Pulsatility and flow patterns across macro- and microcirculatory arteries of continuous-flow left ventricular assist device patients

BACKGROUND

Reduced arterial pulsatility in continuous-flow left ventricular assist devices (CF-LVAD) patients has been implicated in clinical complications. Consequently, recent improvements in clinical outcomes have been attributed to the "artificial pulse" technology inherent to the HeartMate3 (HM3) LVAD. However, the effect of the "artificial pulse" on arterial flow, transmission of pulsatility into the microcirculation and its association with LVAD pump parameters is not known.

METHODS

The local flow oscillation (pulsatility index, PI) of common carotid arteries (CCAs), middle cerebral arteries (MCAs) and central retinal arteries (CRAs-representing the microcirculation) were quantified by 2D-aligned, angle-corrected Doppler ultrasound in 148 participants: healthy controls, n = 32; heart failure (HF), n = 43; HeartMate II (HMII), n = 32; HM3, n = 41.

RESULTS

In HM3 patients, 2D-Doppler PI in beats with "artificial pulse" and beats with "continuous-flow" was similar to that of HMII patients across the macro- and microcirculation. Additionally, peak systolic velocity did not differ between HM3 and HMII patients. Transmission of PI into the microcirculation was higher in both HM3 (during the beats with "artificial pulse") and in HMII patients compared with HF patients. LVAD pump speed was inversely associated with microvascular PI in HMII and HM3 (HMII, r2 = 0.51, p < 0.0001; HM3 "continuous-flow," r2 = 0.32, p = 0.0009; HM3 "artificial pulse," r2 = 0.23, p = 0.007), while LVAD pump PI was only associated with microcirculatory PI in HMII patients.

CONCLUSIONS

The "artificial pulse" of the HM3 is detectable in the macro- and microcirculation but without creating a significant alteration in PI compared with HMII patients. Increased transmission of pulsatility and the association between pump speed and PI in the microcirculation indicate that the future clinical care of HM3 patients may involve individualized pump settings according to the microcirculatory PI in specific end-organs.

Exercise ventilation inefficiency and dynamic tricuspid regurgitation in heart failure

Background

Exercise ventilation inefficiency, i.e. increase slope of the relationship of ventilation (VE) vs carbon dioxide (VCO2) slope is a key prognostic indicator in heart failure (HF). Many determinants have been identified primarily related to the left heart and impaired reflexogenic control of VE. In parallel, the severity of tricuspid regurgitation (TR) at rest is increasingly recognized as an important determinant of functional status and prognosis. It is undefined whether VE inefficiency may be related to the dynamic TR during exercise.

Purpose

We tested the role of dynamic TR and its correlates to exercise VE inefficiency by combining cardiopulmonary exercise test (CPET) with echocardiography.

Methods

We prospectively studied stable HF patients with both reduced and preserved left ventricular ejection fraction (LVEF). Patients with severe pulmonary disease and those who underwent valve replacement or cardiac surgery were excluded. Mitral and tricuspid regurgitation degree were adjudicated accordingly to ESC Guidelines criteria.

Demographics and clinical characteristics along with laboratory parameters including electrolytes, biomarkers of congestion (NT-proBNP), renal and liver function, were collected at the time of CPET. Dynamic TR was defined as worsening of TR grade from rest to stress detected by Doppler analysis. VE/VCO2 slope and peak oxygen consumption (pVO2) were compared between patients with dynamic TR (Group 1) vs non-dynamic TR (Group 2).

Results

Among 56 patients (66±13 years, 64% men, mean LVEF of 50±14%, 35% ischemic) 12% showed at least moderate mitral regurgitation and 16% patients had at least moderate TR at rest.

TR jet velocity at rest and at peak exercise were associated with VE/VCO2 slope (r=0.36 and r=0.3 respectively, p value &lt;0.05, Figure 1). A dynamic TR pattern (Group 1) appeared in 28 (50%) patients. No differences in clinical characteristics, laboratory parameters, LV ejection fraction, prevalence and degree of mitral regurgitation at rest and at peak were found between the two groups.

Group 1 compared to Group 2 exhibited a lower right ventricular fractional area change at peak exercise (45% [41–50] vs 52% [44–62] p=0.03), lower median pVO2 (13.3 [10.4–17.5] vs 16.3 [13.9–21.8], respectively (p=0.04)) and higher VE/VCO2 slope (40.3 [33.1–44] vs 34.1 [29.2–38.8], p=0.01; Figure 2A and B).

Conclusions

Patients with a dynamic TR pattern during CPET imaging exhibit a worse VE efficiency that correlates with TR extent. These data prospect, for the first time, an interaction between dynamic TR and ventilatory pattern during exercise in HF whose relevance may translate in targeting the right heart appropriately.

Funding Acknowledgement

Type of funding sources: None.

Sacubitril/Valsartan in heart failure with reduced ejection fraction: clinical and echocardiographic insights from a real world population

Background

Following the PARADIGM trial, some studies have identified cardiac remodeling as major background for hard end point benefits of Sacubitril/Valsartan (S/V), but few adopted a well described definition in the literature.

Purpose

We aimed at a comprehensive evaluation of the effects of S/V on echo-derived measures of cardiac remodeling along with clinical and laboratory data over a medium-term follow-up pointing to a real-world HFrEF population.

Methods

This is a prospective observational study of HFrEF patients on optimal medical therapy (OMT) initiated with S/V at Heart Failure Clinic of our institute (January 2017-January 2020). In 62 HFrEF, echocardiographic, laboratory and clinical data were collected at baseline and over 10 (Q1-Q3 8–13) months after S/V initiation. Mean age was 68±12 years, 79% men. Left ventricular reverse remodeling (LVRR) was defined as: 1) an absolute increase in LVEF ≥10 points or a LVEF ≥50% at follow-up and 2) a relative decrease in indexed left ventricular end-diastolic diameter of at least 10% or an indexed left ventricular end-diastolic diameter ≤33 mm/m2.

Results

Compared to baseline, S/V promoted a significant improvement of LV ejection fraction (LVEF, from 30% to 37%; p&lt;0,0001) with an absolute median increase in LVEF of 8 points. Parallel significant reductions in left ventricular and atrial volumes, lower mitral regurgitation degree and a better diastolic dysfunction along with clinical improvement (NYHA class and NT-proBNP values) were observed at follow up. sPAP (systolic Pulmonary Arterial Pressure) was significantly decreased at follow-up evaluation (37 mmHg vs 31 mmHg p=0,005) (Table 1). Overall, LVRR as defined above was observed in 30% of patients. Younger age (64 vs 74 years, p=0,007), a shorter duration of the disease (7 vs 23 months, p=0,009), and non ischaemic etiology (79% vs 33% p=0,003), along with a smaller baseline LAESVi (Left Atrial End Systolic Volume, 41 vs 48 ml/m2 p=0,012) were more common in patients with LVRR. sPAP and Right Ventricular (RV) function estimated by tricuspid annular plane systolic excursion (TAPSE) were significantly better in LVRR patients along with TAPSE/sPAP ratio (Table 2).

Conclusions

Our data point to a remarkable medium-term reverse remodeling effect by S/V in HFrEF. Findings reinforce the concept that the main benefits of S/V on hard end-points are mediated by its cardiac-related effects. Both a left and right reverse remodeling occur in HFrEF patients who start S/V in the most adaptable phase of the disease supporting an early administration.

Funding Acknowledgement

Type of funding sources: None.

Cerebral vasoreactivity in HeartMate 3 patients

BACKGROUND

While rates of stroke have declined with the HeartMate3 (HM3) continuous- flow (CF) left ventricular assist device (LVAD), the impact of non-pulsatile flow and artificial pulse physiology on cerebrovascular function is not known. We hypothesized that improved hemodynamics and artificial pulse physiology of HM3 patients would augment cerebrovascular metabolic reactivity (CVR) compared with HeartMate II (HMII) CF-LVAD and heart failure (HF) patients.

METHODS

Mean, peak systolic and diastolic flow velocities (MFV, PSV, MinFV, respectively) and cerebral pulsatility index were determined in the middle cerebral artery (MCA) before and after a 30 sec breath-hold challenge in 90 participants: 24 healthy controls; 30 HF, 15 HMII, and 21 HM3 patients.

RESULTS

In HM3 patients, breath-holding increased MFV (Δ8 ± 10 cm/sec, p < .0001 vs baseline) to levels similar to HF patients (Δ9 ± 8 cm/sec, p > .05), higher than HMII patients (Δ2 ± 8 cm/sec, p < .01) but lower than healthy controls (Δ13 ± 7 cm/sec, p < .05). CF-LVAD altered the proportion of systolic and diastolic flow responses as reflected by a differential cerebral pulsatility index (p = .03). Baseline MFV was not related to CVR (r² = 0.0008, p = .81). However, CF-LVAD pump speed was strongly inversely associated with CVR in HM II (r² = 0.51, p = .003) but not HM3 patients (r² = 0.01, p = .65).

CONCLUSIONS

Compared with HMII, HM3 patients have a significantly improved CVR. However, CVR remains lower in HM3 and HF patients than in healthy controls, therefore suggesting that changes in cerebral hemodynamics are not reversed by CF-LVAD therapy. Further research on the mechanisms and the long-term impact of altered cerebral hemodynamics in this unique patient population are warranted.

Clinical Impact of Hematoma Expansion in Left Ventricular Assist Device Patients

BACKGROUND

Hematoma expansion (HE) is associated with poor outcome in patients with intracerebral hemorrhage (ICH), but the impact on patients with an left ventricular assist device (LVAD) is unknown. We aimed to define the occurrence of HE in the LVAD population and to determine the association between HE and mortality.

METHODS

We performed a retrospective cohort study of LVAD patients and intentionally matched anticoagulated controls without LVAD admitted to Columbia University Irving Medical Center with ICH between 2008 and 2019. We compared HE occurrence between patients with an LVAD and those without an LVAD using regression modeling, adjusting for factors known to influence HE. We evaluated pump thrombosis following anticoagulation reversal. We examined the association between HE and hospital mortality using Poisson regression modeling adjusting for factors associated with poor outcome.

RESULTS

Among 605 patients with an LVAD, we identified 28 patients with ICH meeting the study's inclusion criteria. Our LVAD ICH cohort was predominantly male (71%), with a mean age of 56 ± 10 years. The median baseline hematoma size was 20.1 mL³ (interquartile range [IQR], 8.6-46.9 mL³), and the median ICH score was 1 (IQR, 1-2). There was no significant difference in occurrence of HE in LVAD patients and matched non-LVAD patients (adjusted odds ratio [OR], 1.3; 95% confidence interval [CI], 0.4-4.2). There was an association between HE and in-hospital mortality in LVAD patients (adjusted OR, 4.8; 95% CI, 1.4-6.2).

CONCLUSIONS

HE occurrence appears to be similar in LVAD and non-LVAD patients. HE has a significant impact on LVAD ICH mortality, underscoring the importance of adequate coagulopathy reversal and blood pressure management in these patients.