Relationship between early diastolic intraventricular pressure gradients, an index of elastic recoil, and improvements in systolic and diastolic function.

BACKGROUND: Early diastolic intraventricular pressure gradients (IVPGs) have been proposed to relate to left ventricular (LV) elastic recoil and early ventricular "suction." Animal studies have demonstrated relationships between IVPGs and systolic and diastolic indices during acute ischemia. However, data on the effects of improvements in LV function in humans and the relationship to IVPGs are lacking. METHODS AND RESULTS: Eight patients undergoing CABG and/or infarct exclusion surgery had a triple-sensor high-fidelity catheter placed across the mitral valve intraoperatively for simultaneous recording of left atrial (LA), basal LV, and apical LV pressures. Hemodynamic data obtained before bypass were compared with those with similar LA pressures and heart rates obtained after bypass. From each LV waveform, the time constant of LV relaxation (tau), +dP/dt(max), and -dP/dt(max) were determined. Transesophageal echocardiography was used to determined end-diastolic (EDV) and end-systolic (ESV) volumes and ejection fractions (EF). At similar LA pressures and heart rates, IVPG increased after bypass (before bypass 1.64+/-0.79 mm Hg; after bypass 2.67+/-1.25 mm Hg; P<0.01). Significant improvements were observed in ESV, as well as in apical and basal +dP/dt(max), -dP/dt(max), and tau (each P<0.05). Overall, IVPGs correlated inversely with both ESV (IVPG=-0.027[ESV]+3.46, r=-0.64) and EDV (IVPG=-0.027[EDV]+4.30, r=-0.70). Improvements in IVPGs correlated with improvements in apical tau (Deltatau =5.93[DeltaIVPG]+4.76, r=0.91) and basal tau (Deltatau =2.41[DeltaIVPG]+5.13, r=-0.67). Relative changes in IVPGs correlated with changes in ESV (DeltaESV=-0.97[%DeltaIVPG]+23.34, r=-0.79), EDV (DeltaEDV=-1.16[%DeltaIVPG]+34.92, r=-0.84), and EF (DeltaEF=0.38[%DeltaIVPG]-8.39, r=0.85). CONCLUSIONS: Improvements in LV function also increase IVPGs. These changes in IVPGs, suggestive of increases in LV suction and elastic recoil, correlate directly with improvements in LV relaxation and ESV.

Ascorbate attenuates atrial pacing-induced peroxynitrite formation and electrical remodeling and decreases the incidence of postoperative atrial fibrillation.

Atrial fibrillation (AF), the most common chronic arrhythmia, increases the risk of stroke and is an independent predictor of mortality. Available pharmacological treatments have limited efficacy. Once initiated, AF tends to self-perpetuate, owing in part to electrophysiological remodeling in the atria; however, the fundamental mechanisms underlying this process are still unclear. We have recently demonstrated that chronic human AF is associated with increased atrial oxidative stress and peroxynitrite formation; we have now tested the hypothesis that these events participate in both pacing-induced atrial electrophysiological remodeling and in the occurrence of AF following cardiac surgery. In chronically instrumented dogs, we found that rapid (400 min(-1)) atrial pacing was associated with attenuation of the atrial effective refractory period (ERP). Treatment with ascorbate, an antioxidant and peroxynitrite decomposition catalyst, did not directly modify the ERP, but attenuated the pacing-induced atrial ERP shortening following 24 to 48 hours of pacing. Biochemical studies revealed that pacing was associated with decreased tissue ascorbate levels and increased protein nitration (a biomarker of peroxynitrite formation). Oral ascorbate supplementation attenuated both of these changes. To evaluate the clinical significance of these observations, supplemental ascorbate was given to 43 patients before, and for 5 days following, cardiac bypass graft surgery. Patients receiving ascorbate had a 16.3% incidence of postoperative AF, compared with 34.9% in control subjects. In combination, these studies suggest that oxidative stress underlies early atrial electrophysiological remodeling and offer novel insight into the etiology and potential treatment of an enigmatic and difficult to control arrhythmia. The full text of this article is available at http://www.circresaha.org.

Clinical experience with long-term use of implantable left ventricular assist devices: indications, implantation, and outcomes.

We describe our clinical experience with 205 implantable left ventricular assist devices at the Cleveland Clinic between December 1991 and January 2000, along with manufacturers' data submitted to the Food and Drug Administration. In patients with end-stage cardiac failure who are suitable candidates for transplantation, these devices serve as excellent bridges to transplantation. Recent modifications have increased pump reliability and reduced thromboembolic rates. The vented electric HeartMate (Thermocardiosystems Inc, Woburn, MA) and the Novacor (Baxter-Novacor, Oakland, CA) left ventricular assist systems allow patients to be discharged from the hospital while awaiting a donor heart. Experience with long-term support is providing insights into permanent implantation of these devices as destination therapy. Although infection remains a major impediment to long-term support, patient-pump interactions leading to changes in the coagulation and immune systems are being recognized, and these interactions may have important implications with respect to thromboembolism, infection, and sensitization to human leukocyte antigens (HLAs). Better understanding of these factors may eventually lead to the development of permanently implantable pumps as an alternative to transplantation.

Fibrin glue for the treatment of persistent lymphatic drainage.

A 7-year-old girl underwent resection of an abdominal wall lymphangiomatous tumor. Postoperative serous drainage, up to 300 mL per day, developed despite application of external pressure to the wound. Thirty-three days after the initial procedure, fibrin glue was applied to the draining tract. Concentrated fibrinogen was prepared from one unit of blood donated by the patient's mother. Ten milliliters fibrinogen and 10 mL thrombin (1,000 U/mL) were injected simultaneously through the wound drain as it was slowly removed, and pressure was reapplied for 48 hours. No further drainage occurred, and at 2- and 14-week follow-up examinations the wound had healed normally without reaccumulation of fluid. Fibrin glue successfully sealed this persistently draining abdominal wall tract. It is a painless, safe, and effective biologic sealant, and when prepared from homologous plasma it carries a low risk of virus transmission.

Effect of blood conservation efforts in cardiac operations at the Mayo Clinic.

In a retrospective study of 388 patients who had undergone cardiac operations at our institution during two time periods-before (1982) and after (1984) introduction of autologous transfusion-we analyzed the effect of blood conservation efforts and autologous transfusion on blood usage, postoperative complications, and duration of hospitalization. Cell salvage techniques resulted in a significant reduction (P less than 0.0001) in use of not only homologous blood (from a mean of 9.6 units per patient in 1982 to 3.2 units in 1984) but also fresh-frozen plasma and platelet concentrates. We found no significant difference in morbidity or mortality for the two study periods. Although the mean duration of hospitalization decreased from 11.7 days in 1982 to 9.6 days in 1984, this change was probably related to factors other than the introduction of blood conservation efforts. Thus, techniques used to decrease the amount of blood replacement needed for cardiac surgical procedures are beneficial.