Left Ventricular Assist Device Inflow Cannula Research Articles

Abstract 14358: A Rare Case of Refractory Ventricular Arrhythmias Caused by Subacute Aortic Root Thrombosis Following Left Ventricular Assist Device

Introduction: Aortic Root thrombus (ART) is relatively uncommon complication following left ventricular assist device (LVAD) therapy with significant morbidity and mortality. Case: A 51-year-old male with coronary artery disease with CABG (LIMA to LAD and sequential SVG) presented with acute cardiogenic shock. EKG showed right bundle branch block with diffuse T wave inversions. Coronary angiogram showed severe three vessel disease with occlusion of all vein grafts except LIMA-LAD. Patient subsequently underwent LVAD with HM3 implant placement as a destination therapy. He was started on warfarin with heparin drip as a bridge. Post op course was complicated by recurrent VF storm. Patient was started on amiodarone and lidocaine. A transthoracic echocardiogram showed LVAD inflow cannula in place and aortic valve was noted to be closed with every beat. HM3 speed was decreased to 5500 rpm. Patient continued to have recurrent episodes of VF, refractory to cardioversion and anti-arrhythmic agents. CT angiogram showed aortic root filling defect consistent with thrombosis extending from the leaflets towards the Sino tubular junction, along the left coronary cusp leaflets. Patient eventually required VT ablation for refractory ventricular arrhythmia. Patient underwent median sternotomy for surgical removal of aortic root thrombus which showed parts of the thrombus intimately connected to the aortic root wall including the left main and right coronary ostia. Post op patient was continued on systematic anticoagulation with noted clinical improvement. Conclusion: ART after LVAD placement is a rare complication and can be associated with myocardial infarction and thromboembolic events. It can compromise coronary perfusion and result in ischemic ventricular arrhythmias as seen in our case. Management includes surgical removal of the pump or orthoptic heart transplantation. VT ablation should be considered if no ischemic culprit identified

Relapsing low-flow alarms due to suboptimal alignment of the left ventricular assist device inflow cannula.

This retrospective study investigated the correlation between the angular position of the left ventricular assist device (LVAD) inflow cannula and relapsing low-flow alarms. Medical charts were reviewed of all patients with HeartMate 3 LVAD support for relapsing low-flow alarms. A standardized protocol was created to measure the angular position with a contrast-enhanced computed tomography scan. Statistics were done using a gamma frailty model with a constant rate function. For this analysis, 48 LVAD-supported patients were included. The majority of the patients were male (79%) with a median age of 57 years and a median follow-up of 30 months (interquartile range: 19-41). Low-flow alarm(s) were experienced in 30 (63%) patients. Angulation towards the septal-lateral plane showed a significant increase in low-flow alarms over time with a constant rate function of 0.031 increase in low-flow alarms per month of follow-up per increasing degree of angulation (P = 0.048). When dividing this group using an optimal cut-off point, a significant increase in low-flow alarms was observed when the septal-lateral angulation was 28° or more (P = 0.001). Anterior-posterior and maximal inflow cannula angulation did not show a significant difference. This study showed an increasing number of low-flow alarms when the degrees of LVAD inflow cannula expand towards the septal-lateral plane. This emphasizes the importance of the LVAD inflow cannula angular position to prevent relapsing low-flow alarms with the risk of diminished quality of life and morbidity.

Minimally Invasive Left Ventricular Assist Device Insertion with Concomitant Aortic Valve Replacement Despite Prior Sternotomy

<h3>Introduction</h3> Minimally-invasive approaches to left ventricular assist device (LVAD) insertion have been described. However, reoperative sternotomy and/or need for concomitant procedures have been regarded as relative contraindications to a minimally-invasive approach. <h3>Case Report</h3> A 61 year-old female with ischemic cardiomyopathy and prior coronary bypass grafting via median sternotomy was deemed an appropriate candidate for LVAD insertion. While preoperative echocardiography demonstrated mild aortic insufficiency, intra-operative imaging revealed moderate aortic insufficiency. Intra-operatively, the aorta was accessed via a partial upper sternotomy to the 4^th intercostal space. The ventricular apex was accessed through a left anterolateral thoracotomy. Cardiopulmonary bypass was established via an aortic cannula inserted via the ascending aorta and a multi-stage venous cannula inserted into the right femoral vein. Cardioplegia was administered first via an antegrade aortic root catheter, and then later via retrograde catheter and direct coronary ostial cannulation during the valve replacement. The aortic valve was replaced with a 21-mm bioprosthetic valve via the partial sternotomy (Fig A). After aortotomy closure, the cross-clamp was removed and the heart re-perfused. An apical ventriculotomy was then created and the LVAD inflow cannula was inserted into the left ventricle and secured to the sewing ring (Fig B). The outflow graft was tunneled to the upper sternotomy and anastomosed to the aorta using a side-biting clamp. The postoperative course was notable for pneumonia leading to temporary re-intubation. She otherwise did well, and was discharged home on post-LVAD day 23. <h3>Summary</h3> Both a history of a prior sternotomy and the need for concomitant procedures present challenges to use of minimally-invasive approaches for LVAD insertion. Here, we demonstrate that concomitant AVR can be safely performed along with LVAD insertion in a reoperative setting.

Numerical study of the effect of LVAD inflow cannula positioning on thrombosis risk

Left ventricular assist devices (LVADs) have been increasingly used as a therapy for patients with end-stage heart failure. However, a growing number of clinical observations have shown that LVADs are associated with thromboembolic events, which are potentially related to the changes in intraventricular flow. Particularly, the flow fields around the inflow cannula (IC) of the LVAD. In this study, a fluid structure interaction (FSI) simulation was conducted to evaluate the hemodynamics of a patient specific left ventricle (LV) with varying LVAD IC orientations. The LV model was obtained from computed tomography scans and modeled to have contraction and relaxation during cardiac cycles following available experimental data of LV volume changes. The LV of the patient was assumed to have an end systolic volume of 223.7 mL and a stroke volume of 46.4 mL. Four different IC positions were considered: towards the (1) septum; (2) aortic valve (AV); (3) mitral valve (MV) and (4) inferior wall (IW). The potential thrombus growth around the IC was assumed to be caused by blood stagnation regions with low velocity (<5 mm/s) and low shear rate (<60/s) flow. Mean velocity magnitudes and low blood velocity regions around the IC were numerically obtained. To quantitatively compare the thrombosis risks of the four simulation cases, the time-averaged volumes of the low-velocity regions and the low shear rate regions were calculated. The intraventricular volumes of low velocity zones based on IC orientation are 1.42 mL toward the septum, 1.14 mL toward the AV, 0.93 mL toward the MV, and 1.24 mL toward the IW. The intraventricular volumes of low shear regions based on IC orientation are 11.54 mL toward the septum, 11.15 mL toward the AV, 9.24 mL toward the MV, and 10.7 mL toward the IW. IC orientation toward the MV results in lower volumetric regions of low flow and low shear within the ventricle, which consequently may lead to a reduced risk of thrombus formation.

Continuous-Flow Left Ventricular Assist Device Support for Patients with Hypertrophic Cardiomyopathy: A Single Centre Experience

<h3>Purpose</h3> There is controversy over the use of durable left ventricular assist devices (LVADs) in supporting patients with hypertrophic cardiomyopathy (HCM) and advanced heart failure. HCM patients have smaller left ventricular (LV) dimensions and are at higher risk of LVAD inflow cannula occlusion from ventricular decompression. Right ventricular (RV) failure is also a concern in these patients. This study describes a single-centre experience of LVAD implantation in patients with heart failure due to HCM. <h3>Methods</h3> Cases were reviewed from a prospective registry of all LVAD implants at the University Health Network (Toronto, Canada) between 2006 and 2020 to identify patients with HCM. We determined baseline characteristics, peri-operative course and outcomes, including requirement for RV support, ICU and hospital length of stay and eventual outcome from LVAD support. <h3>Results</h3> We identified 15 patients with LVAD implantation for HCM with a history of heart failure of 6 (interquartile range: 4-12) years and peak VO₂ of 9.6 (9.2-10.4) ml/kg/min. Median age was 57 (46-60) years, 1 (7%) patient was female (Table). During the index admission for LVAD implant, 5 (33%) patients required renal replacement therapy and 3 (20%) died due to ischemic bowel, tracheobronchitis and liver failure/sepsis, respectively. No patients required RV support. ICU stay was 8 (6-11) days and hospital stay 33 (16-65) days in those discharged from hospital. Overall, patients were supported for 5153 patient-days; 9 (60%) patients underwent heart transplant after LVAD support of 206 (110-458) days, 2 (13%) are currently supported and 1 died after 1671 days from presumed pump thrombosis. One patient required LVAD exchange for late pump thrombosis. <h3>Conclusion</h3> This single-centre experience demonstrated that LVAD support in patients with HCM is safe and effective as a bridge to transplant or destination therapy. Further work should explore patient characteristics favourable to LVAD therapy in HCM patients.

More Than Just Suckdown: Hemodynamics of Intermittent Inflow Cannula Obstruction

<h3>Introduction</h3> Waveforms can provide important insights on patient hemodynamics after durable left ventricular assist device (LVAD) implantation. Herein we describe a case of LVAD implanted as BTC complicated by intermittent inflow cannula obstruction. <h3>Case Report</h3> A 55-year old male was admitted decompensated heart failure. He had a Heartware device implanted as a bridge to candidacy (BTC) due to pulmonary hypertension and ischemic cardiomyopathy. In the 8 months since LVAD implant, the patient had gained 25 kg weight and had struggled to maintain a euvolemic state. Examination revealed an elevated jugular venous pressure, normal VAD sounds, peripheral edema and mean arterial pressure of 88mmHg. Monitoring of the LVAD demonstrated abnormal waveforms suggestive of intermittent suction events (Panel 1A). The patient was transferred to the ICU for invasive monitoring and transesophageal echocardiography to allow a ramp study. The imaging and hemodynamic data confirmed occlusion of the LVAD inflow cannula on each cardiac cycle (B,C) at his existing VAD settings (2740 rpm). A ramp study revealed a paradoxical increase in right atrial pressure and no improvement in blood pressure at higher speeds (D). Thoracic CT imaging confirmed cannula malposition and review of LVAD log files determined that there had been an abrupt change in pulsatility two months after implant and there had been increasingly frequent suction events since. Surgical reintervention was considered, however, given the chronicity of the changes, the consensus was to list the patient for urgent transplantation. <h3>Summary</h3> We describe a case of covert suction events where increasing body mass by 25kg (41%) may have contributed. In LVAD patients who are challenging to decongest, waveforms, hemodynamic and imaging guided optimization can improve function and identify complications.

P820 Echocardiographic assessment of late-onset right ventricular dysfunction following continuous-flow left ventricular assist device

Abstract Early right ventricular failure (RVF) remains one of the main factors associated with early mortality following continuous-flow left ventricular assist device (LVAD) implantation. However, late-onset RVF (LoRVF) has emerged as an increasing concern, but little is known about its incidence rate and the value of transthoracic echocardiography (TTE) to predict this complication during the LVAD follow-up. Methods and results We retrospectively analyzed the 1-year hemodynamic and clinical data from patients (p) that, between 2016 and 2018, underwent a right heart catheterization (RHC) after LVAD as bridge to transplantation (BTT). 73 p (84% males, 52 ± 12 years, 49% Heart Ware LVAD, 51% Heart Mate 3 LVAD), out of 187 LVAD implants, were studied. According to the Intermacs definition, LoRVF was assigned if the RHC showed a central venous pressure (CVP)&amp;gt;18 mmHg with cardiac index&amp;lt; 2.3 L/min/m2. Isolated LoRVF was assigned if LoRVF was present in the absence of elevated pulmonary capillary wedge pressure (PCWP) ≤15 mmHg. TTE was performed at the time of the RHC and the following parameters were obtained: parasternal long-axis left ventricular end diastolic diameter (LVEDD), basal (RVED1) and mid-cavity (EDRV2) end diastolic RV linear dimension in 4 chamber view, severity of tricuspid regurgitation (TR) and of mitral regurgitation (MR), tricuspid annular plane systolic excursion (TAPSE), and the position of the LVAD inflow cannula (IC). LoRVF was present in 16 p (22% of the studied population): 12 p (75%) presented a PCWP &amp;gt; 15 mmHg and 4 p (25%) presented isolated LoRVF. Symptoms and signs of venous congestion were present in 2/3 of the p with LoRVF and elevated PCWP. On the other hand, all the p with isolated LoRVF presented severe signs of venous congestion, and 50% of them could be successfully transplanted in high urgent status. P with LoRVF showed more dilated RV (RVED1 43.8 ± 9.2 vs 37.7 ± 5.3 mm, p = 0.02) and lower TAPSE (11 ± 2 vs 14 ± 2 mm p &amp;lt; 0.01) than the no LoRVF group. RVED1 showed a weak significant correlation with CVP (R = 0.3, p = 0.02). On the other hand, the presence of an elevated PCWP was not related to etiology of the cardiomyopathy, type and speed of LVAD, position of the IC, LVEDD, nor the presence of MR &amp;gt; mild. Conclusion LoRVF is a frequent complication during LVAD support as BTT and most of the cases are associated with persistent elevated PCWP. Isolated LoRVF, which is not associated with high PCWP, has a bad prognosis. RV evaluation with TTE during the clinical follow-up can be useful to detect LoRVF. However a persistent elevated PCWP is not associated with echocardiographic signs of incomplete unloading of the LV by the LVAD.

Left Ventricular Assist Device Inflow Cannula Insertion Depth Influences Thrombosis Risk

Left ventricular assist device (LVAD) use has continued to grow. Despite recent advances in technology, LVAD patients continue to suffer from devastating complications, including stroke and device thrombosis. Among several variables affecting thrombogenicity, we hypothesize that insertion depth of the inflow cannula into the left ventricle (LV) influences hemodynamics and thrombosis risk. Blood flow patterns were studied in a patient-derived computational model of the LV, mitral valve (MV), and LVAD inflow cannula using unsteady computational fluid dynamics (CFD). Hundreds of thousands of platelets were tracked individually, for two inflow cannula insertion depth configurations (12 mm-reduced and 27 mm-conventional) using platelet-level (Lagrangian) metrics to quantify thrombogenicity. Particularly in patients with small LV dimensions, the deeper inflow cannula insertion resulted in much higher platelet shear stress histories (SH), consistent with markedly abnormal intraventricular hemodynamics. A larger proportion of platelets in this deeper insertion configuration was found to linger in the domain for long residence times (RT) and also accumulated much higher SH. The reduced inflow depth configuration promoted LV washout and reduced platelet SH. The increase of both SH and RT in the LV demonstrates the impact of inflow cannula depth on platelet activation and increased stroke risk in these patients. Inflow cannula depth of insertion should be considered as an opportunity to optimize surgical planning of LVAD therapy.

Association of LVAD Outflow Cannula Position with Stroke Risk

Background Stroke remains a major cause of morbidity and mortality in patients with left ventricular assist devices (LVAD). Although several studies have delineated clinical risk factors for development of stroke, it is not entirely clear whether changes in position/orientation of the LVAD cannula impact incidence of subsequent stroke. Hypothesis We hypothesized that variations in surgical implant techniques for LVAD inflow and outflow cannula positions impact the subsequent risk of stroke. Methods We conducted a retrospective review of all patients that underwent LVAD implantation at our institute between 2011 and 2016. All patients that underwent multi detector cardiac computed tomography (MDCT) were included in the analysis. Patients with non-contrast CT scans and poor imaging quality were excluded. Baseline demographic as well as clinical parameters were obtained for all patients. Inflow and outflow cannula positions were assessed by various MDCT parameters outlined in table 1. The incidence of stroke from time of implantation to one year post-LVAD implantation was obtained. Results A total of 311 continuous-flow LVADs were implanted at our hospital from 2011-2016, of which 75 patients met inclusion criteria for the study. The study population was predominantly HM II with only 3 HVAD and 1 HM 3 patients. 11 patients had stroke within 1 year of LVAD implantation. There were no significant differences in baseline demographic or clinical characteristics between patients that had stroke versus those that did not. Patients with stroke had more acute angulation of outflow cannula relative to the aorta compared to patients without stroke (42⁰ versus 65⁰ respectively, p= 0.026). In addition, patients with stroke had a smaller diameter of anastomosis of the outflow cannula compared to those without stroke (1.3 cm versus 1.5 cm respectively, p= 0.013). The inflow cannula position did not impact incidence of stroke. Conclusions Our study shows that LVAD outflow cannula orientation and size of anastomosis portend a higher risk of subsequent stroke. Therefore, it is imperative to optimize LVAD surgical implant techniques and device manufacturing to allow larger anastomosis site and less acute angulation of the outflow cannula.

Novel Formula to Calculate Three-Dimensional Angle Between Inflow Cannula and Device Body of HeartMate II LVAD

The acute angle between inflow cannula and device body of HeartMate II left ventricular assist device (LVAD) (Abbott, Pleasanton, California) is associated with device thrombosis. However, most studies utilized two-dimensional (2D) angle obtained from chest roentgenogram (CXR), which is unlikely accurate. We aimed to create and validate a formula to estimate actual three-dimensional (3D) angle. We retrospectively reviewed the cohort undergoing HeartMate II LVAD implantation between 2008 and 2016. A formula for calculating 3D angles of the LVAD inflow cannula relative to the device body was mathematically derived, using simple 2D measurements from CXR. The cohort included consecutive 275 patients with HeartMate II (median age: 60 [25% quartile: 51, 75% quartile: 68] years). There was no significant difference between the calculated 3D angles (from formula) and actual 3D angles (from computed tomography) from the subset group with 3D computed tomography (n= 28) (71.7° ± 13.4° vs 71.1° ± 11.5°, P= .858). Among all participants, the calculated 3D angle (from formula) was 74.4° ± 14.2°, which was significantly larger than the 2D projected angle (from CXR) (65.2° ± 11.3°, P < .001). There was no statistical difference in the calculated 3D angles (from formula) between patients with/without device thrombosis, hemorrhagic stroke, ischemic stroke, or mortality (P > .05 for all). We established a novel formula to mathematically calculate actual 3D angles between inflow cannula and device body of HeartMate II. The formula would help investigators to validate their findings of the relationship between 2D projected angle (from CXR) and device thrombosis.

Reducing regional flow stasis and improving intraventricular hemodynamics with a tipless inflow cannula design: An in vitro flow visualization study using the EVAHEART LVAD.

Due to the high stroke rate of left ventricular assist device (LVAD) patients, reduction of thrombus has emerged as an important target for LVAD support. Left ventricular blood flow patterns with areas of flow stasis and recirculation are associated with platelet aggregation, which is worsened by exposure to high shear stress. Previous reports of intraventricular thrombus in LVAD patients have identified the outside of the LVAD inflow cannula as a nidus for LV thrombus formation. Previous studies of LVAD inflow cannula design have shown a region of low blood velocity and pulsatility at the apex, adjacent to the cannula. One unresolved question is whether the standard practice of inserting the LVAD inflow cannula several mm into the LV could be revised to reduce thrombus formation. To address this, a "tipless" inflow cannula was designed for the EVAHEART LVAS, and assessed in a mock circulatory loop of the LVAD-supported heart. Customized transparent silicone models of a dilated LV were connected to the EVAHEART LVAS at the apex with a clear polycarbonate inflow cannula for flow visualization using particle image velocimetry (PIV). The "tipless" cannula was inserted flush with the endocardial border and did not protrude into the LV. This condition was compared to the standard cannula position with a 1-cm insertion into the LV. The Pre-LVAD condition corresponded to a severe heart failure patient (ejection fraction of 24%) with a dilated LV (180 mL). LVAD support was provided at speeds of 1.8 and 2.3 krpm. At the lower LVAD speed, 63% of the flow passed through the LVAD, with the remainder ejecting through the aortic valve. When LVAD speed was increased, nearly all flow (98%) left the LV through the LVAD. Both LVAD speed conditions produced a vortex ring similar to the Pre-LVAD condition in diastole. However, the protruding inflow cannula interrupted the growth and restricted the movement of the vortex, and produced areas of low velocity and pulsatility adjacent to the cannula. The tipless cannula exhibited an uninterrupted pattern of the mitral jet toward the LV apex, which allowed the diastolic vortex to grow and aid in the washout of this region. In addition, the tipless cannula increased aortic valve flow, which reduces stasis in the left ventricular outflow tract. The EVAHEART LVAS tipless inflow cannula design improved regional velocity, pulsatility, and vortex formation compared to the standard protruding design, which all reduce the risk of thrombus formation. The clinical significance of the differences observed in the flow field will be dependent on other factors such as the cannula material and surface characteristics, as well as the patients' coagulation status.

Association of Inflow Cannula Position with Left Ventricular Unloading and Clinical Outcomes in Patients with HeartMate II Left Ventricular Assist Device.

The relationship between the HeartMate II left ventricular assist device (LVAD) position and pump thrombosis has been reported. However, further clinical implications of device position are unknown. This study aimed to investigate optimal device position for better left ventricular (LV) unloading and patient prognosis. Patients undergoing a ramp test with right heart catheterization after HeartMate II LVAD implantation were enrolled to this study. Device position was quantified from the chest X-ray obtained at the time of the ramp test: (1) inflow cannula angle relative to horizontal line, (2) pump angle relative to spine, (3) pump depth, (4) angle between inflow cannula and pump, and (5) angle between pump and outflow graft. LV unloading was assessed by pulmonary capillary wedge pressure at set LVAD speed. Fifty-four patients (60 years old and 34 male [63%]) were enrolled. Nobody experienced device malfunction during the study period. Increased LV unloading (i.e., lower pulmonary capillary wedge pressure) was associated with a narrower inflow cannula angle relative to horizontal line. Inflow cannula angle <75° was associated with higher 1 year heart failure readmission-free survival rate (p < 0.05, hazards ratio 7.56 [95% confidence interval 2.32-24.7]). In conclusion, HeartMate II LVAD inflow cannula position was associated with LV unloading and patient prognosis. Prospective studies to ensure optimal device positioning and target better clinical outcomes are warranted.

Myocardial Irritation from a Left Ventricular Assist Device Resulting in Refractory Ventricular Tachycardia

BackgroundDue to an increasing prevalence of heart failure but a steady rate of heart transplantation, the number of left ventricular assist devices (LVADs) implanted is growing. These patients present to emergency departments (EDs) with a variety of complications from their implanted device as well as their baseline cardiomyopathy. One-third of patients will present with a dysrhythmia, the most common of which is ventricular tachycardia. Case ReportA 77-year-old man with nonischemic cardiomyopathy and HeartMate II LVAD presented with sustained ventricular tachycardia and 43 automatic implantable cardioverter-defibrillator (AICD) discharges. Due to left ventricular remodeling, ongoing diuresis, and positioning of his LVAD inflow cannula against his interventricular septum, a likely dysrhythmogenic foci, he quickly decompensated with sedation while in the ED. Why Should an Emergency Physician Be Aware of This?Refractory ventricular tachycardia is a common dysrhythmia for LVAD patients and may lead to full cardiopulmonary arrest. Common strategies such as chest compressions are used only in limited scenarios, but medical management is possible. This should focus on resolution of the dysrhythmia and identification of the etiology, including possible mechanical compromise.

Left Ventricular Assist Device Inflow Cannula Angle and Thrombosis Risk.

As heart failure prevalence continues to increase in the setting of a static donor supply, left ventricular assist device (LVAD) therapy for end-stage heart failure continues to grow. Anecdotal evidence suggests that malalignment of the LVAD inflow cannula may increase thrombosis risk, but this effect has not been explored mechanistically or quantified statistically. Our objective is to elucidate the impact of surgical angulation of the inflow cannula on thrombogenicity. Unsteady computational fluid dynamics is used in conjunction with computational modeling and virtual surgery to model flow through the left ventricle for 5 different inflow cannula angulations. We use a holistic approach to evaluate thrombogenicity: platelet-based (Lagrangian) metrics to evaluate the platelet mechanical environment, combined with flow-based (Eulerian) metrics to investigate intraventricular hemodynamics. The thrombogenic potential of each LVAD inflow cannula angulation is quantitatively evaluated based on platelet shear stress history and residence time. Intraventricular hemodynamics are strongly influenced by LVAD inflow cannula angulation. Platelet behavior indicates elevated thrombogenic potential for certain inflow cannula angles, potentially leading to platelet activation. Our analysis demonstrates that the optimal range of inflow angulation is within 0±7° of the left ventricular apical axis. Angulation of the inflow cannula >7° from the apical axis (axis connecting mitral valve and ventricular apex) leads to markedly unfavorable hemodynamics as determined by computational fluid dynamics. Computational hemodynamic simulations incorporating Lagrangian and Eulerian metrics are a powerful tool for studying optimization of LVAD implantation strategies, with the long-term potential of improving outcomes.

Effect of Ventricular Arrhythmia Ablation in Patients With Heart Mate II Left Ventricular Assist Devices: An Evaluation of Ablation Therapy.

Patients with advanced heart failure (HF) are predisposed to ventricular arrhythmias (VAs), particularly following implantation of a left ventricular assist device (LVAD). There is minimal evidence for appropriate management strategies. This study aimed to compare the burden of VA and response to ablation performed either before or following LVAD implantation. We created a retrospective cohort of patients who underwent both VA ablation and Heart Mate II (Thoratec, Pleasanton, CA, USA) LVAD implantation at Mayo Clinic (Rochester, MN, USA). Patients were stratified based on whether they underwent VA ablation before (pre-LVAD) or after LVAD (post-LVAD) implantation. Descriptive analyses assessed 6-month arrhythmia burden in relation to LVAD implantation and VA ablation. A total of 9 patients underwent both LVAD implantation and VA ablation. There were 3 and 6 patients, respectively, in the pre-LVAD and post-LVAD cohorts. Among patients in the pre-LVAD cohort, the median number of VAs tended to increase after ablation (9 vs. 72) and decreased after LVAD implantation (72 vs. 63). Similarly among patients in the post-LVAD cohort, the median burden of VAs increased after LVAD implantation (1 vs. 22) and the median burden decreased after ablation (22 vs. 13). Two of 6 patients had substrate related to the LVAD inflow cannula site, while other substrate was not related directly to the cannula. In patients with progressive HF and LVAD implantation, ablation is associated with reduced VA rates. In LVAD patients, most VAs arise from substrate unrelated to the inflow cannula site.

Left ventricular assist device implantation in patients after left ventricular reconstruction.

Left ventricular assist device (LVAD) implantation can be challenging in patients with a prior surgical ventricular restoration (SVR). In this case series of heart failure patients with a history of SVR, we describe the surgical technique and outcome of a customized approach for inflow cannula orientation. Seven patients with a history of SVR with end-stage chronic heart failure were accepted for long-term LVAD support. In all patients, the Dacron patch was removed through left ventriculotomy and a Hegar 22 dilator was inserted at the estimated optimal position of the LVAD inflow cannula. The left ventricle was reconstructed around the dilator from the left ventricular (LV) apex to the base. Finally, the LVAD sewing ring was sutured onto the remaining apical defect and a HeartWare® LVAD was implanted. LVAD implantation was successful in all 7 patients. Transoesophageal echocardiography ensured an adequate LVAD position and inflow and outflow cannula Doppler flow recordings. The mean intensive care unit stay was 5.8 ± 2.6 days, and the hospital stay after surgery was 32 ± 16 days. All patients follow regular visits (follow-up 20 ± 16 months) at the outpatient clinic without any remarkable event. Using the technique described, LVAD implantation in patients after SVR is feasible and safe.

Proposing a novel technique to exclude the left ventricle with an assist device: insights from 4-dimensional flow magnetic resonance imaging.

Left ventricular assist device (LVAD) implantation has become an effective treatment for end-stage heart failure patients. However, LVAD support disrupts the natural intracavitary blood flow path through the heart, introducing flow patterns potentially associated with thrombosis especially around the inflow cannula. We present initial insights into in vitro 4D flow magnetic resonance imaging (MRI)-based analysis of flow patterns and an enzyme-activated milk test in a porcine left ventricular (LV) model during LVAD support, in a standard implant technique and in combination with a novel cone-shaped LV sparing prosthesis. 4D MRI of an LVAD-supported ex vivo porcine heart failure model was performed in a mock circulatory loop with an LVAD flow of 4.5 l/min. Two separate sets of hearts with an MR-compatible LVAD inflow cannula were used: one with a standard inflow via the pulmonary veins into the LV, one sparing the LV with the cone-shaped prosthesis sutured to the mitral annulus and the LVAD inflow cannula sparing the LV cavity. In correlation, an enzyme-activated milk test was performed to reveal locations of disturbed flows. Data were analysed visually and by performing a case-by-case analysis of flow patterns and enzyme activation locations. Using 4D flow MRI, the standard implant technique showed markedly altered flow patterns with flow velocity reduction in the LV cavity especially around the inflow conduit. The average flow velocity in the LV cavity was 12.8 ± 2.9 m/s. In contrast, the LV-sparing technique with a cone-shaped prosthesis showed faster and more organized flow of 36.3 ± 7.2 m/s on average to the LVAD inflow cannula. Compared with the standard technique, no recirculating blood flow components were detected. The enzyme-activated milk test confirmed the location and extent of helical and vertical flow patterns. For the first time, intracardiac flows in an LVAD setting have been shown in vitro based on a mock porcine ex vivo heart failure model by applying 4D flow MRI. Differences in flow characteristics of the same model using a prosthesis sparing the LV cavity are encouraging to further investigate their potential to reduce potential LVAD-associated side-effects, such as intracavitary clotting and its sequelae.

Percutaneous Fluoroscopic-Guided Endomyocardial Delivery in an Experimental Model of Left Ventricular Assist Device Support.

Endomyocardial delivery in the setting of active left ventricular assist device (LVAD) support has rarely been studied. The objective was to establish a protocol for endomyocardial injections during LVAD support without compromising mechanical circulation. LVAD implantation was performed in four pigs. A curved needle catheter was percutaneously inserted into the right carotid artery and positioned into the left ventricle under fluoroscopic guidance. In the setting of increasing LVAD flows (2.3-3.1 l/min), percutaneous methylene blue dye administration into the myocardium proceeded without complications in all pigs. Transection of excised hearts revealed an anterior, lateral, inferior, and septal wall distribution of methylene blue documenting injections in all four regions of the left ventricle. Ex vivo, the catheter could be maneuvered close to the LVAD inflow cannula despite augmentation of LVAD flow up to 5 l/min. Endomyocardial injections during LVAD support was found to be feasible and safe with the curved needle catheter.

(576) - Detailed Endocardial Mapping Around the Left Ventricular Assist Device Inflow Cannula Facilitates Successful Ablation of Ventricular Tachycardia

Ventricular tachycardia (VT) is an important cause of morbidity after left ventricular assist device (LVAD) implantation. We sought to demonstrate feasibility and efficacy of VT ablation in this population, and to determine how often ablation is required around the LVAD inflow cannula.

LVAD inflow cannula covered with a titanium mesh induces neointimal tissue with neovessels.

Thrombus formation at the interfaces of inflow cannulas and left ventricular apexes is considered to be one of the predominant sources of thromboembolic complication. Use of a fine titanium mesh-covered inflow cannula is expected to prevent such thrombus formation by inducing neointimal tissue around the cannula. Titanium pins (20 mm long, 3 mm diameter) covered with a fine titanium mesh (wire dia. 85 μm; volumetric porosity 40-70%) were developed to mimic the inflow cannulas of left ventricular assist devices (LVADs). Smooth-surface pins of the same size were also designed. The pins were implanted into the left ventricular apexes of rabbits. The rabbits were bled without anticoagulation for between 1 week and 1 year. The tissues around the pins were evaluated histologically. 28 rabbits (mesh group, 15; smooth group, 13) were evaluated. The mesh-covered pins inhibited thrombus formation to a remarkable degree throughout the entire observation period. The tissues around the mesh-covered titanium pins appeared to be in the process of conversion from thrombus formation to granulation, resulting in the replacement of fibrotic tissue containing myofibroblasts with endothelialized and angiogenic tissue. On the surface of the mesh-covered pins, endothelial cells were arranged without platelet adhesion. The tissue formed around the smooth-surface pins was partially organized into a thrombus without angiogenesis. The titanium-mesh surface modification prevented thrombus formation with formation of neointimal tissue with endothelialization and angiogenesis. This surface modification could prevent wedge thrombus formation among patients supported by LVADs.