Identification of a novel HLA-B allele, B*46:39, by sequence-based typing.

The new allele B*46:39 showed a single-nucleotide substitution compared with B*46:01 at codon 185 (CCA/ACA).

Influence of ventricular morphology on outcome after the Fontan procedure.

The modified Fontan procedure has gained wide acceptance in the treatment of various congenital heart defects. Determination of risk factors for mortality remains an important issue for optimizing patient selection for the Fontan procedure. Conflicting results have been reported about whether ventricular morphology is a risk factor in these patients. Survival free of Fontan takedown or cardiac transplantation was assessed in the first 500 patients undergoing the Fontan procedure at our institution. This survival was correlated with ventricular morphology as evaluated by angiography. Both multivariate and univariate analyses indicated ventricular morphology was predictive of early survival free of Fontan takedown or cardiac transplantation following the procedure. However, there was no statistical evidence for ventricular morphology being a risk factor for mortality in patients alive 6 months after the procedure. Ventricular morphology is a risk factor for early survival in patients undergoing a Fontan procedure, with left ventricular morphology associated with a better early survival than right ventricular morphology.

Repair of subaortic stenosis in atrioventricular canal with absent or restrictive interventricular communication by patch augmentation of ventricular septum, resuspension of atrioventricular valves, and septal myectomy.

OBJECTIVE: To describe a modification of a surgical technique for relief of subaortic stenosis in patients with atrioventricular canal. MATERIAL AND METHODS: We report an etiology-oriented modified technique of repair of subaortic stenosis after previous repair of atrioventricular canal, without (N = 2) or with (N = 1) a restrictive interventricular communication. RESULTS: In addition to a generous myectomy of the left ventricular septum, the technique consists of complete detachment of the left and right atrioventricular valves from the ventricular crest, patch augmentation of the concavity of the ventricular crest, and attachment of both atrioventricular valves at the superior aspect of the ventricular septal patch; thus, the septal leaflet of the left atrioventricular valve--in particular, its superior component--is lifted away from the elongated left ventricular outflow tract. CONCLUSION: This modification (as opposed to detachment of only the superior component of the septal leaflet of the left atrioventricular valve, as performed in previously proposed techniques) may be a valuable adjunctive technique to relieve subaortic obstruction associated with atrioventricular canal. In addition, this modification allows a secure anchoring of the patch to the right of the ventricular septum and therefore is associated with minimal risk of damaging the conduction tissue and of causing regurgitation of the left atrioventricular valve.

Congenital partial and complete absence of the pericardium.

Between 1952 and 1991, 15 Mayo patients were found to have partial or complete absence of the pericardium at the time of a cardiovascular surgical procedure. One patient with complete absence of the left pericardium had symptoms possibly related to the pericardial abnormality. This 42-year-old man had severe insufficiency of the tricuspid valve attributable to chordal rupture of the anterior leaflet, possibly precipitated by complete displacement of the heart into the left pleural space. Excision of the ruptured chordae and plication of the anterior flail leaflet rendered a competent tricuspid valve. In two patients, a small defect in the pericardium was repaired. Three patients who underwent operation for complex congenital heart disease died: two early postoperatively and one late after a reoperation. In the other 12 patients, no early or late postoperative complications were encountered. Although rare and usually asymptomatic, complete and partial deficiency of the pericardium may lead to serious complications such as cardiac valvular insufficiency or incarceration of cardiac tissue.

Surgical treatment of vascular rings: the Mayo Clinic experience.

From 1947 through 1992, 37 Mayo Clinic patients underwent operation for the relief of tracheoesophageal obstruction that resulted from vascular rings and related entities. Of the 37 patients, 18 had a double aortic arch, 11 had a right aortic arch with an aberrant left subclavian artery, 4 had a left aortic arch with an aberrant right subclavian artery, 2 had a pulmonary artery sling, 1 had a right aortic arch with mirror-image branching and a left ligamentum arteriosum, and 1 had a left aortic arch, a right descending aorta, and a right ductus arteriosus. Symptoms consisted of stridor, recurrent respiratory infections, and dysphagia. The anomaly was approached through a left thoracotomy in 31 patients, through a right thoracotomy in 4, and through a median sternotomy in 2. Only one early postoperative death (3%) and no late deaths occurred. At long-term follow-up (maximal duration, 45 years), three patients had residual symptomatic tracheomalacia, one of whom required right middle and lower lobectomy for recurrent pneumonia. Magnetic resonance imaging is the imaging technique of choice for accurate delineation of the vascular and tracheal anatomy. When patients are symptomatic, vascular ring should be repaired. The surgical risk is minimal, and the long-term results are excellent.

Aortopulmonary window: factors associated with early and late success after surgical treatment.

Between 1953 and 1990, 19 patients, who were from 7 weeks to 27 years old, underwent surgical correction of aortopulmonary window at the Mayo Clinic. Associated cardiac anomalies were present in nine patients (47%). At operation, extracorporeal circulation was used in all except one patient. In seven patients, division and primary closure were done. In four patients, the defect was closed by direct suture through a transpulmonary approach. In eight patients, the defect was closed with a patch through a transpulmonary or transaortic approach. Four deaths (21%) occurred intraoperatively or immediately postoperatively. All four patients had undergone division of the aortopulmonary window before 1962, and three of them had a pulmonary vascular resistance (Rp) that was 7.3 U.m2 or more and a ratio of Rp to systemic vascular resistance (Rp/Rs) that exceeded 0.6. One patient with an Rp of 11.8 U.m2 and an Rp/Rs of 0.72 died 16 years postoperatively. Statistical analysis of risk factors indicated that early year of operation (P = 0.022), division of the aortopulmonary window versus transaortic or transpulmonary closure (P = 0.009), and a high Rp/Rs (P = 0.021) were significantly associated with perioperative death. All patients with a preoperative Rp of 8 U.m2 or less, an Rp/Rs of less than 0.4, and no major associated cardiac anomalies were in functional class I (New York Heart Association) postoperatively. Our study confirms that infants with aortopulmonary window should undergo operation early, before irreversible pulmonary vascular changes have developed. Patients with an Rp/Rs that exceeds 0.4 should be thoroughly assessed to determine their operability.

Cor triatriatum: diagnosis, operative approach, and late results.

From May 1960 to January 1992, 13 patients with cor triatriatum underwent surgical correction at the Mayo Clinic. Their ages ranged from 7 months to 57 years. Four patients had isolated cor triatriatum; three others had an associated patent foramen ovale or atrial septal defect. Six patients had major associated cardiac anomalies. In patients who had isolated cor triatriatum or associated anomalies with high pulmonary blood flow, the mean gradient across the left atrial diaphragm was 24.4 mm Hg, in comparison with 11.6 mm Hg in patients who had cor triatriatum and a connection between the common pulmonary venous chamber and the right atrium or associated cardiac anomalies that restricted pulmonary blood flow. In all 11 patients who underwent angiography, echocardiography, or both at our institution, the correct diagnosis was established preoperatively. Currently, echocardiography is the procedure of choice for diagnosing cor triatriatum. The diaphragm was excised through a left atrial approach in seven patients and through a right atriotomy in six. All associated anomalies were corrected. One critically ill patient who underwent an emergency operation in 1963 died early postoperatively, and one patient with chromosomal abnormalities and multiple cardiac defects died 2 months after an uneventful postoperative course. At the time of follow-up of the 11 long-term survivors, 9 were in New York Heart Association functional class I, and 2 (both of whom had major associated cardiac anomalies) were in class II. Postoperative angiography or echocardiography (in nine patients) showed no residual interatrial shunt or recurrent left atrial diaphragm.

Preoperative diagnosis of coronary artery anatomy in dextrotransposition of the great arteries.

BACKGROUND: Preoperative diagnosis of the coronary artery pattern in dextrotransposition of the great arteries is important because deviation from the usual pattern may influence the surgical strategy. METHODS: For assessment of the value of angiography and echocardiography in this setting, we analyzed the preoperative echocardiographic and angiographic findings in 74 patients with dextrotransposition of the great arteries in whom an arterial switch operation was performed. RESULTS: Two-dimensional echocardiography established a diagnosis of the coronary artery pattern in 40 of the 74 patients; that diagnosis was correct in 38-30 of 32 (94%) with the usual coronary artery pattern and 8 (100%) with an atypical pattern. Angiography established a diagnosis of the coronary artery pattern in 52 patients; that diagnosis was correct in 50-41 of 42 (98%) with the usual coronary artery pattern and 9 of 10 (90%) with an atypical pattern. The accuracy of echocardiography in diagnosing the coronary artery pattern in dextrotransposition of the great arteries in this series was 95% and that of angiography was 96%. CONCLUSION: Both echocardiography and angiography can establish the diagnosis of the coronary artery anatomy in most patients. Echocardiography is routinely performed in infants with dextrotransposition of the great arteries and is proving to be increasingly sensitive for diagnosing the coronary artery anatomy; the role of angiography may evolve to be supplementary, especially in cases in which the coronary artery anatomy is not clearly demonstrated by echocardiography.

Instantaneous subaortic outflow obstruction after volume reduction in hearts with univentricular atrioventricular connection and discordant ventriculoarterial connection.

OBJECTIVE: To study the phenomenon of potential subaortic outflow obstruction after surgical volume unloading of the heart in patients with univentricular atrioventricular connection, discordant ventriculoarterial connection, and bulboventricular foramen (BVF)-dependent systemic flow. MATERIAL AND METHODS: Intraoperative transesophageal echocardiography was used in five patients with tricuspid atresia (N = 3) or double-inlet left ventricle (N = 2) with rudimentary right ventricle and BVF who were scheduled to undergo a bidirectional cavopulmonary anastomosis (N = 3) or completion of the Fontan procedure after previous banding of the pulmonary artery (N = 2). The BVF diameter was measured in two orthogonal views, and the area was calculated by using the formula for an ellipse. Left ventricular posterior wall thickness and left ventricular internal diameter were also measured. Intraoperative prerepair and postrepair gradients across the BVF were measured by echocardiography. RESULTS: Volume unloading of the left ventricle resulted in instantaneous contraction of left ventricular size (decrease of median left ventricular internal diameter from 38 to 34 mm and increase of median left ventricular posterior wall thickness from 5 to 7 mm), decrease of median BVF area index (from 1.82 to 1.55 cm2/m2), and development of a median gradient of 60 mm Hg across the BVF. At a mean follow-up of 19.6 months, all patients were clinically well and had no echocardiographic evidence of BVF obstruction. CONCLUSION: In hearts with univentricular atrioventricular connection, discordant ventriculoarterial connection, and BVF-dependent systemic flow, a decrease in ventricular volume is associated with an instantaneous alteration in ventricular geometry, diminution in BVF size, and potential for subaortic outflow obstruction. Intraoperative transesophageal echocardiography is of paramount importance in excluding development of subaortic outflow obstruction in this setting.

Detrimental sequelae on the wall of the internal mammary artery caused by hydrostatic dilation with diluted papaverine solution.

We studied the effect of hydrostatic dilation of the internal mammary artery used for coronary revascularization in 10 patients (aged 45 to 79 years, median 63 years). Diluted papaverine solution was injected in the lumen of distal segments of the internal mammary artery, the musculophrenic artery, or the superior epigastric artery that had been obtained at operation; injection was followed by hydrostatic dilation not exceeding a sheer force of 50 gm. In 12 control patients (aged 42 to 76 years, median 64 years) in whom the internal mammary artery had also been harvested for elective myocardial revascularization, similar arterial segments were wrapped in sponges soaked in papaverine solution of the same dilution. In the nondilated group the median (with interquartile range) number of fenestrations in the internal elastic lamina increased from the elastic (21, 7) to the elastomuscular (41, 11) and muscular segments (89, 12) (elastic-elastomuscular: p = 0.006; elastic-muscular: p = 0.006; elastomuscular-muscular: p = 0.003) (Wilcoxon signed-rank test). In none of the three histologic segments were full-thickness disruptions of the intima and disruptions of the internal elastic lamina seen. Similarly, in the dilated group the number of fenestrations in the internal elastic lamina increased from the elastic (25, 18) to the elastomuscular (43, 9) and muscular (100, 13) segments (p values 0.01, 0.01, and 0.006, respectively). In addition, in 20% of the elastic sections, in 17% of the elastomuscular sections, and in 35% of the muscular sections of the dilated group, disruptions of the intima and internal elastic lamina were seen. Comparison of the number of fenestrations in internal elastic lamina in the three histologic segments between the nondilated and dilated groups revealed a significantly greater value in the muscular segments of the latter group (p = 0.01) (Mann-Whitney U test). We concluded that (1) hydrostatic dilation of the internal mammary, musculophrenic, and superior epigastric arteries may have detrimental effects on the histologic characteristics of the intima and the internal elastic lamina and (2) the number of fenestrations in the internal elastic lamina of these arteries is related to the presence or absence of elastic lamellae in the media.

Pathology of coronary arteries, myocardium, and great arteries in supravalvular aortic stenosis. Report of five cases with implications for surgical treatment.

Among five patients with supravalvular aortic stenosis in whom autopsy tissues were available, all were male, 1 1/2 to 39 years old (mean 10 years, median 3 years), and the four children had Williams-Beuren syndrome (two familial, two sporadic). Medial thickening and dysplasia (disorganization) characterized the aortic sinotubular junction of three patients with discrete disease and the entire ascending aorta and arch branches of the two with diffuse disease. Medial dysplasia also involved the pulmonary arteries in each case, but less severely than the aorta. Dysplasia of coronary arteries was observed in all five hearts and was more obstructive proximally than distally, in cases with diffuse than discrete aortic disease, and in the adult than in the two children with discrete supravalvular aortic stenosis. All major epicardial arteries were involved, without predilection for any particular vessel. In contrast to the great arteries, coronary artery dysplasia involved all three layers, not just the media. To varying degrees, vessels showed intimal hyperplasia, fibrosis, and disorganization (dysplasia); disruption and loss of the internal elastic membrane, with indistinct intimal-medial junctions; medial hypertrophy and dysplasia; and adventitial fibroelastosis. In severe cases, the microscopic structure resembled that of the ductus arteriosus. Acute intramedial dissections were observed in the ascending aorta and distal right coronary artery in one patient each. Chronic microfocal ischemic fibrosis was identified in the subendocardium and papillary muscles of the left ventricle in four patients, and the adult patient also had an acute myocardial infarction. In summary, these findings emphasize the extraaortic extent of supravalvular aortic stenosis and the development of ischemic heart disease even in childhood. The presence of severe coronary obstruction in the adult with discrete aortic disease suggests that chronic high pulsatile coronary blood pressure may favor the proliferation of dysplastic tissue. Early surgical intervention may minimize the degree of proliferation, as well as allow regression of left ventricular hypertrophy, thereby lessening the risk of myocardial ischemia and aortic dissection.

Use of internal mammary artery in myocardial revascularization after mediastinal irradiation.

Ten patients with radiation-associated proximal coronary artery disease underwent myocardial revascularization. In seven patients (group A) the internal mammary artery was used and in the other three (group B) only venous conduits were used. Except for mild adhesions between the pericardium and the epicardium, no unusual technical problems were encountered. In all patients in group A the internal mammary artery exhibited excellent flow, and histologic examination in two patients revealed a normal intima and media with only slight fibrosis of the adventitia. In two patients in group B, fibrosis of the internal mammary artery precluded its use, whereas the third patient had contraindications prohibiting use of the internal mammary artery. Long-term follow-up (range 6 to 72 months) revealed that one patient in group A died late of metastatic disease, and of the remainder (nine patients), seven were in New York Heart Association class I and two were in class II. Preoperative assessment of the internal mammary artery by angiography or, alternatively, B-mode imaging with Doppler spectrum analysis is recommended in patients with radiation-induced coronary artery disease who are scheduled to undergo myocardial revascularization with intended use of the internal mammary artery. In our experience, despite previous exposure to irradiation, the internal mammary artery should still be considered as a viable conduit for myocardial revascularization when preoperative assessment shows patency.

In vitro comparison of bileaflet aortic heart valve prostheses. St. Jude Medical, CarboMedics, modified Edwards-Duromedics, and Sorin-Bicarbon valves.

The hydrodynamic performance of four currently used bileaflet heart valve prostheses (St. Jude Medical, CarboMedics, modified Edwards-Duromedics, and Sorin-Bicarbon) with a nominal tissue anulus diameter of 27 mm were measured in the aortic position. All experiments were performed in nonpulsatile flow and in an electrohydraulic, computer-controlled pulse duplicator simulating the left side of the human circulatory system. Testing conditions were set at cardiac outputs of 3.0, 4.5, 6.5, and 8.0 L/min at a constant heart rate of 70 beats/min. The Sorin-Bicarbon valve had the lowest pressure difference with regard to nonpulsatile (mean 5.4 mm Hg at 30 L/min) and pulsatile (mean 2.2 mm Hg at 8 L/min) flow, followed by the St. Jude Medical, CarboMedics, and modified Edwards-Duromedics valves. The leakage volumes under static and pulsatile flow conditions were lowest for the modified Edwards-Duromedics and Sorin-Bicarbon valves. The energy loss in pulsatile flow was lowest for the Sorin-Bicarbon valve, mainly because its systolic, closure, and leakage energy losses were low. Systolic sequential velocity profiles showed the most even flow distribution pattern for the St. Jude Medical and Sorin-Bicarbon valves. These findings correspond with lower overall Reynolds shear stress levels for the St. Jude Medical and the Sorin-Bicarbon valves than for the modified Edwards-Duromedics and CarboMedics valves.

Regression of tricuspid regurgitation after two-stage arterial switch operation for failing systemic ventricle after atrial inversion operation.

The cases of five patients with previous Senning (n = 4) or Mustard (n = 1) operations and failing systemic ventricles in whom banding of the pulmonary artery was performed as an interim step toward an arterial switch procedure are reported. The rise in the ratio of left to right mean systolic ventricular pressure, from 0.35 before operation to 0.90 during operation and 0.80 on the first postoperative day, caused a shift of the ventricular septum from a leftward to a midline or nearly midline position. This shift was associated with a reduction of tricuspid regurgitation. At a median interval of 5.1 months after pulmonary artery banding, the mean left ventricular posterior wall thickness had increased to 8.2 mm, versus 5 mm before operation, and the mean left ventricular myocardial mass index had increased to 90 gm/m2, versus 55.6 gm/m2 before operation. After the arterial switch operation, which was performed in four patients, the tricuspid regurgitation decreased to a trivial amount (n = 1) or disappeared completely (n = 3).

Traumatic tricuspid valve insufficiency. Experience in thirteen patients.

From 1964 through June 1993, thirteen patients with traumatic tricuspid insufficiency were treated surgically; all were male, and the ages ranged from 17 to 64 years (median 39 years). The condition was associated with blunt chest trauma in all patients: motor vehicle accidents in twelve and an explosion of a tank of compressed air in one. The median duration between trauma and operation was 17 years (range 1 month to 37 years). Preoperatively, six patients were in sinus rhythm and seven were in atrial fibrillation. At operation, the right ventricular function appeared moderately to severely depressed in twelve patients. In twelve patients, the anterior leaflet was flail because of chordal rupture (n = 9), rupture of anterior papillary muscle (n = 3), or tear in the anterior leaflet (n = 1). In one patient, the septal leaflet was missing and in another it was retracted and adherent to the ventricular septum. In five patients the tricuspid valve was repaired and in eight it was replaced. In seven patients in the latter group, the chordae, papillary muscles, and/or tricuspid valve leaflet(s) were found to be in a contracted and atrophic state, precluding repair. No early or late deaths occurred. At follow-up extending to 26 years (median 12 years), 12 patients are in New York Heart Association class I and one patient is in class II. Nine patients were in sinus rhythm and four were in atrial fibrillation. Although our experience indicates that good functional results can still be achieved many years after the onset of traumatic tricuspid valve insufficiency, earlier diagnosis and surgical treatment should increase the feasibility of tricuspid valve insufficiency, earlier diagnosis and surgical treatment should increase the feasibility of tricuspid valve repair, prevent progressive deterioration of right ventricular function, and increase the possibility of maintaining late sinus rhythm in a greater number of patients.

Modified surgical techniques for relief of aortic obstruction in [S,L,L] hearts with rudimentary right ventricle and restrictive bulboventricular foramen.

Modified techniques of aortopulmonary anastomosis were performed in six neonates with atrioventricular and ventriculoarterial discordance [S,L,L], double-inlet left ventricle, and restrictive bulboventricular foramen area (mean index 1.10 cm2/m2) with unobstructed aortic arch (n = 3) or with hypoplasia (n = 2) or interruption (n = 1) of the aortic arch. In cases of unobstructed aortic arch, a flap of autogenous aortic tissue was used to augment the posterior aspect of the anastomosis of the main pulmonary artery to the ascending aorta, thus creating the potential for anastomotic growth; this technique is applicable regardless of the position of the ascending aorta relative to the main pulmonary artery. In case of levo-transposition of the aorta with hypoplasia or interruption of the aortic arch, a modified Norwood procedure was performed, in that the proximal ascending aorta was divided at the same level as the main pulmonary artery with subsequent homograft patch augmentation from the main pulmonary artery-ascending aorta anastomosis to the level of the proximal descending aorta; this technique avoids a spiraling incision of the aorta and therefore reduces the risk of torsion of the aortic root with its inherent risks of obstruction of the coronary circulation and aortic or pulmonary valve regurgitation. There was no early or late mortality. At a mean follow-up of 16 months, in all patients, there was unobstructed aortic outflow, as evidenced by echocardiographic absence of a significant ventricular-aortic systolic gradient (mean 4.5 +/- 4 mm Hg) and absence of distal aortic arch obstruction. There was no evidence of aortic or pulmonary valve regurgitation. The reported modified techniques provide effective relief of restrictive bulboventricular foramen and aortic obstruction in [S,L,L] hearts.

Minimally invasive port-access mitral valve surgery.

OBJECTIVES: This study evaluates the feasibility of video-assisted minimally invasive mitral valve surgery by means of the Port-Access system. The aim of the study was to minimize surgical access and to develop a video-assisted surgical technique. METHODS: The Port-Access system allows for closed chest endoluminal aortic clamping, cardioplegic arrest, and decompression of the heart. The mitral valve was either repaired (n = 28) or replaced (n = 23) in 51 patients by means of a minimally invasive approach through a right lateral minithoracotomy and under videoscopic guidance. RESULTS: Mean length of incision was 5.4 +/- 1.8 cm (range 3.8 to 8 cm). Mean duration of operation, cardiopulmonary bypass, and crossclamp time was 196 +/- 53, 133 +/- 52, and 72 +/- 27 minutes, respectively. Median intubation time was 25.5 hours (range 5 to 264 hours). Median duration of intensive care and hospital stay was 2 days (range 1 to 36 days) and 13 days (10 to 36 days), respectively. Hospital mortality was 9.8% (5/51). Overall morbidity was relatively high. In two patients acute retrograde aortic dissection led to conversion of the procedure. At follow-up (261 +/- 13 days), three patients required reoperation for paravalvular leakage. Baseline mean Duke activity index score was 19.3 +/- 11.3 before the operation and increased to 23.2 +/- 10 at 6 weeks' and 24.2 +/- 10.3 at 12 weeks' follow-up, respectively. CONCLUSION: The Port-Access system allows for video-assisted minimally invasive replacement and complex repair of the mitral valve through a right lateral minithoracotomy. However, morbidity and mortality associated with this novel technique were high.

Aortic root reconstruction with preservation of native aortic valve and sinuses in aortic root dilatation with aortic regurgitation.

BACKGROUND: We assessed the results of a modified technique for aortic root reconstruction including preservation of the native aortic valve and sinuses. METHODS: A modified technique for reconstruction of the aortic root was devised in which the native aortic sinuses are preserved and remodeled, the diameter of the sinotubular junction is reduced, the ventriculoaortic junction is reinforced with a Dacron prosthesis, and the coronary ostia are reimplanted. Since January 1995, this modified operative technique was performed in 13 patients with a mean age of 54 +/- 21 years. The median grade of aortic regurgitation was 3; in 10 patients it was caused by dilatation of the sinotubular junction, and 3 had additional annuloaortic ectasia. RESULTS: The aortic crossclamping time was 61 +/- 18 minutes. In-hospital mortality was 2 of 13 (15. 3%) patients, both deaths being related to complications of aortic dissection. In 1 patient aortic regurgitation increased to grade 3, necessitating aortic valve replacement. At a mean follow-up of 2.1 years, the remaining 10 patients had stable aortic valve function with a median grade of regurgitation of 1. The mean New York Heart Association functional class was 1.2. CONCLUSIONS: Aortic root reconstruction with preservation of the native aortic valve and sinuses allows symmetric reconstruction of the aortic sinuses and adaptation of the diameters of the sinotubular and ventriculoaortic junctions, thus optimizing aortic valve function. Moreover, it prevents contact of the aortic valve leaflets with the Dacron graft, which may enhance the durability of the repair.

Comparative anatomic studies of various arterial conduits for myocardial revascularization.

Comparison was made between the morphologic condition of the left anterior descending artery and four arterial conduits: the internal mammary, right gastroepiploic, inferior epigastric, and radial arteries, harvested from 17 patients (aged 15 to 85 years, mean 64 years) who had died of nonvascular diseases. Proximal, mid, and distal segments were examined microscopically. The internal mammary artery was elastic, but the others were muscular. In all four conduits, atherosclerosis was absent to mild, the internal elastic lamina showed only minimal defects, and the vasa vasorum were confined to the adventitia. In all cases the left anterior descending artery showed mild to severe atherosclerosis and substantial defects in the internal elastic lamina with penetration of the vasa vasorum into the media and intima. Comparison of the mean distance (+/- standard deviation) from the lumen to the outermost portion of the media for the left anterior descending artery (320 +/- 63 microns) with the four conduits gave comparable values for the internal mammary artery (350 +/- 92 microns); p = not significant) and the right gastroepiploic artery (291 +/- 109 microns; p = not significant), versus 529 +/- 52 microns; p less than 0.002) for the radial artery and 249 microns (+/- 87 microns) (p less than 0.04) for the inferior epigastric artery (Kruskal-Wallis and Mann-Whitney U tests). The relatively scanty presence of smooth muscle cells in the thin-walled media of the internal mammary artery combined with a well-formed internal elastic lamina, even at advanced age, may be an important cause for its low susceptibility to atherosclerosis and a major determinant in its superior long-term patency as a coronary artery bypass graft. This finding emphasizes the justification of continued use of the ideally matching internal mammary artery, either as in situ or free graft, in coronary artery bypass grafting. In contrast to the thick-walled radial artery, which may be relatively prone to ischemia, an acceptable long-term patency of the inferior epigastric artery and right gastroepiploic artery, if harvested as pedicled grafts, is anticipated.

Retrograde versus antegrade delivery of cardioplegic solution in myocardial revascularization. A clinical trial in patients with three-vessel coronary artery disease who underwent myocardial revascularization with extensive use of the internal mammary artery.

The effects of retrograde and antegrade delivery of cardioplegic solution on myocardial function were evaluated and compared in 60 patients who underwent myocardial revascularization. All patients had three-vessel coronary artery disease, and the revascularization was done with extensive use of the internal mammary artery. Seventy-five percent of the distal anastomoses were performed with the internal mammary artery. Myocardial protection consisted of St. Thomas' Hospital cardioplegic solution, topical slushed ice, and systemic hypothermia (28 degrees C). The patients were randomly separated into two groups: group A (n = 30), who received antegrade cardioplegia, and group B (n = 30), who received retrograde cardioplegia. With the exception of the total dose of cardioplegic solution (p = 0.02), there was no significant difference between the two groups that concerned septal myocardial temperature at the moment of asystole and after infusion of the total dose of cardioplegic solution. Cardiac function was assessed before and after the patient was weaned from cardiopulmonary bypass. In the immediate postoperative period there was a significant increase in right atrial pressure of the patients who underwent antegrade cardioplegia. For the other registered parameters there was no significant difference either in the immediate postoperative period or 6 hours later. Release of creatine kinase MB isoenzyme was the same in the two groups. Clinical outcome in terms of mortality, prevalence of perioperative infarction, prevalence of low cardiac output, and rhythm and conduction disturbances was similar in both groups. Technical problems related to cannulation and decannulation of the coronary sinus were not encountered. Multivariate analysis showed that occlusion of the left anterior descending coronary artery (p = 0.012) is an essential contraindication of antegrade delivery of cardioplegic solution. Analysis of the patients with an occlusion of the left anterior descending coronary artery who underwent antegrade (n = 9) and retrograde (n = 10) cardioplegia showed a significant difference in the total dose of cardioplegic solution (p = 0.02) and septal myocardial temperature at the moment of asystole (p = 0.008) and after infusion of the total dose of cardioplegic solution (p = 0.015). The mean arterial systolic blood pressure in the antegrade group was significantly lower than in the retrograde group (p = 0.003). Preservation of the left ventricular stroke work index was significantly better in the retrograde group (namely, 85% of its initial value versus 71% in the antegrade group, p = 0.0116).(ABSTRACT TRUNCATED AT 400 WORDS)