Urs Niederhäuser

Paravalvular leakage after mitral valve replacement: improved long-term survival with aggressive surgery?

BACKGROUND Following mitral valve replacement, surgical closure of paravalvular leaks is usually advised in severely symptomatic patients and in those requiring blood transfusions for persisting haemolysis. However, the long-term prognosis of less symptomatic patients or those not needing blood transfusions is unknown. METHODS Between 1987 and 1997, we observed 96 patients with mitral paravalvular leakage. A paraprosthetic leak was diagnosed after a median time of 119 days (range: 1 day-23 years) after primary mitral valve replacement. During an average follow-up of 5 years (range: 1-23 years), 50/96 patients were referred for surgical closure. RESULTS Compared with patients who received conservative treatment, those referred for surgery had a significantly lower mean preoperative haematocrit (P = 0.002) with a higher proportion of patients being in the NYHA class III/IV (P = 0.03). Age, gender, left ventricular function and number and size of leaks did not differ between the groups. The 30-day postoperative mortality for valve reoperation was 6% (3/50); during follow-up three further patients died, resulting in an overall mortality rate of 12%. In the group treated conservatively there was a mortality rate of 26% (12/46). Thus, the actuarial survival for patients referred for surgery was 98, 90 and 88% after 1, 5 and 10 years, compared with 90, 75 and 68% for patients treated conservatively (long-rank P = 0.03). In addition, there was a significant increase in mean haematocrit levels (P = 0.0001) and an improvement in NYHA class III/IV symptoms (P = 0.002), vertigo (P = 0.001) and fatigue (P = 0.001) after surgery. CONCLUSIONS Following mitral valve replacement, a more aggressive surgical treatment is recommended for patients with paraprosthetic leaks. Surgery should be offered to less symptomatic patients, as well as those not requiring blood transfusion.

Aortic valve preservation in acute type A dissection: is it sound?

A series of 200 consecutive patients with acute Stanford type A dissection (157 men, 78%; 43 women, 22%) was analyzed to assess the validity of aortic valve preservation or repair. Indication for the operation in most cases was based on echocardiographic examination alone, to reduce the delay. In the majority of patients (111/200, 56%) the aortic valve was preserved or repaired if necessary. Aortic root replacement with a composite graft was performed in 66 of 200 patients (33%), mainly because of an enlarged aortic anulus and sinus. Replacement of the aortic valve and the supracoronary ascending aorta was performed in 23 of 200 patients (12%) with a diseased aortic valve (e.g., bicuspid valve) but an acceptable aortic sinus. Follow-up totaled 656 patient-years (maximum 14 years). Actuarial analyses as a function of type of repair and type of aortic valve provided the following probabilities plus or minus errors (95%): overall survival of the 200 patients was 78.3% +/- 2.9% after 30 days, 74.95% +/- 3.1% after 1 year, 67.9% +/- 3.6% after 5 years, and 48.5% +/- 6.1% after 10 years. Actuarial probability of freedom from reoperation for valve failure in the complete series was calculated as 100.0% +/- 0.0% after 30 days, 99.3% +/- 0.7% after 1 year, 97.5% +/- 1.5% after 5 years, and 95.1% +/- 2.8% after 10 years. During long-term follow-up, there was no significant difference among groups with regard to structural deterioration, valve thrombosis, thromboembolic complications, anticoagulant-induced hemorrhage, and endocarditis. Freedom from valve failure and valve-related complications are similar for preserved, repaired, mechanical, and biologic valves. Valve-related reoperations are rare during at least 5 years of follow-up. Hence preservation or repair of the aortic valve can be recommended in the majority of patients with acute type A dissection.

Eradication of Aortic Infections With the Use of Cryopreserved Arterial Homografts

BACKGROUND The surgical treatment of vascular infection is associated with a substantial early and late mortality. Cryopreserved homografts were evaluated for in situ reconstruction in aortic infections. METHODS Between January 1991 and July 1995, homografts were used in 19 patients (mean age, 61 +/- 13 years; range, 40-85 years) with mycotic aneurysms (9/19; 47%) or infected grafts (10/19; 53%) in the thoracic (7/19; 37%) or abdominal (12/19; 63%) aorta. Sepsis was present preoperatively in 14 of 19 (74%) patients, and 18 of 19 (95%) had received antibiotic treatment for 6.4 +/- 6 months (range, 1-36 months). Up to ten previous vascular procedures had been done in 11 of 19 patients (58%). RESULTS There was one (5.2%) early and two (11%) late deaths, with one (5.5%) of the late deaths being homograft related. The mean hospital stay was 27 +/- 26 days (range, 7-84 days). Antibiotics were given postoperatively for 30 +/- 12 days (range, 4-84 days). During the follow-up period of 18.6 +/- 13 months (range, 7-60 months), there were no instances of reinfection, suture line rupture, homograft stenosis, or anastomotic aneurysms. CONCLUSIONS Cryopreserved arterial homografts allow safe in situ reconstruction, decrease early and midterm mortality, and reduce antibiotic requirements. Early and midterm reoperations are unnecessary.

Explanted cryopreserved allografts: a morphological and immunohistochemical comparison between arterial allografts and allograft heart valves from infants and adults

OBJECTIVE Life expectancy of cryopreserved allografts implanted in infants is different from those implanted in adults. A morphological study of explanted allograft heart valves was performed to determine the mechanism of deterioration and to compare cryopreserved arterial and heart valve allografts from adult patients with those explanted from infants. METHOD Between 1987 and 1996, 209 cryopreserved allografts were implanted: 125 valved conduits or monocusps to reconstruct the right ventricular outflow tract in congenital heart disease, 50 allograft heart valves to treat native aortic and prosthetic aortic valve endocarditis and 34 cryopreserved arterial allografts to replace mycotic aortic aneurysms or infected aortic prosthetic grafts. Two months to 8 years after implantation, 23 heart valve allografts, 11 right-sided and 12 left-sided, and four arterial allografts had to be explanted for reasons such as degeneration, recurrent infection, aneurysm formation or rupture. Besides conventional staining, immunohistochemical detection of cell populations was performed as follows: CD45RO, CD3 and CD43 for T lymphocytes, CD20 for B lymphocytes, CD68 for macrophages, protein S100 for Langerhans-cells, vimentin for fibroblasts, alpha-actin for smooth muscle cells and factor VIII for endothelial cells. RESULTS Explanted cryopreserved allografts were all fibrotic, acellular, non-vital and without endothelial cells. The fibrous tissue was preserved. T lymphocytes, indicating rejection, were found in all right-sided allografts from the paediatric population, but only in 9% of left-sided valves explanted from adults and in one of the four of arterial allografts. Macrophages and Langerhans-cells were found only in right-sided allografts from paediatric patients. CONCLUSION Right-sided cryopreserved allografts from a paediatric population showed ongoing cellular rejection. By contrast, there was only a weak T-cell mediated rejection to adult heart valve and arterial allografts. Therefore, similar long-term results can be expected in adult arterial and heart valve allografts, whereas longevity of right-sided heart valve allograft in the paediatric age group seems endangered by cellular rejection.

Cardiac surgery in a high-risk group of patients: Is prolonged postoperative antibiotic prophylaxis effective?

OBJECTIVE In a prospective, randomized study, postoperatively prolonged antibiotic prophylaxis is evaluated in a high-risk group of patients undergoing cardiac operations. These patients had postoperative low cardiac output necessitating inotropic support and intraaortic balloon pumping. METHODS Between January 1991 and 1994, 53 patients were enrolled in the study (42 men, mean age 65 years). All patients received the usual perioperative (24 hours) cefazolin prophylaxis. In the study group (n = 28) a prolonged regimen of prophylaxis with ticarcillin/clavulanate was performed for 2 days and vancomycin was added in a low dose until removal of the intraaortic balloon pump. The control group (n = 25) did not receive a prolonged regimen of prophylaxis. Follow-up ended at hospital discharge. RESULTS Early mortality was 7 of 28 patients (25%) in the prophylaxis group and 8 of 25 patients (32%) in the control group (p = 0.397). Defined infections (pneumonia, n = 22; sepsis, n = 8; deep sternal wound infection, n = 2) occurred in 50% of the study group and 68% of the control group (p = 0.265). In all patients with septicemia, only coagulase-negative staphylococci could be isolated from the bloodstream (5 patients in the prophylaxis group vs 3 in the control group). Infectious parameters were controlled daily and did not differ significantly between groups. A total of 1158 bacteriologic tests were performed (blood cultures, n = 389; intravascular catheters, n = 208; bronchial aspirates, n = 411; intraaortic balloon pumps, n = 42; wound secretions, n = 108) showing bacterial growth in 322 (28%) without a significant difference between the groups. In the prophylaxis group, 13 intravascular catheters and intraaortic balloon pumps showed bacterial growth versus 11 in the control group. No side effects were seen. CONCLUSIONS In a high-risk group of patients undergoing cardiac operations, infectious outcome could not be effectively influenced by an additional and prolonged postoperative prophylaxis regimen with low-dose vancomycin and ticarcillin/clavulanate. Low-dose vancomycin did not reduce the rate of infections or colonizations of intravascular catheters with gram-positive organisms.

Emergency surgery for acute infective aortic valve endocarditis : performance of cryopreserved homografts and mode of failure

OBJECTIVE To describe our experience in the surgical treatment of infective, native and prosthetic aortic valve endocarditis, using cryopreserved homograft valves. METHODS Between January 1988 and September 1995, cryopreserved homografts were implanted in 49 patients (mean age 47 +/- 15 years; range 19-79) with acute infective endocarditis of the native (21/49; 43%) or the prosthetic (28/49; 57%) aortic valve. Aortic root abscesses were found in 39/49 (80%) patients, ventriculo-aortic disconnection in 27/49 (55%). An intracardiac fistula, originating from the left ventricular outflow tract was found in 25/49 (51%) patients. Indications for emergency surgery were congestive heart failure due to severe aortic valve regurgitation in 44/49 (90%) and systemic emboli in 5/49 (10%) patients. Preoperatively, 23/49 (47%) patients were in New York Heart Association (NYHA) class IV, and 5/49 (10%) were in acute circulatory failure. Mean left ventricular ejection fraction was 53 +/- 10% (25-65). Streptococci (27%) and staphylococci (27%) were the most important microorganisms found. The homograft was implanted as a scalloped freehand valve (34/49; 70%), as an intra-aortic inclusion cylinder (4/49; 6%) or as a free-standing root replacement (12/49; 24%). Combined procedures were necessary in 11/49 (22.5%) patients. RESULTS Hospital mortality was 8.2% (4/49): 2/49 (4.1%) patients died from endocarditis-related sepsis, one (2%) from low cardiac output and one (2%) from a cerebrovascular accident. After a mean interval of 21 +/- 15 months (2-48), 9/45 (20%) patients had to be reoperated, all reoperations except one being homograft related. After a mean follow-up of 35 +/- 22 months (2-90), 4/44 (9%) patients had their homograft replaced by a mechanical prosthesis. After 5 years, actuarial freedom from late death was 97 +/- 3%; from late reoperation 69 +/- 9%; from late endocarditis 85 +/- 8%; and from late homograft degeneration 87 +/- 6%. Explanted homografts were acellular and non-vital, containing bacteria and/or leucocytes. B-lymphocytes were found in all and in one, T-cell lymphocytes were present. CONCLUSION Emergency aortic valve replacement with cryopreserved homografts for acute native or prosthetic aortic valve endocarditis has a low operative mortality. The late incidence of recurrent endocarditis or homograft failure up to 7 years is acceptable. Cryopreserved homografts are non-viable. The presence of T-cell lymphocytes in explanted homografts indicates that rejection may be possible.

Aortobronchial and aortoesophageal fistulae as risk factors in surgery of descending thoracic aortic aneurysms

OBJECTIVE Assess outcome of patients with descending thoracic aortic aneurysms complicated by aortobronchial and aortoesophageal fistulae in comparison to patients undergoing repair of aortic aneurysms without fistulae. METHODS In a consecutive series of 145 patients (age 60 +/- 12 years) with repair of descending thoracic and thoracoabdominal aortic aneurysms, 11 patients (8%; age 63 +/- 9; NS) primarily presented for hematemesis and/or hemoptysis. In 8/11 patients (73%) an aortobronchial fistula was identified, and 3/11 patients (27%) suffered from an aortoesophageal fistula. Five of 11 patients (45%) had undergone previous aortic surgery in the same region. RESULTS Extent of aortic segments (range 1-8) replaced was 3.1 +/- 1.4 for all versus 2.6 +/- 0.9 for fistulae (NS). Aortic cross clamp time was 38 +/- 22 min for all versus 45 +/- 15 min for fistulae (NS). Mortality at 30 days was 18/145 (12%) for all versus 16/134 (12%) without fistulae versus 2/11 (18%) with fistulae (NS). Paraparesis and or paraplegia was observed in 11/145 (8%) for all versus 10/134 (7%) without fistulae versus 1/11 (9%) for cases with fistulae (NS). Nine additional patients died after hospital discharge, seven without fistulae and two with fistulae (days 80, and 120) bringing the 1-year mortality up to 23/134 (17%) without fistulae versus 4/11 (36%) with fistulae (NS). Further analysis shows that the 1-year mortality accounts for 1/8 patients (13%) with aorto-bronchial fistulae versus to 3/3 patients (100%) with aorto-esophageal fistulae (esophageal versus bronchial fistula: P = 0.018; esophageal versus no fistula: P = 0.006). CONCLUSIONS Outcome of patients suffering from descending thoracic aortic aneurysms complicated by aorto-bronchial fistulae can be similar to that without fistulae, whereas for cases complicated by aorto-esophageal fistulae the prognosis seems to remain poor even after successful hospital discharge.

Conservative treatment of the aortic root in acute type a dissection

OBJECTIVE In acute type A dissection long-term results of conservative aortic root surgery were compared with the outcome of primary valve and/or root replacement. METHODS Between 1985 and 1995, 199 patients (mean age 59 years, 154 men) were operated on. The aortic root was involved in the dissection process and valve incompetence of varying degree was present without exception. Replacement of a proximal aortic segment was standard procedure in all patients. The aortic valve was preserved in 126 patients: commissural suture resuspension (12 patients), root reconstruction with GRF-glue (gelatine-resorcin-formaldehyde/glutaraldehyde-glue) (114 patients). Valve replacement was performed in 73 patients (50 composite grafts, 23 valve prostheses with separate supracoronary grafts). Preoperative risk factors (valve replacement vs. preservation): coronary artery disease (11 vs. 8%, NS), tamponade (18 vs. 17%, NS), unstable hemodynamics (22 vs. 15%, NS), renal failure (4 vs. 6%, NS), neurologic disorder (19 vs. 32%, NS). RESULTS The overall early mortality was 23.6% (47/199 patients) and increased after commissural suture resuspension compared with GRF-glue reconstruction (P = NS). Parameters of the early postoperative period did not differ between conservative treatment and root/valve replacement: low cardiac output, 34 versus 38% (P = NS); myocardial infarction, 10 versus 11% (P = NS); hemorrhage, 25 versus 23% (P = NS); duration of intensive care (P = NS). Survival was 61% after 8 years without difference between the two principal treatment groups (P = NS) and between the two conservative subgroups (P = NS). At 2 years, GRF-glue reconstruction had an increased freedom from reoperation on the aortic root (92 vs. 70%, P = 0.0253) and event free survival (77 vs. 41%, P = 0.0224) compared with suture resuspension. Commissural suture resuspension was an independent, significant predictor for reoperation (P = 0.0221, relative risk = 4.7130). CONCLUSION Surgery for acute type A dissection still carries a considerable early risk. Preservation of the aortic root is safe in the absence of Marfan or annuloaortic ectasia, but a certain incidence of reoperations on the aortic valve and the aortic root has to be accepted. Root reconstruction using GRF-glue is the method of choice and is superior to suture resuspension, with a significantly better reoperation-free and event-free survival.

Embolization of biologic glue during repair of aortic dissection

A 72-year-old patient was operated on because of an acute type A aortic dissection with the primary entry located in the aortic arch and with retrograde involvement of the ascending aorta. Complete replacement of the aortic arch and the ascending aorta was performed after the dissected aortic layers had been readapted and sealed with gelatin-resorcin-formaldehyde biologic glue. Postoperative neurologic status was judged to be normal. The patient died 3 weeks postoperatively of septic shock. Postmortem examination of the brain revealed several small lesions, and microscopy showed very small particles of polymerized glue in the afferent vessels of ischemic cerebral and meningeal regions.

Surgery for ruptured thoracic and thoraco-abdominal aortic aneurysms

OBJECTIVE To assess the outcome of patients with ruptured descending thoracic and thoracoabdominal aortic aneurysms undergoing emergency repair, in comparison to elective surgery for chronic lesions. METHODS A prospective study of 100 consecutive patients operated upon the descending aorta (1-8 segments) using proximal unloading and distal protection with partial cardiopulmonary bypass, heparin surface-coated perfusion equipment and low systemic heparinization (loading dose 100 IU/kg, activated coagulation time > 180 s), staged cross-clamping, sealed grafts and graft inclusion. RESULTS Arteriosclerotic lesions were present in 53/100 patients (53%) for all, 30/53 (56%) for chronic, and 21/33 (63%) for ruptured, aneurysms (NS). Dissecting lesions were found in 38/100 patients (38%) for all, 20/53 (38%) for chronic, and 8/33 (24%) for ruptured aneurysms (NS). Preoperative hematocrit was 38 +/- 6% for all, 40 +/- 5% for chronic, and 33 +/- 5% for ruptured aneurysmal patients (P < 0.001 ruptured versus chronic). The extent of aortic repair (1-8 segments) was 3.3 +/- 1.6 for all, 3.5 +/- 1.5 for chronic, and 3.2 +/- 1.4 for ruptured, aneurysms (NS). Transdiaphragmatic repair was performed in 51/100 (51%) of all, 28/53 (53%) of chronic, and 17/33 (51%) of ruptured aneurysms (NS). Aortic cross-clamp time was 38 +/- 21 min for all, 39 +/- 24 min for chronic, and 38 +/- 17 min for ruptured, aneurysmal patients (NS). The amount of red cells washed and autotransfused was 2792 +/- 2239 ml in all, 3143 +/- 2531 ml in chronic, and 2074 +/- 1350 ml in ruptured, aneurysmal patients (P < 0.025). The amount of packed red cells required was 2181 +/- 1830 ml for all, 1736 +/- 1333 ml for chronic, and 2947 +/- 2395 ml for ruptured aneurysmal patients (P < 0.010). Thirty-day mortality was 9/100 (9%) for all, 3/53 (6%) for chronic, and 5/33 (15%) for ruptured aneurysmal patients (NS). Parapareses/plegias occurred in 9/100 (9%) of all, 6/53 (11%) of chronic, and 3/33 (9%) of ruptured, aneurysmal patients (NS). Stepwise regression analysis identified aortic cross-clamp time as a predictor of early mortality (P = 0.002) and parapareses and paraplegias (P = 0.001). Age (P = 0.001), extent of repair (P = 0.008) and preoperative hematocrit (P = 0.001) were predictors for homologous transfusion requirements. CONCLUSION Emergency repair of ruptured descending thoracic and thoracoabdominal aortic aneurysms can be achieved with acceptable results.