Engineering transcatheter aortic valve devices: a surgeon's perspective.

In recent years transcatheter approaches to treat heart valve disease have played an increasingly important role. This has been especially true for aortic stenosis, with two valves commercially available in Europe and several others under investigation in man. These least invasive therapies have expanded treatment options for the highest surgical risk patients, but there are fundamental differences from conventional surgical repair that warrant further investigation. This manuscript reviews the rapidly evolving field of transcatheter aortic valve intervention from the clinician's perspective. Anatomic, pathologic, and physiologic issues posed by the disease process are first reviewed. Device and design challenges to this new therapy are then addressed. Finally, newer devices and transcatheter approaches to other valve disease are briefly reviewed. The understanding that can come from an engineering approach to address these multiple issues should further improve outcomes and advance development of next-generation devices.

Renal grafts from elderly donors: histological studies and long-term results.

To satisfy the increasing requests for renal grafts, elderly donors are increasingly accepted for kidney transplant at many centers. The main unresolved question is the long-term effect on graft survival of potential histological lesions due to donor age. We present a prospective histological study performed from January 1997 to December 2001 on 184 consecutively transplanted renal grafts in which the only criterion for graft acceptance was a normal value of serum creatinine upon admission to the intensive care unit independent of donor age. At the end of the study, 57 recipients (31%) of mean age 55 years (range 39 to 67 years) received a renal graft from donors aged more than 60 years (mean age 66 years; range 60 to 75 years), this cohort denoted as older donor kidney transplant group (ODKTG) and 127 recipients (69%) with a mean age of 49 years (range 21 to 63 years) received a renal graft from donors whose age was lower than 60 years (mean age 49 years; range 16 to 59 years), a cohort denoted as the younger donor kidney transplant group (YDKTG). The two groups were comparable for time of dialysis, cold ischemia time, immunosuppression therapy, grading of histological damage. At the end of the study with a mean follow-up of 5.6 years (range 3.5 to 7.5 years), primary graft nonfunction and delayed graft function were significantly more represented in the ODKTG than the YDKTG. Cumulative patient and graft survival was 84.3% and 79.4% in the ODKTG, respectively, and 93.8% and 85.9% in the YDKTG, respectively (P = NS). Cumulative serum creatinine values were 1.98 mg/100 mL in ODKTG and 1.65 mg/100 mL in YDKTG (P = NS). In conclusion, renal grafts from older donors presented histological damage comparable to that seen among renal grafts from younger donors.

Early and late rejection and HLA sensitization at the time of heart transplantation in patients bridged with left ventricular assist devices.

Over the years, the frequency of heart transplant candidates with HLA sensitization has increased as a result of the number of patients bridged to transplant using left ventricular assist devices (LVAD). Here we have examined 119 patients who were bridged to transplant with LVAD for a relationship between HLA antibodies and early (30 days) and late (2 years or more) rejection, as evidenced by endomyocardial biopsies. Both cytotoxic panel-reactive antibody reactions against a panel of T lymphocytes (T-PRA) and the percentage of transplants that occurred across a positive class I flow cross-match were examined. Biopsies were scored using ISHLT criteria. At 30 days, patients who had a biopsy grade of 0 had a mean T-PRA at transplant of 2.2%, while the mean PRAs of the other biopsy grades were significantly higher (P < .001). A similar pattern was seen with the highest biopsy results at 2 years or later (P < .001). None of the patients who had a grade 0 biopsy at 30 days posttransplant had a positive flow cytometry class I cross-match (P = .02), although the same pattern did not occur later due to a small number of patients (n = 3) who had negative biopsies. Thus, when biopsy results were examined early or late posttransplant, patients with negative biopsy results tended to have less HLA sensitization. While the methods of HLA sensitization involve humoral responses, more aggressive immunosuppression might be warranted to attempt to reduce cellular rejection posttransplant if HLA class I antibodies are present at the time of transplant.

[Evaluation of renal function during orthotopic liver transplantation]. / Valutazione della funzione renale in corso di trapianto ortotopico di fegato.

BACKGROUND: Orthotopic liver transplantation (OLI) is a recognised means of therapy for endstage liver failure (ESLF). Both the preoperative alterations of renal function, closely correlated with the ESLF, and the frequent and abrupt changes of circulating blood volumes occurring during the various phases of OLT are able to significantly alter renal function during the perioperative period. METHODS: In order to define the specific changes of renal function during the various phases of OLT, six postnecrotic cirrhotic patients undergoing their first OLT entered a prospective study protocol. All the patients had standard and anesthetic techniques including the venovenous bypass (VVBP) during the anhepatic phase. At standard intervals (baseline, during hepatic dissection, during the anhepatic phase, following reperfusion, at the end of surgery) together with complete hemodynamic and metabolic profiles, arterial blood and urine samples were obtained to determine electrolytes and creatinine concentrations, blood levels of atrial natriuretic factor, aldosterone and renin activity. Using standard formulas creatinine clearance (Ccreat) and Na absolute and fractional excretions (FeNa%) were calculated. RESULTS: Major changes in the hemodynamic profile occurred during the anhepatic phase in spite of the use of the VVBP (reduced cardiac index, reduced pulmonary wedge pressure, increased systemic vascular resistances). Concomitantly a significant decrease in Ccreat (-67%) and in urinary output, was present while aldosterone and renin activity increased. The changes in Ccreat persisted at the end of surgery in spite of the optimal hemodynamic profile. Aldosterone and renin activity returned to values close to baseline at the end of surgery. CONCLUSIONS: From these data it is possible to conclude that renal function markedly deteriorates during OLT and it has to be considered at increased risk in the immediate postoperative period. The use of VVBP does not seem to prevent the intraoperative renal impairment.

Lactate blood levels in the perioperative period of orthotopic liver transplantation.

To investigate whether early postoperative changes in blood lactate concentration indicate the functional recovery of the newly grafted liver, changes in oxygen supply, oxygen consumption, acid-base equilibrium, and blood lactate concentrations were prospectively studied in a group of 53 postnecrotic cirrhotic patients during the various phases of orthotopic liver transplantation (preanhepatic, anhepatic, neohepatic) and for the first 48 h following reperfusion. The patients were divided into two groups according to the quality of the early graft function, as indicated by alanine aminotransferase, bile flow, and prothrombin activity: group A (49 patients), good immediate graft function and group B (4 patients), immediate graft non-function. Lactate levels rose in the same manner during the preanhepatic and anhepatic stages and peaked after revascularization of the graft. Following reperfusion, however, distinctly different blood lactate profiles were recorded in the two groups of patients. A fall in lactate concentration was recorded in group A patients, whereas a continuous rise occurred in group B patients: the difference becoming significant by the end of surgery (P < or = 0.05). During the first 48 h following revascularization of the graft, opposite trends in lactate concentration, bile flow, alanine aminotransferase, and prothrombin activity were evident in the two groups of patients: 24 h after reperfusion, lactate levels were below 2 mmol/l in 47 of 49 patients from group A, while they plateaued above 4 mmol/l in all patients from group B. Group A patients had lower alanine aminotransferase levels (P < or = 0.001), higher prothrombin activity, (P < or = 0.01), and greater bile flow (P < or = 0.02). If validated in larger series, the blood lactate profile, probably more than the absolute level, appears to be a useful indicator of the early recovery of liver metabolic capacities in the immediate postoperative period of orthotopic liver transplantation.

[The genetic influence on the labile pseudo-ischemic T-wave (author's transl)]. / Studio sul condizionamento genetico del quadro elettrocardiografico di onda T labile pseudo-ischemica.

After the demonstrated familial incidence of the "labile pseudo-ischemic T-wave" patterns, a research has been carried on in order to ascertain the possible genetic conditioning of the anomaly. The analysis of the pattern of the families, formed starting from the subjects carrier of the above-mentioned pattern, carried on with the Haldane sibships method corrected with that proposed by Lejeune, leads to affirm that the models of hereditary transmission able of explaining the found out distributions are of a not simple recessive type. The distribution of frequence of the subjects by "aplotype HLA" does not permit to settle a reliable correlation between the considerated electrocardiographic anomaly and the aplotype, at least as far as the number of the examined cases is concerned.