Real-time patency control with thermal coronary angiography in 1401 coronary artery bypass grafting patients

Localization of coronary bypass targets in hard-to-see coronary arteries

BACKGROUND

Precise identification of coronary arteries and selection of anastomotic sites are critical stages of coronary bypass surgery. Visualization of coronary arteries is occasionally challenging when the heart is covered with a thick layer of fat or scar tissue. In this paper, we review the methods to localize the coronary arteries during coronary surgery.

METHODS

Prior publications were searched to summarize all available methods for localization of coronary arteries during coronary surgery.

RESULTS

Five clinically recognized and three experimental techniques from the literature review are reviewed and summarized.

CONCLUSIONS

Knowledge of various techniques of coronary artery identification in hard-to-see coronary arteries is an important asset in coronary surgery and especially useful during the most critical option of the most common heart surgery.

Impact of Bypass Flow Assessment on Long-Term Outcomes in Patients with Chronic Limb-Threatening Ischemia

BACKGROUND

Transit time flow meter (TTFM) allows quick and accurate intraoperative graft assessment. The main study goal is to evaluate the influence of graft flow measurements on long-term clinical outcomes in patients with chronic limb-threatening ischemia (CLTI) undergoing bellow the knee (BTK) vein bypass surgery.

METHODS

Between January 1st, 1999 and January 1st, 2006, 976 CLTI consecutive patients underwent lower extremity bypass surgery. When applying the exclusion criteria, 249 patients were included in the final analysis. Control measurements were performed at the end of the procedure. Patients were divided according to the mean (more/less than 100 ml/min) and diastolic graft flow (more/less than 40 ml/min) values in four groups. The primary endpoints were a major adverse limb event (male) and primary graft patency.

RESULTS

After the median follow-up of 68 months, a group with the mean graft flow below 100 ml/min and the diastolic graft flow below 40 ml/min had the highest rates of male (χ² = 36.60, DF = 1, P < 0.01, log-rank test) and the worst primary graft patency (χ² = 53.05, DF = 1, P < 0.01, log-rank test).

CONCLUSION

In patients with CLTI undergoing BTK vein bypass surgery, TTFM parameters, especially combined impact of mean graft flow less than 100 ml/min and diastolic graft flow less than 40 ml/min, were associated with an increased risk of poor long-term male and primary graft patency.

Transesophageal Echocardiographic Estimation of Coronary Sinus Blood Flow for Predicting Favorable Postoperative Transit Time Coronary Graft Flow Measurements: A Pilot Study

BACKGROUND

Augmentation of coronary artery flow by surgical grafting increases coronary sinus blood flow (CSBF), which can be quantified on transesophageal echocardiography (TEE). However, transit time flowmetry (TTF) technology remains the most used intraoperative technique for coronary artery graft assessment. The purpose of the present pilot study was to evaluate the predictive value of TEE-based CSBF estimation for identifying favorable TTF graft measurements.

DESIGN

Prospective observational study.

SETTING

Single university hospital.

PATIENTS

Forty patients undergoing triple vessel coronary artery bypass grafting.

MEASUREMENTS AND MAIN RESULTS

CSBF was assessed on TEE examination before and after revascularization, estimating the percentage increase in CSBF (∆CSBF). Postoperative TTF graft measurements were averaged to compute mean diastolic filling (DF) and pulsatility index (PI). Subjects were grouped based on favorable (PI ≤ 3, DF ≥ 50%) and unfavorable (PI > 3, DF < 50%) parameters. The group with PI ≤ 3 (n = 32) had significantly higher ∆CSBF compared with the group with PI > 3 (n = 8) (38.22% ± 12.05%, 13.75% ± 3.37%, p < 0.001). ∆CSBF was higher in the DF ≥ 50% group (n = 35) (36.40 ± 12.99) in contrast to DF < 50% group (n = 5) (11.80 ± 2.59%). A strong negative and significantly positive correlation was observed between ∆CSBF with PI, DF (r = -0.903, 0.571, respectively, p < 0.001). A ∆CSBF ≥15.5% was found to predict a mean PI ≤ 3 and DF ≥ 50% with sensitivity and specificity of 100% and 62.5% for PI and 100% and 100% for DF. A ∆CSBF ≥19% demonstrated a sensitivity and specificity of 100% and 100%, 100% and 91.4% for prediction of PI ≤ 3 and DF ≥ 50%, respectively.

CONCLUSION

TEE-based demonstration of an augmented CSBF can ensure favorable TTF graft parameters, guiding the adequacy of surgical revascularization.

Intraoperative transit-time flow measurement in on-pump coronary artery bypass graft surgery: Single center experience

Background

This study aims to evaluate the effects of graft dysfunction detected by intraoperative transit-time flow measurement on the outcomes of on-pump coronary artery bypass graft surgery.

Methods

A total of 1,240 patients (856 males, 384 females; mean age 57.4±12.1 years; range, 47 to 74 years), who underwent isolated on-pump coronary artery bypass graft surgery via median sternotomy performed by the same surgical team, were reviewed retrospectively. With the introduction of transit-time flow measurement into practice at our clinic in 2006, all patients regularly underwent transit-time flow measurement during surgery in order to evaluate the graft patency. Interpretation of the data obtained using the transit-time flow measurement in patients who underwent surgery has directed our decision as to whether to perform graft revision. Patients were evaluated for early- and late-period mortality/ morbidity, perioperative and postoperative myocardial infarction, and intraaortic balloon requirement.

Results

A total of 3,596 grafts in the perioperative period was evaluated using transit-time flow measurement. Anastomosis/graft revision, new anastomosis/patch plasty to distal native artery or free left internal mammary artery graft was performed in 146 grafts of 143 patients in whom transittime flow measurement showed insufficient patency. Four of six patients who developed peri/postoperative myocardial infarction were found to have perioperative hypotension, ST elevation, and wall motion abnormality on transesophageal echocardiography before closure of the sternum. The flow was corrected by extending the short length of the grafts with insufficient flow after transit-time flow measurement and it was recorded that transit-time flow measurements were at normal values at these four grafts. Two patients developed acute myocardial infarction in the postoperative period and stent was applied in one vessel of each patient; however, one of these patients died. Sixteen patients were inserted intraaortic balloon pump, four of which being in the preoperative period. Revision surgery was performed due to bleeding in 56 patients and sternal infection in 12 patients. Of all patients, 28 (2.3%) died in the early postoperative period.

Conclusion

We believe that transit-time flow measurement may be an important tool in evaluating graft function and contribute to eliminate the causes of graft failure during surgery.

Thermal camera as a pain monitor

Objectives

Today, many subjective methods are used to measure pain. Wong Baker and Hicks Facial Pain Scale is one of the most commonly used method. Clinicians grade pain according to the facial mimetic reaction of the patient. Unfortunately, there is no objective measure for monitoring pain. By using the same principle of the Wong Baker and Hicks Facial Pain Scale, in this study, we aimed to objectively measure pain by using a thermal camera to detect instant facial temperature changes.

Materials and methods

Thirty volunteers who attended blood collection unit were subjected to facial thermal monitoring and measurements were obtained 5 minutes before needle puncture (BNP), during needle puncture (DNP), and after needle puncture (ANP). Data were processed with TestoIRSoft 3.8 software program and mean temperatures of the whole face (FFM) and highest temperature points (HP), horizontal line (HOR) between two pupils and first glabellar wrinkle, and bilateral lines starting from the nasolabial sulcus to oral commissure (NLS-1 at right, NLS-2 at left) were evaluated. All data were statistically analyzed with paired sample t-test.

Results

Statistically, temperature measurements of HOR, NLS-1, NLS-2, HP, and FFM were significantly higher between BNP and DNP, significantly lower between ANP and DNP, and significantly higher between BNP and ANP (p<0.05). The most interesting result in our analysis was that the HP point was between the two eyebrows in 26 of the 30 volunteers.

Conclusion

Our results suggest that a thermal camera can be used to objectively monitor pain and in follow-up. However, further studies involving non-healthy volunteers (especially high-fever patients, children, immunosuppressive patients, and cancer and intensive care patients) should be performed.

The use of thermography in early detection of tissue perfusion disorders in rats

Introduction

Tissue perfusion disorders can be present in various diseases and progress in the form of arterial ischemia or venous stasis with accompanying local changes in temperature.

Aim

To use of thermography in the diagnostics of early periods of tissue perfusion disorders before the clinical symptoms occur.

Material and methods

Thirty-two male rats were used. After anesthesia the skin on lower limbs was shaved and femoral vessels of both sides were exposed. In 10 rats the left femoral artery was ligated, in 12 rats the left femoral vein was ligated and in the 10 remaining rats both left femoral vessels were ligated. Thermography of the limbs was performed before the vessels were ligated and after a period of 24 h. The pictures were taken every 5 s during 3 min. Before the measurement, the tissues were cooled down for 20 s with a 5°C water compress. The rate of temperature return to the limbs was evaluated.

Results

Statistically significant differences were observed after the 24-hour period on the thigh after the ligation of the vein, and on the shank and the foot after ligation of the artery. After the ligature of both vessels, statistically significant differences occurred immediately after their ligature within the thigh and shank and after 24 h on the foot.

Conclusions

The results show that cameras with an accuracy of 0.05°C can be used to detect tissue perfusion disorders. The special diagnostic value is the ability to detect perfusion disorders before clinical symptoms occur.

Real-time graft flow assessment using epigraftic ultrasonography during coronary artery bypass grafting

OBJECTIVES

Real-time graft flow assessment in the operative field has been performed to ascertain the patency in coronary artery bypass grafting (CABG). This study aims to evaluate the efficacy of graft flow assessment by epigraftic ultrasonography.

METHODS

CABG was performed in 135 patients from January 2010 to December 2012. One hundred and ten patients (81.4%) underwent both real-time graft flow measurement using epigraftic ultrasonography and coronary angiography (CAG) with a total of 249 grafts. Parameters were obtained from flow velocity curves in all grafts. The grafts were divided into two groups: patent grafts (Group A) and failing grafts (Group B). All parameters were compared in these two groups. Logistic regression analysis was performed to detect the predictors of graft failure and receiver operating characteristic (ROC) curve analysis was used to calculate the optimal cut-off value of the predictors of graft failure.

RESULTS

The overall patency as measured by CAG of the grafts was 97.2% (242/249). Logistic regression analysis revealed that the percentage of systolic and diastolic reverse flow (%sRF, %dRF) as well as the pulsatility index (PI) were predictors of early postoperative graft failure. ROC curve analysis revealed that mean velocity <12.5 cm/s, %sRF >9.3%, %dRF >4.1% and PI >4.4 were predictors of early graft failure.

CONCLUSIONS

In this series, epigraftic ultrasonography depicted graft flow clearly. Epigraftic ultrasonography is a useful tool to predict graft failure during CABG. This technique is easily performed using a conventional linear ultrasound transducer.

Cineangiographic intraoperative evaluation of venous grafts during coronary bypass surgery

BACKGROUND AND OBJECTIVE

Evaluation of graft patency is an important component of coronary bypass surgery. In the present study, intraoperative cineangiography was performed in a cardiovascular hybrid operating room to evaluate anastomosis quality and patency of coronary venous grafts.

METHOD

This prospective study evaluated coronary bypass grafts in 34 patients between January 2012 and June 2012. Radiopaque material was administered into the grafts through a vessel cannula before the proximal anastomosis. Then, cineangiographic images were obtained using a mobile C-arm cineangiography system. The myocardial perfusion scintigraphy (MPS) of the patients was compared between preoperative and first month postoperative periods to assess graft function.

RESULTS

The localization of the grafts in the target vessel, structural status of the grafts, anastomosis line, and availability of the target vessel were easily evaluated. Angiographic defects were detected in two grafts (3%, n = 60) in two patients (6%, n = 34). Staining was observed in the distal myocardial segments of the saphenous vein grafts following the administration of radiopaque material. The procedure took eight minutes, on average (range, 5-14 minutes), and a mean of 15 mL (range, 10-35 mL) of opaque material was used. None of the patients developed intraoperative myocardial infarction, postoperative complications, or contrast material-induced renal failure. No mortality was observed. The distal myocardial segments of saphenous vein grafts were detected to be perfused 92% normally, 5% reversibly defective, and 3% irreversibly defective with postoperative MPS controls.

CONCLUSION

Cineangiographic graft evaluation in a hybrid operating room is a practical, safe, noninvasive, easily available, and easily applicable method.

Enhanced surgical imaging: laparoscopic vessel identification and assessment of tissue oxygenation

BACKGROUND

Inherent to minimally invasive procedures are loss of tactile feedback and loss of three-dimensional assessment. Tasks such as vessel identification and dissection are not trivial for the inexperienced laparoscopic surgeon. Advanced surgical imaging, such as 3-charge-coupled device (3-CCD) image enhancement, can be used to assist with these more challenging tasks and, in addition, offers a method to noninvasively monitor tissue oxygenation during operations.

STUDY DESIGN

In this study, 3-CCD image enhancement is used for identification of vessels in 25 laparoscopic donor and partial nephrectomy patients. The algorithm is then applied to two laparoscopic nephrectomy patients involving multiple renal arteries. We also use the 3-CCD camera to qualitatively monitor renal parenchymal oxygenation during 10 laparoscopic donor nephrectomies (LDNs).

RESULTS

The mean region of interest (ROI) intensity values obtained for the renal artery and vein (68.40 +/- 8.44 and 45.96 +/- 8.65, respectively) are used to calculate a threshold intensity value (59.00) that allows for objective vessel differentiation. In addition, we examined the renal parenchyma during LDNs. Mean ROI intensity values were calculated for the renal parenchyma at two distinct time points: before vessel stapling (nonischemic) and just before extraction from the abdomen (ischemic). The nonischemic mean ROI intensity values are statistically different from the ischemic mean ROI intensity values (p < 0.05), even with short ischemia times.

CONCLUSIONS

We have developed a technique, 3-CCD image enhancement, for identification of vasculature and monitoring of parenchymal oxygenation. This technique requires no additional laparoscopic operating room equipment and has real-time video capability.

Evaluation of real-time infrared intraoperative cholangiography in a porcine model

BACKGROUND

Intraoperative cholangiograms (IOCs) may increase cost, surgical time, and radiation exposure of staff and patients. The authors introduce the application of passive infrared imaging to intraoperative cholangiography as a feasible alternative to traditional fluoroscopic IOCs.

METHODS

A porcine model was used in which the gallbladder, cystic duct, common bile duct (CBD), and duodenum were exposed and an 18-gauge angiocatheter was inserted into the cystic duct. Infrared emission was detected using a digital infrared camera positioned 30 to 60 cm above the abdomen. Infrared images were taken in real time (approximately 1/s) during infusion of room-temperature saline. A thermoplastic polymer stone then was inserted into the CBD. Once the artificial stone was placed, room-temperature saline was again injected. A standard single-shot renograffin IOC was obtained to confirm the obstruction. The experiment was concluded by creation of a lateral 2-mm CBD injury immediately proximal to the duodenum followed by infusion of room-temperature saline.

RESULTS

Six pigs were used in this study. Baseline infrared imaging was able to capture a visible temperature decrease, outlining the lumen of the CBD. With injection of room-temperature saline, a decrease in temperature was visualized as a dark area representing flow from the CBD to the duodenum. After placement of the synthetic stone, real-time infrared images displayed slowing of the injected bolus by the obstruction. The obstruction was correlated with fluoroscopic IOCs. Finally, after partial transection of the CBD, the infrared camera visualized saline flowing from the site of injury out into the peritoneal cavity.

CONCLUSIONS

The CBD anatomy, obstruction, and injury can be clearly visualized with an infrared camera. Intraoperative infrared imaging is an emerging method already being used in several surgical fields. Ultimately, the integration of infrared and laparoscopic technology will be necessary to make infrared technology important in laparoscopic cholecystectomy.

Thermal coronary angiography in pediatric coronary artery bypass grafting

A 2-year-old boy was referred to our institution for treatment of coronary artery obstruction after an arterial switch operation (ASO). We performed a pediatric coronary artery bypass graft (CABG) with skeletonized left internal thoracic artery (LITA). The patient was 88 cm tall and weighed 11 kg. The left anterior descending (LAD) coronary artery was also identified about 1 mm in diameter. Anastomotic failure of imposed stricture was detected with an infrared camera (IRIS-V, VERITAS, Tokyo, Japan). In the situation of CABG, thermal coronary angiography (TCA) is very useful to reveal satisfactory blood flow into the left coronary system during this procedure.

The impact of intraoperative transit time flow measurement on the results of on-pump coronary surgery

OBJECTIVE

The purpose of this study is to evaluate the effect of detection of graft dysfunction by intraoperative transit time flow measurement (TTFM) on the surgical results of on-pump coronary artery bypass grafting.

METHODS

Two hundred patients undergoing on-pump isolate coronary artery bypass grafting via median sternotomy performed by the same surgical team were included into the study. TTFM was routinely performed for assessment of graft patency during operation after a transit time flow meter became available in our center in February 2006. The last 100 consecutive patients before this date formed the control group (Group A), and the first 100 consecutive patients after this date formed the study group (Group B). Interpretation of the values obtained using the TTFM in Group B patients has allowed us to reach a decision whether or not to revise a graft. Preoperative and postoperative variables of the two groups were compared.

RESULTS

The clinical features of control and study groups were comparable. We assessed patency of 303 grafts using TTFM. Revision was required for nine grafts in nine patients based on unsatisfactory TTFM findings. Incidences of overall mortality (p<0.05), peri- or postoperative myocardial infarction (p<0.05) and intraaortic balloon pump insertion (p<0.05) were significantly lower in Group B than Group A.

CONCLUSIONS

We believe that TTFM seems to be a crucial tool for deciding if a graft is well-functioning or not, and it allows for improvement of graft failure during operation. Our results suggest that detection of graft dysfunction intraoperatively by TTFM improves the surgical outcome.

A Stereo Thermographic System for Intra-operative Surgery

A stereo far-infrared (FIR) system based on the trigonometric parallax is presented in this paper for locating the distal arterial tree from the coronary artery bypass graft. The system can obtain the wide angle-of-view range information in the near distance by changing the optical path of one fixed uncooled FIR camera. Meanwhile, the speed of pixel movement on the FIR imaging plane is discussed for avoiding the problem on the imaging blur because the images are taken in sequence from a scanning mirror for the real-time monitor of the operation. Besides, the view range is also considered under the different system parameter conditions. After the structure parameters are simulated for evaluating the performance, the optimum system can be designed. This thermal imaging technique is inexpensive, noninvasive and feasible for intra-operative surgery.

Modeling of temperature mapping for quantitative dynamic infrared coronary angiography for intraoperative graft patency control

OBJECTIVES

Intraoperative application of thermal coronary angiography based on dynamic infrared imaging leads to useful qualitative information concerning coronary artery bypass graft flow and anatomy. Additional quantitative flow estimation is desirable to detect graft failures. The aim of this study was to develop a heat-transfer model for quantitative flow estimation in an experimental setup. The first clinical results in coronary artery bypass grafting are reported.

METHODS

Dynamic infrared imaging was applied in pig hearts to collect video data of the rewarming process of the left anterior descending artery supplied by antegrade perfusion. For mathematic description, we used the dynamic enthalpy balance for open systems, and a Laplace transformation was carried out. Therefore the time constant tau was calculated by performing a nonlinear fit procedure on the averaged dynamic temperature curves recorded over a left anterior descending artery segment. Subsequently, left internal thoracic artery-left anterior descending artery bypass graft flow was assessed intraoperatively. Effective left anterior descending artery flow was determined by using a transit-time flowmeter.

RESULTS

Tau is a system constant and changes depending on the flow and the system capacity. Assuming system capacity to be constant, tau only depends on the flow. It follows from the differential equation that there is a potential relation between tau and the flow. An excellent comparison (R2 = 0.968, P <.005) was demonstrated. By using the algorithms, quantitative flow estimation in pig hearts was possible. For clinical application, the formulas were applied to intraoperatively derived dynamic temperature curves with a good comparison to the actual left internal thoracic artery-left anterior descending artery flow.

CONCLUSION

The developed heat-transfer model allows for precise measurement of graft flow by using dynamic infrared imaging and can be applied for noninvasive graft flow estimation in beating-heart surgery.