Management of Prosthetic Valves during Ventricular Assist Device Implantation

Abstract Background: An increasing number of patients requiring ventricular assist devices (VAD) have had previous valvular corrections, including valve repair and valve replacement with mechanical or bioprosthetic valves. The operative and peri‐operative management of these patients has been varied. Methods: A retrospective study of VADs between January 1994 and June 2008 revealed 10 patients with previous prosthetic valves requiring management during and after VAD placement. Three patients were supported postcardiotomy after valve surgery. Two patients were supported due to cardiogenic shock postoperatively. Four patients were supported as a bridge to transplantation. One patient was supported as a destination therapy (DT). Results: The mitral, valve was left untreated during VAD implantation regardless of valve repair or replacement. For aortic valves, the mechanical aortic valve was replaced with tissue valve in two patients and left untreated in one case. One patient had tricuspid valve repair previously and was left untouched. All patients with prosthetic valves in aortic, mitral and tricuspid position during VAD support received anticoagulation therapy. There were four deaths, and four went on to transplantation. One patient was weaned from VAD and discharged from the hospital. One patient received HeartMate I as DT. The most common causes of death were multisystem organ failure (MSOF) and sepsis. One patient had a thromboembolic event. Conclusions: The survival rate of 60% is encouraging when compared to overall survival rates. The most common cause of death was MSOF. Patients with prosthetic valves may be safely managed during VAD support. (J Card Surg 2010;25:601‐605)     

心脏瓣膜术后心室辅助治疗

目的 总结瓣膜病变术后重症心衰病人置入心室辅助(VADs)装置时,心脏瓣膜或人工瓣膜处理方法及围术期抗凝管理的经验.方法 回顾1994年1月到2008年6月,宾夕法尼亚大学附属医院心脏中心157例置入VADs病人中,10例为瓣膜术后重症心衰者.对于二尖瓣和三尖瓣病变,无论成形或置换,置入VADs时均未处理原瓣膜或人工瓣膜(环).5例主动脉瓣病变病例置入VADs时,2例用生物瓣膜取代了原机械瓣膜,1例未处理原来生物瓣膜,1例未处理原机械瓣膜,1例取出机械瓣膜,用牛心包封闭主动脉根部.结果 所有病人置入VADs术后应用抗凝治疗.10例病人中,停VAD出院和VAD姑息治疗各1例;转心脏移植4例;4例死亡,3例为多器官衰竭,1例为血栓栓塞事件.结论 瓣膜病变术后置入VADs总的生存率是60%,与非瓣膜病心衰病人置入VADs相比,未增加手术风险.

Abstract：

Objective An increasing number of patients requiring ventricular assist devices (VAD) have had previous valvular corrections,including valve repair,and valve replacement with mechanical or bioprosthetic valves.The operative and peri-operative management of these patients has been varied.Methods A retrospective study of VADs between Jan 1994 and June 2008 revealed 10 patients with previous prosthetic valves requiring management during and after VAD placement.Three patients were supported post-cardiotomy after valve surgery.Two patients were supported due to cardiogenic shock postopera-tively.Four patients were supported as a bridge to transplantation.One patient was supported as a destination therapy.Results The mitral valve was left untreated during VAD implantation regardless of valve repair or replacement.For aortic valves,the mechanical aortic valve was replaced with tissue valve in two patients and left untreated in one case.One patient had tricuspid valve repair previously and was left untouched.All patients with prosthetic valves in aortic,mitral and tricuspid position during VAD support received anticoagulation therapy.There were 4 deaths,and 4 went on to transplantation.One patient weaned from VAD and discharge from hospital.One patient received HeartMate Ⅰ as destination therapy.The most common causes of death were multisystem organ failure and sepsis.One patient had a thromboembolic event.Conclusion The survival rate of 60% is encouraging when compared to overall survival rates.The most common cause of death was multisystem organ failure.Patients with prosthetic valves may be safely managed during VAD support.     

Ventricular assist device support in patients with mechanical heart valves

Background. Due to potential thromboembolic complications, mechanical valves within the native heart are often considered contraindications to ventricular assist device (VAD) support.

Methods. A retrospective review of VAD cases between June 1982 and March 1998 showed 8 patients with mechanical valves who were supported with Thoratec (Pleasanton, CA) VADs.

Results. There were 6 males and 2 females ranging in age from 20 to 69 years (mean 49.8 ± 5.6). Four patients were supported when they could not be weaned from cardiopulmonary bypass after reparative procedures and were thought to have reversible injuries. Four patients were supported as a bridge-to-cardiac transplantation. Two patients had mechanical mitral valves, 2 had aortic valve replacements, 1 had an aortic homograft and mechanical mitral valve, 2 had mechanical aortic and mitral prosthesis, and 1 patient had aortic, mitral, and triscupid valves. The types of valvular prostheses were St. Jude (5 patients) and Bjork-Shiley (3 patients). Duration of support ranged from 3.0 to 150 days (mean 34 days). Four patients were supported with biventricular assist devices and 4 had left VADs. Dextran and intravenous heparin anticoagulation were used in the shorter duration patients, with warfarin being used in the bridge patients. One patient received warfarin and aspirin. At the time of autopsy or device removal, only 1 of the 12 mechanical intracardiac valves showed any evidence of thrombosis, including the aortic valves in 2 patients supported for 2 and 5 months. There were no clinical thromboembolic events. Four patients (50%) were discharged (1 weaned, 3 transplanted).

Conclusions. The 50% (4 of 8) survival rate compares favorably with the 44% (41 of 92) overall survival rate for our Thoratec patients (bridge plus recovery) who did not have mechanical prosthetic valves. These data suggest that patients with mechanical intracardiac valves can be supported for short durations with some additional risk, which is yet to be determined.     

Successful replacement of malfunctioning TCI HeartMate LVAD with DeBakey LVAD as a bridge to heart transplantation

Congestive heart failure is the leading cause of hospitalization and death in the developed world and affects about 0.4-2% of the adult population [Ann Thorac Surg 1999;68:637-40]. Heart transplantation remains the most effective therapy for end-stage heart disease, but the shortage of donors has led to increasing interest in other surgical options, especially ventricular assist devices (VAD). Several VADs are available to bridge patients to transplantation [N Engl J Med 2001;345:1435-43], including pulsatile devices like the HeartMate (HeartMate, Thoratec, Pleasanton, CA) and Novacor (World Heart, Netherlands), and the DeBakey VAD (MicroMed Technology, Inc., Houston, TX), which is an electromagnetically driven implantable titanium axial flow blood pump designed for left ventricular support. Despite technical improvements, VADs still are associated with serious complications. We reporte a successfull case where we replaced a TCI HeartMate with a DeBakey VAD because of a serious pocket infection, deterioration and failure of the inflow valve.     

Mechanical bridge with extracorporeal membrane oxygenation and ventricular assist device to heart transplantation

The aim of this study was to evaluate the effect of double bridges with extracorporeal membrane oxygenation (ECMO) and ventricular assist devices (VADs) in clinical heart transplantation. Between May 1994 and October 2000, 134 patients underwent heart transplantation at the National Taiwan University Hospital. Ten patients received ECMO or VAD support as bridges to transplantation. The ages ranged from 3 to 63 years. The indications included cardiac arrest under cardiopulmonary resuscitation in 2 and profound cardiogenic shock refractory to conventional therapy in 8 patients. Usually ECMO was first set up as rescue therapy. If ECMO could not be weaned off after short-term (usually 1 week) support, suitable VADs (HeartMate or Thoratec VAD) were implanted for medium-term or long-term support. Five patients received ECMO support as emergency rescue for 2 to 9 days, and then moved to Thoratec VAD for 8, 49, and 55 days, respectively, or centrifugal VAD for 31 days, or HeartMate VAD for 224 days. They all survived. The survival rate of double bridges with ECMO and VAD was 100%. In postcardiotomy cardiogenic shock, circulatory collapse from acute myocardial infarction or myocarditis, ECMO is the device of choice for short-term support. If heart transplantation is indicated, VADs should replace ECMO for their superiority as a bridge to heart transplantation. Our preliminary data of double bridges with ECMO and VAD revealed good results and were reliable and effective bridges to transplantation.     

Ventricular assist devices as a bridge to cardiac transplantation: the Ottawa experience

This article reports our experience with ventricular assist devices (VADs) as a bridge to cardiac transplantation. From 1991 to 2003, a total of 42 patients received a Thoratec VAD (Thoratec Laboratories Corporation Inc., Pleasanton, CA, U.S.A.) (Group T) and 12 patients received a Novacor VAD (WorldHeart Corporation, Ottawa, Canada) (Group N). Thirty Thoratec patients were transplanted compared to six in the Novacor group. Four more Novacor patients are still supported. Of the transplanted patients, 87% survived to hospital discharge in Group T and 67% in Group N. Infections affected 29% and 50% of Group T patients during support and post-transplantation, respectively, compared to 25% and 0%, respectively, in Group N. Neurologic complications affected 33% of patients in each group during support. Reopening rates for bleeding during support were 45% and 42% in Groups T and N, respectively. There were no significant differences in outcomes between the two groups. Our study demonstrated the effectiveness of VADs in bridging mortally ill cardiac patients to successful heart transplantation.     

Ventricular assist devices as a bridge to cardiac transplantation. A prelude to destination therapy.

OBJECTIVE AND BACKGROUND: Ventricular assist devices (VADs) have been used for temporary circulatory support pending transplantation or recovery of the native heart. Outcome in 38 patients treated at the authors' institution with VADs pending transplantation was analyzed to provide information relevant to the future use of VADs as permanent implants. METHODS: Thoratec (Thoratec Laboratories, Pleasanton, CA) or HeartMate (Thermo Cardiosystems, Woburn, MA) VADs were used in all cases. Patients were considered for VAD placement if they were candidates for cardiac transplantation and fulfilled the criteria for the Food and Drug Administration investigational Device Exemption trials. The following adverse events were included in the analysis; death during VAD support, device malfunction, bleeding, neurologic events, support-related events that preclude transplantation, and device-related infections. Patient survival and complication rates were quantified using the Kaplan-Meier method, competing risk analysis, and hazard functions. RESULTS: Nineteen patients had transplantation. Three patients had VAD removal after cardiac recovery and 16 died without transplantation. The duration of VAD support ranged from 0 to 279 days. The hazard function for death during VAD support had an early phase that lasted for 2 weeks after VAD placement, and early death was related to the preimplant condition of the patient. Device-related infections were noted in 11 patients. Seven of these patients had transplantation after clearing the infection, whereas four died without transplantation. Neurologic events occurred in seven patients. There were no device malfunctions that led to patient death. CONCLUSIONS: The absence of fatal device malfunctions suggests that longer term support with current VAD designs is feasible. Appropriate patient selection, infection control, and avoidance of thromboembolic neurologic complications will be crucial to the success of permanent VAD use.     

Ventricular assist device in patients with prosthetic heart valves

Ventricular assist device (VAD) support inpatients with a prosthetic heart valve had previously been considered a relative contraindication due to an increased risk of thromboembolic complications. We report our clinical experience of VAD implantation in patients with prosthetic heart valves, including both mechanical and bioprosthetic valves. The clinical records of 133 consecutive patients who underwent VAD implantation at a single institution from January 2002 through June 2009 were retrospectively reviewed. Six of these patients had a prosthetic valve in place at the time of device implantation. Patient demographics,operative characteristics, and postoperative complications were reviewed.Of the six patients,four were male.The mean age was 57.8 years (range 35–66 years). The various prosthetic cardiac valves included a mechanical aortic valve (n = 2), a bioprosthetic aortic valve (n = 3), and a mechanical mitral valve (n = 1).The indications for VAD support included bridge to transplantation (n = 2), bridge to recovery (n = 1), and postcardiotomy ventricular failure(n = 3). Three patients underwent left ventricular assist device placement and three received a right ventricular assist device. Postoperatively, standard anticoagulation management began with a heparin infusion (if possible)followed by oral anticoagulation.The 30-day mortality was50% (3/6). The mean duration of support among survivors was 194.3 days (range 7–369 days) compared with 16.0 days(range 4–29 days) for nonsurvivors. Of the three survivors,two were successfully bridged to heart transplantation and one recovered native ventricular function.Among the three nonsurvivors,acute renal failure developed in each case, and two developed heparin-induced thrombocytopenia. This study suggests that VAD placement in patients with a prosthethic heart valve, either mechanical or bioprosthetic,appears to be a reasonable option.     

Thrombolytic Therapy with Recombinant Streptokinase for Prosthetic Valve Thrombosis

Abstract Background: Thrombosis is a serious complication of prosthetic heart valves, and management is often difficult. Thrombolytic therapy is a promising alternative to valve reoperation in the prosthetic valve thrombosis. Methods: Fifteen consecutive patients with prosthetic heart valve thrombosis (10 mitral, 3 aortic, 2 tricuspid) were treated with intravenous recombinant Streptokinase: 250,000 UI given over 30 minutes followed by an infusion an 100,000 UI per hour, always with clinical monitoring and echocardiographic examinations repeated at 24, 48, and 72 hours after starting thrombolytic therapy. Doppler echocardiography was the primary method use for diagnosis and was also used to follow the response to therapy Results: Fibrinolytic treatment was successful in 14 (93.3%) patients. Total response was achieved in 13 (86.6%)patients and partial response in 1 (6.7%) patient; one patient died of ventricular fibrillation. No major hemorrhagic events were observed, peripheral embolism occurred in two cases, and one case of minor peripheral bleeding occurred in another. Some patients experienced fever and chills. Conclusions: The present study demonstrates the feasibility, safety and efficacy of thrombolytic therapy, which may be considered as first‐line therapy for prosthetic heart valve thrombosis.     

Does the Type of Ventricular Assisted Device Influence Survival,Infection, and Rejection Rates Following Heart Transplantation?

Abstract Objective: To determine the influence of the type of left ventricular assisted device (LVAD) as predictor of survival, hospitalizations due to infection, and rejection following heart transplantation and to delineate any further predictors of such outcomes. Methods: Patients who received a left ventricular assist device (HeartMate [Thoratec Corp., Pleasanton, CA, USA] or Novacor [World Heart Corporation, Ottawa, Canada]) as a bridge to heart transplantation between October 1991 and June 2004 using the United Network for Organ Sharing (UNOS) Thoracic Registry database were evaluated. Comparison of survival curves between HeartMate and Novacor was performed using Kaplan–Meier survival method and Cox proportional hazard model adjusting for patient demographics and co‐morbidities. Infection and rejection rates between the two devices were analyzed using multivariable logistic regression model. Results: The UNOS database provided 1255 patients with HeartMate and 154 patients with Novacor between 1991 and 2004. Unadjusted one‐ and five‐year survivals for HeartMate and Novacor were 0.84 and 0.80 and 0.72 and 0.56, respectively, following heart transplantation. Adjusting for patient demographics and co‐morbidities, no statistical significant difference in one‐year survival was observed between those who received HeartMate and Novacor (HR = 1.49, p = 0.127). At five years, however, the HeartMate group had higher survival than Novacor (HR = 1.53, p = 0.043). All‐time posttransplant hospitalizations due to infection and rejection were similar between HeartMate and Novacor recipients after adjusting for patient case mix. Conclusion: Controlling for patient case mix, there was no survival difference at one year between those who received Novacor versus HeartMate LVAD. At five years, a Novacor bridge to transplant patient on average had statistically significantly lower survival than HeartMate recipients. No difference in infection and rejection were observed.     

Non-surgical bleeding in patients with ventricular assist devices could be explained by acquired von Willebrand disease.

OBJECTIVE: Outcomes after ventricular assist device (VAD) implantation have significantly improved during the last decade. However, bleeding episodes remain a serious complication of VAD support. This cannot be explained by the individual anticoagulation regimen alone in several cases, but may be symptomatic of acquired von Willebrand disease (VWD). The leading finding in acquired VWD (AVWD) is the loss of large multimers which results in diminished binding to collagen and to the platelets. We, therefore, analysed patients with two VAD types for laboratory parameters of VWD and compared them with patients after heart transplantation (HTX). MATERIALS AND METHODS: Seven patients with a HeartMate II left-ventricular assist device and five patients who received a Thoratec biventricular assist device were included in this study. Eight HTX recipients served as controls. Analysis included international normalized ratio (INR), partial thromboplastin time (PTT), platelet count, von Willebrand factor (VWF) antigen, collagen binding capacity, ristocetin cofactor activity, the ratios of the latter two to the VWF antigen and presence of large VWF multimers. RESULTS: The VAD and HTX groups did not differ with regard to age or time-point of analysis after surgery. INR and number of platelets were comparable in both groups, PTT was prolonged in VAD patients. Both VAD and HTX patients had elevated but comparable amounts of VWF antigen. However, large multimers were missing in all of 10 tested VAD patients. In contrast, five of six tested HTX recipients displayed normal multimer pattern. Indeed, collagen binding capacity and ristocetin cofactor activity (which measures binding of VWF to platelets) were lower in VAD patients compared to HTX recipients. Impaired coagulation associated with VADs was also reflected by the diminished ratios of collagen binding capacity and ristocetin cofactor activity to VWF antigen. A pathologic collagen binding ratio was found in all 10 tested VAD patients and one of the eight HTX patients, a reduced ristocetin cofactor activity ratio in 10 of 12 VAD and one of eight HTX patients. CONCLUSION: Non-surgical postoperative bleeding after VAD implantation could be explained by an AVWD. Several pharmacologic treatment options (tranexamic acid, desmopressin, VWF-factor VIII concentrate, recombinant factor VIIa) may arise from our data. Improved VAD design could prevent this problem in the future.     

Temporal Leukocyte Numbers and Granulocyte Activation in Pulsatile and Rotary Ventricular Assist Device Patients

Individual ventricular assist device (VAD) design may affect leukocytes and impact immunity. Few studies have presented leukocyte and infection profiles in VAD patients over the course of the implant period. CD11b (MAC‐1) expression on granulocytes is an indicator of activation during inflammation, mediating extravasation and the release of reactive oxygen species in tissue. No reported studies have presented MAC‐1 expression on circulating granulocytes in VAD patients. Fifty‐six patients implanted at a single center with a HeartMate II (HMII; n = 32), HeartWare (HW; n = 12), or Thoratec pneumatic VAD (PVAD; n = 12) between 1999 and 2011 were followed for 120 days of support. The leukocyte profiles and infectious events of all patients were evaluated; additionally, a subset had MAC‐1 expression on circulating granulocytes was measured (HMII n = 9; HW n = 7; PVAD n = 4). All groups exhibited a significant peak in leukocyte numbers at postoperative day (POD) 14 while simultaneously experiencing a significant decrease in hematocrit. HMII patients exhibited a 3.2‐fold increase in granulocyte MAC‐1 expression at POD 14, and the temporal trend over the implant period differed from that experienced by HW patients. Further, HW patients experienced significantly fewer infection events. Alterations in leukocyte profiles and granulocyte activation experienced by VAD patients appear to be device‐specific. Elevations in leukocyte activation may be related to an increased risk for infection, although the specific relationship between these phenomena in this patient group is not known.     

Prosthetic valve replacement in children

Between 1975 and 1998, 27 patients aged 3 months to 14 years underwent replacement of the aortic, mitral, tricuspid, and pulmonary valves. Five different types of prosthetic valves were used; three were mechanical valves and two were bioprosthetic valves. There were 3 hospital deaths. Among the 24 survivors there were 4 late deaths. Arrhythmia requiring pacemaker implantation occurred in 2 cases after AVR and TVR. Thromboembolic events occurred in 3 patients, all with mechanical valves in pulmonary position. Infective endocarditis occurred in 1 patient after PVR with a mechanical valve. No bleeding complication occurred among the patients on a regimen of Coumadin and Dipyridamole. Two patients, both with Hancock bioprosthesis, required a second valve replacement on account of severely calcified changes. Mechanical valves in left side heart had a satisfactory long-term performance. One patient who had undergone MVR for congenital parachute mitral valve received reoperation for growth. A larger sized prosthetic valve should be used at the first replacement, and special procedures including supra-annular positioning or annular augmentation are recommended for MVR or AVR respectively.     

Increased Incidence of Gastrointestinal Bleeding Following Implantation of the HeartMate II LVAD

Abstract Background: The HeartMate II (HMII) Left Ventricular Assist System (Thoratec Corporation, Pleasanton, CA, USA), an axial continuous‐flow left ventricular assist device (LVAD), has been approved for use in bridge‐to‐transplant patients and is under investigation for destination therapy. To avoid device‐related thromboembolic complications, antiplatelet, and anticoagulation therapy are routinely administered. A worrisome frequency of gastrointestinal (GI) bleeding events has been observed. Methods: A retrospective review of all 33 patients undergoing long‐term LVAD implantation between June 1, 2006 and July 31, 2008 at our institution for any indication was conducted. Anticoagulation consisted of heparin (intravenous or subcutaneous) followed by transition to Coumadin therapy to a target INR of two to three. Antiplatelet therapy consisted of low‐dose aspirin and dipyridamole. Results: Twenty patients received the HMII and 13 patients received other devices. Eight (40%) HMII recipients suffered at least one episode of GI bleeding while no GI bleeding occurred in recipients of other devices (p = 0.012). Of 17 total bleeding episodes, no definitive source could be identified in 11 instances (65%). Conclusions: Although definitive source identification remains elusive, we believe that the majority of bleeding arises in the small bowel, possibly due to angiodysplasias, similar to the pathophysiology encountered in patients with aortic stenosis and GI bleeding. As we move toward wider use of the HMII and other axial continuous‐flow devices in both bridge‐to‐transplant patients and for destination therapy, more studies will be necessary to understand the mechanisms of this obscure GI bleeding and develop treatment strategies to minimize its development. (J Card Surg 2010;25:352‐356)     

Extracoporeal Membrane Oxygenation Hybrid With Thoratec Ventricular-Assist Devices as Double Bridge to Heart Transplantation

Ventricular-assist devices (VADs) have benefitted patients with end-stage heart failure as a bridge to heart transplantation (HTx). Herein, we describe our experience with HTx in the presence of extracorporeal membrane oxygenation (ECMO) together with the Thoratec VAD (Thoratec Corp, Pleasanton, California). From May 1996 to June 2009, mechanical circulatory support with the Thoratec VAD was provided in 20 patients. Before implantation of the VAD, circulation in 17 patients was maintained using ECMO. Although 350 patients underwent HTx during that period, only 13 patients (65%) received suitable donor organs for orthotopic HTx. The 20 patients ranged in age from 10 to 80 years; 3 were female, and 17 were male; and 17 (85%) required ECMO before VAD implantation. In 11 of 17 patients (65%), the VAD was implanted as a double bridge to HTx. The demand for mechanical circulatory support in patients with acute hemodynamic collapse has led to major improvements in clinically available systems such as ECMO as a double bridge to VAD implantation. We use ECMO as a rescue procedure in patients with acute hemodynamic deterioration. However, during ECMO support, left ventricular afterload increases. If prolonged support is necessary, a VAD may be required. We observed that 65% of patients who received support from an ECMO hybridized with the Thoratec VAD could wait for a suitable donor for HTx. We recommend use of ECMO for short-term support (<1 week) and the Thoratec VAD for medium- or long-term support as a bridge to HTx.     

The thoratec ventricular assist device: a paracorporeal pump for treating acute and chronic heart failure

The Thoratec Ventricular Assist Device (VAD) System (Thoratec Laboratories, Pleasanton, CA) is a paracorporeal pump that can provide univentricular or biventricular assistance for patients with heart failure. The system consists of a prosthetic ventricle that has a blood-pumping chamber of Thoralon (Thoratec Laboratories) polyurethane, cannulas for univentricular or biventricular support, and either a hospital-based pneumatic drive console or a portable battery-powered drive unit. For biventricular assistance, 2 pumps are used. The Thoratec voluntary registry indicates that, as of May 2000, this system had been implanted in 1,376 patients, mainly for bridging to transplantation (828 patients) or postcardiotomy support (195 patients); the remaining 353 patients received a hybrid configuration of the device or had incomplete information, so they are not included in this analysis. In the 828 bridge-to-transplant patients, the Thoratec system provided biventricular assistance in 472 cases, left ventricular assistance in 326 cases, and right ventricular assistance in 30 cases for up to 515 days. During the support period, the cardiac index increased significantly from 1.4 +/- 0.8 L/min/m2 to 3.0 +/- 0.5 L/min/m2 (with biventricular assistance and left ventricular cannulation). Sixty percent of the 828 patients underwent transplantation, and the posttransplant survival rate was 86%. In the 195 patients who needed postcardiotomy support, VADs were used for up to 80 days for cardiac recovery. Thirty-eight percent of the patients were weaned from the VAD, and 59% of the weaned group were discharged from the hospital. In addition, 49 postcardiotomy patients were considered for transplantation; of these, 32 received a transplant and 23 were discharged. Patient mobility is being improved by the use of a portable driver. The Thoratec VAD is suitable for a wide range of applications, and efforts are underway to facilitate patient mobility and allow hospital discharge. An intracorporeal version of the VAD, which is currently under development, will help achieve these goals.     

Platelet survival in patients with homograft and prosthetic heart valves: Correlation with incidence of thromboembolism

Manohitharajah, S. M., Rahman, A. N., Donnelly, R. J., Deverall, P. B., and Watson, D. A. (1974).Thorax, 29, 639-642. Platelet survival in patients with homograft and prosthetic heart valves. Investigations in the past have demonstrated shortened platelet survival time in patients with prosthetic heart valves. This suggested that platelets contribute to thromboembolism in this group. Homograft valves and the newer models of the Starr-Edwards prosthesis have proved less thrombogenic than those previously employed, but platelet survival studies in patients with these valves are lacking. In this study platelet function, survival, and its relation to haemolysis were determined in 28 patients following mitral valve replacement and in two patients following mitral valvotomy: 14 patients had a frame-mounted homograft aortic valve; 13 patients had a Starr-Edwards prosthesis model 6310 or 6320, and one had a Starr-Edwards prosthesis model 6000. Normal platelet function and survival was found in both the homograft and the Starr valve groups. The patient with the earlier model of the Starr valve (model 6000) had a shortened platelet survival time. The two patients following mitral valvotomy had normal platelet survival. The fact that platelet abnormalities were not demonstrable in our patients with homograft valves and newer Starr-Edwards prostheses may explain the low incidence of thromboembolism in this group. Platelet survival studies are a useful parameter to determine the potential thrombogenic nature of prosthetic valves. Platelet survival time was not influenced by the presence or severity of haemolysis.     

Treatment of end-stage heart disease with outpatient ventricular assist devices

BACKGROUND: Initiating outpatient therapy with ventricular assist devices (VAD) was important in the progress of mechanical circulatory support. This article reviews our experience with VAD therapy from the start of our outpatient program until the present. METHODS: Medical records of patients who received a Thoratec para-corporeal VAD, HeartMate vented electrical VAD, or HeartMate pneumatic VAD between 12/1/97 and 9/1/01 were reviewed. Variables included age, type of devices, total duration of VAD support, discharge status, duration of outpatient support, outcome (transplanted, died on support, ongoing), in-hospital length of stay after transplantation, and complications during VAD support. RESULTS: There were 53 device implants in 46 patients. The cumulative patient-days of VAD support was 7,468 (mean duration of support, 138 +/- 195 days; median, 95 days; range, 2 to 948 days). Twenty of the 46 patients were discharged with a VAD. The cumulative outpatient days was 3,600 (mean outpatient duration, 157 +/- 164 days; median, 83 days; maximum, 560 days). Of the 20 outpatients, 11 received cardiac transplantation, 5 died, and 4 are ongoing as of 9/1/01. Major complications that occurred in the outpatient setting included 5 deaths after hospital readmission (1 sepsis, 1 conduit tear, 3 neurologic events); 4 device infections (3 sepsis, 1 pouch infection); and 3 device malfunctions that required reoperation for pump replacement (1 HeartMate pneumatic and 2 HeartMate vented electrical). No deaths occurred in an outpatient setting. CONCLUSIONS: Ventricular assist devices effectively support outpatients for months to years. The anticipated time for postoperative recovery and VAD training before discharge is approximately 14 to 21 days, although shorter times may be possible in the future. Establishing a successful outpatient VAD program is a crucial step toward VAD as definitive therapy for end-stage heart disease.     

Comparison of outcomes after mitral valve replacement with a mechanical versus a bioprosthetic valve in patients between forty and sixty years of age

Background  The American College of Cardiology/American Heart Association (ACC/AHA), guidelines for choice of prosthetic valve based on patients’ age are difficult to apply to the developing world because of a lower life expectancy and difficulty in maintaining correct levels of anticoagulation for a variety of reasons. While there is general agreement on the choice of prosthetic valves for patients below 40 years of age (mechanical) and above 60 years of age (biologic), the 40 to 60 age group remains a grey zone. The goal of our study was to compare outcomes after mitral valve replacement with a mechanical versus a bioprosthetic valve in patients between forty and sixty years of age. Methods  From Jan 2003 to July 2008, 250 patients between the ages of 40 and 60, undergoing mitral valve replacement at our institution were randomized to receive either a mechanical or a bioprosthetic valve. Outcomes in the form of incidence of valve thrombosis and thromboembolism, bleeding complications, incidence of prosthetic valve endocarditis and survival were compared in the two groups. Results  Out of 250 patients, 135 patients received mechanical valve and 115 patients were implanted with a bioprosthetic valve. Patients were followed up for a mean period of 3 years (range 6 months to 4.8 years). The incidence of valve thrombosis was higher in mechanical valve as compared to bioprosthetic valve (6% vs. 0.9%, p= 0.04). Similarly there was a higher incidence of thromboembolism in mechanical valves as compared to bioprosthetic valves (4.5% vs. 0%, p=0.03). Bleeding complications occurred more frequently in mechanical than bioprosthetic valve (6% vs. 0.9%, p=0.04). There was no significant difference in the incidence of prosthetic valve endocarditis (2.2% vs. 2.7%, p >0.05) or survival at three years (96.2% vs. 97.2%, p > 0.05) in the two groups. Conclusions  Patients in the age group of 40 to 60 years undergoing mitral valve replacement with a mechanical valve have a higher incidence of thrombotic and bleeding complications as compared to bioprosthetic valve, even though short term survival is similar. This favours implantation of a bioprosthetic valve in this age group.     

Time-related risk of the St. Jude Silzone heart valve.

OBJECTIVE: The St. Jude Medical Silzone heart valve had a silver-impregnated sewing ring designed to reduce the incidence of prosthetic valve endocarditis. Recruitment to the randomized AVERT study comparing Silzone valves with non-Silzone Control valves was stopped because of an increased risk of reoperation for paravalvular leak, but patient follow-up continues. Determining the time-related risk profile of the Silzone valve is important for helping physicians manage the approximately 28,000 patients currently alive with a Silzone valve. METHODS: Between 1998 and 2000, 403 Silzone and 404 Control patients were enrolled in AVERT. As of July 2005, there were 1819 Silzone and 1842 Control patient-years of follow-up (mean 4.5, median 5.1 years). Analysis emphasized the use and interpretation of hazard functions, since they are more meaningful than event-free percentages to currently surviving patients. To this end, instead of Cox regression, which estimates the hazard ratio, assuming it is constant over time, we employed primarily Aalen additive regression, which measures the hazard difference, and produces a plot of it over time. We assessed the risks of major paravalvular leak, endocarditis, bleeding and thrombo-embolism. RESULTS: The Silzone valve had a higher initial risk of major paravalvular leak than Control in the mitral (p=0.02) position, but not in the aortic (p=0.42) position. Analysis of this risk using additive regression, with all valve positions combined, showed that the initial risk due to Silzone lost statistical significance by 2 years and disappeared by 4 years after implant. In the mitral position, the Silzone valve had a higher initial risk of thrombo-embolism plus bleeding than Control; this risk also lost statistical significance by 2 years and subsided to zero by 4 years. The risks for death and endocarditis were similar for Slizone and Control valves. CONCLUSIONS: The additional risks of the Silzone valve, compared to Control, diminish over time and disappear by 4 years after implant. The minimum time after implant of the patients currently alive with Silzone is now well beyond 5 years; thus, these current patients now have a risk profile similar to that of patients with a standard St. Jude valve.