Late increase in luminal diameter of aortocoronary venous bypass grafts associated with an increase in the vascular region under supply.

In a previous study, a significant inverse relation was found between the luminal size of aortocoronary venous bypass grafts and the vascular resistance of the coronary region that was perfused by the bypass graft in late stages after bypass surgery. This observation suggested that changes in the graft-dependent vascular area could influence the luminal size of the vein graft, even when they occurred several years after operation. Whereas it is well established today that aortocoronary vein grafts often decrease in luminal diameter after implantation, an increase in the bypass lumen has so far not been reported. Therefore, changes in luminal diameter of 27 vein grafts in 21 patients who underwent at least two postoperative angiographic studies (first study 8 +/- 5 months after surgery, second study 58 +/- 32 months after surgery) were compared with the size of the vascular region supplied by the bypass. The graft diameter was found to be unchanged between the two studies (3.3 +/- 0.6 versus 3.4 +/- 0.7 mm, p = NS) when the dependent vascular area was unchanged. A significant increase in graft diameter from 2.8 +/- 0.8 to 3.9 +/- 0.9 mm (p less than 0.001) was observed in nine patients in whom the area of perfusion had increased between the two studies because of the development of occlusion or obstruction of major coronary branches that were now perfused from the grafted vessel by way of collateral vessels. These data support the contention that the luminal size of aortocoronary vein grafts can adapt to the needs of the dependent myocardial vascular region even late after operation rather than being the result of a nonreversible degenerative process as commonly assumed.

Treatment of extensive aortic aneurysms by a new multiple-stage approach.

A new multiple-stage approach to extensive aneurysmal disease of the aorta is presented. The method is designed to obviate the proximal graft-to-aorta anastomosis in second-stage and third-stage aortic replacement to simplify and facilitate these operative steps. Since 1981 a total of 17 such procedures were performed in seven patients with dissecting and nondissecting aneurysms without deaths or complications related to the method.

Risk of replacement of descending aorta with a standardized left heart bypass technique.

Replacement of the descending aorta for aneurysms (51%) and dissection (49%) was performed in 132 patients with a highly standardized left heart vortex-pump bypass. No adjuncts other than staged aortic clamping and intercostal artery reconnection were used to reduce spinal cord injury in extensive involvement. Four patients (3%) died early, two of cardiac cause, and nine (7%) died late. Complications of vital organ function occurred in eight patients, two having reversible renal failure and six spinal cord injury that was permanent in three (2.3%). Cord injury occurred only in replacement beyond thoracic segment 8 and could not be completely avoided despite distal intercostal artery reconnection in two cases; in the other four cases such vessels either did not appear worth reconnecting or were sacrificed in emergency operations. We conclude that left heart bypass effectively unloads the proximal circulation during aortic occlusion while maintaining adequate perfusion of distal vital organs as evidenced by low rates of early mortality and renal failure. The remaining risk of spinal cord damage may be lowered by more aggressive reconnection of all distal intercostal arteries and by extending the permissible cord ischemic period by means of hypothermia.

Surgical treatment of active infective endocarditis with paravalvular involvement.

Aortic root infection remains a challenging problem in the surgical treatment of both native and prosthetic valve endocarditis. Between 1980 and 1991, 73 patients with active aortic valve endocarditis and paravalvular infection underwent operation. Indications for operation included congestive heart failure and uncontrolled sepsis. Aortic root abscesses were located in the noncoronary anulus or in the aorticomitral junction in 45% of cases, followed by the subannular interventricular septum in 23%. Two patients had an aorticoatrial fistula, seven an interventricular septal defect. Total or partial left ventricular-aortic dehiscence was observed in 27 patients. All patients underwent aortic valve replacement, nine with simultaneous mitral valve operations. Two of the latter required patch reconstruction of the destroyed aorticomitral septum with double valve replacement. Reconstruction of the aortic base was possible in 16 patients, whereas in 12 total replacement of the aortic root was necessary. In one patient, supracoronary aortic valve replacement was used. Recently, topical application of antibiotics in fibrin sealant was used in 25 patients. The operative mortality rate was 21% and correlated to preoperative uncontrolled sepsis and the presence of extensive root destruction. Operation for active endocarditis of the aortic root requires radical, individualized techniques and results in an acceptable operative and long-term risk. The use of an antibiotic fibrin compound appears to be a useful prophylactic tool to prevent postoperative residual endocarditis.

Fibrin adhesive: an important hemostatic adjunct in cardiovascular operations.

Fibrin adhesive was applied 413 times in a group of 340 patients undergoing extracorporeal circulation whenever conventional suturing appeared impossible, difficult, or dangerous, with a success rate of 95%. Fibrin-presealed woven or knitted fabric was inserted in 60 heparitized patients, 45 of whom underwent cardiac procedures. There was perfect sealing of the fabric in all but one instance. Fibrin gluing has become a routine method, reducing man-hours and blood loss and occasionally salvaging patients' lives. Fibrin-presealed knitted prostheses are expected to replace woven fabric because of its known poor healing qualities.

Surgical treatment of airway complications after lung transplantation.

The treatment of dehiscence or stenosis of the bronchus after lung transplantation has to date consisted of endobronchial stenting or balloon dilation. Operative intervention has been limited to retransplantation with all its limitations. In our series of 121 anastomoses at risk, severe bronchial stenosis occurred in 11 (9%). In five instances the airway complications were treated surgically: two patients underwent retransplantation, one patient had a bilobectomy, and two required sleeve resection of the stenotic segment. All these procedures successfully removed the stenosis. This experience demonstrates that options other than bronchial anastomotic stenting and dilation may be successfully used to overcome posttransplantation anastomotic complications. Conventional resections may result in superior long-term graft function compared with retransplantation, avoiding the immunologically adverse effects of the latter procedure.

The mechanism of spinal cord injury after simple and double aortic cross-clamping.

Ischemic spinal cord injury after cross-clamping of the descending aorta can occur independently of aortic disease. In a previous study we had shown a precipitous uniform fall of spinal surface oxygen tension downstream to the clamping site irrespective of level. In the present paper, the hemodynamic changes in the spinal and aortic collateral circulation were investigated. Pressures were measured in the proximal, distal, and excluded aortic segments (descending thoracic and lumbar aorta) as well as in the intercostal and the lumbar arterial beds. Before high aortic occlusion, pressures in the intercostal and lumbar arterial beds were lower than aortic pressure. Along with the postclamping fall in distal arterial pressure, intercostal and lumbar arterial bed pressure decreased further but remained above aortic pressure. Exclusion of the thoracic aorta by double clamping restored intercostal bed pressure almost to control, whereas exclusion of the abdominal aorta hardly affected lumbar bed pressure. We conclude that spinal collateral circulation is more highly developed in the thoracic than in the lumbar region. After aortic cross-clamping, blood tends to drain away from the spinal cord rather than supplying it longitudinally. Under clinical conditions, therefore, retrograde bleeding into the opened aorta as well as into the aorta downstream to the distal clamp should be minimized and larger vessels originating from the aorta should promptly be anastomosed to the graft.

Direct measurements of oxygen tension on the spinal cord surface of pigs after occlusion of the descending aorta.

Spinal cord injury is the most dreaded complication of operative procedures on the descending aorta. Our previous experimental study on pigs indicated that an increase in the cerebrospinal fluid pressure after aortic cross-clamping did not influence the occurrence of spinal cord injury. We therefore concluded that the cause of spinal cord injury after aortic cross-clamping is due to primary oxygen deficiency in the spinal cord distal to the occlusion site, especially in the area supplied by the artery of Adamkiewicz. The aim of the present study is to examine the primary ischemic cause of spinal cord injury after aortic cross-clamping by directly measuring the oxygen tension on the spinal cord surface in pigs. During the occlusion phase, oxygen tension decreased significantly distal to the clamping site and especially in the areas supplied by the artery of Adamkiewicz both after occlusion of the high thoracic (Group I) and the lumbar aorta (Group II). The marked decrease in oxygen tension proves that hypoxia is the primary reason for spinal cord injury. The presence of a "steal phenomenon" should be discussed.

Future horizons of lung preservation by application of a platelet-activating factor antagonist compared with current clinical standards. Euro-Collins flush perfusion versus donor core cooling.

With the introduction of platelet-activating factor antagonists, a direct inhibition of ischemia-induced reperfusion injury can be achieved by prevention of platelet activation, reduction of microvascular leakage, and platelet-activating factor-induced bronchoconstriction. At present, two preservation methods are established for clinical lung preservation: (1) donor core cooling by extracorporeal circulation and (2) pulmonary artery flush with Euro-Collins solution and prostacyclin. We compared the quality of organ preservation obtained with these methods to the application of a platelet-activating factor antagonist (WEB 2170; 0.3 mg/kg) for the donor, perfusion solution, and throughout the first 6 hours of reperfusion in combination with prostacyclin (20 ng/kg/min) and Euro-Collins solution (60 ml/kg). Eighteen heterotopic heart and orthotopic left lung transplants were performed in three groups of six dogs each after 6 hours of cold ischemia (group I, donor core cooling; group II, Euro-Collins flush and prostacyclin; group III, Euro-Collins flush, prostacyclin, and WEB 2170). Myocardial preservation was achieved with St. Thomas' Hospital solution (20 ml/kg) in all groups. After transplantation, cardiorespiratory function was assessed at an inspired oxygen fraction of 0.4. After transplantation, superior results were observed in group III, as expressed by significantly improved oxygenation, while cardiac output and pulmonary artery pressures were similar in all groups. We concluded that the use of the platelet-activating factor antagonist WEB 2170 resulted in better lung preservation than current clinical standards.

The arteria radicularis magna anterior as a decisive factor influencing spinal cord damage during aortic occlusion.

Cross-clamping of the descending aorta immediately below the subclavian artery may result in damage to the spinal cord. Despite various protective procedures, the risk of such damage cannot be entirely eliminated. In an experimental study with 47 pigs, the influence of various factors on the genesis of spinal cord damage was examined. The pigs were divided into five groups: Groups I to IV--occlusion of the descending aorta for 45 minutes; Group I--no reduction in arterial blood pressure proximal to the site of occlusion; Group II--like Group I, plus drainage of the cerebrospinal fluid; Group III--reduction in arterial blood pressure; Group IV--like Group III, plus drainage of the cerebrospinal fluid; Group V--permanent ligation of the artery of Adamkiewicz. The degree of permanent spinal cord damage was 85.7% (Groups I to IV, six animals) and 71.4% (Group V, five animals). Thus there were no significant differences among the various groups. The frequency of spinal cord damage was independent of arterial blood pressure, intracranial pressure, and intraspinal pressure. The intracranial pressure and the intraspinal pressure were significantly dependent upon the central venous pressure but were independent of the arterial blood pressure.

Bronchial circulation after experimental lung transplantation. The effect of long-term administration of prednisolone.

The effect of corticosteroids on bronchial healing after modified left lung transplantation was investigated in pigs. In groups I (n = 6) and II (n = 6), animals received cyclosporine (15 mg/kg per day) and azathioprine (2 mg/kg per day). In group II, prednisolone (1 mg/kg per day) was also administered. Bronchial blood flow was estimated at the donor carina and donor second carina with laser Doppler velocimetry and radioisotopes 7 days postoperatively; macroscopic and microscopic assessments of graft airways were performed. Bronchial blood was calculated relative to the recipient carina. In group II, bronchial blood flow at the donor carina and donor second carina was significantly higher than that of group I. Macroscopic assessment revealed more pronounced ischemic changes in group I (5 of 6 animals) than in group II (2 of 6 animals, p = not significant). Microscopically, airway samples from the donor carina revealed marked destructive changes in five of six animals in group I. In group II, only mild ischemic changes, which were limited to the respiratory epithelium, were seen. We concluded that the administration of prednisolone results in improved bronchial blood flow and decreased bronchial ischemia after lung transplantation.

Exogenous surfactant treatment before and after sixteen hours of ischemia in experimental lung transplantation.

OBJECTIVE: A syngeneic, acute, double lung transplant model in the rat was used to determine the impact of exogenous surfactant treatment on graft function after prolonged cold storage. METHODS: The donor grafts were flush perfused, preserved for 16 hours, and then reperfused for 120 minutes. Untreated lungs served as controls (group I). In group II the recipient received a 200 mg/kg dose of surfactant (CuroSurf) before reperfusion. In groups III and IV, surfactant was administered before perfusion and harvesting (III, 20 mg/kg; IV, 200 mg/kg). Serial measurements of graft pulmonary vascular resistance, alveolar-arterial oxygen difference, and compliance were obtained. Final graft assessment included weight gain and histologic study. RESULTS: Repeated-measures analysis of variance showed significant improvement of graft performance in respect to compliance, alveolar-arterial oxygen difference, and pulmonary vascular resistance in donor surfactant treatment group IV (200 mg/kg) in comparison with recipient treatment (group II) and untreated controls (group I). Reducing the donor surfactant supplementation from 200 mg/kg to 20 mg/kg (group III) improved oxygenation and lung compliance as compared with untreated controls. Grafts in groups I and II had significantly more weight gain after 2 hours of reperfusion. Recipient treatment resulted in significantly more pulmonary hemorrhage in histologic sections. CONCLUSION: Donor treatment with exogenous surfactant is advantageous for preservation of graft function after extended ischemia. Positive effects may be seen with as little as 20 mg/kg of exogenous surfactant given before donor organ perfusion.

Complications of permanent transvenous cardiac pacing.

Clinical experience with permanent transvenous pacing during a 6 year period at Hannover Medical School is presented. A total of 1,376 pacemaker operations were performed in 799 patients, with a mortality rate of 1.1 per cent. The most common complications were premature battery failure, dislocation of endocardial electrodes, infections of the generator and/or electrodes, and skin ulcerations. In our cumulative follow-up period of 1,225 years, a complication necessitating a reoperation is to be expected after an average function-time of 31 months. Including normal battery exhaustion in this calculation will make reoperation necessary every 21.9 months.

Lung transplantation in Kartagener's syndrome.

Kartagener's syndrome is associated with bronchiectasis and situs inversus and may offer an indication for lung transplantation. One case of heart and lung transplantation has been published that stresses the necessity for a modified surgical procedure creating a large single atrium to manage the situs inversus. We performed a double lung transplantation in a 46-year-old patient with this disease. No technical modifications for the different anatomic relationship were necessary; discrepancies of the bronchial lumina were easily overcome.

Functional results after lung retransplantation.

In selected cases with either acute or chronic graft failure after lung or heart-lung transplantation, retransplantation remains the only therapeutic option. Since December 1987, we have performed a total of 110 single lung, bilateral lung, and combined heart-lung transplantations in 102 patients including five early and four late retransplantations in eight patients. Early retransplantation was indicated for severe reperfusion injury after single lung transplantation (n = 2) or heart-lung transplantation (n = 1), for persistent pulmonary hypertension caused by an unrecognized aortopulmonary window (n = 1), for central airway necrosis, and for contralateral pulmonary artery bleeding after bilateral lung transplantation (n = 1). Two of these patients after single lung transplantation were bridged with extracorporeal membrane oxygenation for 9 and 11 days until single lung retransplantation. Three patients underwent late single lung retransplantation 14, 24, and 26 months after single lung transplantation (n = 2) or heart-lung transplantation (n = 1) for chronic rejection, and an additional patient was treated successfully by bilateral lung retransplantation for obliterative bronchiolitis and central airway stenosis 26 months after bilateral lung transplantation. Two patients died 19 and 140 days, respectively, after acute retransplantation because of early graft failure and progressive rejection, respectively, while the other patients were discharged from the hospital. Mortality was 22.2% in the retransplantation group versus 15.1% (11 of 73 patients) undergoing primary single lung transplantation or bilateral lung transplantation (not significant). Patient survival after retransplantation ranged between 159 and 993 days (median, 453 days). Duration of postoperative ventilation was markedly prolonged in patients who underwent retransplantation.(ABSTRACT TRUNCATED AT 250 WORDS)

Donor heart-related variables and early mortality after heart transplantation.

Impaired donor heart function after heart transplantation results in the necessity for prolonged catecholamine and ventilatory support of the patient. Subsequently the risk of multiorgan impairment, infection, and rejection will be increased. In this retrospective analysis we tried to identify donor-related risk factors in patients who died early after transplantation. Of 174 patients undergoing heart transplantation from October 1985 through October 1988, 22 (12.6%) died early. Of the total, 39 cases were evaluated retrospectively for donor-related logistic and metabolic factors. All donors were analyzed with respect to the early mortality for age, weight, height, maximum dopamine concentration, thyroid hormone levels, and the duration from brain death until explantation and ischemia. Thirty patients were survivors (group A); nine patients died early (group B). By multiple regression analysis a significant influence (group A vs group B) of donor age, dopamine support, and ischemic time on early mortality could be demonstrated, whereas donor weight and height, hormone levels of triiodothyronine and thyroxine, and duration of brain death showed no correlation. From this limited experience we conclude that use of hearts from older donors with higher catecholamine support and longer ischemic times will result in an increased early mortality. In contrast, no influence of prolonged brain death times and metabolic factors could be demonstrated.

Successful lung transplantation for posttraumatic adult respiratory distress syndrome after extracorporeal membrane oxygenation support.

A severe adult respiratory distress syndrome after bilateral lung contusion was successfully treated by extracorporeal membrane oxygenation and subsequent double-lung transplantation in a 19-year-old man. The patient is fully rehabilitated 1 year after transplantation.

Occlusion of intercostal and lumbar aortic branches using plastic plugs.

Retrograde bleeding from the orifices of intercostal and lumbar arteries during aortic surgery is usually controlled by suture placement, a procedure that is time-consuming and may result in considerable blood loss. We have devised a method of occluding these arteries using polyurethane plugs. We have experienced no instances of perforation or delayed bleeding using this technique.

Repair of flail anterior leaflets of tricuspid and mitral valves by cusp remodeling.

We present an alternative approach to extensive rupture of the chordae tendineae leading to flail anterior leaflets. Resection of the affected cusp segment, suture of the cut edges, and extensive plication of the segment of annulus devoid of leaflets abolished massive regurgitation while maintaining an adequate valve orifice.

Use of the "elephant trunk technique" in aortic surgery.

BACKGROUND: In aortic replacement, the "elephant trunk technique" uses surplus intravascular graft length to facilitate subsequent operations on the downstream aorta. This study investigates the experience with the technique since its conception by our group. METHODS: Between 1982 and 1994, 80 elephant trunks were implanted in 72 patients. In 40 cases the primary position was in the proximal descending thoracic aorta, extending an aortic arch graft. In 32 instances the elephant trunk was placed in the distal descending thoracic aorta, extending descending aortic replacement. Aortic pathology comprised aneurysms in 22 cases, chronic dissection in 47, and acute dissection in 3. Fourteen patients had Marfan's syndrome. RESULTS: There was a total of 10 early deaths, 7 of which occurred during the early experience. Subsequent downstream aortic operation was undertaken in 24 patients after a mean interval of 14 months, replacing the descending thoracic aorta in 17 cases and the thoracoabdominal portion in 7 cases. Six patients underwent third-stage procedures. Several technical modifications were developed, helping to ease placement and unfolding of the trunk. CONCLUSIONS: The elephant trunk technique greatly facilitates and at the same time reduces the risk of multiple-stage aortic replacement.