Internal Thoracic Artery Flow Research Articles

Modeling and simulation of smart magnetic self-assembled nanomicelle trajectories in an internal thoracic artery flow for breast cancer therapy.

Magnetic drug targeting (MDT) is one of the most modern techniques in cancer therapy for its ability to reduce the side effects of chemotherapy experienced by systemic drug administration. In this study, a comprehensive mathematical model has been developed to predict the drug particle trajectories of anticancer dasatinib magnetic nanomicelles (DAS-MNM) released in an internal thoracic artery (ITA) blood flow for breast cancer therapy using an external magnetic field. Several factors are investigated in regard to the efficiency of MDT through the ITA, including magnetic field strength (MFS), relative magnetic permeability, magnet size, drug particle size, and initial position of drug particle. The drug particle trajectory results confirmed the successful MDT using an external magnetic field with a capture efficiency of more than 90%. This was achieved by employing a wide range of particle sizes of DAS-MNM close to the external magnetic field source at the arterial wall than in other positions. Moreover, the results showed that the number of trapped particles increased with increasing both MFS and drug particle diameter within the target tissue, while the drug particle permeability did not have a considerable effect on the particle retention. In addition, for achieving a successful drug/cargo delivery through the arteries, the magnetic field, the particle size, and the initial release locations should be adjusted simultaneously. The present work offers insights into the critical factors in MDT with a significant impact on breast cancer therapy, tissue engineering, and regenerative medicine. Magnetic drug targeting model of anticancer dasatinib magnetic nanomicelles (DAS-MNM) released in an internal thoracic artery blood flow for breast cancer therapy.

Occurrence rate and fate of competitive flow of the left internal thoracic artery used in Y-composite grafts

ObjectivesWe evaluated the occurrence rate of competitive flow and the fate of grafts of left internal thoracic artery (LITA)-to-left anterior descending coronary artery (LAD) anastomosis after coronary artery bypass grafting with Y-composite grafts using early and 1-year angiography. MethodsFrom 2008 to 2017, 923 patients underwent off-pump coronary artery bypass grafting using Y-composite grafting based on the in situ LITA. Early postoperative angiography was performed for all patients. One-year angiography (mean, 13.2 ± 3.1 months) was performed for 86.7% (800 of 923) of patients. ResultsThe early occlusion rate of LITA with Y-composite graft (CompLITA) to LAD was 0.7%. Among 917 patent CompLITA-LAD grafts, competitive flow was observed in 39 patients (4.3%). Multivariable analysis showed that the degree of LAD stenosis (odds ratio, 0.897; 95% CI, 0.875-0.920; P < .001) and 3-vessel disease (odds ratio, 5.632; 95% CI, 1.168-27.155; P = .031) were factors associated with the occurrence of competitive flow of CompLITA-LAD grafts. The receiver operating characteristics curve determined that the cutoff degree of LAD stenosis was 82.5% (sensitivity 82.1% and specificity 85.2%). The failure rate of CompLITA-LAD grafts seen on 1-year angiography was 58.3% in patients with competitive flow. Among patients with competitive flow, left main coronary artery disease was a protective factor (odds ratio, 0.055; 95% CI, 0.009-0.337; P = .002) against graft failure of the CompLITA-LAD seen on 1-year angiography. ConclusionsIn CompLITA-LAD, the degree of LAD stenosis and combined 3-vessel disease were associated with the occurrence of competitive flow. CompLITA-LAD grafts with early competitive flow showed a high 1-year graft failure rate of 58%.

Investigation of the effects of diabetes mellitus on left internal thoracic artery flow patterns in patients scheduled to undergo coronary bypass graft surgery

Diabetes mellitus (DM) plays a key role in the formation and prognosis of cardiovascular diseases. In this study, we aimed to investigate the effects of DM and glycemic control on left internal thoracic artery (LITA) Doppler flow in patients scheduled to undergo coronary artery bypass graft (CABG) surgery. Patients who were hospitalized with a planned isolated CABG operation to our clinic between October 1, 2019 and March 1, 2020 were consecutively included in this prospective study. The patients were divided into three groups as those without DM (Group 1), those with DM and HbA1c values of below 7.5 (Group 2), and those with DM and HbA1c values of 7.5 and above (Group 3). The differences between the LITA Doppler flow patterns of the patients were analyzed. The mean ages of Group 1 (n =103), Group 2 (n =42), and Group 3 (n =47) were 59.8 ± 9.6 years, 60.5 ± 9.3 years, and 61.9 ± 8.1 years, respectively. The groups differed in terms of diameter, volume, Vmax, pulsality index (PI), and resistive index (RI) values, both when the groups were compared among themselves (P < .001, for all), and when they were compared between those with (Groups 2 and 3) and without DM (Group 1) (P < .001, for all). Volume (R=-0.627, P < .001) and Vmax (R=-.450, P < .001) were moderately negatively correlated, while PI (R=.523, P < .001) and RI (R=0.598, P < 0.001) were moderately positively correlated with HbA1c levels. In this study, we showed that increased HbA1c levels may be associated with significant functional and structural changes of LITA.

Steering the Drug Release of Smart Magnetic Self-Assembled Nano Micelles in an Internal Thoracic Artery Flow for Breast Cancer Therapy

Steering the Drug Release of Smart Magnetic Self-Assembled Nano Micelles in an Internal Thoracic Artery Flow for Breast Cancer Therapy

Comparison of the internal thoracic artery flow dissected by video endoscopy or conventional technique.

ABSTRACTPurpose:To compare the blood flow in the internal thoracic artery when dissected endoscopically in a conventional manner, in addition to develop a reliable experimental training model for the surgical team.Methods:Paired experimental study. Ten pigs were operated and had both internal thoracic arteries dissected, the right with a conventional technique and the left by video endoscopy. The main outcomes to be studied were flow, length, and time of dissection of each vessel.Results:Blood flow measurements were performed with mean heart rate of 100 ± 16 bpm and mean arterial pressure of 89.7 ± 13 mm Hg. The mean blood flow of endoscopic dissection of the internal thoracic artery was 170.2 ± 66.3 mL/min and by direct view was 180.8 ± 70.5 (p = 0.26). Thus, there was no statistically significant difference between the flows, showing no inferiority between the methods.Conclusions:The minimally invasive dissection of the internal thoracic artery was shown to be not inferior to the dissection by open technique in relation to the blood flow in the present experimental model. In addition, the model that we replicated was shown to be adequate for the development of the learning curve and improvement of the endoscopic abilities.

Ministernotomy aortic valve surgery in patients with prior patent mammary artery grafts after coronary artery bypass grafting.

Patients with patent internal thoracic artery (ITA) grafts after prior coronary artery bypass grafting surgery who require aortic valve replacement (AVR) pose unique technical challenges for safe and optimal myocardial protection. The purpose of this study is to review our short- and long-term outcomes with redo minimally invasive AVR in patients with patent in situ ITA grafts. From 2008 to 2016, 48 patients with at least 1 patent in situ mammary artery graft underwent minimally invasive AVR. Preoperative computed tomography was performed in all patients to evaluate the relationship of patent grafts to the sternum. Retrograde coronary sinus and pulmonary vent catheters were placed via the right internal jugular vein. The in situ ITA grafts were not clamped during AVR. Transverse aortotomy, taking care to avoid the grafts arising from the aorta, was performed to expose the aortic valve. The median age of the patients was 78 years [Quartile 1 (Q1)-Quartile 3 (Q3): 71-81]. Thirty-nine (81%) patients were men, and 46 (96%) patients had aortic stenosis. The median cardiopulmonary bypass and cross-clamp times were 124 (Q1-Q3: 108-164) and 92 (Q1-Q3: 83-116) min, respectively. Moderate hypothermia at 28-30°C was used in all patients. Most patients received cold blood cardioplegia with antegrade induction and continuous retrograde delivery. Four patients received only retrograde delivery due to some degree of aortic insufficiency. Thirty-day mortality was 4% (2 of 48 patients). There was no conversion to full sternotomy, and no reoperations were performed for postoperative bleeding or sternal wound infection. Excluding the 2 patients who died in the hospital, the median postoperative length of stay was 7 days (Q1-Q3: 5-8). Overall survival at 1, 5 and 10 years was 94%, 87% and 44%, respectively. Percutaneous retrograde cardioplegia combined with antegrade cardioplegia and moderate hypothermia, without interruption of ITA flow, is a safe and reliable strategy in patients with patent ITA grafts undergoing aortic valve replacement. This strategy combined with a minimally invasive approach may reduce surgical trauma, and is a safe and effective technique in these challenging patients.

Effect of Papaverine on the Flow of Left Internal Thoracic (Mammary) Artery for Coronary Artery Bypass Grafting

Effect of Papaverine on the Flow of Left Internal Thoracic (Mammary) Artery for Coronary Artery Bypass Grafting

The impact of ligation of proximal side branches on blood flow and functional status of the internal thoracic artery in coronary anastomosis.

The effect of proximal side branches on the patency of the internal thoracic artery (ITA) is controversial. We used echocardiography and Doppler to verify the effect of ligation of branches on the flow and coronary flow reserve (CFR) of the grafted ITA in patients after coronary artery bypass grafting (CABG). We prospectively investigated 53 patients with preserved left ventricular ejection fraction (LVEF >50%) who underwent CABG of the ITA. In Group I (25 patients), major branches were ligated during ITA anastomosis to the left anterior descending (LAD) coronary artery, whereas no ligation was performed in Group II (28 patients). Systolic flow (SF), diastolic flow (DF), and total flow (TF = SF + DF) were measured by Doppler echocardiography at the proximal level of the ITA preoperatively, at early postoperative stage, and 6months after surgery. Dobutamine stress echocardiography (DSE) was performed at 6months to determine CFR. The ITA flow was predominantly systolic before surgery and diastolic in the postoperative period. We found no differences between the groups in DF. On DSE, SF (19.5±9mL/min vs 32.7±19mL/min; P=.003) and TF (79±21mL/min vs 101±47mL/min; P=.037) were higher in Group II. There were no differences in CFR (1.9±0.46 vs 2.11±0.56; P=.143). In patients with preserved LVEF, ligation of major side branches during anastomosis to the LAD does not alter ITA flow or CFR.

Effect of electrocautery on endothelial integrity of the internal thoracic artery: ultrastructural analysis with transmission electron microscopy.

The internal thoracic artery (ITA) is typically harvested from the chest wall by means of conventional electrocautery. We investigated the effects of electrocautery on endothelial-cell and vessel-wall morphology at the ultrastructural level during ITA harvesting. Internal thoracic artery specimens from 20 patients who underwent elective coronary artery bypass grafting were investigated in 2 groups. The ITA grafts were sharply dissected with use of a scalpel and clips in the control group (n=10) and were harvested by means of electrocautery in the study group (n=10). Each sample was evaluated for intimal, elastic-tissue, muscular-layer, and adventitial changes. Free flow was measured intraoperatively. Light microscopic examinations were performed after hematoxylin-eosin and Masson's trichrome staining. Transmission electron microscopy was used to evaluate ultrastructural changes in the endothelial cells and vessel walls of each ITA. In the sharp-dissection group, the endothelial surfaces were lined with normal amounts of original endothelium, endothelial cells were distinctly attached to the basal lamina, cytoplasmic organelles were evident, and intercellular junctional complexes were intact. Conversely, in the electrocautery group, the morphologic integrity of endothelial cells was distorted, with some cell separations and splits, contracted cells, numerous large cytoplasmic vacuoles, and no visible cytoplasmic organelles. The subendothelial layer exhibited disintegration. Free ITA flow was higher in the sharp-dissection group (P=0.04). The integrity of endothelial cells can be better preserved when the ITA is mobilized by means of sharp dissection, rather than solely by electrocautery; we recommend a combined approach.

Comparison between the Doppler flowmetry and the free flow of dog's internal thoracic artery with and without use norepinephrine

This work aims to study comparatively the free flow and the Doppler flowmetry of the internal thoracic artery in anesthetized dogs, with and without continuous intravenous administration of norepinephrine. The sample was made up of ten mongrel dogs, which dissected the left and right internal thoracic arteries and evaluated your stream; first, by Doppler flowmetry and then by free flow. The mean arterial pressure and the diameter of the arteries at the beginning of the procedure were registered. The workflow checks by two methods occurred in three times: time zero, 10 and 25 minutes. After the first check in time zero, the continuous infusion of norepinephrine in the right atrium; other checks were made in the same way that the first time, to 10 and 25 minutes, in the same arteries and by two methods, each one in his artery, noting the results, as well as the corresponding average blood pressure. The results of the scan of the stream, between Doppler flowmetry and free flow, there were similar; being the first, zero times, ten and twenty-five minutes, respectively, 183, 230.1 and 237 ml/min compared to seconds, 168.6, 226.8 and 226.4 ml/min (P = 0.285). The mean arterial pressures of three times and the average diameter of the arteries, showed no statistically significant differences between the methods, so did not influence on the comparison of the results. The evaluations, both from Doppler flowmetry and free flow, were similar in three times checked.

Steal of Blood Flow from the Vertebral Artery to the Internal Thoracic Artery Anastomosed to the Coronary Artery

The left vertebral and internal thoracic arteries are branches of the left subclavian artery which, under physiological conditions, exhibit antegrade flow direction. On Doppler evaluation, the internal thoracic artery (ITA) flow shows a predominance of systolic component, but when anastomosed to the left coronary arteries, the prevalence of the diastolic component is usual. This predominance can become exacerbated and a situation that increases oxygen consumption by the myocardium can occur, such as what happens during dobutamine stress echocardiography, when the systolic component can be suppressed and the diastolic becomes the only component of the cardiac cycle. The two-dimensional and Doppler imaging allows anatomical assessment of arteries and the verification of normal and pathological flow patterns. Thus, the flow direction reversal of an artery can be compatible with steal of blood flow and an exacerbation of the diastolic component of the anastomosed internal thoracic artery (AITA) at Doppler may indicate good functional status of the vessel1-3. Occlusion of the left subclavian artery determines impairment of blood supply to the left arm, but the steal of blood flow from the left vertebral artery may improve limb perfusion. When the subclavian artery occlusion occurs in cases with ITA anastomosed to the left coronary arteries, the direction of the post-stenotic flow in symptomatic patients is variable and can be reverse in the vertebral and internal thoracic arteries4, have no reverse component5, be reverse only in ITA6 or, as in our patient, show preferential reverse flow from the left vertebral artery to the ITA.

Effect of topical vasodilator on internal thoracic artery blood flow. A placebo-controlled clinical study

Objective: The internal thoracic artery (ITA) is the conduit of choice for coronary artery bypass grafting (CABG). To avoid spasm of the ITA various topical vasodilators have been suggested either intraluminally or by topical application. In order to describe the best vasodilating agent for preparation of the ITA, a randomized double-blind placebo controlled clinical work was performed in a group of CABG patients. Methods: Three hundred consecutive patients submitted for elective first time coronary artery bypass grafting were randomly subdivided into five groups. The first measurement was performed shortly after the internal thoracic artery was dissected from the chest wall and the second just prior to performing distal anastomosis to the left anterior descending coronary artery. During the time interval between the two measurements topical vasodilator has been injected into the endothoracic fascia of the ITA using the following drugs: papaverine 2 mg/ml, nitrogly-cerin 1 mg/ml, nitroprusside 0.5 mg/ml, mixed solution include sodium nitroprusside (1 mg/ml) and diltiazem (0.5 mg/ml) and normal saline 0.9%. Results: No statistically significant differences were found between the groups in respect to age, body surface area, cardiopulmonary bypass time, cross clamping time, and time interval between the two flow measurements. Mean arterial pressure at the time of the first and second internal thoracic artery flow measurements did not show statistically significant differences either within or between the groups. In all five groups, the free flow of the internal thoracic artery increased significantly with time. However, no statistically significant differences were shown between the five groups with respect to second flow. Conclusions: We suggest that preparation of the ITA by topical vasodilators injection into the endothoracic fascia does not result in a significantly superior free flow than placebo.

Effects of Thoracic Epidural Anesthesia on Flow and Endothelium of Internal Thoracic Artery in Coronary Artery Bypass Graft Surgery

The internal thoracic artery (ITA) is the preferred conduit for coronary artery bypass graft (CABG) surgery. The authors investigated whether thoracic epidural anesthesia (TEA) as an adjunct to general anesthesia (GA) can increase the blood flow of the ITA. A prospective randomized study. A university hospital. Patients with ischemic heart disease. Thirty patients scheduled for elective CABG surgery were randomized to receive either GA (n = 15) or GA + TEA (n = 15) after receiving institutional review board approval. Demographics showed similarity between the groups. The epidural catheter was inserted in the thoracic region between T1 and T5 levels. In the GA + TEA group, the patients received a 20-mg bolus of 0.25% bupivacaine through epidural catheters 1 hour before surgery, and this was followed by the infusion (20 mg/h) of 0.25% bupivacaine. In all patients, ITA free blood flow was measured before cardiopulmonary bypass and without the administration of any vasodilatory agent. A short segment of ITA was excised for histologic examination; immunocytochemistry analysis was performed using antirabbit polyclonal VEGF antibody, rabbit polyclonal inducible nitric oxide synthase (i-NOS) antibody, and adenosine anti-A2B receptor antibody. The immunoreactivity rates then were evaluated. The mean ITA free flow in the GA + TEA group was significantly higher than in the GA group (56.0 ± 9.0 mL/min v 39.6 ± 14 mL/min, p = 0.001). Immunostaining intensity in the sections after incubation with each primary antibody increased in the GA + TEA group compared with the GA group. The results of this study indicated that TEA increased ITA free blood flow significantly via increased VEGF, i-NOS, and adenosine-A2B receptor expressions. Therefore, the use of TEA as an adjunct to GA might be considered as an alternative to vasoactive agents for increasing ITA flow in CABG surgery.

Different Flow Patterns Between Left and Right Internal Thoracic Artery Grafts Influence the Evaluation of Severe Graft Stenosis by Transthoracic Doppler Echocardiography

An increase in the diastolic to systolic flow velocity ratio (D/S) in the proximal left internal thoracic artery (ITA) after coronary artery bypass grafting (CABG) enables noninvasive assessment of graft patency by transthoracic Doppler echocardiography (TTDE). The increase in the D/S can be less pronounced at a site distant from the anastomosis. We postulated that proximal ITA flow patterns differ between the left and right ITAs and that the increase in D/S is less pronounced in the right than in the left proximal ITA. Proximal ITA flow was examined by TTDE in 129 consecutive patients after CABG of the left (75) or right (69) ITA to the left coronary artery. The mean D/S of the ITAs was compared with coronary angiography. The D/S was lower in the group with a patent right ITA than in the group with a patent left ITA (P < .05). The D/S of both the left and right ITAs negatively correlated with angiographic stenosis (r= 0.56 or 0.67, P < .001, respectively). The regression line was significantly shifted downward in the right ITA compared with the left ITA, according to analysis of covariance (P= .01). Graft stenosis was predicted by a D/S of <0.57 and <0.28 with an accuracy of 91% and 97% in the left and right ITAs, respectively. The patency of both left and right ITA grafts to the left coronary artery can be assessed using TTDE, but different cutoff values of D/S are required to diagnose severe ITA stenosis.

Decreasing sternum microcirculation after harvesting the internal thoracic artery

The effect of harvesting the internal thoracic artery (ITA) on blood supply to the sternum is not completely understood. Using a novel laser Doppler flow meter, we evaluated changes in sternum microcirculation prior to and after ITA harvesting. Forty-six patients (37 males, 69.4 ± 7.9 years) scheduled for coronary artery bypass grafting were enrolled into the study and divided into skeletonized (n = 23) and pedicled (n = 23) groups of patients with a left ITA. All right ITA were harvested using the skeletonized method. Sternal blood flow was measured presternally and retrosternally in the upper, middle, and lower sternal parts with a novel laser Doppler flow meter that measures blood flow at 1-mm depth using a 780-nm laser. Following median sternotomy, blood flow was measured before and after ITA harvesting. In all patients (46 left and 16 right ITA cases), the middle part of the retrosternal microcirculation deteriorated (middle: pre- 2.71 ± 1.49, post- 2.43 ± 1.01 ml min(-1)100 g(-1); p < 0.05), while blood flow of other parts did not change. In patients with left ITA divided into skeletonized and pedicled groups, although middle retrosternal blood flow decreased after harvesting in both groups, there was no difference in deterioration between the groups. In patients with right ITA, the middle and lower retrosternal blood flow also deteriorated. The degree of sternal microcirculation damage after ITA harvesting is not different between skeletonized and pedicled group patients, suggesting that skeletonization is not advantageous for maintaining sternal microcirculation.

Steal from Skeletonized Internal Thoracic Artery Graft during Hemodialysis after Coronary Artery Bypass Grafting

We used transthoracic Doppler echocardiography to evaluate the potential for flow variation in a skeletonized internal thoracic artery (ITA) graftc ipsilateral to an upper-extremity arteriovenous fistula during postoperative hemodialysis. Between October 2008 and May 2009, 7 patients in chronic hemodialysis underwent coronary artery bypass grafting. We selected 5 of these patients according to the following inclusion criteria: patients who were undergoing chronic hemodialysis via a left upper-extremity arteriovenous fistula and in whom the skeletonized left ITA was anastomosed to the left anterior descending artery as an in situ graft; the right ITA was not used as a graft; postoperative multidetector computed tomography evaluation of the coronary artery demonstrated patency of the left ITA. The following parameters were calculated at baseline, after the dialysis pump was on, before the pump was turned off, and after the pump was off: peak systolic velocity, end-diastolic velocity, time-averaged mean velocity, pulsatility index, and ITA diameter. Flow was calculated with the following formula: Flow = Time-Averaged Mean Velocity x (Half the Diameter of the ITA)2 x 60 x pi. When the hemodialysis pump was started, there was a significant reduction in the flow of the left ITA (P = .01), whereas there was no variation in the flow of the right ITA (P = .54). During dialysis, no patients experienced hypotension, arrhythmia, or angina. Just after the end of dialysis, the left ITA flow significantly increased (P = .01). Flow reduction of the ITA graft ipsilateral to an upper-extremity arteriovenous fistula develops during postoperative hemodialysis, even when the skeletonization technique is used.

Minimally invasive robotic coronary bypass on the beating heart using da Vinci S system

To summarize the experience of minimally invasive robotic coronary bypass on beating heart using da Vinci S in China. Fifty-six patients underwent selected robotic coronary bypass on beating heart from April 2007 to December 2008. All the patients had history of angina and the coronary arteriography showed severe stenosis in the left anterior descending artery (LAD), of which 10 cases had right coronary artery or left circumflex coronary (LCX) stenosis. The age was 33 to 74 years old, with a mean of (55.8 +/- 9.4) years old. The weight was (71.4 +/- 13.2) kg. All the patients had good lung function and had no medical history of pleurisy and thoracic surgery. CT scan of double internal thoracic artery (ITA) was routinely checked preoperatively. The procedures included: (1) The robotically assisted endoscopic atraumatic coronary artery bypass surgery. The approach was via a small left anterior thoracotomy (6 to 8 cm) after robotic ITA was taken down. The ITA was manually anastomosed to the LAD or LCX on beating heart. (2) Totally endoscopic coronary bypass graft on beating heart. After ITA harvesting, the endo stabilizer was inserted via the fourth port in the xiphoid area under endoscopic vision. The left ITA to the LAD grafting was done using U-clips on beating heart in a totally endoscopic manner using da Vinci S system through 4 ports. For all patients the ITA flow was checked by the Doppler flowmeter after anastomosis was completed. After the surgery was completed, the thoracic port was checked carefully to avoid bleeding. The operating procedures and a variety of clinical parameters were recorded and analyzed. (3) Stent placement after robotic surgery in a hybrid manner. The graft patency rate was evaluated by CT or arteriography. All patients successfully accepted robotic minimally invasive coronary bypass on the beating heart using da Vinci S surgical system without complications. The mean graft flow was (23.2 +/- 16.7) ml/min. And there was no surgical conversion and surgical death. Fifty-three patients received ITA to LAD grafts and 3 patients received double coronary artery bypass grafts as well. Ten cases received stent placement in separate session. The CT scan and angiography revealed patent grafts in all patients. There were no post-operative complications. All patients were discharged from hospital. As a new advanced approach of revascularization, robotic ITA harvesting and coronary anastomoses can be safely performed with the da Vinci S system. The procedure is minimally invasive and can offer enhanced ability to control precise and stable operative manipulations.

Milrinone Increases Flow in Coronary Artery Bypass Grafts After Cardiopulmonary Bypass: A Prospective, Randomized, Double-Blind, Placebo-Controlled Study

To compare the effects of a bolus of milrinone, 50 microg/kg, versus placebo on flow in coronary artery bypass grafts after cardiopulmonary bypass (CPB). A prospective, randomized, double-blind study. A university hospital. Forty-four patients with stable angina and left ventricular ejection fraction >30% scheduled for elective coronary artery bypass graft (CABG) surgery were included. Patients were randomized to receive 50 microg/kg of milrinone (n = 22) or placebo (n = 22) after aortic declamping. The flow in coronary artery bypass grafts was measured with a transit time flow meter at 10 minutes and 30 minutes after termination of CPB. The hemodynamic evaluation included transesophageal echocardiography, mean arterial pressure (MAP), heart rate, and intracavitary measurement of left ventricular end-diastolic pressure (LVEDP). The flow in the saphenous vein grafts was significantly higher in the milrinone group when compared with the placebo group both at 10 and 30 minutes after termination of CPB (p < 0.001). At 10 minutes, the flow was 64.5 +/- 37.4 mL/min (mean +/- standard deviation) and 43.6 +/- 25.7 mL/min in nonsequential vein grafts for milrinone and placebo, respectively. Corresponding values at 30 minutes were 54.8 +/- 29.9 mL/min and 35.3 +/- 22.4 mL/min. The left internal thoracic artery (LITA) flow was higher in the milrinone group but did not reach statistical significance. The fractional area change was higher, and the MAP and calculated pressure gradient (MAP-LVEDP) were lower at 10 minutes in the milrinone group. Milrinone significantly increases the flow in anastomosed saphenous vein grafts after CPB, and has beneficial effects on left ventricular function.

Skeletonization of the internal thoracic artery: a randomized comparison of harvesting methods

We performed a randomized study to compare internal thoracic artery (ITA) flow response to two harvesting methods used in the skeletonization procedure: ultrasonic scalpel and bipolar electrocautery. Sixty patients scheduled for CABG were randomized to receive either ultrasonically (n=30 patients) or electrocautery (n=30 patients) skeletonized ITAs. Intraoperative ITA graft mean flows were obtained with a transit-time flowmeter. ITA flows were evaluated at the beginning (Time 1) and at the end (Time 2) of the harvesting procedure. Post-cardiopulmonary bypass (CPB) flow measurement (Time 3) was obtained in the ITA grafts anastomosed to the left anterior descending artery. Intraoperative mean flow decreased significantly within ultrasonic group (Group U) and electrocautery group (Group E) at the end of the harvesting procedure (P<0.0001 in both cases). Within both groups the final mean flow measured on anastomosed ITAs (Time 3) was significantly higher than the beginning ITA flow value (Time 1). No statistical difference was noted comparing ITA flows between the two groups at any time of evaluation. Skeletonization harvesting of the ITA produces a modification of the mean flow. The quantity and the reversibility of this phenomenon, probably related to vasospasm, are independent from the energy source used in the skeletonization procedure.

Angiographic evidence for reduced graft patency due to competitive flow in composite arterial T-grafts

Composite arterial grafting causes splitting of internal thoracic artery flow to various myocardial regions. The amount of flow supplying each region depends on the severity of coronary stenosis. Competitive flow in the native coronary artery can cause occlusion or severe narrowing of the internal thoracic artery supplying this coronary vessel. Two hundred three consecutive postoperative coronary angiographies of 163 patients who underwent bilateral internal thoracic artery grafting using the composite-T-graft technique were analyzed. Angiographies were done in symptomatic patients or in patients with positive thallium scan between 2 and 102 months after surgery and were compared with preoperative angiograms. In 123 patients, both internal thoracic arteries were patent. The remaining 40 control patients had at least 1 nonfunctioning internal thoracic artery. A lower stenosis rate in the left anterior and circumflex arteries was associated with higher occlusion rate of the left internal thoracic artery (P < .005) and the right internal thoracic artery (P < .005), respectively. In 19 angiograms of 18 patients, graft failure could be related to competitive flow. This included 7 patients with disease of the left main artery and a preoperative stenosis degree ranging between 50% and 80%, 8 patients with moderate stenosis (70% or less) of the circumflex artery, and 3 with moderate stenosis of the left anterior descending artery. Three of the patients with disease of the left main artery, 2 of the patients with competitive flow in the circumflex artery, and all patients in the subgroup with left anterior descending arterial disease underwent percutaneous or surgical reintervention. The composite T-graft technique of bilateral internal thoracic artery grafting should be reserved for patients with severe (70% or more) left anterior descending and circumflex arterial stenosis.