Development and Piloting of a Community-Partnered Heart Failure Training Course for Home Health Care Workers

BACKGROUND

Despite their unique contributions to heart failure (HF) care, home healthcare workers (HHWs) have unmet educational needs and many lack HF caregiving self-efficacy. To address this, we used a community-partnered approach to develop and pilot a HF training course for HHWs.

METHODS

We partnered with the Training and Employment Fund, a benefit fund of the largest healthcare union in the United States, to develop a 2-hour virtual HF training course that met HHWs' job-specific needs. English and Spanish-speaking HHWs interested in HF training, with access to Zoom, were eligible. We used a mixed methods design with pre/postsurveys and semi-structured interviews to evaluate the course: (a) feasibility, (b) acceptability, and (c) effectiveness (change in knowledge [Dutch Heart Failure Knowledge Scale range 0-15] and caregiving self-efficacy [HF Caregiver Self-efficacy Scale range 0-100]).

RESULTS

Of the 210 HHWs approached, 100 were eligible and agreed, and 70 enrolled. Of them, 53 (employed by 15 different home care agencies) participated. Posttraining data showed significant improvements (pretraining mean [SD] versus posttraining mean [SD]; P value) in HF knowledge (11.21 [1.90] versus 12.21 [1.85]; P=0.0000) and HF caregiving self-efficacy (75.21 [16.57] versus 82.29 [16.49]; P=0.0017); the greatest gains occurred among those with the lowest pre-training scores. Participants found the course engaging, technically feasible, and highly relevant to their scope of care.

CONCLUSIONS

We developed and piloted the first HF training course for HHWs, which was feasible, acceptable, and improved their HF knowledge and caregiving self-efficacy. Our findings warrant scalability to the workforce at large with a train-the-trainer model.

Invasive validation of pressure-volume loops derived from cardiovascular magnetic resonance imaging and brachial blood pressure in heart failure patients

Introduction

Left ventricular (LV) pressure-volume (PV) loops provide gold-standard physiological information but require invasive measurements of ventricular intracavity pressure, limiting clinical and research applications. Recent development has seen the introduction of non-invasively computed PV loops from cardiovascular magnetic resonance (CMR) volumetry and a brachial blood pressure measurement. The approach combines LV volumes with a time-varying elastance function to compute time-resolved LV pressures and was validated on invasive pressure data from a porcine model. The method is readily implemented using standard CMR sequences and provides measures of hemodynamic parameters including stroke work, myocardial efficiency, and contractile state. However, the method remains to be validated in patients using invasive left ventricular pressure recordings.

Purpose

To validate for the first time in human patients the performance of non-invasively computed PV loops against invasive measures.

Methods

Four heart failure patients underwent two subsequent sessions of CMR cine imaging and simultaneous brachial blood pressure measurement, with intravenous administration of two different vasoactive drugs, resulting in two different haemodynamic states for each patient. LV catheterization was then conducted with repeat administration of the same infusions. Pressure-volume loops were computed from CMR volumes combined with 1) a time-varying elastance function scaled to brachial blood pressure and temporally stretched to match volume data, and 2) invasive pressures averaged from multiple sampled beats. Method comparison was conducted using linear regression and Bland-Altman analysis.

Results

Figure 1 shows non-invasively derived PV loop parameters compared to invasive data. The non-invasive method demonstrated strong correlations and low bias for stroke work (R2=0.97, bias 4.6%, p<0.0001), potential energy (R2=0.83, bias 1.5%, p=0.001), end-systolic pressure-volume relationship (R2=0.90, bias 5.4%, p=0.0003), energy per ejected volume (R2=0.93, bias 3.5%, p=0.0001), ventricular efficiency (R2=0.99, bias 1.1%, p<0.0001), arterial elastance (R2=0.87, bias −7.8%, p=0.0006), and mean external power (R2=0.89, bias 4.6%, p=0.0005).

Conclusions

Pressure-volume loops can be precisely and accurately computed from cardiovascular magnetic resonance imaging and brachial cuff blood pressure in humans, and is ready for use in research applications.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Swedish Heart Lung Foundation

Assessment of fusion pacing on exercise capacity in patients with cardiac resynchronisation therapy devices

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): British Heart Foundation

Local Departmental Research Funding

Background

Cardiac resynchronisation therapy (CRT) using fusion pacing requires correct timing of left ventricular pacing to right ventricular activation. The SyncAV™ algorithm, achieves this by dynamic reassessment of intrinsic atrio-ventricular (AV) conduction to adjust the paced/sensed AV delay. However, it is unclear whether AV optimisation maintains resynchronisation during exercise, or whether loss of fusion could lead to decreased exercise capacity. Cardio-pulmonary exercise testing (CPET) is the gold standard method for assessing exercise performance and can provide prognostic information in the heart failure population.

Purpose

We therefore used CPET measures of exercise capacity to compare the SyncAV™ algorithm to conventional pacing with fixed AV delays, in a double blinded, randomised crossover study (NCT03768804).

Methods

Patients at least 6 months post-CRT implant performed 2 CPET tests at least 1 week apart, with randomisation to either SyncAV™ with fusion pacing or conventional biventricular pacing with a fixed AVD of 120ms. All other programming was optimised to produce the narrowest QRS duration possible at rest in each case.

Results

Twenty patients (11 male, age 71 [65-77] years, median [interquartile range]) were recruited, with both ischaemic and non-ischaemic aetiology of heart failure. All had clinical and/or echocardiographic response to CRT. Optimised Fixed AVD and SyncAV™programming resulted in similar narrowing of QRS duration (QRSd) from intrinsic rhythm at rest (131 [103-137] vs 134 [110-137] ms for fixed AVD and SyncAV™ groups respectively, p=0.85). Overall, there was no difference in peak oxygen consumption (V̇O2peak) between programming (14.91 [12.61-18.16] vs 15.61 [12.18-19.70] ml/kg/min, p=0.19), or oxygen consumption at anaerobic threshold (VT1) (7.36 [6.93-8.94] vs 7.87 [6.77-9.24] ml/kg/min, p=0.42), or in the time to reach either V̇O2PEAK (p=0.81) or VT1 (p=0.39). The BORG rating of perceived effort was also similar between groups. CPET performance was also analysed comparing whichever programming gave the narrowest QRSd at rest (119 [96-136] vs 134 [119-142] ms, p<0.01). Eight were narrower with fixed AVD, 8 with SyncAV™ and in 4 there was no difference. QRSd during exercise (p=0.03), peak O2 pulse (ml/beat, a surrogate of stroke volume, p=0.03) and cardiac efficiency (watts/ml/kg/min, p=0.04) were significantly improved when programmed to the narrowest QRS duration at rest.

Conclusion

There is no significant difference in exercise capacity or QRSd between the use of optimised fixed AVD or SyncAV™, lending reassurance to fusion pacing being adequately maintained on exercise. In addition, programming with whichever algorithm gives the narrowest QRSd at rest is associated with a narrower QRSd during exercise, higher peak stroke volume and improved cardiac efficiency. This supports the use of SyncAV™ in the 40% of patients where this gave the narrowest QRSd at rest.

Assessment of the SyncAV fusion pacing algorithm on exercise capacity in patients with cardiac resynchronisation therapy device

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): British Heart Foundation (BHF) and Local Departmental Research Funding

Background

Fusion pacing as part of cardiac resynchronization therapy (CRT) requires correct timing of left ventricular pacing to right ventricular activation.  The SyncAV algorithm, available in Quadra Allure and Assura CRT devices, is designed to allow optimal fusion pacing by dynamic reassessment of intrinsic atrio-ventricular (AV) conduction to adjust the paced/sensed AV delay. However, it is unclear whether AV optimisation continues to maintain resynchronisation during exercise, or whether potential loss of fusion pacing with changes in intrinsic AV conduction could lead to decreased exercise capacity. Cardio-pulmonary exercise testing (CPET) is the gold standard method for assessing exercise performance.

Purpose

To assess exercise capacity using the SyncAV algorithm for fusion pacing, compared with conventional biventricular pacing with fixed AV delays (AVD) for CRT.

Methods

 Patients at least 6 months post-CRT implant were recruited in a prospective single-centre randomized single-blind crossover study.  Patients performed 2 CPET tests at least 1 week apart, with randomization to either SyncAV with fusion pacing or conventional biventricular pacing with a fixed AVD of 120ms. All other programming was optimised to produce the narrowest QRS duration possible at rest in each case.

Results

Nine patients (5 male, age 70 ± 10 years, mean ± standard deviation) were recruited, with both ischaemic and non-ischaemic aetiology of heart failure.  All had clinical or echocardiographic response to CRT.  There was no difference in peak oxygen consumption (V̇O2max) between programming (1.47 ± 0.57 vs 1.50 ± 0.65 l/min for fixed AVD and SyncAV groups respectively, p = 0.59), or oxygen consumption at anaerobic threshold (VT1) (0.72 ± 0.20 vs 0.74 ± 0.25 l/min, p = 0.57). There was no difference in oxygen pulse (V̇O2/heart rate - a surrogate of stroke volume) at peak (12.3 ± 3.8 vs 13 ± 5.0 ml/beat , p = 0.28) or VT1 (8.4 ± 2.2 vs 8.7 ± 2.1 ml/beat, p = 0.67) and also no change in time to V̇O2max (1400 ± 491 vs 1367 ± 543 seconds, p = 0.38) or VT1 (518 ± 211 vs 534 ± 200 seconds, p = 0.75).  Average heart rate at the median stage of exercise showed no difference between programming (96 ± 18 vs 93 ± 15 bpm respectively, p = 0.32).  There was no difference in BORG Rating of Perceived Exertion (BORG-RPE) score at either peak exercise (median 19 [interquartile range (IQR) 2] vs 17 [IQR 2], p = 0.23) or at the median stage of exercise (median 13 [IQR 1] vs 13 [IQR 2], p = 0.30). 

Conclusion

Fusion pacing using the SyncAV algorithm does not appear to improve exercise capacity compared to optimised conventional biventricular pacing with fixed AVD.

Participants with diabetes have less augmentation in cardiac function and energetics in response to increased supply of fatty acid

Introduction

The Phosphocreatine (PCR)/ATP ratio is an established indicator of cardiac energetic status. Measurement of the Creatine Kinase pseudo-first order rate constant (CKkf) provides a more sensitive measure of cardiac energetics, and allows calculation of ATP delivery rate through the creatine kinase shuttle (CK flux). The normal heart is metabolically flexible, and so should maintain energetics and cardiac output regardless of substrate available (fat or glucose). This flexibility may be impaired in diabetes mellitus (DM), which may contribute to diabetic cardiomyopathy. It is unknown to what extent flexibility can be influenced by artificially altering the substrate available for metabolism.

Purpose

To compare cardiac function and energetics between diabetic and non-diabetic participants clamped on either fatty acid (FA) or glucose metabolism.

Methods

Participants with non-insulin dependent diabetic mellitus (NIDDM) and without DM (NoDM) were recruited and received intravenous infusions of either 20% fat emulsion (60ml/hr) or insulin/dextrose 20% (GLUC, variable rate) at 2 visits at least 1 week apart, before undergoing multi-parametric cardiac MRI at 3 Tesla. Cardiac volume and function, PCR/ATP ratio and CKkf (s–1) were assessed. CK flux was calculated as CKkf x PCR/ATP x 5.7 μmol (g wet weight)–1 (assumed ATP concentration).

Results

Ten NoDM participants (3 male, age 41.3±19.7 years) and 11 NIDDM participants (10 male, age 59.2±6.8 years) were recruited. Left ventricular ejection fraction (LVEF) was higher on FA in both groups (NoDM FA 63.0±3.4%; GLUC 58.1±3.8%, p=0.01; NIDDM FA 64.3±4.2%; GLUC 61.9±5.0%, p=0.05) but the increase in absolute terms was less in the NIDDM group (2.4% vs 4.9%). NoDM participants had a significantly higher CKkf on FA than GLUC (FA 0.31±0.10 s–1; GLUC 0.21±0.09 s–1, p=0.02), which did not occur in NIDDM participants (FA 0.15±0.07 s–1; GLUC 0.18±0.09 s–1, p=0.28). This was associated with a trend towards an increase in CK flux in the NoDM group which did not reach statistical significance (FA 3.50±0.99 μmol (g wet weight)–1 s–1; GLUC 2.61±1.01 μmol (g wet weight)–1 s–1, p=0.06; NIDDM FA 1.60±0.79 μmol (g wet weight)–1 s–1; GLUC 1.85±0.90 μmol (g wet weight)–1 s–1, p=0.32). There was no difference in PCR/ATP between infusions in either group (NoDM: FA 1.98±0.34; GLUC 2.05±0.30, p=0.57; NIDDM: FA 1.84±0.36; GLUC 1.85±0.24, p=0.93).

Conclusion

Increasing FA supply results in an increase in LVEF in participants with and without diabetes, but this is lower in absolute terms in diabetic participants. In non-diabetic participants this is associated with an increase in CKkf and a trend towards increased CK flux, but not in participants with NIDDM. This may reflect maximal baseline FA metabolism in participants with NIDDM and so impaired flexibility and an inability for further upregulation.

LVEF and CKkf

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): British Heart Foundation

Translational neurocardiology: preclinical models and cardioneural integrative aspects

Neuronal elements distributed throughout the cardiac nervous system, from the level of the insular cortex to the intrinsic cardiac nervous system, are in constant communication with one another to ensure that cardiac output matches the dynamic process of regional blood flow demand. Neural elements in their various 'levels' become differentially recruited in the transduction of sensory inputs arising from the heart, major vessels, other visceral organs and somatic structures to optimize neuronal coordination of regional cardiac function. This White Paper will review the relevant aspects of the structural and functional organization for autonomic control of the heart in normal conditions, how these systems remodel/adapt during cardiac disease, and finally how such knowledge can be leveraged in the evolving realm of autonomic regulation therapy for cardiac therapeutics.

Natriuretic peptides like NO facilitate cardiac vagal neurotransmission and bradycardia via a cGMP pathway

We tested the hypothesis that natriuretic peptide receptors (NPRs) that are coupled to cGMP production act in a similar way to nitric oxide (NO) by enhancing acetylcholine release and vagal-induced bradycardia. The effects of enzyme inhibitors and channel blockers on the action of atrial natriuretic peptide (ANP), brain-derived natriuretic peptide (BNP), and C-type natriuretic peptide (CNP) were evaluated in isolated guinea pig atrial-right vagal nerve preparations. RT-PCR confirmed the presence NPR B and A receptor mRNA in guinea pig sinoatrial node tissue. BNP and CNP significantly (P < 0.05) enhanced the heart rate (HR) response to vagal nerve stimulation. CNP had no effect on the HR response to carbamylcholine and facilitated the release of [(3)H]acetylcholine during atrial field stimulation. The particulate guanylyl cyclase-coupled receptor antagonist HS-142-1, the phosphodiesterase 3 inhibitor milrinone, the protein kinase A inhibitor H89, and the N-type calcium channel blocker omega-conotoxin all blocked the effect of CNP on vagal-induced bradycardia. Like NO, BNP and CNP facilitate vagal neurotransmission and bradycardia. This may occur via a cGMP-PDE3-dependent pathway increasing cAMP-PKA-dependent phosphorylation of presynaptic N-type calcium channels.

NO-cGMP pathway increases the hyperpolarisation-activated current, I(f), and heart rate during adrenergic stimulation

OBJECTIVES

The role of the nitric oxide (NO)-cGMP pathway in the autonomic modulation of cardiac pacemaking is controversial and may involve an interplay between the L-type calcium current, I(CaL), and the hyperpolarisation activated current, I(f). We tested the hypothesis that following adrenergic stimulation, the NO-cGMP pathway stimulates phosphodiesterase 2 (PDE2) to reduce cAMP dependent stimulation of I(f) and heart rate (HR).

METHODS

In the presence of norepinephrine (NE, 1 microM), the effects of the NO donor sodium nitroprusside (SNP) were evaluated in sinoatrial node (SAN)/atria preparations and isolated SAN cells from adult guinea pigs.

RESULTS

Contrary to our hypothesis, SNP (10 and 100 microM, n=5) or the membrane permeable cGMP analogue, 8Br-cGMP (0.5 mM, n=6) transiently increased HR by 5+/-1, 12+/-1 and 12+/-2 beats/min, respectively. The guanylyl cyclase inhibitor 1H-(1,2,4)-oxadiazolo-(4,3-a)-quinoxalin-1-one (ODQ, 10 microM, n=5) abolished the increase in HR to SNP (100 microM) as did the I(f) blockers caesium chloride (2 mM, n=7) and 4-(N-ethyl-N-phenylamino)-1,2-dimethyl-6-(methylamino)-pyrimidinium chloride (ZD7288, 1 microM, n=7). Addition of SNP (10 microM) also transiently increased I(f) in SAN cells (n=5). After inhibition of PDE2 with erythro-9-(2-hydroxy-3-nonyl)-adenine (EHNA, 10 microM, n=5), the increase in HR to SNP in the presence of NE was significantly augmented and maintained. RT-PCR analysis confirmed the presence of PDE2 in addition to cGMP inhibited PDE3 mRNA in central SAN tissue.

CONCLUSIONS

These results suggest that during adrenergic stimulation, activation of the NO-cGMP pathway does not decrease HR, but has a transient stimulatory effect that is I(f) dependent, and is limited in magnitude and duration by stimulation of PDE2.

Nitric oxide-cGMP pathway facilitates acetylcholine release and bradycardia during vagal nerve stimulation in the guinea-pig in vitro

1. We tested the hypothesis that nitric oxide (NO) augments vagal neurotransmission and bradycardia via phosphorylation of presynaptic calcium channels to increase vesicular release of acetylcholine. 2. The effects of enzyme inhibitors and calcium channel blockers on the actions of the NO donor sodium nitroprusside (SNP) were evaluated in isolated guinea-pig atrial-right vagal nerve preparations. 3. SNP (10 microM) augmented the heart rate response to vagal nerve stimulation but not to the acetylcholine analogue carbamylcholine (100 nM). SNP also increased the release of [3H]acetylcholine in response to field stimulation. No effect of SNP was observed on either the release of [3H] acetylcholine or the HR response to vagal nerve stimulation in the presence of the guanylyl cyclase inhibitor 1H-(1,2,4)-oxadiazolo-(4,3-a)-quinoxalin-1-one (ODQ, 10 microM). 4. The phosphodiesterase 3 (PDE 3) inhibitor milrinone (1 microM) increased the release of [3H] acetylcholine and the vagal bradycardia and prevented any further increase by SNP. SNP was still able to augment the vagal bradycardia in the presence of the protein kinase G inhibitor KT5823 (1 microM) but not after protein kinase A (PKA) inhibition with H-89 (0.5 microM) or KT5720 (1 microM) had reduced the HR response to vagal nerve stimulation. Neither milrinone nor H-89 changed the HR response to carbamylcholine. 5. SNP had no effect on the magnitude of the vagal bradycardia after inhibition of N-type calcium channels with omega-conotoxin GVIA (100 nM). 6. These results suggests that NO acts presynaptically to facilitate vagal neurotransmission via a cGMP-PDE 3-dependent pathway leading to an increase in cAMP-PKA-dependent phosphorylation of presynaptic N-type calcium channels. This pathway may augment the HR response to vagal nerve stimulation by increasing presynaptic calcium influx and vesicular release of acetylcholine.

Pre-synaptic NO-cGMP pathway modulates vagal control of heart rate in isolated adult guinea pig atria

The role of nitric oxide (NO) in the vagal modulation of heart rate (HR) is controversial. We tested the hypothesis that NO acts via a pre-synaptic, guanylyl cyclase (GC) dependent pathway. The effects of inhibiting NO synthase (NOS) and GC were evaluated in isolated atrial/right vagal nerve preparations from adult (550-750 g) and young (150-250 g) female guinea pigs. Levels of NOS protein were quantified in right atria using Western blotting and densitometry. The non-specific NOS inhibitor N- omega -nitro- L -arginine (L -NA, 100 microM, n=5) significantly reduced the negative chronotropic response to vagal nerve stimulation (VNS) at 3 and 5 Hz in the adult guinea pig. This effect was reversed with 1 m ML -arginine. Similar results were observed with the specific neuronal NOS inhibitor vinyl-N5-(1-imino-3-butenyl)- L -ornithine (L -VNIO, 100 microM, n=7). Inhibition of GC with 1H-(1,2,4)-oxadiazolo-(4, 3-a)-quinoxalin-1-one (ODQ, 10 microM, n=7) also significantly reduced the negative chronotropic response to VNS at 3 and 5 Hz in adult guinea pigs. Neither L -NA (n=6), L -VNIO (n=5) nor ODQ (n=6) changed the HR response to cumulative doses of carbamylcholine in adult guinea pig atria suggesting that the action of NO is pre-synaptic. The HR response to VNS was unaffected by L -NA (n=7) or ODQ (n=7) in young guinea pigs and Western blot analysis showed significantly lower levels of nNOS protein in right atria from young animals. These results suggest a pre-synaptic NO-cGMP pathway modulates cardiac cholinergic transmission, although this may depend on the developmental stage of the guinea pig.

Peripheral pre-synaptic pathway reduces the heart rate response to sympathetic activation following exercise training: role of NO

OBJECTIVES

We tested the hypothesis that the attenuated heart rate (HR) response to sympathetic activation following swim training in the guinea pig (Cavia porcellus) results from a peripheral modulation of pacemaking by nitric oxide (NO).

METHODS

Nitric oxide synthase (NOS) inhibition on the increase in heart rate with sympathetic nerve stimulation (SNS) was investigated in the isolated guinea pig double atrial/right stellate ganglion preparation from exercise trained (6-weeks swimming, n=20) and sedentary animals (n=20). Western blot analysis for neuronal nitric oxide synthase (nNOS) was performed on the stellate ganglion from both groups.

RESULTS

Relative to the control group, the exercise group demonstrated typical exercise adaptations of increased ventricular weight/body weight ratio, enhanced skeletal muscle citrate synthase activity and higher concentrations of [3H]ouabain binding sites in both skeletal and cardiac tissue (P<0.05). The increase in heart rate (bpm) with SNS significantly decreased in the exercise group (n=16) compared to the sedentary group (n=16) from 30+/-5 to 17+/-3 bpm at 1 Hz; 67+/-7 to 47+/-4 bpm at 3 Hz; 85+/-9 to 63+/-4 bpm at 5 Hz and 101+/-9 to 78+/-5 bpm at 7 Hz stimulation (P<0.05). The increase in heart rate with cumulative doses (0.1-10 microM) or a single dose (0.1 microM) of bath-applied norepinephrine expressed as the effective doses at which the HR response was 50% of the maximum response (EC50) were similar in both exercise (EC50 -6.08+/-0.16 M, n=8) and sedentary groups (EC50 -6.18+/-0.07 M, n=7). Trained animals had significantly more nNOS protein in left stellate ganglion compared to the sedentary group. In the exercise group, the non-isoform selective NOS inhibitor, N-omega nitro-L-arginine (L-NA, 100 microM) caused a small but significant increase in the heart rate response to SNS. However, the positive chronotropic response to sympathetic nerve stimulation remained significantly attenuated in the exercise group compared to the sedentary group during NOS inhibition (P<0.05).

CONCLUSIONS

Our results indicate that there is a significant peripheral pre-synaptic component reducing the HR response to sympathetic activation following training, although NO does not play a dominant role in this response.