Aortocoronary bypass graft patency assessed by coronary computed tomography angiography--unicentric study

Coronary artery bypass graft (CABG) surgery is used to revascularize ischemic myocaydium affected by coronary artery obstruction. Conventional coronary angiography (CCA) is an invasive method used for graft evaluation. Nowadays, in post CABG patients grafts can be assessed noninvasively by using coronary computed tomography angiography (CCTA).

AIM

To determine the late patency rate in coronary bypass grafts using CCTA.

METHODS

To assess graft patency, sixty post CABG patients (51/60 males and 9/60 females) were evaluated using dual source computed tomography (DSCT) angiography. All patients underwent a primary isolated CABG surgery between January 2000 and December 2004, performed by a single surgeon, at the Dartment of Cardiovascular Surgery, "Prof. Dr. George I. M. Georgescu" Institute for Cardiovascular Diseases, Iaşi, Romania. The grafts were classified as patent, occluded and stenotic (stenosis >50%).

RESULTS

The mean age of patients was 68.05-7.59 years and the mean time after graft implantation was 129.53-16.74 months. The number of assessed grafts was 200, including 146 saphenous vein grafts (SVG) and 54 in situ left internal mammary artery (LIMA) grafts. A total number of 105/146 (71.92%) venous grafts and 52/54 (96.3%) arterial grafts were patent.

CONCLUSION

Nowadays, computed tomography angiography is a modern noninvasive imaging modality used to evaluate the aortocoronary graft patency in early and late postoperative settings. In our study, the late saphenous graft patency rate was superior to that found in earlier angiographic studies.

The descending branch of the lateral femoral circumflex artery is a good option in CABG with arterial grafts

INTRODUCTION

The descending branch of the lateral femoral circumflex artery is an option for coronary artery bypass grafting.

OBJECTIVE

To evaluate the early patency and adaptation of lumen diameter using multidetector computed angiotomography.

METHODS

Thirty-two patients were selected to undergo coronary artery bypass grafting using the descending branch of the lateral circumflex artery, the internal thoracic artery, and other grafts. Evaluations were carried out through high resolution computed tomography performed on the 7th and 90th postoperative day. Diameters of the descending branch of the lateral circumflex artery and the left internal thoracic artery were measured 3 cm before the distal anastomosis, in the middle portion, and 3 cm after the proximal anastomosis. Diameters were compared using paired t-test (P<0.05).

RESULTS

Descending branch of the lateral femoral circumflex artery wDescending branch of the lateral femoral circumflex artery was used in 26 patients, as its use was not viable in six patients (18%). It was used as composite graft in all cases. The anterior descending branch was revascularized by the left internal thoracic artery in all cases. Patency rates of the descending branch of the lateral femoral circumflex artery were 96% and 92%, respectively. No occlusions were observed in the left internal thoracic artery (LITA) and no ischemic events were observed in the descending branch of the lateral circumflex. Descending branch of the lateral femoral circumflex artery increased the lumen diameter in the middle (P=0.001) and distal portions (P=0.006); the left internal thoracic artery (LITA) increased in the middle portion (P=0.001).

CONCLUSION

Similar to the left internal thoracic artery, the descending branch of the lateral femoral circumflex artery showed high patency rate and positive luminal adaptation. This early evaluation confirms the descending branch of the lateral femoral circumflex artery as a potential alternative for grafting. Due to anatomical variations, preoperative femoral angiographic evaluation appears to be mandatory.

Initial experience with internal mammary artery harvesting with the da Vinci Surgical System for minimally invasive direct coronary artery bypass

PURPOSE

We evaluated the feasibility of off-pump minimally invasive direct coronary artery bypass (MIDCAB) in combination with robotic harvesting of the left internal mammary artery (LIMA).

METHODS

Since 2004, 33 patients [average age, 64 years; 27 males (82%)] have undergone MIDCAB with robotic LIMA harvesting performed through the fourth or fifth intercostal space with guidance by enhanced computed tomography (CT).

RESULTS

No deaths or major adverse cardiac events occurred. Robotic LIMA harvesting was completed in 30 cases (91%), while three cases (9%) required conversion to a median sternotomy due to bleeding. The risk of LIMA injury significantly increased with age (p = 0.0012). For the 30 successful cases, the average harvest time was 68 min, and the average intraoperative blood loss was 306 ml, with only three patients (9%) requiring a transfusion. The graft flow was measurable in all cases (average, 34 ml/minute). All grafts were shown to be patent in postoperative evaluations, although CT revealed that the LIMA in one patient was anastomosed to an untargeted artery.

CONCLUSIONS

Off-pump MIDCAB in combination with robotic harvesting of the LIMA is a reasonable and less invasive procedure than the standard procedures. Potential problems include difficulty controlling bleeding from the graft, especially in elderly patients, and proper identification of the target artery.

Outcomes of off-pump coronary bypass grafting with the bilateral internal thoracic artery for left ventricular dysfunction

This study evaluated the outcomes of off-pump coronary artery bypass surgery (OPCAB) with severe left ventricular dysfunction using composite bilateral internal thoracic artery grafting. From January 2001 to December 2008, 1,842 patients underwent primary isolated OPCAB with composite bilateral internal thoracic artery grafting. A total of 131 of these patients were diagnosed with a severely depressed preoperative left ventricle ejection fraction (LVEF) (≤ 0.35). These patient outcomes were compared with the outcomes of 830 patients that had mildly or moderately depressed LVEF (0.36 to 0.59) and 881 patients with normal LVEF (>0.6). The early mortality for patients with severe LVEF was 2.3%. The 3-yr and 7-yr survival rate for patients with severe LV dysfunction was 86.0% and 82.8%, respectively. Multivariate analysis showed that severe LV dysfunction EF increased the risk of all-cause death (P=0.012; hazard ratio [HR],2.14; 95% confidence interval [CI],1.19-3.88) and the risk of cardiac-related death (P=0.008; HR,3.38; 95% CI, 1.37-8.341). The study identified positive surgical outcomes of OPCAB, although severe LVEF was associated with two-fold increase in mortality risk compared with patients who had normal LVEF.

Adoption and effectiveness of internal mammary artery grafting in coronary artery bypass surgery among Medicare beneficiaries

OBJECTIVES

The aim of this study was to assess the pattern of the adoption of internal mammary artery (IMA) grafting in the United States, test its association with clinical outcomes, and assess whether its effectiveness differs in key clinical subgroups.

BACKGROUND

The effect of IMA grafting on major clinical outcomes has never been tested in a large randomized trial, yet it is now a quality standard for coronary artery bypass graft (CABG) surgery.

METHODS

We identified Medicare beneficiaries ≥66 years of age who underwent isolated multivessel CABG between 1988 and 2008, and we documented patterns of IMA use over time. We used a multivariable propensity score to match patients with and without an IMA and compared rates of death, myocardial infarction (MI), and repeat revascularization. We tested for variations in IMA effectiveness with treatment × covariate interaction tests.

RESULTS

The IMA use in CABG rose slowly from 31% in 1988 to 91% in 2008, with persistent wide geographic variations. Among 60,896 propensity score-matched patients over a median 6.8-year follow-up, IMA use was associated with lower all-cause mortality (adjusted hazard ratio: 0.77, p < 0.001), lower death or MI (adjusted hazard ratio: 0.77, p < 0.001), and fewer repeat revascularizations over 5 years (8% vs. 9%, p < 0.001). The association between IMA use and lower mortality was significantly weaker (p ≤ 0.008) for older patients, women, and patients with diabetes or peripheral arterial disease.

CONCLUSIONS

Internal mammary artery grafting was adopted slowly and still shows substantial geographic variation. IMA use is associated with lower rates of death, MI, and repeat coronary revascularization.

Bilateral internal thoracic artery harvest and deep sternal wound infection in diabetic patients

BACKGROUND

Coronary artery bypass graft surgery is superior to percutaneous intervention in diabetic patients with multivessel disease. The use of bilateral internal thoracic arteries (BITA) may provide better long-term graft patency, but the risk of postoperative deep sternal wound infection has limited its use in diabetic patients. However, studies have reported conflicting results, and require systematic evaluation.

METHODS

MEDLINE, EMBASE, World of Science, and the Cochrane library were searched for randomized controlled trials and observational studies comparing the incidence of deep sternal wound infection in diabetic patients undergoing either left internal thoracic artery (LITA) or BITA harvest. We used random effect models to compare risk ratios within groups.

RESULTS

One randomized controlled trial and 10 observational studies (126,235 diabetic patients: 122,465 LITA, 3,770 BITA) met inclusion criteria. Deep sternal wound infection occurred in 3.1% and 1.6% for the BITA and LITA cohorts, respectively. The risk ratio for deep sternal wound infection development was 1.71 (1.37 to 2.14) for BITA compared with LITA. Patients who underwent skeletonized BITA harvest had a similar risk of deep sternal wound infection compared with LITA (0.9 [0.42 to 2.09]), although pedicled harvest demonstrated increased risk (1.77 [1.4 to 2.23]). Early mortality was comparable in the LITA cohort (2.5%) and the BITA cohort (2.3%; p = 0.8).

CONCLUSIONS

The risk of deep sternal wound infection can be minimized in diabetic patients undergoing coronary artery bypass graft surgery by performing ITA harvested in a skeletonized manner with meticulous attention to preserving sternal blood flow. Pedicled harvest is to be discouraged when utilizing both ITA owing to a significant increase in the risk of postoperative deep sternal wound infection.

Transthoracic Doppler echocardiography of the left internal mammary artery graft

Assessment of the left internal mammary artery (LIMA) graft patency currently requires invasive investigation through coronary angiography. In the last years the successful application of noninvasive Doppler spectrum analysis has been reported for patency assessment of the LIMA graft after myocardial revascularization. Echocardiography is considered to be a sensitive noninvasive screening modality to diagnose critical narrowing of LIMA grafts and angiography should be reserved for cases in which Doppler echocardiography fails to visualize the LIMA or reveals an abnormal flow pattern.

[Intraoperative assessment of composite bypass grafts by means of ultrasonic Doppler flowmetry]

The use of the both internal thoracic arteries while forming a composite bypass graft has been suggested as a method making it possible to carry out total myocardial revascularization. However, controversial still remain the problem of the distribution of blood in these bypass grafts, as well as that concerning T-grafts' capability of providing the sufficient blood inflow to the basin of the coronary arteries being bypassed. The method of ultrasonic Doppler flowmetry was used to perform the intraoperative assessment of 59 composite bypass grafts along such parameters as the pulsatility index (PI), mean volume blood flow velocity (Qmean), and percentage of diastolic volumetric filling (DF). The obtained findings were statistically processed making it possible to obtain the average parameters of blood flow for the composite bypass grafts and their branches. A dependence was established between blood flow distribution in the composite conduit and the degree of the lesion of the artery being bypassed.

In vitro effects of lidocaine hydrochloride on coronary artery bypass grafts

AIM

Coronary artery bypass grafting (CABG) is one of the most common procedures performed to improve blood supply to myocardium. The characteristics of grafts, mechanical stress and pharmacological agents have substantial influence on the short and long term graft patency. Lidocaine is among the most frequently used antiarrhythmic agents perioperatively. The aim of this study was to evaluate the in vitro effects of lidocaine on internal mammarian artery (IMA), radial artery (RA) and saphenous vein (SV) grafts.

METHODS

Using standard tissue bath techniques, responses to increasing concentrations of lidocaine hydrochloride were obtained, in segments of IMA, RA and SV grafts. Twenty patients were enrolled in the study with a total number of 48 grafts (16 for IMA, RA and SV grafts each). In vitro lidocaine concentrations between 10(-9)M and 10(-3.5)M were studied to represent therapeutic plasma concentration of 1.5-5 mcg/mL.

RESULTS

In IMA and RA grafts, lidocaine hydrochloride caused vasodilatation (40.5±1.9% and 39.1±2.6 % respectively) at concentrations between 10(-9) to 10(-7.5) M while causing a dose dependent vasoconstriction response at concentrations above 10(-7.5) M. In SV graft samples, lidocain hydrochloride caused vasodilatation (24.4±1.9 %) at concentrations between 10(-9) to 10(-7) M while causing dose dependent vasoconstriction at concentrations above 10(-7) M. For vasoconstriction effect, mean±SD values for E(max) were calculated as: 120.1±6.6% in IMA, 83.35±5.06% in RA, and 154.0±13.8% in SV. The vasoconstriction in the SV samples was higher than in the RA and IMA. The mean ±SD LogEC(50) values were -5.15±0.27, -5.76±0.11 and -5.56±0.19 for SV, IMA and RA grafts respectively.) There was a statiscally significant differences in the Log EC(50) values between SV, IMA and RA (P<0.005)

CONCLUSION

Based on the results of our study, we conclude that, increasing doses of lidocaine in the perioperative period may cause vasospasm in IMA, RA and SV grafts. Thus, avoiding high doses may have a role in improving perioperative and long term mortality.

[Single versus bilateral internal thoracic artery grafts for multi vessel coronary artery bypass grafting: mid-term results]

BACKGROUND

The issue of superiority of single internal thoracic artery grafting versus bilateral internal thoracic artery grafting remains unresolved.

AIM

The aim of this study was to compare the early results and midterm outcome of single and bilateral internal thoracic artery grafting for multivessel coronary artery bypass grafting.

METHODS

Between January 2005 and March 2010, 196 patients underwent primary coronary artery bypass grafting with at least one internal thoracic artery grafts. Early results and Outcomes of patients undergoing single internal thoracic artery (SIMA) plus saphenous vein grafting (n=145) and bilateral internal thoracic artery (BIMA) plus saphenous vein grafting (n=51) were obtained at a mean followup of 29 months.

RESULTS

Patients with bilateral internal thoracic artery grafting were younger, had less hypertension, higher left main disease and better Euroscore than patients undergoing single internal thoracic artery grafting. In-hospital mortality was similar for the two groups: 6.9 % for patients undergoing SIMA versus 5.9 % for those undergoing BIMA (p=0.8). Sternal wound infection was also similar (2.8% versus 3.9% p=0.68). Mid-term mortality was (4% VS 4.8% p=0.71) and event free survival probability at 28 months was 75% for the single-graft group compared with 85.7% for the bilateral-graft group (P =0.46).

CONCLUSION

Our study found similar early and mid-term clinical outcomes for patients undergoing SIMA plus saphenous vein grafting and those undergoing BIMA plus saphenous vein grafting for multivessel coronary artery bypass grafting.

'No-touch' saphenous vein harvesting improves graft performance in patients undergoing coronary artery bypass surgery: a journey from bedside to bench

The saphenous vein is the most commonly used conduit in patients undergoing coronary artery bypass surgery yet its patency is inferior to the internal thoracic artery. Vascular damage inflicted to the vein when using conventional harvesting techniques affects its structure. Endothelial denudation is associated with early vein graft failure while damage of the outermost vessel layers has adverse long-term effects on graft performance. While many in vitro and in vivo experimental studies aimed at improving vein graft patency have been performed to date no significant 'bench to bedside' advances have been made. Among experimental strategies employed is the use of pharmacological agents, gene targeting and external stents. A 'no-touch' technique, where the saphenous vein is removed with minimal trauma and normal architecture preserved, produces a superior graft with long term patency comparable to the internal thoracic artery. Interestingly, many experimental studies are aimed at repairing or replacing those regions of the saphenous vein damaged when harvesting conventionally. 'No-touch' harvesting is superior in coronary artery bypass patients with long-term data published 5years ago. Here we describe a 'bedside to bench' situation where the mechanisms underlying the improved performance of 'no touch' saphenous vein grafts in patients have been studied in the laboratory.

Short-term complications after bilateral internal mammary artery grafting--a retrospective study

OBJECTIVES

To analyze our experience of conducting Bilateral Internal Mammary Artery (BIMA) grafting, using both pedicled and free grafts for coronary revascularization, assessing the safety and efficacy of the procedure and comparing any differences observed between the two techniques of harvesting the grafts.

METHODS

A retrospective cross sectional study was conducted in July 2010 in which all 48 patients undergoing bilateral internal mammary artery grafting for coronary bypass surgery at the Aga Khan University Hospital from 1996 to 2010 were reviewed and evaluated. The main outcome measures were perioperative mortality and early morbidity with particular reference to cerebrovascular accidents, sternal wound complications and re-opening for bleeding. Chi-square test was used to elicit any meaningful associations between patient characteristics and post-operative outcomes.

RESULTS

Of the 48 patients undergoing bilateral IMA grafting, 46 were males and 2 females. The mean age was 48 +/- 9.4 years. Dyslipidaemia and smoking were the most common identifiable risk factors for coronary vascular disease. Following the 40 elective and 8 emergent surgeries, there was one hospital death. The most common post-operative complications were arrhythmias and wound infection. Diabetes and obesity were not observed to be associated with an increased risk of developing surgical site infection.

CONCLUSIONS

Our study suggests that the short-term efficacy and the safety profile of bilateral IMA grafting for coronary revascularization is clinically acceptable. Long-term follow-up studies should be done to assess the cardiac event-free survival of these individuals evaluating its applicability as a routine for coronary artery bypass grafting in Pakistan.

Role of internal mammary artery bypass grafts in retrograde chronic total occlusion interventions

The role of internal mammary artery grafts in facilitating retrograde chronic total occlusion interventions is controversial. We describe two cases demonstrating: (a) retrograde wiring via a left internal mammary artery graft; and (b) using the left internal mammary graft for vessel visualization while retrograde crossing to the right coronary artery was achieved via the native left main coronary artery (triple arterial access). The internal mammary artery grafts can facilitate retrograde chronic total occlusion interventions, but should be used with caution to minimize the risk of injury.

How to use the left internal thoracic artery which has been damaged during harvesting?

The established superiority of the internal thoracic artery as a coronary arterial conduit has led to its mandatory use in coronary artery bypass grafting surgery. Therefore, the damage of the internal thoracic artery during harvesting is an abysmal complication, after which the conduit is usually discarded. An alternative approach is presented here, which has allowed us to use the distal two thirds of the proximally damaged left internal thoracic artery as an in situ (with retrograde blood supply from superior epigastric and musculophrenic arteries), reversed arterial conduit to revascularize the left anterior descending coronary artery.

Effect of the degree of LAD stenosis on "competitive flow" and flow field characteristics in LIMA-to-LAD bypass surgery

The long-term patency of the left internal mammary artery (LIMA) in left anterior descending (LAD) coronary stenosis bypass surgery is believed to be related to the degree of competitive flow between the LAD and LIMA. To investigate the effect of the LAD stenosis severity on this phenomenon and on haemodynamics in the LIMA and anastomosis region, a numerical LIMA-LAD model was developed based on 3D geometric (obtained from a cast) and hemodynamic data from an experimental pig study. Proximal LAD pressure was used as upstream boundary condition. The model counted 13 outlets (12 septal arteries and the distal LAD) where flow velocities were imposed in systole, while myocardial conductance was imposed in diastole via an implicit scheme. LAD stenoses of 100 (total occlusion), 90, 75 and 0 % area reduction were constructed. Low degree of LAD stenosis was associated with highly competitive flow and low wall shear stress (WSS) in the LIMA, an unfavourable hemodynamic regime which might contribute to WSS-related remodelling of the LIMA and suboptimal long-term LIMA bypass performance.

Are two internal thoracic artery grafts as safe as one? Experience from Green Lane Hospital

AIM

To compare short-term mortality and major morbidity between patients undergoing elective primary isolated CABG with bilateral internal thoracic artery (BITA) or single internal thoracic artery (SITA) grafts at Green Lane Hospital (Auckland, New Zealand).

METHODS

We conducted a retrospective study of short-term outcomes in 5955 patients receiving SITA and 637 patients receiving BITA grafts between 1990 and 2004. Only patients undergoing elective primary isolated coronary artery surgery were included. The primary outcome was a composite end-point (early death, perioperative MI, reoperation for sternal wound complications or significantly prolonged hospital stay). Patients receiving BITA grafts were case-matched with patients receiving SITA grafts for confounding factors and comparison was made between perioperative outcomes in the two groups.

RESULTS

After case-matching, no statistically significant difference was found in the incidence of our primary endpoint between patients receiving BITA versus SITA grafts [odds ratio 0.84 (95% CI 0.59, 1.21)]. Furthermore, there was no difference in rates of reoperation for sternal wound complications between the two groups [odds ratio 1.00 (95% CI 0.29, 3.44)].

CONCLUSIONS

Given the potential long-term clinical advantages of BITA grafting, our results support the increased use of BITA grafts in selected patients.

Anterograde flow compromise of a patent left internal mammary artery graft from a proximal subclavian artery stenosis. Myocardial ischemia not driven by the coronary-subclavian steal syndrome mechanism

A 54-year male with previous triple vessel coronary artery and aorto-bi-femoral bypass graft surgeries complained of crescent angina. Stress induced myocardial ischemia on echocardiography was demonstrated. We performed direct stenting of a saphenous vein graft to the right coronary artery, via right radial approach. Subsequently stenting of a severe left subclavian artery proximal stenosis was performed via right brachial approach in order to relieve an overt myocardial ischemia in the territory supplied by a patent left internal mammary artery graft originated distally to the left subclavian stenosis. The finding of a total left axillary artery occlusion complement the pathogenesis of myocardial ischemia produced by limited anterograde flow and not driven by the common flow reversal mechanism of a typical coronary-subclavian steal syndrome.