Long-term fate of the internal mammary artery and saphenous vein grafts

Comparing Outcomes in Patients Undergoing Coronary Artery Bypass Grafting With and Without Using the Internal Mammary Artery in a Tertiary Care Hospital

Purpose

The left internal mammary artery in coronary artery bypass grafting (CABG) is considered to be an important intraoperative quality indicator with excellent long-term results. The purpose of this study is to compare the early outcomes of CABG with and without the left internal mammary artery (LIMA) in the South Asian population and to look for the utilization of LIMA as per the recommendations of the Society of Thoracic Surgeons in a developing country.

Materials and methods

A retrospective review was carried out for all patients who underwent CABG from 2010 to 2015. Patients were divided into two groups on the basis of whether LIMA was used (Group I) or not used (Group II) as a conduit. Both groups were further subdivided into elective and urgent. Preoperative, intraoperative, and postoperative variables were recorded and compared.

Results

After exclusion, a total of 2619 patients underwent isolated CABG surgery during the required duration. The LIMA was used in 94% of the patients (n=2472) while 147 patients underwent CABG without LIMA. The use of LIMA was associated with significantly lower mortality (2% LIMA vs 8.8% no LIMA), as well as a decrease in major comorbidity, stroke, and prolonged ventilation. In the subgroup analysis, LIMA usage in elective and urgent cases was associated with significantly lower mortality (elective 1.6% LIMA vs 7.4% No LIMA) (urgent 4.8% LIMA vs 15.7 % no LIMA)) and major morbidity.

Conclusion

The outcomes of CABG procedures without LIMA were not encouraging. Our results support compliance with standard adult cardiac surgery quality-of-care guidelines.

Natural History of Moderate Coronary Artery Stenosis After Surgical Revascularization

BACKGROUND

It remains controversial whether grafting moderately stenosed coronary arteries (MSCAs) influences native-vessel disease progression and whether grafting may protect against late myocardial ischemia.

METHODS

From 1972 to 2011, 55,567 patients underwent primary isolated coronary artery bypass grafting (CABG); 1,902 had a single coronary artery with angiographically moderate (50% to 69%) stenosis and ≥1 postoperative angiogram. Disease progression was studied in 489 nongrafted, 371 internal thoracic artery (ITA)-grafted, and 957 saphenous vein (SV)-grafted MSCAs, as well as patency of 376 ITA and 1,016 SV grafts to these MSCAs.

RESULTS

At 1, 5, 10, and 15 years, native-vessel disease progressed from moderate to severe stenosis/occlusion in 32%, 52%, 66%, and 72% of nongrafted MSCAs; 55%, 73%, 84%, and 87% of ITA-grafted MSCAs; and 67%, 82%, 90%, and 92% of SV-grafted MSCAs. After adjusting for patient characteristics, MSCA disease progressed 3.6 times faster with ITA and 10 times faster with SV grafting compared with nongrafting. At these same time points, occlusion of ITA grafts to MSCAs was 8%, 9%, 11%, and 15% and for SV grafts, 13%, 32%, 46%, and 56%; protection from myocardial ischemia by ITA-grafted versus nongrafted MSCAs was 29%, 47%, 59%, and 61%.

CONCLUSIONS

Most MSCAs progress to severe stenosis or occlusion in the long term. Progression is faster in grafted than nongrafted MSCAs, more so with SV than ITA grafts. However, ITA grafts to such arteries have excellent patency, providing long-term protection from myocardial ischemia. Therefore, ITA grafting of MSCAs should be considered.

Endothoracic Papaverine Application for Internal Thoracic Artery Harvest

This study compared the effects of different methods of papaverine application on free blood flow and harvesting time of the internal thoracic artery for coronary bypass grafting. Patients were randomly divided into 3 groups of 25 each: group 1 had papaverine injected into the endothoracic tissue around the internal thoracic artery before dissection, group 2 had papaverine injected into the periarterial tissues of the internal thoracic artery pedicle, and group 3 had intraluminal papaverine applied retrogradely into the internal thoracic artery. Mean blood flow was 56.3 ± 21.3, 21.1 ± 13.2, and 20.9 ± 9.1 mL · min−1 in groups 1, 2, and 3, respectively, immediately after harvesting. Flow in group 1 was significantly better than that in groups 2 and 3. Immediately before anastomosis, mean flow was 89.8 ± 19.1, 97.6 ± 35.4, and 95.9 ± 19.9 mL · min−1 in groups 1, 2, and 3, respectively, with no significant difference among groups. Internal thoracic artery harvesting times were shorter in group 1 than in groups 2 and 3. Administering papaverine into the endothoracic fascia of the internal thoracic artery bed prior to dissection is a reliable method that facilitates rapid harvesting of the graft without causing trauma and consequent spasm.

Comparison of the radial artery and saphenous vein as composite grafts in off-pump coronary artery bypass grafting in elderly patients: a randomized controlled trial

Background and Objectives

Arterial grafts have a better long-term patency rate than saphenous vein (SV) when used in off-pump coronary artery bypass surgery (OPCAB). However, arterial grafts in elderly patients are often diseased. We sought to compare the early outcomes achieved by using the two different types of composite grafts.

Subjects and Methods

We conducted a randomized trial to compare radial artery (RA) and SV composite grafts based on the in situ left internal mammary artery in 60 elderly (>70 years old) patients, who were scheduled to undergo OPCAB. Clinical outcomes and 1-year postoperative CT angiography results were compared. The quality of the conduit was evaluated by employing vascular ultrasonography, optical coherence tomography (OCT), and histologic examination.

Results

No differences in immediate postoperative morbidity and mortality were observed between the two groups. Early postoperative CT angiography revealed a SV patency rate of 100%, which was not different from that of RA composite grafts (99.1%). CT angiography after a year showed an overall patency rate of 96.3%. The overall patency rate of the SV group at 1 year was 94.7%, which was similar to that of the RA group (97.4%). Also, there was no difference in overall survival rate between the two groups. Vascular ultrasonographic images showed strong correlations between OCT and histopathology.

Conclusion

Our analysis of early outcomes revealed that the SV could be used as an alternative composite graft to the RA in elderly patients. Vascular ultrasonography is an accurate, real-time, and reproducible method for assessing the quality of the RA conduit.

What has happened to multiple arterial grafting in coronary artery bypass grafting surgery?

Coronary artery bypass grafting (CABG) is a well-established therapy for patients with multivessel coronary artery disease, with excellent short- and medium-term results. This is best illustrated by studies comparing percutaneous coronary interventions (PCIs) with CABG surgery, where CABG continues to offer better event-free survival. However, there has been increasing concern about the long-term patency of vein grafts utilized for CABG when compared with arterial grafts. Some have suggested that revascularization with arterial grafts rather than vein grafts may result in improved outcomes following CABG. This is particularly important when one considers that graft occlusion can result in recurrence of disabling angina, rehospitalization, reintervention and death. To date, however, multiple arterial grafts have yet to become the standard approach for patients undergoing CABG. This is best exemplified by reports from large registries suggesting that the use of multiple arterial grafting is limited to approximately 10% of all patients undergoing CABG. In this article, we will provide some of the evidence outlining the risk and benefits of multiple arterial grafting, but more importantly, begin to explore why the utilization of multiple arterial grafting does not appear to be increasing significantly.

Serial quantitative coronary analyses for the evaluation of one-year change in saphenous vein grafts

BACKGROUND

A paucity of data exists with respect to changes in whole saphenous vein grafts (SVGs) despite accelerated atherosclerosis within grafted saphenous vein conduits. In the present study, we evaluated the one-year change in SVGs by means of quantitative coronary analysis.

METHODS

This study enrolled consecutive 52 patients with 109 SVGs, who underwent coronary artery bypass graft surgery successfully. A follow-up study was performed in 33 patients with 65 SVGs after one year because 16 SVGs were obstructed (baseline, 8; follow-up period, 8), and 15 patients with 28 SVGs dropped out within one year.

RESULTS

Both minimal and mean lumen diameters decreased significantly (3.17 +/- 0.64 mm vs 2.41 +/- 0.57 mm, p < 0.001; 3.70 +/- 0.69 mm vs 2.92 +/- 0.70 mm, p < 0.001; respectively). Graft length also decreased significantly (107.1 +/- 25.8 vs 100.6 +/- 25.2 mm, p < 0.001). The graft shortening rate (graft shortening length/baseline graft length x 100) was greater than 5% in 33 vessels (51%) and greater than 10% in 23 vessels (35%). Coronary risk factors (smoking, diabetes mellitus, hypertension, dyslipidemia) did not reveal significant relationship with late loss of minimal and mean lumen diameters.

CONCLUSIONS

The present study showed a considerable and uniform lumen loss of SVGs after one year, irrespective of coronary risk factors. Graft length shortening was seen more than elongation.

The effect of total arterial grafting on medium-term outcomes following coronary artery bypass grafting

BACKGROUND

While it is believed that total arterial grafting (TAG) for coronary artery bypass grafting (CABG) confers improved long-term outcomes when compared to conventional grafting with left internal mammary artery and saphenous vein grafts (LIMA+SVG), to date, this has not become the standard of care. In this study, we assessed the impact of TAG on medium-term outcomes after CABG.

METHODS

Peri-operative data was prospectively collected on consecutive first-time, isolated CABG patients between 1995 and 2005. Patients were divided into two groups based on grafting strategy: TAG (all arterial grafts no saphenous veins) or LIMA+SVG. Patients who had an emergent status or underwent fewer than two distal bypasses were excluded. Medium term univariate and risk-adjusted comparisons between TAG and LIMA+SVG cases were performed.

RESULTS

A total of 4696 CABG patients were included with 1019 patients undergoing TAG (22%). Unadjusted in-hospital mortality was 1.5% for TAG patients compared to 2.0% for LIMA+SVG (p = 0.31). The mean follow-up was 4.8 +/- 2.0 years for TAG patients compared to 6.1 +/- 3.0 years for LIMA+SVG patients (p < 0.0001). At follow-up total mortality (8% vs 19%; p < 0.0001), and the incidence of readmission to hospital for cardiac reasons (29% vs 38%; p < 0.0001) were significantly lower in TAG compared to LIMA+SVG patients. However, after adjusting for clinical covariates, TAG did not emerge as a significant independent predictor of long-term mortality (HR 0.92; CI 0.71-1.18), readmission to hospital (HR 1.02; CI 0.89-1.18) or the composite outcome of mortality and readmission (HR 1.00; CI 0.88-1.15). Risk adjusted survival was better than 88% in both TAG and LIMA-SVG patients at 5 years follow-up.

CONCLUSION

Patients undergoing TAG appear to experience lower rates of medium-term all-cause mortality and readmission to hospital for any cardiac cause when compared to patients undergoing LIMA+SVG. However, after adjusting for clinical variables, this difference no longer persists suggesting that at median follow-up there are no mortality or morbidity benefit based on the choice of conduit.

Atherosclerosis of Radial and Internal Thoracic Arteries Used in Coronary Bypass: Atherosclerosis in Arterial Grafts

BACKGROUND

This study aimed to evaluate the degree and incidence of atherosclerosis in internal thoracic (ITA) and radial arteries (RA) harvested for coronary bypass grafting.

MATERIALS AND METHODS

The association of major clinical events and etiological factors for atherosclerosis was investigated in 770 arterial segments obtained prospectively from 480 patients. Potential risk factors for atherosclerosis were age, gender, smoking, diabetes mellitus, peripheral vascular disease, cerebrovascular disease, chronic renal failure, hypercholesterolemia, obesity, hypertension, and a positive family history.

RESULTS

Six types of histological lesions have been defined; grade III or more was present in the RA in 47 (16%) patients and in the ITA in 30 (7%). The mean grade was 1.6 +/- 0.6 in the ITA and 2.1 +/- 0.9 in the RA (p < 0.001).

CONCLUSION

RA had a significantly greater prevalence of atherosclerosis than the same patients' ITA. There was a strong correlation between ITA atherosclerosis and age. The presence of calcification may lead surgeons to avoid an extra incision according to risk factors, although most of these are not predictive.

The contracting and relaxing responses of human internal mammary artery grafts harvested by two different methods

Perioperative spasm of internal mammary artery is a common experience in coronary artery bypass grafting. Many techniques were described of harvesting the internal mammary artery to prevent vasospasm. We investigated the comparison of the contracting and relaxing responses of human internal mammary artery grafts harvested by two different methods. Patients were divided into two groups depending on the harvesting technique. In the first and second groups arteries were harvested by classical and carbon dioxide insufflation techniques, respectively. In both groups, endothelial function of arteries was assessed by precontracting the rings with phenylephrine (10(-5)M) and dilatating them by cumulative acetylcholine (10(-8) to 10(-5)M) concentrations. Cumulative concentration-response curves for phenylephrine (10(-8) to 10(-4)M), noradrenaline (10(-9) to 10(-4)M), and 5-hydroxytryptamine (10(-9) to 10(-4)M) were obtained in all groups. Endothelial integrity of arteries were histopathologically evaluated. In both groups, acetylcholine caused concentration-dependent relaxations in rings precontracted with phenylephrine (10(-5)M). In arteries harvested by carbon dioxide insufflation technique, acetylcholine caused significantly higher relaxations compared to the rings obtained by classical technique (p<0.05). In all rings of study groups, phenylephrine, noradrenaline and 5-hydroxytryptamine caused concentration-dependent contractions. There was not any significant difference in concentration-dependent responses of these contracting pharmacological agents between the groups. Histopathological evaluation revealed no major arterial damage in both groups. Carbon dioxide insufflation technique does seem not only to protect the integrity of the endothelium and the whole vessel, but also prevent the possible vasospasm of the internal mammary artery segments.

Does competitive flow reduce internal thoracic artery graft patency?

BACKGROUND

In coronary arteries with moderate stenosis, competitive flow may lead to internal thoracic artery (ITA) graft occlusion. The goals of this study were to determine if competitive flow reduces ITA patency, and if there is a degree of coronary stenosis below which ITAs should not be used.

METHODS

From 1972 to 1999, 50,278 patients underwent primary coronary artery bypass grafting (CABG). Of these, 2,002 had at least one ITA graft and postoperative angiography before coronary reintervention; 2,999 angiograms of 2,121 ITAs were made. Time-related ITA occlusion was modeled using longitudinal analysis to identify its risk factors while accounting for lack of independence introduced by repeated angiography and multiple ITA anastomoses per patient. Proximal coronary stenosis (maximum preoperative stenosis between ITA anastomosis and aorta) was the surrogate for competitive flow.

RESULTS

Unadjusted ITA patency was 93%, 89%, 90%, and 92% at 1, 5, 10, and 15 years after CABG. Risk factors associated with ITA occlusion were lesser degree of proximal coronary stenosis (p < 0.0001); longer time from CABG in grafts to non-left anterior descending coronary arteries (p < 0.0001); female sex (p = 0.0003); later date of CABG (p = 0.01); right ITA (p < 0.0001); and smoking (p < 0.0001). In all arteries, as preoperative proximal coronary stenosis decreased, ITA patency declined; however, at no degree of stenosis was there a sharp decline.

CONCLUSIONS

Internal thoracic artery patency decreases as coronary competitive flow increases. However, the nature of this relationship indicates ITAs should not be abandoned at moderate grades of stenosis.

Early clinical and angiographic outcome of the pedicled right internal thoracic artery graft to the left anterior descending artery

BACKGROUND

The left internal thoracic artery (LITA) graft to the left anterior descending (LAD) artery became the gold standard graft in coronary surgery. Subsequently, the right internal thoracic artery (RITA) graft was increasingly used. However, there is still some debate about the optimal way of using this conduit. The aim of the present study was to assess our experience in grafting the pedicled RITA graft to LAD in 212 consecutive patients.

METHODS

The records of 212 consecutive patients who underwent isolated coronary artery bypass grafting with the pedicled RITA graft to the LAD artery at Harefield Hospital between January 1998 and May 2001 were retrospectively reviewed. We approached the last 35 consecutive patients to obtain an angiographic control group. All 35 patients (16.5%) consented and, before discharge, underwent angiography to look at the quality of anastomoses and the patency of grafts.

RESULTS

Successful catheterization and engagement of the RITA grafts was performed in 32 patients. Angiography showed that 32/32 (100%) of the RITA grafts were widely patent with excellent flow. The distal anastomoses of these RITA grafts were also satisfactory. There were no deaths among the study patients.

CONCLUSIONS

Our results show that the use of the pedicled RITA graft to the LAD artery provides a good early clinical and angiographic outcome, and suggests that the pedicled RITA graft to the LAD artery is a good alternative to the pedicled LITA graft to the LAD artery.

99mTc-MDP bone SPECT for the evaluation of sternal ischaemia following internal mammary artery dissection

Coronary artery bypass grafting (CABG) is one of the most frequently performed operations in the United States. The use of internal mammary artery (IMA) grafting has been identified as increasing the risk of sternal wound infections and mediastinitis. The purpose of our study was to prospectively evaluate the effect of different techniques of left internal mammary artery (LIMA) harvesting on sternal vascularity. Thirty-three patients undergoing primary coronary artery bypass grafting were studied. The patients were divided into groups that received a skeletonized IMA (group I, n=11), a pedicled IMA (group II, n=12), or a semiskeletonized IMA (group III, n=10) graft. Each patient underwent a preoperative 99mTc-methylene diphosphonate bone scan using single photon emission computed tomography (SPECT). The ratio of the mean counts/pixel for each side of the sternum was obtained. Post-operatively, all patients had a repeat bone SPECT. Ratios of unilateral sternal uptakes were compared to the preoperative study. A univariable analysis of post-operative to pre-operative ratios revealed statistically significant reduction in vascularity to the left side of the sternum post-operatively in group II compared with groups I and III (0.68 0.12 vs 0.99 0.24 and 0.93 0.09; P<0.01). There was no difference between groups I and III (P=1). Multivariable analysis revealed only the type of harvesting to be associated with post-operative reduction in left to right sternal activity ratio (P<0.02). Pairwise comparisons revealed that differences are due to pedicled type of harvesting (group II vs group I, P=0.03; II vs III, P=0.001; and I vs III, P=0.115). A pedicled IMA graft causes acute post-operative sternal ischaemia. This does not occur when the IMA is skeletonized or semiskeletonized. Hence, it may be prudent to minimize dissection during mobilization of the IMA to decrease the likelihood of post-operative sternal complications.

Arterial balloon catheter: a new atraumatic device for dilating arterial grafts

BACKGROUND

Harvesting of the internal mammary artery (IMA) for use in myocardial revascularization may result in spasm, which can impair early graft flow. Hydrostatic and mechanical dilatation can exert an intraluminal shear force, causing denudation of the IMA endothelium. A new long balloon dilatation technique (LB) has been developed to mechanically increase IMA diameter and flow without exerting any shear force on the endothelium.

METHODS

Vascular rings of porcine IMA were divided into four groups: no manipulation (control), metal dilators (MD), short balloon (SB), or LB intraluminal dilation. In situ flows after dilation and percentage of intact endothelium after silver nitrate staining were determined. Endothelium-dependent contractions with arachidonic acid, relaxations with acetylcholine, endothelium-independent contractions with norepinephrine, and relaxation with sodium nitroprusside were recorded in organ chamber experiments.

RESULTS

Increases in IMA flows were similar in all dilated groups. Endothelium-independent contractions and relaxations of IMA smooth muscle were unaffected by any type of mechanical dilation. However, endothelium-dependent contractions and relaxations were significantly impaired after MD and SB but preserved after LB dilation compared with control. Silver nitrate staining showed a greater preservation of the endothelial coverage after LB dilation.

CONCLUSIONS

IMA dilatation with the novel arterial LB catheter increases IMA flow and preserves endothelial cell integrity, making it an effective and atraumatic method to relieve IMA spasm before use for coronary artery bypass grafting.

The effects of fenoldopam on coronary conduit blood flow after coronary artery bypass graft surgery

OBJECTIVE

To quantify the effects of fenoldopam, 0.1 microg/kg/min, on left internal mammary artery (LIMA) and saphenous vein blood flow after coronary anastomosis.

DESIGN

Prospective, randomized, double-blind, placebo-controlled trial.

SETTING

University teaching hospital, single institution.

PARTICIPANTS

Thirty-one American Society of Anesthesiologists III patients undergoing elective coronary revascularization.

INTERVENTIONS

A perivascular ultrasonic flow probe (Linton Instrumentation, Norfolk, UK) was placed around the LIMA and saphenous vein graft after coronary anastomosis.

MEASUREMENTS AND MAIN RESULTS

Immediately before and at 5-minute intervals for 15 minutes after starting the infusion, blood flow was measured in the LIMA and one saphenous vein graft using a transit time ultrasonic flow probe. Heart rate, blood pressure, and central venous pressure were documented at these time points. Administration of fenoldopam, 0.1 microg/kg/min, did not alter heart rate or blood pressure. A small, nonsignificant increase in LIMA blood flow occurred during the 15-minute study period (30 +/- 12 to 35 +/- 10 mL/min) in patients who received fenoldopam. No significant changes occurred in the placebo group.

CONCLUSIONS

The findings indicate that fenoldopam, 0.1 microg/kg/min, did not influence coronary conduit blood flow to a clinically significant extent. The small increase in LIMA blood flow may be of greater importance in high-risk patients or in the prevention of coronary arterial spasm.

Histologic and physiologic evaluation of skeletonized internal thoracic artery harvesting with an ultrasonic scalpel

OBJECTIVES

The safety and reliability of a method of skeletonized internal thoracic artery harvesting with an ultrasonic scalpel (Harmonic Scalpel; Ethicon Endo-Surgery, CVG, Cincinnati, Ohio) were evaluated.

METHODS

The mural branches of the internal thoracic artery were cut by means of 3 methods, differentiated by distance from the site of application of the Harmonic Scalpel blade to the internal thoracic artery. A total of 15 branches were cut from the internal thoracic artery at (0 mm) the origin (group I) or at 1 mm (group II) or 2 mm (group III) distal to the origin. Tissue preparations were examined for successful vessel closure and severity of tissue damage. The length of stump (L) and the length of tissue damage from the stump (D) were determined by a computer image analysis system, and pressure testing was performed to evaluate the physical strength of vessel closure.

RESULTS

In group I, 8 of the 15 branches exhibited discontinuity of the vascular wall structure, probably because of insufficient sealing of the divided section, and 12 of the 15 branches exhibited tissue denaturation on the internal thoracic artery wall adjacent to areas of origin, which was probably caused by the heat transferred from the branches during the process of coagulation. In groups II and III, continuity of wall structure of stumps suggestive of stable closure of branches was confirmed. The lengths of tissue damage from the stump (D) were 0.96, 0.58, and 0.63 mm in groups I, II, and III, respectively, and the lengths of intact area (L - D) in the corresponding groups were -0.78, 0.61, and 1.51 mm. The negative figure in group I indicates the presence of tissue damage in the internal thoracic artery itself. By contrast, in groups II and III the internal thoracic arteries were intact, with a safety margin of greater than 0.5 mm. On physiologic evaluation of vessel closure, 2 of the 24 (8.3%) branches burst under a pressure lower than 350 mm Hg because of insufficient vessel coagulation, but the remaining 22 branches (91.7%) remained intact under pressures up to 350 mm Hg.

CONCLUSION

The internal thoracic artery skeletonization method with an ultrasonic scalpel (Harmonic Scalpel: output level 2) appears to be a safe and reliable method of skeletonized internal thoracic artery harvesting when branches are sectioned at least 1 mm distal to their origin at a sufficiently slow speed.

Impact of sequential grafting of the internal thoracic or right gastroepiploic arteries on multiple coronary revascularization

OBJECTIVE

The aim of the study is to clarify the efficacy of the sequential anastomotic technique of the arterial conduits for multiple coronary revascularization.

BACKGROUND

The internal thoracic artery (ITA) is now widely accepted as a durable conduit for myocardial revascularization. The right gastroepiploic artery (GEA) has been developed as a third in situ arterial graft with an outcome similar to that of the ITA.

MATERIAL AND METHOD

One hundred and forty five consecutive patients (116 male, 29 female, mean age 60.4yr) who received sequential grafting of either the ITA or GEA or both were retrospectively analysed.

RESULTS

Sequential anastomoses were performed in 121 in situ left ITAs, 36 in situ GEAs and 12 composite right ITAs. No in situ right ITA was anastomosed sequentially. Two to six vessels (mean 3.8) were revascularized for each patient. Of the total 543 bypassed vessels, 432 (79.6%) were reconstructed with the arterial grafts. In 85 patients with quadruple bypass or more, the arterial grafts were able to reconstruct 266 out of 360 (74.0%) target vessels. Seventy one patients (49.0%) were revascularized without venous grafts. The arterial grafts could revascularize 293 out of 310 vessels (94.5%) in the LAD approximately Diagonal region, 83 out of 113 (73.4%) in the distal RCA or Cx region. There were no cardiac events responsible for the arterial grafts in the follow up period.

CONCLUSION

In light of our experience, multiple revascularization with in situ arterial sequential grafts is feasible. Aggressive application of this technique provides patients requiring multiple coronary revascularization with favorable long-term results.

Internal mammary artery harvesting using the harmonic scalpel

Internal mammary artery (IMA) harvesting using the harmonic scalpel (HS) was recently introduced. We studied 541 IMAs harvested by the same surgeon through a standard median sternotomy in 472 coronary bypass patients; 252 (47%) with the HS, while 289 (53%) were with electrocautery (EC). Patient demographics included mean ages: 67 years HS vs. 65 years EC (p = NS); male:female ratio: 3:1; and insulin dependent diabetes mellitus (IDDM): 11% HS vs. 12.5% EC (NS). Mean ultrasonic IMA flow at a mean SBP of 70 mm Hg in 10 consecutive patients of each group were: preharvest, HS 11.9 +/- 2.3 ml/min vs. EC 8.5 +/- 1.6 ml/min (p = 0.256); postharvest, HS 35.7 +/- 10.7 ml/min vs. EC 22 +/- 2.9 ml/min (0.235); and postcardiopulmonary bypass (post-CPB), HS 47.8 +/- 6.2 ml/min vs. EC 41.7 +/- 2.5 ml/min (0.381). Histologic samples of 50 consecutive IMAs showed no evidence of vessel injury in either group. Clinical results revealed postoperative bleeding in 6/217 (2.7%) HS vs. 7/255 (2.7%) EC (p = 0.783), none attributed to bleeding from the IMA; phrenic paresis: 0/217 in HS but 1/255 (0.4%) in EC (p = 0.960); sternal wound infection: 5/217 (2.3%) HS vs. 6/255 (2.4%) EC (p = 0.787); postoperative IABP: 6/217 (2.7%) HS vs. 5/255 (2%) EC (p = 0.859); mortality: 2/217 (0.9%) HS vs. 2/255 (0.8%) EC (p = 0.710). Hemodynamic, histologic, and clinical results were comparable in both groups. The authors believe the HS is safe and effective for IMA harvesting.

Assessment of sternal vascularity with single photon emission computed tomography after harvesting of the internal thoracic artery

OBJECTIVE

This study prospectively evaluates the effect on sternal vascularity of harvesting the left internal thoracic artery.

METHODS

Twenty-four consecutive patients undergoing primary coronary artery bypass grafting were studied. One patient's procedure was altered during the operation, and he was eliminated from the study. The patients were prospectively randomized to receive a skeletonized internal thoracic artery (group I, n = 11) or a pedicled internal thoracic artery (group II, n = 12) graft. Each patient underwent a preoperative technetium 99 methylene diphosphonate bone scan using single photon emission computed tomography. The ratio of the mean counts per pixel on the left side of the sternum was compared with the mean counts per pixel on the right side. Postoperatively, all patients had a second scan, and sternal uptake was compared with the preoperative uptake.

RESULTS

No significant differences in preoperative and operative variables were observed between the groups. A statistically significant reduction in blood flow to the left side of the sternum was shown postoperatively in group II compared with group I (0.61 +/- 0.11 vs 0.85 +/- 0.09; P <.001). Multivariable logistic regression analysis of preoperative and operative variables revealed only a pedicled left internal thoracic artery to be associated with a 20% or more reduction in left-to-right sternal activity ratio (odds ratio, 100; 70% confidence limits, 22-465; P =.002).

CONCLUSION

A pedicled left internal thoracic artery graft to the left anterior descending artery reduces blood flow to the left side of the sternum during the acute postoperative period. This does not occur when the left internal thoracic artery is skeletonized.

[Arterial myocardial revascularization in the 9th decade of life. Personal results and review of the literature]

The rate of the population being 80 years of age and even older, has an increasing tendency in the Federal Republic of Germany. In 1996, a total of 87,372 patients received surgery supported by the heart-lung-machine, 2,383 patients out of these (2.7%) were 80 years of age and older. In view of the limited life expectance, the arterial revascularization in this age category is faced with controverse discussions. We analysed our patients in relation to this aspect. Between January 1, 1995 and June 30, 1997, 4,338 patients underwent surgery supported by the heart-lung-machine. Hundred and fifty-five out of these (3.6%) were in the 9th decade of life. Seventy-seven patients out of the 155 (49.7%, 34 women, 43 men, 80 to 88 years old, mean: 82 years of age) underwent an isolated myocardial revascularization. We performed 55 (71%) elective, 16 (21%) urgent and 6 (8%) emergency surgeries. Twelve patients (15.6%) solely received venous bypasses (Group I), 65 (84.4%) additionally also received unilateral bypasses of the internal mammaria artery (IMA) (Group II). Three patients died at our facility (3.9%), 3 further patients died during the follow-up treatment in outlying hospitals, the in-patient mortality rate in Group I therefore presented a rate of 8.3%, in Group II 7.7% and in total, a rate of 7.8%. In 1996, the in-patient mortality rate could be reduced to 3.6%. The follow-up observation time ranged between 7 and 138 weeks (median 44 weeks). The survival rate for patients with an IMA-bypass after 1 year was 86.3%, after 2 years 77%, and for the entire collective 85.3% and 75%. Whereas 96% of the patients could pre-operatively be related to Class III or IV of the NYHA-classification, 55 of the 63 survivors (87%) belonged to Class I (6%) or II (81%). Two Group I patients (22.2%), 3 Group II patients (5.6%) and 7.9% of the total collective complained about repeated angina symptoms. The myocardial revascularization with the internal mammaria artery performed on patients in the 9th decade of life, achieves an acceptable morbidity and mortality compared to solely venous coronary bypasses. The more prolonged follow-up observation period will clarify, whether the arterial myocardial revascularization also proves to be the superior method in this age category.

Long-term patency rate of right internal thoracic artery bypass via the transverse sinus

BACKGROUND

Although concern regarding patency and possible compromise of graft blood flow by routing the right internal thoracic artery (RITA) through the transverse sinus has been raised, little is known about long-term patency.

METHODS AND RESULTS

To evaluate long-term patency of in situ RITA bypass via the transverse sinus, our first 115 patients (94 men, 21 women; mean age, 62.5 years; range, 13 to 77 years) who were alive in 1998 were enrolled for angiographic study. Only good-caliber grafts with no occlusion, string sign, or significant stenosis were considered patent. Early postoperative angiography had been performed 2 to 3 weeks after surgery in 114 patients. The early patency rates were 97.1% for RITA and 95.4% for left internal thoracic artery (LITA) grafts. Of 109 long-term survivors, 73 (67.0%) consented to have late angiographic restudy at a mean of 59 months (range, 9 to 93 months); 89.9% of RITA and 92.3% of LITA grafts were patent. Cumulative patency rates (actuarial curves) at 6 years were 89.3% (95% CI, 85% to 94%) for RITA and 94.5% (95% CI, 92% to 97%) for LITA, the differences not reaching statistical significance (multivariate Cox analysis).

CONCLUSIONS

Our study demonstrated good long-term patency of in situ RITA bypass grafting via the transverse sinus for revascularization of the circumflex and diagonal arteries and supports its continued use.

Arterial graft patency in coronary artery bypass grafting: what do we really know?

BACKGROUND

With increasing use of beating heart techniques for bypass of the left anterior descending coronary artery with the left internal mammary artery (LIMA), appropriate concerns have been raised of whether graft patency by these techniques compares favorably with conventional, arrested heart techniques.

METHODS

All published articles that examine outcome efficacy of the LIMA graft to the left anterior descending coronary artery were reviewed. Because angiography has been considered the "gold standard," only those studies that included angiographic follow-up were analyzed.

RESULTS

From 1972 through 1998, there have been 37 peer-reviewed publications that examined outcomes of LIMA grafting in conventional coronary bypass grafting, of which 27 contained angiographic follow-up data. The completeness of angiographic follow-up was variable, but early graft patency (< or =1 month) in studied patients ranged between 94% and 99%. Late graft patency (up to 15 years) ranged from 51% to 98%. Five recent series of minimally invasive direct coronary artery bypass grafting that contained LIMA graft patency data show early graft patency rates between 91% and 99%.

CONCLUSIONS

Meaningful comparison of LIMA graft patency between arrested heart, conventional coronary artery bypass grafting, and minimally invasive direct coronary artery bypass grafting is difficult; however, early graft patency by both techniques can confidently be stated as being 90% or greater.

Angiographic follow-up of internal thoracic artery for free bypass grafting

BACKGROUND

The use of free internal thoracic artery (ITA) grafts in patients with smaller body surface areas has been questioned because of technical difficulties and inadequate graft flow.

METHODS

To evaluate postoperative changes in the diameter of free ITA grafts, we performed coronary angiography immediately after coronary artery bypass grafting and then again at a mean of 42 +/- 6 months later. In 20 consecutively treated patients, 21 free ITAs were used as bypass conduits. Two ITA grafts that were patent at the time of the first angiography had closed at the second angiography. Postoperative changes in ITA graft diameter were measured in the 19 patent ITA grafts.

RESULTS

At the first angiography, the mean diameters of the proximal, middle, and distal ITA grafts were 2.28 +/- 0.45 mm, 2.34 +/- 0.39 mm, and 2.12 +/- 0.38 mm, respectively. At the second angiography, the mean diameters of the proximal, middle, and distal ITA grafts were 2.85 +/- 0.50 mm, 2.89 +/- 0.53 mm, and 2.72 +/- 0.53 mm, respectively. All segments of the ITA grafts had dilated significantly between the first and second angiographic evaluations (p < 0.01). The percentage change in graft diameter was greater when the initial ITA diameter was less than 2.3 mm (32.0% +/- 28.0%) than when it was 2.3 mm or more (18.8% +/- 11.3%) (p < 0.05).

CONCLUSIONS

The postoperative increase in free ITA graft diameter depends on coronary blood flow requirements.

Prediction of death and myocardial infarction by screening with exercise-thallium testing after coronary-artery-bypass grafting

BACKGROUND

The role of myocardial-perfusion imaging in calculating risk in symptom-free patients who have had coronary-artery-bypass grafting (CABG) is unclear. Practice guidelines have argued against routine screening of these patients. We sought to find out the independent and incremental prognostic value of exercise thallium-201 single-photon-emission computed tomography (SPECT) for prediction of death and non-fatal myocardial infarction (MI) in these patients.

METHODS

Analyses were based on 873 symptom-free patients undergoing symptom-limited exercise thallium-201 SPECT between September, 1990, and December, 1993. All had undergone CABG and none had recurrent angina or other major intercurrent coronary events. Exercise and thallium-perfusion variables were analysed to determine their prognostic importance during 3 years of follow-up.

FINDINGS

Myocardial-perfusion defects were noted in 508 (58%) patients. There were 57 deaths and 72 patients had major events (death or non-fatal MI). Patients with thallium-perfusion defects were more likely to die (9% vs 3%, p=0.0004) or suffer a major event (11% vs 4%, p=0.0002). Reversible defects were also predictive of death (12% vs 5%, p=0.002) and major events (13% vs 7%, p=0.004). The exercise variable with the strongest predictive power was an impaired (< or = 6 METs [measure of oxygen consumption equal to 3.5 mL/kg/min]) exercise capacity; poor exercise capacity was predictive of death (18% vs 4%, p<0.0001) and death or non-fatal MI (19% vs 5%, p<.00001). After adjusting for baseline clinical variables, surgical variables, time elapsed since CABG, and standard cardiovascular risk factors, thallium-perfusion defects remained predictive of death (adjusted relative risk 2.78, 95% CI 1.44-5.39) and major events (2.63, 1.49-4.66). Similarly, impaired exercise remained strongly predictive of death (4.16, 2.38-7.29) and major events (3.61, 2.22-5.87) after adjusting for confounders.

INTERPRETATION

In this group of patients who were symptom-free after CABG, thallium-perfusion defects and impaired exercise capacity were strong and independent predictors of subsequent death or non-fatal MI. Recommendations against routine screening exercise myocardial-perfusion studies in this setting should be reconsidered.

Internal mammary hypoperfusion syndrome--diagnosis and treatment

The use of the internal mammary artery (IMA) in coronary artery bypass surgery has increased substantially over the past 20 years, being at present the conduit of choice for most patients. Complications associated with its use occur occasionally and include life-threatening postoperative ischemia or the revascularized myocardium. We reviewed the records of 1,971 consecutive patients who underwent coronary artery bypass grafting over a 5-year period. All operations included an IMA graft to the left anterior descending coronary artery. Twenty-eight of these patients (1.4%) underwent additional placement of a vein graft on the same region as a salvage maneuver for suspected hypoperfusion as a result of IMA failure. All 28 patients showed life-threatening hemodynamic compromise. Twenty-two of the 28 patients (79%) survived. This was the result of immediate surgical correction, which reversed their hemodynamic instability. IMA hypoperfusion was found more frequently in reoperations and in women and diabetic patients. This syndrome is the result of an imbalance between IMA flow and myocardial demand, causing sudden and unexpected myocardial failure. Its detection and expeditious treatment can successfully modify a serious and potentially lethal clinical situation.

Intermediate clinical results of combined gastroepiploic and internal thoracic artery bypass

BACKGROUND

To improve the postoperative results of coronary artery bypass grafting (CABG), the internal thoracic artery (ITA) has become the conduit of choice, with a low operative risk. The gastroepiploic artery as a third arterial conduit for grafting was first reported in 1987, and the early results were reported to be as good as those for the ITA graft. In this report, we present the intermediate-term results of combining ITA and gastroepiploic artery grafts up to 7 years after the operation.

METHODS

Between April 1988 and April 1992, 214 patients received CABG with at least one ITA graft and were followed up for more than 3 years. They were divided into two groups: Group I consisted of 155 patients who had CABG using one ITA with or without saphenous vein grafts, and group II consisted of 59 patients who had CABG using an ITA and a gastroepiploic artery with or without saphenous vein grafts. The duration of follow-up for hospital survivors ranged from 36 to 89 months.

RESULTS

There were six late cardiac deaths in group I and one in group II. Fifteen patients complained of recurrent symptoms of angina: 13 in group I and 2 in group II. The actuarial survival rate excluding noncardiac deaths was 95.9% in group I and 96.8% in group II at 7 years (p = not significant). The cardiac event-free rate was 75.4% in group I and 92.2% in group II, which was a significant difference (p < 0.05).

CONCLUSIONS

When using both the ITA and gastroepiploic artery, CABG can be performed with minimal operative risk and seems to offer an improved quality of life at least 7 years postoperatively.

Exclusive use of arterial grafts in coronary artery bypass operations for three-vessel disease: use of both thoracic arteries and the gastroepiploic artery in 256 consecutive patients

METHODS

From September 1989 to September 1994 we operated on a consecutive group of 256 patients with three-vessel disease in whom we used the right gastroepiploic artery together with both internal thoracic arteries. Vein grafts were not used in these patients. This population consisted of 233 men and 23 women whose ages ranged from 31 to 77 years (mean age 57.8 years).

RESULTS

Hospital morbidity and mortality were not directly related to the use of the gastroepiploic artery. Patency of the anastomoses in a subgroup of 56 patients (22%) a mean of 16 months after the operation was 98% for the left internal thoracic artery, 96% for the right internal thoracic artery, and 88% for the gastroepiploic artery. Five-year actuarial survival (including in-hospital deaths) was 95.9% and was related only to age. From discharge until the end of follow-up, two patients had a myocardial infarction, six patients underwent a reintervention procedure, and 18 patients had a return of angina pectoris.

CONCLUSION

We conclude that the concomitant use of the gastroepiploic artery with the both internal thoracic arteries has low morbidity and mortality in patients with three-vessel disease operated on by experienced surgeons. At this moment, we have no reason to believe graft patency will deteriorate in the future. On the basis of these results, the knowledge that arteries are to be preferred over veins for coronary bypass grafting, and the absence of a leg incision, we believe this operative technique is superior to the use of venous grafts.

In situ right internal thoracic artery graft via transverse sinus for revascularization of posterolateral wall: early results in 116 cases

The in situ right internal thoracic artery graft brought through the transverse sinus was used to revascularize the posterolateral wall in 116 patients. Its advantages were assessed retrospectively. The graft was anastomosed to the circumflex marginal branch in 70 patients (60%) or to the posterolateral branch in 41 patients (35%). One patient died (mortality rate 0.9%). Perioperative myocardial infarction occurred outside the territory of the right internal thoracic artery graft in 10 patients, four of whom required mechanical support for hemodynamic deterioration. Postoperative early angiography in 114 patients found the graft to be patent in 97.4%. The ratio of the diameter of the right internal thoracic artery to that of the recipient marginal branch was 0.94 +/- 0.18 (n = 69), and that to the posterolateral branch was 0.88 +/- 0.18 (n = 37) (not significantly different). Results of a postoperative stress test were abnormal in one patient (1/96 tested patients). This retrospective study suggests that the right internal thoracic artery brought through the transverse sinus to revascularize the posterolateral wall provided excellent early patency and good clinical results, even to the most distally located branches. This continues to be our procedure of choice for patients with multivessel coronary disease.

Effect of normothermic papaverine to relieve intraoperative spasm of the internal thoracic artery

BACKGROUND

After mobilization, vasospasm often reduces flow through the internal thoracic artery. An established method of relaxing the artery and increasing flow is to use papaverine at ambient temperature (20 degrees to 22 degrees C) as a topical vasodilator. However, the pharmacologic actions of papaverine generally have been assessed at 37 degrees C.

METHODS

In 60 patients in whom the left internal thoracic artery was used for myocardial revascularization, we investigated the effects of normal saline solution at 20 degrees C (group I), papaverine at 20 degrees C (group II), and papaverine at 37 degrees C (group III). Under controlled hemodynamic conditions, free flow was measured before any pharmacologic intervention and a median of 16 minutes after the pedicle had been sprayed with one of the agents.

RESULTS

Normal saline solution at 20 degrees C produced a small increase in flow from 37.5 +/- 8.1 mL/min to 50 +/- 10.2 mL/min. A significant increase occurred with papaverine at 20 degrees C, from 38.05 +/- 6.5 mL/min to 78.75 +/- 21.2 mL/min (p < 0.0001). Papaverine at 37 degrees C, however, produced an increase in flow from 36.9 +/- 12.6 mL/min to 103.3 +/- 44.6 mL/min (p < 0.0001) and proved to be more effective than papaverine at room temperature (p = 0.0174).

CONCLUSIONS

We recommend topical use of papaverine at 37 degrees C to relieve intraoperative spasm of the internal thoracic artery.

Skeletonized and pedicled internal thoracic artery grafts: effect on free flow during bypass

BACKGROUND

The skeletonization technique of the internal thoracic artery (ITA) is used as a dissection technique for myocardial revascularization procedures. This study compared free flow between skeletonized ITA grafts and ITA pedicled grafts.

METHODS

The ITA pedicled grafts were sprayed and wrapped in sponges soaked in dilute papaverine solution in 14 patients and prepared with intraluminal papaverine injection in 18 patients. For 23 other patients, the ITA was skeletonized. We measured the first free flow from the distal ITA early after the start of cardiopulmonary bypass and the second free flow just before the ITA was grafted to the left anterior descending artery.

RESULTS

The first flow was greater in the skeletonized ITAs than in the ITA pedicled grafts with topical application of papaverine alone (38.9 +/- 15.8 versus 18.0 +/- 6.8 mL/min; p < 0.001). For the second flow, the pedicle grafts with intraluminal papaverine injection and the skeletonized ITAs showed greater flow rate than the pedicled grafts with topical application of papaverine (67.4 +/- 25.5 and 59.7 +/- 22.5 versus 38.1 +/- 13.1 mL/min; p < 0.005 and p < 0.05, respectively), but there was no significant difference between the former two groups (p = 0.53).

CONCLUSIONS

Skeletonization of the ITA is as efficient a strategy to increase the flow as intraluminal papaverine injection for the ITA pedicled graft. When the ITA is harvested in a skeletonized fashion, arterial spasm and reduced early flow can be avoided, even without intraluminal injection of papaverine.

High flow demand on small arterial coronary bypass conduits promotes graft spasm

Despite the superior long-term patency of arterial grafts, surgeons are often reluctant to use arterial grafts on coronary vessels that supply large areas of myocardium because postoperative shock may occur. We hypothesized that supramaximal flow through small arterial conduits would decrease distal intraluminal pressure, thereby reducing afterload on the smooth muscle and rendering the arterial graft vulnerable to spasm. Fourteen internal thoracic and eight gastroepiploic arteries were harvested from adult pigs (220 to 250 pounds). Arteries were mounted on a computer-controlled perfusion system with inflow pressure at 80 mm Hg and outflow resistance adjusted to simulate normal (in situ) or supramaximal (coronary artery bypass graft) flow demands. Artery pressures and flow rates were measured at baseline and after norepinephrine was added to the system. Internal thoracic arteries had no hemodynamic response to norepinephrine at normal flow. Under supramaximal flow demands, large internal thoracic arteries (2.5 to 3.0 mm) had no hemodynamic response to norepinephrine. However, for small internal thoracic arteries (2.1 to 2.9 mm), norepinephrine reduced distal internal thoracic arterial pressure (63.2 +/- 2.2 to 27.0 +/- 1.9 mm Hg) and flow rate (99.4 +/- 5.0 to 45.4 +/- 2.7 ml/min, median effective dose = 9.12 x 10(-9) mol/L). Under normal flow demands, the flow rate in gastroepiploic arteries (1.0 to 2.0 mm diameter) decreased (14.1 +/- 0.5 to 4.8 +/- 0.8 ml/min, p < 0.05) only at high concentrations of norepinephrine (median effective dose = 1.26 x 10(-6) mol/L). Supramaximal flow demands reduced distal gastroepiploic arterial pressure (77.5 +/- 0.5 to 49.5 +/- 3.8 mm Hg, p < 0.05), which resulted in a greater decrease in flow rate (80.0 +/- 3.7 to 6.8 +/- 1.6 ml/min, p < 0.05) at lower concentrations of norepinephrine, (median effective dose = 3.24 x 10(-8) mol/L, p < 0.05). In four studies in internal thoracic arteries and eight in gastroepiploic arteries, arteries were cut in half, reattached, and reperfused. The proximal half of the internal thoracic artery did not respond to norepinephrine, but the distal half had a 53% +/- 7% decrease in flow. Both gastroepiploic artery halves reacted and flow rate decreased by 88% +/- 2% (proximal half) and 89% +/- 3% (distal half). In conclusion, small arterial conduits develop large transconduit pressure gradients under supramaximal flow demands. Under these conditions, arteries are very sensitive to vasoconstrictors and flow may cease with higher drug concentrations.(ABSTRACT TRUNCATED AT 400 WORDS)

Right Gastroepiploic Artery in Myocardial Revascularization: Portuguese Experience

Excellent results obtained with the use of the internal mammary artery in myocardial revascularization led us to complement its use with other arterial conduits, and the right gastroepiploic artery (RGEA) emerged as a valid alternative, allowing the expansion of total arterial revascularization. From July 1988 until September 1994 we utilized the RGEA in 101 patients with ages between 30 and 71 years (mean 54 9.43). The RGEA was used to bypass the posterior descending artery in 90 patients and for the marginal branches of the circumflex in 11. Exclusive arterial revascularization was possible in 92% of the cases with a mean of 2.7 bypasses per patient. There were 4 (4%) cases of death, and 3 instances of perioperative myocardial infarction. Angiographic control of the RGEA performed in 46 patients showed a patency of 87%. In conclusion, the RGEA was predominantly used to revascularize the inferior wall of the myocardium as a complement to the internal mammary artery. Its use occurred without significant morbidity and mortality, and postoperative angiographic visualization of these arterial conduits allowed us to expect good mid-and long-term patency.

Reimplantation of the right internal thoracic artery as a free graft into the left in situ internal thoracic artery (Y procedure). One-year angiographic results

Reimplantation of the right internal thoracic artery, as a free graft, into the left in situ internal thoracic artery (Y procedure) has enabled us to bypass more distant marginal vessels, which was not possible by the bilateral technique alone. This prospective study was aimed at evaluating the clinical state of the patients and the degree of patency of grafts within 16 months of follow-up. All 80 patients who underwent the Y procedure between January 1988 and January 1992 were included. This group represented 10% of the 840 patients having coronary bypass during the same period. A total of 202 coronary anastomoses were performed in this series. Early postoperative (30 days) complications included three deaths (3.75%), eight myocardial infarctions (10%), one case of phrenic nerve paralysis (1.25%), two cases of respiratory failure (2.5%), and six wound infections (7.5%). At 3 months' follow-up, 96% of patients were free of symptoms. During the follow-up period, four patients died of noncardiac causes (lung, pancreatic, and brain cancer and rupture of an abdominal aortic aneurysm). At 1 year, 71 patients were free of symptoms (97%). Sixty-one patients underwent coronary angiography between 12 and 24 months. Six patients with peripheral arterial disease were not suitable for coronary angiography, and six refused to be tested. These 12 patients had normal thallium test results in the bypassed area (stress or dipyridamole test). The patency rate of the left internal thoracic artery was 98.3% (n = 60), occlusion rate 1.6% (n = 1), and incidence of threadlike arteries 4.9% (n = 3). Thus the rate of perfect patency was 93.4%. The patency rate of the right internal thoracic artery as a free graft was 93.4% (n = 57), occlusion rate 6.5% (n = 4), and the incidence of threadlike arteries 8% (n = 5). Thus the rate of perfect patency was 85.2%. A total of 169 anastomoses were studied. The rate of patency of the anastomoses to the left anterior descending coronary artery was 96% (n = 58) and the occlusion rate, 4% (n = 2). The patency rate of sequential anastomoses (side to side) to diagonal arteries was 100% (n = 16). Patency rate of anastomoses to obtuse marginal arteries was 95% (n = 58) and the rate of occlusion, 4.9% (n = 3). The patency rate of anastomoses to the posterior descending artery or distal branches of the right coronary artery was 80% (n = 4/5).(ABSTRACT TRUNCATED AT 400 WORDS)

Treatment of a giant coronary artery aneurysm in an adult with a history of Kawasaki disease by resection and bypass grafting: report of a case

We report herein the case of a 22-year-old man with a history of Kawasaki disease who developed a giant calcified aneurysm of the left main coronary artery. The aneurysm was successfully resected and coronary bypass surgery was performed using the bilateral internal thoracic arteries. The resected aneurysm, the maximal diameter of which was 27 mm, showed heavy calcification of the inner layer and extended into the adjacent coronary arteries, producing a significant narrowing of the lumen of both the left main trunk (50%) and the anterior descending branch (50%). Extensive intimal calcification presumably prevented normal luminal development and produced a significant narrowing as the patient grew into adulthood. A cause for stenotic lesions developing in the coronary artery adjacent to a coronary aneurysm in adults with a history of Kawasaki disease is suggested here by the resected aneurysm seen in this patient. Thus, adult patients with giant coronary artery aneurysms and significant stenotic lesions of the coronary artery associated with Kawasaki disease may require aneurysmectomy in addition to bypass surgery.

Bilateral vs single internal thoracic artery grafting for left main coronary artery occlusion

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.

Five-year follow-up of microsurgical multiple internal thoracic artery grafts

In a consecutive series of 143 patients requiring multiple coronary artery bypass grafts, 317 of 441 anastomoses (72%) were constructed from internal thoracic arteries. Of these 143 patients, 103 had bilateral, 51 sequential, and 49 free internal thoracic artery grafts. When compared with an earlier series of 494 patients who underwent only one internal thoracic artery anastomosis, the surgical morbidity and mortality were not increased, but, during 5 years of follow-up, the incidences of postoperative angina and myocardial infarction were found to decrease significantly--32.5% versus 10.5% (p < 0.001) and 5.7% versus 1.4% (p < 0.03), respectively. We conclude that, for patients with multivessel disease, multiple internal thoracic artery grafts confer better protection from the clinical manifestations of ischemic heart disease than does one internal thoracic artery graft. The use of high magnification (8 to 12x, surgical microscope) was essential to the success of this method.

Prostacyclin production by different human grafts employed in coronary operations

Segments of human saphenous vein, internal mammary artery, right gastroepiploic artery, and inferior epigastric artery were incubated in vitro in Krebs-Henseleit solution and compared in terms of their capacity to generate and release into the medium 6-keto-prostaglandin F1 alpha (PGF1 alpha), the stable metabolite of prostacyclin. The four vascular conduits were also challenged with endothelin-1 (40 ng/mL), and accumulation of the lipidic material in the bathing fluid was also studied. The results obtained show clearly that under both normal and endothelin-1-stimulated conditions, the four vascular segments generate a substantial amount of 6-keto-PGF1 alpha. Multiple-comparisons analysis of the results indicates that the rank order in producing 6-keto-PGF1 alpha is as follows: inferior epigastric artery > internal mammary artery > right gastroepiploic artery > saphenous vein (p < 0.01). A similar order of potency was obtained in vascular conduits stimulated with endothelin-1. The rate of formation of immunoreactive 6-keto-PGF1 alpha under both normal and stimulated conditions by the inferior epigastric artery (normal, 301 +/- 8 pg/mg of tissue; stimulated, 519 +/- 15 pg/mg of tissue) was at 10 minutes more than 2 times (p < 0.01) that of the saphenous vein and about 1.5 times (p < 0.01) that of the right gastroepiploic artery.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibitory effects of calcium antagonists on alpha-adrenoceptor-mediated contraction in the human internal mammary artery

1. The internal mammary artery has become a preferred coronary bypass graft. Sympathomimetic amines are spasmogens for vasospasm and calcium antagonists are frequently administered drugs perioperatively. The effect of calcium antagonists on alpha-adrenoceptor-mediated contraction depends on the subtype of alpha-adrenoceptor and the type of origin of vascular smooth muscle. This study was designed to investigate the effect of calcium antagonists on alpha-adrenoceptor-mediated contraction in the IMA. 2. Human IMA segments taken from 22 patients undergoing IMA--coronary artery bypass grafting were mounted in an organ bath under the physiological pressure determined from their own length-tension curves. 3. Three ring segments were allocated into three groups. One served as a control and the others were treated with clinically related concentrations of nifedipine (20 or 200 nM) for 25 min before concentration-contraction curves to alpha 1-adrenoceptor agonist methoxamine (MO) or full alpha-adrenoceptor agonist noradrenaline (NA) were established. 4. In separate experiments, the concentration-relaxation curves to nifedipine were established in the IMA rings precontracted with MO (30 microM) or NA (10 microM). Glyceryl trinitrate (GTN, 3 microM) was added to further relax the vessels. 5. Pretreatment with nifedipine (200 nM) only slightly inhibited the MO- (1.74 +/- 0.32 vs 2.88 +/- 0.56 g) or NA- (2.43 +/- 0.66 vs 3.60 +/- 0.82 g) induced contraction without statistical significance (P > 0.05). 6. On the other hand, nifedipine only caused 34.49% relaxation in the MO-precontracted and 24.39% relaxation in the NA-precontracted IMAs. In contrast, GTN caused 76.16% (against MO, P < 0.05) or 92.22% (against NA, P < 0.0001) relaxation.(ABSTRACT TRUNCATED AT 250 WORDS)

Conjoined double internal mammary artery grafting

Double internal mammary artery (IMA) grafting to the coronary arteries was performed on 82 patients. In ten of them one IMA was used as a free graft, and was proximally connected to the other ("conjoined" double IMA), the indications being insufficient supply of adequate veins, diseased aortic wall, availability of only a short right IMA segment for free grafting, occluded left subclavian artery, and when distal and scattered lesions of relatively important vessels had to be bypassed. Additional sequential IMA anastomoses were performed in four patients and an additional sequential vein graft in a fifth. All patients became angina-free postoperatively and have remained so during observation up to 16 months. Recatheterization studies were performed in six patients and in all of them the IMA-to-IMA (n = 6) and distal anastomoses (n = 26) were patent. Conjoined double IMA grafting is an important option available to the cardiac surgeon for management of selected patients with coronary artery disease.

Bilateral mammary artery grafting: avoidance of complications with extended use

This study was undertaken to more clearly define the operative risks and appropriate strategies for the selection of patients who might be candidates for bilateral internal mammary artery grafting. A review of the 674 patients who underwent this procedure was performed over a 10-year period from January 1982 through 1991. These patients represented 5% of the 12,824 patients who underwent bypass grafting during this period. The mean patient age was 54 +/- 9.4 years, and 92% of the patient were male. Diabetes was present in 17.5%, with 24% of this group insulin dependent. The ejection fraction was less than 0.50 in 26.7% and 14% had had previous bypass procedures. Hospital mortality was 1.9% (n = 13). Hospital morbidity included wound infection in 3.6%, reoperation for bleeding in 2.1%, and stroke in 1.6%. Postoperative intraaortic balloon pump support was necessary in 2.8%. Univariate and multivariate analysis revealed that advanced age, an emergent operative status, and the number of diseased vessels (especially left main obstruction) were predictors of hospital death. Except for wound infection (9.3% versus 2.5%) and length of hospital stay (10.8 +/- 11.8 days versus 8.8 +/- 7.6 days), the complications in diabetics were similar to those in patients without diabetes, respectively. At 5 years, freedom from death, death or infarctions, and death, myocardial infarction, or coronary reoperation was 90%, 70%, and 62%, respectively. The only significant multivariate correlates of long-term survival were diabetes and reoperative surgery.