Assessment of propagation velocity by contrast echocardiography for standardization of color Doppler propagation velocity measurements

The assessment of left ventricular diastolic function: guidance and recommendations from the British Society of Echocardiography

Impairment of left ventricular (LV) diastolic function is common amongst those with left heart disease and is associated with significant morbidity. Given that, in simple terms, the ventricle can only eject the volume with which it fills and that approximately one half of hospitalisations for heart failure (HF) are in those with normal/'preserved' left ventricular ejection fraction (HFpEF) (Bianco et al. in JACC Cardiovasc Imaging. 13:258-271, 2020. 10.1016/j.jcmg.2018.12.035), where abnormalities of ventricular filling are the cause of symptoms, it is clear that the assessment of left ventricular diastolic function (LVDF) is crucial for understanding global cardiac function and for identifying the wider effects of disease processes. Invasive methods of measuring LV relaxation and filling pressures are considered the gold-standard for investigating diastolic function. However, the high temporal resolution of trans-thoracic echocardiography (TTE) with widely validated and reproducible measures available at the patient's bedside and without the need for invasive procedures involving ionising radiation have established echocardiography as the primary imaging modality. The comprehensive assessment of LVDF is therefore a fundamental element of the standard TTE (Robinson et al. in Echo Res Pract7:G59-G93, 2020. 10.1530/ERP-20-0026). However, the echocardiographic assessment of diastolic function is complex. In the broadest and most basic terms, ventricular diastole comprises an early filling phase when blood is drawn, by suction, into the ventricle as it rapidly recoils and lengthens following the preceding systolic contraction and shortening. This is followed in late diastole by distension of the compliant LV when atrial contraction actively contributes to ventricular filling. When LVDF is normal, ventricular filling is achieved at low pressure both at rest and during exertion. However, this basic description merely summarises the complex physiology that enables the diastolic process and defines it according to the mechanical method by which the ventricles fill, overlooking the myocardial function, properties of chamber compliance and pressure differentials that determine the capacity for LV filling. Unlike ventricular systolic function where single parameters are utilised to define myocardial performance (LV ejection fraction (LVEF) and Global Longitudinal Strain (GLS)), the assessment of diastolic function relies on the interpretation of multiple myocardial and blood-flow velocity parameters, along with left atrial (LA) size and function, in order to diagnose the presence and degree of impairment. The echocardiographic assessment of diastolic function is therefore multifaceted and complex, requiring an algorithmic approach that incorporates parameters of myocardial relaxation/recoil, chamber compliance and function under variable loading conditions and the intra-cavity pressures under which these processes occur. This guideline outlines a structured approach to the assessment of diastolic function and includes recommendations for the assessment of LV relaxation and filling pressures. Non-routine echocardiographic measures are described alongside guidance for application in specific circumstances. Provocative methods for revealing increased filling pressure on exertion are described and novel and emerging modalities considered. For rapid access to the core recommendations of the diastolic guideline, a quick-reference guide (additional file 1) accompanies the main guideline document. This describes in very brief detail the diastolic investigation in each patient group and includes all algorithms and core reference tables.

Left Ventricular Energy Loss Assessed by Vector Flow Mapping in Patients with Prediabetes and Type 2 Diabetes Mellitus

The aim of this study was to assess left ventricular (LV) energy loss (EL) using vector flow mapping in patients with prediabetes (pre-DM) and type 2 diabetes mellitus (DM). Thirty pre-DM patients, 51 DM patients, and 38 controls were studied by transthoracic echocardiography. EL-total, EL-base, EL-mid and EL-apex climaxed at different phases. Compared with controls, pre-DM and DM patients showed increased EL-total during slow ejection, isovolumic relaxation, rapid filling and slow filling (p < 0.05). Similarly, EL-base, EL-mid and EL-apex increased during certain phases. Stepwise multiple regression analysis revealed that the early transmitral valve blood flow velocity E, the late transmitral valve blood flow velocity A, the ratio of E/A, LV peak torsion, diastolic untwisting velocity, vortex circulation and area were independently associated with EL during different phases (all p < 0.05). Our study suggests that LV EL is increased during diastole and certain phases of systole in DM patients compared with controls. The changes in LV vortex and deformation mechanics were correlated with EL.

Subendocardial Systolic Dysfunction in Asymptomatic Normotensive Diabetic Patients

BACKGROUND

It remains uncertain whether diabetes itself causes specific echocardiographic features of myocardial morphology and function in the absence of hypertension or ischemic heart disease. The purpose of the present study was to determine the characteristics of pure diabetic cardiomyopathy-related echocardiographic morphology and function using layer-by-layer evaluation with myocardial strain echocardiography.

METHODS AND RESULTS

We enrolled 104 patients with poorly controlled type 2 diabetes mellitus (mean HbA1c level, 10%) with (n=74) or without (n=40) hypertension and 24 age- and sex-matched healthy volunteers. Patients with coronary artery stenosis or structural heart disease were excluded. Myocardial layer-specific strain was analyzed by speckle tracking echocardiography. Compared with the healthy control group, the normotensive diabetes group showed no significant difference in ejection fraction, left ventricular mass index, diastolic properties, left atrial volume index, or B-type natriuretic protein (BNP) level, but global longitudinal strain and subendocardial radial strain were significantly deteriorated. The deterioration of longitudinal strain correlated with body mass index (R=0.49, P<0.01) and blood pressure (R=0.36, P<0.01) in the normotensive diabetes group.

CONCLUSIONS

Deterioration of left ventricular longitudinal shortening accompanied by decreased subendocardial wall thickening are the characteristic functional abnormalities of diabetic cardiomyopathy in patients without hypertrophy, diastolic dysfunction, or elevated BNP. Obesity and blood pressure may also play important roles in this strain abnormality in asymptomatic patients with type 2 diabetes.

Abnormal early diastolic intraventricular flow 'kinetic energy index' assessed by vector flow mapping in patients with elevated filling pressure

AIMS

Recently developed vector flow mapping (VFM) enables evaluation of local flow dynamics without angle dependency. This study used VFM to evaluate quantitatively the index of intraventricular haemodynamic kinetic energy in patients with left ventricular (LV) diastolic dysfunction and to compare those with normal subjects.

METHODS AND RESULTS

We studied 25 patients with estimated high left atrial (LA) pressure (pseudonormal: PN group) and 36 normal subjects (control group). Left ventricle was divided into basal, mid, and apical segments. Intraventricular haemodynamic energy was evaluated in the dimension of speed, and it was defined as the kinetic energy index. We calculated this index and created time-energy index curves. The time interval from electrocardiogram (ECG) R wave to peak index was measured, and time differences of the peak index between basal and other segments were defined as ΔT-mid and ΔT-apex. In both groups, early diastolic peak kinetic energy index in mid and apical segments was significantly lower than that in the basal segment. Time to peak index did not differ in apex, mid, and basal segments in the control group but was significantly longer in the apex than that in the basal segment in the PN group. ΔT-mid and ΔT-apex were significantly larger in the PN group than the control group. Multiple regression analysis showed sphericity index, E/E' to be significant independent variables determining ΔT apex.

CONCLUSION

Retarded apical kinetic energy fluid dynamics were detected using VFM and were closely associated with LV spherical remodelling in patients with high LA pressure.

Peak C-reactive protein concentration correlates with left ventricular thrombus formation diagnosed by contrast echocardiographic left ventricular opacification in patients with a first anterior acute myocardial infarction

BACKGROUND

Wall motion abnormality in the apical legion of the left ventricle (LV) with stagnant flow alone is not sufficient to identify patients at high risk for LV thrombus formation among those with first anterior acute myocardial infarction (AMI). The aim of this study was to identify the determinants of LV thrombus formation using contrast echocardiography.

METHODS AND RESULTS

In 75 patients with first anterior AMI, standard and contrast echocardiography was performed to detect LV thrombus. Although LV thrombus was found in 10 patients (13%) using standard echocardiography, it was found in 15 patients (20%) using contrast echocardiography. Apical stagnant flow was observed in 14 patients (93%) with LV thrombus. In addition, patients with LV thrombus had a higher peak C-reactive protein (CRP) concentration (18.2+/-4.3 vs 7.9+/-5.5 mg/dl, p<0.0001). In multivariate analysis, only peak CRP concentration was identified as an independent predictor of LV thrombus (p=0.02, odds ratio: 1.400, confidence interval: 1.040-1.884). The receiver-operating characteristics (ROC) analysis revealed the best cutoff value of a peak CRP concentration >10.7 mg/dl to identify patients with LV thrombus (sensivity 0.93, specificity 0.75, area under ROC curve 0.91).

CONCLUSIONS

The peak CRP concentration is a useful marker of patients with first anterior AMI who are at high risk for LV thrombus.

The Wake of a Large Vortex Is Associated with Intraventricular Filling Delay in Impaired Left Ventricles with a Pseudonormalized Transmitral Flow Pattern

Although an intraventricular filling delay has been observed in patients with a psuedonormalized transmitral flow pattern, little is known about the underlying hydrodynamic nature of this phenomenon.

METHODS

To examine those hydrodynamics, we studied every echocardiographic frame showing ventricular inflow (80 Hz) in the apical long-axis view and M-mode image using contrast echocardiography in 29 patients with a psuedonormalized pattern and in 26 normal controls. The velocity of the filling flow front (Vp), the ratio of Vp to E, and the mean radius of the vortices associated with the filling flow were measured.

RESULTS

In both groups, vortices were observed at the ridge of the mitral valve during acceleration of the E-wave. The mean radius of the vortices was greater in the pseudonormalized filling group than that in the control group (8 +/- 2 vs 3 +/- 1 mm, P < 0.0001). Vp was smaller in the pseudonormalized group than in the control group (36 +/- 6 vs 47 +/- 6 cm/sec, P = 0.0008). Vp/E was < 1 and smaller in the pseudonormalized group than that in the control group (0.46 +/- 0.13 vs 0.59 +/- 0.07, P = 0.014) and negatively correlated with the mean radius of the vortices (r = 0.54, P < 0.0001).

CONCLUSIONS

Contrast echocardiography identified uniform flow characteristics with blood in the filling flow front moving in well-developed vortices and resulting in a left ventricular filling delay in the impaired left ventricle in spite of an increased early transmitral flow velocity.