Biomedical subjects
Publications and source records attributed to G B Luciani.
Primary pulmonary trunk sarcoma is a rare and highly lethal disease. A case of multicentric pulmonary trunk leiomyosarcoma with right and left main pulmonary artery involvement, mimicking massive pulmonary embolism, is described. The importance of a timely diagnosis and of radical surgical excision is discussed.
The surgical management of tetralogy of Fallot has undergone important changes in recent years. Earlier repair of tetralogy of Fallot is now favored by many institutions. At Stanford University Medical Center, we have performed definitive repair of tetralogy of Fallot at the time of presentation, regardless of the child's age, with few exceptions. In this report, we describe our results with early repair, and we believe these support the contention that infants who undergo early repair (< 1 year of age) have postoperative results similar to those of children who undergo repair at an older age. Complications related to shunts are prevented by the infant repairs, and, in the future, reduced ventricular ectopy may be demonstrated to be a benefit of such repairs.
We describe a patient with neonatal Marfan syndrome presenting with massive ascending and descending thoracic aortic aneurysm. Because of rapidly progressive respiratory distress due to tracheobronchial compression, emergency replacement of the descending thoracic aorta with a 12-mm PTFE vascular prosthesis was undertaken at 1 month of age. The postoperative course was complicated by bilateral tension pneumothorax contributing to irreversible respiratory failure. The unique clinico-pathological features and the relevant surgical implications of the case are discussed.
Chronic shortage of donor organs for heart transplantation led us to extend donor age limits. To verify the effectiveness of such a policy we have compared the results of heart transplantation in 45 patients with donors more than 40 years of age (group 1) with those of 72 patients older than 50 years of age who had heart transplantation with younger donors (group 2) between November 1985 and December 1992. The two groups were comparable in terms of mean recipient age, recipient and donor sex, and indication for heart transplantation. Mean donor age was 46 +/- 4 years (range 41 to 59 years) in group 1 and 23 +/- 7 years (range 8 to 39 years) in group 2 (p < 0.001). In group 1 cerebrovascular accidents were more common as the cause of donor death (60% versus 16%, p = 0.001), and no difference was found in ischemic time (144 +/- 47 minutes versus 140 +/- 48 minutes, p = not significant). There were 6 early (< 30 days) deaths in group 1 (13%) and 10 in group 2 (14%; p = not significant). Fatal acute graft failure was more prevalent, but not significantly so, in group 1 (10% versus 5.5%, p = not significant). Mean follow-up was 29 +/- 20 months (range 3 to 78 months) in group 1 and 30 +/- 20 months (range 3 to 80 months) in group 2 (p = not significant). At 5 years actuarial survival was 80% +/- 6% in both groups with comparable graft performance at echocardiographic and hemodynamic control studies. A significant difference was found in freedom from any type of coronary artery abnormality between group 1 (49% +/- 13%) and group 2 (77% +/- 8%) at 5 years (p < 0.05); however, freedom from coronary stenotic lesions only was similar. Major conduction disturbances have occurred more frequently in patients of group 1 (37% versus 12%; p = 0.003) without any difference in the need for permanent pacing. Donors older than 40 years of age can be accepted for heart transplantation with early and long-term results comparable with those obtained with younger donors. The impact of a higher incidence of coronary abnormalities on late performance of older grafts must be assessed at longer follow-up. Our results indicate that, because of the current organ shortage, extension of donor age limits is justified, even up to the sixth decade of life in selected cases.
A rare case of single, pedunculated, ball-like rhabdomyoma of the pulmonary valve, causing moderate right ventricular outflow obstruction in an infant with tuberous sclerosis, is presented. The diagnostic and surgical implications are discussed.
Between January 1987 and September 1991, 112 operative survivors of heart transplantation were initially immunosuppressed with cyclosporin A and azathioprine without prednisone. Eighty-eight patients (79%) remained on a regimen of double therapy for a mean follow-up of 25 +/- 15 months (range, 1 to 54 months), whereas 24 patients (21%) had oral prednisone, 5 mg/day, added to maintenance therapy for persistent or repeated rejection. There were 5 early deaths (4%) because of acute rejection (4 patients) or infection (1 patient). Only 1 patient died late after heart transplantation of chronic rejection. Actuarial survival was 95% +/- 2% and 94% +/- 3% at 12 and 48 months, respectively. Mean rate of acute rejection was 1.7 +/- 1.0 episodes per patient, with a 5% +/- 2% freedom from rejection at 48 months. Ten patients (9%) required in-hospital treatment for infection; the actuarial freedom from infectious episodes was 85% +/- 4% at 48 months. Actuarial freedom from hypertension was 43% +/- 7% at 48 months. At annual catheterization, mean left ventricular ejection fraction was 0.64 +/- 0.08 and 0.62 +/- 0.05 at 1 year and 4 years, respectively, with evidence of coronary lesions in 9 patients (8%). In conclusion, steroid-free immunosuppression after heart transplantation is associated with a high incidence of acute rejection. However, the excellent medium-term survival and the low incidence of both infection and chronic rejection seem to justify a wider use of such treatment.
Severe left ventricular failure in ischemic heart disease may contraindicate conservative surgical procedures. To redefine therapeutic indications, the clinical and angiographic data of 143 patients (137 men and 6 women) with ischemic heart disease and a left ventricular ejection fraction less than 0.30 who were seen by us between June 1985 and December 1990 were retrospectively analyzed. Patients were divided into three groups according to therapy: medical only, 72 (group 1); myocardial revascularization, 20 (group 2); and heart transplantation, 51 (group 3). Clinical status was poorer in group 3, with congestive heart failure as predominant symptom; angina was more frequent in group 2. No difference was noted in hemodynamic variables. Four early deaths (20.0%) occurred in group 2 and 7 (13.7%) in group 3. Follow-up ranged from 1 to 64 months (mean, 22 +/- 19 months), with an actuarial survival of 28% +/- 9%, 80% +/- 8% and 82% +/- 5% at 5 years in groups 1, 2, and 3, respectively. Even though postoperative New York Heart Association class was better in group 3 (1.0 versus 2.3 in group 2; p < 0.01), the difference in survival was not significant. Although in patients with ischemic heart disease and low left ventricular ejection fraction heart transplantation offers the best clinical results, considering the donor shortage, we conclude that myocardial revascularization may still be performed with good midterm results.
Acute myocardial ischemia and infarction due to retrograde coronary artery dissection are uncommon complications after ascending aortic dissection. A case of acute aortic dissection with massive right ventricular failure successfully treated by replacement of the ascending aorta and postoperative right ventricular mechanical support is presented. Although mechanical assistance may be hazardous after ascending aortic replacement, because of the need of anticoagulation, it represents a valid therapeutic option when severe right ventricular failure due to acute myocardial infarction ensues.
Acute cardiac rupture is often a lethal complication of transmural myocardial infarction. A case of successfully treated left ventricular free wall rupture is described. Preoperative hemodynamic stabilization was achieved by intraaortic balloon counterpulsation. A BioMedicus left ventricular assist device was used intraoperatively and postoperatively to obtain long-term intraventricular decompression to allow for suture repair of friable myocardium.
The effects of global ischemia on the contractile system and on sarcoplasmic reticulum (SR) function were studied by measuring the isometric tension and the SR Ca2+ release activity of chemically skinned cardiac fiber preparations from seven patients undergoing open-heart surgery. Ten minutes of ischemia caused 1) a decrease in the myofilament sensitivity to Ca2+ (expected Ca2+ concentration giving half-maximal tension; from 0.69 +/- 0.04 to 1.38 +/- 0.06 microM, n = 7) and in the cooperativity index (Hill coefficient; from 2.61 +/- 0.45 to 0.92 +/- 0.15, n = 7), 2) a decrease in myosin light chain phosphorylation, and 3) a 300% increase in the threshold caffeine concentration for SR Ca2+ efflux channel activation, with a 30% reduction in the rate of Ca2+ release by caffeine at threshold concentrations and a 23% reduction in the rate of release by 20 mM caffeine. After preincubation with 5 microM trifluoperazine, a calmodulin antagonist, the caffeine threshold of ischemic and control cardiac muscle became comparable. Most changes were reversed by reperfusion, while the caffeine threshold was still two times greater than control. These results indicate that ischemia caused alterations of the cardiac muscle contractile apparatus and the SR that were reversed only after reperfusion.
The Starr-Edwards (S-E) mitral valve, Model 6120, has been widely used in the last three decades. Fatty infiltration and subsequent damage of the silastic ball, a phenomenon termed ball variance, has been described only in the first generation aortic ball-valve prostheses, used until 1965. A case of partial ball fracture in a 6120-Model S-E mitral valve prosthesis, occurring 27 years after implantation and presenting with thromboembolism and progressive valve dysfunction, is described.
Explore the source record for details and available documents.
Acute allograft rejection is still a leading cause of both early and late mortality and morbidity after cardiac transplantation. Besides cell-mediated acute rejection, a "humoral" form exists which is more frequent in younger patients in the early postoperative period, and less likely to respond to the usual therapy. Cyclosporine therapy has deeply affected the clinical, laboratory and histological aspects of acute rejection. Though endomyocardial biopsy remains the most reliable diagnostic tool, other noninvasive procedures are of great value for a final diagnosis; among these are electrocardiography and two-dimensional echocardiography, which are the two elective techniques for post-transplantation follow-up in children. The laboratory and immunological assays, on the contrary, share a very low specificity. In conclusion, the diagnosis of acute rejection is still a clinical one, though supported by laboratory and histological evidence. In our experience, the natural evolution of many mild and mild-moderate rejection episodes toward regression does not support an excessive prophylaxis or an early treatment of symptom-free acute rejection. In addition, treatment of rejection must be personal and specific to each patient.
BACKGROUND: We performed a comparative study on Ca2+ release activity of the sarcoplasmic reticulum and calcium sensitivity of contractile apparatus of chemically skinned myocardial fibers obtained from four nonfailing human hearts and 13 excised hearts from patients with idiopathic dilated cardiomyopathy. METHODS AND RESULTS: Ca2+ sensitivity of contractile apparatus was studied by following the isometric tension developed by chemically skinned myocardial fibers challenged with solutions of decreasing pCa. Ca2+ release from sarcoplasmic reticulum was monitored indirectly by measurement of the isometric tension developed by skinned fibers challenged with caffeine. We observed no significant difference of Ca2+ sensitivity and cooperativity between normal myocardium (pCa50 = 6.00 +/- 0.05; Hill coefficient, nHill = 2.07 +/- 0.10) and dilated cardiomyopathy (pCa50 = 6.03 +/- 0.07; nHill = 2.72 +/- 0.30) when the fibers were stretched to 130% of the resting length. We also found that both in normal myocardium and dilated cardiomyopathy, stretching to 150% of the resting length increased the Ca2+ sensitivity of the contractile system; pCa50 = 6.21 +/- 0.01 and 6.13 +/- 0.04 in normal and dilated cardiomyopathy, respectively, whereas in dilated cardiomyopathy there was a decrease of Hill coefficient with stretching that was not observed in the control group. The caffeine threshold in idiopathic dilated cardiomyopathy was markedly increased compared with the control group, 1.94 +/- 0.27 mmol/l and 0.29 +/- 0.04 mmol/l caffeine, respectively, whereas there were no significant differences in the extent and rate of caffeine-induced Ca2+ release. CONCLUSIONS: These results indicate that in idiopathic dilated cardiomyopathy there is no alteration of contractile and regulatory proteins; on the contrary, the gating mechanism of the Ca2+ release channel of sarcoplasmic reticulum is abnormal, suggesting a possible involvement of the excitation-contraction coupling in the pathogenesis of this disease. It should also be taken into account, however, that the increased caffeine threshold in dilated cardiomyopathy would be a result of the enhanced resistance to the skinning procedure secondary to the modification of lipid species and/or content in sarcoplasmic reticulum membrane.
The shortage of ideal donor hearts has led to an increasing number of would-be heart transplant recipients who die while on the waiting list: an extension of the classical donor criteria seems necessary to expand the donor pool. In this paper, the major controversies on donor selection are presented, along with the clinical results obtained in cardiac transplantation with donor grafts not complying with standard criteria. The extension of donor age over 35 years is supported by the decreased incidence of coronary artery disease (CAD) in the Western world. In our experience, the number of donors over 40 years has increased steadily, without concomitant significant increase in postoperative short- and medium-term mortality after cardiac transplantation. The relative importance of CAD risk factors in the older heart donor is to be weighed out on a case-by-case basis. The performance of coronary angiography in 90% of the donor grafts over 50 years has led to more accurate selection. ECG minor alterations and ECHO diagnosed dyskynesias are of uncertain significance. Localized infection, transitory hypotension, brief cardiac arrest and thoracic trauma do not necessarily contraindicate heart donation. The importance of donor/recipient weight mismatch over 20% is critical only in face of high pulmonary vascular resistance. Prolonged dopamine infusion above 10 micrograms/kg/min may predict poorer function outcome. From our data, severe donor dysionemia may be very hazardous. In conclusion, our experience demonstrates that extended donor criteria do not compromise short- and medium-term clinical results of cardiac transplantation. Nevertheless, several controversial aspects of donor graft selection remain open.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
1. The effects of phosphate and protons on the mechanics and energetics of muscle contraction have been investigated using glycerinated rabbit psoas muscle. 2. Fibres were fully activated by addition of Ca2+ (pCa 4-5) at 10 degrees C. The velocities of contraction were measured in isotonic load clamps, and the velocities of unloaded fibres were measured by applying a series of step changes in fibre length. Fibre ATPase activity was monitored using an enzyme system to couple ADP production to reduced nicotinamide-adenine dinucleotide (NADH) and measuring the depletion of NADH by optical density. 3. At pH 7.0 and 3 mM-phosphate, isometric tension (P0) was 13.2 +/- 0.9 N/cm (mean +/- S.E.M., n = 10 observations), the maximum contraction velocity (Vmax) was 1.63 +/- 0.05 lengths/s (n = 5) and the ATPase activity was 1.27 +/- 0.12 s-1 myosin head-1 (n = 35). Increasing phosphate from 3 to 20 mM at pH 7.0 does not affect Vmax, causes a small decrease in the ATPase activity (15-20%) and decreases P0 by approximately 20%. Changing pH from 7 to 6 at 3 mM-phosphate decreases P0 by 45% and both Vmax and ATPase activity by 25-30%. The effects of changing both pH and phosphate were approximately additive for all parameters measured. The inhibition of these parameters by low pH and high concentration of phosphate was reversible. 4. The force-velocity relation was fitted by the Hill equation using a non-linear least-squares method. The value of the parameter which describes the curvature, a/P0, was 0.20. The curvature of the force-velocity relation was not changed by addition of phosphate or by changes in pH. 5. These data provide information on both the kinetics of the actomyosin interaction and on the process of muscle fatigue. The data are consistent with models of cross-bridge kinetics in which phosphate is released within the powerstroke in a step involving a rapid equilibrium between states. The inhibition by protons is more complex, and may involve less specific effects on protein structure. 6. During moderate fatigue of living skeletal muscle, MgATP concentration is known to remain approximately constant at 4 mM, phosphate to increase from 3 to 20 mM, and protons from 0.1 to 1 microM. The data suggest that much of the inhibition of P0 observed during moderate fatigue can be explained by the increased levels of phosphate and protons, and that much of the inhibition of fibre Vmax and ATPase activity can be explained by the increase in protons.