A technique for salvaging a critical internal mammary artery bypass graft damaged during resternotomy

Resternotomy in the presence of a patent internal mammary artery graft poses an addition hazard to the reoperation. We describe a situation in which the patent mammary artery graft to the left anterior descending artery was severed and retracted during sternal reentry for an aortic valve replacement. We illustrate a simple technique for restoring the blood supply using a coronary artery shunt.     

Endothelial cell-seeded bovine internal mammary artery for complete revascularization

We present a 79-year-old woman with coronary heart disease who underwent complete revascularization by using a No-React bovine internal mammary artery seeded with autologous endothelial cells. Her postoperative course was uneventful, and the patient was recently in New York Heart Association functional class I. Multislice computed tomography imaging showed patent grafts at 20 months of follow-up.     

Papaverine delivery to the internal mammary artery pedicle effectively treats spasm

Background

Left internal mammary artery spasm is well recognized during coronary artery bypass operations. Papaverine has been used by many surgeons to maximize mammary artery flow perioperatively, but the best delivery method is not known. We analyzed two techniques used at our institution.

Methods

Fifty-eight patients were randomized into three groups to compare papaverine's ability to prevent spasm and to treat established spasm. Group 1 was control and no treatment was employed. In group 2, papaverine was injected with a blunt needle through the endothoracic fascia parallel to the mammary artery before harvest to assess spasm prevention. In group 3, papaverine was delivered perivascular in an identical manner to group 2 but after the mammary artery was dissected from the chest wall. This group was an evaluation of spasm treatment. Drug dosage was the same for both groups and routine bypass grafting was performed. Before anastomosing the mammary artery to the left anterior descending artery, blood flow was recorded for 15 seconds and flow per minute calculated. Cardiopulmonary bypass pressures were maintained at 70 mm Hg during collection.

Results

Mean blood flows were: group 1 = 86.2 mL/min, group 2 = 122.5 mL/min, and group 3 = 139.7 mL/min. Left internal mammary artery flow in group 3 was statistically different from control (p = 0.0457). Group 2 flow approached but did not reach statistical significance (p = 0.0874). Mammary artery dissection times for the three groups were not different.

Conclusions

Papaverine delivery to the left internal mammary artery after dissection treats spasm effectively, improves blood flow at the time of its anastamosis to the left anterior descending artery, and avoids any risk of intimal injury. Injection of papaverine before mammary artery harvest does not shorten dissection time, and flow is not statistically improved.     

Long-term left internal mammary artery graft patency for coronary artery disease associated with pseudoxanthoma elasticum

Pseudoxanthoma elasticum (PXE) is a rare, inherited connective tissue disorder with numerous systemic manifestations that include premature coronary artery disease. Coronary artery bypass grafting (CABG) is known to be beneficial in patients with PXE-related coronary artery disease. In these patients, however, the suitability of arterial conduits, including the internal mammary artery, has been controversial. We present a patient with PXE-related coronary artery disease who has had long-term patency of a left internal mammary artery (LIMA) graft after an off-pump CABG procedure in which LIMA and bilateral radial artery conduits were used.     

Off-pump long onlay bypass grafting using left internal mammary artery for diffusely diseased coronary artery

Surgical treatment of a diffusely diseased coronary artery has been considered a relative contraindication for off-pump coronary artery bypass grafting. To our knowledge, long onlay-patch grafting with off-pump coronary artery bypass grafting has not been described. Two sets of Octopus 3 tissue stabilizers were placed longitudinally along the target coronary artery. This allowed us to perform surgical angioplasty and bypass grafting without cardiopulmonary bypass support (double Octopus technique). We report our early experience with off-pump long onlay bypass grafting in patients with a diffusely diseased coronary artery using double Octopus tissue stabilizers.Diffusely diseased coronary artery; off-pump coronary artery bypass grafting; coronary artery reconstruction; coronary artery bypass grafting; onlay patch anastomosis     

Phrenic nerve injury associated with high free right internal mammary artery harvesting

BACKGROUND: The right phrenic nerve is at risk of injury during high mobilization of the right internal mammary artery (RIMA). The incidence and implications of this injury have not been previously defined. METHODS: Prospectively collected data on all patients who underwent RIMA harvesting between January 1995 and February 2002 were analyzed. Thirty-one patients with right phrenic nerve injury were identified and the medical charts reviewed. Phrenic nerve injury was diagnosed when a postoperative chest roentgenogram showed the right hemidiaphragm to be two or more intercostal spaces higher than the left, or transection of the nerve was seen intraoperatively. Investigations included fluoroscopy and spirometry in upright and supine positions. Diaphragm plication was offered for symptom control. Subsequent follow-up was undertaken to determine the incidence of spontaneous recovery of diaphragm function and the benefits of diaphragm plication. RESULTS: Seven hundred and eighty-three patients underwent high mobilization of the RIMA with proximal detachment for use as a free graft. Thirty-one patients with right hemidiaphragm dysfunction were identified in the postoperative period providing an injury incidence of 4% (confidence interval, 2.6% to 5.3%). Of these, 12 patients underwent diaphragm plication (4 early and 8 late), 14 patients achieved spontaneous recovery, and 5 patients were lost to follow-up. The supine to upright forced vital capacity ratios at the time of phrenic nerve dysfunction, after diaphragm plication, and after spontaneous recovery were 0.79, 0.90, and 0.96 respectively. CONCLUSIONS: The incidence of phrenic nerve injury associated with high RIMA harvesting was 4% but spontaneous recovery may be anticipated in two thirds (14 of 22) of patients in whom the injury is identified postoperatively. High RIMA harvesting should be used with caution in patients with preoperative pulmonary dysfunction in whom phrenic nerve injury would be poorly tolerated.     

Extending the in situ right internal mammary artery graft with retrocaval positioning

Bilateral internal mammary artery grafting is associated with improved long-term patient outcomes. In situ right internal mammary artery grafting of the obtuse marginal artery, through the transverse sinus, is often limited by conduit length. We describe the technique of retrocaval positioning of the right internal mammary artery graft to extend its functional length for grafting of the circumflex territory. With careful surgical technique, this procedure can be performed safely during routine coronary bypass operations.     

Interaction between vasodilators and vasopressin in internal mammary artery and clinical significance

BACKGROUND: Arginine vasopressin (AVP) has recently been demonstrated as an alternative in the treatment of severe refractory vasodilatation in coronary artery bypass grafting. However, AVP may be a spasmogen for graft spasm. We compared the in vitro antispastic effect among calcium-channel antagonists (nifedipine, diltiazem, and verapamil), nitroglycerin, and the highly selective AVP (V1) receptor antagonist [1-deaminopenicillamine, 4-valine, 8-D-arginine] vasopressin. METHODS: Human internal mammary artery segments (n = 218) were studied in organ baths. The inhibitory effects of the above vasodilators on AVP-mediated contraction were studied in two ways: relaxation with AVP precontraction and depression of the AVP-induced contraction after pretreatment with vasodilators. RESULTS: All three calcium-channel antagonists caused limited relaxation (18.3%+/-5.4% for nifedipine, n = 11; 22.2%+/-3.8% for verapamil, n = 10; and 26.2%+/-7.5% for diltiazem, n = 9). The plasma concentration of calcium-channel antagonists had no significant depression effect on the AVP-induced contraction. In contrast, [1-deaminopenicillamine, 4-valine, 8-D-arginine] vasopressin caused full (100%, n = 11) and nitroglycerin caused nearly full (93%+/-3%, n = 10) relaxation. Pretreatment with [1-deaminopenicillamine, 4-valine, 8-D-arginine] vasopressin (10(-8), 10(-7), or 10(-6) mol/L, respectively) significantly increased the effective concentration for 50% of the AVP-induced contraction (10(-8.6)+/-10(0.1) mol/L, p = 0.009; 10(-7.8)+/-10(0.07) mol/L, p = 0.000; or 10(-6.9)+/-10(0.11) mol/L, p = 0.000 versus the control, 10(-9.24)+/-10(0.16) mol/L). However, nitroglycerin only slightly depressed the AVP-induced contraction. CONCLUSIONS: [1-Deaminopenicillamine, 4-valine, 8-D-arginine] vasopressin may provide specific antispastic effect in either prophylaxis or treatment of the AVP-related vasospasm in the internal mammary artery. Nitroglycerin may be effective in treatment but has little effect on prophylaxis. Use of calcium-channel antagonists may have little benefit in AVP-related vasospasm.     

Ventricular fibrillation with diminished internal mammary artery graft flow during sternal retraction

Ventricular fibrillation is a common arrhythmia encountered after the termination of cardiopulmonary bypass. Risk is augmented in patients who are undergoing repeat cardiac procedures with most documented complications occurring during repeat sternotomy. Aortic valve surgery is more complex after coronary artery bypass grafting using internal mammary arteries, and it compounds the increased risk of repeat sternotomy. This case report describes a low-flow state artificially created by sternal retraction applying tension on a right internal mammary artery to posterior descending artery anastomosis, with resultant unrecognized myocardial ischemia yielding refractory ventricular fibrillation during aortic valve replacement.     

Nitric oxide and prostacyclin in ultrasonic vasodilatation of the canine internal mammary artery

BACKGROUND: Investigators recently demonstrated increased free blood flow from radial artery free grafts harvested using ultrasonic technology. We investigated the mechanism underlying this phenomenon. METHODS: Canine internal mammary artery segments (with and without intact endothelium) were precontracted with norepinephrine and sonicated 3 seconds in organ chambers with ultrasonic coagulating shears (Harmonic Scalpel; Ethicon Endo-Surgery, Cincinnati, OH) functioning at level 2. Vessel tension was continuously measured to examine vasoactivity in response to sonication alone (control) or with N(ù)-Nitro-l-arginine (l-NNA) and indomethacin added to the chamber medium individually or in combination. Tissue heating, acoustic pressure, and endothelial damage as detected by scanning electron micrography were also assessed. RESULTS: In vitro sonication with the Harmonic Scalpel induced predominately endothelium-dependent internal mammary artery vasorelaxation but a small endothelium-independent contribution was also observed. Early vasorelaxation (1 minute after stimulus) was maximally inhibited by l-NNA alone and in combination with indomethacin. Relaxation during this period was insignificantly affected by indomethacin alone. Only the combination of l-NNA and indomethacin maximally inhibited late vasorelaxation (5 minutes after stimulus), whereas inhibitory effects of l-NNA diminished during this time period. Indomethacin inhibited relaxation substantially during this phase, although significantly less than did l-NNA alone. The Harmonic Scalpel minimally heated the tissue surface (0.3 +/- 0.03 degrees C) and did not disrupt endothelial cell integrity while operating at 50 mW/cm(2) intensity (acoustic pressure 40 kPa). CONCLUSIONS: Sonication induces vasorelaxation almost completely by time-dependent endothelial nitric oxide and prostacyclin release, which appears unrelated to tissue heating or endothelial architectural disruption.     

Technique of lung retraction during internal mammary artery harvesting

We describe a novel technique for lung retraction during dissection of the internal mammary artery for its use in coronary artery bypass grafting. The lung is retracted using the blades of the Octopus (Medtronic Inc, Minneapolis, MN) suction stabilizer, without the suction connected. This technique can be used when the internal mammary artery is harvested by widely opening the pleura or by the extrapleural approach. This technique makes mammary artery dissection easy, and it can be used for harvesting internal mammary arteries bilaterally. The method described is simple, causes no impairment in gas exchange, and offers no additional expense, because the same stabilizer would be used later for the off-pump coronary artery bypass surgery.