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The authors describe a case in which the dominant blood supply to a subperiosteally-harvested serratus anterior muscle and rib composite myoosseous free flap came from the lateral thoracic artery. There were no other associated features in this patient to warn of the vascular variant. Reconstructive surgeons should be aware of possible variations in the vascular anatomy of this flap.
BACKGROUND: Arterial spasm is described as an event occurring after left internal thoracic artery (LITA) harvesting. Many vasodilators have been used to treat or prevent LITA spasm. The aim of this study is to compare the effects between glyceril-trinitrate/verapamil (GV) solution and papaverine to treat LITA spasm and to determine the best delivery method. METHODS: One hundred consecutive ischemic patients were randomly assigned to three groups: group GV (n = 34, GV solution), group P (n = 33, papaverine), or group C (n = 33, normal saline). In each patient, pedicled LITA was harvested, thereafter sprayed with the randomized solution, and covered with a sponge. Fifteen minutes after heparin administration, LITA was distally divided; flow per minute was calculated after measuring the free flow for over 15 seconds; this is named "topical free flow." Then, the vasodilator was injected intraluminally and free flow per minute was measured; this is called "intraluminal free flow." RESULTS: Analysis of variance was applied to detect differences among groups; paired-sample t test was used for LITA topical free flow versus intraluminal free flow within single groups. Mean LITA free flows were as follows: group GV, topical free flow = 38.6 +/- 25.2 mL/min versus intraluminal free flow = 58.8 +/- 29 mL/min (p < 0.0001); group P, topical free flow = 45.4 +/- 38.9 mL/min versus intraluminal free flow mL/min (p < 0.0001); group C, topical free flow = 31.6 +/- 19.9 mL/min versus intraluminal free flow = 34 +/- 19.8 mL/min (p = 0.14). Topical free flow difference among the three groups was not statistically significant (p = 0.1); intraluminal free flow difference was statistically significant (p = 0.001). Intraluminal free flow in group GV and in group P were higher than intraluminal free flow in group C (p = 0.004 and 0.001, respectively). Intraluminal free flow of group P was higher than that of group GV; this difference did not reach statistical significance (p = 1.00). CONCLUSIONS: Glyceril-trinitrate/verapamil solution and papaverine are able to treat the spasm and increase the flow of the LITA, when they are used intraluminally. When used topically, these vasodilator agents do not ensure an optimal free flow.
The number of patients undergoing combined aortic valve replacement (AVR) for aortic stenosis (AS) and coronary artery bypass grafting (CABG) has been increasing. In CABG, the internal thoracic artery (ITA) is the preferred conduit for its long-term patency. Although Doppler studies on ITA have been widely used, flow characteristics of the vessel in patients with AS have not been reported. To evaluate blood flow pattern of the ITA in AS, duplex scanning was performed in 10 patients before and after AVR. Peak systolic velocity was measured, and blood flow was calculated from mean velocity and cross-sectional area. The mean diameters of the vessels were approximately 1.8 mm on both sides. AVR caused an increase in systolic velocities from 61.2 cm/sec to 85.5 cm/sec in right ITA and from 58.4 cm/sec to 84.7 cm/sec in left ITA. The flow volumes increased from 32.2 ml/min to 46.7 ml/min in right and increased from 31.6 ml/min to 46.3 ml/min in left after AVR. In simultaneous AVR for AS and CABG, suitability of the ITA should be assessed before its use, and concomitant AVR may be quite important to provide adequate flow of the ITA as a conduit.
BACKGROUND: Internal thoracic artery (ITA) malperfusion has been described as a potentially devastating and lethal complication of coronary artery bypass grafting (CABG). It is our practice to perform an additional vein graft to the distal left anterior descending (LAD) artery in such cases. METHODS: From August 1999 to July 2002, 2877 CABG procedures were performed at our institution. In 65 patients (2.3%) ITA malperfusion was observed. All of them were treated with an additional vein graft to the distal LAD. All patient data were screened for the time interval between the occurrence of ITA malperfusion and the decision to perform an additional vein graft. RESULTS: Of 65 patients with ITA malperfusion, 54 patients (83%) survived (group 1), 11 patients (17%) died (group 2). There was no difference in preoperative risk status between the groups. Cross clamp time was 88 +/- 4 minutes in group 1 and 104 +/- 11 minutes in group 2 (p = 0.04). Intraoperative ITA flow to LAD was 6 +/- 1 mL/min in group 1 and 10 +/- 5 mL/min in group 2 (p = 0.2). Time between release of cross clamp and second period of cross clamping was 50 +/- 5 minutes in group 1 and 75 +/- 11 minute group 2 (p = 0.02). Time between termination of cardiopulmonary bypass (CPB) and second period of cross clamping was 23 +/- 3 minutes in group 1 and 46 +/- 7 minutes in group 2 (p = 0.003). Vein graft flow to distal LAD was 54 +/- 4 mL/min in group 1 and 52 +/- 12 mL/min in group 2 (p = 0.5). Maximum postoperative troponin I was 35 +/- 11 ng/mL in group 1 and 136 +/- 32 in group 2 (p = 0.003). CONCLUSIONS: Survivors of ITA malperfusion had shorter cross clamp times and less myocardial damage as evidenced by lower postoperative troponin I levels. Time intervals between first and second cross clamp and between termination of CPB and second cross clamp were lower in survivors, thus indicating that a fast decision for an additional vein graft may influence postoperative patient outcome.
BACKGROUND: Use of bilateral skeletonized internal thoracic arteries (ITAs) in off-pump coronary artery bypass (OPCAB) retains several advantages that may eventually result in better patient outcomes. We compared the early results of OPCAB using bilateral ITAs as Y grafts with results of OPCAB using bilateral ITAs as in situ grafts. METHODS: A total of 223 consecutive patients who underwent OPCAB using bilateral skeletonized ITAs as Y grafts (group I, n = 113) or in situ grafts (group II, n = 110) were studied. RESULTS: Both the number of distal anastomoses per patient and the number of distal anastomoses per bilateral ITA were higher in group I (3.5 +/- 1.0 and 2.9 +/- 0.7) than in group II (3.0 +/- 0.7 and 2.4 +/- 0.5) (p < 0.01). Hospital mortality was 1.8% (2/113) in group I and 0.9% (1/110) in group II (p = ns). There were no differences in postoperative complications including atrial fibrillation (13.3% vs 10.9%), perioperative myocardial infarction (0.9% vs 2.7%), mediastinitis (0.9% vs 1.8%), and hypoperfusion syndrome (0.9% vs 0%) between groups I and II (p = ns). Postoperative coronary angiographies performed in 110 patients in group I and 108 patients in group II showed 99.0% (382/386) overall patency and 99.4% (319/321) patency for distal anastomoses using ITAs in group I, and 98.1% (312/318) overall patency and 98.1% (258/263) patency for distal anastomoses using ITA in group II. There were no significant differences in graft patency rates between the two groups (p = ns). CONCLUSIONS: Our results demonstrate that OPCAB using bilateral skeletonized ITAs is technically feasible, with excellent graft patency. Using bilateral skeletonized ITAs as Y grafts increases the number of distal anastomoses that can be performed and does not cause additional postoperative morbidity.
We present a technique that permits the grafting of two vessels with the left internal thoracic artery when a sequential graft cannot be performed. The left internal mammary artery is anastomosed to itself resulting in a loop that will be cut open at the time of the coronary anastomosis.
BACKGROUND: This study was conceived to evaluate the effect of internal thoracic artery (ITA) skeletonization on vessel wall integrity. METHODS: Forty consecutive patients undergoing coronary artery bypass were randomized to receive a skeletonized (n = 22) or a pedicled (n = 18) ITA graft. ITA harvesting was performed by 2 experienced surgeons using the same instrumentation and technique. Specimens were examined by light and electron microscope in order to assess vascular wall integrity. A specific immunohistochemical staining and a computerized method were used to quantify the degree of endothelial integrity after surgical preparation. RESULTS: Morphologic analysis revealed 2 cases of limited subadventitial hemorrhage (one for each group) and no case of major arterial damage. Immunohistochemical staining demonstrated an extremely high degree of maintenance of the endothelial integrity in both groups (97.2% +/- 1.9% in the skeletonized and 96.8% +/- 2.1% in the pedicled one; p = 0.53). CONCLUSIONS: Skeletonization does not affect ITA wall integrity in humans submitted to coronary artery bypass procedures.
OBJECTIVE: The left internal thoracic artery (LITA) is the most important graft for coronary artery bypass grafting (CABG). Its distal region is, however, prone to vasospasm. The effect of nitroglycerin (NTG) and isosorbide-dinitrate (ISDN) on different segments of this region was studied. METHODS: Rings of three segments of the LITA were studied: 6-9 mm proximal to the bifurcation (part A); 1-3 mm proximal to the bifurcation (part B); and 3-6 mm distal to the bifurcation (part C). After baseline, maximal contraction of the rings was achieved using 60 mmol/l of KCl, they were exposed to increasing doses of ISDN and NTG (10-100 microg/ml), and dose-response curves were recorded. RESULTS: The contractile response of part A to KCl was significantly lower than that of parts B and C (1.87+/-0.25 versus 4.05+/-0.39 and 7.64+/-0.54 g, respectively; P<0.001). Both nitrates inhibited the contractile response in a concentration-dependent manner. The relaxing effects of both nitrates on part A was most pronounced (P<0.01), with the effect of ISDN being higher than that of NTG (P<0.01). CONCLUSIONS: The region 6-9 mm proximal to the LITA bifurcation is less prone to vasospasm, and has greater relaxation responses to ISDN and NTG than the more vasospastic distal parts of the LITA. We recommend avoiding the use of the very distal part of this artery during CABG, and to use high doses of ISDN rather than NTG as an anti-spastic measure.
Because of excellent long-term patency (greater than 90% at 7 years), internal thoracic artery (ITA) bypass grafts are preferred over saphenous vein grafts for myocardial revascularization. ITA grafts can be used for up to 70% of all distal anastomoses and in up to 95% of patients. ITA grafts are more technically demanding; inadequate length, traumatic arterial injury, torsion, separation of intima and adventitia, and anastomotic stricture are important pitfalls. Postoperative problems of bleeding, phrenic nerve injury, mediastinal infection, and arm paresis or paresthesia are complications attributed to ITA grafts, but they are uncommon if meticulous technique is used.
The vasocontractile effect of 12-deoxyphorbol 13-isobutyrate (DPB), an activator of protein kinase C (PKC), was studied to clarify the mechanism of the vascontractile response elicited by activation of PKC. DPB induced both a sustained increase in intracellular Ca2+ levels and contraction in isolated rat thoracic artery. For a given increase in intracellular Ca2+ levels. DPB induced a greater contraction than high K+ or ionomycin. In Ca(2+)-free media, DPB induced concentration-dependent contraction with a slow rate of rise without causing detectable changes in intracellular Ca2+ levels. The DPB-induced contractions in Ca(2+)-free media were less inhibited by the inhibitors of calmodulin or myosin light chain kinase than ionomycin-induced contractions in normal media were. These results indicate that activation of PKC might increase the Ca2+ sensitivity of contractile elements due to mechanisms not associated with the Ca(2+)-calmodulin pathway.
During a routine dissection a superficial artery was observed coursing subcutaneously at the anterior border of the axillary base towards the thoracic wall and bilaterally at the lower border of the pectoralis major muscle. On the right side it originated from the 3rd part of the axillary artery but on the opposite side the origin was from the first centimetre of a left radial artery originating directly from the axillary artery together with the left brachial artery. Apart from the bilateral absence of the deep brachial artery, no other anomalies were identified at this level. This variant corresponds to the alar thoracic artery, an unusual and rarely reported artery. The literature on the subject contains no reference either to the bilateral evidence for the alar thoracic artery or to the possibility of an origin from a high radial artery. The presence of such an alar thoracic artery may interfere with surgical access within the axillary fossa and should be taken into consideration.
OBJECTIVE: Spasm remains a potential problem encountered during the use of arterial grafts in coronary artery bypass surgery. Heme oxygenase plays a role in the control of arterial vasoreactivity. Heme oxygenase exists in 2 constitutive isoforms (heme oxygenase 2 and 3) and an inducible isoform (heme oxygenase 1). The aim of our study was to induce heme oxygenase 1 by using hemin in human internal thoracic and radial arteries and to evaluate the effect of this induction on the contractility of these arterial grafts. METHODS: Segments of human arterial grafts obtained from patients undergoing isolated coronary artery bypass surgery were incubated in organ chambers for 4 hours in the presence of 10(-4) mol/L hemin. Concentration-response curves to norepinephrine were obtained in control and hemin-treated arterial rings. Heme oxygenase 1 expression was evaluated by using enzyme-linked immunosorbent assays and immunohistochemical staining. RESULTS: The contractility of the arterial rings to norepinephrine was significantly reduced after incubation with hemin. Zinc protoporphyrin (an inhibitor of heme oxygenase) reversed the effect of hemin, whereas the inhibitor of nitric oxide synthase had no effect. The inhibitor of soluble guanylate cyclase blocked the decrease in contractility induced by hemin. Immunohistochemical staining revealed a large expression of heme oxygenase 1 in all vascular layers of hemin-treated internal thoracic artery and radial artery rings. Enzyme-linked immunosorbent assay studies showed a significant increase in heme oxygenase 1 levels in hemin-treated internal thoracic artery and radial artery rings. CONCLUSION: Hemin caused in vitro induction of heme oxygenase 1 in human internal thoracic artery and radial artery grafts. This induction resulted in a reduced contractility to norepinephrine, partially through the cyclic guanosine monophosphate-dependent pathway. This effect was independent from nitric oxide synthesis.
BACKGROUND: We have previously shown the feasibility of assessing internal thoracic artery (ITA) size and blood flow hemodynamics before and after coronary artery bypass grafting using color-flow duplex ultrasound. This noninvasive method would be an ideal diagnostic tool for the evaluation of ITA graft status after therapeutic interventions in a patient with angina after coronary artery bypass grafting. The purpose of this study was to investigate the effects of nitroglycerin on the diameter and blood flow velocities of the left native ITA before coronary artery bypass grafting and the ITA graft postoperatively. METHODS: The study consisted of 24 male patients (mean age, 59 +/- 2.3 years) who had undergone elective coronary artery bypass grafting using a left ITA graft to the left anterior descending artery, with additional saphenous vein grafts. Color-flow duplex ultrasound (5.0-MHz transducer) was used for both the preoperative imaging of native ITAs and the postoperative study of ITA grafts before patient discharge. Repeated-measures analysis of variance was used to compare measurements of the ITA size and flow velocities (peak systolic velocity and end-diastolic velocity) at 5, 10, and 15 minutes after a single dose of sublingual nitroglycerin (0.4 mg) with the baseline values obtained without nitroglycerin. RESULTS: The preoperative native left ITA and the postoperative left ITA graft diameters responded to sublingual nitroglycerin by showing a rapid and significant increase beginning at 5 minutes and lasting up to 15 minutes (p = 0.0001). Sublingual nitroglycerin caused the peak systolic velocity of the native left ITA to be augmented at 5 minutes (p = 0.0002), and this effect was still apparent at 10 minutes (p = 0.0001) and 15 minutes (p = 0.0192). However, postoperative left ITA graft peak systolic velocities remained unaffected by the sublingual nitroglycerin (p = not significant). CONCLUSIONS: We conclude that instantaneous noninvasive measurement of ITA graft size and blood flow velocities after a therapeutic drug intervention may be clinically useful, particularly in a post-coronary artery bypass grafting patient with recurrent angina.
This study was conducted to compare the coronary flow distributed by single and bilateral internal thoracic artery (ITA) grafts in the setting of the left main coronary occlusion. Ten dogs underwent coronary artery bypass grafting through a left thoracotomy, off pump, using a brief local occlusion to perform the anastomosis. Dogs were randomly assigned to receive either a single left ITA (LITA) graft to the circumflex coronary artery (CFX), or bilateral ITA grafts, with additional placement of the right ITA (RITA) to the left anterior descending artery (LAD). After the grafts were placed, the left main coronary artery was ligated. Electromagnetic flows were obtained in the LAD and the CFX proximally and distally to ITA grafts in both groups before grafting and after grafting. ITA flow in situ was also measured before rotation from the chest wall. Total left ventricular flow requirements were satisfied equally well by either a single LITA graft (116.7 +/- 11.6 mL/min) or bilateral ITA grafts (total, 116.8 +/- 9.6 mL/min divided as LITA, 55.9 +/- 7.4 mL/min; RITA, 60.9 +/- 12.0 mL/min). When two grafts were replaced, competitive flow in the proximal regions of both native vessels was noted, although basal flow requirements were maintained. When an individual graft was occluded in the bilaterally grafted system, the remaining graft immediately recruited the additional flow, demonstrating that either right or left ITA can support flow demands five to six times higher than in situ chest wall flow (RITA, 21.9 +/- 3.1 mL/min; LITA, 22.3 +/- 4.9 mL/min). These data suggest that in this canine model, a single ITA graft can support the entire flow requirements of the left ventricle. Assuming no intervening stenosis is present in native coronary systems, bilateral ITA grafting may provide a margin of safety, but under resting conditions, provides no perfusion advantages over a single ITA graft.
Vasodilation that occurs during normal pregnancy is associated with enhanced relaxation and decreased contractile response to agonists, which are in part due to increased stimulated and basal nitric oxide (NO). In preeclampsia and/or pregnancies carried at high altitude (HA), this normal vascular adjustment is reversed or diminished. We previously reported that HA exposure did not inhibit the pregnancy-associated decrease in contractile response to agonist or basal NO in guinea pig uterine arteries (UA). We therefore sought to determine whether altitude interfered with effects of pregnancy on endothelium-dependent relaxation through a reduction in stimulated NO. We examined the relaxation response to ACh in UA and bradykinin in thoracic arteries (TA) and effects of NO inhibition with 200 microM N(G)-nitro-L-arginine (L-NNA) in arterial rings isolated from nonpregnant and pregnant guinea pigs exposed throughout gestation to low altitude (LA, 1,600 m, n = 26) or HA (3,962 m, n = 22). In pregnant UA, relaxation to ACh was enhanced (P < 0.05) at both altitudes and NO inhibition diminished, but did not reverse, ACh relaxation. The effect of L-NNA on the relaxation response to ACh was less in HA than in LA animals (P = 0.0021). In nonpregnant UA, relaxation to ACh was similar in LA and HA animals. L-NNA reversed the relaxation response to ACh at HA but not at LA. In TA, relaxation to bradykinin was unaltered by pregnancy or altitude and was completely reversed by NO inhibition. These data suggest that effects of NO inhibition are diminished in UA during pregnancy at HA. Additional studies are needed to confirm whether these effects are mediated through inhibition of stimulated NO. HA exposure did not inhibit relaxation to ACh, perhaps because of stimulation of other vasodilators.
The interaction between primary afferent neurons containing neuropeptides and the vascular smooth muscle is incompletely understood. To explore the function of perivascular afferent neurons and to determine whether they produce local effects on vascular smooth muscle cells, we investigated the effects of acute capsaicin and substance P administration in vitro on human internal thoracic arteries (ITA). Vessels were obtained from patients undergoing coronary bypass or from multiorgan transplant donors. Fourteen ITA segments (5 mm wide) were suspended as rings between two stainless-steel stirrups in water-jacketed (37 degrees C) tissue baths under 2.5 to 3 g of basal tension. The tissue baths contained 10 mL physiological salt solution (PSS) of the following composition (mM): NaCl, 119; KCl, 4.7; NaH2PO4, 1.0; MgCl2, 0.5; CaCl2, 2.5; NaHCO3, 25; and glucose, 11; aerated continuously with 95% O2 and 5% CO2. Peptidase inhibitors (phosphoramidon and captopril) were added to PSS to decrease peptide degradation. Mechanical responses were measured isometrically and recorded on a polygraph via isotonic force transducers. Vessels were preconstricted with submaximal concentrations of norepinephrine. After the tension had stabilized, substance P or capsaicin was added cumulatively to the tissue bath. At the end of the experiments, the viability of ITA was verified by its responses to endothelial-dependent (acetylcholine) and endothelial-independent (sodium nitroprusside) vasodilators. In the endothelium-intact ITA segments, substance P produced relaxation of ITA smooth muscle while it induced slight contraction when the ITA was devoid of its endothelium (P = 0.0585). The addition of capsaicin to human ITA primarily produced contractile effects on the developed smooth muscle force. The capsaicin-induced contraction of the ITA smooth muscle was independent of endothelial cell integrity, although contraction was greater in the endothelium-intact ITA segments (P = 0.0165). The acute capsaicin exposure of human ITA revealed that primary afferent neurons containing neuropeptides innervate human ITAs. There is a real potential for perivascular afferent neurons and sensory peptides to influence the ITA smooth muscle function.
The scores based on Doppler sonographic spectral features in 14 vertebral arteries with flow reversal and 10 vertebral arteries with normal antegrade flow were correlated with those of ipsilateral internal thoracic (or internal mammary) and subclavian arteries. The statistical analysis revealed significant correlation between the scores of all ipsilateral arteries. We concluded that color duplex ultrasonographic examination of internal thoracic arteries should be carried out in all patients with flow reversal in vertebral arteries. It is especially important in those who are potential candidates for coronary revascularization using in situ internal thoracic artery graft.
We describe the wrapping of the proximal segment of the left internal thoracic artery graft in a polytetrafluoroethylene membrane. Two groups of patients were compared (99 patients with wrapping, 70 patients as controls). There were no statistical differences between the two groups regarding the postoperative course. Three patients in the polytetrafluoroethylene group and 2 in the control group underwent reoperation for valve surgery. Exposure of the wrapped graft segment for clamping was safer and more rapid than in the control group.