High Cardiac Output Research Articles

Abstract 13977: Identification of Intermediate Right Ventricular Phenotypes Using Consensus Clustering in Patients With Pulmonary Hypertension

Introduction: Current right ventricular (RV) function phenotypes in pulmonary hypertension (PH) rely on few hemodynamic parameters to quantify RV dysfunction disease severity. The aim of the study was to identify novel RV phenotypes using RV hemodynamics and unsupervised machine learning in patients with PH. Methods: Participants were identified from the UArizona PH Registry (n=190). Correlation analyses identified 9 RV variables to include in clustering analysis. Consensus clustering was used to identify an unsupervised clustering method with a large inter-cluster, and small intra-cluster distance (Fig 1A). Significance was tested with Dunn and chi-square tests. Results: K-Medoids with a Pearson distance matrix over >1000 resampling iterations identified 5 clusters (consensus range: 0.8-0.9). World Symposium PH groups were distributed across clusters (Fig 1B). Clusters 1, 2 and 5 exhibit mild RV dysfunction with low diastolic stiffness (Eed) and afterload (Ea, Fig 1C). However, RV-PA coupling (Ees/Ea) was decreased in clusters 1 and 5. Clusters 3 and 4 have moderate to severe RV dysfunction with increased Eed and Ea but cluster 4 had decreased Ees/Ea. For pulmonary hemodynamics, clusters 3 and 4 have increased mean PA pressure (mPAP), increased pulmonary vascular resistance (PVR) and decreased PA compliance (Ca) compared to clusters 1 and 2. Cluster 5 has increased mPAP and high cardiac output resulting in moderately elevated PVR and decreased Ca. Conclusions: Unsupervised clustering identified 5 unique RV phenotypes ranging from mild to severe dysfunction. Further investigations are needed to identify factors modulating intermediate phenotypes to provide insight into RV dysfunction and disease progression.

Early Results Using N-Terminal pro-B-Type Natriuretic Peptide (pro-BNP) as a Biomarker for the Efficacy of Secondary Extension Technique (SET) in Improving Myocardial Function in Dialysis Patients With High Flow Fistulas

The association of dialysis fistulas and heart failure is believed to be due to high cardiac output. N-terminal pro-B-Type Natriuretic Peptide (pro-BNP) which is secreted by the cardiac ventricles in response to excessive stretching of the myocytes has been used as a marker of heart failure with 90% sensitivity. We report our early experience using pro-BNP levels to test the efficacy of the novel 'secondary extension technique' (SET) in improving myocardial function by reducing fistula flow. Eleven patients with high fistula flows (>3000 mL/m, all brachio-cephalic) and raised pro-BNP underwent SET between 2011 and 2015. SET involves extending the anastomosis from brachial to either proximal radial or ulnar arteries. We measured pro-BNP levels, fistula flow and clinical improvements both pre and post operatively. SET resulted in a median (IQR) flow rate decrease of 57.9 (11.9)% which correlated with a fall in pro-BNP of 69.6 (39)%. Seven of the 11 patients in the series pro-BNP level returned to a normal value at average follow-up of 3 months post SET. All patients had HOF-related symptom resolution post-procedure and remained asymptomatic at last follow-up CONCLUSIONS: Our pilot data suggests that SET is an effective way of reducing fistula flow. It also shows that BNP may be a reliable biomarker in assessing the impact of the technique on cardiac function. These results warrant further investigation in the form of a definitive, multicenter study.

52-Year-Old Woman With Palpitations, Abdominal Distension, and Severe Abdominal Pain

52-Year-Old Woman With Palpitations, Abdominal Distension, and Severe Abdominal Pain

581 Renal Arteriovenous Fistula Percutaneous Embolization Using the Amplatzer Vascular Plug II

Abstract Introduction Renal arteriovenous fistula (AVF) is not considered a common condition; however, it can occasionally complicate with renal impairment and heart failure secondary to high cardiac output. Recently, percutaneous embolization has overcome traditional surgery as the first line of its management, because of better success rates as well as less morbidity and mortality. Case report A 68-year-old male who presented with a renal AVF post left partial nephrectomy associated with a large pseudoaneurysm. This was found on a computed tomography angiography (CTA) scan, a routine follows up for his endovascular aortic aneurysm repair. Due to the patient’s co-morbidities and to avoid the potentially fatal pseudoaneurysm rupture, a minimal invasive approach was agreed in the multidisciplinary meeting. He was treated by percutaneous transcatheter embolization using the Amplatzer Vascular Plug II (AVP-II) through a right femoral arterial access. The patient recovery was uneventful, following an overnight stay he was discharged home. CTA done four and ten months later showed the AVP-II device inside the left renal artery branch feeder with no artifacts seen. There was absence of recanalization of the AVF. In the literature, adopting the transarterial route for the renal AVF treatment with AVP-II device as a single embolotherapy device has not been reported before. Conclusions Our report display the feasibleness of AVP-II in renal AVF treatment by arterial feeder embolization, specifically in fistulas with high flow and short communication as our case in which it showed offered multiple advantages over coils and is more cost effective.

Carbon Dioxide Elimination After Sodium Bicarbonate Administration as a Novel Method to Assess Cardiac Output: A Pilot Study.

IntroductionCardiac output/pulmonary blood flow measurement is an important way to assess patients during the perioperative period, as well as patients who are critically ill. Current methods of assessing cardiac output have limitations. One indicator of cardiac output may be the expired carbon dioxide (CO2) partial pressure response to intravenous sodium bicarbonate (IVSB), which is rapidly converted to CO2.MethodsWe conducted an initial evaluation of the relationship between expired CO2 partial pressure and blood flow after a bolus of IVSB. To assess this relationship, we used a cardiopulmonary bypass circuit with predetermined blood flows in a laboratory trial and then assessed 18 patients undergoing surgery requiring cardiopulmonary bypass.ResultsFor the laboratory portion of this pilot study, higher peak expired CO2, faster time to reach peak, higher area under the curve, and greater kurtosis of peak were observed at higher cardiac output flow rates, and higher mean expired CO2 was significantly associated with higher flow rates (p < 0.001). In the human study, higher mean (p = 0.023) and peak expired CO2 (p = 0.028) were both significantly associated with higher cardiac output flow rates.ConclusionsThis technique may be a way to intermittently assess cardiac output or improve accuracy when used in conjunction with other continuous output monitors.

Effects of Performing Applied Muscle Tension during Recovery after Phlebotomy in Young, First-Time Donors: A Pilot Study.

Vasovagal reaction (VVR) compromises donor safety and reduces the subsequent return rates. Performing applied muscle tension (AMT) during phlebotomy may reduce the incidence of VVR. However, the effectiveness of performing AMT after phlebotomy to reduce delayed VVR remains unclear. With ethics approval, 12 young, first-time donors (YFTD) were recruited to study the effects on stroke volume (SV), cardiac output (CO) and systemic vascular resistance (SVR) while performing AMT from needle insertion to end of recovery. Measurements from 12 matched control YFTD were used for comparison. Pre-donation anxiety and VVR severity were assessed. Compared to controls, donors who performed AMT had higher SV (Control: 57 mL vs. AMT: 69 mL, p = 0.045), higher CO (Control: 3.7 L·min−1 vs. AMT: 5.2 L·min−1, p = 0.006) and lower SVR (Control: 1962 dyn·s·cm−5 vs. AMT: 1569 dyn·s·cm−5, p = 0.032) during mid-phlebotomy. During recovery, the AMT group retained higher SV, higher CO and lower SVR than the control, but not reaching statistical significance. Practicing AMT during recovery resulted in sustained haemodynamic improvements beyond the donation period, despite the reduction in delayed VVR was insignificant compared to the control group. A larger sample size is needed to validate the effectiveness of performing AMT after donation to mitigate delayed VVR.

Health-related quality of life and hospitalizations in chronic thromboembolic pulmonary hypertension versus idiopathic pulmonary arterial hypertension: an analysis from the Pulmonary Hypertension Association Registry (PHAR).

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare, morbid, potentially curable subtype of pulmonary hypertension that negatively impacts health-related quality of life (HRQoL). Little is known about differences in HRQoL and hospitalization between CTEPH patients and idiopathic pulmonary arterial hypertension (IPAH) patients. Using multivariable linear regression and mixed effects models, we examined differences in HRQoL assessed by emPHasis-10 (E10) and SF-12 between CTEPH and IPAH patients in the Pulmonary Hypertension Association Registry, a prospective multicenter cohort of patients newly evaluated at a Pulmonary Hypertension Care Center. Multivariable negative binomial regression models were used to estimate incidence rate ratios (IRR) for hospitalization amongst the two groups. We included 461 IPAH patients and 169 CTEPH patients. Twenty-one percent of CTEPH patients underwent pulmonary thromboendarterectomy (PTE) before the end of follow-up. At baseline, patients with CTEPH had significantly worse HRQoL (higher E10 scores) (ß 2.83, SE 1.11, p = 0.01); however, differences did not persist over time. CTEPH patients had higher rates of hospitalization (excluding the hospitalization for PTE) compared to IPAH patients after adjusting for age, sex, body mass index, WHO functional class and six-minute walk distance (IRR 1.66, 95%CI 1.04–2.65, p = 0.03). CTEPH patients who underwent PTE had improved HRQoL as compared to those who were medically managed, but patients who underwent PTE were younger, had higher cardiac outputs and greater six-minute walk distances. In this large, prospective, multicenter cohort, CTEPH patients had significantly worse baseline HRQoL and higher rates of hospitalizations than those with IPAH. CTEPH patients who underwent PTE had significant improvements in HRQoL.

May standard basal echocardiogram allow to obtain predictors of asymptomatic cardiac dysfunction in alcoholics?

Long-lasting heavy alcohol intake has been progressively recognized as a leading cause of nonischemic dilated cardiomyopathy, involving 10% of all people who use alcohol. It is of huge importance to identify the earliest markers of this dysfunction and it is known that the newest echocardiographic techniques such as speckle tracking may allow to do it. In this study we investigated if standard basal echocardiogram features allow to obtain predictors of asymptomatic cardiac dysfunction in alcoholics. A population of 80 consecutive asymptomatic alcoholics was enrolled. None presented history, signs or symptoms of cardiovascular disease. All of them underwent a conventional transthoracic monobidimensional and doppler echocardiography. Our cohort did not present echocardiographic findings of increased left ventricular sizes, mass or relative wall thickness. Hence, a significant rate of systolic dysfunction was not found. Furthermore, statistical analysis displayed an inverse relationship between alcohol consumption and systolic pulmonary arterial pressure as well as between alcohol abuse and left atrium enlargement. This may be explained by a potential vasodilator mechanism occurring in the earliest stages of alcohol intake. On the contrary, a positive correlation with the E/A ratio was found, and this might be ascribed to state of high cardiac output determined by alcohol abuse. There were modes sex-related differences. This study has demonstrated that standard echocardiography may allow to predict cardiac dysfunction in asymptomatic alcoholics, and sex-related differences may be identified in this regard. These data need to be confirmed by further studies involving larger population.

Circulatory trajectories after out-of-hospital cardiac arrest: a prospective cohort study

BackgroundCirculatory failure frequently occurs after out-of-hospital cardiac arrest (OHCA) and is part of post-cardiac arrest syndrome (PCAS). The aim of this study was to investigate circulatory disturbances in PCAS by assessing the circulatory trajectory during treatment in the intensive care unit (ICU).MethodsThis was a prospective single-center observational cohort study of patients after OHCA. Circulation was continuously and invasively monitored from the time of admission through the following five days. Every hour, patients were classified into one of three predefined circulatory states, yielding a longitudinal sequence of states for each patient. We used sequence analysis to describe the overall circulatory development and to identify clusters of patients with similar circulatory trajectories. We used ordered logistic regression to identify predictors for cluster membership.ResultsAmong 71 patients admitted to the ICU after OHCA during the study period, 50 were included in the study. The overall circulatory development after OHCA was two-phased. Low cardiac output (CO) and high systemic vascular resistance (SVR) characterized the initial phase, whereas high CO and low SVR characterized the later phase. Most patients were stabilized with respect to circulatory state within 72 h after cardiac arrest. We identified four clusters of circulatory trajectories. Initial shockable cardiac rhythm was associated with a favorable circulatory trajectory, whereas low base excess at admission was associated with an unfavorable circulatory trajectory.ConclusionCirculatory failure after OHCA exhibits time-dependent characteristics. We identified four distinct circulatory trajectories and their characteristics. These findings may guide clinical support for circulatory failure after OHCA.Trial registrationClinicalTrials.gov: NCT02648061

Abstract MP04: Interleukin-33 Drives Cardiac Remodeling And Alters Macrophage Polarization In Doca-salt Hypertension

Interleukin-33 (IL-33) is an alarmin critical for alternative macrophage activation and has been linked to hypertension in humans. The goal of this study was to evaluate whether IL-33 contributes to (deoxycorticosterone acetate) DOCA-salt induced cardiac remodeling and macrophage polarization. C57Bl/6J (WT, n=8) and IL33-deficient (IL-33 KO, n=8) mice underwent uninephrectomy, implantation of a DOCA pellet, and 1% NaCl supplementation of drinking water for three weeks. A control group of WT mice (n=10) underwent a sham procedure and were maintained on normal water. Systolic blood pressure measured by tail cuff showed a significant increase in WT DOCA-salt mice (128±9 mmHg; mean±SD) and IL-33 KO DOCA-salt mice (129±11) compared to WT sham (103±11). Hypertension was accompanied by significantly increased heart to body weight ratios in WT DOCA-salt (7.0±1.0 mg/g) and IL-33 KO DOCA-salt (6.8±0.6) compared to WT sham (5.3±0.3) mice. Glomerular injury was assessed by urine albumin-to-creatinine ratios, which were similarly increased in WT DOCA-salt (0.92±0.4) and IL-33 KO DOCA-salt (0.42±0.09) mice compared to WT controls (0.03±0.003). Echocardiography was performed to assess left ventricle (LV) dimensions and systolic function. IL-33 KO DOCA-salt mice exhibited a significantly higher cardiac output (22±2 mL/min) compared to WT sham (16±3) and WT DOCA-salt (15±3) mice, driven by increased stroke volume. No significant changes in heart rate or ejection fraction were observed between groups. Additionally, IL33-KO DOCA-salt mice had an increased diastolic LV internal dimension (3.2±0.2 mm) compared to WT sham (2.7±0.3) and WT DOCA-salt (2.7±0.3). DOCA-salt induced increased mRNA expression of alternative macrophage activation markers in both LV ( Chil3, Il10) and isolated peritoneal macrophages ( Arg1, Retnla, Tgfb1 ). Peritoneal macrophages deficient in IL-33 expressed less Il10 compared to WT. Cardiac fibrosis evaluated by Masson’s trichrome showed a significant increase in LV collagen deposition in WT DOCA-salt mice (1.09±0.8% trichrome positive) compared to WT sham (0.43±0.3) but no increase in IL-33 KO DOCA-salt mice (0.54±0.3). In conclusion, IL-33 deficiency alters macrophage and cardiac function in the DOCA-salt model of hypertension.

Agreement of Bioreactance Cardiac Output Monitoring With Thermodilution in Healthy Standing Horses.

Bioreactance is the continuous analysis of transthoracic voltage variation in response to an applied high frequency transthoracic current and was recently introduced for non-invasive cardiac output measurement (NICOM). We evaluated NICOM compared to thermodilution (TD) in adult horses. Six healthy horses were used for this prospective, blinded, experimental study. Cardiac output (CO) measurements were performed simultaneously using TD and the bioreactance method. Different cardiac output scenarios were established using xylazine (0.5 mg/kg IV) and dobutamine (1.5–3 mcg/kg/min). Statistical analysis was performed by calculating the concordance rate, performing a regression analysis, Pearson correlation, and Bland Altman. The TD-based CO and NICOM values were highly correlated for low, normal and high CO values with an overall correlation coefficient. A 4-quadrant plot showed an 89% rate of concordance. The linear regression calculated a relationship between NICOM and TDCO of Y = 0.4874 · X + 0.5936. For the corrected Bland Altman agreement, the mean bias and lower/upper limits of agreement were −0.26 and −3.88 to 3.41 L/min, respectively. Compared to TD, bioreactance- based NICOM showed good accuracy at induced low, normal, and high CO states in normal horses. Future studies performed under more clinical conditions will show if this monitor can help to assess hemodynamic status and guide therapy in horses in ICU settings and under general anesthesia.

Pulmonary Hypertension in Chronic Kidney Disease.

There is a high prevalence of pulmonary hypertension in chronic kidney disease (CKD), with rates increasing as glomerular filtration rate declines. Pulmonary hypertension is associated with a higher risk of cardiovascular events and mortality in non-dialysis-dependent CKD stages 3 to 5, dialysis-dependent CKD, as well as kidney transplant recipients. The pathophysiology of pulmonary hypertension in CKD is multifactorial and includes higher pulmonary capillary wedge pressure caused by ischemic heart disease and cardiomyopathy, higher cardiac output caused by anemia and arteriovenous access used for hemodialysis, as well as potentially higher pulmonary vascular resistance. Treatment should focus on the underlying cause.

Effect of maternal age on cardiac adaptation in pregnancy.

To compare longitudinal maternal hemodynamic changes throughout gestation between different age groups. This was a prospective longitudinal study assessing maternal hemodynamics using a bioreactance technique at 11 + 0 to 13 + 6, 19 + 0 to 24 + 0, 30 + 0 to 34 + 0 and 35 + 0 to 37 + 0 weeks' gestation. Women were divided into four groups according to maternal age at the first visit at 11 + 0 to 13 + 6 weeks: Group 1, < 25.0 years; Group 2, 25.0-30.0 years; Group 3, 30.1-34.9 years; and Group 4, ≥ 35.0 years. A multilevel linear mixed-effects model was performed to compare the repeat measurements of hemodynamic variables, correcting for demographics, medical and obstetric history, pregnancy complications, maternal age and gestational-age window. The study population included 254 women in Group 1, 442 in Group 2, 618 in Group 3 and 475 in Group 4. Younger women (Group 1) had the highest cardiac output (CO) and lowest peripheral vascular resistance (PVR), and older women (Group 4) had the lowest CO and highest PVR throughout pregnancy. The higher CO seen in younger women was achieved through an increase in heart rate alone and not with a concomitant rise in stroke volume. Although the youngest age group demonstrated an apparently more favorable hemodynamic profile, it had the highest incidence of a small-for-gestational-age neonate. There was no significant difference between the groups in the incidence of pre-eclampsia. Age-specific differences in maternal hemodynamic adaptation do not explain the differences in the incidence of a small-for-gestational-age neonate between age groups. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Cardiac output states in patients with severe functional tricuspid regurgitation: impact on treatment success and prognosis.

To investigate whether there is evidence for distinct cardiac output (CO) based phenotypes in patients with chronic right heart failure associated with severe tricuspid regurgitation (TR) and to characterize their impact on TR treatment and outcome. A total of 132 patients underwent isolated transcatheter tricuspid valve repair (TTVR) for functional TR at two centres. Patients were clustered according to k-means clustering into low [cardiac index (CI) < 1.7 L/min/m2 ], intermediate (CI 1.7-2.6 L/min/m2 ) and high CO (CI > 2.6 L/min/m2 ) clusters. All-cause mortality and clinical characteristics during follow-up were compared among different CO clusters. Mortality rates were highest for patients in a low (24%) and high CO state (42%, log-rank P < 0.001). High CO state patients were characterized by larger inferior vena cava diameters (P=0.003), reduced liver function, higher incidence of ascites (P=0.006) and markedly reduced systemic vascular resistance (P < 0.001) as compared to TTVR patients in other CO states. Despite comparable procedural success rates, the extent of changes in right atrial pressures (P=0.01) and right ventricular dimensions (P < 0.001) per decrease in regurgitant volume following TTVR was less pronounced in high CO state patients as compared to other CO states. Successful TTVR was associated with the smallest prognostic benefit among low and high CO state patients. Patients with chronic right heart failure and severe TR display distinct CO states. The high CO state is characterized by advanced congestive hepatopathy, a substantial decrease in peripheral vascular tone, a lack of response of central venous pressures to TR reduction, and worse prognosis. These data are relevant to the pathophysiological understanding and management of this important clinical syndrome.

Cardiovascular phenotypes predict clinical outcomes in sickle cell disease: An echocardiography-based cluster analysis.

This study sought to link cardiac phenotypes in homozygous Sickle Cell Disease (SCD) patients with clinical profiles and outcomes using cluster analysis. We analyzed data of 379 patients included in the French Etendard Cohort. A cluster analyses was performed based on echocardiographic variables, and the association between clusters, clinical profiles and outcomes was assessed. Three clusters were identified. Cluster 1 (n=123) patients had the lowest cardiac output, mild left cardiac cavities remodeling, mild diastolic dysfunction, and higher tricuspid regurgitation velocity (TRV). They were predominantly female and displayed the most altered functional limitation. Cluster 2 (n=102) patients had the highest cardiac output and the most remodeled cardiac cavities. Diastolic function and TRV were similar to cluster 1. These patients had a higher blood pressure and a severe hemolytic anemia. Cluster 3 (n=154) patients had mild left cardiac cavities remodeling, normal diastolic function and lowest TRV values. They were younger with the highest hemoglobin value. Right heart catheterization was performed in 94 patients. Cluster 1 (n=33) included the majority of pre-capillary PH whilst cluster 2 (n=34) included post-capillary PH. No PH was found in cluster 3 (n=27). After a follow-up of 11.4 ± 2 years, death occurred in 41 patients (11%). Cluster 2 patients had the worst prognosis with a 19% mortality rate versus 12% in cluster 1 and 5% in cluster 3 (p log-rank=0.003). Cluster analysis of echocardiography variables identified three hemodynamic and clinical phenotypes among SCD patients, each predicting a different prognosis.

The effect of acute ventilation-perfusion mismatch on respiratory heat exchange in a porcine model.

BackgroundRespiratory heat exchange is an important physiological process occurring in the upper and lower respiratory tract and is usually completed when inspired gases reach the alveoli. Animal and human studies demonstrated that heat exchange can be modulated by altering pulmonary ventilation and perfusion. The purpose of this study was to examine the effect of acute ventilation-perfusion (V/Q) mismatch on respiratory heat exchange. In clinical practice, monitoring respiratory heat exchange might offer the possibility of real-time tracking of acute V/Q-mismatch.MethodsIn 11 anesthetized, mechanically ventilated pigs, V/Q-mismatch was established by means of four interventions: single lung ventilation, high cardiac output, occlusion of the left pulmonary artery and repeated whole-lung lavage. V/Q-distributions were determined by the multiple inert gas elimination technique (MIGET). Respiratory heat exchange was measured as respiratory enthalpy using the novel, pre-commercial VQm™ monitor (development stage, Rostrum Medical Innovations, Vancouver, CA). According to MIGET, shunt perfusion of low V/Q compartments increased during single lung ventilation, high cardiac output and whole-lung lavage, whereas dead space and ventilation of high V/Q compartments increased during occlusion of the left pulmonary artery and whole-lung lavage.ResultsBohr dead space increased after pulmonary artery occlusion and whole-lung lavage, venous admixture increased during single lung ventilation and whole-lung lavage, PaO2/FiO2 was decreased during all interventions. MIGET confirmed acute V/Q-mismatch. Respiratory enthalpy did not change significantly despite significant acute V/Q-mismatch.ConclusionClinically relevant V/Q-mismatch does not impair respiratory heat exchange in the absence of additional thermal stressors and may not have clinical utility in the detection of acute changes.

Impact of a change in vascular access flow volume after percutaneous transluminal angioplasty on cardiac function.

Vascular access (VA) is necessary for patients on hemodialysis, and percutaneous transluminal angioplasty (PTA) is a useful treatment for maintaining VA function. PTA immediately increases the VA flow volume, which can affect cardiac function. We investigated the relationship between changes in VA flow volume and cardiac function in patients who underwent PTA. This was a single-center retrospective observational study, including patients who underwent PTA between June 2016 and August 2016. VA flow volume and cardiac function were measured by sonography before and 1 h after PTA. This study included 50 PTA procedures in 50 cases. PTA significantly increased the median VA flow volume from 445 (range, 150-1229) to 725 (350-1268) mL/min. Although the ejection fraction and diameter of the inferior vena cava were unchanged, the cardiac output (CO) and cardiac index increased significantly in most cases. Surprisingly, the CO was decreased in 18% of cases despite the increased VA flow volume. In this atypical group, a high CO before PTA was found to be a significant factor for the decrease in CO by PTA. In most cases, both VA flow volume and CO were increased by PTA, whereas in some cases, the CO was decreased despite an increase in VA flow volume. This atypical phenomenon may be due to the insufficient adaptive response in the peripheral artery and heart and could predict risks for future cardiac events. Therefore, it is important that such patients are carefully followed up on.

The different facets of sickle cell disease-related pulmonary hypertension

Sickle cell disease (SCD), one of the most common genetic diseases in the world, is characterized by repeated episodes of hemolysis and vaso-occlusion. Hemolytic anemia is a risk factor for the development of pulmonary hypertension, and currently SCD-related pulmonary hypertension is classified as World Health Organization group 5 pulmonary hypertension. Patients with SCD-related pulmonary hypertension have unique hemodynamics, multiple comorbidities, and distinct phenotypes that may contribute to the development of pulmonary hypertension. SCD-related pulmonary hypertension is defined as a mean pulmonary artery pressure >20 mmHg, a pulmonary artery occlusion pressure ≤15 mmHg and relatively low pulmonary vascular resistance (>2 Wood units) rather than the traditional definition of ≥3 Wood units, an important distinction due to a baseline high-cardiac output state in the setting of chronic anemia and low vascular resistance. Diastolic dysfunction is frequently identified in this patient population and right heart catheterization is essential to determine if combined pre- and postcapillary pulmonary hypertension is present. Thromboembolism is common among patients with SCD, and screening for chronic thromboembolic pulmonary hypertension is essential. Data regarding advanced therapies are limited. Primary treatment options include targeting correction of their primary hemoglobinopathy as well as aggressive management of underlying comorbid conditions. SCD-related pulmonary hypertension is common among patients with SCD and is associated with increased mortality. A high index of suspicion is warranted during evaluation to identify all potential factors that may be contributing to disease.

Effect of Exercise-Induced Reductions in Blood Volume on Cardiac Output and Oxygen Transport Capacity.

We wanted to demonstrate the relationship between blood volume, cardiac size, cardiac output and maximum oxygen uptake (O2max) and to quantify blood volume shifts during exercise and their impact on oxygen transport. Twenty-four healthy, non-smoking, heterogeneously trained male participants (27 ± 4.6 years) performed incremental cycle ergometer tests to determine O2max and changes in blood volume and cardiac output. Cardiac output was determined by an inert gas rebreathing procedure. Heart dimensions were determined by 3D echocardiography. Blood volume and hemoglobin mass were determined by using the optimized CO-rebreathing method. The O2max ranged between 47.5 and 74.1 mL⋅kg–1⋅min–1. Heart volume ranged between 7.7 and 17.9 mL⋅kg–1 and maximum cardiac output ranged between 252 and 434 mL⋅kg–1⋅min–1. The mean blood volume decreased by 8% (567 ± 187 mL, p = 0.001) until maximum exercise, leading to an increase in [Hb] by 1.3 ± 0.4 g⋅dL–1 while peripheral oxygen saturation decreased by 6.1 ± 2.4%. There were close correlations between resting blood volume and heart volume (r = 0.73, p = 0.002), maximum blood volume and maximum cardiac output (r = 0.68, p = 0.001), and maximum cardiac output and O2max (r = 0.76, p < 0.001). An increase in maximum blood volume by 1,000 mL was associated with an increase in maximum stroke volume by 25 mL and in maximum cardiac output by 3.5 L⋅min–1. In conclusion, blood volume markedly decreased until maximal exhaustion, potentially affecting the stroke volume response during exercise. Simultaneously, hemoconcentrations maintained the arterial oxygen content and compensated for the potential loss in maximum cardiac output. Therefore, a large blood volume at rest is an important factor for achieving a high cardiac output during exercise and blood volume shifts compensate for the decrease in peripheral oxygen saturation, thereby maintaining a high arteriovenous oxygen difference.

Cardiopulmonary Exercise Testing in Athletes: Expect the Unexpected.

Cardiopulmonary exercise testing (CPET) is a tool designed to assess the integrated function of the cardiac, pulmonary, vascular and musculoskeletal systems to produce an exercise effort. CPET may be performed for performance purposes as part of optimizing a training program or for clinical purposes in athletes with established cardiovascular disease or in those with symptoms suggestive of cardiopulmonary pathology. Most normative values used for CPET parameters have been derived in the general population, in whom there will be expected differences in exercise physiology as compared to a trained athlete. In this review, our goal is to examine current available data on expected findings on CPET in athletes, highlight how these differ from the general population-derived normative values, and identify areas in need of further research to optimize the application of CPET in athletes. Athletes demonstrate differences in exercise hemodynamic and gas exchange profiles as compared to non-athletes including: higher cardiac output, faster heart rate recovery, higher peak V̇O2, higher prevalence of exercise-induced arterial hypoxemia, and lower breathing reserve. CPET is an important tool to optimize performance and assess for underlying pathology in an athletic population. The impact of routine, vigorous physical activity on exercise physiology should be integrated into determination of what constitutes a normal CPET result in an athletic individual.