Implantation of Cardio West Total Artificial Heart for Irreversible Acute Myocardial Infarction Shock

Patients who develop cardiogenic shock after acute myocardial infarction have a very high mortality rate despite early reperfusion therapy. Hemodynamic stabilization can often only be achieved by implanting a mechanical circulatory support system. When, in cases representing expansive myocardial impairment without any chance of recovery, pharmacological therapy and the use of percutaneous assist devices have failed, the implantation of a total artificial heart is indicated. We report our first experiences with this extensive and innovative method of managing irreversible cardiogenic shock patients. The CardioWest total artificial heart was implanted in 5 patients (male; mean age, 50 years). All patients were in irreversible cardiogenic shock despite maximum dosages of catecholamines, an intra-aortic balloon pump and/or a femoro-femoral bypass. In all patients early reperfusion therapy was performed. After implantation of the Cardio West system, all dysfunctional organ systems rapidly recovered in all patients. Four of 5 patients underwent successful heart transplantation after a mean support time of 156 days. One patient died because of enterocolic necroses caused by an embolic event after termination of dicumarol therapy. In summary, our first experiences justify this extensive management in young patients who would otherwise have died within a few hours.

A Risk Score to Predict 30-Day Mortality in Patients with Intra-Aortic Balloon Pump Implantation

BACKGROUND

Several risk factors for early mortality after intra-aortic balloon pump (IABP) implantation have been described.

METHODS

We performed a retrospective analysis in 120 patients receiving peri- or postoperative IABP support. Univariate and multivariate analyses were carried out to assess variables potentially influencing 30-day mortality in order to develop a risk score for the prognosis of survival and for the decision on optimal patient-specific treatment.

RESULTS

The 4 parameters (mean arterial pressure, adrenaline dose, central venous pressure, and blood lactate concentrations) at 6 hours of IABP use were independently related to 30-day mortality. They were used to develop a risk score (0 - 4 points). With this score, patients who scored 3 or 4 points had no probability of surviving, whereas patients with a score of zero had a probability of 84.4 %. A prospectively screened cohort of 145 patients confirmed the reliability of our risk score.

CONCLUSIONS

Our data demonstrate that a score can predict 30-day mortality in patients with IABP implantation. Such a score can be useful to find out whether or not ECMO/VAD implantation is necessary.

IgG classification of anti-PF4/heparin antibodies to identify patients with heparin-induced thrombocytopenia during mechanical circulatory support

Commercial immunoassays frequently detect anti-PF4/heparin antibodies during mechanical circulatory support (MCS), but only a small minority of patients develops heparin-induced thrombocytopenia (HIT). Whereas platelet functional tests can distinguish between platelet-activating and non-platelet-activating antibodies, commercial PF4-dependent immunoassays do not. Between 2003 and 2004, 113 patients were placed on MCS. Blood samples were obtained on postimplant day 5-7 for analyses by antibody assays and the functional heparin-induced platelet activation (HIPA) assay. Three distinct groups of patient sera were identified: platelet-activating anti-PF4/heparin antibodies (n = 10), non-platelet-activating anti-PF4/heparin antibodies (n = 53), and anti-PF4/heparin antibody negative (n = 50). Patients with platelet-activating antibodies had the highest risk for thromboembolic events (P < 0.005), whereas those with non-platelet-activating antibodies did not differ from antibody negative patients (P = 0.369). The enzyme-immunoassay and column agglutination assays, which cover all immunoglobulin classes, demonstrated adequate sensitivity and negative predictive value; yet, both lacked specificity with respect to the platelet-activating antibodies. If all antibody positive patients were further classified by an IgG-specific anti-PF4/heparin enzyme-immuno assay, specificity for platelet-activating antibodies increased. Whereas IgG-specific optical density (OD) values below 1.0 were likely for non-platelet-activating anti-PF4/heparin antibodies, higher values were progressively predictive for pathogenic platelet activation. The probability of the development of clinical HIT also increased steeply. In conclusion, platelet-activating anti-PF4/heparin antibodies are relatively common (about 9%) in patients on MCS and are associated with significantly higher thrombotic event rates. Low IgG-specific OD values (< 1.0) in the enzyme-immunoassay indicate low likelihood for the presence of platelet-activating antibodies. These results justify further validation so that anticoagulation during MCS becomes safer and adequate.

Total artificial heart-implantation technique using the CardioWest or the Thoratec system

Total artificial heart is a safe and efficient bridge for patients with terminal congestive heart failure awaiting cardiac transplantation. The implantation of the CardioWest total artificial heart has become an accepted therapeutic option in critically ill patients who have irreversible biventricular failure and are candidates for cardiac transplantation. Because of anatomical limitations in smaller patients (women, adolescents) implantation of the CardioWest system might be impossible. In these cases we have implanted the paracorporeal Thoratec device in a modified technique as a total artificial heart.

A multidisciplinary network to save the lives of severe, persistent cardiogenic shock patients

BACKGROUND

Severe, persistent cardiogenic shock is associated with very high morbidity and lethality. We therefore tried to improve the outcome of these patients using a network between local hospitals and a specialized heart center that has facilities for transplantation and ventricular assist device (VAD) implantation.

METHODS

Between 1998 and 2000, 50 patients, who were in cardiogenic shock (mean age 49 years, SD 14) despite high doses of at least three inotropic agents, were admitted to our specialized heart center. During the first 12 hours, we tried to stabilize the patient's condition, to reduce inotropic support agents, and to keep cardiac index above 2.4 L.min(-1).m(-2). According to this strategy, patients were allocated to medical treatment only, emergency VAD therapy, urgent VAD implantation, or heart transplantation. To assess variables potentially influencing patients' outcome, we performed univariate and multivariate analyses.

RESULTS

Early in-hospital mortality was 36% and late mortality was 10%. Overall survival at 1, 6, and 12 months of follow-up was 70%, 56%, and 52%, respectively. Even when the heart transplant patients were excluded, overall 12-months survival after cardiogenic shock was still 50%. Higher age, and the absence of sinus rhythm were the only independent risk factors for 12-month mortality.

CONCLUSIONS

Our data show that a network between cardiology departments of local hospitals and specialized heart centers can be life-saving for severe, persistent cardiogenic shock patients.

Low-dose international normalized ratio self-management: a promising tool to achieve low complication rates after mechanical heart valve replacement

BACKGROUND

International normalized ratio (INR) self-management can significantly reduce INR fluctuations, bleeding, and thromboembolic events compared with INR control managed by general practitioners. However, even patients with INR self-management may have an increased risk of bleeding if their INR value is above 3.5. This study evaluated the compliance, clinical complications, and survival of patients after mechanical heart valve replacement with low-dose INR self-management compared with conventional-dose anticoagulation.

METHODS

Group 1 (n = 908) received low-dose anticoagulation with a target INR range of 1.8 to 2.8 for aortic valve replacement and 2.5 to 3.5 for mitral or double valve replacement. Group 2 (n = 910) received conventional-dose anticoagulation with a target INR range of 2.5 to 4.5 for all heart valve prostheses.

RESULTS

In groups 1 and 2, 76% and 75% of INR values, respectively, were in the target range. Results did not differ according to schooling and age. The rate of thromboembolic events per patient year was 0.18% in group 1 and 0.40% in group 2 (p = 0.210). The rate of bleeding complications was 0.74% for group 1 and 1.20% for group 2 (p = 0.502). In most patients with clinically relevant bleeding, these complications occurred although their measured INR values were below 3.5. The survival rate did not differ between the study groups (p = 0.495).

CONCLUSIONS

Low-dose INR self-management is a promising tool to achieve low hemorrhagic complications without increasing the risk of thromboembolic complications. INR self-management is applicable for all patients in whom permanent anticoagulation therapy is indicated. Even INR values below 3.5 can bear the risk of bleeding complications.

Heparin-induced thrombocytopenia in patients receiving mechanical circulatory support

OBJECTIVES

Patients receiving mechanical circulatory support are at risk for the development of heparin-induced thrombocytopenia due to the prolonged postoperative use of heparin. We evaluated their antibody status and outcome.

METHODS

Between 2003 and 2004, 115 patients received mechanical circulatory support for more than 5 days. Blood samples from postoperative day 7 were retrospectively analyzed for anti-platelet factor 4/heparin antibodies and heparin-induced platelet activation.

RESULTS

Overall, 12 (10.6%) patients had heparin-induced thrombocytopenia as defined by in vitro platelet activation, 28 (24.8%) had nonactivating antibodies, and 73 (64.6%) were classified as negative for antibodies. Patients positive for heparin-induced thrombocytopenia had the highest levels of anti-platelet factor 4/heparin immunoglobulin G antibodies. Freedom from thromboembolism was 33%, 33%, and 16% at 1, 3, and 6 months for positive patients, 77%, 68%, and 55% for negative patients (P < .001), and 70%, 53%, and 53% for patients with nonactivating antibodies (P = .068), respectively. The relative risk for thromboembolism in antibody positive patients peaked in the first month of support (odds ratio 7.46, P = .002). Independent risk factors for thromboembolic events included higher anti-platelet factor 4/heparin antibody titers, female gender, and higher fibrinogen levels.

CONCLUSION

Heparin-induced thrombocytopenia was more prevalent in patients receiving mechanical circulatory support than in other cardiac patients. Frequent antibody screening is recommended due to the increased risk of thromboembolism. Heparin alternatives should be subjected to clinical trials in these high-risk patients.

Triple Bridge-to-Transplant in a Case of Giant Cell Myocarditis Complicated by Human Leukocyte Antigen Sensitization and Heparin-Induced Thrombocytopenia Type II

Bridge-to-bridge experience has documented the feasibility of a switch from short-term to long-term mechanical circulatory support until heart transplant. We describe a case of irreversible cardiogenic shock due to giant cell myocarditis treated consecutively with extracorporal membrane oxygenation, bi-ventricular assist device, and total artificial heart. The postoperative course was complicated by human leukocyte antigen sensitization and heparin-induced thrombocytopenia type II. Our patient successfully underwent heart transplant after 10 months of support and was discharged in good condition. This case illustrates suitable device selection for myocarditis and represents two treatable immunological complications.