Estimation of the Severity of Aortic Insufficiency by HVAD Flow Waveform

Estimation of Left Ventricular Stroke Work for Rotary Left Ventricular Assist Devices

Continuous monitoring of left ventricular stroke work (LVSW) may improve the medical management of patients with rotary left ventricular assist devices (LVAD). However, implantable pressure-volume sensors are limited by measurement drift and hemocompatibility. Instead, estimator algorithms derived from rotary LVAD signals may be a suitable alternative. An LVSW estimator algorithm was developed and evaluated in a range of in vitro and ex vivo cardiovascular conditions during full assist (closed aortic valve [AoV]) and partial assist (opening AoV) mode. For full assist, the LVSW estimator algorithm was based on LVAD flow, speed, and pump pressure head, whereas for partial assist, the LVSW estimator combined the full assist algorithm with an estimate of AoV flow. During full assist, the LVSW estimator demonstrated a good fit in vitro and ex vivo (R 2 : 0.97 and 0.86, respectively) with errors of ± 0.07 J. However, LVSW estimator performance was reduced during partial assist, with in vitro : R 2 : 0.88 and an error of ± 0.16 J and ex vivo : R 2 : 0.48 with errors of ± 0.11 J. Further investigations are required to improve the LVSW estimate with partial assist; however, this study demonstrated promising results for a continuous estimate of LVSW for rotary LVADs.

Risk score for coronary heart disease (CHD-RISK) and hemodynamically significant aortic valve stenosis

BACKGROUND AND AIM

Multiple studies have investigated the association between coronary heart disease (CHD) risk factors and aortic valve stenosis (AS). However, limited studies have explored the relationship between CHD risk scores and AS. Whether incident risk scores for coronary heart disease (CHD-RISK) may be applied to predict AS remains unclear. We aim to investigate the association between AS and CHD-RISK.

METHODS AND RESULTS

We included 4791 participants (age 54.6 ± 5.0 yrs, 58.7% women, 81% were of European origin), and CHD-RISK was estimated in 1990-1992. The participants were then followed-up until December 31, 2013. The primary outcome was hemodynamic significant AS identified by Doppler echocardiography in 2011-2013. We used multivariate-logistic regression models to assess the associations between CHD-RISK and AS. During follow-up, 963 (20.1%) cases of AS were identified. Per-standard deviation (6%) increase in CHD-RISK was associated with OR 95% Cl [1.194, 95% CI 1.068 to 1.335, p = 0.002] risk of AS in the fully adjusted models. Results were similar when stratified by quintiles of CHD-RISK, using the lowest quintiles <0.94% of CHD-RISK as the reference, 0.94%-2.26%, 2.26%-4.83%, 4.83%-9.21%, and >9.21% were; 1.33 (95% CI, 0.99-1.78, p = 0.055), 1.64 (95% CI, 1.17-2.29, p = 0.004), 2.23 (95% CI, 1.49-3.32, p = <0.001), 2.66 (95% CI, 1.65-4.31, p = <0.001) respectively.

CONCLUSIONS

CHD-RISK was associated with AS. CHD-RISK and AS were high in females, age ≥55 yrs, current smokers, and BMI ≥ 30 kg/m². This investigation suggests CHD-RISK may be applied to forecast AS risk similar to CHD. Future studies are required to detect, manage, and establish better treatment strategies in these high-risk subgroups.

Impact of worsening of aortic insufficiency during HeartMate 3 LVAD support

Aortic insufficiency remains a difficult to treat and highly morbid condition even in the era of HeartMate 3 left ventricular assist devices (LVADs). The prognostic nature of the longitudinal progression of aortic insufficiency, however, remains unknown. We prospectively collected data on patients who received HeartMate 3 LVAD implantation, who had assessments of aortic insufficiency using a novel Doppler echocardiography obtained at outflow graft at three (baseline) and 6 months postimplant. Patients with moderate or greater aortic insufficiency at baseline were excluded. The risk of aortic insufficiency progression on 1-year death and readmission for heart failure was investigated. In total, 41 patients (median 51 years old and 29 males) were included. All patients had less than moderate aortic insufficiency at baseline. Of them, 22 patients had worsening aortic insufficiency for 3 months following baseline assessments, which was associated with a significantly higher risk of 1-year death or heart failure readmission rate (41% vs. 11%, P = .023) with a hazard ratio of 3.24 (95% confidence interval 1.02-18.5, P = .038) adjusted for device speed at baseline and destination therapy indication. In patients with HeartMate 3 LVADs, progressive aortic insufficiency may be associated with a higher risk of 1-year death or readmission for heart failure. Close monitoring of patients with baseline aortic insufficiency should be considered as a measure to risk-stratify those for future adverse events.

Implication of Hemodynamic Assessment during Durable Left Ventricular Assist Device Support

Durable left ventricular assist device therapy has improved survival in patients with advanced heart failure refractory to conventional medical therapy, although the readmission rates due to device-related comorbidities remain high. Left ventricular assist devices are designed to support a failing left ventricle through relief of congestion and improvement of cardiac output. However, many patients still have abnormal hemodynamics even though they may appear to be clinically stable. Furthermore, such abnormal hemodynamics are associated with an increased risk of future adverse events including recurrent heart failure, gastrointestinal bleeding, stroke, and pump thrombosis. Correction of residual hemodynamic derangements post-implantation may be a target in improving longitudinal clinical outcomes during left ventricular assist device support. Automatic and timely device speed adjustments considering a patients' hemodynamic status (i.e., with a smart pump) are potential improvements in forthcoming devices.