Setting Of Left Ventricular Assist Device Research Articles

Pulmonary artery pulsatility index as a predictor of right ventricular failure in left ventricular assist device recipients: A systematic review.

It is critical to identify patients at increased risk of right ventricular failure (RVF) before left ventricular assist device (LVAD) implantation. Pulmonary artery pulsatility index (PAPi) is a hemodynamic parameter that is a specific measure of right ventricular function and may better identify LVAD recipients at risk for RVF. This systematic review analyzes the predictive value of preoperative PAPi to RVF in the setting of LVAD implantation. Databases were searched for all studies reporting on PAPi and RVF after LVAD implantation. Data collected included: number of patients, patient characteristics, incidences of RVF, PAPi, central venous pressure (CVP), CVP/pulmonary capillary wedge pressure, tricuspid annular plane systolic excursion, and right ventricular stroke work index. Thirty-two studies (4,756 patients) were included in this review. The incidence of RVF was found to be 27.48% (1,307 patients). The weighted mean (standard deviation) of preoperative PAPi associated with RVF vs No RVF was 2.17 (2.36) and 2.87 (3.21), respectively. When comparing LVAD recipients with RVF and No RVF, patients who developed RVF had a significantly lower preoperative PAPi by a WMD (95% CI) of -0.74 [-1.00, -0.49] (p < .001). The remaining variables (CVP; CVP/pulmonary capillary wedge pressure; tricuspid annular plane systolic excursion; and right ventricular stroke work index) were also confirmed as predictors of RVF after LVAD implantation. This systematic review demonstrates the utility of PAPi as a clinical predictor of RVF after LVAD implantation. Based on our findings, we recommend that PAPi be used in conjunction with traditional hemodynamic parameters when risk stratifying LVAD recipients for RVF.

Variation in CardioMEMS Pressure Measurements Due to Frequent Changes in Altitude in a Patient with HeartMate III LVAD

Introduction Implantation of a wireless pulmonary artery pressure monitoring device [CardioMEMS] has been utilized to monitor hemodynamic parameters in patients with NYHA Class III heart failure, however the impact of travel between altitudes on device calibration in patients who have received the Heart Mate III (HM3) Left Ventricular Assist Device (LVAD) is unknown. We describe a case of poorly correlating CardioMEMS readings with Swan-Ganz catheter measurements in a patient requiring frequent travel. Case Report A 53 year old man underwent placement of a CardioMEMS device 4 months prior to placement of a HM3 LVAD for stage D non-ischemic cardiomyopathy and was noted to have significant increases in the device's pulmonary arterial pressure readings. The patient was clinically stable and well compensated with stable LVAD settings and no alarms were noted. His chest X-ray showed stable position of his CardioMEMS device, clear lung fields, and a stable LVAD device position. Pulmonary artery waveform on the CardioMEMS device was normal. Repeat right heart catheterization at his home institution showed significant discrepancy between Swan-Ganz catheter measurements and his CardioMEMS readings. The difference in mean pulmonary artery pressure was roughly 15 mmHg. The device had been auto-calibrated at a different institution that was 3996 ft (1217 m) higher in altitude. The patientʼs travel between institutions continued due to active transplant evaluation and the CardioMEMS auto re-calibrated to the higher altitude setting despite recalibration twice at the home institution. The decision was made to turn off his CardioMEMS and monitor the patient clinically. Summary CardioMEMS device implantation can assist in remote monitoring of heart failure patients with LVADs. Accuracy of the device may be affected by large changes in elevation between the initial baseline calibration and subsequent measurements (2mm Hg per 305 meters elevation change) in patients without an LVAD per the device manufacturer. This case highlights the importance of considering changes in elevation of different geographic calibration locations as potential causes for error in CardioMEMS pressure readings prior to adjustment of medications. Further investigation is needed to evaluate changes in CardioMEMS pressure readings as it correlates to changes in altitude in LVAD patients.

Sacubitril-valsartan Improves Blood Pressure And Heart Failure In Left Ventricular Assist Device (lvad) Patients

Purpose Angiotensin receptor neprilysin inhibitors (ARNIs) are not routinely used in patients following left ventricular assist device (LVAD) implantation. At our center, we have increasingly adopted ARNI use in LVAD patients. The objective of this study was to investigate the effects of ARNI therapy on LVAD patients. Methods Stable LVAD outpatients with hypertension and persistent heart failure in spite of standard LVAD optimization were initiated on ARNI therapy at our center. We retrospectively reviewed medication requirements and clinical parameters pre- and 3-months post-ARNI initiation. Results Twenty-one LVAD outpatients were initiated on sacubitril-valsartan in an effort to improve blood pressure control and heart failure symptoms. Of these 20 patients, 10 (50%) were maintained on 24/26 mg BID dosing, 6 (30%) were uptitrated to 49/51 mg BID, and 4 (20%) to 97/103 mg BID. Three months following ARNI initiation, mean arterial pressure improved from 92±24 to 75±19 mm Hg (P Conclusion ARNI can improve blood pressure, decrease diuretic requirement, and functional capacity in LVAD patients. LVAD speed and medication adjustments may be necessary following ARNI initiation, and in some instances, side effects can limit the ability to sustain ARNI therapy in the setting of LVAD.

Intraventricular Flow Patterns in Patients Treated with Left Ventricular Assist Devices.

The success of left ventricular assist device (LVAD) therapy is hampered by complications such as thrombosis and bleeding. Understanding blood flow interactions between the heart and the LVAD might help optimize treatment and decrease complication rates. We hypothesized that LVADs modify shear stresses and blood transit in the left ventricle (LV) by changing flow patterns and that these changes can be characterized using 2D echo color Doppler velocimetry (echo-CDV). We used echo-CDV and custom postprocessing methods to map blood flow inside the LV in patients with ongoing LVAD support (Heartmate II, N = 7). We compared it to healthy controls (N = 20) and patients with dilated cardiomyopathy (DCM, N = 20). We also analyzed intraventricular flow changes during LVAD ramp tests (baseline ± 400 rpm). LVAD support reversed the increase in blood stasis associated with DCM, but it did not reduce intraventricular shear exposure. Within the narrow range studied, the ventricular flow was mostly insensitive to changes in pump speed. Patients with significant aortic insufficiency showed abnormalities in blood stasis and shear indices. Overall, this study suggests that noninvasive flow imaging could potentially be used in combination with standard clinical methods for adjusting LVAD settings to optimize flow transport and minimize stasis on an individual basis.

Significance of Aortic Valve Insufficiency with Left Ventricular Assist Device: Duration and Regurgitant Flow in a Mock Loop Study

In patients with left ventricular assist device (LVAD), aortic valve insufficiency (AI) could occur in longer period during the cardiac cycle, throughout the diastolic and part of the isovolumetric phases. As the result, the current echocardiographic evaluation of AI grade may underestimate the degree of AI in LVAD patients, especially those with significant AI. In this study, we investigated the differences in AI duration and regurgitant volume before and during LVAD supports (Off and On LVAD) using a mock circulatory loop. All measurements were performed using a mock circulatory system with a dilated silicone LV model attached to a HeartMate II LVAD (Abbott Lab), and pressure and flow measured in the LV, LVAD, and aorta. Baseline condition was established as no LVAD condition (Off LVAD setting) which has 17% ejection fraction, 62 bpm heart rate and 65 mmHg systemic pressure. LVAD condition (On LVAD setting) at 8,800 rpm with same ejection fraction, heart rate and systemic resistance (90 mmHg systemic pressure) was established, followed by testing at three AI severity conditions. AI severity was defined as mild, moderate, or severe based on effective regurgitant orifice area. AI conditions were created with small 3-D printed stents, which were nonobstructive to forward flow, but prevented the leaflets from fully closing. AI durations and regurgitant volumes were determined from the calculated backward flow through the aortic valve. With the constant systemic resistance in the On LVAD setting at 8,800 rpm, duration of AI increased by 8.3 % (75 to 83.3%) with mild AI, 5.6% (77.8 to 83.3%) with moderate AI, and 5.6% (77.8 to 83.3%) with severe AI compared to the Off LVAD setting. With the constant systemic resistance in the On LVAD setting at 8,800 rpm, regurgitant volume of AI increased by 0.11 L/min (0.12 to 0.23 L/min, 92%) in mild AI, 0.03 L/min (0.53 to 0.56 L/min, 5.7%) in moderate AI and 0.08L/min (0.78 to 0.86 L/min, 10.3%) with severe AI compared to the Off LVAD setting. This mock loop study demonstrated that AI duration was longer and regurgitant volume through the aortic valve was greater during LVAD support compared to same AI degree before LVAD. This suggests that clinical burden of AI may be underestimated in patients with LVAD.

Sacubitril-Valsartan Improves Blood Pressure and Heart Failure in Left Ventricular Assist Device (LVAD) Patients

Angiotensin receptor neprilysin inhibitors (ARNIs) are not routinely used in patients following left ventricular assist device (LVAD) implantation. At our center, we have increasingly adopted ARNI use in LVAD patients. The objective of this study was to investigate the effects of ARNI therapy on LVAD patients. Stable LVAD outpatients with hypertension and persistent heart failure symptoms were initiated on ARNI therapy at our center. We retrospectively reviewed medication requirements and clinical parameters pre- and 3-months post-ARNI initiation. Twenty stable LVAD outpatients were initiated on sacubitril-valsartan in an effort to improve blood pressure control and heart failure symptoms. Of these 20 patients, 10 (50%) were maintained on 24/26 mg BID dosing, 6 (30%) were uptitrated to 49/51 mg BID, and 4 (20%) to 97/103 mg BID. Three months following ARNI initiation, mean arterial pressure improved from 92±24 to 75±19 mm Hg (P<0.001). ARNI allowed for significant dose reduction in calcium channel blocker dose burden (nifedipine 56±60 to 30±48 mg/day, P=0.02; amlodipine 3±4 to 0±2 mg/day, P=0.06). ARNI also facilitated a significant reduction in loop diuretic requirement (furosemide equivalent of 132±136 to 80±65.6 mg/day, P=0.004). There was an overall improvement in New York Heart Association Functional Class (2.6±0.8 to 1.6±0.7, P<0.001). Renal function did not appreciably change (Creatinine 1.3±0.5 to 1.3±0.3 mg/dl, P=0.76). There was a trend towards reduced left ventricular diastolic diameter (6.1±1.0 to 5.7±1.1 cm, P=0.13). Six patients experienced an unremitting side effect requiring ARNI cessation (dizziness/hypotension, 3; LVAD suction, 2; cough, 1). ARNI can improve blood pressure, decrease diuretic requirement, and improve functional capacity in LVAD patients. LVAD speed and medication adjustments may be necessary following ARNI initiation, and in some instances, side effects can limit the ability to sustain ARNI therapy in the setting of LVAD.

Clinical Approach to Manage Gastrointestinal Bleeding with a Left Ventricular Assist Device (LVAD).

Left ventricular assist devices (LVADs) are an exceedingly important form of mechanical support for patients with end-stage heart failure. LVADs can be utilized both as a bridge to cardiac transplant and also as a definitive treatment. However, a few complications are associated with LVAD placement, the most common and cumbersome of which is gastrointestinal (GI) bleeding with an incidence of about 30%. These bleeding events often require transfusion therapy, but they are rarely fatal.The etiologies of GI bleeding following LVAD are multifactorial and include unstable hemodynamics, an acquired von Willebrand factor (vWf) deficiency, impaired platelet aggregation, and activation of fibrinolytic systems. The treatment of choice in LVAD implantation-associated GI bleeding is endoscopy, which plays a vital role in both its diagnosis and management. Even so, its effectiveness in controlling post-LVAD implantation GI bleeding is still poorly ascertained. In this article, we will review the use of medication and alterations in the LVAD setting to prevent the occurrence of GI bleeding, as well as the findings of previously reported literature on LVAD implantation-associated GI bleeding.

586 Investigation of Gastrointestinal Bleeding Among Left Ventricular Assist Device Recipients

INTRODUCTION: Left ventricular assist device (LVAD) therapy is a form of mechanical support for patients with advanced heart failure as either a bridge to heart transplant or destination therapy. The association between gastrointestinal bleeding (GIB) and LVAD recipients is well established. There has been reported literature comparing demographics and clinical associations between patients with and without GIB. The aim of this study was to further investigate these characteristics, identify associations with GIB, and further understand endoscopic management of GIB among LVAD recipients. METHODS: This was a single-center retrospective study analyzing randomly selected patients from a population of 425 Heartmate (HMII) and 193 Heartware recipients from 2007 to 2018. Chart review was performed and data pertaining to demographics, LVAD therapy intention and settings, endoscopic reports, home medications, and echocardiogram reports was collected. Univariate analysis was performed. RESULTS: A total of 188 HMII and 134 Heartware patients were included in this study. Patients that developed GIB tended to be older (56.4 vs. 61.7 years; P = 0.0002). No differences were found in race and gender. Patients that developed a GIB had a higher baseline Cr (1.2 vs. 1.4; P = 0.0284) and lower baseline Hg (10 vs. 11; &lt;0.001). A supratherapeutic INR was associated with GIB (14.7% vs. 26.7%; P = 0.0075). Patients prescribed angiotensin II receptor blockers had less occurrence of GIB (Table 1). Melena was the most common presenting sign. Bleeding lesions were most frequent in the small bowel (42.6%). Of all bleeding lesions identified, 73% were found with EGD and 80.4% were found with push enteroscopy. Arteriovenous malformations were the predominant etiology (Table 2). CONCLUSION: This is one of the largest single-center studies of GIB among patients with LVADs. Small bowel gastric arteriovenous malformations were the most common etiology. The majority of upper GI bleeds were within reach of a push enteroscope (proximal small bowel), which had an incremental diagnostic yield over EGD. There was a protective association with reduced occurrence of GIB among patients taking angiotensin II receptor blockers. The use of proton pump inhibitors showed no association in GIB occurrence and may be overused in this population. Further development of the association between angiotensin II receptor blockers and GIB effect in LVADs are warranted. Multivariate analyses to validate these associations are in progress.

Ventricular Energetics in Pediatric Left Ventricular Assist Device Patients: A Retrospective Clinical Study.

The aim of this study is to estimate the trend of right and left energetic parameters in left ventricular assist device (LVAD) pediatric patients. Echocardiographic data were retrospectively collected at the baseline, in the acute phase after and at the monthly follow-ups till the LVAD explantation to estimate left and right ventricular energetic parameters. A significant relationship between the left and right ventricular energetic parameter trends was found along all the study period. Left ventricular end-systolic pressure-volume relationship improved till the follow-up of 2 months and then progressively decreases. Left arteroventricular coupling decreases after the LVAD, and right arteroventricular coupling decreases at the short-term follow-up. Left ventricular external work, potential energy, and pressure-volume area decrease at the short-term follow-up and then increase progressively. Right ventricular external work, potential energy, and pressure-volume area increase after the LVAD implantation. Left (right) cardiac mechanical efficiency is improved (worsened) by the LVAD. Energetic variables show that the LVAD benefits could decrease over time. A continuous and patient tailored LVAD setting could contribute to prolong LVAD benefits. The introduction of energetic parameters could lead to a more complete evaluation of LVAD patients' outcome which is a multiparametric process.

Management of Patients With Left Ventricular Assist Devices Requiring Teeth Extraction: Is Halting Anticoagulation Appropriate?

An increasing number of patients with end-stage heart failure are supported with left ventricular assist device (LVAD) implantation and must be maintained on a consistent anticoagulation regimen. Pre-emptive extraction of carious teeth in these patients is necessary to prevent seeding of the implanted device and endocarditis. Thus, the objective of this study was to evaluate bleeding complications after minor oral surgery, specifically teeth extractions, in this unique patient population requiring long-term anticoagulation. This study was a retrospective single-center review. Adult patients supported on an implanted continuous-flow LVAD from January 1, 2007 to December 31, 2016 were included. Baseline characteristics were collected by retrospective chart review and the institutional LVAD registry. All extractions were performed in the operating room under local anesthesia with moderate sedation or general anesthesia with nasal intubation, and LVAD settings were monitored by a trained perfusionist. Preoperative and postoperative hematology laboratory values, such as hemoglobin and international normalized ratio (INR), were collected by chart review. Continuous variables were presented as mean±standard deviation and compared using the Student t test. Categorical variables were presented as proportion and percentage and compared using the χ2 test or Fisher exact test as appropriate. Statistical significance was established at a P value less than .05. After screening 798 patients, 32 (4%) were found to have undergone dental extractions after LVAD implantation. The sample was composed of 32 patients with a mean age of 60.13years and 81.25% were men. The average time from LVAD implantation to extraction was 445.19±1,108.53days. Average preoperative INR was 1.76±0.47. Preoperative fresh frozen plasma was not administered to any patients. Twenty-eight patients (87.5%) were on Coumadin (warfarin) preoperatively. In 11 of these 28 patients (39.3%), Coumadin was held preoperatively. The average postoperative change in hemoglobin level was -0.79±1.45. Only 1 patient (3%) required postoperative blood transfusion for a hemoglobin level of 7.6 that responded appropriately. There were no reoperations for bleeding. Minor oral surgical procedures can be performed safely for patients being supported on LVAD therapy. With primary closure of the gingiva at the site of extraction, dental extractions can be performed without the full reversal of anticoagulation.

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.

Left Ventricular Assist Device Management in the ICU

To review left ventricular assist device physiology, initial postoperative management, common complications, trouble shooting and management of hypotension, and other common ICU problems. Narrative review of relevant medical literature. Left ventricular assist devices prolong the lives of patients with end-stage heart failure, and their use is increasing. Continuous-flow left ventricular assist devices have replaced first-generation pulsatile devices. These patients present unique management concerns. In the immediate postimplant period, care must be taken to support the unassisted right ventricle. Invasive monitors for blood pressure, pulmonary artery catheterization, and echocardiography are essential to optimize left ventricular assist device settings and cardiac performance. Anticoagulation is necessary to prevent devastating thrombotic and embolic complications, but bleeding is a major source of morbidity due to inherent bleeding diatheses and prescribed anticoagulants. Infection of the device can be life threatening, and all infections must be aggressively treated to avoid seeding the device. Patients are at risk of ventricular arrhythmias because of their underlying disease, as well as the placement and position of the inflow cannula. Aortic valve stenosis and insufficiency develop over time and can lead to thrombosis or heart failure. Cardiopulmonary resuscitation with chest compressions must be performed with care or not at all due to risk of dislodging the device. Intensivists are increasingly likely to encounter patients requiring mechanical circulatory support with left ventricular assist devices at various points in the trajectory of their disease, from the immediate postimplant period to subsequent admissions for complications, and at end of life. A basic understanding of left ventricular assist device physiology is essential to the safe and effective care of these patients.

Monitoring of Aortic Valve Opening and Systolic Aortic Insufficiency in Optimization of Continuous-Flow Left Ventricular Assist Device Settings

AORTIC INSUFFICIENCY (AI) in patients after left ventricular assist device (LVAD) implantation is one of the unintended and potentially harmful consequences. 1 Frazier O.H. Unforeseen consequences of therapy with continuous-flow pumps. Circ Heart Fail. 2010; 3: 647-649 Crossref PubMed Scopus (31) Google Scholar , 2 Cowger J. Pagani F.D. Haft J.W. et al. The development of aortic insufficiency in LVAD supported patients. Circ Heart Fail. 2010; 3: 668-674 Crossref PubMed Scopus (273) Google Scholar Excessive LVAD flows, resulting in diminished and infrequent aortic valve (AV) opening, may facilitate AI progression and extend its duration to the systolic phase of the cardiac cycle. 2 Cowger J. Pagani F.D. Haft J.W. et al. The development of aortic insufficiency in LVAD supported patients. Circ Heart Fail. 2010; 3: 668-674 Crossref PubMed Scopus (273) Google Scholar , 3 Hatano M. Kinugawa K. Shiga T. et al. Less frequent opening of the aortic valve and a continuous flow pump are risk factors for postoperative onset of aortic insufficiency in patients with a left ventricular assist device. Circ J. 2011; 75: 1147-1155 Crossref PubMed Scopus (89) Google Scholar The high temporal resolution of the echocardiographic M mode makes it very effective in monitoring the effects of LVAD speeds on AV function in real time. This case report describes the pathophysiology of AV leaflets akinesis and systolic aortic insufficiency in patients supported with continuous-flow LVAD and shows the grayscale and color M-mode AV surveillance in the perioperative optimization of the LVAD setting.

Derived and Displayed Power Consumption, Flow, and Pulsatility Over a Range of HeartMate II Left Ventricular Assist Device Settings

Continuous-flow left ventricular assist devices/systems (LVADs/LVASs) reduce symptoms and mortality in severe heart failure. The impeller or centrifugal designs provide challenges in assessing and titrating pump speed (revolutions per minute [RPM]), flow, and native heart pulsatility, and contribution to cardiac output. The Thoratec HeartMate II (HM II) LVAS is the most commonly used LVAD worldwide. The user sets the RPM and the monitor provides online data on RPM, power consumption, flow, and pulsatility. These parameters are routinely used by clinicians to assess native heart function and to optimize pump settings. However, little is known about their reliability, reproducibility, and variability. Therefore, we assessed HM II controller parameters and concurrent echocardiography during titrations of RPM to low and high values. We found that data displayed on the monitor and logged in the controller are consistent for power consumption and for flow at settings above 8,000 RPM but inconsistent and unreliable for flow at or below 8,000 RPM and for pulsatility throughout a range of common settings and specifically at 9,000 RPM. These findings have implications for clinicians attempting to optimize settings and assess pump and native heart function.

Echocardiographic Variables After Left Ventricular Assist Device Implantation Associated With Adverse Outcome

Background— Operative mortality after left ventricular assist device (LVAD) implantation is heavily influenced by patient selection and the technical difficulty of surgery. However, how we treat our patients and LVAD setting may affect the patient outcome beyond this period. We postulated that the presence of echocardiographic variables 1 month after surgery suggesting appropriate degree of LV unloading and an adequate forward flow would be important in determining clinical outcomes after the initial successful LVAD implantation. Methods and Results— We retrospectively analyzed various variables in echocardiographic examinations performed 30 days after LVAD implant in 76 consecutive patients receiving continuous flow device for their association with a compound end point (90-day mortality, readmission for heart failure, or New York Heart Association class III or higher at the end of the 90-day period). The echocardiographic associations examined included estimated LVAD flow, with and without native LV contribution, interventricular septal position, the status of aortic valve opening, an estimated left atrial pressure (ELAP), the mitral flow E-wave deceleration time, and the ratio of deceleration time to E-wave velocity (mitral deceleration index [MDI]). Four patients died during the 30- to 90-day period, 6 patients were readmitted for heart failure, and 25 patients were considered to have New York Heart Association class III or higher at the end of the 90-day period. Variables associated with adverse outcome included increased ELAP (odds ratio, 1.30 [1.16–1.48]; P &lt;0.0001), MDI &lt;2 ms/[cm/s] (odds ratio, 4.4 implantation [1.22–18]; P =0.02) and decreased tricuspid lateral annulus velocity (odds ratio, 0.70 implantation [0.48–0.95]; P =0.02). A leftward deviation of interventricular septum was associated with a worse outcome (odds ratio, 3.03 implantation [1.21–13.3]; P =0.01). Conclusions— Mortality and heart failure after LVAD surgery appear to be predominantly determined by echocardiographic evidence of inefficient unloading of the left ventricle and persistence of right ventricular dysfunction. Increased estimated LA pressure and short MDI are associated with worse mid term outcome. Leftward deviation of the septum is associated with worse outcome as well.

276 Demonstration of Hypercoagulability after Implantation of the HeartWare Ventricular Assist Device by Using Thromboelastography

Purpose: Consensus regarding the optimal strategy for setting left ventricular assist device (LVAD) speed has not been achieved, and optimal settings may differ between rest and exercise. We report a method for LVAD optimization at rest and with low intensity exercise using gas exchange analysis. Methods and Materials: 11 patients 3 months following implant of HeartMate II LVAD were studied using the SHAPE System (Shape Medical Systems, St. Paul, MN), which has previously been used for cardiac resynchronization therapy (CRT) optimization using gas exchange analysis. Five LVAD speeds were tested in each patient (clinically set baseline, 400, 200, 200, and 400 rpm); both at rest and with low intensity treadmill exercise (1-2 mph with 0-1% grade). Continuous partial pressure of end-tidal carbon dioxide (PETCO2) and ventilatory drive (defined as tidal volume/inspiratory time [VT/Ti]) were measured at each condition at two-minute increments; data from the last 30 seconds of each stage were analyzed. Results: Mean differences detected in PETCO2 and ventilatory drive were 2.1 0.8 mm Hg and 127 64 mL/s at rest and 2.0 0.8 mm Hg and 188 78 mL/s with exercise, respectively. There was poor agreement between clinically selected speed setting with “optimal” PETCO2 and VT/Ti-based settings. The clinical setting matched the “optimal” PETCO2 and VT/Ti setting in only 2/11 and 0/11 of patients at rest, and 3/11 and 7/11 of patients during exercise, respectively. On a per-patient basis, PETCO2 and VT/Ti-based optimal settings correlated in 7/11 of patients at rest and 5/11 during exercise. Using gas exchange-based optimization it was noted that the optimal setting at rest and exercise was different in 9/11 patients using either PETCO2 or VT/Ti. Conclusions: This pilot study suggests that gas exchange-based LVAD optimization can discriminate physiologically significant differences in gas exchange, and is frequently different than clinically determined settings. Furthermore, optimal LVAD settings at rest and with exertion often differ when measured objectively using gas exchange.

Overdrive Pacing Suppresses Ectopy and Minimizes Left Ventricular Assist Device Suction Events

20-year-old man with idiopathic dilated cardiomyopathy underwent placement of a HeartMate II (Thoratec Corporation, Pleasanton, Calif) axial-flow left ventricular assist device (LVAD) as a bridge to cardiac transplant. The immediate postoperative phase was without complications. The LVAD was initially set at 8500 rpm. Under echocardiography guidance, a ramp-up study was performed to optimize the LVAD settings for the patient. At 10 000 rpm, the LVAD generated a flow of 5.0 to 5.5 L/min. Over the next few days, the patient experienced frequent suction events, defined as movement of the interventricular septum toward the inflow cannula. These events required setting adjustments to 9800 rpm, followed by 9600 rpm. The number of suction events subsequently decreased; however, the flow rate was adversely affected and decreased to 3.6 to 4.2 L/min with the new settings. The patient’s underlying electric rhythm was atrial standstill versus a fine atrial fibrillation with a junctional escape rhythm at 60 bpm. It was observed that the patient had suction events after a premature ventricular contraction (PVC) or when he went into ventricular bigeminy. Echocardiography revealed that the septal movement was directed toward the inflow cannula after a PVC (Figure A and B) and was directed away from the inflow cannula after his normal junctional beat (Figure C and D and supplemental Movies 1 and 2). The patient had a preexisting single right ventricular (RV) lead implantable cardioverter defibrillator. Echocardiography revealed that RV paced beats moved the septum away from the inflow cannula during systole (Figure E and F and supplemental Movies 3 and 4). Furthermore, overdrive pacing at 70 bpm resulted in suppression of ventricular ectopy and resolution of the suction events, thereby allowing the LVAD to be readjusted to the original setting of 10 000 rpm, with subsequent improvement in flows. The improvement in septal motion was confirmed with M-mode echocardiography (Figure G and H). Although pacing has been reported to improve LVAD function in patients with older-generation LVADs and conduction abnormalities,1,2 to the best of our knowledge, this case represents the first report of RV pacing improving the function of an axial flow LVAD. Mechanisms explaining how RV pacing may improve LVAD function are not known. It may be that RV pacing and the subsequent dyssynchronous motion of the septum away from the inflow cannula during systole helps prevent the septum from obstructing LVAD filling—such techniques have been described for patients with refractory hypertrophic obstructive cardiomyopathy.3 Even though RV pacing causes left ventricular (LV) dyssynchrony—the negative effects of which would be less significant in the presence of a LVAD—it is possible that the initial right-sided activation of the septum may also enhance RV systolic function by improving RV synchrony. Improvement in RV function would thus increase circulation from the RV to the left ventricle, resulting in improved LV filling and a lower likelihood of a suction event. The possibility that RV pacing may improve RV function is certainly provocative, given that RV dysfunction is common after implantation of a LVAD.4 Finally, an additional mechanism may be that suppression of PVCs by overdrive pacing allows for more LV filling time compared with premature beats, thereby providing a larger LV end-diastolic volume and reducing the risk of a suction event. Given that a number of patients with LVADs have preexisting implantable cardioverter defibrillators with RV pacing capability, further studies of the role of RV pacing in improving axial flow LVAD function are warranted.

Correlation between plasma neurohormone levels and left ventricular functional and morphological improvement in LVAD patients

Objective: Certain neurohormones (e.g., brain natriuretic peptide (BNP), endothelin-1 (ET-1)) have demonstrated reliability as clinical markers of left ventricular (LV) function. The aim of this study was to examine the relationship between plasma levels of these neurohormones, LV function and histological evidence of morphological improvement in left ventricular assist device (LVAD) recipients to determine whether serial hormonal expression may be used to assess cardiac status in the LVAD setting. Methods: Plasma levels of BNP and ET-1 were measured in 19 end-stage congestive heart failure patients directly before and up to 18 weeks after implantation with various devices (DeBakeyVAD, Novacor, TCI HeartMate). Echocardiographic indices corresponding to the time-points of serial hormonal measurement were evaluated. Immunohistochemical collagen staining of LV tissue samples derived from LVAD patients at the time of device insertion and removal were then contrasted. Patients were grouped according to device employed and etiology (ischemic/dilated cardiomyopathy, ICMP/DCMP). Results: LVAD therapy significantly enhanced LV ejection fraction (EF%: 21% ± 3.8% to 37% ± 11.39%) and cardiac output (CO: 3.49 ± 1.3 to 7.3 ± 0.2 l/m) in all patients; other parameters were not appreciably altered. Absolute BNP and ET-1 plasma levels remained significantly lower in all patients after LVAD implantation (both: p < 0.001). The NOV group exhibited the most BNP reduction and EF% increase (p < 0.0004 and p < 0.038, respectively), whereas ET-1 was lower in the DVAD group (p < 0.06). In all categories, the ICMP group experienced more significant change when compared to those in the DCMP grouping. Collagen levels were sharply reduced in all patients (p < 0.0005); however, while those in the DVAD demonstrated the most evident change (p < 0.0036), there was little difference between the DCMP/ICMP groups (p < 0.012 vs p < 0.022). Both BNP and ET-1 manifested bi-phasic tendencies and an inverse proportionality to EF% measurements. Conclusions: Plasma BNP and ET-1 levels appear to correlate both with device-related LV functional and myocardial morphological improvement and may be of potential use as therapeutic indicators.