Survival after pre-hospital emergency clamshell thoracotomy for blunt cardiac rupture.

Blunt trauma causing cardiac rupture is usually fatal. We report a patient with blunt cardiac injury that suffered traumatic cardiac arrest in the pre-hospital phase of their care. A cardiac tamponade was confirmed with portable ultrasound in a brief return of circulation. The patient had a further cardiac arrest and subsequently underwent damage control emergency surgery via a clamshell thoracotomy at the scene. The tamponade was released and a clamp was applied to the identified left atrial appendage rupture, a return of circulation then occurred. He was transferred to a cardiothoracic centre where a left atrial appendage rupture was identified and closed. The patient had a complicated recovery in hospital but went on to survive neurologically intact. This is the first documented case report of a neurologically intact survivor of a pre-hospital clamshell thoracotomy for blunt trauma. Although survivors of blunt trauma who have pre-hospital thoracotomy are extremely rare it should be considered in very specific circumstances.

Mitral repair best practice: proposed standards.

OBJECTIVES: To define best practice standards for mitral valve repair surgery. DESIGN: Development of standards for process and outcome by consensus. SETTING: Multidisciplinary panel of surgeons, anaesthetists, and cardiologists with interests and expertise in caring for patients with severe mitral regurgitation. MAIN OUTCOME MEASURES: Standards for best practice were defined including the full spectrum of multidisciplinary aspects of care. RESULTS: 19 criteria for best practice were defined including recommendations on surgical training, intraoperative transoesophageal echocardiography, surgery for atrial fibrillation, audit, and cardiology and imaging issues. CONCLUSIONS: Standards for best practice in mitral valve repair were defined by multidisciplinary consensus. This study gives centres undertaking mitral valve repair an opportunity to benchmark their care against agreed standards that are challenging but achievable. Working towards these standards should act as a stimulus towards improvements in care.

Thoracofemoral bypass using spliced femoral vein with removal of an infected axillobifemoral bypass graft.

A 63-year-old male underwent emergency repair of a ruptured juxtarenal aortic aneurysm via a transabdominal approach using an aorto-bi-iliac Dacron graft. This became infected. A right axillobifemoral bypass was placed and the infected graft was removed with oversewing of the aorta. The patient was re-admitted 8 months later with an infected axillobifemoral prosthesis. We harvested both femoral veins (FV) and spliced them to perform a left thoracobifemoral bypass with simultaneous explantation of the infected graft. The patient remains well with a patent graft 20 months post-operatively.

Effectiveness of two radiofrequency ablation systems in atrial tissue.

OBJECTIVE: The efficacy of the left atrial radiofrequency ablation procedure, for the curative treatment of atrial fibrillation, is dependent upon obtaining a confluent transmural line of hyperthermic cellular death. We compare the in vitro effectiveness of obtaining transmural hyperthermic cellular death (>55 degrees C) of both the Osypka single electrode and Boston Scientific Thermaline multi-electrode radiofrequency systems. METHODS: Isolated cadaver porcine hearts were used to measure epicardial temperatures either 'central' or at the 'edge' in relation to an endocardial applied radiofrequency electrode. Reference set point was 70 degrees C, and 4-6-mm thick atrial tissue was used for all applications. 'Edge' temperatures with the Boston Scientific unit were measured whilst activating both adjacent electrodes. RESULTS: Boston Scientific: Probe temperature closely approximated the set point. 'Central' epicardial temperature was lower than probe temperature until after 40 s application (P<0.05), 55 degrees C was reached at 50 s, maximal mean temperature 63.0+/-8.9 degrees C was reached at 100 s. Epicardial 'edge' temperature remained lower than probe temperature for the entire 120 s (P<0.05). Osypka: Probe temperature tended to overshoot the set point. 'Central' epicardial temperature paralleled and occasionally exceeded probe temperature reaching 55 degrees C within 10 s, maximal mean temperature 76.3+/-12.7 degrees C was reached at 10 s and exceeded the set point thereafter. 'Edge' temperature was no different to probe temperature or 'central' epicardial temperature. The mean epicardial temperatures produced with a 65 degrees C set point was no different to that with the 70 degrees C set point, except for a lower final temperature at 60 s. CONCLUSIONS: The Boston Scientific system (70 degrees C set point) requires a minimum in vitro application of 40 s to transmurally increase 4-6 mm atrial tissue temperature above 55 degrees C, and 120-s duration per application would appear to be a reasonable clinical recommendation. The Osypka system transfers thermal energy more effectively, requiring less than 10 s in vitro to achieve a similar transmural temperature, and a 30-s application can be recommended. However, a tendency to overshoot both probe and set point temperature, suggests that a lower set point of 65 degrees C might be safer and as effective.

Biocor No- React stentless aortic valve--short-term results.

OBJECTIVES: Short-term results of the bioprosthetic Biocor No-React composite porcine stentless aortic valve (Biocor Industria e Pesquisas LTDA, Belo Horizonte, Brazil) implanted in patients in whom anticoagulation was thought to be contraindicated or expected to be non-compliant. METHODS: Retrospective review of 52 consecutive prospective patients in whom this valve was implanted, between September 1994 and May 1998. RESULTS: Average age was 44 +/- 17 years; 75% of patients were operated on for rheumatic heart disease and combined procedures were done in 40% of cases. Early mortality was 5.8%, and related to pre-operative ejection fraction ( P < 0.03), New York Heart Association (NYHA) class (P < 0.01), and bacterial endocarditis (P < 0.04). On discharge, 84% of survivors were in NYHA class I and 16% in class II. The average postoperative prosthetic valve peak gradient on echocardiography was 19.9 +/- 11 mmHg and was related to pre-operative ejection fraction and smaller valve sizes. Postoperative residual trivial or mild aortic regurgitation was seen in 19 patients (36.6%), resolved on follow-up in 10 cases, and did not correlate with structural deterioration, re-operation, mortality, or widening of the non-coronary sinus. The non-coronary aortic sinus was widened on closure, because of perceived crowding of the adjacent stentless valve commisures, in 52% of cases. This was thought to be related to the use of an oblique as opposed to transverse aortotomy. Patient survival, inclusive of operative deaths, was 88.5%, and event-free survival was 80.0% at 4 years. CONCLUSION: The short-term results of this stentless aortic valve in a young predominantly third-world population group are acceptable, and appear to be superior to the results for mechanical valves in a similar patient group. We would recommend a transverse aortotomy above the sinotubular ridge to be the more appropriate aortotomy incision when using stentless aortic valves.

Postpneumonectomy aortic arch mycotic aneurysm.

A 31-year-old woman who had undergone left pneumonectomy for a tuberculosis-destroyed left lung 3 years previously presented in respiratory distress after a pregnancy complicated by preeclampsia and aspiration pneumonia. Investigation revealed a large aortic arch aneurysm as well as a filling defect in the descending thoracic aortic lumen. Emergency aortic arch reconstruction was performed for a massive pseudoaneurysm or contained rupture filling the entire postpneumonectomy space. Pathologic and microbiological examination demonstrated Aspergillus fumigatus and active inflammation.

Prosthetic heart valves: why biological?

The replacement of heart valves only became feasible after the development of the heart-lung machine in 1953. Two groups of prosthetic heart valves were subsequently developed: biological valves that do not require anticoagulation and mechanical valves that require life-long anticoagulation with Coumadin. The incidence of heart surgery and the demographics of patients who require heart valve surgery vary worldwide; these factors influence the choice of prosthetic valve for the individual patient and are briefly reviewed. Improved biological tissue-fixation methods are also increasing the durability of biological prosthetic valves and will further favor the implantation of biological valves in the future.

Penetrating thoracic injuries: what we have learnt.

BACKGROUND: Thoracic injuries, especially cardiac, vascular, and transmediastinal injuries, are amongst the most lethal of penetrating injuries. METHOD: Our experience at Groote Schuur Hospital is reviewed, where up to 1,000 patients were admitted annually with penetrating chest wounds between 1982 and 1997. RESULTS: The approximate pre-hospital mortality was 86% with penetrating cardiac injuries, 92 % with extrapericardial vascular injuries, and 11 % with pulmonary injuries. Less than 2% of pneumothorax cases and less than 10% of haemothorax cases required surgical intervention. Thoracoscopic evacuation of retained clots was successful in the majority of the latter. Most penetrating injuries of the thoracic duct required surgical exploration. The mortality of penetrating cardiac injuries varied according to clinical presentation (moribund 52%, hypovolaemia 20% and tamponade 2-5%) and the chamber involved. Higher mortalities were associated with atrial injuries. CONCLUSIONS: The appropriate use of intercostal drains and therapeutic thoracoscopy are important considerations in penetrating non-cardiac thoracic trauma. Rapid transportation, immediate triage, open-minded use of emergency room thoracotomy, and aggressive surgical management with liberal use of sub-xiphisternal pericardial windows are important factors in improving the survival of penetrating cardiac trauma.

Ischemic mitral valve repair surgery.

BACKGROUND AND AIM OF THE STUDY: The management of concomitant moderate or severe ischemic mitral regurgitation in the presence of ischemic heart disease is important for long-term prognosis. Mitral repair by either a suture or ring annuloplasty method has been advocated, although clear superiority of either method has not been established. METHODS: Combined coronary artery bypass and mitral valve surgery for ischemic mitral incompetence was performed on 68 consecutive patients between January 1996 and December 1998. The outcome in 63 of these patients (35 females, 28 males) who underwent mitral valve repair was reviewed. RESULTS: Average patient age was 61+/-9.4 years (range: 39-81 years). Average left ventricular ejection fraction (LVEF) was 42.1%; a suture annuloplasty was used in 84% and a ring in 16%. The average number of distal anastomoses was 3.9+/-1.1 (range: 1-6) and aortic cross-clamp time was 131+/-35 min (range: 58-238 min). Operative mortality rate (<30 days or in-hospital) was 12.7% and only requirement for intra-aortic balloon pumping either before or during surgery (21%) was predictive (p<0.05). On discharge, 98.2% of patients were in NYHA class I or II. Follow up (range: 1-35 months) was complete in 95% of cases. Moderate mitral regurgitation on discharge occurred in nine patients and was not related to the type of annuloplasty. Predictive risk factors were preoperative severe mitral regurgitation (p<0.04), poor LVEF (p = 0.05), and was predictive of deterioration of NYHA class (p<0.02), progression of regurgitation (p<0.05), and poor outcome (p<0.01). Poor outcome was also related to surgeon's experience. Structural valvular deterioration occurred in 21.8% of operative survivors, and there was one reoperation and four late deaths. The survival rate (including operative deaths) at 35 months was 68.3 +/- 13.1%, and event-free survival rate (no mortality, reoperation or angina) 65.2+/-6.2%. CONCLUSIONS: The type of annuloplasty used did not influence outcome. The risk of structural mitral valve dysfunction on follow up was related to severe preoperative mitral regurgitation, poor LVEF, surgeon's experience, and was predictive of poor outcome.

High glutaraldehyde concentrations mitigate bioprosthetic root calcification in the sheep model.

BACKGROUND: Fixation at high glutaraldehyde (GA) concentrations mitigated bioprosthetic calcification in the rat model. The present study intended to verify this observation in the circulatory sheep model. METHODS: Porcine aortic roots were either fixed in 0.2%, 1.0%, or 3.0% GA. Eight roots per group were implanted in the distal aortic arch of sheep. After six weeks and six months calcification and inflammation were quantitatively and qualitatively assessed. RESULTS: By increasing the GA concentration from 0.2% to 3.0%, aortic wall calcification could be reduced by 38% after 6 weeks and 34% after 6 months of implantation (p < 0.01). Mineralization coincided with the presence of elastin although calcium was predominantly found in cell nuclei and membranes. Leaflet calcification was absent in all groups after 6 weeks but in a few leaflets presented as heterogeneous, nodular spongiosa deposits after 6 months. Overall, differences between 0.2%-, 1.0%-, and 3.0%-fixed tissue were quantitative but not qualitative regarding distribution patterns. There was no significant difference in inflammatory host reaction between all groups. CONCLUSIONS: We have shown in the circulatory sheep model that the anticalcific effect of better cross-linking seems to outweigh the intrinsic pro-calcific effect of GA accumulation in bioprosthetic aortic wall tissue.

Chordal replacement for both minimally invasive and conventional mitral valve surgery using premeasured Gore-Tex loops.

Part of the complexity of mitral valve chordal replacement with expanded polytetrafluoroethylene (ePTFE) sutures is determining the correct replacement chordal length and knotting the ePTFE suture without sliding the knot. We describe a technique of measuring the required chordal length and making a "premeasured" Gore-Tex chordal loop that abolishes problems of inadvertently altering chordal length during fixation. This improves the reproducibility of chordal replacement surgery, and can be used both via conventional and minimally invasive approaches.

Blunt cardiac rupture caused by zip gun backfire.

A 16-year-old boy who sustained right ventricular rupture after backfiring of a homemade zip gun is reported. The unusual nature of this case together with the mechanisms and management of blunt cardiac rupture are briefly discussed.

New solution for prolonged myocardial preservation for transplantation.

BACKGROUND: A solution for prolonged cold storage of the heart has been developed. The Jerusalem-Cape Town Solution (JCT) is an "intracellular" type cardioplegic solution and is formulated to (1) minimize hypothermic-induced cell swelling, (2) diminish intracellular acidosis, (3) prevent the expansion of the interstitial space during the reperfusion, (4) protect against oxygen free radical injury during early reperfusion, and (5) provide substrates for regenerating high-energy phosphates. METHODS: With a Langendorff model, rat hearts were subjected to 15 minutes of perfusion with Krebs-Henseleit, 10 minutes of cardioplegic infusion and 20 hours of cold storage (5 degrees to 6 degrees C). Hearts were reperfused for 60 minutes and hemodynamic recovery was assessed. The hearts were assigned to three groups (eight hearts in each), according to the cardioplegic solution used: group 1, JCT; group 2, Bretschneider's HTK cardioplegic solution; and group 3 University of Wisconsin cold storage solution. RESULTS: After 60 minutes of reperfusion, the recovery of the coronary artery flow in group 1 (JCT) was significantly better than in group 2, and slightly better than in group 3 (64% +/- 8.9%, 47.2% +/- 11.6%, 52.5% +/- 19.9%, mean +/- SD, respectively; group 1 versus group 2, p < 0.01). The recovery of the left ventricular developed pressure (LVDP) was significantly better in group 1 compared with group 2 and group 3 (60.2% +/- 14.5%, 41.1% +/- 12.6% and 36.5% +/- 10.1%, respectively; p < 0.01). The recovery of the heart contractility expressed by the product of LVDP and the heart rate (LVDP x heart rate) was significantly higher in group 1 than in group 2 and group 3 (47.5% +/- 3.4%, 23.6% +/- 9.6%, and 28.7% +/- 8.3%, respectively, p < 0.001). In hearts stored for 12 hours in JCT or HTK, the recovery of the heart contractility did not differ significantly (73.4% +/- 12.7% or 70.8% +/- 30.8%, respectively). Modified reperfusion aimed to improve postischemic heart recovery did not bring significant changes in cardiac mechanical function but resulted in an increase in postischemic coronary artery flow recovery in hearts reperfused with amino acid-enriched buffer. CONCLUSIONS: The JCT solution is effective (as well as HTK) in preserving the ischemic hearts for up to 12 hours. It is superior to HTK or University of Wisconsin solution at 20 hours of isolated ischemic storage.

Blunt cardiac rupture.

Cardiac rupture as a result of blunt trauma is not commonly encountered. Seven patients with this injury have been treated at Groote Schuur Hospital over the past 14 years. All presented with cardiovascular collapse and 4 developed signs of cardiac tamponade. A clinical diagnosis was made in 4 patients and echocardiography was done in 3. Pericardiocentesis was used in 1 patient to confirm the diagnosis. Significant diagnostic delay occurred in 1 patient with associated liver rupture. Two patients required emergency room thoracotomy. All other patients were approached using a median sternotomy. Five patients survived, giving an overall survival rate of 71%. Five patients had right atrial ruptures and 2 right ventricular ruptures. One patient with right ventricular rupture died in the operating room, while another patient with multiple right atrial ruptures died from multiple organ failure after 11 days. We also briefly review the history, mechanisms and pathology.

Tissue adhesives in cardiovascular surgery.

Tissue adhesives are increasingly being used in cardiovascular surgery as adjuncts to obtain more rapid hemostasis, as tissue reinforcing agents, as carriers for prolonged local release of antibiotics, to spatially fix long saphenous vein grafts that could otherwise possibly kink, and to promote endothelialization of prosthetic graft surfaces. The available tissue adhesives, their current indications for use, and possible future trends are discussed.

Improved ultrastructural preservation of bioprosthetic tissue.

BACKGROUND AND AIMS OF THE STUDY: Poor ultrastructural tissue preservation of bioprosthetic heart valves is associated with a higher propensity for calcification. In spite of this realization, commercial valve fixation remains suboptimal. METHODS: In an attempt to maintain tissue integrity through improved cross-linking procedures, transmission electron microscopy and a 21-point damage score were applied to assess the ultrastructural preservation of aortic wall tissue-the main component of contemporary aortic valve bioprostheses. An ideal glutaraldehyde (GA) concentration was assessed by immediate tissue fixation at 4 degrees C comparing 0.2%, 0.5%, 0.65%, 1.0%, 2.0%, 3.0% and 4.0% GA in phosphate-buffered saline (PBS). Subsequently, an optimal concentration of 3.0% GA was used to determine the effect of fixation temperature (4 degrees, 22 degrees and 37 degrees C). Finally, the superior glutaraldehyde concentration (3.0%) and cross-linking temperature (4 degrees C) were used to assess tolerance towards delayed fixation. RESULTS: When different GA concentrations were used almost identical damage scores of 6.3 and 5.8 were found for 0.2% and 0.65% fixation. The first significant improvement was found at a concentration of 1.0% (score 3.3; p < 0.01) followed by a further improvement at 3.0% (score 2.6; p = 0.05). The optimal fixation temperature was 4 degrees C (3.7) with the worst results obtained at room temperature (score 9.2; p < 0.03). When fixation was delayed, the most significant damage occurred during the initial 30 min after slaughter (from 2.3 to 7.4; p < 0.02) followed by another significant deterioration between 4 and 16 h (from 5.6 to 9.7; p < 0.02). CONCLUSIONS: In summary, the prerequisites for an ideal ultrastructural preservation of bioprosthetic aortic wall tissue are immediate fixation (within 30 min), high GA concentrations (> 1.0%) and cold-temperature fixation (4 degrees C).

High glutaraldehyde concentrations reduce rather than increase the calcification of aortic wall tissue.

BACKGROUND AND AIMS OF THE STUDY: This study was performed in order to: (i) determine whether a similar reduction of tissue calcification as seen after prolonged storage can be achieved through higher concentrations of glutaraldehyde (GA); and (ii) verify that well-preserved tissue integrity can suppress calcification. METHODS: Before fixation in 0.2% GA (PBS, 4 degrees C, seven days) porcine aortas were kept on ice for 48 h. Alternatively, tissue was immediately fixed at the abattoir in 0.2%, 1.0% or 3% glutaraldehyde (PBS, 4 degrees C, seven days). A second group of immediately fixed tissue (0.2%, 1.0%, 3.0% GA) (PBS, 4 degrees C, two days) had an interim step of L-lysine treatment (0.1M, 37 degrees C, acetic acid buffer, two days) in order to enhance cross-linking followed by warm-temperature fixation (PBS, 37 degrees C, five days). Two animal models were compared: subcutaneous implantation in rats (12 weeks) and vascular implantation in non-human primates, Chacma baboons (six weeks). RESULTS: In both animal models the highest level of calcification was found in the group with delayed fixation in 0.2% GA. In the rat model there was an inverse correlation between tissue calcification and the GA concentration used, with 3% GA-fixed tissue showing the lowest level of tissue calcium. Overall, increasing GA concentration had a significant benefit on calcification (p < 0.0001; two-factor analysis of variance). Enhancement of cross-linking with L-lysine further abrogated tissue calcium levels at all GA concentrations (p < 0.0001; two- factor analysis of variance). Although the short-term baboon model showed lower tissue calcium levels, the trend seen in the rat model was confirmed. CONCLUSIONS: Our results demonstrate the detrimental effect of delayed fixation and further suggest that, against previous beliefs, fixation at higher glutaraldehyde concentrations reduces the calcification tendency of cross-linked aortic tissue.

Glutaraldehyde detoxification of aortic wall tissue: a promising perspective for emerging bioprosthetic valve concepts.

BACKGROUND AND AIMS OF THE STUDY: Due to its superb crosslinking activity, glutaraldehyde (GA) is still the most widely used fixative for bioprosthetic heart valves. At the same time, however, GA is also believed to be partly responsible for tissue calcification and the lack of surface re-endothelialization, both of which may contribute to valve degeneration. Although excess GA has previously been extracted from thin leaflet tissue, this treatment proved insufficient for the detoxification of thick aortic wall tissue of stentless valves or root prostheses. METHODS: In order to establish a detoxification procedure which thoroughly extracts biologically active GA from aortic wall tissue, we used a highly sensitive bioassay where endothelial cells were seeded onto glutaraldehyde-fixed aortic wall discs following various detoxification procedures. Absolute cell numbers and morphologic shape were correlated with shrinkage temperature and shrinkage extent of the tissue to determine the potential of the treatments to reverse crosslinks. To optimize treatment conditions, pH (3.2 versus 4.5), temperature (22 degrees C versus 37 degrees C) and incubation time (48 h versus one week) were varied. In order to identify an optimal detoxification agent, 12 different amino-reagents from four chemical groups were compared: low pKa aromatic amines, amino acids, low pKa N-heterocyclic compounds and amino sugars. RESULTS: Amino-reagent treatment required warm temperature (37 degrees C), prolonged reaction time (one week) and a pH of 4.5 to achieve long-term cell growth on glutaraldehyde-fixed aortic wall. All 12 amino-reagents were able to detoxify aortic tissue satisfactorily; and all mildly reversed crosslinks, although there were differences between candidates. When summarized data were ranked correlating cell growth and quality with shrinkage temperature and shrinkage extent, seven reagents had a rank sum above the overall mean value, and five below with statistically significant differences between candidates. The additional stabilization of the detoxification reaction through borohydride-reduction had no further effect on tissue biocompatibility and crosslinks. CONCLUSIONS: Efficient detoxification of thick aortic wall tissue is possible if a one-week incubation in an acetic acid buffer-based amino-reagent is carried out at 37 degrees C.