Successful left ventricular assist device re-implantation with omental covering for MDRP device infection

We present a case of paracorporeal left ventricular assist device (p-LVAD)-related infection, caused by multi-drug resistant Pseudomonas aeruginosae (MDRP), and successfully treated by p-LVAD re-implantation with omental covering. A 59-year-old man underwent p-LVAD implantation and coronary artery bypass grafting after percutaneous cardiopulmonary support and intra-aortic balloon pumping for cardiogenic shock due to acute myocardial infarction. Then, he was registered for heart transplantation. He suffered from blood stream infection causative organism of Pseudomonas aeruginosa, 2 months after that operation. He underwent re-median sternotomy and open drainage, 15 months after the p-LVAD implantation. However, he suffered from septic shock due to MDRP. He underwent p-LVAD re-implantation under hypothermic circulatory arrest and iodine gauze packing, followed by omental covering of the all artificial materials in his body 10 days after that operation. Soon after that, the infection was well controlled and the intravenous antibiotics could be discontinued 2 months after that operation. He successfully underwent heart transplantation, 17 months after that procedure. We concluded that p-LVAD re-implantation with omental covering is seemed to be useful in the treatment of massive device infection. This procedure might be a novel treatment for severe VAD-related infection until heart transplantation.     

Correlation between driveline features and driveline infection in left ventricular assist device selection

Although the survival rate for left ventricular assist device (LVAD) therapy has improved, device-related complications are an unpredictable threat to the patient’s quality of life. We focused on driveline infection, and aimed to determine whether specific features of drivelines affect the frequency of infection. We enrolled patients who underwent LVAD implantation and were followed-up at our institute between 2007 and 2015. We counted the occurrences of driveline infection requiring any antibiotic therapy over a 2-year study period. Furthermore, we experimentally measured and compared the outer diameters and stiffness of three devices. Of all, 72 patients received an LVAD during the enrollment period. LVADs were HeartMate II (n = 32), EVAHEART (n = 22), and DuraHeart (n = 18). The outer diameters and stiffness were measured in five of each device. HeartMate II group had the highest driveline infection-free rate among all three devices during the study period (p = 0.042). The driveline of the HeartMate II LVAD had a significantly smaller outer diameter and lower stiffness than that of the other two devices (p < 0.05 for both). In conclusion, device-specific driveline features may affect the development of driveline infection during LVAD therapy.     

Regenerating a ventricular cavity during left ventricular assist device implantation

Journal of Artificial Organs - Ten months after an ineffective percutaneous coronary stent placement, a 53-year-old patient was rehospitalized with NYHA functional class IV congestive heart...     

Thymidine auxotrophic Staphylococcus aureus small-colony variant endocarditis and left ventricular assist device infection

We describe a thymidine-dependent small-colony variant of Staphylococcus aureus associated with left ventricular assist device infection and prosthetic valve and pacemaker endocarditis.     

Readmissions after continuous flow left ventricular assist device implantation

Continuous flow left ventricular assist device (CF-LVAD) therapy has improved the survival of patients with advanced heart failure. However, the readmission rate of CF-LVAD patients is still relatively high. A total of 90 patients who received CF-LVADs between April 2011 and March 2016 at our institute and were discharged home were analyzed retrospectively. They were followed up through March 2017. Clinical data, including frequency, length and etiology of readmission, were obtained from medical records. The mean observation period after initial discharge was 713 ± 322 days. In total, 73 patients (81%) had 236 readmissions, 214 unplanned and 22 planned. The overall and unplanned readmission rates were 1.34 and 1.22 per patient-year, respectively. The rate of freedom from unplanned first readmission at 1 year after initial discharge was 39%. The median interval between the previous hospital discharge and first and second readmissions was 311 and 213 days, respectively (log-rank test, p = 0.117). The rate of readmission after more than three readmissions was significantly higher than that of first or second readmission (log-rank test, p < 0.001). The most common etiology of readmission was driveline infection (DLI) (36%), followed by stroke (9%). The median length of hospital stay due to DLI was 23 days. The patients with repeated unplanned readmissions had significantly lower EuroQol 5 dimensions questionnaire utility score than those with no or just one readmission. Readmission was common in CF-LVAD patients, and the most common etiology of readmissions was DLI. The interval to the next readmission seemed shorter for patients with repeated readmissions.     

Anticoagulation during use of a left ventricular assist device

Thirty-six mongrel dogs underwent 24hr left ventricular assist. The VAD was placed between the left atrium and the descending aorta, and the dogs were divided into four groups according to type of anticoagulation: no anticoagulation, argatroban, nafamostat mesylate, and nafamostat mesylate + prostacyclin analog. Results of this animal experiment revealed that a newly developed synthetic thrombin inhibitor argatroban can prevent activation of the intrinsic coagulation pathway. Argatroban is efficient under any blood coagulative condition, even lack of anti-thrombin III, because of its direct inhibitory effect on thrombin, making argatroban more useful than heparin as an anticoagulant for LVAD. Argatroban, as well as heparin, provides marked and significant prolongation of the prothrombin time from early assisted circulation, but produces a bleeding tendency. Nafamostat mesylate can maintain blood coagulation parameters within the acceptable range. Combined administration of nafamostat mesylate and a prostacyclin analog cause the least decrease in fibrinogen and alpha2-plasmin inhibitor among the four groups and causes no significant prolongation of prothrombin time.     

In vitro evaluation of an implantable left ventricular assist device

The development of implantable left ventricular assist devices (LVADs) has almost reached the stage of providing permanent circulatory support in patients who are unsuitable for, or denied, the transplant option. As part of our ongoing haemodynamic evaluation of the Thermo Cardiosystems Inc. (Boston, USA) Mark 14 pneumatic LVAD, pressure-volume loops have been produced from in vitro studies using a modified National Heart Lung and Blood Institute (NHLBI, USA) mock circulatory loop. These studies have demonstrated that during certain phases of the pump cycle non-physiologically high and low pressures are generated within the LVAD. Such abnormal pressures may damage either the bioprosthetic valves in the LVAD or the native heart, and may have adverse effects on cardiovascular control mechanisms.     

Recovery directed left ventricular assist device: a new concept

To promote cardiac recovery, we developed a recovery directed left ventricular assist device (RDLVAD) that consists of a valved apical conduit, an afterload controlling chamber (ACC), and a pump. We evaluated its efficacy by comparison with an ordinary LVAD. In each of six pigs with ischemia-induced heart failure, flow and pressure measurements were made while maintaining the total blood flow and arterial pressure equal in the two groups. RDLVAD was able to direct all the blood ejected from the LV into the ACC (0-15 mm Hg) but not into the aorta (73 mm Hg). In the ordinary LVAD, however, some ejection occurred into the aorta despite vigorous suction of the LV. Thus, RDLVAD increased DPTI/SPTI 2.3 times (p < 0.005) and decreased left ventricular end-diastolic pressure by 40% and maximum dP/dt by 20% (p < 0.05). Even the apical valve, at approximately half the diameter of the aortic valve, was able to allow all the blood ejected from the LV to enter the ACC. In one control group pig that achieved almost no ejection into the aorta, left ventricular relaxation and dilatation was extremely limited. RDLVAD may promote cardiac recovery by ensuring less LV work, a greater blood supply/demand ratio in the coronary circulation, and full ventricular relaxation.     

Mechanical mitral prosthesis with a short-term left ventricular assist device

Mechanical circulatory support with ventricular assist devices in patients with mechanical valvular prostheses may predispose to thromboembolic and hemodynamic complications. Conventional approaches to reduce these risks involve redo valve replacement to a bioprosthesis. Careful management of the ventricular assist device to allow flow across the prosthesis may obviate the need for redo valve replacement. Avoidance of further myocardial ischemia during redo valve replacement carries particular importance for patients in whom the aim is recovery. We report a successful outcome from retention of a mechanical mitral prosthesis during a 10-day period of mechanical circulatory support and review the pertinent literature.     

Ventricular assist device infection necessitating device exchange following extensive myocardial resection

A 14-year-old boy undergoing long-term mechanical circulatory support with a left ventricular assist device (LVAD) developed myocardial abscess resulting from cannula exit-site infection. This critically ill patient was successfully treated with LVAD replacement and omentopexy following extensive myocardial debridement. Although the use of artificial materials in the face of active infection is not ideal, other options including LVAD explantation or urgent heart transplantation are not always feasible depending on the patient’s cardiac function and the availability of a donor heart. Under such circumstances, LVAD replacement might be the only measure available that could save patients who otherwise would not survive.     

Operative modification for the prevention of device-related infection during NIPRO extracorporeal left ventricular assist device implantation

An operative modification in which the NIPRO left ventricular assist device (LVAD) cannulas are passed through the intraperitoneal cavity is performed as the first-choice standard technique in our institution. Eighteen consecutive patients who underwent NIPRO LVAD implantation as heart transplantation candidates were enrolled in this study. The cannulas were passed through the intraperitoneal cavity in 11 patients (Group IP) and the extraperitoneal space in 7 patients (Group EP). A device-related major infection was defined as bloodstream infection and/or abscess formation in the deep tissue space. Device-related major infection occurred in 6 patients in Group IP and in 6 patients in Group EP. Of these patients, 3 patients in Group IP and 5 patients in Group EP suffered from uncontrollable bloodstream infection and finally died of development into multiple organ failure and/or cerebrovascular accidents. The actuarial rates of freedom from device-related major infection at 6 months after LVAD implantation were 100 % in Group IP and 38 % in Group EP, respectively (p = 0.02). Moreover, the actuarial survival rates after the initial device-related major infection in Group IP could be significantly higher than in Group EP (83 and 67 % at 6 months, p = 0.03). We demonstrated that this operative modification can contribute to prevention of progression of superficial skin infection to critical infection and to extension of the survival duration after the initial device-related major infection.     

左室辅助循环对急性左心衰犬肾素血管紧张素系统影响

目的:研究不同辅助流率对急性左心衰时肾素血管紧张素系统(RAS)的影响.方法:对20条急性左心衰犬进行高、中、低流量的180 min左室辅助,观察其对血液动力学及RAS的影响.结果:左室辅助循环可使急性左心衰犬平均左房压、血浆肾素、血管紧张素Ⅱ迅速下降,平均主动脉压、左室搏功指数均升高.结论:不同辅助流量对急性左心衰时左心血液动力学支持均有效,但以中流量效果最佳.神经内分泌因子是评价LVAD效果敏感而有效的指标.     

Prognostic value of left ventricular apical tissue removed for HeartMate II left ventricular assist device placement

BackgroundWith the increasing use of left ventricular assist devices, the left ventricular apical core has become a more frequently encountered surgical pathology tissue. We investigated the prognostic value of this cardiac tissue in short-term patient mortality. Previous studies have shown that the degree of cardiac fibrosis correlates with improvements in ejection fraction and the likelihood of weaning from an assist device.MethodsLeft ventricular apical core tissues from 29 sequential subjects who received a HeartMate II continuous axial flow left ventricular assist device were studied retrospectively to determine whether interstitial fibrosis, replacement fibrosis (scar), the presence of mural thrombus, or other histopathologic findings were associated with hemodynamic changes or mortality in this population. Patients received left ventricular assist devices as bridges to transplantation or as destination therapy. Interstitial fibrosis was determined by observer scoring and digital scoring methods. Before and after left ventricular assist device procedure, right heart catheterizations were reviewed for clinical cardiac data.ResultsThe presence of replacement fibrosis in the apical core tissue significantly correlated with decreased improvement in pulmonary capillary wedge pressure after left ventricular assist device placement (P=.02). Ten subjects died over the course of this study. No specimen variables, including scar, interstitial fibrosis, and the presence of mural thrombosis, correlated with patient mortality.ConclusionsPathologic findings in left ventricular apical cores have little prognostic utility in guiding patient management as related to overall 1-year mortality, but may indicate patients who are more likely to positively remodel their hearts.     

一种经皮植入式左心辅助装置的泵流量测试

目的 研究设计一种能用于心血管急危重症的经皮植入式左心辅助装置（血泵）。方法 根据机翼理论,设计一种经皮植入的左心辅助装置,通过测量3种不同参数（叶片旋转角度、血泵出水口距离、血泵出水口长度）的血泵所能产生的流量,最终选择最优化的血泵设计。结果 经过简易流量测定装置测量,当血泵采取单叶设计,血泵叶片的旋转角度为720°时,或血泵出水口与叶片的距离为0 mm时,血泵出水口长度为4 mm时,血泵流量最大。结论 选择能产生最大流量的参数值,研制出一种可在体外正常运转的经皮植入式左心辅助装置,为最终研制一种可用于临床的经皮植入式左心辅助装置提供理论和数据支持。