Long-term stress exposure, cortisol level and cardiovascular activity and reactivity: Observations in patients with fibromyalgia.

Previous research suggested that exposure to long-lasting or repeated laboratory stressors may lead to rearrangement of cardiovascular control, with a shift of regulation mechanisms from dominant cardiac to dominant vascular influences between the early and late response phases, respectively. This study investigated whether similar rearrangement occurs during life stress accompanying chronic disease by analyzing also associations between cortisol level and cardiovascular variables in patients with fibromyalgia (FM). In 47 women with FM and 36 healthy women (HW), cardiovascular recordings were taken during active body posture changes (sitting, lying down, and standing). Moreover, hair cortisol concentration (HCC) was obtained. During standing, which involved orthostatic challenge, FM patients showed higher total peripheral resistance (TPR) but lower stroke volume (SV), cardiac output (CO), and baroreflex sensitivity than HW. During sitting and lying down, TPR was more closely associated with blood pressure (BP) than CO in FM patients; in contrast, CO was more closely associated with BP than TPR in HW. HCC correlated positively with TPR and BP in FM patients, but negatively with TPR and BP and positively with SV and CO in HW. Results suggest that chronic disease-related stress is associated with alterations in cardiovascular regulation toward greater involvement of vascular than cardiac mechanisms in BP control. Stress-related cortisol release may contribute to the long-term rearrangement of autonomic regulation. At the behavioral level, the dominance of vascular over cardiovascular control may relate to reduced somatic mobilization during an active fight-flight response in favor of passive and behaviorally immobile coping.

Non-invasive pulse arrival time is associated with cardiac index in pediatric heart transplant patients with normal ejection fraction.

OBJECTIVE: Cardiac Index (CI) is a key physiologic parameter to ensure end organ perfusion in the pediatric intensive care unit (PICU). Determination of CI requires invasive cardiac measurements and is not routinely done at the PICU bedside. To date, there is no gold standard non-invasive means to determine CI. This study aims to use a novel non-invasive methodology, based on routine continuous physiologic data, called Pulse Arrival Time (PAT) as a surrogate for CI in patients with normal Ejection Fraction. Approach: Electrocardiogram (ECG) and photoplethysmogram (PPG) signals were collected from beside monitors at a sampling frequency of 250 samples per second. Continuous PAT, derived from the ECG and PPG waveforms was averaged per patient. Pearson's correlation coefficient was calculated between PAT and CI, PAT and heart rate (HR), and PAT and ejection fraction (EF). Main Results: Twenty patients underwent right heart cardiac catheterization. The mean age of patients was 11.7±5.4 years old, ranging from 11 months old to 19 years old, the median age was 13.4 years old. HR in this cohort was 93.8±17.0 beats per minute. The average EF was 54.4±9.6%. The average CI was 3.51±0.72 L/min/m2, with ranging from 2.6 to 4.77 L/min/m2. The average PAT was 0.31±0.12 seconds. Pearson correlation analysis showed a positive correlation between PAT and CI (0.57, p < 0.01). Pearson correlation between HR and CI, and correlation between EF and CI was 0.22 (p = 0.35) and 0.03 (p = 0.23) respectively. The correlation between PAT, when indexed by HR (i.e. PAT × HR), and CI minimally improved to 0.58 (p < 0.01). Significance: This pilot study demonstrates that PAT may serve as a valuable surrogate marker for CI at the bedside, as a non-invasive and continuous modality in the PICU. The use of PAT in clinical practice remains to be thoroughly investigated. .

Centhaquine Increases Stroke Volume and Cardiac Output in Patients with Hypovolemic Shock.

Introduction: Centhaquine is a resuscitative agent that acts on α2B adrenergic receptors. Its effect on cardiac output in hypovolemic shock patients has not been reported. Methods: This pilot study was conducted in 12 hypovolemic shock patients treated with centhaquine who participated in an open-label phase IV study (NCT05956418). Echocardiography was utilized to measure stroke volume (SV), cardiac output (CO), left ventricular outflow tract velocity time integral (LVOT-VTI) and diameter (LVOTd), heart rate (HR), left ventricular ejection fraction (LVEF) and fractional shortening (LVFS), and inferior vena cava (IVC) diameter before (0 min) and 60, 120, and 300 min after centhaquine (0.01 mg/kg) iv infusion for 60 min. Results: SV was significantly increased after 60, 120, and 300 min. CO increased significantly after 120 and 300 min despite a decrease in HR. IVC diameter and LVOT-VTI at these time points significantly increased, indicating the increased venous return. LVEF and LVFS did not change, while the mean arterial pressure (MAP, mmHg) increased after 120 and 300 min. Positive correlations between IVC diameter and SV (R2 = 0.9556) and between IVC diameter and MAP (R2 = 0.8928) were observed, which indicated the effects of an increase in venous return on SV, CO, and MAP. Conclusions: Centhaquine-mediated increase in venous return is critical in enhancing SV, CO, and MAP in patients with hypovolemic shock; these changes could be pivotal for reducing shock-mediated circulatory failure, promoting tissue perfusion, and improving patient outcomes. Trial Registration: CTRI/2021/01/030263 and NCT05956418.

The exploration of perioperative hypotension subtypes: a prospective, single cohort, observational pilot study.

Background: Hypotension is a risk factor for postoperative complications, but evidence from randomized trials does not support that a higher blood pressure target always leads to optimized outcomes. The heterogeneity of underlying hemodynamics during hypotension may contribute to these contradictory results. Exploring the subtypes of hypotension can enable optimal management of intraoperative hypotension. Methods: This is a prospective, observational pilot study. Patients who were ≥ 45 years old and scheduled to undergo moderate-to-high-risk noncardiac surgery were enrolled in this study. The primary objective of this pilot study was to investigate the frequency and distribution of perioperative hypotension and its subtypes (hypotension with or without cardiac output reduction). The exposure of hypotension and its subtypes in patients with and without myocardial or acute kidney injury were also explored. Results: Sixty patients were included in the analysis. 83% (50/60) of the patients experienced perioperative hypotension. The median duration of hypotension for each patient was 8.0 [interquartile range, 3.1-23.3] minutes. Reduced cardiac output was present during 77% of the hypotension duration. Patients suffering from postoperative myocardial or acute kidney injury displayed longer duration and more extensive exposure in all hypotension subtypes. However, the percentage of different hypotension subtypes did not differ in patients with or without postoperative myocardial or acute kidney injury. Conclusion: Perioperative hypotension was frequently accompanied by cardiac output reduction in moderate-to-high-risk noncardiac surgical patients. However, due to the pilot nature of this study, the relationship between hypotension subtypes and postoperative myocardial or acute kidney injury still needs further exploration. Clinical trial registration: https://www.chictr.org.cn/showprojEN.html?proj=134260, CTR2200055929.

Cardiac-output response to exercise after allogeneic hematopoietic stem cell transplantation: a case report with a 2-year follow-up.

Cardiac-output response to exercise was evaluated over a 2-year period in hematopoietic stem cell transplant recipients treated with cardiotoxic drugs. During the study period, resting cardiac function was normal; however, the cardiac output response to exercise decreased, and an association with exercise tolerance was observed. Regular assessments of cardiopulmonary function and exercise guidance are vital for patients at high risk of cancer therapy-related cardiac dysfunction, in line with the principles of cardiac oncology rehabilitation.

Vasoconstriction with phenylephrine increases cardiac output in preload dependent patients.

General Anaesthesia (GA) is accompanied by a marked decrease in sympathetic outflow and thus loss of vasomotor control of cardiac preload. The use of vasoconstriction during GA has mainly focused on maintaining blood pressure. Phenylephrine (PE) is a pure α1-agonist without inotropic effects widely used to correct intraoperative hypotension. The potential of PE for augmenting cardiac stroke volume (SV) and -output (CO) by venous recruitment is controversial and no human studies have explored the effects of PE in preload dependent circulation using indicator dilution technique. We hypothesized that PE-infusion in patients with cardiac stroke volume limited by reduced preload would restore preload and thus augment SV and CO. 20 patients undergoing GA for gastrointestinal surgery were monitored with arterial catheter and LiDCO unity monitor. Upon stable haemodynamics after induction patients were placed in head-up tilt (HUT). All patients became preload responsive as verified by a stroke volume variation (SVV) of > 12%. PE-infusion was then started at 15-20mikrg/min and adjusted until preload was restored (SVV < 12%). Li-dilution cardiac output (CO) was initially measured after induction (baseline), again with HUT in the preload responsive phase, and finally when preload was restored with infusion of PE.At baseline SVV was 10 ± 3% (mean ± st.dev.), CI was 2,6 ± 0,4 L/min*m2, and SVI 43 ± 7mL/m2. With HUT SVV was 19 ± 4%, CI was 2,2 ± 0,4 L/min*m2, SVI 35 ± 7mL/m2. During PE-infusion SVV was reduced to 6 ± 3%, CI increased to 2,6 ± 0,5 L/min*m2, and SVI increased to 49 ± 11mL/m2. All differences p < 0,001. In conclusion: Infusion of phenylephrine during preload dependency increased venous return abolishing preload dependency as evaluated by SVV and increased cardiac stroke volume and -output as measured by indicator-dilution technique. (ClinicalTrials.gov NCT05193097).

Evaluation of the Effect of Conversion of Nonvalvular Atrial Fibrillation to Sinus Rhythm on Cardiac Remodeling.

BACKGROUND: Atrial fibrillation (AF) represents the most prevalent cardiac arrhythmia globally, with a significant burden on mortality and morbidity. While rhythm control strategies, particularly electrical cardioversion (EC), have gained traction in recent years, the precise impact of sinus rhythm (SR) restoration on cardiac reverse remodeling remains a subject of debate. METHODS: In this study, 23 AF patients underwent elective EC. AF diagnosis was made via ECG by a cardiologist, and candidates for cardioversion were selected by an electrophysiologist. Transthoracic echocardiography (TTE) by utilizing two-dimensional, three-dimensional, and tissue Doppler imaging modalities was performed before cardioversion. Patients who maintained SR after six months underwent a second TTE evaluation. RESULTS: SR was restored successfully in all 23 patients and 15 patients (65.2%) maintained SR after six months. SR group had significantly lower baseline cardiac output (CO) and indexed left ventricular end-systolic volume (LVESVi), and better European Heart Rhythm Association (EHRA) scores after six months. Within the SR group, patients exhibited significant changes in mitral regurgitation, tricuspid regurgitation, EHRA score, LVESVi, stroke volume, left ventricle ejection fraction, left ventricle global longitudinal strain, indexed minimum left atrial volume, left atrial emptying fraction, and left and right atrial diameters. Reduced CO was associated with AF recurrence. Receiver operating curve analysis revealed that CO value can predict six-month AF recurrence with a cut-off point of 2.3. CONCLUSION: Our study underscores the beneficial effects of SR restoration on cardiac parameters in AF patients post EC. Notably, CO value emerged as a predictor of AF recurrence, emphasizing the importance of comprehensive assessments for predicting long-term outcomes.

Echocardiographic derived forward left ventricular output improves risk prediction in systolic heart failure.

BACKGROUND AND AIMS: Though widely used to classify heart failure (HF) patients, the prognostic role of left ventricular ejection fraction (LVEF) is debated. We hypothesized that the echocardiographic measures of forward LV output, being more representative of cardiac hemodynamics, may improve risk prediction in a large cohort of HF patients with systolic dysfunction. METHODS: Consecutive stable HF patients with LVEF <50% on guideline-recommended therapies undergoing an echocardiography including the evaluation of forward LV output (i.e., LV outflow tract velocity-time integral [LVOT-VTI], stroke volume index [SVi], and cardiac index [CI]) over a 6-year period, were selected and followed-up for the endpoint of cardiac and all-cause death. RESULTS: Among the 1,509 patients analyzed (71±12 years, 75% males, LVEF 35±9%), 328 (22%) died during a median 28-month (14-40) follow-up, 165 (11%) of which for cardiac causes. At multivariable regression analysis, LVOT-VTI (<0.001), SVi (p<0.001), and CI (p<0.001), but not LVEF (p>0.05), predicted cardiac and all-cause death. The optimal prognostic cut-offs for LVOT-VTI, SVi, and CI were 15 cm, 38 mL/m2, and 2 L/min/m2, respectively. Adding each of these measures to a multivariable risk model (including clinical, biohumoral, and echocardiographic markers) improved risk prediction (p<0.001). Among the different measures of forward LV output, CI was less accurate than LVOT-VTI and SVi. CONCLUSION: The echocardiographic evaluation of forward LV output improves risk prediction in HF patients across a wide LVEF spectrum over other well-established clinical, biohumoral, and echocardiographic prognostic markers.

Norepinephrine or phenylephrine for the prevention of post-spinal hypotension after caesarean section: A double-blinded, randomized, controlled study of fetal heart rate and fetal cardiac output.

STUDY OBJECTIVE: Spinal anesthesia often causes hypotension, with consequent risk to the fetus. The use of vasopressor agents has been highly recommended for the prevention of spinal anesthesia-induced hypotension during caesarean delivery. Many studies have shown that norepinephrine can provide more stable maternal hemodynamics than phenylephrine. We therefore tested the hypothesis that norepinephrine preserves fetal circulation better than phenylephrine when used to treat maternal hypotension consequent to spinal anesthesia. DESIGN: Prospective, randomized, double-blinded study. SETTING: Operating room. PATIENTS: We recruited 223 parturients with uncomplicated singleton pregnancies who were scheduled for elective caesarean section under combined spinal-epidural anesthesia. INTERVENTIONS: The patients received prophylactic intravenous infusion of either 0.08 µg/kg/min norepinephrine or 0.5 µg/kg/min phenylephrine for prevention of spinal anesthesia-induced hypotension. MEASUREMENTS: Changes in fetal heart rate and fetal cardiac output before and after spinal anesthesia were measured using noninvasive Doppler ultrasound. MAIN RESULTS: 90 subjects who received norepinephrine infusion and 93 subjects who received phenylephrine infusion were ultimately analyzed in the present study. The effects of norepinephrine and phenylephrine on the change of fetal heart rate and fetal cardiac output at 3 and 6 min after spinal block were similar. Although there was a statistically significant decrease in fetal cardiac output at 6 min after subarachnoid block initiation in both the norepinephrine group (mean difference 0.02 L/min; 95% CI, 0-0.04 L/min; P = 0.03) and the phenylephrine group (mean difference 0.02 L/min; 95% CI, 0-0.04 L/min; P = 0.02), it remained within the normal range. CONCLUSIONS: Prophylactic infusion of comparable doses of phenylephrine or norepinephrine has similar effects on fetal heart rate and cardiac output changes after spinal anesthesia. Neither phenylephrine nor norepinephrine has meaningful detrimental effects on fetal circulation or neonatal outcomes.

Individualising goal-directed haemodynamic therapy: future iterations will require novel trial designs.

Variants of perioperative cardiac output-guided haemodynamic therapy algorithms have been tested over the last few decades, without clear evidence of effectiveness. Newer approaches have focussed on individualisation of physiological targets and have been tested in early efficacy trials. Uncertainty about the benefits remains. Adoption of novel trial designs could overcome the limitations of smaller trials of this complex intervention and accelerate the exploration of future developments.

Acute Effects of Skeletal Muscle Electrical Stimulation on Central and Lower Extremity Hemodynamics.

INTRODUCTION: Belt electrode-skeletal muscle electrical stimulation (B-SES) is a treatment prescribed for individuals with difficulty performing exercise therapy that improves muscle strength, exercise tolerance, and glucose metabolism. However, the effects of B-SES on the hemodynamics of the central and lower extremity conduit arteries have not been studied. Therefore, this study compared the acute effects of B-SES on the central and lower extremity conduit arteries in healthy young males. METHODS: This randomized crossover study included nine healthy young males (mean age: 21.0±1.1 years). Participants were assigned to the following experimental conditions, with a washout period of one week: condition 1 included 20 min of electrical stimulation of the lower extremity at the participant's sensation threshold intensity (Sham, n=9) and condition 2 included 20 min of electrical stimulation of the lower extremity at the maximum intensity the participant can tolerate (B-SES, n=9). The heart rate (HR), stroke volume (SV), cardiac output (CO), mean arterial pressure (MAP), and total peripheral vascular resistance (TPR) were measured as central hemodynamics. The hemodynamics of the lower extremity conduit arteries were measured and calculated for the shallow femoral artery (SFA), including vessel diameter, mean blood flow velocity (MBFV), shear rate (SR), and mean blood flow (MBF) rate. These indices were measured before stimulation (Pre), 10 min after the start of stimulation (Stimulating), and immediately after the end of stimulation (Post). These indices were compared using a repeated two-way analysis of variance. RESULTS: In B-SES, HR (Pre: 63.2±8.6; Stimulating: 73.7±6.9; Post: 70.0±4.2 bpm, p<0.01), CO (Pre: 5.1±1.0; Stimulating: 6.5±1.5, p<0.01; Post: 6.3±1.2 L/min, p=0.02), and MAP (Pre: 104.0±11.5; Stimulating: 116.4±10.8, p<0.01; Post: 109.6±9.7 mmHg, p=0.02) increased significantly. In addition, B-SES significantly increased MBFV (Pre: 19.2±4.0; Stimulating: 50.5±14.9; Post: 30.1±4.0 cm/s, p<0.01), SR (Pre: 118.9±28.8; Stimulating: 302.7±91. 2, p<0.01; Post: 182.1±70.1/s, p=0.02), and MBF (Pre: 382.0±61.5; Stimulating: 1009.6±321.4; Post: 626.8±176.6 mL/min, p<0.01). However, there were no significant changes in SV and TPR. CONCLUSIONS: The findings of this study indicate that B-SES in healthy young males increases CO without increasing SV or TPR and improves the MBFV and SR in the SFA.

Effects of exercise training on cardiac output in subjects with heart failure with preserved ejection fraction (HFpEF) - a protocol for a systematic review and meta-analysis.

BACKGROUND: Patients with heart failure with preserved ejection fraction (HFpEF) commonly experience exercise intolerance, resulting in reduced cardiorespiratory fitness. This is characterised by a decreased maximal oxygen uptake (V̇O2peak), which is determined by the product of cardiac output (CO) and arteriovenous oxygen difference (a-vDO2). While exercise training has been shown to improve V̇O2peak in HFpEF patients, the effects on CO remain unclear. The aim of this study is to systematically review and analyse the current evidence on the effects of supervised exercise training on CO in patients with HFpEF. METHODS: We will systematically search for literature describing the effects of supervised exercise training on CO in patients with HFpEF. All eligible studies published before 30 June 2023 in the following electronic databases will be included: MEDLINE (Ovid), Embase (Ovid), SPORTDiscus (EBSCOhost), and CENTRAL (Cochrane Library). Effect sizes will be extracted for CO before and after a supervised exercise training intervention at rest and maximal exercise. Mass of heterogeneity (I2) will be calculated, and either fixed-effect models or random-effect models will be used for meta-analysis. To detect a potential publication bias, funnel plot analyses will be performed. DISCUSSION: While several studies have reported a positive effect of supervised exercise training on cardiorespiratory fitness, attempts to assess the underlying determinants of V̇O2peak, CO, and a-vDO2 are much scarcer, especially in patients with HFpEF. From a physiological perspective, measuring CO before and after supervised exercise training seems to be a reasonable way to accurately operationalise a potential improvement in cardiac function. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42022361485.

The effect of restrictive compared to liberal intravenous fluid volume on hypotension in adults undergoing major abdominal surgery.

In a cardiac output (CO) sub-study of the Restrictive versus Liberal Fluid Therapy in Major Abdominal Surgery (RELIEF) trial, it was shown that restrictive fluid management was associated with lower cardiac index at the end of surgery. However, the association of the fluid protocol with intraoperative blood pressure was less clear. This paper primarily compares rates of hypotension between the two fluid regimens. The haemodynamic effects of these protocols may increase our understanding of perioperative fluid prescription. Using a data set of arterial pressure and cardiac output measurements, this observational cohort study primarily compares intraoperative hypotension rates defined by a mean arterial pressure < 65 mmHg between liberal and restrictive fluid protocols. Secondary analyses explore predictors of invasive mean arterial pressure and doppler-derived cardiac output, including fluid volume regimens and surgical duration. 105 patients had a combined total of 835 haemodynamic data capture events from the beginning to the end of the surgery. Here we report that a restrictive regimen is not associated with a greater proportion of participants who experience at least one episode of hypotension than the liberal regimen 64.1% vs. 61.5% (mean difference 2.6%, 95% CI - 15.9% to 21%, p = 0.78). Duration of surgery was associated with an increased risk of hypotension (OR 1.05, 1 to 1.1, p = 0.038). A fluid restriction protocol compared to liberal fluid administration is not associated with lower blood pressure.

The Utility of Echocardiography in Estimating Fluid Responsiveness.

Assessing the volume status in critically ill patients is the key to maintain the stability of the hemodynamics; however, it can be challenging to view the complexity of cases and the diversity of shock etiology. Multiple noninvasive means have been used to study the effectiveness of volume resuscitation, but none of them have been used as gold standard. We aim to illustrate the most used techniques: left ventricular outflow tract velocity time integral versus inferior vena cava compressibility index, and highlight their limitations and strengths. These tools are both operator-dependent and might be affected by several factors including ventilator settings.

Maternal vascular indices at 36 weeks' gestation in small and growth restricted fetuses.

OBJECTIVE: To compare maternal vascular indices and hemodynamic parameters at 35-37 weeks' gestation, in pregnancies complicated by small for gestational age (SGA) fetuses and those with fetal growth restriction (FGR). METHODS: This was a prospective observational non-intervention study in women with singleton pregnancies attending for a routine hospital visit at 35+0 to 36+6 weeks' gestation. The visit included recording of maternal demographic characteristics and medical history, vascular indices and hemodynamic parameters obtained by a non-invasive operator independent device, including pulse wave velocity, augmention index, cardiac output, stroke volume, central systolic and diastolic blood pressure, total peripheral resistance and fetal heart rate. Hypertensive disorders of pregnancy were excluded and the values in the SGA and FGR groups were compared between them and with unaffected pregnancies. Diagnosis of SGA was based on the birth of a baby with birthweight below the 10th percentile for gestational age. In FGR, in addition to a birthweight below the 10th percentile, at the 35-37 weeks scan Doppler studies had shown that the uterine artery or umbilical artery pulsatility index (PI) was above the 95th percentile for gestational age or the fetal middle cerebral artery PI was below the 5th percentile. RESULTS: In the 6,413 women included in the study there were 605 (9.4%) cases of SGA, 133 (2.1%) of FGR and 5,675 (88.5%) unaffected by SGA or FGR. Women with SGA or FGR, compared to unaffected pregnancies, had increased peripheral vascular resistance and reduced cardiac output. Central systolic and diastolic blood pressure were also increased, whereas aortic stiffness assessed by pulse wave velocity and augmentation index did not differ between affected and unaffected pregnancies. In the FGR, compared to the SGA group, central systolic and diastolic blood pressure were higher, whereas, heart rate was lower. CONCLUSIONS: In SGA and FGR pregnancies there are deranged maternal hemodynamic responses when these are compared to normal pregnancies. Mothers with FGR babies have higher central blood pressure compared to SGA ones, but it remains unclear whether these differences are driven by the size of the fetus or pathological fetal growth. This article is protected by copyright. All rights reserved.

Cardiac output calculation using the Liljestrand and Zander formula: is this method applicable during immediate transition after birth? - A post hoc analysis.

The transition from intrauterine to extrauterine life is a critical period for neonates. Assessing the cardiovascular transition during this period immediately after birth is crucial but challenging. The present study compares adjusted estimated cardiac output values calculated by the Liljestrand and Zander formula (COest/adj LaZ) with non-invasively measured cardiac output values (CO-bioimpedance) during immediate transition after birth. We performed a secondary outcome analysis of a prospective observational study in preterm and term neonates. Ten and 15 min after birth, arterial blood pressure and heart rate were assessed, and CO-bioimpedance was measured using electrical bioimpedance method (Aesculon monitor, Osypka, Germany). We calculated COest/adj LaZ and compared it to CO-bioimpedance. Further, we performed a correlation analysis. Thirty-two neonates with a median (IQR) gestational age of 37.0 (32.0-39.4) weeks were included. Mean ± SD CO-bioimpedance was 0.62 ± 0.15 l/min, and COest/adj LaZ was calculated to be 0.64 ± 0.10 l/min, whereby both correlated significantly (p = 0.025, r = 0.359) with each other.  Conclusion: The present study demonstrates high comparability of COest/adj LaZ and CO-bioimpedance in neonates during immediate transition after birth, suggesting that cardiac output can be derived in a cost-effective and feasible manner if other methods are not available. What is Known: • Echocardiography is considered the gold standard for non-invasive CO evaluation, but its feasibility during the immediate transition period is limited. What is New: • Non-invasive methods such as CO-bioimpedance for cardiac output (CO) measurement and the Liljestrand and Zander (LaZ) formula for estimating CO offer promising alternatives during the immediate transition period.

Early postoperative beta-blockers are associated with improved cardiac output after late complete repair of tetralogy of Fallot: a retrospective cohort study.

Tetralogy of Fallot is the most common cyanotic congenital heart disease. For decades, our institution has cared for humanitarian patients with late presentation of tetralogy of Fallot. They are characterized by severe right ventricular hypertrophy with consecutive diastolic dysfunction, increasing the risk of postoperative low cardiac output syndrome (LCOS). By right ventricular restrictive physiology, we hypothesized that patients receiving early postoperative beta-blockers (within 48 h after cardiopulmonary bypass) may have better diastolic function and cardiac output. This is a retrospective cohort study in a single-center tertiary pediatric intensive care unit. We included > 1-year-old humanitarian patients with a confirmed diagnosis of tetralogy of Fallot undergoing a complete surgical repair between 2005 and 2019. We measured demographic data, preoperative echocardiographic and cardiac catheterization measures, postoperative mean heart rate, vasoactive-inotropic scores, LCOS scores, length of stay, and mechanical ventilation duration. One hundred sixty-five patients met the inclusion criteria. Fifty-nine patients (36%) received early postoperative beta-blockers, associated with a lower mean heart rate, higher vasoactive-inotropic scores, and lower LCOS scores during the first 48 h following cardiopulmonary bypass. There was no significant difference in lengths of stay and ventilation. Conclusion: Early postoperative beta-blockers lower the prevalence of postoperative LCOS at the expense of a higher need for vasoactive drugs without any consequence on length of stay and ventilation duration. This approach may benefit the specific population of children undergoing a late complete repair of tetralogy of Fallot. What is Known: • Prevalence of low cardiac output syndrome is high following a late complete surgical repair of tetralogy of Fallot. What is New: • Early postoperative beta-blockade is associated with lower heart rate, prolonged relaxation time, and lower prevalence of low cardiac output syndrome. • Negative chronotropic agents like beta-blockers may benefit selected patients undergoing a late complete repair of tetralogy of Fallot, who are numerous in low-income countries.

Heat-related changes in the velocity and kinetic energy of flowing blood influence the human heart's output during hyperthermia.

Passive whole-body hyperthermia increases limb blood flow and cardiac output ( Q ̇ $\dot Q$ ), but the interplay between peripheral and central thermo-haemodynamic mechanisms remains unclear. Here we tested the hypothesis that local hyperthermia-induced alterations in peripheral blood flow and blood kinetic energy modulate flow to the heart and Q ̇ $\dot Q$ . Body temperatures, regional (leg, arm, head) and systemic haemodynamics, and left ventricular (LV) volumes and functions were assessed in eight healthy males during: (1) 3 h control (normothermic condition); (2) 3 h of single-leg heating; (3) 3 h of two-leg heating; and (4) 2.5 h of whole-body heating. Leg, forearm, and extracranial blood flow increased in close association with local rises in temperature while brain perfusion remained unchanged. Increases in blood velocity with small to no changes in the conduit artery diameter underpinned the augmented limb and extracranial perfusion. In all heating conditions, Q ̇ $\dot Q$ increased in association with proportional elevations in systemic vascular conductance, related to enhanced blood flow, blood velocity, vascular conductance and kinetic energy in the limbs and head (all R2 ≥ 0.803; P < 0.001), but not in the brain. LV systolic (end-systolic elastance and twist) and diastolic functional profiles (untwisting rate), pulmonary ventilation and systemic aerobic metabolism were only altered in whole-body heating. These findings substantiate the idea that local hyperthermia-induced selective alterations in peripheral blood flow modulate the magnitude of flow to the heart and Q ̇ $\dot Q$ through changes in blood velocity and kinetic energy. Localised heat-activated events in the peripheral circulation therefore affect the human heart's output. KEY POINTS: Local and whole-body hyperthermia increases limb and systemic perfusion, but the underlying peripheral and central heat-sensitive mechanisms are not fully established. Here we investigated the regional (leg, arm and head) and systemic haemodynamics (cardiac output: Q ̇ $\dot Q$ ) during passive single-leg, two-leg and whole-body hyperthermia to determine the contribution of peripheral and central thermosensitive factors in the control of human circulation. Single-leg, two-leg, and whole-body hyperthermia induced graded increases in leg blood flow and Q ̇ $\dot Q$ . Brain blood flow, however, remained unchanged in all conditions. Ventilation, extracranial blood flow and cardiac systolic and diastolic functions only increased during whole-body hyperthermia. The augmented Q ̇ $\dot Q$ with hyperthermia was tightly related to increased limb and head blood velocity, flow and kinetic energy. The findings indicate that local thermosensitive mechanisms modulate regional blood velocity, flow and kinetic energy, thereby controlling the magnitude of flow to the heart and thus the coupling of peripheral and central circulation during hyperthermia.

Right heart catheterization in idiopathic pulmonary hypertension: An all-inclusive necessity.

The gold standard for diagnosis of pulmonary hypertension is right heart catheterization. This procedure requires considerable expertise and has its own procedure related complications. If not done properly, it can lead to misinterpretations of its findings. We have highlighted the procedural technique and major pitfalls in the diagnosis of pulmonary hypertension.