastomosis was 20 min, and the total operative time was 5 h 34 min. The postoperative course was uneventful and the patient was discharged 5 days after the operation. Beating-heart TECAB was successfully performed for this patient with single-vessel LAD disease. This approach may be an evolutionary step toward beating-heart multivessel TECAB.

Comparison of active and passive coronary perfusion in off-pump coronary artery bypass grafting

The myocardial protective effects of active and passive coronary perfusion were compared during off-pump coronary artery bypass grafting (OPCAB) in coronary stenosis model. An internal shunt tube was placed in the proximal left anterior descending arteries of adult dogs to produce a 75% coronary stenosis model. In 10 animals passive coronary perfusion was performed using an internal shunt tube placed in a pseudo-anastomotic site, and active coronary perfusion was performed through an external shunt tube. Ischemia was examined at normal and low blood pressure, based on hemodynamics, regional myocardial blood flow, and oxygen and lactate extraction in the perfused area. With passive perfusion, regional myocardial blood flow decreased and oxygen extraction and regional lactate production increased at normal blood pressure, indicating myocardial ischemia. Regional myocardial blood flow further decreased at low blood pressure. In contrast, regional myocardial blood flow with active perfusion did not change at normal or low blood pressure, and oxygen and lactate extraction were unchanged, indicating prevention of myocardial ischemia. Myocardial ischemia can occur with passive perfusion even at normal blood pressure. Active coronary perfusion that provides sufficient regional perfusion prevents myocardial ischemia during coronary artery anastomosis in OPCAB.

A coronary active perfusion system for off-pump coronary artery bypass grafting in an experimental porcine model: the relationship between flow rate and myocardial function

We developed a coronary active perfusion system (synchronized arterial flow ensuring system [SAFE-System]) to prevent myocardial ischemia during distal anastomosis in off-pump coronary artery bypass grafting (CABG). The purpose of this study was to identify the relationship between the flow rate of the SAFE-System and myocardial function. Studies were performed on pigs, which were divided into five groups: external shunt perfusion group (group A, n = 6); 0.1 mL/beat flow rate for the SAFE-System group (group B, n = 6); 0.2 mL/beat flow rate group (group C, n = 6); 0.3 mL/beat flow rate group (group D, n = 6); and 0.4 mL/beat flow rate group (group E, n = 6). Regional myocardial blood flow and left ventricular function were monitored for 30 min. The regional myocardial blood flow in group A was severely decreased (P < 0.001), and was significantly lower than in the other groups (P < 0.001). The slope of the end-systolic pressure-volume relationship, and the slope of the preload recruitable stroke work relationship in groups A, D, and E were lower than in groups B and C. As compared with the use of a passive external shunt, a coronary active perfusion system provides adequate myocardial blood flow and hemodynamics. It was possible to maintain left ventricular function when using 0.1 or 0.2 mL/beat flow rate. The use of a coronary active perfusion system appears to make the off-pump CABG procedure safer and may increase the application of off-pump bypass grafting.

Controversies in the Use of Intraluminal Shunts During Off-Pump Coronary Artery Bypass Grafting Surgery

Technical advances have made the performance of multivessel off-pump coronary artery bypass feasible. Snaring and intraluminal shunts are the techniques used for vascular control. Snaring provides a bloodless surgical field, is usually well tolerated by the patient, and is supported by years of clinical experience. Intraluminal shunts aim to achieve hemostasis at the arteriotomy site and to allow antegrade flow to provide myocardial protection. There are unresolved issues regarding whether shunts have a clinical benefit, do provide adequate flow to provide myocardial protection, and whether they cause significant endothelial damage. In this article, we have reviewed the literature to lend perspective to these issues.