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Total artificial heart

End-stage heart failure represents a highly morbid condition for the patient with limited treatment options. From a surgical perspective, the treatment options for effective long-term survival are usually limited to heart transplantation, heart-lung transplantation or implantation of a destination mechanical circulatory support device. Assuming an advanced heart-failure patient is indeed deemed a candidate for transplantation, the patient is subject to shortages in donor organ availability and thus possible further decompensation and potential death while awaiting transplantation. Various extracorporeal and implantable ventricular-assist devices (VADs) may be able to provide temporary or long-term circulatory support for many end-stage heart-failure patients but mechanical circulatory support options for patients requiring long-term biventricular support remain limited. Implantation of a total artificial heart (TAH) currently represents one, if not the best, long-term surgical treatment option for patients requiring biventricular mechanical circulatory support as a bridge to transplant. The clinical applicability of available versions of positive displacement pumps is limited by their size and complications. Application of continuous-flow technology can help in solving some of these issues and is currently being applied in the research towards a new generation of smaller and more effective TAHs. In this review, we discuss the history of the TAH, its development and clinical application, implications for anaesthetic management, published outcomes and the future outlook for TAHs.

Using Near-Infrared Spectroscopy to Monitor Lower Extremities in Patients on Venoarterial Extracorporeal Membrane Oxygenation

Patients on peripheral extracorporeal membrane oxygenation (ECMO) are at risk for lower extremity ischemia. Effective monitoring is needed to identify complications quickly and allow timely correction. Near-infrared spectroscopy has been used extensively in cerebral monitoring during cardiac surgery. We present its use in monitoring lower extremity perfusion in patients on ECMO. Five patients on ECMO had near-infrared spectroscopy monitors placed on the calf of both lower extremities. Continuous real-time tissue oxygen saturation data (stO2) was displayed and recorded. Two patients had lower extremity complications in the leg with the arterial cannula. The patients with complications had lower stO2 in the cannulated leg at the time of ECMO insertion, larger differences in stO2 between the legs at the time of insertion, lower nadir stO2s, and larger peak differences in stO2 between the legs than patients without limb complications. The use of near-infrared spectroscopy for continuous monitoring of tissue oxygenation in the lower extremities in patients on ECMO may allow early identification of patients with lower extremity complications.

Early left and right ventricular response to aortic valve replacement

BACKGROUND: The immediate effect of aortic valve replacement (AVR) for aortic stenosis on perioperative myocardial function is unclear. Left ventricular (LV) function may be impaired by cardioplegia-induced myocardial arrest and ischemia-reperfusion injury, especially in patients with LV hypertrophy. Alternatively, LV function may improve when afterload is reduced after AVR. The right ventricle (RV), however, experiences cardioplegic arrest without benefiting from improved loading conditions. Which of these effects on myocardial function dominate in patients undergoing AVR for aortic stenosis has not been thoroughly explored. Our primary objective is thus to characterize the effect of intraoperative events on LV function during AVR using echocardiographic measures of myocardial deformation. Second, we evaluated RV function. METHODS: In this supplementary analysis of 100 patients enrolled in a clinical trial (NCT01187329), 97 patients underwent AVR for aortic stenosis. Of these patients, 95 had a standardized intraoperative transesophageal echocardiographic examination of systolic and diastolic function performed before surgical incision and repeated after chest closure. Echocardiographic images were analyzed off-line for global longitudinal myocardial strain and strain rate using 2D speckle-tracking echocardiography. Myocardial deformation assessed at the beginning of surgery was compared with the end of surgery using paired t tests corrected for multiple comparisons. RESULTS: LV volumes and arterial blood pressure decreased, and heart rate increased at the end of surgery. Echocardiographic images were acceptable for analysis in 72 patients for LV strain, 67 for LV strain rate, and 54 for RV strain and strain rate. In 72 patients with LV strain images, 9 patients required epinephrine, 22 required norepinephrine, and 2 required both at the end of surgery. LV strain did not change at the end of surgery compared with the beginning of surgery (difference: 0.7 [97.6% confidence interval, −0.2 to 1.5]%; P = 0.07), whereas LV systolic strain rate improved (became more negative) (−0.3 [−0.4 to −0.2] s−1; P < 0.001). In contrast, RV systolic strain worsened (became less negative) at the end of surgery (difference: 4.6 [3.1 to 6.0]%; P < 0.001) although RV systolic strain rate was unchanged (0.0 [97.6% confidence interval, −0.1 to 0.1]; P = 0.83). CONCLUSIONS: LV function improved after replacement of a stenotic aortic valve demonstrated by improved longitudinal strain rate. In contrast, RV function, assessed by longitudinal strain, was reduced.

Median Sternotomy or Right Thoracotomy Techniques for Total Artificial Heart Implantation in Calves

The choice of optimal operative access technique for mechanical circulatory support device implantation ensures successful postoperative outcomes. In this study, we retrospectively evaluated the median sternotomy and lateral thoracotomy incisions for placement of the Cleveland Clinic continuous-flow total artificial heart (CFTAH) in a bovine model. The CFTAH was implanted in 17 calves (Jersey calves; weight range, 77.0-93.9 kg) through a median sternotomy (n = 9) or right thoracotomy (n = 8) for elective chronic implantation periods of 14, 30, or 90 days. Similar preoperative preparation, surgical techniques, and postoperative care were employed. Implantation of the CFTAH was successfully performed in all cases. Both methods provided excellent surgical field visualization. After device connection, however, the median sternotomy approach provided better visualization of the anastomoses and surgical lines for hemostasis confirmation and repair due to easier device displacement, which is severely limited following right thoracotomy. All four animals sacrificed after completion of the planned durations (up to 90 days) were operated through full median sternotomy. Our data demonstrate that both approaches provide excellent initial field visualization. Full median sternotomy provides larger viewing angles at the anastomotic suture line after device connection to inflow and outflow ports.

Hyperinsulinemic Normoglycemia Does Not Meaningfully Improve Myocardial Performance during Cardiac Surgery: A Randomized Trial.

Background:Glucose–insulin–potassium (GIK) administration during cardiac surgery inconsistently improves myocardial function, perhaps because hyperglycemia negates the beneficial effects of GIK. The hyperinsulinemic normoglycemic clamp (HNC) technique may better enhance the myocardial benefits of GIK. The authors extended previous GIK investigations by (1) targeting normoglycemia while administering a GIK infusion (HNC); (2) using improved echocardiographic measures of myocardial deformation, specifically myocardial longitudinal strain and strain rate; and (3) assessing the activation of glucose metabolic pathways. Methods:A total of 100 patients having aortic valve replacement for aortic stenosis were randomly assigned to HNC (high-dose insulin with concomitant glucose infusion titrated to normoglycemia) versus standard therapy (insulin treatment if glucose >150 mg/dl). The primary outcomes were left ventricular longitudinal strain and strain rate, assessed using speckle-tracking echocardiography. Right atrial tissue was analyzed for activation of glycolysis/pyruvate oxidation and alternative metabolic pathways. Results:Time-weighted mean glucose concentrations were lower with HNC (127 ± 19 mg/dl) than standard care (177 ± 41 mg/dl; P < 0.001). Echocardiographic data were adequate in 72 patients for strain analysis and 67 patients for strain rate analysis. HNC did not improve myocardial strain, with an HNC minus standard therapy difference of −1.2% (97.5% CI, −2.9 to 0.5%; P = 0.11). Strain rate was significantly better, but by a clinically unimportant amount: −0.16 s−1 (−0.30 to −0.03 s−1; P = 0.007). There was no evidence of increased glycolytic, pyruvate oxidation, or hexosamine biosynthetic pathway activation in right atrial samples (HNC, n = 20; standard therapy, 22). Conclusion:Administration of glucose and insulin while targeting normoglycemia during aortic valve replacement did not meaningfully improve myocardial function.

Anatomy of the bovine ascending aorta and brachiocephalic artery found unfavorable for total artificial heart implant

The biocompatibility assessment of the Cleveland Clinic continuous-flow total artificial heart is an important part of the device developmental program. Surgical and postoperative management are key factors in achieving optimal outcomes. However, the presence of vascular anatomical abnormalities in experimental animal models is often unpredictable and may worsen the expected outcomes. We report a technical impediment encountered during total artificial heart implantation complicated by unfavorable bovine anatomy of the ascending aorta and brachiocephalic arterial trunk.

Acquired "Gerbode-like" defect in aortic valve endocarditis: an imposter for tricuspid regurgitation?

e v e t fi t a m w e m e i v 4 A59-YEAR-OLD woman with a bioprosthetic aortic valve was referred to the authors’ heart and vascular institute for rosthetic valve endocarditis with blood cultures positive for ethicillin-sensitive Staphylococcus aureus. The transesophaeal echocardiogram (TEE) showed mobile densities on the ortic and ventricular surfaces of the Carpentier-Edwards aortic alve leaflets. The patient was scheduled for an urgent valve eplacement with an aortic valve homograft. After an un-

Novel technique for airless connection of artificial heart to vascular conduits

Successful implantation of a total artificial heart relies on multiple standardized procedures, primarily the resection of the native heart, and exacting preparation of the atrial and vascular conduits for pump implant and activation. Achieving secure pump connections to inflow/outflow conduits is critical to a successful outcome. During the connection process, however, air may be introduced into the circulation, traveling to the brain and multiple organs. Such air emboli block blood flow to these areas and are detrimental to long-term survival. A correctly managed pump-to-conduit connection prevents air from collecting in the pump and conduits. To further optimize pump-connection techniques, we have developed a novel connecting sleeve that enables airless connection of the Cleveland Clinic continuous-flow total artificial heart (CFTAH) to the conduits. In this brief report, we describe the connecting sleeve design and our initial results from two acute in vivo implantations using a scaled-down version of the CFTAH.

Abnormalities of Mitral Subvalvular Apparatus in Hypertrophic Cardiomyopathy: Role of Intraoperative 3D Transesophageal Echocardiography.

1094 www.anesthesia-analgesia.org November 2016 • Volume 123 • Number 5 Written informed consent was obtained from the patient for publication of this report. A 59-year-old man with hypertrophic cardiomyopathy (HCM) was referred to our institution for myectomy. His symptoms included nonradiating midsternal pain and shortness of breath occurring after mild to moderate physical activity. A preoperative transthoracic echocardiogram revealed systolic anterior motion (SAM) of the anterior mitral leaflet, which increased markedly with exercise resulting in a peak systolic left ventricular outflow tract (LVOT) gradient of 129 mm Hg. A peak systolic left ventricular midcavity gradient of 73 mm Hg was also noted. The basal septum was moderately hypertrophic with a thickness of 1.5 cm. Cardiac magnetic resonance (CMR) imaging was also performed to evaluate papillary muscle (PM) morphology. Apart from a mild hypertrophy of the anterolateral PM, CMR was unremarkable. Since medical management did not improve symptoms, surgical myectomy was advised. Intraoperative transesophageal echocardiography (TEE) confirmed SAM, systolic flow acceleration in LVOT, and mitral regurgitation of 2+ severity (Figure 1). A hypertrophic anterolateral PM (Figure 2) with abnormal movement toward the interventricular septum during systole was also observed (Supplemental Digital Content 1, Video 1, http:// links.lww.com/AA/B498). Further evaluation using 3D TEE revealed a muscle bridge originating from the anterolateral PM and attaching itself to the interventricular septum (Supplemental Digital Content 2, Video 2, http://links. lww.com/AA/B499). This abnormal subvalvular anatomy resulted in abnormal displacement of anterolateral PM toward the septum during systole, causing LVOT obstruction. The details of the abnormal PM anatomy were communicated with the surgical team, aided by 3D images. Routine echocardiographic measurement of the septum was also obtained to determine the extent of myectomy. The anatomy seen on 3D echocardiography was confirmed surgically. In addition to standard septal myectomy, the vertically oriented bridging segment of the anterolateral PM was excised. After separation from cardiopulmonary bypass, TEE confirmed absence of SAM (Supplemental Digital Content 3, Video 3, http://links.lww.com/AA/B500), and showed trivial mitral regurgitation and absent LVOT gradients (Figure 3), on provocation with isoproterenol at 20 μg/min). Rest of the surgery and postoperative stay was unremarkable.

Acute Drainage of Pericardial Effusion May Precipitate Right Ventricular Failure

CONTRIBUTION OF AN INTACT PERICARDIUM toward optimal ventricular function is not well-delineated. The restraining effect of the pericardium against right ventricular dilatation in a setting of increased afterload may be protective. The authors present a case report of acute hemodynamic deterioration following pericardial effusion drainage secondary to worsening of right ventricular failure in a patient with acute-on-chronic increase in right ventricular afterload. As the protective pericardial restraint against dilatation is more conspicuous in these conditions, caution should be exercised and efforts to optimize right ventricular contractility and loading conditions should be initiated prior to drainage of a seemingly clinically significant effusion.