Instant myocardial blood flow monitor: its calibration and assessment of flow capacity of the intracoronary shunt tube

Total Endoscopic Beating-Heart Coronary Artery Bypass Grafting Using A New 3D Imaging System

OBJECTIVE

: Since 1999, the authors of this study have performed total endoscopic beating-heart coronary artery bypass. They have developed a new three-dimensional (3D) endoscopic imaging system and have used it successfully in three patients.

METHODS

: From January 2004, a new 3D endoscopic imaging system was used. This device, composed of an optical high-resolution, 3D endoscope and two liquid crystal monitors, gives bright, natural, 3D imaging and enables quick, precise manipulation. After the 15-mm port for the 3D endoscope was inserted through fourth intercostal space (ICS) in the posterior axillary line, the left internal thoracic artery (LITA) was taken down endoscopically in semiskeletonized fashion, using two instrumental 5-mm ports (third and sixth anterior axillary ICS). The pericardium was then opened, and the left anterior descending artery was identified. Another 10-mm port for an endoscopic needle holder was inserted through fourth ICS in the midclavicular line. Three ports were placed in the fourth ICS in line for the anastomosis. An original suction stabilizer was inserted through the first instrumental port, and the left anterior descending artery was immobilized. A conventional end-to-side anastomosis was done with 8-0 Prolene running sutures.

RESULTS

: The average LITA harvesting time was significantly shortened from 68 minutes with two-dimensional imaging to 36 minutes with new 3D imaging. The average anastomotic time was shortened from 34 minutes with two-dimensional imaging and 27 minutes with former 3D imaging to 17 minutes with new 3D imaging. There were no complications and no operative deaths.

CONCLUSIONS

: This new 3D endoscopic imaging system facilitates quick, precise anastomosis and is a useful device for endoscopic coronary bypass surgery.

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.

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.

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.

Hybrid surgical angiogenesis: omentopexy can enhance myocardial angiogenesis induced by cell therapy

BACKGROUND

The conditions at the injection site are important in cell transplantation for severe ischemic heart disease. The omentum is both a well-vascularized tissue and a source of angiogenic factors. We examined the effectiveness of autologous bone marrow-derived mononuclear cells (BM-MNCs) with or without omentopexy in a large animal model.

METHODS

Myocardial infarction was generated in the lateral wall by ligation of coronary artery branches in miniswine. Animals received BM-MNC injection with or without omentopexy. Controls received saline only. Three weeks after surgery, regional myocardial blood flow and contractility were measured, and density of arterioles was evaluated immunohistologically. Angiography and postmortem examinations were performed to determine collateral communication.

RESULTS

Regional myocardial contractility was significantly improved by BM-MNC transplantation both with and without omentopexy (0.29 +/- 0.02 vs 0.11 +/- 0.03, p < 0.01, 0.30 +/- 0.02 vs 0.12 +/- 0.01, p < 0.01, respectively). Relative regional myocardial blood flow in the combined omentopexy group was significantly higher than the controls both at rest (1.05 +/- 0.11 vs 0.57 +/- 0.07, p < 0.01) and under stress (1.09 +/- 0.08 vs 0.40 +/- 0.10, p < 0.01). The number of arterioles (< 50 microm) in both groups were higher than the controls (88.1 +/- 5.00 vs 38.1 +/- 8.99, p < 0.01 and 109.2 +/- 9.91 vs 38.1 +/- 8.99, p < 0.01, respectively). The number of large arterioles (> 50 microm) in the combined omentopexy group was significantly higher than in both BM-MNC alone (26.9 +/- 2.4 vs 17.6 +/- 1.8, p = 0.011) and controls (26.9 +/- 2.4 vs 10.0 +/- 1.3, p < 0.01). Collateral communication between the omentum and myocardium was demonstrated by angiography and postmortem injection.

CONCLUSIONS

The BM-MNC transplantation may attenuate cardiac contractile dysfunction, and omentopexy may enhance angiogenesis induced by BM-MNC transplantation.