Ultrasonic Transit Time Flowmetry in Robotic Totally Endoscopic CABG.

Successful use of transit time flowmetry in robotic totally endoscopic coronary bypass operation is reported to demonstrate its applicability and ease of use in evaluating the function of grafts in such operations.

INTRODUCTION

Robotic totally endoscopic coronary bypass operation (TECAB) was introduced by Loulmet et al. in 1999.[1] It is a promising minimally invasive approach suitable for selected patients who require myocardial revascularization. The clinical feasibility and safety of this approach had been demonstrated in few retrospective studies.[1-4] The only graft used in the majority of such operations is the left internal thoracic artery (LITA) to the left anterior descending (LAD). Few published reports described two- or three-vessel endoscopic bypass, or hybrid (TECAB and PCI) procedures.[34]

One of the difficulties in this operation is being unable to evaluate the function of the bypass graft. Due to lack of tactile sensation in used instruments, even simple palpation of the graft is not possible in endoscopic procedures. Intra-operative angiography is very difficult except in modern hybrid cathlab/operation rooms. The function of the graft can only be tested post-operatively by ECG, cardiac markers, coronary CT scan, or angiography.

Intra-operative ultrasonic transit time flowmetry proved to be a reliable and reproducible technique in evaluating flow in CABG operations for more than 10 years.[5] We report a beating heart TECAB operation in which we used this technique to evaluate LITA to LAD graft function successfully.

CASE PRESENTATION

The patient, a 61-year-old man, was admitted on October 15th, 2010, for elective TECAB operation. He had coronary artery disease with angina and a history of NSTEMI. Risk factors included hypertension and hyperlipidemia. Echocardiography showed anteropical hypokinesia with EF 48%. Coronary angiography showed single-vessel CAD with 90% lesion in the proximal LAD which was not suitable for stenting. Operative risk Euroscore was 2.

The operation was performed using Da Vinci robotic surgical system. Totally endoscopic operation was performed. The LITA was dissected as a pedicle graft, and anstomosed end-to-side to LAD using beating heart technique with endoscopic octopus stabilizer, intra-coronary shunt, and continuous 7/0 GoreTex suture. The flow in the graft was measured by ultrasonic transit time flowmetry using handless 2 mm probe (MediStim VeriQ, Norway) [Figure 1]. The flow was 19 ml/min, pulsatility index (PI) 1.9, and diastolic flow (DF) 71% [Figure 2]. These good figures indicated excellent functionality of the graft. The measurements added less than 5 mins to the operative time, and gave a good sense of security and satisfaction about the procedure.

Figure 1

Ultrasonic transit time handless flow meter probe size 2 mm placed around the LIMA-LAD pedicle graft and held by robotic forceps

Figure 2

The flowmetry screen showing good flow wave pattern in the graft with flow of 19 ml/min, PI=1.9, and DF=71%

Post-operatively, the patient had bleeding from a small LITA branch which required re-exploration via a small thoracotomy incision to control the bleeding. Otherwise, the postoperative course was smooth and the patient was discharged on the third post-operative day.

DISCUSSION

Robotic TECAB is a promising approach for myocardial revascularization. It is progressing rapidly with the improved instruments and the added fourth arm to the Da Vinci robotic system through which endoscopic suction cardiac stabilizer and irrigation system can be introduced. The potential of advancing the application of this minimally invasive operation to multiple coronary arteries has been well demonstrated lately by Srivastava et al.[4] The use of intra-operative transit time flowmetry had been reported in 1 patient in 2006,[6] 5 patients in 2009,[3] and 129 patients in 2010.[4] The availability of hybrid cathlab/operating room facilities will make it possible to expand the use of this minimally invasive TECAB operation in combination with pre-, intra-, or post-operative coronary stenting to be applied in multiple-vessel myocardial revascularization.

Ultrasonic transit time flowmetry, as demonstrated, is a simple technique that can help in the intra-operative evaluation of grafts. Short- and long-term results of such a hybrid approach need confirmation with prospective randomized studies.