V.Paul Addonizio

Management of Left Ventricular Assist Device Infection With Heart Transplantation

BACKGROUNDnLeft ventricular assist devices (LVADs) are being used as bridges to heart transplantation (HT). Infection of the LVAD in this patient population represents a serious complication, as simple LVAD removal or delaying HT may result in death. To improve outcomes in this group of patients, we performed HT in the presence of LVAD infection.nnnMETHODSnEighteen patients underwent LVAD implantation followed by HT. Ten underwent HT in the absence of LVAD infection (group 1); and 8, in the presence of LVAD infection (group 2). All patients were treated similarly except for modification of immunosuppression in group 2 patients.nnnRESULTSnInfectious and noninfectious complications were equivalent between the two groups. There was no difference between groups in regard to intraoperative deaths (one versus none), long-term survival (8/10 versus 7/8), wound complications (three versus none), and mean length of hospital stay after HT (21 versus 26 days).nnnCONCLUSIONSnPatients with LVAD infection are too seriously ill to allow LVAD removal or delay of HT. Transplantation in the face of infection is an effective treatment option.

The effects of Carmeda Bioactive Surface on human blood components during simulated extracorporeal circulation.

Postoperative morbidity after cardiopulmonary bypass most commonly manifests as bleeding diatheses or pulmonary dysfunction. The pathophysiology has been attributed to the activation of cellular and humoral components of blood after contact with an artificial surface. Development of a surface that would be nonthrombogenic and also would constitute a less potent inflammatory stimulus would therefore be beneficial. In the following experiments, we evaluated the heparin-bonded Carmeda Bioactive Surface (Medtronics Cardiopulmonary, Anaheim, Calif.) in an in vitro model of extracorporeal circulation at standard-dose heparin (5 U/ml), to examine the effects of the surface treatment on activation of blood elements, and at reduced-dose heparin (1 U/ml), to determine whether surface-bound heparin would serve as an effective anticoagulant. During the initial recirculation period, platelet counts in the Carmeda (n = 12) circuits were preserved at both doses of heparin and compared with control values (n = 12): At 5 U/ml, control 36% +/- 4% (mean +/- standard error of the mean) versus Carmeda 81% +/- 5%; at 1 U/ml, 43% +/- 3% versus 61% +/- 10%, expressed as a percent of baseline at 30 minutes, p < 0.05. Furthermore, plasma levels of platelet factor 4 and beta-thromboglobulin were significantly reduced in the Carmeda circuits throughout the experiment: At heparin 5 U/ml, 2500 +/- 340 ng/ml versus 604 +/- 191 ng/ml; at 1 U/ml, 2933 +/- 275 ng/ml versus 577 +/- 164 ng/ml of platelet factor 4 at 2 hours (p < 0.05). The pattern of beta-thromboglobulin release was similar, with effects more pronounced at the lower dose of heparin. Surface modification also reduced leukocyte depletion (p < 0.05) and release of elastase at both concentrations of heparin (5 U/ml, 0.72 +/- 0.29 ng/ml versus 0.33 +/- 0.23 ng/ml; 1 U/ml, 0.85 +/- 0.08 ng/ml versus 0.20 +/- 0.05 ng/ml, at 2 hours, p < 0.05). Moreover, as heparin concentration was reduced, Carmeda surface treatment significantly decreased generation of C3a des Arg (1 U/ml, 14,410 +/- 3558 ng/ml versus 3053 +/- 1039 ng/ml at 2 hours, p < 0.05). Although heparin bonding was originally intended to obviate the need for systemic heparinization, Carmeda treatment did not reduce fibrinopeptide A generation at the lower dose of heparin. In summary, Carmeda treatment failed to exhibit anticoagulant efficacy in this model; however, the data suggest that surface modification may have a role in ameliorating the typical inflammatory response initiated by blood contact with an artificial surface.

Carotid endarterectomy in patients with heparin-induced platelet activation: comparative efficacy of aspirin and iloprost (ZK36374)

Patients with heparin-induced platelet activation who are reexposed to heparin may have recurrent thrombocytopenia, intravascular thrombosis, arterial emboli, or sudden death. To permit carotid endarterectomy in two patients with confirmed heparin-induced platelet activation, we compared the efficacies of aspirin and iloprost, a stable analogue of prostacyclin, in preventing heparin-induced platelet activation. In the first patient, although aspirin prevented both in vitro heparin-induced platelet aggregation (70% without and 7.5% with aspirin) and 14C serotonin release (48% without and 0% with aspirin), intraoperative administration of heparin resulted in an increase in plasma levels of platelet factor 4 from 8 to 260 ng/ml and beta-thromboglobulin levels from 29 to 39 ng/ml. In addition, the circulating platelet count decreased from 221,000 to 174,000 microliters, and 15% spontaneous platelet aggregation was observed. Fortunately, fibrinopeptide A levels remained less than 10 ng/ml intraoperatively, and no thrombotic complications occurred. In the second patient, aspirin did not prevent heparin-induced platelet aggregation in vitro (65% without and 41% with aspirin); however, iloprost (0.01 mumol/L) prevented both in vitro heparin-induced platelet aggregation (59.5% without and 0.0% with iloprost) and 14C serotonin release (56.7% without and 0.0% with iloprost). Therefore, a continuous infusion of iloprost was begun before administration of heparin and was continued until 20 minutes after reversal of heparin with protamine. After intraoperative administration of heparin, plasma levels of platelet factor 4 increased from 19 to 200 ng/ml, and beta-thromboglobulin levels increased from 56 to 76 ng/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Prediction of Homograft Aortic Valve Size by Transthoracic and Transesophageal Two-Dimensional Echocardiography.

To avoid the problem of patient valve mismatch we assessed the reliability of echocardiographic measurements in selecting an appropriate‐sized homograft aortic valve. Preoperative transthoracic echocardiography (TTE) was performed in 26 consecutive patients undergoing aortic valve replacement with a cryopreserved human homograft; 19 of the patients also had intraoperative transesophageal echocardiography (TTE). The diameters of left ventricular outflow tract (LVOT), aortic annulus, sinuses of Valsalva, and ascending aorta were measured by the same technique in all patients. There was a strong correlation between LVOT diameter measured by intraoperative TEE and homograft aortic valve size selected by the surgeon (r = 0.91, P < 0.001). A good correlation was also found between LVOT measured by preoperative TTE and the homograft valve size (r = 0.82, P = 0.001). The correlation between the homograft aortic valve size and the diameter of aortic annulus was less optimal; the correlation was poor for the diameter of aorta measured at the level of the sinuses of Valsalva and ascending aorta. Measurement of the LVOT diameter by intraoperative TEE and preoperative TTE is reliable and clinically useful for the preparation of homograft aortic valves and selection of proper size, particularly in those patients undergoing repeat aortic valve replacement, with heavily calcified aortic valve or with ascending aortic aneurysm.

Early fungal endocarditis in homograft recipients

Retrospective analysis of 200 homograft valve recipients at our institution revealed two cases of fungal endocarditis. Pathogenesis appears to be related to either recipient seeding in one elderly immunocompromised patient or a previously contaminated donor valve implanted in an otherwise healthy recipient. Therefore, our experience underscores the need for both meticulous prevention of fungal infection preoperatively in the recipient and elimination of previously contaminated homograft valves from the donor pool.

969-99 Biocompatible Mechanical Left Ventricular Support: Potential Alternative to Transplantation

Use of mechanical circulatory support has been limited by its associated bleeding and thrombotic complications. Blood contact with an artificial surface results in a well-deined pattern of hematologic alterations. The TCI HeartMate® left ventricular assist device (LVAD) is an implantable circulatory support pump currently used as a bridge to transplantation. Its textured blood contacting surfaces result in a formation of an adherent pseudoneointimal lining which eliminates the direct interaction of blood elements with the artificial surface. To determine if this biological lining could mitigate the stereotypical blood-synthetic surface interactions, we studied eight patients who underwent implantation at our institution over a 10 month period from 5/93 to 3/94. Seven of the 8 patients were bridged to transplantation. Three patients were transplanted within 10 days and one month data could not be obtained. Hemodynamic and hemostatic parameters (meanxa0±xa0sd) were studied as follows: Pre-implant POD 7 POD 28 Cardiac index (I/min/m2) 1.8xa0±xa00.7 3.2xa0±xa00.4 3.1xa0±xa00.5 Systolic BP (mmHg) 759xa0±xa06.8 125.8xa0±xa09.7 130.4xa0±xa08.1 Hemoglobin (mg/dl) 7.4xa0±xa01.8 8.2xa0±xa01.6 9.6xa0±xa02.0 Plasma free hemoglobin (mg/dl) 15.4±1.7 6.4xa0±xa02.3 6.8xa0±xa01.9 Prothrombin time (sec) 14.2xa0±xa01.1 13.4xa0±xa00.7 13.3xa0±xa00.7 Partial thromboplastin time (sec) 56.7xa0±xa015.9 31.8xa0±xa04.8 37.6xa0±xa011.9 Platelet count (× 103lcu mm) 250xa0±xa081 269xa0±xa063 325xa0±xa037 In vitro platelet reactivity to the agonist ADP remained normal pre and post implantation. Average perioperative blood requirements included PRBC, 3.3xa0±xa01.3 units; platelets, 2.3xa0±xa04.5 units; fresh frozen plasma, 2xa0±xa01.9 units. No blood products were required after postoperative day 2. We conclude that TCI LVAD support improves hemodynamics and can bridge patients in pre-implant cardiogenic shock to transplantation. Furthermore, no red cell destruction or hemostatic and thrombotic complications were observed despite one month of support without anticoagulation therapy. Therefore, as the donor shortage continues, LVADs with biocompatible surfaces may provide an alternative to cardiac transplantation.

733-1 Improved Early Myocardial Function with Bicaval Versus Standard Orthotopic Heart Transplantation

The technique of standard orthotopic heart transplantation (SOHT) has changed little since it was first described by Shumway and Lower. SOHT requires anastomoses between the posterior remnants of the recipient left and right atria and the donor heart. Although many transplants have been performed with excellent results. echocardiographic studies have shown that the large capacitance chambers created by combining the recipient and donor atria prevent the augmentation of myocardial function by properly timed atrial contraction. If the recipient and donor atria are synchronized. mitral valve flow velocity and hemodynamics are improved. Bicaval OHT (BOHT) involves complete excision of the right atrium and near total excision of the left atrium in recipients. The donor right atrium is left intact and bicaval anastomoses performed; the left atrium is anastomosed back to the pulmonary veins. We studied the effect of both techniques on immediate post-transplantation myocardial function. Twenty four transplants between 9/93 to 3/94 were studied; twelve patients received SOHT (group A) and twelve consecutive subsequent patients received BOHT (group B). Inotropes were adjusted to maintain HR g 100 bpm, CI g 2.5 I/min/m2and mean BP g 75 mmHg. All patients received standard triple immunosuppression. The two groups were similar with regard to 1) recipient weight. sex. age, pretransplant hemodynamics; 2) donor ischemic times, preharvest donor inotropes. donor 1recipient weight ratios; 3) post transplantation hemodynamics and dopamine requirements. Significant differences at pxa0lxa00.05 include (group A vs. group B): time for implantation (38.6xa0±xa010.6 vs. 50.2xa0±xa012.2 minutes), isuprel requirements at POD 1 (1.2xa0±xa00.2 vs. 0.2xa0±xa00.1 μg/min), epinephrine requirements at POD 1 (2.2xa0±xa00.3 vs. 0.4xa0±xa00 1 μg/min), need for temporary external pacing before POD 7 (67% vs. 4%). intrinsic heart rate at one week (67.4xa0±xa010.2 vs. 85.4xa0±xa012.1 bpm) and incidence of echocardiographic tricuspid regurgitation at one week (50% vs. 0%). All patients survived. This study demonstrates similar hemodynamics with significantly less inotropic requirements. especially of epinephrine and isupre!. Furthermore. chronotropy is improved and tricuspid regurgitation is eliminated. Although BOHT adds an anastomosis and requires longer for completion. the improved myocardial and sinus node function suggest that it can be considered a superior alternative to SOHT.