Right ventricular dysfunction following continuous flow left ventricular assist device placement in 51 patients: predicators and outcomes

Incidence and Diagnostic Challenges of Bowel Ischemia after Continuous-flow Left Ventricular Assist Device Therapy

Long-term continuous-flow left ventricular assist device (CFLVAD) therapy is limited by complications. Compared with stroke and renal dysfunction, post-CFLVAD bowel ischemia is poorly characterized. Adult patients who underwent first-time durable CFLVAD implantation at our institution between 2008 and 2018 were identified and screened for bowel ischemia using Current Procedural Terminology codes for abdominal surgical exploration and International Classification of Disease codes for intestinal vascular insufficiency. Patients who developed biopsy-proven bowel ischemia (cases) were matched to controls (1:1, nearest neighbor, caliper = 0.29) based on preoperative characteristics. Incidences of postoperative right heart failure and renal replacement therapy were compared using McNemar's test. One year survival was estimated using the Kaplan-Meier method. Overall, 711 patients underwent CFLVAD implantation. Nineteen (2.7%) developed bowel ischemia (cases) median 17 days postimplantation (IQR 8-71). The majority of cases were male (78.9%), Black (63.2%), received HeartMate II (57.9%), treated as destination therapy (78.9%), and had a history of hypertension (89.5%), chronic kidney disease (84.2%), hyperlipidemia (84.2%), smoking (78.9%), and atrial fibrillation (57.9%). Post-LVAD, case patients were more likely to develop moderate-severe right heart failure (89.5% vs. 68.4%, p = 0.005), require renal replacement therapy (21.1% vs. 0%, p < 0.001), and less likely to survive to discharge (52.6% vs. 89.5%, p = 0.02) compared with controls. Case subjects demonstrated worse 1 year survival. While less common than stroke and renal dysfunction, post-CFLVAD bowel ischemia is associated with high 1 year mortality. Multi-institutional registries should consider reporting abdominal complications such as bowel ischemia as an adverse event to further investigate these trends and identify predictors of this complication to reduce patient mortality.

Therapeutic augmentation of NO-sGC-cGMP signalling: lessons learned from pulmonary arterial hypertension and heart failure

The nitric oxide (NO)-guanylate cyclase (GC)-cyclic guanosine monophosphate (cGMP) pathway plays an important role in cardiovascular, pulmonary and renal function. Phosphodiesterase-5 inhibitors (PDE-5i) inhibit cGMP degradation, whereas both soluble guanylate cyclase (sGC) stimulators and sGC activators directly increase sGC. PDE-5i (e.g. sildenafil, tadalafil) and sGC stimulators (e.g. riociguat, vericiguat) have been extensively used in pulmonary artery hypertension (PAH) and heart failure (HF). PDE-5i have also been used in end-stage HF before and after left ventricular (LV) assist device (LVAD) implantation. Augmentation of NO-GC-cGMP signalling with PDE-5i causes selective pulmonary vasodilation, which is highly effective in PAH but may have controversial, potentially adverse effects in HF, including pre-LVAD implant due to device unmasking of PDE-5i-induced RV dysfunction. In contrast, retrospective analyses have demonstrated that PDE-5i have beneficial effects when initiated post LVAD implant due to the improved haemodynamics of the supported LV and the pleiotropic actions of these compounds. sGC stimulators, in turn, are effective both in PAH and in HF due to their balanced pulmonary and systemic vasodilation, and as such they are preferable to PDE-5i if the use of a pulmonary vasodilator is needed in HF patients, including those listed for LVAD implantation. Regarding the effectiveness of PDE-5i and sGC stimulators when initiated post LVAD implant, these two groups of compounds should be tested in a randomized control trial.

Right ventricle failure in patients treated with left ventricular assist device

This review article aim to highlight the right ventricular function peri left ventricular assist device implantation, and to assess the incidence, physiopathology, predictors, management and prognosis, of right ventricular failure post-implant.

Right ventricular failure following placement of a percutaneous left ventricular assist device

Right ventricular (RV) dysfunction following surgical implantation of a left ventricular assist device (LVAD) is a well-documented phenomenon, and it is associated with poor outcomes. We are reporting a 25-year-old male patient who presented to the hospital with flu-like symptoms, hypotension and acute hypoxic respiratory failure. The patient's Laboratory data was significant for elevated troponin, and his Chest X-ray showed acute pulmonary edema. Echocardiogram revealed reduced left ventricular (LV) ejection fraction and normal RV function. Coronary angiography was normal, and the cardiac index was 1.3 L/min/m². Impella 5.0 (Abiomed, MA) was placed through the left axillary artery graft and 4.5 L/min flow was achieved with an improvement in blood pressure. Thirty minutes later, he developed hypotension, the device flow dropped to 3.0 L/min, and right atrial pressure increased. The Pulmonary artery pulsatility index was consistent with RV failure. Possible causes of RV failure include unmasking of RV dysfunction with high LVAD flow and altered RV geometry due to ventricular septum shift. Impella RP (Abiomed, MA) was placed for RV support achieving a flow of 3.8 L/min with a significant improvement in impella LV flow, cardiac output and blood pressure (mean 90 mmHg). Ventricular support devices were weaned off on day 9. The patient was discharged on day 15. Conclusion: our case highlights the risk of RV failure following percutaneous LVAD placement. Early identification and appropriate mechanical support is imperative.

What Is the Heart? Anatomy, Function, Pathophysiology, and Misconceptions

Cardiac dynamics are traditionally linked to a left ventricle, right ventricle, and septum morphology, a topography that differs from the heart's five-century-old anatomic description of containing a helix and circumferential wrap architectural configuration. Torrent Guasp's helical ventricular myocardial band (HVMB) defines this anatomy and its structure, and explains why the heart's six dynamic actions of narrowing, shortening, lengthening, widening, twisting, and uncoiling happen. The described structural findings will raise questions about deductions guiding "accepted cardiac mechanics", and their functional aspects will challenge and overturn them. These suppositions include the LV, RV, and septum description, timing of mitral valve opening, isovolumic relaxation period, reasons for torsion/twisting, untwisting, reasons for longitudinal and circumferential strain, echocardiographic sub segmentation, resynchronization, RV function dynamics, diastolic dysfunction's cause, and unrecognized septum impairment. Torrent Guasp's revolutionary contributions may alter future understanding of the diagnosis and treatment of cardiac disease.

Concomitant mitral repair and continuous-flow left ventricular assist devices: Is it warranted?

BACKGROUND

Pre-existing mitral pathology is common in patients undergoing continuous-flow left ventricular assist device implantation. We sought to investigate whether concurrent mitral repair confers any advantage.

METHODS

From March 2004 to October 2014, 374 patients received a continuous-flow left ventricular assist device. Of these, a total of 115 patients with pre-existing mitral regurgitation (MR) greater than moderate were identified and included in the analysis. Outcomes were compared between patients with concurrent mitral repair (n = 52 [45.2%]; Group A) and without repair (n = 63 [54.8%]; Group B).

RESULTS

The mean age was 56.8 years and 25 (21.5%) were women. Patients in Group A were more likely to have undergone destination therapy (48.1% vs 11.1%; P < .001) and had a greater cardiopulmonary bypass time (125 vs 89 minutes; P < .001) than did patients in Group B. Longitudinal analysis using a generalized mixed-effects model demonstrated the odds of developing moderate or severe MR during device support were 86% lower for Group A patients (P < .001). Among those who were discharged alive, 9 (8.6%)-consisting of 1 (2.2%) in Group A and 8 (13.6%) in Group B (P = .039)-developed late right heart failure requiring a total of 13 readmissions (0.03 vs 0.15 readmissions per patient-year; P = .011). Multivariable competing risks regression revealed mitral repair to be a protective factor (hazard ratio, 0.16; 95% confidence interval, 0.03-0.94; P = .042) for late right heart failure occurrence.

CONCLUSIONS

Concurrent mitral repair appears to be efficacious in controlling MR after device implant. The fact that repaired patients developed late right heart failure less frequently than did patients without repair challenges the notion that concurrent mitral repair is unwarranted.

What Is the Optimal Setting for a Continuous-Flow Left Ventricular Assist Device in Severe Mitral Regurgitation?

Excessive left ventricular (LV) volume unloading can affect right ventricular (RV) function by causing a leftward shift of the interventricular septum in patients with mitral regurgitation (MR) receiving left ventricular assist device (LVAD) support. Optimal settings for the LVAD should be chosen to appropriately control the MR without causing RV dysfunction. In this study, we assessed the utility of our electrocardiogram-synchronized rotational speed (RS) modulation system along with a continuous-flow LVAD in a goat model of MR. We implanted EVAHEART devices after left thoracotomy in six adult goats weighing 66.4 ± 10.7 kg. Severe MR was induced through inflation of a temporary inferior vena cava filter placed within the mitral valve. We evaluated total flow (TF; the sum of aortic flow and pump flow [PF]), RV fractional area change (RVFAC) calculated by echocardiography, left atrial pressure (LAP), LV end-diastolic pressure (LVEDP), LV end-diastolic volume (LVEDV), and LV stroke work (LVSW) with a bypass rate (PF divided by TF) of 100% under four conditions: circuit-clamp, continuous mode, co-pulse mode (increased RS during systole), and counter-pulse mode (increased RS during diastole). TF tended to be higher in the counter-pulse mode. Moreover, RVFAC was significantly higher in the counter-pulse mode than in the co-pulse mode, whereas LAP was significantly lower in all driving modes than in the circuit-clamp condition. Furthermore, LVEDP, LVEDV, and LVSW were significantly lower in the counter-pulse mode than in the circuit-clamp condition. The counter-pulse mode of our RS modulation system used with a continuous-flow LVAD may offer favorable control of MR while minimizing RV dysfunction.

Impact of tricuspid valve surgery at the time of left ventricular assist device insertion on postoperative outcomes

Tricuspid regurgitation (TR) is common in patients with heart failure undergoing left ventricular assist device (LVAD) implantation. Whether the TR should be surgically managed at the time of LVAD surgery is controversial. We searched SCOPUS, Web of Science, Ovid EMBASE, and Ovid MEDLINE (through May 10, 2014) for randomized controlled trials and observational studies comparing postoperative outcomes in patients treated with LVAD with concomitant tricuspid valve surgery (TVS) compared with LVAD alone. Six observational studies including 3,249 patients compared outcomes following LVAD + TVS versus LVAD. Four studies were single-center and most did not adjust for potential confounders. Addition of TVS prolonged cardiopulmonary bypass times by an average of 31 minutes (three studies, 95% CI 20-42). There was no difference in need for right ventricular assist device (six studies, HR 1.42, 95% CI 0.54-3.76), acute renal failure (four studies, HR 1.07, 95% CI 0.55-2.10), or early mortality (six studies, HR 1.28, 95% CI 0.78-2.08) in patients treated with LVAD + TVS versus LVAD alone. TVS prolongs cardiopulmonary bypass times, but available data demonstrate no significant association with early postoperative outcomes. However, differences in baseline risk of patients treated with TVS versus not limit our ability to draw conclusions.

Hemodynamic transesophageal echocardiography after left ventricular assist device implantation

OBJECTIVE

The authors hypothesized that the clinical profile of patients undergoing hTEE after continuous flow left ventricular assist device (CF-LVAD) implant would be in patients with greater acuity, more blood product utilization, and longer length of ICU stay, and that hTEE would change clinical management.

DESIGN

Retrospective review.

SETTING

University hospital.

PARTICIPANTS

One hundred consecutive patients receiving a CF-LVAD.

INTERVENTIONS

Retrospective review using a standardized electronic form of a miniaturized disposable transesophageal echocardiography probe that documented not only physical findings but also changes in hemodynamic management (hTEE) in CF-LVAD patients.

MEASUREMENTS AND MAIN RESULTS

Of the 100 patients, 41 received an hTEE probe. The INTERMACS score, Leitz-Miller Score, and Kormos score indicated the hTEE group had a statistically significant greater risk of morbidity and mortality. Interoperatively, the hTEE group received more blood products and was more likely to have an open chest. Postoperatively, the hTEE group received more blood products, had a longer total length of stay, and had increased mortality. ICU length of stay, days on inotropes and days on mechanical ventilation were not statistically significant between the 2 groups. Information obtained from hTEE changed ICU management in 72% of studies.

CONCLUSION

Retrospective review of CF-LVAD patients revealed that postoperative hTEE is used in sicker CF-LVAD patients and frequently leads to changes in ICU clinical management.

Ventricular structure-function relations in health and disease: part II. Clinical considerations

Normal cardiac function of the left and right ventricles, together with the septum, is related to form/function interactions within the helical ventricular myocardial band. This knowledge is a prerequisite to understanding form/function interactions in diseases and for planning new treatments. Topics discussed include congestive heart failure in dilated hearts of ischaemic, valvar or nonischaemic origin as well as diastolic dysfunction. Similar thinking underlies novel treatments for dyssynchrony in pacing, together with focusing upon varying global left or right ventricular anatomy to correct mitral and tricuspid insufficiency caused by tethering of the leaflets. The septum is the lion of the right ventricle and insight is provided into offsetting septal damage during cardiac surgery, rebuilding its anatomical structure in post-tetralogy pulmonary insufficiency, as well as rectifying its dysfunction by decompression in patients with a left ventricular assist device.

TandemHeart Device as Rescue Therapy in the Management of Acute Heart Failure

<p><b>Background:</b> The TandemHeart device (THD) is a pump system that can be deployed percutaneously (PC) or via conventional surgical (CS) cannulation; it is capable of supporting one or both ventricles. It is a versatile system designed for use as a rescue device in acute heart failure and as a bridge to decision in moribund patients.</p><p><b>Methods:</b> Retrospective analysis was conducted on all patients who underwent a THD implant; either PC or CS; at our institution. Univariate analysis was done using Fisher's exact and Chi-square tests for categorical variables and Wilcoxon Rank Sum test for continuous ones.</p><p><b>Results:</b> 51 adult patients were identified: 10 PC and 41 CS. Mean age was 58.9 � 12.8 years, and 31% were female. In hospital mortality was 61%. Univariate predictors of death were prolonged support (74% versus 46%, <i>P</i> = .04) and higher lactic acid levels (5.3 � 4.9 versus 2.3 � 1.9 mmol/L, <i>P</i> = .012). The length of stay (LOS) for survivors was 59.8 � 30.0 days.</p><p><b>Conclusion:</b> Uni- or bi-ventricular unloading can be successfully achieved using the THD, either trans-thoracically or percutaneously, with an acceptable complication profile.</p>

Load Dependency of Right Ventricular Performance Is a Major Factor to be Considered in Decision Making Before Ventricular Assist Device Implantation

Background—

Left ventricular assist devices (LVADs) provide better outcome than biventricular devices, but it is a challenge to predict the impact of LV mechanical unloading on postoperative right ventricular (RV) function preoperatively. We assessed the load dependency in RV performance before and after LVAD implantation aiming to improve preoperative decision making.

Methods and Results—

Laboratory, echocardiography, and right heart catheterization data collected from 205 patients before LVAD implantation were tested for relationship with postoperative RV function. Comparing patients with different time-course of RV function after LVAD implantation, we found significant differences ( P <0.01) in preoperative RV end-diastolic short-/long-axis and long-axis/length-area ratios, tricuspid annulus peak systolic velocity, RV peak longitudinal global systolic strain rate, systolic pressure gradient between RV and right atrium (Δ P RV−RA ), tricuspid regurgitation velocity-time integral, and pulmonary arterial pressure between patients with and without postoperative RV failure. High predictive values for postoperative RV failure were found for end-diastolic short-/long-axis ratio ≥0.6, tricuspid annulus peak systolic velocity <8 cm/s, and peak systolic longitudinal strain rate <0.6/s in patients with maximum Δ P RV−RA <35 mm Hg. These parameters also seemed predictive for RV failure in patients with tricuspid regurgitation grade >2 and pulmonary arterial pressure <50 mm Hg. End-diastolic short-/long-axis ratio <0.6, tricuspid annulus peak systolic velocity ≥8 cm/s, and peak systolic longitudinal strain rate ≥0.6 in patients with maximum Δ P RV−RA ≥35 mm Hg showed high predictive values for postoperative freedom from RV failure. The RV load adaptation index seemed particularly predictive for RV function after LVAD implantation.

Conclusions—

RV geometry and velocity of contraction before LVAD implantation become more predictive for postoperative RV function and can improve decision making before VAD implantation if preoperative RV pressure load and tricuspid regurgitation are also considered.

Past and present of cardiocirculatory assist devices: a comprehensive critical review

During the last 20 years, the management of heart failure has significantly improved by means of new pharmacotherapies, more timely invasive treatments and device assisted therapies. Indeed, advances in mechanical support, namely with the development of more efficient left ventricular assist devices (LVADs), and the total artificial heart have reduced mortality and morbidity in patients awaiting transplantation, so much so, that LVADs are now approved of as a strategy for destination therapy. In this review, the authors describe in detail the current basic indications, functioning modalities, main limitations of surgical LAVDs, total artificial heart development, and percutaneous assist devices, trying to clarify this complex, but fascinating topic.