Heart rate variability parameters and ventricular arrhythmia correlate with pulmonary arterial pressure in adult patients with idiopathic pulmonary arterial hypertension

Ultrasound Neuromodulation of an Anti-Inflammatory Pathway at the Spleen Improves Experimental Pulmonary Hypertension

BACKGROUND

Inflammation is pathogenically implicated in pulmonary arterial hypertension; however, it has not been adequately targeted therapeutically. We investigated whether neuromodulation of an anti-inflammatory neuroimmune pathway involving the splenic nerve using noninvasive, focused ultrasound stimulation of the spleen (sFUS) can improve experimental pulmonary hypertension.

METHODS

Pulmonary hypertension was induced in rats either by Sugen 5416 (20 mg/kg SQ) injection, followed by 21 (or 35) days of hypoxia (sugen/hypoxia model), or by monocrotaline (60 mg/kg IP) injection (monocrotaline model). Animals were randomized to receive either 12-minute-long sessions of sFUS daily or sham stimulation for 14 days. Catheterizations, echocardiography, indices of autonomic function, lung and heart histology and immunohistochemistry, spleen flow cytometry, and lung single-cell RNA sequencing were performed after treatment to assess the effects of sFUS.

RESULTS

Splenic denervation right before induction of pulmonary hypertension results in a more severe disease phenotype. In both sugen/hypoxia and monocrotaline models, sFUS treatment reduces right ventricular systolic pressure by 25% to 30% compared with sham treatment, without affecting systemic pressure, and improves right ventricular function and autonomic indices. sFUS reduces wall thickness, apoptosis, and proliferation in small pulmonary arterioles, suppresses CD3+ and CD68+ cell infiltration in lungs and right ventricular fibrosis and hypertrophy and lowers BNP (brain natriuretic peptide). Beneficial effects persist for weeks after sFUS discontinuation and are more robust with early and longer treatment. Splenic denervation abolishes sFUS therapeutic benefits. sFUS partially normalizes CD68+ and CD8+ T-cell counts in the spleen and downregulates several inflammatory genes and pathways in nonclassical and classical monocytes and macrophages in the lung. Differentially expressed genes in those cell types are significantly enriched for human pulmonary arterial hypertension-associated genes.

CONCLUSIONS

sFUS causes dose-dependent, sustained improvement of hemodynamic, autonomic, laboratory, and pathological manifestations in 2 models of experimental pulmonary hypertension. Mechanistically, sFUS normalizes immune cell populations in the spleen and downregulates inflammatory genes and pathways in the lung, many of which are relevant in human disease.

Continuous long-term heart rate variability and risk assessment in pulmonary hypertension

OBJECTIVE

Current multimodal risk assessment for pulmonary hypertension (PH) has been redefined with a simplified assessment for follow-up in the new European Society of Cardiology/European Respiratory Society (ESC/ERS) guidelines. Follow-up risk assessment parameters include WHO functional class, 6 min walk test and N-terminal pro-brain natriuretic peptide. Although these parameters have prognostic implications assessment reflect data relating to specific time points.

METHODS

Patients diagnosed with PH received an implantable loop recorder (ILR) to monitor daytime and night-time heart rate (HR), HR variability (HRV) and daily physical activity. Associations between the ILR measurements and established risk parameters were analysed using correlations, linear mixed models as well as logistical mixed models for addressing the ESC/ERS risk-score.

RESULTS

41 patients (median age: 56 years, range: 44-61.5 years) were included. Continuous monitoring had a median duration of 755 days (range: 343-1138 days), totalling 96 patient-years. In the linear mixed models, HRV and physical activity indexed by daytime HR (PAiHR) were significantly associated with the ERS/ERC risk parameters. In a logistical mixed model, HRV revealed a significant difference between 1-year mortality (<5% vs >5%) (p=0.027) with an OR of 0.82 for being in the group with 1-year mortality >5% for every increase by one HRV unit.

CONCLUSIONS

Risk assessment in PH can be refined with continuous monitoring of HRV and PAiHR. These markers were associated with the ESC/ERC parameters. Our study with continuous risk stratification in PH demonstrated that a lower HRV predict worse prognosis.

Effects of Acute Hypoxia on Heart Rate Variability in Patients with Pulmonary Vascular Disease

Pulmonary vascular diseases (PVDs), defined as arterial or chronic thromboembolic pulmonary hypertension, are associated with autonomic cardiovascular dysregulation. Resting heart rate variability (HRV) is commonly used to assess autonomic function. Hypoxia is associated with sympathetic overactivation and patients with PVD might be particularly vulnerable to hypoxia-induced autonomic dysregulation. In a randomised crossover trial, 17 stable patients with PVD (resting PaO₂ ≥ 7.3 kPa) were exposed to ambient air (FiO₂ = 21%) and normobaric hypoxia (FiO₂ = 15%) in random order. Indices of resting HRV were derived from two nonoverlapping 5-10-min three-lead electrocardiography segments. We found a significant increase in all time- and frequency-domain HRV measures in response to normobaric hypoxia. There was a significant increase in root mean squared sum difference of RR intervals (RMSSD; 33.49 (27.14) vs. 20.76 (25.19) ms; p < 0.01) and RR50 count divided by the total number of all RR intervals (pRR50; 2.75 (7.81) vs. 2.24 (3.39) ms; p = 0.03) values in normobaric hypoxia compared to ambient air. Both high-frequency (HF; 431.40 (661.56) vs. 183.70 (251.25) ms²; p < 0.01) and low-frequency (LF; 558.60 (746.10) vs. 203.90 (425.63) ms²; p = 0.02) values were significantly higher in normobaric hypoxia compared to normoxia. These results suggest a parasympathetic dominance during acute exposure to normobaric hypoxia in PVD.

Validity and reliability of short-term heart-rate variability from disposable electrocardiography leads

Background and Aims

Single-use electrocardiography (ECG) leads have been developed to reduce healthcare-associated infection. This study compared the validity and reliability of short-term heart rate variability (HRV) obtained from single-use disposable ECG leads.

Methods

Thirty healthy subjects (33 ± 10 years; 9 females) underwent 5-min resting HRV assessments using disposable (single use) ECG cable and wire system (Kendall DL™ Cardinal Health) and a standard, reusable ECG leads (CardioExpress, Spacelabs Healthcare).

Results

Intraclass correlation coefficient (ICC) with 95% confidence interval (CI) between disposable and reusable ECG leads was for the time domain [R-R interval (ms); 0.99 (0.91, 1.00)], the root mean square of successive normal R-R interval differences (RMSSD) (ms); 0.91 (0.76, 0.96), the SD of normal-to-normal R-R intervals (SDNN) (ms); 0.91 (0.68, 0.97) and frequency domain [low-frequency (LF) normalized units (nu); 0.90 (0.79, 0.95), high frequency (HF) nu; 0.91 (0.80, 0.96), LF power (ms²); 0.89 (0.62, 0.96), HF power (ms²); 0.90 (0.72, 0.96)] variables. The mean difference and upper and lower limits of agreement between disposable and reusable leads for time- and frequency-domain variables were acceptable. Analysis of repeated measures using disposable leads demonstrated excellent reproducibility (ICC 95% CI) for R-R interval (ms); 0.93 (0.85, 0.97), RMSSD (ms); 0.93 (0.85, 0.97), SDNN (ms); 0.88 (0.75, 0.95), LF power (ms²); 0.87 (0.72, 0.94), and HF power (ms²); 0.88 (0.73, 0.94) with coefficient of variation ranging from 2.2% to 5% (p > 0.37 for all variables).

Conclusion

Single-use Kendall DL™ ECG leads demonstrate a valid and reproducible tool for the assessment of HRV.

Incidence and prognostic significance of malignant arrhythmias during (repetitive) Holter electrocardiograms in patients with pulmonary hypertension

Background

In patients with pulmonary hypertension (PH), increased pulmonary vascular resistance (PVR) may lead to increased right ventricular afterload and cardiac remodelling, potentially providing the substrate for ventricular arrhythmias. Studies dealing with long term monitoring of patients with PH are rare. The present study evaluated the incidence and the types of arrhythmias retrospectively recorded by Holter ECG in patients with newly detected PH during a long-term Holter ECG follow-up. Moreover, their impact on patient survival was evaluated.

Patients and methods

Medical records were screened for demographic data, aetiology of PH, incidence of coronary heart disease, level of brain natriuretic peptide (BNP), results from Holter ECG monitoring, 6-minute walk test distance, echocardiographic data and hemodynamic data derived from right heart catheterization. Two subgroups were analyzed: 1. patients (n = 65) with PH (group 1 + 4) and derivation of at least 1 Holter ECG within 12 months from initial detection of PH and 2. patients (all PH etiologies, n = 59) with 3 follow-up Holter ECGs. The frequency and complexity of premature ventricular contractions (PVC) was classified into "lower" and "higher" (=non sustained ventricular tachycardia, nsVT) burden.

Results

Holter ECG revealed sinus rhythm (SR) in most of the patients (n = 60). Incidence of atrial fibrillation (AFib) was low (n = 4). Patients with premature atrial contractions (PAC) tend to have a shorter period of survival (p = 0.098), PVC were not correlated with significant survival differences. During follow-up PAC and PVC were common in all PH groups. Holter ECG revealed non sustained ventricular tachycardia in 19/59 patients [(32.2%); n = 6 during first Holter-ECG, n = 13 during second/third Holter-ECG]. In all patients suffering from nsVT during follow-up previous Holter ECG revealed multiform/repetitive PVC. PVC burden was not linked to differences in systolic pulmonary arterial pressure, right atrial pressure, brain natriuretic peptide and results of six-minute walk test.

Conclusion

Patients with PAC tend to have a shortened survival. None of the evaluated parameters (BNP, TAPSE, sPAP) was correlated with the development of arrhythmias. Patients with multiform/repetitive PVC seem to be at risk for ventricular arrhythmias.

Does transcatheter ventricular septal defect closure affect heart rate variability in children?

BACKGROUND

Heart rate variability (HRV) is a sign of the cardiac autonomic nervous system. Its evaluation in pediatric ventricular septal defect (VSD) cases before and after transcatheter closure contributes to an understanding of cardiac autonomic control.

METHODS

Nineteen children with VSDs treated with transcatheter closure and 18 healthy children were enrolled in this study. A 24-h Holter rhythm monitor was applied to all patients before VSD closure and to those in the control group. Holter rhythm monitoring was repeated at three months in the patient group. HRV parameters were measured using the Cardio Scan Premier 12® program. Frequency-domain (total power; very-low-frequency, low-frequency (LF), and high-frequency (HF) indices; and the LF/HF ratio) and time-domain (standard deviation of all RR intervals (SDNN), standard deviation of 5-min averages of RR intervals (SDANN), the SDNN index, percentage of the difference between adjacent RR intervals, and the square root of the mean of the sum of square differences between adjacent filtered RR intervals) parameters were assessed.

RESULTS

Before the procedure, SDNN, SDANN, and total power values were lower in the patient group than in the control group; other parameters were similar in the two groups. No significant difference in the SDNN, SDANN, or total power was detected between the patient and control groups in the third month, indicating that autonomic control of patients' hearts became normal during the third postoperative month. No correlation was detected between any hemodynamic parameters and any time-domain or frequency-domain parameters before closure.

CONCLUSION

This study showed that transcatheter closure of VSDs changed HRV parameters in pediatric patients.

The Systolic Pulmonary Arterial Pressure Liaises Impaired Cardiac Autonomic Control to Pro-inflammatory Status in Systemic Sclerosis Patients

The current study was undertaken to test the hypothesis that systemic sclerosis (SSc) patients with higher systolic pulmonary arterial pressures (PAPs) present a blunted cardiac autonomic modulation and a pro-inflammatory profile. Thirty-nine SSc patients were enrolled (mean age 57 ± 11 years). ECG and respiration were recorded in the supine (SUP) position and during the active standing (ORT). Heart rate variability (HRV) analysis was performed on samples of 300 beats. The symbolic analysis identified three patterns, 0V%, (sympathetic) and 2UV% and 2LV%, (vagal). The %ΔORT was calculated from the differences between HRV in ORT and SUP, normalized (%) by the HRV values at rest. The PAPs was obtained non-invasively through echocardiography. For the inter-group analysis, participants were allocated in groups with higher (+PAPs ≥ median) and lower PAPs (–PAPs < median) values. At rest, the cardiac sympathetic modulation (represented by 0V%) was positively correlated with PAPs, while parasympathetic modulation (represented by 2LV%) was negatively correlated with PAPs. The dynamic response to ORT (represented by Δ0V% and Δ2LV%), sympathetic and parasympathetic were negatively and positively correlated with PAPs, respectively. The +PAPs group presented a higher inflammatory status and a blunted cardiac autonomic response to ORT (↓Δ0V% and ↑Δ2LV%) compared to the –PAPs group. These findings suggest an interplay among cardiac autonomic control, inflammatory status, and cardiopulmonary mechanics that should be considered for the assessment, monitoring, and treatment of SSc patients.

Cardiac baroreflex dysfunction in patients with pulmonary arterial hypertension at rest and during orthostatic stress: role of the peripheral chemoreflex

The baroreflex integrity in early-stage pulmonary arterial hypertension (PAH) remains uninvestigated. A potential baroreflex impairment could be functionally relevant and possibly mediated by enhanced peripheral chemoreflex activity. Thus, we investigated 1) the cardiac baroreflex in nonhypoxemic PAH; 2) the association between baroreflex indexes and peak aerobic capacity [i.e., peak oxygen consumption (V̇o_2peak)]; and 3) the peripheral chemoreflex contribution to the cardiac baroreflex. Nineteen patients and 13 age- and sex-matched healthy adults (HA) randomly inhaled either 100% O₂ (peripheral chemoreceptor inhibition) or 21% O₂ (control session) while at rest and during a repeated sit-to-stand maneuver. Beat-by-beat analysis of R-R intervals and systolic blood pressure provided indexes of cardiac baroreflex sensitivity (cBRS) and effectiveness (cBEI). The PAH group had lower cBEI for all sequences (cBEI_ALL) at rest [means ± SD: PAH = 0.5 ± 0.2 vs. HA = 0.7 ± 0.1 arbitrary units (a.u.), P = 0.02] and lower cBRS_ALL (PAH = 6.8 ± 7.0 vs. HA = 9.7 ± 5.0 ms·mmHg^-1, P < 0.01) and cBEI_ALL (PAH = 0.4 ± 0.2 vs. HA= 0.6 ± 0.1 a.u., P < 0.01) during the sit-to-stand maneuver versus the HA group. The cBEI during the sit-to-stand maneuver was independently correlated to V̇o_2peak (partial r = 0.45, P < 0.01). Hyperoxia increased cBRS and cBEI similarly in both groups at rest and during the sit-to-stand maneuver. Therefore, cardiac baroreflex dysfunction was observed under spontaneous and, most notably, provoked blood pressure fluctuations in nonhypoxemic PAH, was not influenced by the peripheral chemoreflex, and was associated with lower V̇o_2peak, suggesting that it could be functionally relevant.NEW & NOTEWORTHY Does the peripheral chemoreflex play a role in cardiac baroreflex dysfunction in patients with pulmonary arterial hypertension (PAH)? Here we provide new evidence of cardiac baroreflex dysfunction under spontaneous and, most notably, provoked blood pressure fluctuations in patients with nonhypoxemic PAH. Importantly, impaired cardiac baroreflex effectiveness during provoked blood pressure fluctuations was independently associated with poorer functional capacity. Finally, our results indicated that the peripheral chemoreflex did not mediate cardiac baroreflex dysfunction among those patients.

Effects of nasal high flow on sympathovagal balance, sleep, and sleep-related breathing in patients with precapillary pulmonary hypertension

BACKGROUND

In precapillary pulmonary hypertension (PH), nasal high flow therapy (NHF) may favorably alter sympathovagal balance (SVB) and sleep-related breathing through washout of anatomical dead space and alleviation of obstructive sleep apnea (OSA) due to generation of positive airway pressure.

OBJECTIVES

To investigate the effects of NHF on SVB, sleep, and OSA in patients with PH, and compare them with those of positive airway pressure therapy (PAP).

METHODS

Twelve patients with PH (Nice class I or IV) and confirmed OSA underwent full polysomnography, and noninvasive monitoring of SVB parameters (spectral analysis of heart rate, diastolic blood pressure variability). Study nights were randomly split into four 2-h segments with no treatment, PAP, NHF 20 L/min, or NHF 50 L/min. In-depth SVB analysis was conducted on 10-min epochs during daytime and stable N2 sleep at nighttime.

RESULTS

At daytime and compared with no treatment, NHF20 and NHF50 were associated with a flow-dependent increase in peripheral oxygen saturation but a shift in SVB towards increased sympathetic drive. At nighttime, NHF20 was associated with increased parasympathetic drive and improvements in sleep efficiency, but did not alter OSA severity. NHF50 was poorly tolerated. PAP therapy improved OSA but had heterogenous effects on SVB and neutral effects on sleep outcomes. Hemodynamic effects were neutral for all interventions.

CONCLUSIONS

In sleeping PH patients with OSA NHF20 but not NHF50 leads to decreased sympathetic drive likely due to washout of anatomical dead space. NHF was not effective in lowering the apnea-hypopnoea index and NHF50 was poorly tolerated.

Predicting Heart Rate Variability Parameters in Healthy Korean Adults: A Preliminary Study

The purpose of the study was to examine the development of a multiple linear regression model to estimate heart rate variability (HRV) parameters using easy-to-measure independent variables in preliminary experiments. HRV parameters (time domain: SDNN, RMSSD, NN50, pNN50; frequency domain: TP, VLF, LF, HF) and the independent variables (e.g., sex, age, body height, body weight, BMI, HR, HR_max, HRR) were measured in 75 healthy adults (male n = 27, female n = 48) for estimating HRV. The HRV estimation multiple linear regression model was developed using the backward elimination technique. The regression model’s coefficient of determination for the time domain variables was significantly high (SDNN = R²: 72.2%, adjusted R²: 69.8%, P < .001; RMSSD = R²: 93.1%, adjusted R²: 92.1%, P < .001; NN50 = R²: 78.0%, adjusted R²: 74.9%, P < .001; pNN50 = R²: 89.1%, adjusted R²: 87.4%, P < .001). The coefficient of determination of the regression model for the frequency domain variable was moderate (TP = R²: 75.6%, adjusted R²: 72.6%, P < .001; VLF = R²: 41.6%, adjusted R²: 40.3%, P < .001; LF = R²: 54.6%, adjusted R²: 49.2%, P < .001; HF = R²: 67.5%, adjusted R²: 63.4%, P < .001). The coefficient of determination of time domain variables in the developed multiple regression models was shown to be very high (adjusted R²: 69.8%–92.1%, P < .001), but the coefficient of determination of frequency domain variables was moderate (adjusted R²: 40.3%–72.6%, P < .001). In addition to the equipment used for measuring HRV in clinical trials, this study confirmed that simple physiological variables could predict HRV.

Evaluation of the Autonomic Nervous System in a Canine Model of Chronic Embolic Pulmonary Hypertension

BACKGROUND

Sildenafil improves autonomic dysfunction caused by pulmonary hypertension (PH) in humans, but its effect is unknown in dogs with PH. This prospective study aimed to evaluate the autonomic nervous system function of a canine model of chronic embolic PH (CEPH) and the autonomic nervous system function of a canine model of CEPH in which sildenafil was administered.

METHODS

This study used five clinically healthy female beagle dogs. Evaluation parameters included hemodynamic parameters, heart rate (HR) and heart rate variability (HRV). Each evaluation parameter was compared before and after creating the CEPH model (before, BL; after, CEPH_BL) and between the CEPH_BL model and after the administration of sildenafil (1 mg/kg, BID) in the CEPH model dogs (CEPH_Sil).

RESULTS

In the CEPH_BL model, the hemodynamic parameters indicated cardiac hypofunction, and HR was significantly increased and HRV was significantly decreased compared with BL. Further, in the CEPH_Sil model, the hemodynamic parameters suggested improvement in cardiac function, and HRV was significantly increased.

CONCLUSIONS

From the results of the CEPH model dogs, autonomic dysfunction was shown to occur in PH dogs. In addition, the administration of 1 mg/kg of sildenafil to CEPH model dogs may improve autonomic dysfunction.

Soares PP, Montano N, Aliberti S, Blasi F. Sympatho-Vagal Dysfunction in Patients with End-Stage Lung Disease Awaiting Lung Transplantation

Although the literature demonstrates that cardiac autonomic control (CAC) might be impaired in patients with chronic pulmonary diseases, the interplay between CAC and disease severity in end-stage lung disease has not been studied yet. We investigated the effects of end-stage lung disease on CAC through the analysis of heart rate variability (HRV) among patients awaiting lung transplantation. Forty-nine patients on the waiting list for lung transplantation (LTx; 19 men, age 38 ± 15 years) and 49 healthy non-smoking controls (HC; 22 men, age 40 ± 16 years) were enrolled in a case-control study at Policlinico Hospital in Milan, Italy. LTx patients were divided into two groups, according to disease severity evaluated by the Lung Allocation Score (LAS). To assess CAC, electrocardiogram (ECG) and respiration were recorded at rest for 10 min in supine position and for 10 min during active standing. Spectral analysis identified low and high frequencies (LF, sympathetic, and HF, vagal). Symbolic analysis identified three patterns, i.e., 0V% (sympathetic) and 2UV% and 2LV% (vagal). Compared to HCs, LTx patients showed higher markers of sympathetic modulation and lower markers of vagal modulation. However, more severely affected LTx patients, compared to less severely affected ones, showed an autonomic profile characterized by loss of sympathetic modulation and predominant vagal modulation. This pattern can be due to a loss of sympathetic rhythmic oscillation and a subsequent prevalent respiratory modulation of heart rate in severely affected patients.

Systemic Consequences of Pulmonary Hypertension and Right-Sided Heart Failure

Pulmonary hypertension (PH) is a feature of a variety of diseases and continues to harbor high morbidity and mortality. The main consequence of PH is right-sided heart failure which causes a complex clinical syndrome affecting multiple organ systems including left heart, brain, kidneys, liver, gastrointestinal tract, skeletal muscle, as well as the endocrine, immune, and autonomic systems. Interorgan crosstalk and interdependent mechanisms include hemodynamic consequences such as reduced organ perfusion and congestion as well as maladaptive neurohormonal activation, oxidative stress, hormonal imbalance, and abnormal immune cell signaling. These mechanisms, which may occur in acute, chronic, or acute-on-chronic settings, are common and precipitate adverse functional and structural changes in multiple organs which contribute to increased morbidity and mortality. While the systemic character of PH and right-sided heart failure is often neglected or underestimated, such consequences place additional burden on patients and may represent treatable traits in addition to targeted therapy of PH and underlying causes. Here, we highlight the current state-of-the-art understanding of the systemic consequences of PH and right-sided heart failure on multiple organ systems, focusing on self-perpetuating pathophysiological mechanisms, aspects of increased susceptibility of organ damage, and their reciprocal impact on the course of the disease.

[Tachycardia and pulmonary arterial hypertension]

Pulmonary hypertension is newly defined as an elevation of the mean pulmonary arterial pressure >20 mmHg and a pulmonary vascular resistance ≥3 Wood units. Arrhythmias are an increasing problem in patients with pulmonary hypertension. Pathophysiological aspects leading to supraventricular arrhythmias are atrial fibrosis caused by increased right atrial pressure and dilation. An increased sympathetic tone leads to prolongation of action potential and delayed polarisations causing arrhythmias. Therapy of arrhythmias includes drugs (preferred amiodarone) and electrophysiological therapy like electric cardioversion and ablation, which is safe in patients with pulmonary hypertension.

Heart rate variability in pulmonary hypertension with and without sleep apnea

Objectives

Our aims were to evaluate HRV in pulmonary hypertension (WHO Group 1 and 4) compared to control subjects, and to assess whether the presence of sleep apnea in those with pulmonary hypertension would be deleterious and cause greater impairment in HRV.

Methods

This retrospective case-control study analyzed electrocardiogram segments obtained from diagnostic polysomnography.

Results

Forty-one pulmonary hypertension patients were compared to 41 age, sex and apnea-hypopnea index matched healthy controls. The pulmonary hypertension group had decreased high frequency, very low frequency, low frequency, and percentage of normal R-R intervals that differ by > 50 ms compared to control subjects. Moderate to severe right ventricle dysfunction on echocardiography was a predictor of lower high frequency in pulmonary hypertension patients.

Conclusions

There were no differences in any HRV measures in pulmonary hypertension patients with or without sleep apnea. Impaired HRV was demonstrated in pulmonary hypertension patients however, the presence of sleep apnea did not appear to further reduce vagal modulation.

Pathophysiology, incidence, management, and consequences of cardiac arrhythmia in pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension

Arrhythmias are increasingly recognized as serious, end-stage complications of pre-capillary pulmonary hypertension, including pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH). Although arrhythmias contribute to symptoms, morbidity, in-hospital mortality, and possibly sudden death in PAH/CTEPH, there remains a paucity of epidemiologic, pathophysiologic, and outcome data to guide management of these patients. This review summarizes the most current evidence on the topic: from the molecular mechanisms driving arrhythmia in the hypertrophied or failing right heart, to the clinical aspects of epidemiology, diagnosis, and management.

Low heart rate variability relates to the progression of gastric cancer

BACKGROUND

Gastric cancer (GC) is one of the most common malignant gastrointestinal tumors with the high morbidity and mortality, affecting the quality of human life. This study aimed to identify the role of heart rate variability (HRV) in patients with GC.

METHODS

From January 2010 to June 2014, 383 consecutive patients diagnosed with GC were enrolled in this study. Clinical and pathological information from each patient were retrospectively recorded. HRV, including standard deviation of normal-to-normal RR intervals (SDNN) and root mean square of successive differences (RMSSD), were measured by electrocardiography.

RESULTS

The results showed that the SDNN and RMSSD in GC patients were 19.02 ± 13.58 ms and 21.64 ± 17.57 ms, respectively. HRV decreased with advanced clinical stage (P < 0.0001). HRV correlated with tumor size, tumor infiltration, lymph node metastasis and distant metastasis (P < 0.001); however, no correlation with tumor site and metastasis severity was found (P > 0.05). C-reactive protein (CRP) was higher in the low HRV group than that in high HRV group (P = 0.008).

CONCLUSIONS

GC patients showed a lower HRV that was correlated with tumor stage. HRV decreased with tumor progression, which may be related to a mechanism involving vagal nerve excitement inhibiting the inflammatory reaction.

Autonomic nervous system involvement in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a chronic pulmonary vascular disease characterized by increased pulmonary vascular resistance (PVR) leading to right ventricular (RV) failure. Autonomic nervous system involvement in the pathogenesis of PAH has been demonstrated several years ago, however the extent of this involvement is not fully understood. PAH is associated with increased sympathetic nervous system (SNS) activation, decreased heart rate variability, and presence of cardiac arrhythmias. There is also evidence for increased renin-angiotensin-aldosterone system (RAAS) activation in PAH patients associated with clinical worsening. Reduction of neurohormonal activation could be an effective therapeutic strategy for PAH. Although therapies targeting adrenergic receptors or RAAS signaling pathways have been shown to reverse cardiac remodeling and improve outcomes in experimental pulmonary hypertension (PH)-models, the effectiveness and safety of such treatments in clinical settings have been uncertain. Recently, novel direct methods such as cervical ganglion block, pulmonary artery denervation (PADN), and renal denervation have been employed to attenuate SNS activation in PAH. In this review, we intend to summarize the multiple aspects of autonomic nervous system involvement in PAH and overview the different pharmacological and invasive strategies used to target autonomic nervous system for the treatment of PAH.

Validity of the Polar V800 heart rate monitor to measure RR intervals at rest

Purpose

To assess the validity of RR intervals and short-term heart rate variability (HRV) data obtained from the Polar V800 heart rate monitor, in comparison to an electrocardiograph (ECG).

Method

Twenty participants completed an active orthostatic test using the V800 and ECG. An improved method for the identification and correction of RR intervals was employed prior to HRV analysis. Agreement of the data was assessed using intra-class correlation coefficients (ICC), Bland–Altman limits of agreement (LoA), and effect size (ES).

Results

A small number of errors were detected between ECG and Polar RR signal, with a combined error rate of 0.086 %. The RR intervals from ECG to V800 were significantly different, but with small ES for both supine corrected and standing corrected data (ES <0.001). The bias (LoA) were 0.06 (−4.33 to 4.45 ms) and 0.59 (−1.70 to 2.87 ms) for supine and standing intervals, respectively. The ICC was >0.999 for both supine and standing corrected intervals. When analysed with the same HRV software no significant differences were observed in any HRV parameters, for either supine or standing; the data displayed small bias and tight LoA, strong ICC (>0.99) and small ES (≤0.029).

Conclusions

The V800 improves over previous Polar models, with narrower LoA, stronger ICC and smaller ES for both the RR intervals and HRV parameters. The findings support the validity of the Polar V800 and its ability to produce RR interval recordings consistent with an ECG. In addition, HRV parameters derived from these recordings are also highly comparable.

Ventricular tachycardias in patients with pulmonary hypertension: an underestimated prevalence? A prospective clinical study

BACKGROUND

Sudden cardiac death (SCD) accounts for approximately 30 % in patients with pulmonary arterial hypertension (PAH). The exact circumference for SCD in this patient population is still unclear. Malignant cardiac arrhythmias are reported to be rarely present. There are no systematic data concerning long-term electrocardiographic (ECG) recording in patients with PAH.

OBJECTIVES

We sought to investigate the rate of potentially relevant arrhythmias in patients with pulmonary hypertension (PH).

METHODS

Consecutive patients without diagnosis of known cardiac arrhythmias followed in our outpatient clinic for PH were enrolled in the study. All patients underwent a 72-h Holter ECG. Clinical data, 6-min walk distance, laboratory values, and echocardiography were collected/performed.

RESULTS

Ninety-two consecutive patients (New York Heart Association class (NYHA) III/IV: 65.2 %/5.4 %, PH Group 1: 35.9 %, Group 3: 10.9 %, Group 4: 28.3 %, Group 5: 2.2 %) were investigated. Relevant arrhythmias were newly detected in 17 patients: non-sustained ventricular tachycardia (n = 12), intermittent second-degree heart block (n = 1), intermittent third-degree heart block (n= 3), and atrial flutter (n = 1). Echocardiographic systolic pulmonary pressure and diameter of the right heart were elevated in patients with relevant arrhythmias. Right heart catheterization revealed higher pulmonary vascular resistance (672 vs. 542 dyn · s · cm(-5), p = 0.247) and lower cardiac index (2.46 vs. 2.82 l/min/m(2), p = 0.184).

CONCLUSIONS

Ventricular tachycardias occur more often in PH patients than previously reported. However, the prognostic relevance of non-sustained ventricular tachycardias in this cohort remains unclear. As a large number of PH patients die from SCD, closer monitoring, e.g., using implantable event recorders, might be useful to identify patients at high risk.