Outflow Tract Velocity Time Integral Research Articles

Correlation between corrected carotid flow time and left ventricular outflow tract velocity-time integral using a novel technique.

Transthoracic echocardiography (TTE) is widely used for assessing patients in the intensive care unit, with cardiac output measurement being crucial for hemodynamic monitoring. This is achieved by measuring the velocity-time integral (VTI) of the left ventricular outflow tract (LVOT), which serves as a surrogate of stroke volume. However, conducting TTE in the critical care setting presents several challenges. Our primary objective was to investigate the relationship between carotid corrected flow time (cCFT) and LVOT VTI. Additionally, we aimed to determine the threshold cCFT value that reliably predicts a normal LVOT VTI. This proof-of-concept study involves a post-hoc analysis from a diagnostic accuracy investigation conducted in a medical-surgical intensive care unit. We included patients admitted to the ICU from December 2021 to January 2022. We used a phased array transducer to measure the cCFT at the left supraclavicular fossa and the LVOT VTI in an apical 5-chamber view. We included 22 patients. The Spearman coefficient between LVOT VTI and cCFT was 0.82 (p < 0.0001). The area under the ROC curve for cCFT to predict LVOT VTI equal to or greater than 17 cm was 0.871 (95% CI 0.660-0.974). A cCFT exceeding 283 ms predicted LVOT VTI equal to or greater than 17 cm with a sensitivity of 93.3% (95% CI 68.1% to 99.8%) and specificity of 85.7% (95% CI 42.1% to 99.6%). The cCFT, measured using a novel technique with a phased array transducer, shows a strong correlation with LVOT VTI. Additionally, cCFT predicts a normal LVOT VTI with good sensitivity and specificity in critically ill patients. Larger studies are warranted to validate these findings.

Association Between Right Ventricular Systolic Parameters Measured by Echocardiography and Stroke Volume Derived From Pulmonary Artery Catheter in Ischemic Cardiogenic Shock

Objective: To determine the right ventricular (RV) systolic function echocardiographic parameter best associated with native stroke volume (SV) by thermodilution via pulmonary artery catheter (PAC) in patients admitted to intensive care with ST-elevation myocardial infarction (STEMI) complicated by cardiogenic shock (CS).Design, Setting, and Participants: Observational cohort study of 43 prospectively identified patients admitted to a tertiary cardiac intensive care unit in London, UK.Interventions: Simultaneous collection of comprehensive transthoracic echocardiographic, clinical, and PAC-derived hemodynamic data. Seven RV systolic function parameters were correlated with the PAC-derived SV.Measurements and Main Results: The median age was 61 [52, 67], and 36 patients (84%) were male. The median PAC-derived SV and LVEF were 57 ml [39, 70] and 31% [22, 35], respectively. The RV outflow tract velocity time integral (RVOT VTI) and tricuspid plane systolic excursion (TAPSE) correlated significantly with the PAC-derived SV (r = 0.42, p = 0.007, r = 0.37, p = 0.02, respectively). The RVOT VTI was independently associated with and predicted low PAC-derived SV (OR = 1.3, p = 0.03) with a good area under the curve (AUC = 0.71, p = 0.02). The RVOT VTI < 12.7 cm predicted low PAC-derived SV with a sensitivity of 66% and specificity of 72%.Conclusion: RVOT VTI is the echocardiographic RV systolic function parameter that best correlates with PAC-derived native SV in patients with STEMI complicated by CS. This parameter can help guide the hemodynamic management of this cohort.

A combination of left ventricular outflow tract velocity time integral and lung ultrasound to predict mortality in ST elevation myocardial infarction.

Development of ventricular failure and pulmonary edema is associated with a worse prognosis in ST-elevation myocardial infarction (STEMI). We aimed to evaluate the prognostic ability of a novel classification combining lung ultrasound (LUS) and left ventricular outflow tract (LVOT) velocity time integral (VTI) in patients with STEMI. LUS and LVOT-VTI were performed within 24h of admission in STEMI patients. A LUS combined with LVOT-VTI (LUV) classification was developed based on LUS with < or ≥ 3 positive zone scans, combined with LVOT-VTI > or ≤ 14. Patients were classified as A (< 3zones/ > 14cm VTI), B (≥ 3zones/ > 14cm VTI), C (< 3zones/ ≤ 14cm VTI) and D (≥ 3zones/ ≤ 14cm VTI). Primary outcome was occurrence of in-hospital mortality. Development of cardiogenic shock (CS) within 24h was also assessed. A total of 308 patients were included. Overall in-hospital mortality was 8.8%, while mortality for LUV A, B, C, and D was 0%, 3%, 12%, and 45%, respectively. The area under the curve (AUC) for predicting in-hospital mortality was 0.915. Moreover, after exclusion of patients admitted in Killip IV, at each increasing degree of LUV, a higher proportion of patients developed CS within 24h: LUV A = 0.0%, LUV B 5%, LUV C = 12.5% and LUV D = 30.8% (p < 0.0001). The AUC for predicting CS was 0.908 (p < 0.001). In a cohort of STEMI patients, LUV provided to be an excellent method for prediction of in-hospital mortality and development of CS. LUV classification is a fast, non-invasive and very user-friendly ultrasonographic evaluation method to stratify the risk of mortality and CS.

The prognostic value of right ventricular outflow tract velocity time integral in patients with pulmonary hypertension.

Right ventricular (RV) failure is one of the leading causes of death in patients with pulmonary hypertension (PH). Conventional echocardiographic parameters are not included in risk stratification and follow-up for prognostic assessment due to PH's diverse nature and the RV's complex geometry. RV outflow tract velocity time integral (RVOT VTI) is a simple, non-invasive estimate of pulmonary flow and an echocardiographic surrogate of RV stroke volume. In this study, we aimed to define the prognostic value of RVOT VTI in PH patients. Sixty-three subjects with idiopathic PAH (IPAH) (n=23), connective tissue disease-associated PAH (CTD-associated PAH) (n=19) and chronic thromboembolic pulmonary hypertension (CTEPH) (n=21) were retrospectively included. A comprehensive two-dimensional echocardiographic evaluation, including RVOT-VTI measurement, was performed during the follow-up and the New York Heart Association functional class (NYHA FC), 6min walk distance (6MWD) and brain natriuretic peptide (BNP) levels were recorded. The median age of the whole cohort was 63years (52-68), and 47 (74.6%) of the patients were women. The median follow-up period was 20months (11-33), and 20 (31.7%) patients died in this period. BNP values were higher [317 (210-641) vs 161 (47-466), P=0.02], and 6MWD values were lower [197.5±89.5 vs 339±146.3, P<0.0001] in the non-survivor group, and the non-survivor group had a worse NYHA-FC (P=0.02). Among echocardiographic data, tricuspid annular plane systolic excursion (TAPSE) (15.4±4.8 vs 18.6±4.2, P=0.01) and RVOT VTI (11.9±4.1 vs 17.2±4.3, P<0.0001) values were lower whereas right atrial area (RAA) (26.9±10.1 vs 22.2±7.1, P=0.04) values were higher in the non-survivor group. The area under curve of the RVOT VTI for predicting mortality was 0.82 [95% confidence interval (CI) 0.715-0.940, P<0.0001], and the best cut-off value was 14.7cm with a sensitivity of 80% and specificity of 77%. Survival was significantly lower in subjects with RVOT VTI≤14.7cm (log-rank P<0.0001). Survival rates for patients with RVOT VTI≤14.7cm were 70% at 1year, 50% at 2years, %29 at 3years and 21% at 5years. The univariate determinants of all-cause mortality were BNP [hazard ratio (HR) 1.001 (1.001-1.002), P=0.001], 6MWD [HR 0.994 (0.990-0.999), P=0.012] and NYHA-FC III-IV [HR 3.335 (1.103-10.083), P=0.03], TAPSE [HR 0.838 (0.775-0.929), P=0.001], RAA [HR 1.072 (1.013-1.135), P=0.016] and RVOT VTI [HR 0.819 (0.740-0.906), P<0.0001]. RVOT VTI was found to be the only independent determinant of mortality [HR 0.857 (0.766-0.960), P=0.008]. The decreased RVOT VTI predicts mortality in patients with PH and each 1mm decrease in RVOT VTI increases the risk of mortality by 14.3%. This parameter might serve as an additional parameter in the follow-up of these patients especially when 6MWD and NYHA-FC could not be determined.

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.

Low left ventricular outflow tract velocity time integral predicts normotensive shock in patients with acute pulmonary embolism

Abstract Funding Acknowledgements None. Introduction In patients with intermediate-risk acute pulmonary embolism (PE) outcomes vary widely, with mortality rates ranging from 3-15% and rates of normotensive shock up to 30%.1-3 Current risk models don't fully capture those at higher risk and identify patients who may benefit from advanced therapies. The left ventricular outflow tract (LVOT) velocity time integral (VTI), a surrogate marker of cardiac output, has been associated with increased mortality in acute PE.4 Our objective was to determine the association between LVOT VTI and its predictive value in identifying normotensive shock in this patient population. Methods Patients who underwent percutaneous mechanical thrombectomy (MT) between August 2020 and March 2023 at a large academic public hospital were considered for the study. Inclusion criteria comprised of normotensive patients (SBP ≥ 90 mmHg) with invasive measures of cardiac index (CI). VTI was obtained by pulsed wave doppler at the LVOT in either the apical 3 or apical 5 chamber view. The primary outcome was the association between LVOT VTI and normotensive shock and a cut off of 15 cm was used to examine this association based on prior studies.4 Results A total of 49 patients with intermediate-risk PE underwent MT, 16 patients had incomplete data, resulting in a final cohort of 33 patients (mean age: 57 ± 13yrs; 38% female). Patients with LVOT VTI of &amp;lt;15 cm were younger (53 vs 62 years p=0.02), had lower systolic blood pressure at presentation (122 vs 134 mmHg, p=0.047), higher heart rate (112.6 vs 96.2 beats/min, p=0.008), a higher composite shock score (CPES) (5 vs 3, p=0.012), lower cardiac index (1.9 vs 3.1 L/min/m2, p&amp;lt;0.001), a higher PASP (61.4 vs 48.9 mmHg, p=0.018), and higher rates of elevated lactate (90% vs 42%, p=0.027). LVOT VTI threshold of &amp;lt;15cm effectively identified patients with normotensive shock (90% vs 8% p&amp;lt;0.001). There was no statistically significant difference in the rates of saddle emboli, left ventricular ejection fraction, sPESI and BOVA scores in patients with VTI above or below 15cm. In patients with normotensive shock, 19/20 (95%) had LVOT VTI ≤ 15cm with a median of 13 cm (IQR 12, 14) (Figure). In patients without normotensive shock, 11/13 (84%) had LVOT VTI &amp;gt;15 with a median of 18 (IQR 17, 21). The area under the curve for LVOT VTI ≤ 15 cm in predicting normotensive shock was 0.89. The sensitivity and specificity of LVOT VTI ≤ 15 cm in predicting normotensive shock was 91.6% and 90.4% respectively. Conclusion Our study suggests that LVOT VTI is a reliable surrogate for cardiac output in patients with acute PE and can effectively identify those in the intermediate-risk group who are at risk for normotensive shock. A LVOT VTI &amp;lt;15cm may identify intermediate-risk patients at higher risk for hemodynamic decompensation and further studies are needed to evaluate whether these patients would benefit from upfront catheter-based therapies.

Risk assessment by acute bedside echocardiography prior to acute coronary angiography in patients with ST-elevation myocardial infarction: a feasibility study

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Novo Nordisk Foundation. Background Early risk assessment by hemodynamic measurements in patients with ST-elevation myocardial infarction (STEMI) could be useful for early detection of patients at risk of developing hemodynamic instability after primary percutaneous coronary intervention (pPCI). Anterior STEMI patients have larger infarct size and may be of particular interest. Transthoracic echocardiography (TTE) is a quick, non-invasive, and available tool, however, evidence regarding the use of acute TTE prior to acute coronary angiography (CAG) is limited. Purpose To assess the feasibility of acute bedside hemodynamic assessment in the cath. lab. by TTE in addition to clinical examination, and blood samples in STEMI patients without CS at arrival in the cath. lab. Methods STEMI patients without CS at hospital arrival and treated with pPCI were included in the study during a five week period. Clinical examination (Killip class), blood sampling (lactate, troponin T (TNT), proB-type natriuretic peptide (proBNP), and focused bedside 2D TTE with Doppler were performed prior to the acute CAG. The TTE protocol was focused (approx. 5 minutes) on hemodynamic measurements, infarction related complications, and differential diagnoses e.g. aortic dissection. The TTE was performed during preparation for the acute CAG. Patients were stratified in anterior- vs. non-anterior STEMI based on the culprit artery and prehospital ECG. Feasibility was estimated by all of the following echocardiographic parameters; left ventricular ejection fraction (LVEF), left ventricular outflow tract (LVOT) velocity time integral (VTI), and right ventricular function (tricuspid annular plane systolic excursion (TAPSE)). Results A total of 60 STEMI patients (aged mean 63 years, 18% female) were included, and 47% had an anterior STEMI. No differences in baseline characteristics between the two groups were found including comorbidities, clinical parameters, and time from cath. lab. arrival to first wire over the culprit lesion (median (IQR) 28 (23; 38) vs 32 (24; 40) minutes). Admission biomarkers of blood glucose, lactate, and proBNP plasma concentrations were similar between the two groups. Whereas admission TNT were higher for patients with anterior STEMI (median (IQR) 110 (37; 449) vs. 37 (20; 94) ng/L, p=0.01). The feasibility of TTE-study protocol was 93%. Patients with anterior STEMI had lower LVEF (mean: 36±11 vs. 48±9%, p=0.0003; missing: n=0), and a trend to lower LVOT VTI (19 (6.4) vs. 22 (5.0) cm, p=0.06; missing: n=4). No difference in parameters of diastolic function or TAPSE (missing: n=0) were found. None of the included patients had echocardiographic visible complications related to the infarction. Conclusion Acute TTE is to a high degree feasible and does not delay time to acute revascularization in STEMI patients. Patients with anterior STEMI have significantly higher admission TNT levels, lower LVEF, and a trend to lower LVOT VTI compared with non-anterior STEMI patients.

Association between speckle tracking echocardiography and pressure-volume loops during cardiogenic shock development

BackgroundThe relationship between speckle tracking assessed global longitudinal strain (GLS) and Doppler-based echocardiography with basic physiological markers of cardiac function derived from pressure-volume loops is poorly elucidated.ObjectiveWe aimed to describe...

Hyperosmolar Therapy in Elderly Neurosurgical Patients: Comparison of the Effect of Mannitol (20%) and Hypertonic Saline (3%) on Advanced Cardiovascular Parameters Using Transesophageal Echocardiography: A Preliminary Randomized Controlled Trial

Osmotherapeutic agents increase the intravascular volume by withdrawing water from the brain followed by relative hypovolemia due to diuresis leading to significant changes in systemic hemodynamics which might have adverse consequences in the elderly. We studied the effect of mannitol (20%) and hypertonic saline (HTS) (3%) on left ventricular outflow tract velocity time integral (LVOT-VTI) and cardiac output (CO) in elderly patients undergoing supratentorial neurosurgical procedures using transesophageal echocardiography. We recruited 28 patients aged above 65years undergoing supratentorial craniotomy who received equiosmolar solutions of 5.35ml/kg of 3% HTS (group HS, n= 14) or 5ml/kg of 20% mannitol (group M, n= 14). LVOT-VTI was recorded at baseline, 15, 30, 45, 60, and 90minutes postinfusion and CO was derived. We also recorded heart rate, blood pressure, fluid balance, brain relaxation, vasopressor use, complications, and neurological outcome. We found a significant decrease in LVOT-VTI at 45, and 60minutes in group M as compared to group HS [mean (standard deviation), 16.76 (1.81) vs. 20.78 (1.87), P<0.001, 17.4 (2.38) vs. 19.16 (2), P=0.044, respectively]. We also found a corresponding significant fall in CO [3863.16 (845.87) vs. 4745.59 (1209.33) ml/minute, P=0.034] and systolic blood pressure (P=0.039), at 45minutes in group M. Urine output was higher in group M (P<0.001). All other parameters were comparable. HTS appears to be associated with better systemic hemodynamics (LVOT-VTI, CO) while providing equivalent brain relaxation as mannitol in elderly patients. A future larger study is required to confirm our preliminary findings.

Low left ventricular outflow tract velocity time integral predicts normotensive shock in patients with acute pulmonary embolism

In this study, we found that a low LVOT VTI (<15 cm), a simple bedside point-of-care measurement, predicts normotensive shock in patients with acute intermediate-risk PE.

Septic cardiomyopathy phenotype in the critically ill may depend on antimicrobial resistance

BackgroundSepsis is a life-threatening organ dysfunction, and septic cardiomyopathy (SCM) may complicate the course of the disease. Infection with multidrug-resistant (MDR) pathogens has been linked with worse outcomes. This study aims to evaluate SCM in patients with infections caused by different antimicrobial-resistant phenotypes. MethodThis retrospective study included patients with sepsis/septic shock, hospitalized, and intubated in the intensive care unit of the University Hospital of Larissa between January 2022 and September 2023 with echocardiographic data during the first two days after infection onset. The patients were divided into two groups: non-MDR-SCM group and MDR-SCM group. The cardiac function was compared between the two groups. ResultA total of 62 patients were included in the study. Forty-four patients comprised the MDR-SCM and 18 the non-MDR-SCM group. Twenty-six patients (41.9%) presented with left ventricular (LV) systolic dysfunction, and ≤35% right ventricular fractional area change (RVFAC) was present in 56.4%. LV systolic function was more severely impaired in the non-MDR-SCM group (left ventricular ejection fraction, 35.8% ±4.9% vs. 45.6%±2.4%, P=0.049; LV outflow tract velocity time integral, [10.1±1.4] cm vs. [15.3±0.74] cm, P=0.001; LV-Strain, –9.02%±0.9% vs. –14.02%±0.7%, P=0.001). The MDR-SCM group presented with more severe right ventricular (RV) dilatation (right ventricular end-diastolic area/left ventricular end-diastolic area, 0.81±0.03 vs. 0.7±0.05, P=0.042) and worse RV systolic function (RVFAC, 32.3%±1.9% vs. 39.6%±2.7%, P=0.035; tricuspid annular plane systolic excursion, [15.9±0.9] mm vs. [18.1±0.9] mm, P=0.165; systolic tissue Doppler velocity measured at the lateral tricuspid annulus, [9.9±0.5] cm/s vs. [13.1±0.8] cm/s, P=0.002; RV-strain, –11.1%±0.7% vs. –15.1%±0.9%, P=0.002). ConclusionSCM related to MDR infection presents with RV systolic dysfunction predominance, while non-MDR-SCM is mainly depicted with LV systolic dysfunction impairment.

Diagnostic accuracy of left ventricular outflow tract velocity time integral versus inferior vena cava collapsibility index in predicting post-induction hypotension during general anesthesia: an observational study.

Point of care ultrasound (POCUS) is being explored for dynamic measurements like inferior vena cava collapsibility index (IVC-CI) and left ventricular outflow tract velocity time integral (LVOT-VTI) to guide anesthesiologists in predicting fluid responsiveness in the preoperative period and in treating post-induction hypotension (PIH) with varying accuracy. In this prospective, observational study on included 100 adult patients undergoing elective surgery under general anesthesia, the LVOT-VTI and IVC-CI measurements were performed in the preoperative room 15 minutes prior to surgery, and PIH was measured for 20 minutes in the post-induction period. The incidence of PIH was 24%. The area under the curve, sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of the two techniques at 95% confidence interval was 0.613, 30.4%, 93.3%, 58.3%, 81.4%, 73.6% for IVC-CI and 0.853, 83.3%, 80.3%, 57.1%, 93.8%, 77.4% for LVOT-VTI, respectively. In multivariate analysis, the cutoff value for IVC-CI was >51.5 and for LVOT-VTI it was ≤17.45 for predicting PIH with odd ratio [OR] of 8.491 (P=0.025) for IVCCI and OR of 17.427 (P<0.001) for LVOT. LVOT-VTI assessment was possible in all the patients, while 10% of patients were having poor window for IVC measurements. We recommend the use of POCUS using LVOT-VTI or IVC-CI to predict PIH, to decrease the morbidity of patients undergoing surgery. Out of these, we recommend LVOT-VTI measurements as it has showed a better diagnostic accuracy (77.4%) with no failure rate.

The left ventricular outflow tract and carotid artery velocity time integrals

The left ventricular outflow tract velocity time integral (LVOT VTI) is commonly used in the intensive care unit as a measure of stroke volume (SV) and how the SV changes in response to an intervention; therefore, the LVOT VTI is used to guide intravenous fluid management. Various peripheral Doppler surrogates are proposed to infer the LVOT VTI (e.g., measures from the common carotid artery). A recently-described, novel method of insonation has an excellent ability to detect change in the LVOT VTI. This approach raises important facets of Doppler flow and insonation error, as well as the general principles at play when using a peripheral artery to infer changes from the left ventricle. Relating the VTI of a peripheral artery to the LVOT VTI was recently described mathematically and may help clinicians think about the Doppler relationship between central and peripheral flow.

Association between speckle tracking echocardiography and pressure-volume loop derived parameters at increasing levels of myocardial damage in a porcine model of acute cardiogenic shock

Abstract Background Echocardiography is a diagnostic cornerstone in acute cardiovascular care. However, the relationship between speckle tracking assessed global longitudinal strain (LS) and Doppler-based echocardiography with basic physiological markers of cardiac function derived from pressure-volume loops remains poorly elucidated, especially with increasing levels of myocardial damage. Objectives We aimed to describe the association between LS and Doppler-based echocardiography and direct measurements of central hemodynamic parameters from conductance catheter-based pressure-volume loops in an animal model with increasing left ventricular (LV) dysfunction. Methods Twelve Danish landrace pigs weighing 75-80 kg were used. All instrumentations were performed percutaneously, including placement of a conductance catheter in the LV. Progressive LV dysfunction was induced by stepwise embolization trough the left main coronary artery every three minutes until a 50% reduction in cardiac output or mixed venous saturation, compared to baseline, or a mixed venous saturation &amp;lt;30%. Echocardiography was performed through a subxiphoid midline incision, and was done at baseline and 90 seconds after each injection. Results With progressive LV dysfunction, mean cardiac output decreased from 5.6 l/min (SD: 0.9) to 2.1 l/min (SD: 0.9) and mean mixed venous saturation deteriorated from 61.1%(SD: 7.9) to 35.3% (SD: 6.1). Mean LS and LV outflow tract velocity time integral (LVOT VTI) declined from -13.8% (SD 3.0) to -6.1% (SD: 2.0) and 16.9 cm (SD: 2.6) to 7.8 cm (SD: 1.8), respectively (Figure 1). LS and LVOT VTI showed the strongest correlation to stroke work in unadjusted univariate regression (r2=0.53 and r2=0.49, respectively. p&amp;lt;0.01 for both). LS correlated significantly, but modest, with stroke volume (r2=0.46, p&amp;lt;0.01), end-systolic elastance (r2=0.32, p&amp;lt;0.01), systolic blood pressure (r2=0.37, p&amp;lt;0.01), ventriculo-arterial coupling(r2=0.34, p&amp;lt;0.01), and arterial elastance (r2=0.23, p&amp;lt;0.01) (Figure 2). In a multivariate regression analysis, LS showed significant correlation with stroke work, systolic blood pressure, and end-diastolic wall stress (r2=0.60, p&amp;lt;0.01). Conclusion In an animal model of acute progressive LV dysfunction, echocardiographic and conductance catheter-based measurements changed significantly. LS and LVOT VTI displayed the earliest and the largest alterations with increased myocardial damage and LS showed moderate correlations with contractility, arterial elastance and ventriculo-arterial coupling. This indicates that LS is a marker of overall ventricular performance.Echocardiographic changes from baselineScatter plot of LS and hemodynamics

Abstract 13250: Establishing Partition Values and Clinical Phenotype for Heart Failure Patients With Abnormal Left Atrial Function Index: A Cross-Sectional Analytical Study

Introduction: Left atrial function index (LAFI) has recently been validated for global estimation of left atrial (LA) function. LA dysfunction is critical to developing overt heart failure (HF), and getting the best tool for assessing its function is critical to HF prevention. This study attempts to establish cut-off values for LAFI among HF patients and identify which HF phenotype is associated with abnormal LAFI. Hypothesis: Is there any association between abnormal LAFI and changes in LV function? Methods: This cross-sectional study was conducted at the Delta State University Teaching Hospital, Nigeria. We recruited 80 hypertensive HF patients and 40 healthy normotensive controls. LAFI = (LAEF x LVOT-VTI)/LAESVI. (LAEF = left atrial emptying fraction; LAESVI = left atrial end-systolic volume index; LVOT-VTI = left ventricular outflow tract velocity time integral). Relationships between variables were determined using an independent student’s t-test, and a P-value of &lt;0.05 was significant. Results: In the control arm, the LAFI reference range was estimated to be 24.07-76.24. Abnormal LAFI was defined as LAFI &lt; 24 and 77.5% of the individuals with HF were found to have abnormal LAFI. There was no difference in age (61.83±7.48 vs. 63.22±6.75, p=0.46), BMI (28.27±4.47 vs. 29.52±5.91, p=0.33) and systolic BP (127.34±19.28 vs. 120.94±19.94, p=0.22) of hypertensive HF patients with LAFI &lt;24 and LAFI ≥24. Those with abnormal LAFI had lower EF (45.04±11.06 vs. 63.73±14.73, p&lt;0.0001), FS (25.75±8.26 vs 32.49±8.64, p=0.003) and SV (57.16±13.30 vs. 64.99±16.94, p=0.02). However, E/E’ (15.62±5.61 vs. 9.2±3.22, p&lt;0.0001) and LAVI (37.22±5.80 vs. 16.48±5.65, p&lt;0.0001) were higher among patients with lower LAFI. Contrarily, E/A (1.87±0.97 vs. 1.87±0.83, p=0.98) and TAPSE (17.87±3.67 vs. 19.54±2.47, p=0.06) did not show any difference among the groups. Conclusions: This study shows that abnormal LAFI was associated with impaired LV function and it is crucial to deploy this non-invasive modality of cardiac assessment in hypertensive patients. Early identification of abnormal left atrial mechanics is pertinent to preventing overt HF, especially in parts of the world where access to advanced cardiovascular care is limited.

Determinants of right ventricular systolic dysfunction among patients with left heart failure in a Ghanaian hospital.

The presence of right ventricular dysfunction affects outcomes in patients with left heart failure. We assessed the determinants of right ventricular systolic dysfunction (RVSD) among patients with left heart failure presenting to the Korle Bu Teaching Hospital of Ghana. Consecutive patients with left heart failure who were 18 years and above were prospectively enrolled and assessed for evidence of RVSD by measuring the tricuspid annular plane systolic excursion, the peak velocity of the tricuspid annulus in systole (RV S'), the two-dimensional right ventricular fractional area change (RV FAC) and the right ventricular myocardial performance index (RV MPI). Two hundred and seventy participants were enrolled, of whom 75.2% had at least one abnormal index of right ventricular systolic function. The prevalence of RVSD was significantly higher among those with non-hypertensive heart failure (85.3 vs 66.0%, p < 0.001). The left ventricular outflow tract velocity-time integral (LVOT VTI) was strongly correlated with the RV FAC and an LVOT VTI < 9.8 cm predicted the presence of an RV FAC < 35% with a sensitivity of 81.5% and specificity of 81.9% [area under the curve 0.882; 95% confidence interval (CI): 0.838-0.926, p < 0.001]. Independent predictors of the presence of RVSD included a transmitral E/A > 2 [odds ratio (OR) = 4.684, 95% CI: 1.521-14.428, p = 0.007), left ventricular ejection fraction < 40% (OR = 4.205, 95% CI: 1.643-10.760, p = 0.003), pulmonary artery systolic pressure (PASP) ≥ 35 mmHg (OR = 2.434, 95% CI: 1.012-5.852, p = 0.047) and systemic systolic blood pressure (SBP) < 140 mmHg (OR = 2.631, 95% CI: 1.152-6.011, p = 0.022). RVSD was common in these Ghanaian patients with left heart failure. Left ventricular function, SBP and PASP were independent predictors of the presence of RVSD. Pending further validation, the LVOT VTI may serve as a useful surrogate or screening tool for RVSD in these patients.

Association of Shock Index with Echocardiographic Parameters in Cardiac Intensive Care Unit

BackgroundA high shock index (SI), the ratio of heart rate (HR) to systolic blood pressure (SBP), has been associated with unfavorable outcomes. We sought to determine the hemodynamic underpinnings of an elevated SI using 2-D and doppler Transthoracic Echocardiography (TTE) in unselected cardiac intensive care unit (CICU) patients. MethodsWe included Mayo Clinic CICU admissions from 2007 to 2018 who were in sinus rhythm at the time of TTE. The SI was calculated using HR and SBP at the time of TTE. Patients were grouped according to SI: <0.7, 4012 (64%); 0.7–0.99, 1764 (28%); and ≥ 1.0, 513 (8%). Pearson's correlation coefficient was used to assess associations between continuous variables. ResultsWe included 6289 unique CICU patients, 58% of whom had acute coronary syndrome. The median age was 67.9 years old and 37.8% were females. The mean SI was 0.67 BPM/mmHg. As the SI increased, markers of left ventricular (LV) systolic function and forward flow decreased, including left ventricular ejection fraction (LVEF), fractional shortening, left ventricular outflow tract (LVOT) velocity time integral (VTI), stroke volume, LV stroke work index, and cardiac power output. Biventricular filling pressures increased, and markers of right ventricular function worsened with rising SI. Most TTE measurements reflecting LV function and forward flow were inversely correlated with SI, including LV stroke work index (r = −0.59) and LVOT VTI (r = −0.41), as were both systemic vascular resistance index (r = −0.43) and LVEF (r = −0.23). ConclusionCICU patients with elevated SI have worse biventricular function and systemic hemodynamics, particularly decreased stroke volume and related calculated TTE parameters. The SI is an easily available marker that can be used to identify CICU patients with unfavorable hemodynamics who may require further assessment.

Reliability of point-of-care ultrasound to evaluate fluid tolerance performed by critical care residents

BackgroundPatients with hypotension usually receive intravenous fluids, but only 50% will respond to fluid administration. We aimed to assess the intra and interobserver agreement to evaluate fluid tolerance through diverse ultrasonographic methods.MethodsWe prospectively included critically ill patients on mechanical ventilation. One trained intensivist and two intensive care residents obtained the left ventricular outflow tract velocity–time integral (VTI) variability, inferior vena cava (IVC) distensibility index, internal jugular vein (IJV) distensibility index, and each component of the venous excess ultrasound (VExUS) system. We obtained the intraclass correlation coefficient (ICC) and Gwet’s first-order agreement coefficient (AC1), as appropriate.ResultsWe included 32 patients. In-training observers were unable to assess the VTI-variability in two patients. The interobserver agreement was moderate to evaluate the IJV-distensibility index (AC1 0.54, CI 95% 0.29–0.80), fair to evaluate VTI-variability (AC1 0.39, CI 95% 0.12–0.66), and absent to evaluate the IVC-distensibility index (AC1 0.19, CI 95% − 0.07 to 0.44). To classify patients according to their VExUS grade, the intraobserver agreement was good, and the interobserver agreement was moderate (AC1 0.52, CI 95% 0.34–0.69).ConclusionsPoint-of-care ultrasound is frequently used to support decision-making in fluid management. However, we observed that the VTI variability and IVC-distensibility index might require further training of the ultrasound operators to be clinically useful. Our findings suggest that the IJV-distensibility index and the VExUS system have acceptable reproducibility among in-training observers.

Effect of assessing velocity time integral at different locations across ventricular outflow tracts when calculating cardiac output in neonates

This study aims to evaluate the effect of assessing velocity time integral at different locations across ventricular outflow tracts for calculating cardiac output (CO) in neonates. Velocity time integral (VTI) and CO were measured at 3 different locations across right and left ventricular outflow tracts using transthoracic echocardiography in healthy term neonates without any major congenital heart disease. ANOVA with Bonferroni correction was used to determine the differences between the VTI and CO sampled at these three locations. Forty-one neonates met inclusion criteria with mean gestational age of 38.6 ± 1 weeks and mean birth weight of 3155 ± 463 g. The median hours after birth when echocardiography was obtained was 23 h (range 11–68 h after birth). Left CO were 121 ± 30 mL/kg/min, 155 ± 38 mL/kg/min, and 176 ± 36 mL/kg/min measured below the valve, hinges of the valve, and tip of the valve, respectively. Right CO were 197 ± 73 mL/kg/min, 270 ± 83 mL/kg/min, and 329 ± 104 mL/kg/min measured below the valve, hinges of the valve, and tip of the valve, respectively. A statistically significant difference (P < 0.001) was found in the VTI and CO measured at the 3 different locations across both left and right ventricular outflow tracts. Conclusions: There is a significant difference in measurements of VTI and CO depending on the location of Doppler gate sampling across the ventricular outflow tracts. Consistency and precision in Doppler gate location are essential for measuring VTI and calculating CO while assessing changes in hemodynamic status in critically ill infants.What is Known:• Targeted Neonatal Echocardiography is increasingly applied to measure cardiac output in critically ill neonates and serial assessments are performed to assess the trend in changes in cardiac output.• Noninvasive measurement using velocity time integral to calculate cardiac output is commonly performed. However, location of Doppler sample gate to measure ventricular outflow tract velocity time integral is not consistent.What is New:• Statistically significant changes in measured velocity time integral and cardiac output are noted based on the location of Doppler gate sampling.• To monitor the cardiac output for trending, it is important to be consistent with regards to the location of the Doppler sample gate to assess changes in cardiac output in critically ill newborns.

Fluid Responsiveness in Critically Ill Patients Using Carotid Peak Systolic Velocity Variability: A New Frontier.

Background and objectives A fluid responder is a patient who can increase his stroke volume/ cardiac output by more than 10%-15% after a fluid bolus. Left ventricular outflow tract (LVOT) velocity time integral (VTI) variability is widely used as an adynamic parameter of fluid responsiveness, but a transthoracic echo view of LVOT VTI is often time-consuming and, at times, difficult to achieve. So, in the quest for another parameter that might equally be a good surrogate marker of stroke volume variation, carotid peak systolic velocity (CPSV) variation has been studied. The objective was to assess CPSV variation in patients who are already fluid responders. Methods The sample size was calculated considering a minimum correlation coefficient of 0.5. Adult patients in whom the physician wanted to give a fluid bolus and whose average LVOT VTI was more than 15% over 3 respiratory cycles were included in the study. Demographic variables, along with hemodynamic parameters such as heart rate, blood pressure, the need for vasopressors, mode of breathing (spontaneous or mechanical ventilation), andCPSV variation,were noted and averaged over three respiratory cycles. Fluid bolus (Plasmalyte) 6 ml/kg bolus over 10-15 minutes. Post-fluid hemodynamic variables, along with averaged LVOT VTI over three respiratory cycles and averaged CPSV variation over three respiratory cycles, are noted. Results Thirty adult patients were evaluated in the study. In spontaneously breathing patients (n=12), the average CPSV variation expressed as mean + standard deviation before and after fluid administration of 6ml/kg of ideal body weight was 14.1 ± 3.4 and 5.4 ± 2.6, respectively (p < 0.05). In mechanically ventilated patients (n=18), the average CPSV variation expressed as mean + standard deviation before and after fluid administration of 6ml/kg of ideal body weight fluid was 15 ± 5.3 and 6.5 ± 3.1, respectively (p <0.005). Overall, there was a statistically significant positive correlation between LVOT VTI variation and CPSV variation before fluid therapy (correlation coefficient 0.56 and p-value 0.001) and a statistically significant moderate positive correlation post-fluid therapy (correlation coefficient 0.37 and p-value 0.043). Conclusion We found a significant decrease in CPSV variation post-fluid administration in patients who are fluid responders, which mimics a decrease in stroke volume variation after fluid administration in patients who are fluid responsive.