Deceived by the Fick principle: blood flow distribution in heart failure.

AIMS: The Fick principle states that oxygen uptake (V̇O2) is cardiac output (Qc)*arterial-venous O2 content difference [ΔC(a-v)O2]. Blood flow distribution is hidden in Fick principle and its relevance during exercise in heart failure (HF) is undefined.To highlight the role of blood flow distribution, we evaluated peak-exercise V̇O2, Qc and ΔC(a-v)O2, before and after HF therapeutic interventions. METHODS: Symptoms-limited cardiopulmonary exercise tests with Qc measurement (inert-gas-rebreathing) was performed in 234 HF patients before and 6 months after successful exercise training, cardiac-resynchronization therapy or percutaneous-edge-to-edge mitral valve repair. RESULTS: Considering all tests (n=468) a direct correlation between peakV̇O2 and peakQc (R2=0.47) and workload (R2=0.70) were observed. Patients were grouped according to treatment efficacy in group 1 (peakV̇O2 increase >10%, n=93), group 2 (peakV̇O2 change between 0 and 10%, n=60) and group 3 (reduction in peakV̇O2, n=81). Post-treatment peakV̇O2 changes poorly correlated with peakQc and peakΔC(a-v)O2 changes. Differently, post-procedures peakQc vs. peakΔC(a-v)O2 changes showed a close negative correlation (R2=0.46), becoming stronger grouping patients according to peakV̇O2 improvement (R2=0.64, 0.79 and 0.58 in group 1, 2 and 3, respectively). In 76% of patients peakQc and ΔC(a-v)O2 changes diverged regardless of treatment. CONCLUSION: The bulk of these data suggests that blood flow distribution plays a pivotal role on peakV̇O2 determination regardless of HF treatment strategies. Accordingly, for assessing HF treatment efficacy on exercise performance the sole peakV̇O2 may be deceptive and the combination of V̇O2, Qc and ΔC(a-v)O2, must be considered.

This study aimed to understand how oxygen uptake during exercise is affected by heart failure therapeutic intervention. We evaluated 234 heart failure patients before and after treatments such as exercise training, cardiac resynchronization therapy, or mitral valve repair, finding that changes in oxygen uptake were poorly correlated with changes in cardiac output and oxygen content difference between arteries and veins. However, we observed a strong negative correlation between changes in cardiac output and oxygen content difference, especially in patients with significant improvement in oxygen uptake. This suggests that blood flow distribution is crucial for oxygen uptake during exercise, regardless of treatment. Therefore, relying solely on oxygen uptake may not accurately assess treatment effectiveness, and considering a combination of oxygen uptake, cardiac output, and oxygen content difference is important. Oxygen uptake during exercise was strongly related to cardiac output and workload.Changes in cardiac output and oxygen content difference were closely related after treatments, especially in patients with significant improvement in oxygen uptake.

It's Time to Run!

Several epidemiological studies have consistently reported inverse associations between cardiorespiratory fitness and the risks of cardiovascular disease and mortality [...].

Exercise Training in Post-COVID-19 Patients: The Need for a Multifactorial Protocol for a Multifactorial Pathophysiology.

The battle against COVID-19 has entered a new phase with Rehabilitation Centres being among the major players, because the medical outcome of COVID-19 patients does not end with the control of pulmonary inflammation marked by a negative virology test, as many patients continue to suffer from long-COVID-19 syndrome. Exercise training is known to be highly valuable in patients with cardiac or lung disease, and it exerts beneficial effects on the immune system and inflammation. We therefore reviewed past and recent papers about exercise training, considering the multifactorial features characterizing post-COVID-19 patients' clinical conditions. Consequently, we conceived a proposal for a post-COVID-19 patient exercise protocol as a combination of multiple recommended exercise training regimens. Specifically, we built pre-evaluation and exercise training for post-COVID-19 patients taking advantage of the various programs of exercise already validated for diseases that may share pathophysiological and clinical characteristics with long-COVID-19.

Beta-blockers in heart failure prognosis: Lessons learned by MECKI Score Group papers.

Heart failure is a complex syndrome affecting several organs including kidney, lungs, liver, brain muscles and sympathetic system. Each of these organs might contribute to its severity and prognosis. The prognosis assessment is critical for a correct heart failure management. It has already been demonstrated that a single parameter is weaker for prognosis than different parameters combined. The Metabolic Exercise test data combined with Cardiac and Kidney Indexes (MECKI) score has been built and validated for heart failure with reduced ejection fraction (HFrEF) patients by considering cardiopulmonary exercise test data combined with clinical, laboratory and echocardiographic measurements. The betablockers treatment is a milestone in the HFrEF management. In the MECKI score database, the association of betablockers treatment with outcome has been investigated in different settings.

Effects of an Outpatient Service Rehabilitation Programme in Patients Affected by Pulmonary Arterial Hypertension: An Observational Study.

BACKGROUND: Pulmonary arterial hypertension (PAH) is a rare disease characterised by a severe impairment of functional status and quality of life (QoL). Use of rehabilitative programmes may help to improve outcomes. The aim of this pre/post test case series was to evaluate the impact of a training program, including sessions of aerobic and resistance exercise, inspiratory muscle reinforcement, slow breathing, relaxation, and psychological support, on functional outcomes. METHODS: Fifteen patients affected by PAH, in World Health Organization (WHO) Functional Class (FC) II or III and in stable clinical condition, were included in a 4-week cardiorespiratory training programme conducted in outpatient service. Patients were tested during a routine control visit (T0), one month later at the beginning of the training programme (T1), and at study end (T2). Between T0 and T1, patients continued their normal activities and therapies. At each step, patients underwent respiratory and functional evaluation by spirometry, 6-minute walk test (6-MWT), maximal cardiopulmonary exercise testing (CPET), echocardiography, and levels of brain natriuretic peptide (BNP). QoL was also assessed at T1 and T2 using the Hospital Anxiety and Depression Scale and the EuroQoL-5D questionnaire. The primary endpoint was the effect of training on peak oxygen consumption (peak V̇O2). RESULTS: There were no significant differences in BNP levels, or in any of the respiratory or echocardiographic parameters measured, between T0 and T1. Between T1 and T2, significant improvements were recorded in QoL (HADS-Anxiety mean change 3.5 ± 3.3 and HADS-Depression mean change 1.6 ± 2.0, all p < 0.01). Significant improvements were also observed in functional capacity with distance walked at 6-MWT increasing from 455 ± 115 to 487 ± 120 (+8%, p < 0.01), workload (WR) of CPET increased of 22% (from 73 ± 22 to 87 ± 21 watt, p < 0.001), peak V̇O2 increasing from 17.3 ± 4.2 to 19.9 ± 4.5 mL/kg/min (p < 0.001) and pulse O2 increasing from 7.8 ± 1.8 to 8.8 ± 2.4 mL/beat (p < 0.01). No adverse events or deterioration in clinical status were observed during the training sessions. CONCLUSION: Cardiorespiratory training in a outpatient service is a suitable option for patients with PAH in WHO FC II/III thanks to improved exercise capacity and QoL, which may allow them to achieve better outcomes.

Effect of indacaterol on lung deflation improves cardiac performance in hyperinflated COPD patients: an interventional, randomized, double-blind clinical trial.

BACKGROUND: COPD is often associated with cardiovascular comorbidity. Treatment guidelines recommend therapy with bronchodilators as first choice. We investigated the acute effect of single-dose indacaterol on lung hyperinflation in COPD subjects, for the first time evaluating the potential effects on right heart performance. METHODS: In this Phase IV, randomized, interventional, double-blind, crossover clinical study, we recruited 40 patients (50-85 years of age) with stable COPD. Patients were treated with 150 µg indacaterol or placebo and after 60 minutes (T60) and 180 minutes (T180) the following tests were performed: trans-thoracic echocardiography (TTE), plethysmography, diffusing capacity of the lung for carbon monoxide, saturation of peripheral oxygen, and visual analog scale dyspnea score. Patients underwent a crossover re-challenge after a further 72 hours of pharmacological washout. All TTE measurements were conducted blindly by the same operator and further interpreted by two different blinded operators. Consensus decisions were taken on every value and parameter. The primary outcome was the effect of the reduction of residual volume and functional residual capacity on right heart systolic and diastolic function indexes evaluated by TTE in patients treated with indacaterol, as compared to placebo. RESULTS: Vital capacity, inspiratory capacity, and forced expiratory volume in 1 second were significantly increased by indacaterol, when compared with placebo, while residual volume, intrathoracic gas volume, and specific airway resistance were significantly reduced in patients treated with indacaterol. Tricuspid annular plane systolic excursion was significantly increased versus placebo, paralleled by an increase of tricuspid E-wave deceleration time. The cardiac frequency was also significantly reduced in indacaterol-treated patients. CONCLUSION: Indacaterol significantly reduces lung hyperinflation in acute conditions, with a clinically relevant improvement of dyspnea. These modifications are associated with a significant increase of the right ventricular compliance indexes and may have a role in improving left ventricular preload leading to a reduction in cardiac frequency.

Respiratory disorders in endurance athletes - how much do they really have to endure?

Respiratory disorders are often a cause of morbidity in top level endurance athletes, more often compromising their performance and rarely being a cause of death. Pathophysiological events occurring during exercise, such as bronchospasm, are sometimes followed by clear pathological symptoms represented by asthma related to physical exertion or rarely by pulmonary edema induced by a strenuous effort. Both bronchospasm and the onset of interstitial edema induced by exercise cannot be considered pathological per se, but are more likely findings that occur in several healthy subjects once physical exhaustion during exertion has been reached. Consequently, we get a vision of the respiratory system perfectly tailored to meet the body's metabolic demands under normal conditions but which is limited when challenged by strenuous exercise, in particular when it happens in an unfavorable environment. As extreme physical effort may elicit a pathological response in healthy subjects, due to the exceeding demand in a perfectly functional system, an overview of the main tools both enabling the diagnosis of respiratory impairment in endurance athletes in a clinical and preclinical phase has also been described.

Near real-time echocardiography teleconsultation using low bandwidth and MPEG-4 compression: feasibility, image adequacy and clinical implications.

We assessed the feasibility, image adequacy and clinical utility of a tele-echocardiography service which combined video compression with low-bandwidth store-and-forward transmission. Echocardiograms were acquired by a hospital geriatrician, compressed and transmitted using both near real-time (urgent) and delayed (pre-programmed) protocols via an Internet connection to the notebook PC of a remote cardiologist. Clinical utility was evaluated as a change in therapeutic management. During a one-year period, 101 tele-echocardiography consultations were successfully performed (feasibility = 100%) on 95 patients (age 22-95 years), admitted with cardiovascular or neurological diagnoses (24% of the consultations were urgent). In total, 4617 files (1.4 GByte of data) were transmitted, 2669 of which were short video clips. On average, 46 files (13.8 MByte) were transmitted (mean duration 10 min) at each examination. Consultations (both urgent and pre-programmed) were clinically useful in 83% of examinations. Logistic regression analysis showed that both a low left ventricular systolic function and the examination indication were determinants of clinical utility. The transmitted images were considered adequate for diagnosis in 100% of the pre-programmed teleconsultations. Tele-echocardiography using MPEG-4 video compression is a feasible, adequate and clinically useful tool for telemedicine.