Tripled yield in direct-drive laser fusion through statistical modelling

Focusing laser light onto a very small target can produce the conditions for laboratory-scale nuclear fusion of hydrogen isotopes. The lack of accurate predictive models, which are essential for the design of high-performance laser-fusion experiments, is a major obstacle to achieving thermonuclear ignition. Here we report a statistical approach that was used to design and quantitatively predict the results of implosions of solid deuterium-tritium targets carried out with the 30-kilojoule OMEGA laser system, leading to tripling of the fusion yield to its highest value so far for direct-drive laser fusion. When scaled to the laser energies of the National Ignition Facility (1.9 megajoules), these targets are predicted to produce a fusion energy output of about 500 kilojoules-several times larger than the fusion yields currently achieved at that facility. This approach could guide the exploration of the vast parameter space of thermonuclear ignition conditions and enhance our understanding of laser-fusion physics.

Magnetic engineering of stable rod-shaped stem cell aggregates: circumventing the pitfall of self-bending

A current challenge for tissue engineering while restoring the function of diseased or damaged tissue is to customize the tissue according to the target area. Scaffold-free approaches usually yield spheroid shapes with the risk of necrosis at the center due to poor nutrient and oxygen diffusion. Here, we used magnetic forces developed at the cellular scale by miniaturized magnets to create rod-shaped aggregates of stem cells that subsequently matured into a tissue-like structure. However, during the maturation process, the tissue-rods spontaneously bent and coiled into sphere-like structures, triggered by the increasing cell-cell adhesion within the initially non-homogeneous tissue. Optimisation of the intra-tissular magnetic forces successfully hindered the transition, in order to produce stable rod-shaped stem cells aggregates.

Use of magnetic forces to promote stem cell aggregation during differentiation, and cartilage tissue modeling

Magnetic forces induce cell condensation necessary for stem cell differentiation into cartilage and elicit the formation of a tissue-like structure: Magnetically driven fusion of aggregates assembled by micromagnets results in the formation of a continuous tissue layer containing abundant cartilage matrix.

Examination of periodontal pathogens in stenotic valve specimens and in whole blood samples in patients affected by aortic valve stenosis and chronic periodontitis

Periodontitis may be a risk factor for atherosclerosis and coronary heart disease. The influence of periodontal pathogens in cardiovascular diseases needs further investigation. Therefore, the aims of this clinical study are: to test the presence of periodontal bacteria DNA in aortic valves and to assess the concomitant presence of the same periodontal bacteria DNA in whole blood samples in patients affected by aortic valve stenosis and chronic periodontitis. Nineteen consecutive patients (12 males and 7 females, age: 49-85 years) were enrolled in this study after having been subjected to a complete periodontal evaluation to confirm the diagnosis of chronic periodontitis. All patients were scheduled for aortic valve replacement surgery. After clinical and microbial periodontal examination, the aortic valve tissue specimens were obtained by excision during valve replacement surgery and the patients were subjected to the whole blood sampling before the surgery. The polymerase chain reaction technology was used to detect the putative periodontal pathogens Tannerella forshytia, Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Prevotella intermedia, Fusobacterium nucleatum, Campylobacter rectus, Eikenella corrodens and Treponema denticola. Neither the 19 aortic valve specimens nor the blood samples were positive for the genoma of the selected periodontal pathogens. The selected periodontal pathogens did not colonize the aortic valve of patients affected by stenosis and bacterial genoma was not present in whole blood samples. A high blood pressure at the aortic valve may prevent the adhesion and proliferation of bacterial colonies.

An endothelin-converting enzyme homologue in the locust, Locusta migratoria: functional activity, molecular cloning and tissue distribution

Endothelin-converting enzyme is the key enzyme in the process of endothelin production. Endothelin is a peptide that plays an important role in vasoconstriction and the development of neural crest-derived cells in vertebrates. Activity assays performed on membrane extracts from Locusta migratoria brain revealed the existence of a protease activity responsible for the formation of mature endothelin-1 from its precursor, big endothelin. Cloning experiments led to a cDNA sequence (Lom ECE) with an open reading frame of 727 amino acid residues displaying all the characteristic ECE features. A comparison of ECE activity levels among different tissues of the locust showed a high enzyme activity in the gonads and midgut. RT-PCR experiments showed a wide tissue distribution of Lom ECE mRNA, with transcription being most abundant in brain tissue.

Simultaneous surgical treatment of chronic post-traumatic aneurysm of the thoracic aorta, diaphragmatic hernia and giant emphysema bulla

Thoraco-abdominal blunt trauma can lead to multiple injuries of several organs. We report a case of a patient in whom, 10 years after a trauma, a chest X-ray showed visceral herniation into the left thorax. Angio computed tomographic scan (CTS) and magnetic resonance imaging (MRI) confirmed these lesions and also showed a saccular thoracic aortic aneurysm. During the surgical procedure a giant post-traumatic emphysema bulla of the left lower pulmonary lobe was discovered and repaired. In the presence of diaphragmatic injuries, CTS and MRI are mandatory for excluding other organ involvement, and during the surgical procedure, careful inspection of left thorax and abdomen should always be done to repair other possible injuries not seen before.

Relation of the -174 G/C polymorphism of interleukin-6 to interleukin-6 plasma levels and to length of hospitalization after surgical coronary revascularization

Interleukin (IL)-6 plasma levels are predictive of major cardiovascular events. The -174 G/C promoter polymorphism of the IL-6 gene affects basal levels in vivo and transcription rates in vitro, but its association with IL-6 acute phase levels among patients with coronary artery disease has not been investigated. In 111 patients with multivessel coronary artery disease undergoing elective coronary artery bypass graft surgery, we prospectively assessed genotype at position -174 and serial blood levels of IL-6 and other inflammatory indexes. Clinical and surgical characteristics did not differ among genotypic groups. IL-6 levels--measured daily up to 72 hours before surgery, after surgery, and at discharge--showed a mean 17-fold increase, peaking at 24 hours (p <0.0001). IL-6 levels (but not fibrinogen, white-blood cell count, and C-reactive protein values) differed significantly according to the -174 genotype (p = 0.042 for difference between areas under the curve), the 62 GG homozygotes exhibiting higher concentrations than the 49 carriers of the C allele (widest difference at 48 hours, p = 0.015 in multivariate analysis). GG homozygosity was associated with longer stays in the intensive care unit (2.5 +/- 3.4 vs 1.4 +/- 0.9 days, p = 0.02) and in the hospital (6.7 +/- 4.0 vs 5.3 +/- 1.4 days, p = 0.02) than C carriership. Rates of postoperative death, myocardial infarction, and stroke were 8% in GG homozygotes and 2% in C-carriers (p = 0.16). The IL-6-174 GG genotype is associated with higher acute phase levels of IL-6 and with longer stays in the hospital and in the intensive care unit than C allele carriership after surgical coronary revascularization.

Clinical and angiographic effects of chronic calcium channel blocker therapy continued beyond first postoperative year in patients with radial artery grafts: results of a prospective randomized investigation

BACKGROUND

This study was conceived to elucidate the clinical and angiographic effects of chronic calcium channel blocker therapy (CCCBT) continued after the first postoperative year in patients in whom the radial artery (RA) was used for myocardial revascularization.

METHODS AND RESULTS

Patients who received RA grafts at our institution and who at 1 year had no scintigraphic evidence of ischemia in the RA territory or angiographic evidence of RA malfunction (n=120) were randomly assigned to continue (n=63) or suspend (n=57) the CCCBT with diltiazem (120 mg/d). After 5 years, all patients were reassessed clinically and by stress myocardial scintigraphy, and 87 of them (45 from the continued group that continued CCCBT and 42 from the group that suspended CCCBT) were restudied angiographically. No differences regarding either the clinical and scintigraphic results or the RA angiographic status were demonstrated between the 2 groups.

CONCLUSIONS

After the first postoperative year, the continuation of CCCBT does not affect RA graft patency or clinical and scintigraphic results.

An unusual source of massive intra-abdominal hemorrhage during cardio-pulmonary bypass

Intra-abdominal hemorrhage occurring while on cardio-pulmonary bypass (CPB) is a rare and potentially lethal event during coronary artery bypass procedures. We herein report an unusual case in which massive intra-abdominal bleeding during CPB originated from a previously undiagnosed ovarian tumor, leading to acute anemization and hemodynamic instability and requiring emergency gynecologic surgery.

Mediastinitis following graft replacement of the ascending aorta: conservative approach by omental transposition

A 57-year-old patient underwent prosthetic replacement of a previously implanted ascending aorta graft and developed a periprosthetic purulent collection 1 month later. He was successfully treated by debridement of infected tissues, antiseptic irrigation and transposition of an omental flap. The postoperative course was uneventful. A chest computed tomography scan performed 15 months later showed no signs of perigraft infection. Prompt conservative surgical treatment including omental transposition can be effective in the treatment of mediastinitis following graft replacement of the ascending aorta.

Highly sensitive and selective fluorescence assays for rapid screening of endothelin-converting enzyme inhibitors

The highly potent vasoconstrictor peptide endothelin (ET) is generated from an inactive precursor, big endothelin (bET), by endothelin-converting enzyme (ECE). ECE is a phosphoramidon-sensitive zinc metallopeptidase, which is closely related to neprilysin (neutral endopeptidase). It is possible that compounds which inhibit the formation of ET may be used as new drugs for the treatment of cardiovascular diseases. Such an approach requires a fast, simple and selective assay to measure ECE activity, allowing rapid screening of inhibitors. We describe here two new ECE substrates based on the concept of 'intramolecularly quenched fluorescence' which may fulfill this aim. One, S(1) [Pya(21)-Nop(22)-bET-1(19--35)], is the (19--35) fragment of the natural peptide big-ET-1(1--38), which is modified by introducing the fluorescent amino acid, pyrenylalanine (Pya), in position 21 and a quencher, p-nitrophenylalanine (Nop), in position 22. The second substrate (S(2)) is a small peptide, Ac-Ser-Gly-Pya-Lys-Ala-Phe-Ala-Nop-Gly-Lys-NH(2), from a biased substrate peptide library. The recombinant, hECE-1c, cleaved both Pya(21)-Nop(22)-bET-1(19--35) and the natural substrate selectively between residues 21 and 22, whereas cleavage occurred between alanine and phenylalanine in the small peptide. In both cases, this generated intense fluorescence emission. The synthesis and kinetic parameters of these substrates are described. These assays, which can be used directly on tissue homogenates, are the most sensitive and selective described to date for ECE, and are easily automated for a high-throughput screening of inhibitors.

Should severe monolateral asymptomatic carotid artery stenosis be treated at the time of coronary artery bypass operation?

OBJECTIVE

The optimal treatment of severe monolateral asymptomatic carotid artery stenosis (SMACS) in patients undergoing coronary artery bypass grafting (CABG) is still controversial.

MATERIALS AND METHODS

This study is based on the in-hospital and mid-term (>5 years) clinical results of a cohort of 139 consecutive CABG patients with SMACS operated at our Institution between January 1989 and December 1995. In the first 73 patients (no carotid surgery group), the SMACS was left untouched at the time of coronary surgery, whereas in the remaining 66 (carotid endoarterectomy group), the carotid stenosis was treated either immediately before or concomitantly with the CABG procedure (depending on the severity of the anginal symptoms).

RESULTS

The overall preoperative characteristics of the patients were comparable. The in-hospital results were similar between the two groups with regard to mortality, stroke and major postoperative complications. However, at mid-term follow-up, significantly more patients of the no carotid surgery group suffered cerebral events (transient or permanent) ipsilateral to the SMACS or the lesion had to be operated on.

CONCLUSIONS

The concomitant treatment (either staged or simultaneous) of SMACS at the time of CABG does not influence the in-hospital results, but confers significant neurological protection during the years after the operation.

Combined Surgery for cardiac and carotid disease: management and results of a rational approach

OBJECTIVES

The aim of the present study was to apply a rational plan for simultaneous cardiac and carotid surgery in high-risk patients.

MATERIALS AND METHODS

A consecutive series of 89 patients with coexisting severe cardiac and carotid disease were operated on during a 5-year period with routinary carotid shunting, moderate hypothermia and balanced anaesthesia. The combined surgical procedures were coronary artery by-pass grafts (CABG) + carotid endarterectomy (CEA) in 81 patients, CABG + CEA + aortic valve replacement (AVR) in four patients, and four cases of CEA + AVR. RESSULTS: Two deaths (2%), three acute myocardial infarctions (3%) and one (1%) major stroke occurred in five patients during the perioperative (30 days) period for a combined rate of death and/or disabling stroke of 3%. There were five reversible neurological deficits. Carotid and aortic mean clamping times were 9 and 60 min respectively. Patients were discharged after a mean length of stay in Intensive Care Unit (ICU) of 131 h and 7 days of hospitalisation post-ICU.

CONCLUSIONS

Based on our results, combined interventions of CEA and CABG can be performed with an acceptable morbidity and mortality when severe carotid stenosis is associated with advanced, symptomatic cardiac disease. The management of these patients needs careful and appropriate pre-intra and post-operative assessment and timing aimed to reduce the ischaemic injuries, both cardiac and cerebral, especially during CBP time.

Coronary angiodysplasia of epicardial and intramural vessels

A case of coronary angiodysplasia combining large aneurysms of epicardial arteries with diffuse malformation of intramural vessels is reported. Clinical presentation may mimic a vascularized cardiac tumor. Although leaking of the aneurysms in the pericardial space may occur, this entity seems to have a benign prognosis not requiring surgical repair.

The unclampable ascending aorta in coronary artery bypass patients: A surgical challenge of increasing frequency

BACKGROUND

The unclampable ascending aorta (UAA) is a condition increasingly encountered during CABG procedures. We report our experience with CABG patients with UAA and place particular emphasis on the preoperative diagnosis and surgical management.

METHODS AND RESULTS

UAA was diagnosed in 211 of 4812 consecutive CABG patients (4.3%). On the basis of the chest radiograph, echocardiogram, and coronary angiograph, a preoperative diagnosis was achieved in only 58 patients (27.4%). An age of >70 years, diabetes, smoking, unstable angina, diffuse coronaropathy, and peripheral vasculopathy were all predictors of UAA. Patients were treated with hypothermic ventricular fibrillation (no-touch technique n=129) or beating heart revascularization (no-pump technique n=82) depending on the possibility of founding an arterial cannulation site. The overall in-hospital mortality rate was 2.8% (6 of 211) with no differences between the 2 surgical strategies. The no-touch technique was associated with a greater incidence of neurological complications (stroke and transient ischemic attack), renal insufficiency, and stay in the intensive care unit and hospital. However, at midterm follow-up, more patients of the no-pump group had ischemia recurrence.

CONCLUSIONS

A preoperative diagnosis of UAA is achievable only in a minority of patients, which highlights the necessity revising the current diagnostic protocols. The use of the no-touch technique is associated with an high perioperative risk but a superior possibility of complete revascularization, whereas adoption of the no-pump strategy ensures a smoother postoperative course at the expense of an higher incidence of ischemia recurrence.

Elevated levels of C-reactive protein before coronary artery bypass grafting predict recurrence of ischemic events

C-reactive protein was measured in 86 patients undergoing coronary artery bypass graft surgery. Patients were followed up for 3.2 years (range 1 to 6). Patients with C-reactive protein > or = 3 mg/L had significantly increased risk of recurrent ischemia at 1 to 6 years after intervention.

Individualized surgical strategy for the reduction of stroke risk in patients undergoing coronary artery bypass grafting

BACKGROUND

This study was designed to evaluate the efficacy of a protocol of systematic screening of the ascending aorta and internal carotid arteries and individualization of the surgical strategy to the ascending aorta and internal carotid arteries status in reducing the stroke incidence among patients undergoing coronary artery bypass grafting.

METHODS

On the basis of a pre- and intraoperative screening of the ascending aorta and internal carotid arteries, 2,326 consecutive patients undergoing coronary artery bypass grafting were divided in low, moderate, and high neurologic risk groups. In the high-risk group dedicated surgical techniques were always adopted and the reduction of the neurologic risk was considered more important than the achievement of total revascularization.

RESULTS

The incidence of perioperative stroke in the high-risk group was similar to those of the other two groups (1.1 versus 1.3 and 1.1%, respectively; p = not significant); however, angina recurrence was significantly more frequent in the high-risk group.

CONCLUSIONS

The described strategy allows a low rate of perioperative stroke in high-risk patients undergoing coronary artery bypass grafting. Whether the reduction of the neurologic risk outweighs the benefits of complete revascularization remains to be determined.

Perioperative management of a patient with Werlhof disease undergoing myocardial revascularization

We herein report the case of a patient with idiopathic thrombocytopenic purpura (Werlhof disease) and coronary artery disease undergoing myocardial revascularization. The use of monomeric immunoglobulins, corticosteroids, platelets transfusion, use of a cell saver, normothermic cardiopulmonary bypass, aprotinine and homologous blood transfusion were combined in order to minimize the risk of bleeding complications in the postoperative period.

Midterm clinical and angiographic results of radial artery grafts used for myocardial revascularization

OBJECTIVE

To evaluate the midterm angiographic results of the use of radial artery grafts for myocardial revascularization.

METHODS

The first 68 consecutive surviving patients who received a radial artery graft proximally anastomosed to the aorta at our institution were studied again at 5 years (mean 59 +/- 6.5 months) of follow-up; 48 of these patients had previously undergone an early angiographic examination. The response of the radial artery to the endovascular infusion of serotonin was evaluated 1 and 5 years after the operation, and the midterm status of the radial artery graft was correlated with the degree of preoperative stenosis of the target vessel and with calcium-channel blocker therapy.

RESULTS

The patency and perfect patency rates of the radial artery grafts 5 years after the operation were 91.9% and 87.0%, respectively. All radial artery grafts that were patent early after the operation remained patent at midterm follow-up, and early parietal irregularities in 7 patients were seen to have disappeared after 5 years. The early propensity toward graft spasm after serotonin challenge was markedly decreased at midterm follow-up. The continued use of calcium-channel antagonists after the first postoperative year did not influence the radial artery graft status, whereas the preoperative severity of the target-vessel stenosis markedly influenced the angiographic results.

CONCLUSIONS

The midterm angiographic results of radial artery grafts used for myocardial revascularization are excellent. The correct surgical indication is essential. Continued therapy with calcium-channel antagonists after the first year does not influence the midterm angiographic results.

Tepid systemic perfusion and intermittent isothermic blood cardioplegia in coronary surgery

BACKGROUND

To evaluate the safety and effectiveness of tepid perfusion and isothermic blood cardioplegia in coronary surgery.

METHODS

We studied 200 patients undergoing myocardial revascularization: 100 procedures were performed with moderate systemic hypothermia (28 degrees C) and cold crystalloid cardioplegia (4 degrees C); the other 100 patients received tepid systemic perfusion (TP) (34 degrees C) and intermittent blood cardioplegia at the same temperature according to the minicardioplegia technique (Group 2). The two groups were comparable with regards to age, extent of disease, preoperative left ventricular function and extra-corporeal circulation (ECC) time.

RESULTS

In the tepid group we observed a higher incidence of spontaneous resumption of cardiac rhythm at cross-clamp removal compared to the hypothermic group (93% vs 34%; p<0.001). No difference was found in cardiac index at specified intervals, myocardial enzymes, inotrope requirements, arrhythmias, need for vasopressors and postoperative blood loss. Fluid balance at the end of ECC was significantly lower in the tepid group (343+/-635 ml vs 883+/-925 ml; p<0.001). Hospital mortality and morbidity were the same in the two groups.

CONCLUSIONS

Our data suggest that TP and isothermic blood cardioplegia represent a simple, safe and effective method of systemic and myocardial protection which may be an alternative to traditional hypothermia.

Systematic clinical and angiographic follow-up of patients undergoing minimally invasive coronary artery bypass

OBJECTIVE

We herein analyze the results of the systematic clinical and angiographic control performed in a series of 77 consecutive patients undergoing minimally invasive coronary artery bypass.

METHODS AND RESULTS

From January 1995 to June 1997, 77 patients underwent minimally invasive coronary artery bypass at our institution. There was one inhospital death, one noncardiac late death, and five patients had to be reoperated for graft malfunction. A total of 76 patients underwent postoperative angiographic follow-up. In 66 cases (86.8%) the thoracic artery graft, the target vessel, and the anastomosis were patent and functioning normally. In one case the graft was occluded. In the remaining nine cases the thoracic artery graft was patent but with major anomalies of either the anastomosis, the target vessel, or the course of the thoracic artery. Patients operated using especially designed instruments had angiographic results clearly superior to those of patients operated using conventional instrumentation (perfect patency rate 100% vs 81.8%). At a mean follow-up of 18 months, 98.5% of the surviving patients are asymptomatic with negative myocardial scintigraphy.

CONCLUSIONS

The perfect patency rate of minimally invasive revascularization performed without the use of dedicated instruments is unacceptably low. The use of specific devices is likely to result in a substantial improvement in the angiographic results.

Characterization of Glu350 as a critical residue involved in the N-terminal amine binding site of aminopeptidase N (EC 3.4.11.2): insights into its mechanism of action

The molecular components ensuring the strict exopeptidase action of aminopeptidase N (APN) and related zinc aminopeptidases of the M1 family have not yet been clearly established. The specific recognition of the N-terminal amino acid of the substrates by the enzymes has been proposed to involve either the complexation of the free amino group by the catalytic zinc ion or an interaction with an anionic binding site, which could be constituted by an aspartate or glutamate residue. To investigate the existence of such an ionic binding site, site-directed mutagenesis experiments have been performed on acidic residues of pig APN. Given that aminopeptidases of the M1 family are likely to have a common mechanism of action, only strictly conserved residues were mutated. As compared to the wild-type enzyme, the mutation D220E led only to slight modifications in the kinetic parameters of the enzyme and in the Ki values of various inhibitors, indicating that this residue is not critically involved in the hydrolytic mechanism. In contrast, the mutations E350Q and E350D induced a large decrease in enzyme activity, essentially due to modifications in kcat, whereas the E350A mutation led to an almost completely inactive enzyme. Moreover, among the inhibitors tested, only those acting as transition state analogs showed significant increases in their Ki values. These data are in favor of E350 belonging to the "anionic binding site" in APN. A mechanism of action, derived from that of thermolysin, is proposed for these aminopeptidases, which explains the importance of E350 in transition state formation, rather than in the Michaelis complex.

Lesions of the target vessel during minimally invasive myocardial revascularization

BACKGROUND

Minimally invasive coronary artery bypass grafting has recently been introduced into cardiac surgery. In this report we discuss the incidence of surgically induced distal target vessel stenosis in patients who undergo the minimally invasive coronary artery bypass grafting procedure, which represents a major drawback of the procedure in our experience.

METHODS

Doppler evaluation of mammary artery flow was performed postoperatively in all 55 patients who underwent minimally invasive coronary artery bypass grafting at our institution. Angiography was performed in the first 35 consecutive patients for control purposes and in 2 patients who complained of angina recurrence.

RESULTS

In 32 of the first 35 consecutive patients, the anastomosis was found to be functioning normally and the distal left anterior descending artery was normal; in the remaining 3 patients we found mammary artery occlusion, anastomotic stenosis, and stenosis of the anastomosis and the distal left anterior descending artery in 1 patient each. A distal left anterior descending artery stenosis was found in the only 2 patients who underwent late angiography.

CONCLUSIONS

Surgically induced distal target vessel stenosis represents a major drawback of minimally invasive coronary artery bypass grafting in our experience. Further improvement in the means of achieving coronary artery occlusion, as well as in anticoagulant and antiplatelet therapy, is mandatory before minimally invasive coronary artery bypass grafting can be confidently accepted into clinical practice.

Early results with the minimally invasive thoracotomy for myocardial revascularization

OBJECTIVE

We report the early results of the left anterior descending artery revascularization through a minimally invasive thoracotomy, examining the main technical aspects of the operation.

METHODS

From January 1995 to September 1996, 51 patients underwent myocardial revascularization through a mini-thoracotomy on beating heart without cardiopulmonary bypass. The main indication to operation was limited lesions of the left anterior descending artery with contra-indications or high risk of failure of angioplasty. The position of the patient was the same than traditional surgery; the chest was opened on the fourth left intercostal space; the left internal mammary artery harvested under direct vision; temporary occlusion of the left anterior descending was obtained prevalently using 5-0 poliypropilene sutures; the anastomosis was performed with single or double 7-0 or 8-0 suture. In six patients the chest was closed and a conventional open-heart operation was performed due to internal mammary artery or left anterior descending unsuitability for minimally invasive revascularization. All the patients were submitted after operation to early angiographic control and/or a Doppler study of the mammary flow.

RESULTS

There was no intra-operative mortality. One patient had a postoperative myocardial infarction of the anterior-lateral wall of the left ventricle, and died after an emergency open-heart operation. In one case the patient was reopened after a few hours for a bleeding. Three patients showed various degrees of anastomotic stenosis at the angiographic control.

CONCLUSIONS

Several technical difficulties can play an important role in the operative outcome because a single repeated technical error could not fully explain these heterogeneous observed failures. The technique of myocardial revascularization through a left anterior small thoracotomy might present several critical points, particularly: (1) the harvesting of LIMA, meaning the preservation of integrity of the arterial wall and adequacy of the length; (2) the method of the temporary closure of the LAD during of the anastomosis; (3) the stabilization of the LAD and the surgical technique of the anastomosis; (4) the methods for intraoperative control of the patency of the anastomosis. All points mentioned have been thought in our experience to be causes of early failure.

The internal mammary artery malperfusion syndrome: late angiographic verification

BACKGROUND

Here we report our experience with the incidence and the surgical treatment of the internal mammary artery (IMA) malperfusion syndrome, evaluate the predictive role of previously described risk factors for the syndrome, and assess the late patency of IMA grafts in patients in whom an IMA malperfusion syndrome was diagnosed and treated by additional saphenous vein grafting of the left anterior descending coronary artery.

METHODS

From June 1992 to November 1995, 969 IMAs were anastomosed to the left anterior descending coronary artery system. In 11 patients, IMA malperfusion syndrome was diagnosed and treated by additional saphenous vein grafting of the LAD. There were 8 men and 3 women with a mean age of 58.9 years. The angiographic and clinical data for each patient were reviewed, and all but 1 surviving patient underwent late angiographic control (mean follow-up, 18 months; range, 4 to 46 months).

RESULTS

One patient died in the hospital. No previously described risk factor was strongly associated with the occurrence of IMA malperfusion syndrome. Late angiography revealed a malfunctioning IMA graft in 7 of the 9 patients. A string sign was observed in 1 patient and a normally functioning IMA anastomosed to a diagonal branch not connected to the LAD, in another. In no patient was a widely patent and normally functioning IMA graft observed.

CONCLUSIONS

In our series, a high proportion of IMA grafts were found to be malfunctioning at late angiography. This observation, in contrast to previous reports, suggests that IMA malperfusion syndrome can often be attributable to technical problems in harvesting the IMA or in performing the IMA anastomosis. Functional IMA insufficiency seems to play only a marginal role in determining the IMA malperfusion syndrome.

Surgical treatment of recurrence of an aneurysm of aberrant right subclavian artery

A 52-year-old woman underwent incomplete resection of an aneurysm of the aberrant right subclavian artery. Three years later she was hospitalized because of a right superior mediastinal mass on the chest X-ray and a new angiography revealed dilatation of the remaining part of the aberrant right subclavian artery near its origin and involving the adjacent thoracic aorta and the distal aortic arch. At surgery, a left posterolateral thoracotomy in the fourth intercostal space was performed. Using deep hypothermia and circulatory arrest the aneurysm was excised and the aortic tract adjacent to the aneurysm was replaced with a Dacron prosthesis.

Surgical treatment of massive pulmonary embolism

Surgical treatment of massive pulmonary embolism (PE) is usually performed in cases of contraindications to fibrinolysis (trauma and/or recent surgery). Additional indications for the embolectomy are either clinical (shock low cardiac output, cardiac arrest) or angiographic (occlusion of more than 80% of pulmonary arterial bed). Due to the emergency setting, PE is often diagnosed only on a clinical basis (10-30% of the cases). Embolectomy is usually performed using cardio-pulmonary bypass (CPB). Trendelenburg procedure can be indicated in desperate situations. No general agreement exists concerning the role of interruption of the inferior vena cava (IVC), in order to prevent PE recurrence. Usually, interruption of the IVC is performed in cases of contraindications to anticoagulant therapy or in presence of recurrence despite anticoagulation. Operative mortality ranges from 40 to 70%; there are no differences between the two surgical techniques and the major risk factor for death is the preoperative clinical status (shock, and/or cardiac arrest). Anticoagulant therapy affords a low incidence of recurrence.

[Reintervention of myocardial revascularization by left thoracotomy in deep hypothermia. A clinical case]

Herewith we report a case of redo coronary-surgery which was approached through a left thoracotomy and in hypothermic arrest so as to avoid either a demanding dissection with its potential consequences over the functioning grafts and aortic cross-clamping thus making unnecessary any cardioplegia delivery. We describe the surgical procedure and analyze its advantages with respect to the usual median sternotomy approach.

Stimulation of translation by reactive oxygen species in a cell-free system

Wheat germ lysate was used as a model system for in vitro translation. We show that an increase of the exchange surface between the reaction mixture and the atmosphere enhanced the amount of incorporated cysteine, indicating that early arrest of protein synthesis previously observed in such a system was due to oxygen starvation in the reaction mixture. This hypothesis was confirmed since the amount of proteins synthesized and the rate of translation increased when oxygen was added. We show that an addition of hydrogen peroxide to the translation mixture had the same effect as oxygen, allowing us to postulate that stimulation could be due to a common property between both molecules: the oxidizing behaviour. Free radicals in in vitro translation were believed to be involved since the utilization of iron chelating agents inhibited translation. This hypothesis was emphasized by the positive effect of a free radical generating system and the negative effect of free radical scavengers. These experiments suggest that the superoxide radical plays an important role in in vitro translation.

Composite arterial conduits for a wider arterial myocardial revascularization

From October 1991 to May 1993, 130 patients were submitted to myocardial revascularization using complex preformed arterial conduits. The age ranged from 29 to 75 years (mean age, 60.1 years); 121 patients were male. One hundred twenty-six patients had double- or triple-vessel disease. The mean ejection fraction was 0.53 (range, 0.22 to 0.79); only 6 patients had an ejection fraction less than 0.35. In 6 cases the procedure was a reoperation. We used 360 arterial conduits, 163 of which as free grafts (3 left internal mammary arteries, 16 right internal mammary arteries, 86 inferior epigastric arteries, 57 radial arteries, and 1 right gastroepiploic artery). One hundred fifty-four free grafts were anastomosed to one or both internal mammary arteries and one to a radial artery. We constructed 136 complex arterial conduits (branched, lengthened, or both). In 6 cases a double arterial system had to be used in a single patient. There was no operative mortality, and no inotropic or mechanical supports were used. The overall mortality rate was 1.5%. Early angiographic controls (between the 7th and 15th postoperative days) demonstrated 100% patency; late angiographic controls (at a mean interval of 9.5 months after operation) documented a mean patency rate ranging from 94.1% of the radial arteries to 100% of the left internal mammary arteries and right gastroepiploic arteries. At a mean follow-up of 7.2 months (range, 1 to 15 months) all patients are alive without recurrence of symptoms.

[Myocardial revascularization with the internal mammary artery. The indications, technics and results]

This report reviews 218 patients who underwent internal mammary artery (IMA) grafting alone or with vein graft between 1986-1989. Our experience with IMA started with a single attached graft for proximal left anterior descending lesions in young patients affected from stable angina. After that our indications became more extensive. One IMA was utilized in 209 cases, both two IMAs in the remaining 9. Sequential IMA graft was performed in 16 patients and free IMA graft in 8. There were 242 IMA anastomosis and 295 associated vein by-passes. The overall operative mortality was 2.3%. Perioperative complications include myocardial infarction in 3 (1.4%), reoperation for bleeding in 4 (1.8%) and sternal wound complication in 4 (1.8%). These results are comparable to those of patients having only saphenous vein by-pass during the same period. At the follow-up actuarial survival rate at 42 months was 94 1.8% and 90% of these patients were completely asymptomatic. We include that IMA grafting shows low operative risk and provide excellent short term results. Our findings and the high long term patency rate of this conduit encourage us to extend the indication to IMA and to perform those surgical techniques that make possible multiple mammary coronary anastomosis.

[Aortic valve replacement in a case of Takayasu's disease with polydistributed localization]

We report a case of a 49 year-old woman suffering from severe aortic regurgitation due to Takayasu's disease involving the ascending and abdominal aorta and the brachial arteries. The patient was managed successfully with aortic valve replacement. Considering the Literature data, the pathogenesis of the aortic insufficiency and the main surgical and anaesthesiologic problems related to the Takayasu's disease are discussed.

[Aneurysms of the abdominal aorta]

The authors report 73 cases of abdominal aortic aneurysms with particular emphasis to early and long-term results as well as postoperative complications: 4 patients died at admission, 16 were treated with medical therapy, and 53 underwent surgery. Surgical patients were stratified in two groups: 18 emergency cases (group 1) and 35 elective cases (group 2). Early results showed the highest mortality in group 1 cases presenting with shock. Late results, at the end of the follow up, (6 months-8 years), showed a 56.6% 5-year survival rate, with overlapping survival rates after the immediate postoperative period. The most frequent postoperative complications were thrombosis of prosthesis and lymphorrhea. Survival rates of emergency cases were influenced by early diagnosis and prompt aorta clamping. Before surgery an haemodynamic evaluation of all vascular districts seems necessary in elective cases to prevent complications of atherosclerotic disease.

[What is the best treatment in massive pulmonary embolism: anticoagulants, thrombolytics or surgical embolectomy?]

The aim of this work was to identify the best treatment available for massive pulmonary thromboembolism which still remains a frequent and sometimes lethal complication for surgical and non-surgical patients. The Authors underline the difficulties of diagnosis and the need for therapy at the earliest possible stage. At present, clinical management involves the use of: anticoagulants, thrombolytic agents and surgical embolectomy. In conclusion, the authors state that pulmonary thromboembolism, even when massive, has been transformed into a medically interesting pathology which can be cured using heparin and thrombolytic agents. However, surgical treatment is mandatory when patients reveal adverse effects to drug therapy, when medical therapy is insuccessful, or when patients are seriously ill with recurrent cardiac arrest.

[Infectious endocarditis. Role of surgical therapy]

The problem of infectious endocarditis (IE) is approached through a review of personal experience. The series examined consists of patients, 17 with active and 21 dormant infection. Furthermore 12 in the first group, 18 in the second had natural heart valves, while 5 in group I, 3 in group II had been given artificial ones. After an analysis of the aetiopathogenic, clinical and diagnostic aspects of the condition with emphasis on the fact that Staphylococcus aureus is currently more responsible for infections in natural valves and the epidermidis for acute prosthesis infections which have a higher early and late mortality rate (40% in hospital, 33.3% long-term), the paper discusses the criteria for surgical intervention. In line with opinions expressed in the literature, it is pointed out that, while the patient's haemodynamic status is certainly the main criterion for any decision, other factors such as embolism, impaired conduction, kidney failure and expansion of the infection to contiguous tissues, should not be under-estimated.

[Reversibility of left ventricular functional damage after valve replacement in patients with chronic aortic valve insufficiency]

The authors study retrospectively some preoperative echocardiographic findings and their importance as predictors of reversible myocardial dysfunction. The functional status of 57 survivors after isolated aortic valve replacement was evaluated with exercise testing and on this ground the patients, were divided into three groups: A (28 pts) greater than 60%; C (10 pts) less than 40%; B (19 pts) from 40% to 60%. The authors conclude that the postoperative improvement in functional status is strictly correlated with some preoperative echocardiographic indexes (end-diastolic dimension, end-systolic dimension, shortening fraction, mean end-systolic radius/thickness ratio, end-systolic wall stress, myocardial mass, ejection fraction) with are also predictive of operative mortality. The authors consider the principal values of beginning left ventricular impairment: a) end-systolic dimension greater than or equal to 5.5 cm; b) shortening fraction less than 27%; c) mean end-systolic radius/thickness ratio greater than 2.5; d) end-systolic wall stress greater than 240 mmHg.

Valve replacement with the tilting disc Sorin prosthesis in patients with narrow aortic annulus

The Authors summarize their 5-year experience of the clinical use of the Sorin tilting disc prosthesis in 40 patients (group A) with narrow aortic annulus, compared with a control group (group B: 116 patients) where a larger Sorin prosthesis was implanted. Follow-up lasted from 1 to 60 months, with a mean of 25.6 +/- 12.3 in group A and 20.4 +/- 11.9 in group B. Early and late mortality were low: 1/40 and 2/39 (2.5 and 5.1%) in group A and 4/116 and 9/112 (3.4 and 8.0%) in group B (p = NS): only two deaths, one in each group, were prosthesis-related. Actuarial survival was comparable: 91.2% (CL: 96.3-86.1%) in group A and 78.0% (CL: 87.6-68.4%) in group B, as were probability of being event-free and alive, non-reoperated and with few or no symptoms [group A: 61.7% (CL: 72.4-51.0%) and 77.4% (CL: 85.9-68.9%) respectively; group B: 78.8% (CL: 83.4-74.2%) and 61.1% (CL: 85.9-68.9%) respectively]. The Authors conclude that the Sorin tilting disc prosthesis is a reliable valve substitute in the narrow aortic annulus; they recommend that enlargement procedures should be confined only to patients with annulus size less than 19 mm.

[Operative risk in coronary bypass. A multivariate analysis of prognostic factors]

In order to determine the predictors of operative risk in coronary bypass surgery, we have studied 2112 consecutive patients who underwent isolated coronary bypass surgery between January 1979 and September 1984. The overall operative mortality (OM) was 4.4 percent (3.5 percent during the last 3 years). OM increases significantly with age (from O before the age of 30 to 12.3 percent after 70), the functional class (FC) of angina, the FC of dyspnea (NYHA), the creatinine blood level (23.5 percent if greater than 200 mumol/l), the left ventricular end-diastolic pressure and in case of reoperation (16.7 percent), as well as in women (11.6 percent). There is a trend toward higher OM in case of past history of ventricular tachycardia or arterial hypertension, atherosclerotic disease of the lower extremities, left ventricular dysfunction or severe stenosis of the left main coronary artery. OM is not increased in patients with multivessel disease, diabetes or with a past history of myocardial infarction, and is even decreased in obese patients. The variables selected by multivariate analysis were: creatinine blood level, then angina FC, sex, dyspnea FC, age, the absence os obesity, left ventricular dysfunction, the year of surgery and finally reoperation. These results, mainly based on simple clinical variables, should facilitate the therapeutic decisions in borderline indications of coronary bypass surgery.