In-situ left-sided bilateral internal thoracic artery: elevated hemidiaphragm.

Background Procurement of the internal thoracic artery risks ipsilateral phrenic nerve injury and elevated hemidiaphragm. Anatomical variations increase the risk on the right side. Patients receiving left-sided in-situ right internal thoracic artery configurations appear to be at greatest risk. Methods From 2014 to 2016, 432 patients undergoing left-sided in-situ bilateral internal thoracic artery grafting were grouped according to right internal thoracic artery configuration: retroaortic via transverse sinus (77%) or ante-aortic (23%); targets were the circumflex and left anterior descending artery territories, respectively. Elevated hemidiaphragm was assessed by serial chest radiographs and categorized by side, complete (≥2 intercostal spaces) versus partial, and permanent versus transient. Results Right elevated hemidiaphragm occurred in 4.2% of patients. The incidence of radiological complete right elevated hemidiaphragm was 2.8% (12/432); 8 cases were transient with recovery in 3.5 ± 0.3 weeks. Permanent right elevated hemidiaphragm occurred in 0.9% (retroaortic group only). Permanent left elevated hemidiaphragm occurred in 0.9% and was significantly higher in the ante-aortic group (3/99 vs. 1/333, p = 0.039). No bilateral hemidiaphragm elevation was documented. Partial right elevated hemidiaphragm occurred in 1.4% and was not associated with adverse early or late respiratory outcomes. Conclusions Despite susceptible right phrenic nerve-internal thoracic artery anatomy, the incidence of permanent right elevated hemidiaphragm is low and no higher than left-sided in prone bilateral internal thoracic artery subsets. This reflects skeletonized internal thoracic artery procurement. Although statistical significance was not achieved, a retroaortic right internal thoracic artery configuration may constitute a higher risk of right phrenic nerve injury.

The physiologic and histologic properties of the distal internal thoracic artery and its subdivisions.

OBJECTIVE: We compared the flow rates, reactivity, and morphology of the distal internal thoracic artery and its branches, the superior epigastric and musculophrenic arteries, to test their applicability as possible conduits in coronary artery bypass grafting surgeries. METHODS: Skeletonized internal thoracic artery and subdivisions of patients undergoing coronary artery bypass grafting were studied intraoperatively (n = 100) for flow and length measurements and in vitro in organ baths (n = 58) for active response to norepinephrine. Quantitative microscopic analysis of the muscle density and degree of intimal hyperplasia was performed. Results were analyzed according to age, gender, risk factors, and medications. RESULTS: Internal thoracic artery subdivisions contributed an average extra length of 2 cm. Free flow rates were 129 ± 45 mL/min, 114 ± 41 mL/min, and 93 ± 36 mL/min in the internal thoracic artery, superior epigastric artery, and musculophrenic artery, respectively. Sternum and internal thoracic artery length and free flow rates were significantly lower in women. The subdivisions were significantly more reactive to norepinephrine than the distal internal thoracic artery (P ∼ .005), although sensitivity to norepinephrine was similar. Patients treated with beta-blockers had significantly decreased reactivity (P = .009). Microscopic analysis suggests similar muscle content in the internal thoracic artery and subdivisions. Eccentric (28%) and concentric (62%) intimal hyperplasia were observed in 90% of specimens, with no evidence for atherosclerotic plaques. There was no significant difference in the degree of intimal hyperplasia between the distal internal thoracic artery and its subdivisions, and there was no correlation to risk factors. CONCLUSIONS: Our results confirm the previous studies on the higher contractility in internal thoracic artery subdivisions, suggesting caution in the use of the bifurcation for revascularization. However, the extra length, sufficient flow, and favorable histologic properties suggest that the bifurcation may be appropriate for coronary revascularization in selected cases.

Retroaortic right internal thoracic artery grafting of circumflex artery targets.

BACKGROUND: Retroaortic right internal thoracic artery grafting has failed to gain popularity. We aimed to delineate patient correlates of eligibility, distribution of targets, and effects of target remoteness on outcome and risk of retroaortic bleeding. METHODS: Data of 861 patients undergoing skeletonized bilateral internal thoracic artery grafting (2007-2012) were analyzed according to retroaortic (n = 300) or T-graft configuration. Retroaortic graft subgroups were categorized according to proximal (first obtuse marginal, ramus) or distal (2nd, 3rd, or sequential 1st-2nd obtuse marginal) circumflex artery targets. RESULTS: LOESS curve analyses revealed that taller patients had a higher likelihood of retroaortic grafting. The distribution of 337 retroaortic graft targets (300 patients) was first obtuse marginal in 74.5%, 2nd marginal in 12.4%, ramus in 11.2%, 3rd marginal in 1.9% and sequential 1st-2nd marginal in 12.3%. The success rate in reaching proximal and distal circumflex artery targets was 97% and 30%, respectively, 5-year survival (92.2%) and freedom from major adverse cardiac and cerebrovascular events (85.8%) were comparable between proximal and distal retroaortic graft subgroups. Distal circumflex artery targets had no effect on the occurrence of major adverse cardiac and cerebrovascular events. The incidence of retroaortic bleeding from skeletonized retroaortic grafts was 0.6%. CONCLUSIONS: Taller patients have a greater likelihood of qualifying for retroaortic grafting. This technique is highly reproducible for proximal but not distal circumflex artery targets. Distal circumflex artery targets are not independent correlates of early or late adverse outcomes. The risk of retroaortic bleeding is low despite retroaortic right internal thoracic artery skeletonization.

Concomitant grafting of both postbifurcation internal thoracic artery branches.

OBJECTIVE: We aimed to assess the clinical outcome and graft patency after concomitant grafting of both postbifurcation internal thoracic artery (ITA) branches. METHODS: Between 2007 and 2013, 17 patients (14 men; mean [SD] age, 60 [9.3] years) underwent skeletonized bifurcated ITA grafting. Respective targets were restricted to non-left anterior descending (LAD) area. In all patients, a complementary standard ITA was used to graft the LAD artery. Graft patency was assessed by standard coronary angiography or serial multidetector computed tomography. RESULTS: Of the bifurcated conduits, 94% were right ITA. Respective right ITA target sets were first and second obtuse marginal arteries (M1-M2) (n = 12), ramus-M1 (n = 2), and distal right coronary artery-posterior descending artery (n = 2). Right ITAs were mobilized retroaortic (via the transverse sinus) in 14 patients (82%) (to circumflex artery targets). Circumflex artery targets comprised 88.2% of all anastomoses (30/34). There were no early mortalities, myocardial infarctions, or hypoperfusion syndromes. During median follow-up of 44 months (range, 3-63), there was no late mortality. Overall reintervention rate was 11.7%, and bifurcated ITA-related reintervention rate was 5.8%. At 5 years, freedom from major adverse cardiac or cerebrovascular event related to bifurcated ITA respective territory was 87% (Kaplan-Meier). Coronary imaging was achieved in 76% of the patients (elective multidetector computed tomography, n = 9; symptoms-directed coronary catheterization, n = 4). Bifurcation branch patency rate was 88.4% (23/26) at a median of 3.5 years. CONCLUSIONS: Grafting both postbifurcation ITA branches is technically feasible and may be selectively considered. Current observations are valid for skeletonized conduits and limited to non-LAD targets. These preliminary findings should be corroborated by larger data sets.

Bilateral internal thoracic artery grafting in insulin-treated diabetes.

BACKGROUND: We sought to assess the risk and late outcome of bilateral internal thoracic artery grafting in eligible insulin-treated diabetic subsets. METHODS: 147 insulin-treated diabetic patients undergoing arterial revascularization were grouped as: skeletonized bilateral internal thoracic artery (n = 83) or internal thoracic artery-radial artery (n = 64). Chronic lung disease or overweight and female constituted exclusion criteria for bilateral internal thoracic artery grafts. RESULTS: Patients who had bilateral internal thoracic artery grafts were younger and comprised fewer females. Left-sided bilateral internal thoracic artery configurations were predominantly applied. Despite mean hemoglobin A1c of 8.0% ± 1% (range, 7%-13.5%) respective rates of deep sternal infection in bilateral internal thoracic artery and radial artery patients were 1.2% and 0%; superficial wound infection occurred in 3.1% and 3.6%, respectively. One sternoplasty was performed. Bilateral internal thoracic artery grafting did not correlate with sternal complications (odds ratio = 2.24, 95%CI: 0.56-8.95, p = 0.256). Of the radial artery conduits, 98% were adequate, and procurement-site complications occurred in 3.1%. Follow-up was 2-58 months (median, 25 months). Five-year survival was comparable in the 2 groups (p = 0.360). Bilateral internal thoracic artery grafting did not reduce late major adverse cardiac events (p = 0.729) or late mortality (p = 0.384). CONCLUSIONS: Skeletonized bilateral internal thoracic artery grafts can be used with acceptable risk in a substantial portion of insulin-treated diabetic patients, so it should not be automatically denied, but the choice of such grafts is not associated with midterm cardiac benefits.

Correlation between atrial ZnT-1 expression and atrial fibrillation in humans: a pilot study.

BACKGROUND: Until recently, the membrane protein ZnT-1 was studied mainly in the context of zinc homeostasis. However, new findings indicate that it acts as an inhibitor of L-type calcium channels. We recently found that acute rapid pacing of the rat atria in vivo augments the expression of ZnT-1, while knockdown of ZnT-1 in culture can oppose the inhibition of L-type calcium channels following rapid pacing. This pilot study, the first to assess cardiac ZnT-1 in humans, was designed to look for possible correlation between the atrial expression of ZnT-1 and atrial fibrillation. METHODS: Right atrial appendage tissue was collected from 39 patients (27 with sinus rhythm and 12 with atrial fibrillation; 6-permanent, 6- paroxysmal or persistent) undergoing open-heart surgery. The expression of ZnT-1 was analyzed by Western blot utilizing beta-actin as an internal loading control and a standard rat heart sample (STD) for inter-blot comparison. RESULTS: Overall atrial fibrillation patients (n = 12) had median ZnT-1/beta-actin of 1.80 STD (inter-quartile range 1.26 to 2.85) versus 0.73 STD (0.24 to 1.64) in the sinus rhythm group (P = 0.002). No association was found between ZnT-1 level and most other clinical parameters tested. Multivariate analysis determined that atrial fibrillation and increased body mass index were the only independent variables clearly associated with higher ZnT-1 levels (Standardized coefficients Beta = 0.62, 0.31; P = 0.002, P = 0.04, respectively). CONCLUSIONS: This pilot study provides evidence for increased ZnT-1 expression in the atria of patients with atrial fibrillation.

Repeat median sternotomy after prior ante-aortic crossover right internal thoracic artery grafting.

BACKGROUND: In situ bilateral internal thoracic artery (ITA), with ante-aortic crossover right ITA (RITA) is gaining popularity. However, the retrosternal position of the crossover RITA has raised concerns with regard to its compromise during subsequent resternotomy. METHODS: Ten patients underwent repeat median sternotomy after prior ante-aortic crossover RITA grafting. Specific RITA routing and fixation had been performed in the initial operation. Preoperative imaging, including computed tomography (CT) angiography, was performed to confirm RITA position in relation to the sternum and assess feasibility. RESULTS: Resternotomy was performed 4-48 months after the initial operation (median, 22 months). Nine crossover RITA grafts were functioning at the time of resternotomy. CT angiography was performed in four patients in whom the premarked RITA could not be localized on the plain chest radiograph. The feasibility of conducting a nonmodified resternotomy was determined based on preoperative imaging. All RITA grafts resumed their original position and none was injured during reentry. There was no early mortality, perioperative stroke, or reexploration for bleeding. One patient sustained myocardial infarction, however, not in a RITA-related distribution. CT angiography was predictive in confirming a free retrosternal space. CONCLUSIONS: Resternotomy after prior ante-aortic crossover RITA grafting can be performed at acceptable risk. Confirmation of a free retrosternal space by preoperative imaging may contribute to the safety of the procedure. Maneuvers performed during the first operation are useful in preventing RITA adherence to the sternum.

Reduced strokes in the elderly: the benefits of untouched aorta off-pump coronary surgery.

BACKGROUND: Avoiding aortic manipulation during off-pump coronary artery bypass (OPCAB) reduces the risk for atheroembolic complications and may, thus, benefit elderly patients who are prone to atherosclerotic aortic involvement. METHODS: During a period of 18 months (2000-2002), 160 consecutive OPCAB patients older than 75 years were evaluated. One hundred and three patients undergoing clampless OPCAB were compared to 57 patients in whom side clamps were applied. Clampless revascularization was achieved by in situ or T-graft arterial configurations. RESULTS: Mean age was older (79.3 years vs 78.2, p = 0.049) and the prevalence (43% vs 7%, p < 0.0001) and severity of aortic disease was higher in the clampless group. The main conduits used were bilateral skeletonized internal thoracic artery (47%) and radial arteries (42%). More grafts were performed in the side-clamp group (2.5 +/- 0.5 vs 2.3 +/- 0.6, p = 0.023), however, revascularization of the postero-lateral territory was comparable. While early mortality (2.9% vs 7%, p = >or=0.05), perioperative myocardial infarction (3% vs 5%, p = >or=0.05), and sternal infections (none) were similar, the incidence of major neurological complications (0% vs 5.3%, p = 0.044) and the combined outcome of stroke or mortality (3% vs 12%, p = 0.035) were lower in the clampless group. Multivariate analysis identified side clamping as a predictor for the occurrence of stroke or mortality (OR, 6.28, CL 1.39-28.4, p = 0.017), increasing this risk by sixfold. CONCLUSIONS: Clampless OPCAB is associated with reproducible neurological benefit. Improved neurological outcome may be conferred irrespective of the method of aortic screening in patients 75 years or older. The use of arterial conduits for this purpose is feasible despite the patients' advanced years.

Bilateral internal thoracic artery grafting in insulin-treated diabetics: should it be avoided?

BACKGROUND: It has been advocated that skeletonized bilateral internal thoracic artery (BITA) grafting may be implemented safely in diabetics, thus bestowing these patients with the long-term benefits of this strategy. However, the feasibility of this approach in insulin-treated patients has yet to be determined. METHODS: One-hundred twenty-four insulin-treated diabetics, operated on between April 1996 and December 2001, were compared according to the surgical technique used: BITA (n = 50) or single internal thoracic artery (SITA; n = 74). In the latter, complementary grafts used were saphenous veins and radial arteries. RESULTS: The groups had comparable risk profiles, with the exception of more neurologic events in the SITA group (21% vs 4%, p = 0.008). There was no significant difference in 30-day mortality (6% vs 4%, p = 0.684), nor in the incidence of neurologic complications (2% vs 8%, p = 0.240). The rate of sternal infection was comparable (4% vs 2.7%, p = 1.000). Use of BITAs was associated with a lower return of angina (4% vs 20%, p = 0.025), less cardiac events (17% vs 38%, p = 0.01), and reduced cardiac mortality (none vs 10%, p = 0.04). Despite the similar 6-year survival (80.5% and 77.4%, p = NS), cardiac-related event-free survival was better in BITA patients (69% vs 23%, p < 0.0001). Multivariate analysis identified use of BITA as a protective factor resulting in less return of angina (p = 0.007) and improved cardiac-related event-free survival (p = 0.001). CONCLUSIONS: Skeletonized BITA grafting can be performed in insulin-treated diabetics at acceptable risk. This approach may confer improved cardiac outcome. Thus, it should be considered in selected patients.

'No touch' techniques for porcelain ascending aorta: comparison between cardiopulmonary bypass with femoral artery cannulation and off-pump myocardial revascularization.

BACKGROUND: Detection of severe atherosclerotic ascending aorta during coronary artery bypass grafting requires alterations in the standard surgical technique to reduce the probability of stroke-related atheroembolization. Off-pump coronary artery bypass grafting (OPCAB) confers the benefits of avoiding aortic cannulation and clamping, and may therefore attenuate this risk. METHODS: OPCAB (n = 41) was compared to cardiopulmonary bypass (CPB) using femoral arterial cannulation and hypothermic fibrillatory arrest (n = 15), in patients with porcelain ascending aorta undergoing myocardial revascularization. In both groups, a 'no touch' technique was applied by avoiding aortic cannulation and clamping. Proximal anastomoses on the atherosclerotic aorta were avoided by arterial grafting, (in-situ or T-graft configurations) in all cases. RESULTS: Operative mortality was comparable (2.4% and 6.6% in the OPCAB and CPB groups respectively, p = NS). The rate of adverse neurological events, (two strokes and one transient ischemic attack), was higher in the CPB group (p = 0.0164). Based on brain CT, the nature of the recorded stroke suggested retrograde emboli. Three year survival (Kaplan-Meier) for the OPCAB and CPB groups was 86.7% and 81.3%, respectively (p = NS). Occurrence of late neurological adverse events during follow-up (8-51 months) was similar. CONCLUSIONS: In patients with porcelain ascending aorta undergoing myocardial revascularization, neurological outcome of OPCAB patients is better than CPB using femoral artery cannulation.