Derivation of Stroke Volume from Pulmonary Artery Pressures

INTRODUCTION

Intermittent cardiac output (CO) studies using thermodilution are considered the gold standard. We have developed a stroke volume (SV) calculator from pulmonary pulse pressure (PP) to allow continuous monitoring of SV and CO from PP.

METHODS

Hemodynamic data on 169 patients following orthotopic heart transplantation were used to compare our calculator-derived SV (and SV index, or SVi) against thermodilution-derived SV on admission into intensive care unit immediately following heart transplantation (T0) and 6 h after admission (T6).

RESULTS

The calculated SV correlated with thermodilution-derived SV T0 (r = 0.920, p < 0.001, coefficient of 0.539 and the constant of 2.06). The median calculator SV, adjusted for coefficient and constant, was 48.4 ml (37.7, 60.7), comparable to the median thermodilution-derived SV 47.9 ml (37.5, 61.0), p = 0.737 with acceptable agreement on Bland-Altman plots. The thermodilution-derived SVi was 28.1 ml (19.7, 38.7) and adjusted calculator-derived SVi 28.9 ml (19.7, 39.9), p = 0.781. At T6, median thermodilution-derived SVi was 27.7 ml (19.5, 35.9) compared to the calculator-derived SVi median of 26.1 ml (17.7, 37.7), p = 0.203.

CONCLUSIONS

Changes in PP can be used to track changes in SV using this calculator. Changes in PP may be used to assess response to treatment in the early post-operative period.

The management of heart failure cardiogenic shock: an international RAND appropriateness panel

BACKGROUND

Observational data suggest that the subset of patients with heart failure related CS (HF-CS) now predominate critical care admissions for CS. There are no dedicated HF-CS randomised control trials completed to date which reliably inform clinical practice or clinical guidelines. We sought to identify aspects of HF-CS care where both consensus and uncertainty may exist to guide clinical practice and future clinical trial design, with a specific focus on HF-CS due to acute decompensated chronic HF.

METHODS

A 16-person multi-disciplinary panel comprising of international experts was assembled. A modified RAND/University of California, Los Angeles, appropriateness methodology was used. A survey comprising of 34 statements was completed. Participants anonymously rated the appropriateness of each statement on a scale of 1 to 9 (1-3 as inappropriate, 4-6 as uncertain and as 7-9 appropriate).

RESULTS

Of the 34 statements, 20 were rated as appropriate and 14 were rated as inappropriate. Uncertainty existed across all three domains: the initial assessment and management of HF-CS; escalation to temporary Mechanical Circulatory Support (tMCS); and weaning from tMCS in HF-CS. Significant disagreement between experts (deemed present when the disagreement index exceeded 1) was only identified when deliberating the utility of thoracic ultrasound in the immediate management of HF-CS.

CONCLUSION

This study has highlighted several areas of practice where large-scale prospective registries and clinical trials in the HF-CS population are urgently needed to reliably inform clinical practice and the synthesis of future societal HF-CS guidelines.

Hemodynamic management of cardiogenic shock in the intensive care unit

Hemodynamic derangements are defining features of cardiogenic shock. Randomized clinical trials have examined the efficacy of various therapeutic interventions, from percutaneous coronary intervention to inotropes and mechanical circulatory support (MCS). However, hemodynamic management in cardiogenic shock has not been well-studied. This State-of-the-Art review will provide a framework for hemodynamic management in cardiogenic shock, including a description of the 4 therapeutic phases from initial 'Rescue' to 'Optimization', 'Stabilization' and 'de-Escalation or Exit therapy' (R-O-S-E), phenotyping and phenotype-guided tailoring of pharmacological and MCS support, to achieve hemodynamic and therapeutic goals. Finally, the premises that form the basis for clinical management and the hypotheses for randomized controlled trials will be discussed, with a view to the future direction of cardiogenic shock.

Left-Ventricular Unloading With Impella During Refractory Cardiac Arrest Treated With Extracorporeal Cardiopulmonary Resuscitation: A Systematic Review and Meta-Analysis

OBJECTIVES

Extracorporeal cardiopulmonary resuscitation (ECPR) is the implementation of venoarterial extracorporeal membrane oxygenation (VA-ECMO) during refractory cardiac arrest. The role of left-ventricular (LV) unloading with Impella in addition to VA-ECMO ("ECMELLA") remains unclear during ECPR. This is the first systematic review and meta-analysis to characterize patients with ECPR receiving LV unloading and to compare in-hospital mortality between ECMELLA and VA-ECMO during ECPR.

DATA SOURCES

Medline, Cochrane Central Register of Controlled Trials, Embase, and abstract websites of the three largest cardiology societies (American Heart Association, American College of Cardiology, and European Society of Cardiology).

STUDY SELECTION

Observational studies with adult patients with refractory cardiac arrest receiving ECPR with ECMELLA or VA-ECMO until July 2023 according to the Preferred Reported Items for Systematic Reviews and Meta-Analysis checklist.

DATA EXTRACTION

Patient and treatment characteristics and in-hospital mortality from 13 study records at 32 hospitals with a total of 1014 ECPR patients. Odds ratios (ORs) and 95% CI were computed with the Mantel-Haenszel test using a random-effects model.

DATA SYNTHESIS

Seven hundred sixty-two patients (75.1%) received VA-ECMO and 252 (24.9%) ECMELLA. Compared with VA-ECMO, the ECMELLA group was comprised of more patients with initial shockable electrocardiogram rhythms (58.6% vs. 49.3%), acute myocardial infarctions (79.7% vs. 51.5%), and percutaneous coronary interventions (79.0% vs. 47.5%). VA-ECMO alone was more frequently used in pulmonary embolism (9.5% vs. 0.7%). Age, rate of out-of-hospital cardiac arrest, and low-flow times were similar between both groups. ECMELLA support was associated with reduced odds of mortality (OR, 0.53 [95% CI, 0.30-0.91]) and higher odds of good neurologic outcome (OR, 2.22 [95% CI, 1.17-4.22]) compared with VA-ECMO support alone. ECMELLA therapy was associated with numerically increased but not significantly higher complication rates. Primary results remained robust in multiple sensitivity analyses.

CONCLUSIONS

ECMELLA support was predominantly used in patients with acute myocardial infarction and VA-ECMO for pulmonary embolism. ECMELLA support during ECPR might be associated with improved survival and neurologic outcome despite higher complication rates. However, indications and frequency of ECMELLA support varied strongly between institutions. Further scientific evidence is urgently required to elaborate standardized guidelines for the use of LV unloading during ECPR.

Consensus statements from the International Society for Heart and Lung Transplantation consensus conference: Heart failure-related cardiogenic shock

The last decade has brought tremendous interest in the problem of cardiogenic shock. However, the mortality rate of this syndrome approaches 50%, and other than prompt myocardial revascularization, there have been no treatments proven to improve the survival of these patients. The bulk of studies have been in patients with acute myocardial infarction, and there is little evidence to guide the clinician in those patients with heart failure cardiogenic shock (HF-CS). An International Society for Heart and Lung Transplant consensus conference was organized to better define, diagnose, and manage HF-CS. There were 54 participants (advanced heart failure and interventional cardiologists, cardiothoracic surgeons, critical care cardiologists, intensivists, pharmacists, and allied health professionals) with vast clinical and published experience in CS, representing 42 centers worldwide. This consensus report summarizes the results of a premeeting survey answered by participants and the breakout sessions where predefined clinical issues were discussed to achieve consensus in the absence of robust data. Key issues discussed include systems for CS management, including the "hub-and-spoke" model vs a tier-based network, minimum levels of data to communicate when considering transfer, disciplines that should be involved in a "shock team," goals for mechanical circulatory support device selection, and optimal flow on such devices. Overall, the document provides expert consensus on some important issues facing practitioners managing HF-CS. It is hoped that this will clarify areas where consensus has been reached and stimulate future research and registries to provide insight regarding other crucial knowledge gaps.

A novel 'shunt fraction' method to derive native cardiac output during liberation from central VA ECMO

The Fick principle is an established method to quantify intracardiac shunts. The Fick principle has also found utility in the practice of extracorporeal membrane oxygenation (ECMO). This report describes a novel 'shunt fraction' method to calculate intrinsic cardiac output in central (right atrial-to-aorta) ECMO. The physiological basis of this 'shunt fraction' method is described, followed by the case presentation that details the clinical application of this method of quantifying intrinsic cardiac output to guide weaning and liberation from central VA ECMO.

The History of Extracorporeal Membrane Oxygenation and the Development of Extracorporeal Membrane Oxygenation Anticoagulation

Extracorporeal membrane oxygenation (ECMO) was first started for humans in early 1970s by Robert Bartlett. Since its inception, there have been numerous challenges with extracorporeal circulation, such as coagulation and platelet activation, followed by consumption of coagulation factors and platelets, and biocompatibility of tubing, pump, and oxygenator. Unfractionated heparin (heparin hereafter) has historically been the defacto anticoagulant until recently. Also, coagulation monitoring was mainly based on bedside activated clotting time and activated partial thromboplastin time. In the past 50 years, the technology of ECMO has advanced tremendously, and thus, the survival rate has improved significantly. The indication for ECMO has also expanded. Among these are clinical conditions such as postcardiopulmonary bypass, sepsis, ECMO cardiopulmonary resuscitation, and even severe coronavirus disease 2019 (COVID-19). Not surprisingly, the number of ECMO cases has increased according to the Extracorporeal Life Support Organization Registry and prolonged ECMO support has become more prevalent. It is not uncommon for patients with COVID-19 to be on ECMO support for more than 1 year until recovery or lung transplant. With that being said, complications of bleeding, thrombosis, clot formation in the circuit, and intravascular hemolysis still remain and continue to be major challenges. Here, several clinical ECMO experts, including the "Father of ECMO"-Dr. Robert Bartlett, describe the history and advances of ECMO.

Pulmonary artery wave intensity analysis in pulmonary hypertension associated with heart failure and reduced left ventricular ejection fraction

Wave intensity analysis (WIA) uses simultaneous changes in pressure and flow velocity to determine wave energy, type, and timing of traveling waves in the circulation. In this study, we characterized wave propagation in the pulmonary artery in patients with pulmonary hypertension associated with left-sided heart disease (PHLHD) and the effects of dobutamine. During right heart catheterization, pressure and velocity data were acquired using a dual-tipped pressure and Doppler flow sensor wire (Combowire; Phillips Volcano), and processed offline using customized Matlab software (MathWorks). Patients with low cardiac output underwent dobutamine challenge. Twenty patients with PHLHD (all heart failure with reduced left ventricular ejection fraction) were studied. Right ventricular systole produced a forward compression wave (FCW), followed by a forward decompression wave (FDW) during diastole. Wave reflection manifesting as backward compression wave (BCW) following the FCW was observed in 14 patients. Compared to patients without BCW, patients with BCW had higher mean pulmonary artery pressure (28.7 ±  6.12 vs. 38.6 ± 6.5 mmHg, p = 0.005), and lower pulmonary arterial capacitance (PAC: 2.88 ± 1.75 vs. 1.73 ± 1.16, p = 0.002). Pulmonary vascular resistance was comparable. Mean pulmonary artery pressure of 34.5 mmHg (area under the curve [AUC]: 0.881) and PAC of 2.29 mL/mmHg (AUC: 0.833) predicted BCW. The magnitude of the FCW increased with dobutamine (n = 11) and correlated with pulmonary artery wedge pressure. Wave reflection in PHLHD is more likely at higher pulmonary artery pressures and lower PAC and the magnitude of reflected waves correlated with pulmonary artery wedge pressure. Dobutamine increased FCW but did not affect wave reflection.

A Systematic Review and Physiology of Pulmonary Artery Pulsatility Index in Left Ventricular Assist Device Therapy

BACKGROUND

Right heart failure is a major complication following left ventricular assist device (LVAD) implantation. Pulmonary artery pulsatility index (PAPi) has been evaluated as a haemodynamic marker for right heart failure, but PAPi is dependent on pulmonary vascular resistance. We conducted a systematic review to assess the relationship between PAPi and right heart failure and death in patients undergoing LVAD implantation; and examined the relationship between PAPi cut-off and pulmonary vascular resistance.

METHODS

We searched PubMed, EMBASE, CENTRAL and manually screened retrieved references to identify all clinical studies reporting PAPi in adult patients with a durable LVAD. Eligibility criteria were prespecified and two reviewers independently screened and extracted data; the Newcastle-Ottawa Scale was used to assess quality of non-randomized studies. This study was prospectively registered on PROSPERO (CRD42021259009).

RESULTS

From 283 unique records, we identified 16 studies reporting haemodynamic assessment in 20,634 adult patients with an implanted durable LVAD. Only 2 studies reported on mortality and in both, a lower PAPi was significantly associated with death. Fifteen studies reported right heart failure data and in ten studies a lower PAPi was significantly associated with right heart failure. Six studies reported on PAPi cut-offs ranging from 0.88 to 3.3; and the cut-offs were directly related to pulmonary vascular resistance (r = 0.6613, p = 0.019).

CONCLUSIONS

Lower PAPi was associated with right heart failure and death following LVAD implantation, but a single PAPi cut-off cannot be defined, as it is dependent on pulmonary vascular resistance.

Phenotyping and Hemodynamic Assessment in Cardiogenic Shock: From Physiology to Clinical Application

There is growing interest in invasive hemodynamic assessment in cardiogenic shock, primarily due to the widespread adoption of mechanical circulatory support (MCS). Invasive hemodynamic assessment is central to two aspects of cardiogenic shock management: (1) the phenotyping of cardiogenic shock, and (2) the assessment of response to therapy. Phenotyping of cardiogenic shock serves to guide timely therapeutic intervention, and the assessment of hemodynamic response to therapy directs the escalation or de-escalation of therapy, including MCS. This review aims to discuss these two aspects of hemodynamic assessment in cardiogenic shock. Firstly, the physiologic underpinnings of a phenotyping schema, and the implication of the cardiogenic shock phenotype on the MCS strategy in cardiogenic shock will be discussed. Secondly, the concept of cardiac power output and 'effective' oxygen delivery will be discussed in relation to hemodynamic response to therapy in cardiogenic shock.

How does protocolization improve outcomes in cardiogenic shock due to end-stage heart failure?

BACKGROUND

Protocolized team-based care has been shown to improve outcomes in cardiogenic shock (CS) in patients with end-stage heart failure (ESHF). This study tested the hypothesis that protocolized care improves survival by reducing multi-organ dysfunction prior to orthotopic heart transplantation (OHT) or durable left ventricular assist device (LVAD).

METHODS

We developed a protocolized Recognize/rescue-Optimization-Stabilization-Exit/de-Escalation (ROSE) framework for CS due to ESHF. Six-month survival pre-ROSE (2014-2018) and post-ROSE (2018-2021) were compared. The Sequential Organ Failure Assessment (SOFA) score was calculated as a measure of multi-organ dysfunction pre-MCS and pre-"Exit" therapy (OHT, LVAD or recovery).

RESULTS

101 consecutive patients with CS due to ESHF who were deteriorating on inotropes (INTERMACS 1 or 2) were included (63 in Pre-ROSE and 38 in Post-ROSE). The proportions of patients who died on support (26 (41%) vs 11 (29%), p = 0.213) or bridged to "Exit" therapy were comparable between Pre- and Post-ROSE: OHT (28 (44%) vs 21 (55%), p = 0.292); durable LVAD (8 (13%) vs 5 (13%), p = 0.947); or recovery (1 (2%) vs 1 (3%), p = 0.715). SOFA score prior to "Exit" therapy was higher Pre-ROSE compared to Post-ROSE (4 (2-7) vs 2 (1-5), p = 0.012). Six-month survival from initial MCS (71% vs 41%, p = 0.004) and in patients who underwent "Exit" therapy (100% vs 71%, p = 0.001) were higher Post-ROSE vs Pre-ROSE, respectively. Higher pre-"Exit" SOFA score was associated with 6-month survival. None of the patients with Pre-"Exit" SOFA score ≥ 9 survived at 6 months.

CONCLUSION

Protocolization of CS care in ESHF improved six-month survival by improving multi-organ dysfunction (SOFA score) prior to OHT and LVAD implant.

Proportional pulmonary pulse pressure: A new index to assess response to veno-arterial extracorporeal membrane oxygenation

BACKGROUND

Based on theoretical physiology, the ratio of pulmonary artery pulse pressure to mean pulmonary pressure (PP-MPAP), termed proportional pulmonary pulse pressure, provides a measure of coupling between the right ventricle and the pulmonary circulation. This study tested the hypothesis that lower PP-MPAP ratio was associated with left ventricular (LV) distension in patients with cardiogenic shock who underwent extracorporeal life support (ECLS).

METHODS

This is a retrospective observational single-centre study of 22 patients with cardiogenic shock who underwent ECLS as the primary support modality without and with LV distension and Impella unloading. The relationship between post-support PP-MPAP and 12-hour lactate clearance was also assessed.

RESULTS

Of the 22 patients: 10 patients underwent additional Impella unloading due to LV distension (Group 1) and 12 patients on ECLS only without LV distension (Group 2). As predicted by the theoretical model, PP-MPAP on ECLS dropped in Group 1 (pre-Impella) from 0.473 ± 0.067 to 0.372 ± 0.087, p < 0.001; but increased in Group 2 patients without LV distension (0.518 ± 0.070 to 0.549 ± 0.072, p = 0.002). Impella support in Group 1 increased PP-MPAP (0.372 ± 0.087 to 0.615 ± 0.094, p < 0.001). On multiple regression analysis, post-support PP-MPAP was significantly associated with 12-hour lactate clearance.

CONCLUSION

Changes in PP-MPAP is associated hemodynamic response to ECLS and 12-hour lactate clearance. This simple parameter may guide therapeutic optimization in cardiogenic shock and ECLS.

Near-miss Thoracic Spine Solitary Plasmacytoma with Neurological Deficit during Pregnancy: A Case Report

Solitary plasmacytoma (SPC) account for only 5% of plasma cell neoplasms, and the literature hardly reports spinal SPC with a neurological deficit. Furthermore, spinal surgical intervention during pregnancy is rarely encountered and often requires multidisciplinary collaboration and management. The objective of this case report is to highlight this near-miss diagnosis and spinal surgical intervention during pregnancy. A 31-year-old woman with 24 weeks gestation presented with sudden paralysis and incontinence, with an underlying history of chronic backpain over a two-month period. Initially, she was treated for musculoskeletal back pain by obstetric colleagues during an antenatal visit, and no radiograph was performed. A non-contrasted spinal MRI was eventually requested when she started to show bilateral lower limb weakness, numbness and incontinence. The MRI highlighted thoracic vertebrae T11 vertebra plana with kyphotic deformity and a paraspinal soft tissue mass compressing the spinal cord causing spinal cord oedema. Our initial working diagnosis was spinal tuberculosis (TB), considering TB is highly endemic in Malaysia. However, TB workup was negative, and we proceeded with spinal surgery and transpedicular biopsy. Neurology improved significantly after surgery. Eventually, serum protein electrophoresis reported plasma dyscrasia, and HPE confirmed plasmacytoma. The patient was referred to a haematologist for steroidal and chemotherapy treatment.

Living with a left ventricular assist device: Capturing recipients experiences using group concept mapping software

Background

Left ventricular assist device (LVAD) implantation significantly impacts on a recipient’s symptoms and quality of life. Capturing their experiences and post implant journey is an important part of clinical practice, research and device design evolution. Patient reported outcome measures (PROMs) are a useful tool for capturing that experience. However, patient reported outcome measures need to reflect recipients’ experiences. Discussions with a patient partner group found that none of the frequently used cardiology PROMs captured their unique experiences.

Aims

To capture the experiences and important issues for LVAD recipients. Develop a conceptual map of domains and items that should be reflected in patient reported outcomes.

Methods

Group concept mapping (GCM) web-based software was used to remotely capture and structure recipients’ experiences across a wide geographical area. GCM is a semi-quantitative mixed method consisting of 3 stages: item generation, item sorting and rating (importance, relevance and frequency). Patient partners were involved in all aspects of the study design and development.

Results

18 LVAD recipients consented to take part. 101 statements were generated and multi-dimensional scaling, and hierarchical cluster analysis identified 9 clusters. Cluster themes included: Activities, Partner/family support, Travel, Mental wellbeing, Equipment and clothing, Physical and cognitive limitations, LVAD Restrictions, LVAD Challenges and positive impact of the LVAD (LVAD Positives). LVAD Positives were scored highest across all the rating variables, e.g., frequency (2.85), relevance (2.44) and importance (2.21). Other domains rated high for importance included physical and cognitive limitations (2.19), LVAD restrictions (2.11), Partner/family support (2.02), and Equipment and clothing (2.01).

Conclusion

Online GCM software facilitated the inclusion of geographically dispersed recipients and provided useful insights into the experiences of LVAD recipients. The conceptual framework identifies important domains and items that should be prioritised and included in patient reported outcomes in future research, LVAD design evolution, and clinical practice.

Prognostic value of right atrial pressure-corrected cardiac power index in cardiogenic shock

AIM

The pulmonary artery catheter (PAC)-derived cardiac power index (CPI) has been found of prognostic value in cardiogenic shock (CS) patients. The original CPI equation included the right atrial pressure (RAP), accounting for heart filling pressure as a determinant of systolic myocardial work, but this term was subsequently omitted. We hypothesized that the original CPI formula (CPI_RAP ) is superior to current CPI for risk stratification in CS.

METHODS AND RESULTS

A single-centre cohort of 80 consecutive Society for Cardiovascular Angiography and Interventions (SCAI) B-D CS patients with available PAC records was included. Overall in-hospital mortality was 21.3%. Results showed CPI_RAP to be the strongest haemodynamic predictor of in-hospital death (p_adj  = 0.038), outperforming CPI [area under the receiver operating characteristic (ROC) curves: 0.726 and 0.673, P-for-difference = 0.025]. When the population was stratified according to the identified CPI_RAP (0.28 W/m² ) and accepted CPI (0.32 W/m² ) thresholds, the cohort with discordant indexes (low CPI_RAP and high CPI) comprised a group of 13 patients featuring a congested phenotype with frequent right ventricle or biventricular involvement. In this group, in-hospital mortality was high (30.8%) similar to those with concordant low CPI and CPI_RAP .

CONCLUSION

Incorporating RAP in CPI calculation (CPI_RAP ) improves the prognostic yield in patients with CS SCAI B-D. A cut-off of 0.28 W/m² identifies patients at higher risk of in-hospital mortality. The improved prognostic value of CPI_RAP may derive from identification of patients with more intravascular congestion who may experience substantial in-hospital mortality, uncaptured by the commonly used CPI equation.

Cardiac power output index to define hemodynamic response to Impella support in cardiogenic shock

BACKGROUND

Early assessment of response to Impella in cardiogenic shock may guide escalation of mechanical circulatory support. Therapeutic goal and response to Impella have not previously been defined. This study tested the hypothesis that targeting 3-h post- Impella cardiac power output index (CPOi)-"hemodynamic response"-in cardiogenic shock is associated with 12-h lactate clearance.

METHODS

Single-center study of 37 consecutive patients who underwent left-sided Impella support for cardiogenic shock due to either acute myocardial infarction or decompensated heart failure. Patients who achieved 3-h post-Impella CPOi ⩾ 0.30 W/m² were defined as Impella "hemodynamic responder."

RESULTS

Twelve of the thirty-seven patients achieved 3-h post-impella CPOi  ⩾ 0.30 W/m² ("hemodynamic responders"). Post-Impella CPOi correlated with 12-h lactate (r = -0.779, p < 0.001) and lactate clearance (r = 0.747, p < 0.001). "Hemodynamic responders" had lower 12-h lactate level and greater 12-h lactate clearance (52 (44-58) vs 17 (14-26)%, p < 0.001). Higher pre-Impella norepinephrine dose (-0.341, p = 0.003) and baseline lactate (-0.009, p = 0.003) were independently associated with lower 3-h post-Impella CPOi. Eighteen patients died within 30 days (2/12 "hemodynamic responders" compared to 16/25 "non-responders," p < 0.001).

CONCLUSION

Patients who achieved early 3-h post-Impella CPOi of ⩾0.30 W/m² have greater lactate clearance and better short-term survival. Early post-Impella CPOi of 0.30 W/m² may be used as a therapeutic goal and define favorable response to Impella in cardiogenic shock.

Real-world evidence in a national health service: results of the UK CardioMEMS HF System Post-Market Study

Aims

The CardioMEMS HF System Post‐Market Study (COAST) was designed to evaluate the safety, effectiveness, and feasibility of haemodynamic‐guided heart failure (HF) management using a small sensor implanted in the pulmonary artery of New York Heart Association (NYHA) Class III HF patients in the UK, Europe, and Australia.

Methods and results

COAST is a prospective, international, multicentre, open‐label clinical study (NCT02954341). The primary clinical endpoint compares annualized HF hospitalization rates after 1 year of haemodynamic‐guided management vs. the year prior to sensor implantation in patients with NYHA Class III symptoms and a previous HF hospitalization. The primary safety endpoints assess freedom from device/system‐related complications and pressure sensor failure after 2 years. Results from the first 100 patients implanted at 14 out of the 15 participating centres in the UK are reported here. At baseline, all patients were in NYHA Class III, 70% were male, mean age was 69 ± 12 years, and 39% had an aetiology of ischaemic cardiomyopathy. The annualized HF hospitalization rate after 12 months was 82% lower [95% confidence interval 72–88%] than the previous 12 months (0.27 vs. 1.52 events/patient‐year, respectively, P < 0.0001). Freedom from device/system‐related complications and pressure sensor failure at 2 years was 100% and 99%, respectively.

Conclusions

Remote haemodynamic‐guided HF management, using frequent assessment of pulmonary artery pressures, was successfully implemented at 14 specialist centres in the UK. Haemodynamic‐guided HF management was safe and significantly reduced hospitalization in a group of high‐risk patients. These results support implementation of this innovative remote management strategy to improve outcome for patients with symptomatic HF.

Clinical registration number: ClinicalTrials.gov identifier: NCT02954341.

Contemporary Management of Cardiogenic Shock: A RAND Appropriateness Panel Approach

BACKGROUND

Current practice in cardiogenic shock is guided by expert opinion in guidelines and scientific statements from professional societies with limited high quality randomized trial data to inform optimal patient management. An international panel conducted a modified Delphi process with the intent of identifying aspects of cardiogenic shock care where there was uncertainty regarding optimal patient management.

METHODS

An 18-person multidisciplinary panel comprising international experts was convened. A modified RAND/University of California Los Angeles appropriateness methodology was used. A survey comprising 70 statements was completed. Participants anonymously rated the appropriateness of each statement on a scale of 1 to 9: 1 to 3 inappropriate, 4 to 6 uncertain, and 7 to 9 appropriate. A summary of the results was discussed as a group, and the survey was iterated and completed again before final analysis.

RESULTS

There was broad alignment with current international guidelines and consensus statements. Overall, 44 statements were rated as appropriate, 19 as uncertain, and 7 as inappropriate. There was no disagreement with a disagreement index <1 for all statements. Routine fluid administration was deemed to be inappropriate. Areas of uncertainty focused panel on pre-PCI interventions, the use of right heart catheterization to guide management, routine use of left ventricular unloading strategies, and markers of futility when considering escalation to mechanical circulatory support.

CONCLUSIONS

While there was broad alignment with current guidance, an expert panel found several aspects of care where there was clinical equipoise, further highlighting the need for randomized controlled trials to better guide patient management and decision making in cardiogenic shock.

A clinical and cost-effectiveness analysis of the HeartMate 3 left ventricular assist device for transplant-ineligible patients: A United Kingdom perspective

BACKGROUND

The clinical and cost-effectiveness of left ventricular assist device (LVAD) therapy for patients with advanced heart failure (HF) who are ineligible for heart transplantation is debated in the UK. This study develops an indirect comparison between the fully magnetically levitated HeartMate 3 (HM 3) LVAD and medical therapy (MT) to evaluate expected clinical and cost-effectiveness in the UK National Health Service (NHS) context.

METHODS

We performed an economic analysis comparing the HM3 pump against the HeartMate II LVAD (MOMENTUM 3), and then another analysis comparing MT with the first- and second-generation HeartMate XVE pump LVAD and HeartMate II LVAD for the same patient population (REMATCH and ROADMAP, respectively). By bridging those 2 analyses, an indirect comparison between HM3 and MT in the form of a network meta-analysis was developed. A literature search was performed to select the most appropriate pair of studies for this purpose. Outcomes were adjusted to produce Kaplan-Meier curves for the cost-effectiveness evaluation by using a decision-analytic model. Data were extrapolated linearly over a 5-year time horizon. Uncertainty and additional scenarios were addressed by one-way and probabilistic sensitivity analysis. Local costs and health utility were used from England, thereby representing the UK context.

RESULTS

The incremental cost-effectiveness ratio (ICER) for LVAD vs MT in transplant ineligible patients with advanced HF was estimated to be £47,361 per quality-adjusted life year gained, with a 97.1% probability of being cost-effective at £50,000. In a subgroup of patients who are inotropic therapy dependent (INTERMACS 1-3 severity profile), the ICER was £45,616, while for a population with less-ill ambulatory HF (INTERMACS profile 4-7) the ICER changed to £64,051.

CONCLUSIONS

This study provides evidence that HM3 LVAD therapy in advanced HF patients ineligible for heart transplantation may be cost-effective compared to MT in the NHS UK-England context. The ICER is lowest for patients dependent on inotropic support, but exceeds the willingness to pay threshold of £50,000 in ambulatory noninotropic therapy dependent advanced HF patients.

Pathophysiology of severe primary graft dysfunction in orthotopic heart transplantation

BACKGROUND

A series of insults on the donor heart result in pathophysiological changes that manifest as primary graft dysfunction (PGD) post-orthotopic heart transplantation. The objectives of this study were: (i) describe the pathophysiology of severe PGD using an established cardiovascular model; and (ii) the evolution of the pathophysiology during recovery from severe PGD.

METHODS

Hemodynamic data from 20 consecutive patients with severe PGD (need for mechanical circulatory support, MCS) at baseline (T0), 6 h (T6) and "recovery" (explant of support), and 20 consecutive patients without severe PGD were used to model the pathophysiology using the cardiovascular model described by Burkhoff and Dickstein.

RESULTS

There was a progressive (from T0 to T6) up- and leftward shift in the diastolic pressure-volume relationship, especially of the right ventricle (RV), resulting in reduced capacitance. RV end-systolic elastance (Ees) was significantly elevated in severe PGD but preload-recruitable stroke work (PRSW) was significantly lower compared to patients without severe PGD. "Recovery" (after liberation from MCS) was associated with improvement in RV Ees, chamber capacitance and PRSW, although they remained significantly lower than patients without severe PGD.

CONCLUSION

Severe PGD of the dominant right heart failure phenotype is characterized by reduced chamber capacitance, increased "stiffness" and impaired contractility. Complete normalization was not required for successful weaning of MCS.

Outcomes of temporary mechanical circulatory support in cardiogenic shock due to end-stage heart failure

Background

There are few reports of mechanical circulatory support (MCS) in patients with cardiogenic shock (CS) due to end-stage heart failure (ESHF). We evaluated our institutional MCS strategy and compared the outcomes of INTERMACS 1 and 2 patients with CS due to ESHF.

Methods

Retrospective analysis of prospectively collected data (November 2014 to July 2019) from a single centre. ESHF was defined by a diagnosis of HF prior to presentation with CS. Other causes of CS (eg: acute myocardial infarction) were excluded. We compared the clinical course, complications and 90-day survival of patients with CS due to ESHF in INTERMACS profile 1 and 2.

Results

We included 60 consecutive patients with CS due to ESHF Differences in baseline characteristics were consistent with the INTERMACS profiles. The duration of MCS was similar between INTERMACS 1 and 2 patients (14 (10–33) vs 15 (7–23) days, p = 0.439). There was no significant difference in the number of patients with complications that required intervention. Compared to INTERMACS 2, INTERMACS 1 patients had more organ dysfunction on support and significant lower 90-day survival (66% vs 34%, p = 0.016).

Conclusion

Our temporary MCS strategy, including earlier intervention in patients with CS due to ESHF at INTERMACS 2 was associated with less organ dysfunction and better 90-day survival compared to INTERMACS 1 patients.

The Physiologic Basis and Clinical Outcomes of Combined Impella and Veno-Arterial Extracorporeal Membrane Oxygenation Support in Cardiogenic Shock

Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) provides effective hemodynamic support in cardiogenic shock, but in some cases may be complicated by left ventricular (LV) distension and pulmonary edema. The Impella, a catheter-mounted microaxial pump has been used to unload the LV. Recent studies have compared the clinical outcomes of VA-ECMO to the combination of Impella and VA-ECMO. The purpose of this review is threefold: firstly, to discuss the physiological effects of Impella support in addition to VA-ECMO, secondly to review published studies on the outcome of this combined support, and thirdly to provide a practical overview of the approach to combining Impella and VA-ECMO.

Harnessing lipid signaling pathways to target specialized pro-angiogenic neutrophil subsets for regenerative immunotherapy

To gain insights into neutrophil heterogeneity dynamics in the context of sterile inflammation and wound healing, we performed a pseudotime analysis of single-cell flow cytometry data using the spanning-tree progression analysis of density-normalized events algorithm. This enables us to view neutrophil transitional subsets along a pseudotime trajectory and identify distinct VEGFR1, VEGFR2, and CXCR4 high-expressing pro-angiogenic neutrophils. While the proresolving lipid mediator aspirin-triggered resolvin D1 (AT-RvD1) has a known ability to limit neutrophil infiltration, our analysis uncovers a mode of action in which AT-RvD1 leads to inflammation resolution through the selective reprogramming toward a therapeutic neutrophil subset. This accumulation leads to enhanced vascular remodeling in the skinfold window chamber and a proregenerative shift in macrophage and dendritic cell phenotype, resulting in improved wound closure after skin transplantation. As the targeting of functional immune subsets becomes the key to regenerative immunotherapies, single-cell pseudotime analysis tools will be vital in this field.

Cardiac Power Output Index and Severe Primary Graft Dysfunction After Heart Transplantation

OBJECTIVES

To evaluate the value of cardiac power output index (CPOi) in predicting severe primary graft dysfunction (PGD) after heart transplantation (defined as mechanical circulatory support [MCS] and/or mortality <30 days after transplant).

DESIGN

Observational cohort study.

SETTING

A heart transplant center in the United Kingdom.

PARTICIPANTS

Consecutive patients who underwent heart transplantation from January 2014 to December 2019 (n = 160). Twenty patients were excluded, as MCS was instituted immediately after transplant.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Hemodynamic data on return to the intensive care unit (time 0, T0) and at 6 hours (T6) were collected to calculate CPOi at both points in 140 consecutive patients-22 patients developed severe PGD. The CPOi at T0 correlated with donor-recipient predicted heart mass and inversely with inotrope score. Patients who developed severe PGD had significantly lower CPOi at T0 and T6. The areas under the receiver operating characteristic curve for CPOi at T0 and T6 for the development of severe PGD were 0.90 and 0.92, respectively. Adjusting for vasoactive-inotrope score did not improve discrimination. The probability of severe PGD if CPOi at T0 <0.34 W/m² and T6 <0.33 W/m² was 79%, but was only 2% if both CPOi at T0 and T6 were >0.34 W/m² and >0.33 W/m², respectively. After adjusting for baseline differences, CPOi at T6 (odds ratio 0.78; 95% CI 0.67-0.91, p = .001) was significantly associated with severe PGD.

CONCLUSION

Low CPOi at T0 is associated with severe PGD. Serial assessment of CPOi increases the diagnostic probability of severe PGD.

Adapting re-usable elastomeric respirators to utilise anaesthesia circuit filters using a 3D-printed adaptor - a potential alternative to address N95 shortages during the COVID-19 pandemic

The COVID‐19 pandemic has increased the demand for disposable N95 respirators. Re‐usable elastomeric respirators may provide a suitable alternative. Proprietary elastomeric respirator filters may become depleted as demand increases. An alternative may be the virus/bacterial filters used in anaesthesia circuits, if they can be adequately fitted onto the elastomeric respirators. In addition, many re‐usable elastomeric respirators do not filter exhaled breaths. If used for sterile procedures, this would also require modification. We designed a 3D‐printed adaptor that permits elastomeric respirators to interface with anaesthesia circuit filters and created a simple modification to divert exhaled breaths through the filter. We conducted a feasibility study evaluating the performance of our modified elastomeric respirators. A convenience sample of eight volunteers was recruited. Quantitative fit testing, respiratory rate and end‐tidal carbon dioxide were recorded during fit testing exercises and after 1 h of wear. All eight volunteers obtained excellent quantitative fit testing throughout the trial. The mean (SD) end‐tidal carbon dioxide was 4.5 (0.5) kPa and 4.6 (0.4) kPa at baseline and after 1 h of wear (p = 0.148). The mean (SD) respiratory rate was 17 (4) breaths.min⁻¹ and 17 (3) breaths.min⁻¹ at baseline and after 1 h of wear (p = 0.435). Four out of eight subjects self‐reported discomfort; two reported facial pressure, one reported exhalation resistance and one reported transient dizziness on exertion. Re‐usable elastomeric respirators to utilise anaesthesia circuit filters through a 3D‐printed adaptor may be a potential alternative to disposable N95 respirators during the COVID‐19 pandemic.

Pathological changes secondary to pacing leads within the coronary veins

Changes within the Coronary veins secondary to pacing leads have not been described, this study assessed these changes in explanted hearts. Macroscopically fibrous sheaths formed around longstanding leads, leading to slit like channels for venous return in smaller veins. Histologically changes included bland fibrosis, a foreign body response to the lead, a chronic inflammatory response and inflammatory destruction of the media. Individuals responded in different ways with no clear relationship of changes to duration of the lead.

Pulmonary artery pulsatility index: physiological basis and clinical application

Pulmonary artery pulsatility index (PAPi) is a haemodynamic parameter that is derived from right atrial and pulmonary artery pulse pressures. A number of reports have described the prognostic value of PAPi in patients with advanced heart failure and cardiogenic shock. However, the derivation and physiological interpretation of this parameter have received little attention. This review will examine the physiological interpretation and clinical data for PAPi.

P574Accuracy of wrist-worn heart rate monitors for chronotropic assessment in atrial fibrillation

Introduction

Wrist-worn fitness and heart rate (HR) monitors are increasingly popular. Previous studies in healthy participants with sinus rhythm (SR) have yielded variable results depending on HR, activity levels and device tested. A paucity of data exists on their accuracy in atrial fibrillation (AF) in ambulatory patients.

Purpose

We sought to assess the HR accuracy of 2 commercially available smart watches (Fitbit Charge HR [FB] and Apple Watch Series 3 [AW]) compared with Holter monitoring in an ambulant patient cohort.

Methods

Patients aged >18 years referred for 24-hour Holter monitoring were prospectively recruited. The Holter monitor was the criterion measure. Each patient was randomly allocated to either a FB or AW along with their Holter monitor. The study protocol was approved by the institutional review board.

Statistical analysis: Pearson (r) correlation coefficients and Bland-Altman comparison with 95% limits of agreement (LoA) were evaluated to assess criterion validity and agreement between the smart watch and Holter ECG-HR. Bias was the calculated mean difference between the smart watch and ECG-HR. A ± 10-beat different between Holter-HR and SW-HR was used as a clinically relevant range to establish the accuracy of HR estimation by SW.

Results

Across all devices, 53,288 hear rate values were recorded from 32 patients. Twenty six patients were in persistent AF and six were in SR. Twelve patients wore the FB while 20 wore the AW. In the FB arm, nice patient were in persistent AF and three in SR. In the AW arm, persistent AF was the rhythm in seventeen and SR in three. Patients in SR demonstrated overall strong agreement compared to Holter monitoring (Mean Bias <1 beat, LoA −11 to 11 beats) and a correlation coefficient of 0.87 (p<0.001). In AF, both devices underestimated HR measurements (Overall Bias −9 beats, LoA −41 to 23, r=0.60, p<0.001). The AW had lower bias and narrower LoA compared to FB (−5 beats vs −13 beats, LoA −31 to 21 beats vs −50 to 22 beats). Using a ± 10-beat range against ECG-HR for clinical accuracy, both the AW and FB performed satisfactorily in SR with 95.2% of AW and 92.2% of FB HR readings considered valid. In AF, however, the AW-HR readings were within the ± 10-beat threshold in 76.5% of the time compared with only 56.1% of FB readings.

Conclusion

In ambulatory patients, smart watches were accurate in HR estimation when compared to Holter monitor in SR; however tended to underestimate HR in AF. Further improvements in device technology are needed before the widespread consumer adoption of this nascent technology for chronotropic assessment in arrhythmias.

Arteriovenous fistula creation in a patient without a pulse: Vascular access in patients with left ventricular assist devices

Left ventricular assist devices are used in heart failure patients as bridge to transplantation or increasingly as a destination therapy. These patients frequently have renal dysfunction and many reach end-stage renal failure. If haemodialysis is required, minimization of infection risk is essential. Arteriovenous grafts have been recommended for these patients due to hypothetical concerns regarding fistula maturation due to continuous flow. A case is described where a brachiocephalic arteriovenous fistula was successfully formed and used for dialysis without issue. This is one case of a small number in the literature where arteriovenous fistulas have been used in left ventricular assist device patients and it appears that concerns are unfounded and good outcomes have been reported. It would appear from this experience that approaches to vascular access for dialysis in patients with continuous-flow left ventricular assist devices are in accordance with vascular access guidelines and standard practice.

Patient survival and therapeutic outcome in the UK bridge to transplant left ventricular assist device population

Objective

To study the survival and patient outcome in a population of UK patients supported by an implantable left ventricular assist device (LVAD) as a bridge to heart transplantation.

Methods

Data on all adult patients (n=342) who received a HeartMate II or HVAD as a first long-term LVAD between January 2007 and 31 December 2013 were extracted from the UK Ventricular Assist Device (VAD) Database in November 2015. Outcomes analysed include survival on a LVAD, time to urgent listing, heart transplantation and complications including those needing a pump exchange.

Results

112 patients were supported with the Thoratec HeartMate II and 230 were supported with the HeartWare HVAD. Median duration of support was 534 days. During the study period, 81 patients required moving to the UK urgent waiting list for heart transplantation. Of the 342 patients, 85 (24.8%) received a heart transplant, this included 63 on the urgent list. Thirty-day survival was 88.9%, while overall patient survival at 3 years from LVAD implant was 49.6%. 156 patients (46%) died during LVAD support; the most common cause of death on a VAD was a cerebrovascular accident. There was no significant difference between the two devices used in any outcome.

Conclusions

In a population of patients with advanced heart failure, who have a very poor prognosis, support with an implantable LVAD allowed a quarter to receive a heart transplant in a 3-year period. Overall survival of the cohort was about 50%. With improvement in technology and in post-LVAD management, it is likely that outcomes will improve further.

The interaction of Lolium latent virus major coat protein with ankyrin repeat protein NbANKr redirects it to chloroplasts and modulates virus infection

The Lolium latent virus (LoLV) major coat protein sequence contains a typical chloroplast transit peptide (cTP) domain. In infected Nicotiana benthamiana leaf tissue, LoLV coat proteins can be detected at the chloroplast. In transient expression, several N-terminal deletions of the CP sequence, increasing in length, result in disruption of the domain functionality, markedly affecting intracellular localization. A yeast two-hybrid-based study using LoLV CP as bait identified several potentially interacting Arabidopsis host proteins, most of them with chloroplast-linked pathways. One of them, an ankyrin repeat protein, was studied in detail. The N. benthamiana homologue (NbANKr) targets chloroplasts, is able to co-localize with LoLV CP at chloroplast membranes in transient expression and shows a robust interaction with LoLV CP in vivo by BiFC, which has been confirmed by yeast two-hybrid data. Silencing NbANKr genes in N. benthamiana plants, prior to challenging with LoLV by mechanical inoculation, affects LoLV infection, significantly reducing the level of viral RNA in young leaves, compared to levels in control plants, and suggesting an inhibition of virus movement. Silencing of NbANKr has no obvious effect on plant phenotype, but is able to interfere with LoLV infection, opening the way for a new strategy for virus infection control.