CT appearance of complications related to thoracic endovascular aortic repair (TEVAR): a pictorial essay.

Thoracic endovascular aortic repair (TEVAR) is a recognized treatment for various diseases involving the thoracic aorta. Patients treated with TEVAR require lifelong surveillance for potential complications, with CT being highly utilized in most centres. Endoleak is the most common complication and can be detected using CT. However, other complications such as stent strut perforations and end organ ischemia can also be detected on CT. The purpose of this pictorial essay is to illustrate the CT appearance of post-TEVAR complications encountered in our institution and to highlight their significance.

Beyond Ortner's syndrome--unusual pulmonary complications of the giant left atrium.

INTRODUCTION: The giant left atrium (GLA) is a complication of severe mitral valve disease and causes morbidity by compressing adjacent intra-thoracic structures. CLINICAL PICTURE: We report 2 cases of unusual pulmonary complications of the GLA. Case 1 developed recurrent collapse of the left lung due to left main bronchus compression. Case 2 was diagnosed with right middle lobe compression and collapse. TREATMENT AND OUTCOME: Case 1 was successfully treated by mitral valve replacement and left atrial reduction surgery. Case 2 was treated conservatively. CONCLUSION: Pulmonary atelectasis may occur in patients with GLA due to bronchopulmonary compression. Surgical management with valve replacement and atrial reduction may be necessary to relieve airway compression.

Early and late survival after surgical treatment of culture-positive active endocarditis.

OBJECTIVE: To describe a 30-year experience with surgically treated culture-positive active endocarditis. DESIGN: We retrospectively reviewed the microbiologic, clinical, and operative findings and the survival data in 151 patients with culture-positive active endocarditis encountered between 1961 and 1991. RESULTS: The mean age of the 110 male and 41 female patients was 49.8 years. Native valve endocarditis was present in 86 patients, and prosthetic valve endocarditis (PVE) was diagnosed in 65. The aortic valve was involved in 62% of patients, the mitral valve in 25%, and both valves in 10%. The operative mortality was 26%. The most important univariate determinants of mortality were an abscess at operation (P = 0.01) and renal failure (P = 0.03). A trend toward a higher mortality with PVE and staphylococcal infection was noted. For hospital survivors, the 5- and 10-year survival was 71% and 60%, respectively. Univariate determinants of an adverse long-term survival were annular abscess (P = 0.01), renal impairment (P = 0.01), heart failure (P = 0.02), and aortic valve involvement (P = 0.05). On multivariate analysis, the most important adverse determinants of long-term survival were heart failure (P = 0.02), renal impairment (P = 0.02), and PVE (P = 0.03). Thirty patients required a subsequent reoperation; of these, seven required a second and two a third operation. The most common reason for reoperation was periprosthetic regurgitation without infection (N = 19). Four operations were performed for recurrent endocarditis. At 5 and 10 years, the risk of reoperation was 23% and 36%, respectively. CONCLUSION: Although surgical treatment of culture-positive active endocarditis is still associated with substantial mortality, the long-term outcome of hospital survivors is excellent. Subsequent reoperations for periprosthetic leak are common, but recurrent infection is uncommon.

Exogenous hyaluronidase induces release of nitric oxide from the coronary endothelium.

OBJECTIVE: Hyaluronidase, an endogenous enzyme that hydrolyzes mucopolysaccharides, has been shown to enhance myocardial protection when added to preservation solutions. In addition, hyaluronidase infusion reduces injury to ischemic myocardium. Endothelium-derived nitric oxide is an endogenous vasodilator that prevents leukocyte adhesion to the intima and inhibits platelet adhesion and aggregation in the coronary artery. Experiments were undertaken to determine whether the protective action of hyaluronidase could be mediated by the endogenous release of nitric oxide. METHODS: Segments of coronary artery, with and without endothelium, were placed in organ chambers (25 mL) to measure isometric force. Blood vessel segments were contracted with prostaglandin F(2)(alpha) (2 x 10(-6) mol/L) and exposed to hyaluronidase (3-15 units). RESULTS: Hyaluronidase induced vasodilation of arteries with intact endothelium but not of arteries without endothelium (n = 6, P<.05). Endothelium-dependent vasodilation to hyaluronidase was blocked by N(G)-monomethyl-L -arginine (10(-5) mol/L), an inhibitor of nitric oxide synthesis from L -arginine (n = 6, P<.05). Inhibition of vasodilation by N(G)-monomethyl-L -arginine was reversed by L -arginine (10(-4) mol/L) but not D -arginine (10(-4) mol/L; n = 6, each group). Vasodilation to hyaluronidase also was inhibited by hemoglobin (2 x 10(-6) mol/L), a scavenger of the nitric oxide radical (n = 6, P<.05). CONCLUSIONS: Hyaluronidase induces the release of nitric oxide from the coronary endothelium. Because nitric oxide, an endogenous vasodilator, inhibits leukocyte adhesion to the intima in addition to inhibiting platelet adhesion and aggregation, stimulated production of endothelium-derived nitric oxide by exogenous hyaluronidase could be the mechanism of the protective action of hyaluronidase infusion.

Outcome of mitral valve repair in patients with preoperative atrial fibrillation. Should the maze procedure be combined with mitral valvuloplasty?

To examine late outcome of mitral valve repair in patients with preoperative atrial fibrillation, we reviewed the cases of 323 consecutive patients who underwent mitral valvuloplasty for mitral regurgitation from 1980 to 1991; average age of 215 men and 108 women was 64 years (range 14 to 88 years), and 224 patients (70%) were in New York Heart Association class III or IV before operation. The main indications for operation were severe mitral regurgitation (76%), coronary artery disease with associated mitral regurgitation (15%), and aortic valve disease (6%). At the time of mitral valve repair, coronary artery bypass grafting was done in 35% of patients, aortic valve replacement was done in 7%, and multiple other procedures were done in 10%. For all patients, the 30-day mortality rate was 2.5% (70% confidence limits 1.6% to 3.4%) and survivorships at 3 and 5 years were 81% and 76%, respectively. Before operation, 216 patients were in sinus rhythm and 97 patients had atrial fibrillation; in the latter group, 11 had recent onset of atrial fibrillation within 3 months preceding mitral valve repair. Comparing patients with preoperative atrial fibrillation to those with sinus rhythm, we found no significant difference in operative mortality (3% versus 1.9%) or 5-year survivorship (74.3% +/- 6.3% versus 76.9% +/- 4.0%). At late follow-up, atrial fibrillation was present in 5% of patients with preoperative sinus rhythm, 80% of patients with preoperative chronic atrial fibrillation, and 0% of patients with preoperative recent onset atrial fibrillation (p < 0.01). The left atrial size by echocardiography was larger in patients with preoperative atrial fibrillation compared with that in those with sinus rhythm (59 +/- 1.4 mm versus 50.9 +/- 0.7 mm; p < 0.05). There was, however, only a weak correlation between preoperative left atrial size and late atrial fibrillation. Further, age, gender, and associated coronary artery disease did not correlate with presence of atrial fibrillation at late follow-up. Prevalence of late thromboembolic events was similar in patients with preoperative sinus rhythm compared with that in those with atrial fibrillation. These data suggest that mitral valve repair should be done before or soon after the onset of atrial fibrillation to maximize the chance of postoperative sinus rhythm and avoid long-term anticoagulation with warfarin. However, the early and late results of mitral valve repair in patients with chronic atrial fibrillation are good, and concomitant operation for supraventricular arrhythmia must have negligible morbidity and no adverse effect on operative mortality.

Novel technique to bioassay endocardium-derived nitric oxide from the beating heart.

Nitric oxide is a potent vasodilator and antiplatelet substance released by the vascular endothelium. In the current study, isolated rabbit hearts were perfused retrograde in the aortic root with a balanced salt solution using a Langendorff technique. To perfuse the right cardiac chambers, an inflow cannula was placed in the superior vena cava and an outflow cannula in the right ventricular apex via the pulmonary artery. To detect endocardial vasodilator production, right heart perfusate was used to bathe a "bioassay" segment of canine coronary artery denuded of endothelium. Perfusate from unstimulated hearts did not alter smooth muscle tone in the bioassay tissue. Calcium inophore, a potent stimulus for endothelial nitric oxide production, produced relaxation of the bioassay smooth muscle when added to the cardiac perfusate but not when applied directly to the bioassay segment. Cardiac effluent vasodilator activity was abolished by removal of the endocardium or addition of nitric oxide synthesis inhibitors, but not by prostanoid inhibitors. These experiments describe a practical method to bioassay endocardial nitric oxide production in the beating heart.

Pericardiectomy in calcific constrictive pericarditis aided by Midas Rex drill.

Surgery for constrictive pericarditis has become a rare entity now. Various non-cardiac surgical measures are sometimes tried to remove the calcific plaques on the surface without damaging the underlying cardiac structures. We report a case of severe calcific pericarditis in which the Midas Rex neurosurgical drill was successfully used to facilitate pericardiectomy. Such a case has not been previously reported in the literature.

Coronary artery bypass grafts in situs inversus.

Coronary artery bypass grafting in dextrocardia is rare. A case is described for the first time where both arterial and venous conduits were used. The subtle changes required in the conduct of the operation are highlighted.

Effects of micromolar concentrations of manganese, copper, and zinc on alpha1-adrenoceptor-mediating contraction in rat aorta.

To determine the influences of the Mn, Cu, and Zn on alpha1-adrenoceptor (AR)-mediated vasoconstriction, we investigated their effects on vasoconstriction produced by the alpha1-AR agonist phenylephrine in isolated rings of rat thoracic aorta. The cumulative concentration-contraction curves for phenylephrine were obtained in the absence and presence of Mn (0.3, 1, 3 microM), Cu (1, 10, 16 microM), and Zn (0.3, 1, 10 microM). Mn, Cu, and Zn each inhibited phenylephrine-mediated contraction in a dose-dependent manner. The maximal phenylephrine-induced contraction was significantly reduced by the pretreatment of the arterial rings with 10 and 16 microM Cu (p<0.05). The results suggest that variations in the plasma concentrations of metal might lead to changes in alpha1-AR-mediated constrictive response.

Successful repair of traumatic aortic tears using left heart bypass.

Aortic tears commonly occur in multiply injured patients. Recognizing this injury is important. A chest X-ray is helpful and a CT-angiogram or aortogram confirmatory. After attending to life-threatening injuries, the aortic tear should be repaired immediately. Using the left heart bypass technique has the lowest risk of operative neurologic injury. We review our experience over the last 2 years, discuss our preferred technique and report on the outcome.

Minimally invasive repair of atrial septal defects--a case series.

INTRODUCTION: Repair of atrial septal defects in adults has become so safe that emphasis is now placed on improving cosmesis without compromising safety. The results of our series of minimally invasive repair of atrial septal defects done through a lower partial sternotomy are reported. MATERIALS AND METHODS: Eight adult patients underwent minimally invasive repairs of atrial septal defects over a period of 1 year (Group 1). Conventional repairs of atrial septal defects were performed in 26 patients over the same period (Group 2). We describe the technique and compare our results on time taken for surgery, bypass time, cross clamp time, time to extubation and total hospital stay. Early complications and complications at 1 year are also presented. RESULTS: No difference in the demographic data was found between the two groups. The time taken for surgery was more, while cross clamp times and bypass times were shorter in Group 1. There was also no difference in the amount of blood loss, early postoperative complications and later complications like cardiac rhythm or wound pain. CONCLUSION: The improved cosmetic appearance, both in males and females, is an important factor to recommend minimally invasive repair of atrial septal defects in an adult population. Surgical closure of atrial septal defects can be performed through a lower partial sternotomy without compromising access or safety with good cosmetic outcome.

Surgery for atrial fibrillation.

Atrial fibrillation is the most common sustained cardiac arrhythmia and is associated with significant morbidity and mortality. Surgical treatment is the most effective means of curing atrial fibrillation. The classic Cox maze procedure eliminates atrial fibrillation in more than 90% of patients and has remained the gold standard in surgery for atrial fibrillation. Despite being highly effective, the complexity of the procedure and long operating time associated with the operation has prevented its widespread application by surgeons. Advances in the understanding of the pathogenesis of atrial fibrillation and development of new ablation technologies have fuelled renewed interest in and development of surgical ablation procedures for atrial fibrillation. These new procedures are simpler and easily reproducible and cure atrial fibrillation in approximately 80% of patients. This article reviews the development of surgery for atrial fibrillation and our experience with the radiofrequency Cox maze III procedure.

Changing the institutional practice of prolonged mechanical ventilation after coronary artery bypass graft surgery to early extubation.

Since 1997 some of our cardiac anaesthetists have, whenever possible, extubated the patients early after cardiac surgery to improve their level of comfort, to allow an early return of the cardiopulmonary physiological function, and to help reduce health care costs. After a few months of implementing this practice, an audit was carried out to evaluate the success of early extubation after coronary artery bypass graft (CABG) surgery. Over a 6-month period starting from May 1997, the perioperative data of 110 consecutive patients with good or moderate left ventricular function scheduled for elective CABG were prospectively collected and analysed. The anaesthetic regime was according to the preference of the anaesthetists. Initially consent was obtained from the surgeons when the extubation criteria were fulfilled, but subsequently as the practice became more accepted by the surgeons, extubation was initiated by the anaesthetists. Within 4 hours of admission into the intensive care unit (ICU), 50 (45.5%) of the 110 patients satisfied the early extubation criteria and were extubated. The extubation criteria are described in the article. For the remaining patients, the median duration of mechanical ventilation was 14.3 hours. The profiles of the two groups of patients and the possible reasons for not extubating early are discussed. Forty-five per cent of the patients with moderate to good ventricular function were extubated safely within 4 hours of admission into the ICU after CABG surgery. With gradual acceptance of the practice and a change in mindset amongst all the care givers, more patients can benefit from this practice. This article highlights the challenges associated with changing institutional practices with respect to the postoperative care of cardiac patients.

Percutaneous transcatheter aortic valve replacement: first transapical implant in Asia.

Percutaneous transcatheter implantation of the aortic valve has been demonstrated as an alternative to open heart surgery in high-risk patients with symptomatic severe aortic stenosis (AS) who are not suitable for open surgery. The majority of these new devices are delivered via the transfemoral approach. However, due to the current size of delivery sheaths, the small and tortuous iliofemoral anatomy makes this approach challenging. The transapical approach provides a viable option for this patient subgroup. The first-in-Asia transcatheter aortic valve implantation via the transapical route is described. A 79-year-old Chinese woman with symptomatic severe AS and peripheral arterial disease, who was at high surgical risk, was successfully treated, and had good functional and haemodynamic results at the three-month follow-up.

Resection of a giant malignant mediastinal peripheral nerve sheath tumour under cardiopulmonary bypass.

Malignant peripheral nerve sheath tumour (MPNST) is a rare occurrence in the mediastinum. It is biologically aggressive and is generally resistant to chemoradiation therapy. The mainstay of treatment is complete surgical resection. We report a large MPNST which invaded into the adjacent aortic wall in a 50-year-old man. Extensive resection, which included aortic reconstruction under cardiopulmonary bypass and deep hypothermic arrest, was necessary for a good long-term outcome.

Percutaneous transcatheter aortic valve replacement: first transfemoral implant in Asia.

Surgical aortic valve replacement (AVR) is the standard of care for patients with symptomatic severe aortic stenosis (AS), providing relief of symptoms and prolonging survival. However, many patients are either denied or not offered surgery due to high surgical risk or non-operability for open AVR. The technology of percutaneous aortic valve implantation emerged in 2002, and has since evolved rapidly with satisfactory results. Currently, almost all the procedures are performed predominantly in Europe and North America. The first-in-Asia percutaneous transcatheter aortic valve implantation via the transfemoral route is described. A 77-year-old man with symptomatic severe AS and at high surgical risk was successfully treated, with sustained clinical improvement and satisfactory haemodynamic results at 30-day follow-up.

The NRG1 gene is frequently silenced by methylation in breast cancers and is a strong candidate for the 8p tumour suppressor gene.

Neuregulin-1 (NRG1) is both a candidate oncogene and a candidate tumour suppressor gene. It not only encodes the heregulins and other mitogenic ligands for the ERBB family, but also causes apoptosis in NRG1-expressing cells. We found that most breast cancer cell lines had reduced or undetectable expression of NRG1. This included cell lines that had translocation breaks in the gene. Similarly, expression in cancers was generally comparable to or less than that in various normal breast samples. Many non-expressing cell lines had extensive methylation of the CpG island at the principal transcription start site at exon 2 of NRG1. Expression was reactivated by demethylation. Many tumours also showed methylation, whereas normal mammary epithelial fragments had none. Lower NRG1 expression correlated with higher methylation. Small interfering RNA (siRNA)-mediated depletion of NRG1 increased net proliferation in a normal breast cell line and a breast cancer cell line that expressed NRG1. The short arm of chromosome 8 is frequently lost in epithelial cancers, and NRG1 is the most centromeric gene that is always affected. NRG1 may therefore be the major tumour suppressor gene postulated to be on 8p: it is in the correct location, is antiproliferative and is silenced in many breast cancers.