Detection of myocardial ischemia due to clinically asymptomatic coronary artery stenosis at rest using supervised artificial intelligence-enabled vectorcardiography - A five-fold cross validation of accuracy.

BACKGROUND: Coronary artery disease (CAD) is a leading cause of death and disability. Conventional non-invasive diagnostic modalities for the detection of stable CAD at rest are subject to significant limitations: low sensitivity, and personal expertise. We aimed to develop a reliable and time-cost efficient screening tool for the detection of coronary ischemia using machine learning. METHODS: We developed a supervised artificial intelligence algorithm combined with a five lead vectorcardiography (VCG) approach (i.e. Cardisiography, CSG) for the diagnosis of CAD. Using vectorcardiography, the excitation process of the heart can be described as a three-dimensional signal. A diagnosis can be received, by first, calculating specific physical parameters from the signal, and subsequently, analyzing them with a machine learning algorithm containing neuronal networks. In this multi-center analysis, the primary evaluated outcome was the accuracy of the CSG Diagnosis System, validated by a five-fold nested cross-validation in comparison to angiographic findings as the gold standard. Individuals with 1, 2, or 3- vessel disease were defined as being affected. RESULTS: Of the 595 patients, 62·0% (n = 369) had 1, 2 or 3- vessel disease identified by coronary angiography. CSG identified a CAD at rest with a sensitivity of 90·2 ± 4·2% for female patients (male: 97·2 ± 3·1%), specificity of 74·4 ± 9·8% (male: 76·1 ± 8·5%), and overall accuracy of 82·5 ± 6·4% (male: 90·7 ± 3·3%). CONCLUSION: These findings demonstrate that supervised artificial intelligence-enabled vectorcardiography can overcome limitations of conventional non-invasive diagnostic modalities for the detection of coronary ischemia at rest and is capable as a highly valid screening tool.

The Effect of LVAD Pressure Sensitivity on the Assisted Circulation Under Consideration of a Mitral Insufficiency: An In Vitro Study.

Current left ventricular assist devices (LVADs) differ with respect to their pump characteristics as described by the pump characteristic curve (also called HQ-curve). Pressure sensitive LVADs depict a flat characteristic curve while most available LVADs have a steep, less pressure sensitive characteristic curve. This in vitro study investigated the effect of LVAD pressure sensitivity with a focus on the afterload of the right ventricle (RV) which is one out of many factors influencing right heart failure (RHF). To this end, two laboratory pumps differing in pressure sensitivity were tested as LVAD in an established, active mock circulation loop (MCL). The MCL represented patients with left heart failure and mitral insufficiency as another contributing factor to RV afterload. The results show that the pressure-volume loop (PV-loop) of the left ventricle (LV) undergoes a leftward and thus somewhat of a downward-shift for highly pressure sensitive support. Consequently, the LV is unloaded to a higher degree at comparable arterial blood pressure and identical cardiac output, pulmonary and systemic vascular resistance and ventricular contractility. This causes a concomitant decrease of RV afterload. This effect seems to be due to increased unloading during systole. In case of a severe concomitant mitral insufficiency and looking at left atrial pressure, the difference is 18.5%. Without mitral insufficiency, the difference is reduced to 10.2%.

Liver failure in total artificial heart therapy.

BACKGROUND: Congestive hepatopathy (CH) and acute liver failure (ALF) are common among biventricular heart failure patients. We sought to evaluate the impact of total artificial heart (TAH) therapy on hepatic function and associated clinical outcomes. METHODS: A total of 31 patients received a Syncardia Total Artificial Heart. Preoperatively 17 patients exhibited normal liver function or mild hepatic derangements that were clinically insignificant and did not qualify as acute or chronic liver failure, 5 patients exhibited ALF and 9 various hepatic derangements owing to CH. Liver associated mortality and postoperative course of liver values were prospectively documented and retrospectively analyzed. RESULTS: Liver associated mortality in normal liver function, ALF and CH cases was 0%, 20% (P=0.03) and 44.4% (P=0.0008) respectively. 1/17 (5.8%) patients with a normal liver function developed an ALF, 4/5 (80%) patients with an ALF experienced a markedly improvement of hepatic function and 6/9 (66.6%) patients with CH a significant deterioration. CONCLUSIONS: TAH therapy results in recovery of hepatic function in ALF cases. Patients with CH prior to surgery form a high risk group with increased liver associated mortality.

Applicability of cardiogoniometry as a non-invasive screening tool for the detection of graft vasculopathy in heart transplant recipients.

Currently available diagnostic modalities for the detection of graft vasculopathy following orthotopic heart transplantation are subject to various restrictions. We hypothesized that cardiogoniometry, a novel non-invasive diagnostic tool for the detection of atherosclerotic coronary vessel disease, is applicable in the graft vasculopathy setting. Cardiogoniometric results were obtained during routine follow-up in 49 consecutive, unselected heart transplant recipients and then retrospectively correlated blindly by an independent reader to recent angiographic findings. Sensitivity of cardiogoniometry was 100%, specificity 62.3%, positive predictive value 68.75%, negative predictive value 100%, negative likelihood ratio 0 and positive likelihood ratio 2.888. Cardiogoniometry is potentially applicable as an easy-to-perform, non-invasive screening tool predominantly for the exclusion but also for the detection of graft vasculopathy in heart transplant recipients.

Implantation technique of the 50-cm3 SynCardia Total Artificial Heart: does size make a difference?

Despite downsizing, implantation technique of the 50-cm(3) SynCardia Total Artificial Heart and settings of the Companion driver remain unchanged. Owing to the absence of de-airing nipples, de-airing procedure is even more crucial and has to be performed carefully.

Expanding Applicability of Total Artificial Heart Therapy: The 50-cc SynCardia Total Artificial Heart.

The 50-cc SynCardia total artificial heart is designed to facilitate orthotopic replacement of the native ventricles in patients with a body surface area below 1.7 m(2) in need of long-term circulatory support as a result of end-stage biventricular heart failure. We describe the implementation of this technology in a female patient with irreversible cardiogenic shock on the grounds of acute myocardial infarction and chronic ischemic cardiomyopathy.

Percutaneous dilatational tracheostomy following total artificial heart implantation.

Coagulation disorders and an immune-altered state are common among total artificial heart patients. In this context, we sought to evaluate the safety of percutaneous dilatational tracheostomy in cases of prolonged need for mechanical ventilatory support. We retrospectively analysed the charts of 11 total artificial heart patients who received percutaneous dilatational tracheostomy. We focused on early and late complications. We observed no major complications and no procedure-related deaths. Early minor complications included venous oozing (45.4%) and one case of local infection. Late complications, including subglottic stenosis, stomal infection or infections of the lower respiratory tract, were not observed. In conclusion, percutaneous dilatational tracheostomy in total artificial heart patients is safe. Considering the well-known benefits of early tracheotomy over prolonged translaryngeal intubation, we advocate early timing of therapy in cases of prolonged mechanical ventilation.

Diagnosis of obstructive coronary artery disease by cardiogoniometry: a field test in a real-life setting.

Cardiogoniometry is an electrocardiographic and vectorcardiographic method utilizing computer-assisted analysis of cardiac potentials focusing on T-wave abnormalities resulting from myocardial malperfusion. We describe a case of diagnosis of obstructive coronary artery disease with this method and discuss the possible implications for the clinical setting.

System overview of the fully implantable destination therapy--ReinHeart-total artificial heart.

OBJECTIVES: Owing to the lack of suitable allografts, the demand for long-term mechanical circulatory support in patients with biventricular end-stage heart failure is rising. Currently available Total Artificial Heart (TAH) systems consist of pump units with only limited durability, percutaneous tubes and bulky external equipment that limit the quality of life. Therefore we are focusing on the development of a fully implantable, highly durable destination therapy total artificial heart. METHODS: The ReinHeart-TAH system consists of a passively filling pump unit driven by a low-wear linear drive between two artificial ventricles, an implantable control unit and a compliance chamber. The TAH is powered by a transcutaneous energy transmission system. The flow distribution inside the ventricles was analysed by fluid structure interaction simulation and particle image velocimetry measurements. Along with durability tests, the hydrodynamic performance and flow balance capability were evaluated in a mock circulation loop. Animal trials are ongoing. RESULTS: Based on fluid structure interaction simulation and particle image velocimetry, blood stagnation areas have been significantly reduced. In the mock circulation loop the ReinHeart-TAH generated a cardiac output of 5 l/min at an operating frequency of 120 bpm and an aortic pressure of 120/80 mmHg. The highly effective preload sensitivity of the passively filling ventricles allowed the sensorless integration of the Frank Starling mechanism. The ReinHeart-TAH effectively replaced the native heart's function in animals for up to 2 days. CONCLUSIONS: In vitro and in vivo testing showed a safe and effective function of the ReinHeart-TAH system. This has the potential to become an alternative to transplantation. However, before a first-in-man implant, chronic animal trials still have to be completed.

Nocardiosis in Heart Transplant Recipients.

Nocardia has emerged as an important opportunistic pathogen, especially in organ transplant recipients. Heart transplant (HT) recipients initially had an especially high rate of Nocardia infection, but this could be reduced by the routine use of cyclosporine. Our objective was to clarify the prevalence and presentation of Nocardiosis in HT recipients in a retrospective cross-sectional analysis.

Normothermic ex vivo allograft blood perfusion in clinical heart transplantation.

BACKGROUND: Cold ischemia associated with cold static storage is an independent risk factor for primary allograft failure and survival of patients after orthotopic heart transplantation. The effects of normothermic ex vivo allograft blood perfusion on outcomes after orthotopic heart transplantation compared to cold static storage have been studied. METHODS: In this prospective, nonrandomized, single-institutional clinical study, normothermic ex vivo allograft blood perfusion has been performed using an organ care system (OCS) (TransMedics, Andover, MA, USA). Included were consecutive adult transplantation patients who received an orthotopic heart transplantation (oHTx) without a history of any organ transplantation, in the absence of a congenital heart disorder as an underlying disease and not being in need of a combined heart-lung transplantation. Furthermore, patients with fixed pulmonary hypertension, ventilator dependency, chronic renal failure, or panel reactive antibodies >20% and positive T-cell cross-matching were excluded. Inclusion criteria for donor hearts was age of <55 years, systolic blood pressure >85 mmHg at the time of final heart assessment under moderate inotropic support, heart rate of <120 bpm at the time of explantation, and left ventricular ejection fraction >40% assessed by an transcutaneous echo/Doppler study with the absence of gross wall motion abnormalities, absence of left ventricular hypertrophy, and absence of valve abnormalities. Donor hearts which were conventionally cold stored with histidine-tryptophan-ketoglutarate solution (Custodiol; Koehler Chemie, Ansbach, Germany) constituted the control group. The primary end point was the recipients' survival at 30 days and 1 and 2 years after their heart transplantation. Secondary end points were primary and chronic allograft failure, noncardiac complications, and length of hospital stay. RESULTS: Over a 2-year period (January 2006 to July 2008), 159 adult cardiac allografts were transplanted. Twenty-nine were assigned for normothermic ex vivo allograft blood perfusion and 130 for cold static storage with HTK solution. Cumulative survival rates at 30 days and 1 and 2 years were 96%, 89%, and 89%, respectively, whereas in the cold static storage group survival after oHTx was 95%, 81%, and 79%. Primary graft failure was less frequent in the recipients of an oHTx who received a donor heart which had been preserved with normothermic ex vivo allograft blood perfusion using an OCS (6.89% versus 15.3%; P = .20). Episodes of severe acute rejection (23% versus 17.2%; P = .73), as well as, cases of acute renal failure requiring haemodialysis (25.3% versus 10%; P = .05) were more frequent diagnosed among recipients of a donor heart which had been preserved using the cold static storage. The length of hospital stay did not differ (26 days versus 28 days; P = .80) in both groups. CONCLUSIONS: Normothermic ex vivo allograft blood perfusion in adult clinical orthotopic heart transplantation contributes to better outcomes after transplantation in regard to recipient survival, incidence of primary graft dysfunction, and incidence of acute rejection.

A first step beyond traditional boundaries: destination therapy with the SynCardia total artificial heart.

The SynCardia total artificial heart is currently used as a bridge to transplantation therapy in cases of irreversible, acute or chronic, biventricular heart failure. We describe the implementation of this technology in the context of destination therapy in a patient with an end-stage heart failure on grounds of primary amyloidosis.