Diastolic Flow Pattern Research Articles

Diastolic dysfunction: assessment and implications on the single ventricle circulation.

Patients with a functionally single ventricle (SV) are palliated with a series of procedures leading to a Fontan circulation. Over the life span, a substantial proportion of SV patients develop heart failure that can arise from circulatory or ventricular failure. Diastolic dysfunction (DD) is an important determinant of adverse outcomes in SV patients. However, assessment and categorization of DD in the SV remains elusive. We review recent literature and developments in assessment of DD in the SV and its relation to clinical outcomes. DD is prevalent in the SV and associated with worse outcomes. Occult DD can be exposed with provocative testing by exercise or preload challenge during catheterization. Likewise, sensitivity to detect DD may be increased via assessment of atrial function and strain imaging. Recent studies revisiting previous concepts such as incoordinate diastolic wall motion show that these are associated with SV end-diastolic pressures and post-Fontan recovery, yielding accessible DD assessment. Emerging technologies such as ultrafast ultrasound (UFUS) can provide noninvasive assessment of myocardial stiffness, inefficient diastolic flow patterns and intraventricular pressure gradients, thereby yielding new tools and insights into diastolic myocardial and hemodynamic properties. Characterizing DD in the SV continues to have substantial limitations, necessitating synthesis of multiple parameters into an overall assessment, accounting for their change over time, and in the context of the patient's clinical status. New and emerging techniques may help advance DD assessment and the ability to track response to treatment of new targets.

Acute Coronary Syndrome Treated with Percutaneous Coronary Intervention in Hutchinson–Gilford Progeria

Hutchinson-Gilford progeria syndrome is an extremely rare genetic disease caused by a de novo mutation in the LMNA gene, leading to an accumulation of a form of Lamin A, called Progerin, which results in a typical phenotype and a marked decrease in life expectancy, due to early atherosclerosis and cardiovascular disease. We report the case of a fourteen-year-old Chinese boy with Hutchinson-Gilford progeria syndrome admitted to the emergency room because of precordial pain. Physical examination showed tachycardia 130 beats/min and arterial hypertension: 170/120 mmHg, normal respiratory rate, no neurological impairment; ECG evidenced sinus tachycardia, left ventricular hypertrophy, horizontal ST-segment depression in I, aVL, II, III, aVF leads, and V4-V6 and ST-segment elevation in aVR and V1 leads. Echocardiography highlighted preserved global left ventricular function with concentric hypertrophy, altered diastolic flow pattern, mitral valve insufficiency, and minimal aortic regurgitation. Blood tests evidenced an increase in high-sensitivity troponin T level (335 pg/mL). NSTEMI diagnosis was performed, and the patient was admitted to the intensive care unit. A coronary CT angiography showed a severe obstruction of the common trunk of the left coronary artery, for which an urgent percutaneous coronary intervention (PCI) was proposed. A selective coronary angiography imaged complete chronic occlusion of the left main coronary artery as well as severe stenosis at the origin of a very enlarged right coronary artery that vascularized the left coronary artery through collaterals. Afterwards, the right coronary artery was probed using an Amplatz right (AR1) guiding catheter, through which a large 3.5 mm drug-eluting coronary stent (Xience Sierra, Abbott, Abbott Park, IL, USA) was implanted. At the end of the procedure, no residual stenosis was imaged and improved vascularization of the left coronary artery distribution segments was observed. Dual antiplatelet therapy (DAPT) consisting of aspirin (75 mg daily) and clopidogrel (37.5 mg daily) and anti-hypertensive therapy were started. At the one-year follow-up, the patient had not reported any occurrence of anginal chest pain.

Role of Vector Flow Mapping in Evaluating Left Ventricular Diastolic Flow Dynamics in Patients Who Underwent Mitral Valve Repair for Degenerative Mitral Regurgitation.

Mitral valve (MV) morphology after MV repair affects postoperative left ventricular (LV) blood flow pattern and long-term cardiac function. Pilot data suggest that LV diastolic vortex flow pattern changes after operation, but specific quantifiers remain unknown. We aimed to explore the role of vector flow mapping (VFM) in LV diastolic vortex flow pattern in patients who underwent MV repair. A total of 70 patients with degenerative mitral regurgitation were consecutively enrolled and 30 age- and gender-matched controls were recruited. 50 Patients who underwent MV repair were eventually included in our study. LV average energy loss (EL-AVE) during diastole was measured in the MV repair group by VFM one week before and one month after the operation, and compared with that of controls using one-way analysis of variance. The effect of surgical techniques and the extension of leaflet degeneration on postoperative EL-AVE were analyzed using muti-way analysis of variance, and patients were categorized into a resection subgroup (n = 29) and a non-resection subgroup (n = 21). The EL-AVE one month after operation in the MV repair group was decreased (p 0.001) compared to that one week before the operation, and was increased (p 0.001) compared to that in controls. Mitral leaflet resection had a statistically significant effect on postoperative EL-AVE. The EL-AVE of the resection subgroup was higher than that of non-resection subgroup (p 0.001). VFM can be used to evaluate the diastolic blood flow pattern of LV after MV repair, and to observe the changes of LV blood flow pattern caused by different surgical techniques. VFM may be a potential new hemodynamic evaluation method after MV repair.

Preservation of left ventricle peak and mean pulse flow blood velocity despite progressive deterioration of cardiac function in a chronic heart failure murine model.

The goal of this study was to assess the alterations in left ventricle (LV) blood flow velocity patterns in relation to progressive impairment of cardiac function in the course of heart failure (HF) in a unique murine model of chronic HF in Tgαq*44 mice. Doppler- and MRI-based assessments of blood velocity and cardiac performance, respectively, were performed in Tgαq*44 mice at the age of 1, 2, 4, 6, 8 and 12 months as compared with age-matched FVB control mice. One-month-old Tgαq*44 mice displayed elongated early diastolic phase with fully preserved cardiac function that, however, progressively deteriorated in older Tgαq*44 mice. As early as in 2-month-old Tgαq*44 mice, the filling rate (FR), max. radial strain and end-systolic volume increased; in 4-month-old Tgαq*44 mice, the ejection fraction, max. circ. strain and ventriculo-arterial coupling decreased, and the ejection time was prolonged; in 6 - 8-month-old Tgαq*44 mice, the stroke volume, max. (both) strains decreased, end-systolic volume, FR and end-diastolic volume increased, and finally, in 12-month-old Tgαq*44 mice, the ejection fraction, cardiac output and stroke volume were all severely impaired. In the early phase of HF development, no differences were observed in Tgαq*44 mice versus FVB mice regarding systolic LV flow pattern, but indices of mitral diastolic flow were considerably increased in 1-month-old Tgαq*44 mice versus FVB mice. In the late phase of HF, despite progressive deterioration of cardiac function, LV pulse flow blood velocity was not altered in Tgαq*44 mice up to the age of 8 months. Systolic peak velocity and mean acceleration time deteriorated only in 12-month-old Tgαq*44 mice, with peak acceleration and mean velocity values still preserved. We demonstrated that the cardiac mitral diastolic flow pattern displayed adaptive changes in the very early phase of HF development in Tgαq*44 mice and that these changes preceded early alterations in LV haemodynamics. Then, despite the progressive deterioration of cardiac haemodynamics, peak and mean in- and out-flow velocities remained unchanged for a relatively long time and deteriorated only at the end-stage HF. Altogether, we revealed that in addition to cardiac performance, adaptive vascular performance represents an important factor determining LV mitral inflow and ejection flow phenotype during the progression of chronic HF in Tgαq*44 mice.

Intraoperative Assessment of Hepatic Vein Tracings in Constrictive Pericarditis During Surgical Pericardiectomy

CONSTRICTIVE PERICARDITIS is characterized by progressive inflammation and fibrosis of the pericardium. It manifests with symptoms of heart failure. The only effective treatment is surgical pericardiectomy. The assessment and diagnosis of constrictive pericarditis with echocardiography is well described with spontaneous ventilation. However, there are limited data on constrictive pericarditis assessment with transesophageal echocardiography with positive pressure ventilation. Also, intraoperative hepatic venous Doppler flow mostly is used intraoperatively to assess the severity of tricuspid regurgitation by focusing on the flow reversal during systole. In this e-challenge, the authors focus on the hepatic vein Doppler tracing as a means to show improvement in diastolic function during positive pressure ventilation in a patient undergoing pericardiectomy. This case demonstrates a severely blunted diastolic flow pattern in the hepatic vein that is reversed after successful pericardiectomy. Also, it shows blunted flow during systole compared to diastole post-pericardiectomy, indicating high right atrial pressure.

Hemodynamic effects of myocardial bridging in patients with hypertrophic cardiomyopathy.

Myocardial bridging (MB) is linked to angina and myocardial ischemia and may lead to sudden cardiac death in patients with hypertrophic cardiomyopathy (HCM). However, it remains unclear how MB affect the coronary blood flow in HCM patients. The aim of this study was to assess the effects of MB on coronary hemodynamics in HCM patients. Fifteen patients with MB (7 HCM and 8 non-HCM controls) in their left anterior descending (LAD) coronary artery were chosen. Transient computational fluid dynamics (CFD) simulations were conducted in anatomically realistic models of diseased (with MB) and virtually healthy (without MB) LAD from these patients, reconstructed from biplane angiograms. Our CFD simulation results demonstrated that dynamic compression of MB led to diastolic flow disturbances and could significantly reduce the coronary flow in HCM patients as compared with non-HCM group (P < 0.01). The pressure drop coefficient was remarkably higher (P < 0.05) in HCM patients. The flow rate change is strongly correlated with both upstream Reynolds number and MB compression ratio, while the MB length has less impact on coronary flow. The hemodynamic results and clinical outcomes revealed that HCM patients with an MB compression ratio higher than 65% required a surgical intervention. In conclusion, the transient MB compression can significantly alter the diastolic flow pattern and wall shear stress distribution in HCM patients. HCM patients with severe MB may need a surgical intervention.NEW & NOTEWORTHY In this study, the hemodynamic significance of myocardial bridging (MB) in patients with hypertrophic cardiomyopathy (HCM) was investigated to provide valuable information for surgical decision-making. Our results illustrated that the transient MB compression led to complex flow patterns, which can significantly alter the diastolic flow and wall shear stress distribution. The hemodynamic results and clinical outcomes demonstrated that patients with HCM and an MB compression ratio higher than 65% required a surgical intervention.

Effect of turbulent models on left ventricle diastolic flow patterns simulation

Vortex structures, as one of the most important features of cardiac flow, have a crucial impact on the left ventricle function and pathological conditions. These swirling flows are closely related to the presence of turbulence in left ventricle which is investigated in the current study. Using an extended model of the left heart, including a fluid-structure interaction (FSI) model of the mitral valve with a realistic geometry, the effect of using two numerical turbulent models, k-ε and Spalart-Allmaras (SA), on diastolic flow patterns is studied and compared with results from laminar flow model. As a result of the higher dissipation rate in turbulent models (k-ε and SA), vortices are larger and stronger in the laminar flow model. Comparing E/A ratio in the three models (Laminar, k-ε, and SA) with experimental data from healthy subjects, it is concluded that the results from k-ε model are more accurate.

The role of echocardiography in the assessment of an iatrogenic coronary fistula

Abstract : We reported the case of a 61-year-old woman with a suspected postinfarction ventricular septal defect. The predominantly diastolic flow pattern at our echocardiographic assessment was inconsistent with this diagnosis. A computed tomography revealed a left anterior descending artery to right ventricle fistula. This case highlights the importance of echocardiographic assessment in the differential diagnosis between ventricular septal defect and coronary artery fistula.

Relationship between the abnormal diastolic vortex structure and impaired left ventricle filling in patients with hyperthyroidism.

Intraventricular hydrodynamics plays an important role in evaluating cardiac function. Relationship between diastolic vortex and left ventricular (LV) filling is still rarely elucidated. The aim of this study was to evaluate the evolution of vortex during diastole in hyperthyroidism (HT) and explore the alteration of hydromechanics characteristics with sensitive indexes.Forty-three patients diagnosed with HT were classified into 2 groups according to whether myocardial damage existed: simple hyperthyroid group (HT1, n = 21) and thyrotoxic cardiomyopathy (HT2, n = 22). Twenty-seven age- and gender-matched healthy volunteers were enrolled as the control group. Offline vector flow mapping (VFM model) was used to analyze the LV diastolic blood flow patterns and fluid dynamics. Hemodynamic parameters, vortex area (A), circulation (C), and intraventricular pressure gradient (ΔP), in different diastolic phases (early, mid, and late) were calculated and analyzed.HT2, with a lower E/A ratio and left ventricular ejection fraction (LVEF), had a larger left atrium diameter (LAD) compared with those of the control group and HT1 (P < .05). Compared with the control group, the vortex size and strength, intraventricular pressure gradient during early and mid-diastole were higher in HT1 and lower in HT2 (P < .05). And in late diastole, the vortex size and strength, intraventricular pressure gradient of HT2 became higher than those of the control group (P < .05). Good correlation could be found between CE and E/A (P < .05), CM and ΔPM (P < .01), CL and FT3 (P < .05).VFM is proven practical for detecting the relationship between the changes of left ventricular diastolic vortex and the abnormal left ventricular filling.

The role of Ivabradine in Diastolic Heart Failure with preserved Ejection Fraction. A Doppler-Echocardiographic study.

Background:Ivabradine (IVA) is effective in patients with coronary artery disease (CAD) or systolic heart failure in sinus rhythm. Its action consists in reducing heart rate (HR) and improving the time of left ventricular (LV) diastolic filling. The aim of this study was to evaluate the effects of IVA added to conventional therapy on patients with diastolic heart failure (DHF) and preserved ejection fraction (HFpEF).Methods:We evaluated 25 patients with DHF in the New York Heart Association (NYHA) Class II-III and sinus rhythm. In these, IVA per os (5 mg/twice a day) was added to the conventional medical therapy and given for 12 weeks. Immediately before the beginning of IVA therapy and 3 months later, patients underwent echocardiographic evaluation by two-dimensional (2D) ultrasound and tissue Doppler imaging (TDI). The patterns of diastolic mitral inflow and pulmonary venous flow were recorded using 2D echocardiography, while the diastolic phase of mitral flow was recorded by TDI, from the lateral mitral annulus.Results:Three months after the addition of IVA to conventional treatment, HR significantly decreased in comparison to the baseline values. On the contrary, the echocardiographic indexes of LV diastolic dysfunction improved.Conclusions:These results testify that the addition of IVA to conventional therapy in patients with HFpEF can improve LV diastolic function evaluated by 2D and tissue Doppler-echocardiographic patterns. These Doppler-echocardiographic results match with the clinical improvement of patients evaluated.

Relationship between the Abnormal Diastolic Vortex Structure and Impaired Left Ventricle Filling in Patients with Hyperthyroidism

Intraventricular hydrodynamics plays an important role in evaluating cardiac function. Relationship between diastolic vortex structures and left ventricular (LV) filling is still rarely reported. This study aimed to evaluate the evolution of intraventricular fluid dynamics during diastole in hyperthyroidism (HT), and to explore the alteration of hydromechanics characteristics with sensitive indices. Forty-three patients diagnosed with HT were divided into two groups according to whether myocardial damage existed: simple hyperthyroid group (HT1, n = 21) and thyrotoxic cardiomyopathy (HT2, n = 22). Twenty-seven age- and gender-matched healthy volunteers were enrolled as the control group. Offline vector flow mapping (VFM model) was used to analysis the LV diastolic blood flow patterns and fluid dynamics. Hemodynamic parameters like area (A), circulation (C) and intraventricular pressure gradient (△P) in different diastolic phase (early, mid, and late) were calculated and analyzed. HT2, with a lower E/A ratio and left ventricular ejection fraction (LVEF), had larger left ventricular end-diastolic diameter (LVEDD) and left atrium diameter (LAD) compared with the control group and HT1(P <0.05). Vortex displayed a typical biphasic temporal course during diastole in these three groups. In early diastole, vortices of the controls were smaller and weaker than those of HT1, larger and stronger than those of HT2 (P < 0.05 for both). Vortices of these three groups increased in mid-diastole at the same pace and differences remained (P < 0.05 for both). Then vortices in HT2 developed so fast that exceeded the control group, but still below HT1 during the end of diastole. The intraventricular pressure gradient during early and mid-diastole (△PE, △PM) were higher in HT1 and lower in HT2 compared with those of the control group (P <0.05). However, the intraventricular pressure gradient (△PL) of HT2 increased and was higher than that of the control group in late diastole (P < 0.05). Good correlation could be found between CE and E/A (P < 0.05), CM and △PM (P < 0.01), CL and FT3 (P < 0.05). VFM can reflect the abnormal left ventricular filling by showing the changes of left ventricular diastolic vortex.

Cross-Sectional Associations of Flow Reversal, Vascular Function, and Arterial Stiffness in the Framingham Heart Study.

Experimental studies link oscillatory flow accompanied by flow reversal to impaired endothelial cell function. The relation of flow reversal with vascular function and arterial stiffness remains incompletely defined. We measured brachial diastolic flow patterns along with vasodilator function in addition to tonometry-based central and peripheral arterial stiffness in 5708 participants (age 47±13 years, 53% women) in the Framingham Heart Study Offspring and Third Generation cohorts. Brachial artery diastolic flow reversal was present in 35% of the participants. In multivariable regression models, the presence of flow reversal was associated with lower flow-mediated dilation (3.9±0.2 versus 5.0±0.2%; P<0.0001) and reactive hyperemic flow velocity (50±0.99 versus 57±0.93 cm/s; P<0.0001). The presence of flow reversal (compared with absence) was associated with higher central aortic stiffness (carotid-femoral pulse wave velocity 9.3±0.1 versus 8.9±0.1 m/s), lower muscular artery stiffness (carotid-radial pulse wave velocity 9.6±0.1 versus 9.8±0.1 m/s), and higher forearm vascular resistance (5.32±0.03 versus 4.66±0.02 log dyne/s/cm5; P<0.0001). The relations of diastolic flow velocity with flow-mediated dilation, aortic stiffness, and forearm vascular resistance were nonlinear, with a steeper decline in vascular function associated with increasing magnitude of flow reversal. In our large, community-based sample, brachial artery flow reversal was common and associated with impaired vasodilator function and higher aortic stiffness. Our findings are consistent with the concept that flow reversal may contribute to vascular dysfunction.

Altered Diastolic Flow Patterns and Kinetic Energy in Subtle Left Ventricular Remodeling and Dysfunction Detected by 4D Flow MRI.

Aims4D flow magnetic resonance imaging (MRI) allows quantitative assessment of left ventricular (LV) function according to characteristics of the dynamic flow in the chamber. Marked abnormalities in flow components’ volume and kinetic energy (KE) have previously been demonstrated in moderately dilated and depressed LV’s compared to healthy subjects. We hypothesized that these 4D flow-based measures would detect even subtle LV dysfunction and remodeling.Methods and ResultsWe acquired 4D flow and morphological MRI data from 26 patients with chronic ischemic heart disease with New York Heart Association (NYHA) class I and II and with no to mild LV systolic dysfunction and remodeling, and from 10 healthy controls. A previously validated method was used to separate the LV end-diastolic volume (LVEDV) into functional components: direct flow, which passes directly to ejection, and non-ejecting flow, which remains in the LV for at least 1 cycle. The direct flow and non-ejecting flow proportions of end-diastolic volume and KE were assessed. The proportions of direct flow volume and KE fell with increasing LVEDV-index (LVEDVI) and LVESV-index (LVESVI) (direct flow volume r = -0.64 and r = -0.74, both P<0.001; direct flow KE r = -0.48, P = 0.013, and r = -0.56, P = 0.003). The proportions of non-ejecting flow volume and KE rose with increasing LVEDVI and LVESVI (non-ejecting flow volume: r = 0.67 and r = 0.76, both P<0.001; non-ejecting flow KE: r = 0.53, P = 0.005 and r = 0.52, P = 0.006). The proportion of direct flow volume correlated moderately to LVEF (r = 0.68, P < 0.001) and was higher in a sub-group of patients with LVEDVI >74 ml/m2 compared to patients with LVEDVI <74 ml/m2 and controls (both P<0.05).ConclusionDirect flow volume and KE proportions diminish with increased LV volumes, while non-ejecting flow proportions increase. A decrease in direct flow volume and KE at end-diastole proposes that alterations in these novel 4D flow-specific markers may detect LV dysfunction even in subtle or subclinical LV remodeling.

Cardiac Ultrasonography in the critical care setting: a practical approach to asses cardiac function and preload for the "non-cardiologist".

Cardiac ultrasonography has become an indispensible tool in the management of hemodynamically unstable critically ill patients. Some consider it as the modern stethoscope. Echocardiography is non-invasive and safe while the modern portable devices allow to be used at the bedside in order to provide fast, specific and vital information regarding the hemodynamic status, as well as the function, structure and anatomy of the heart. In this review, we will give an overview of cardiac function in general followed by an assessment of left ventricular function using echocardiography with calculation of cardiac output, left ventricular ejection fraction (EF), fractional shortening, fractional area contraction, M mode EF, 2D planimetry and 3D volumetry. We will briefly discuss mitral annulus post systolic excursion (MAPSE), calculation of dP/dt, speckle tracking or eyeballing to estimate EF for the experienced user. In a following section, we will discuss how to assess cardiac preload and diastolic function in 4 simple steps. The first step is the assessment of systolic function. The next step assesses the left atrium. The third step evaluates the diastolic flow patterns and E/e' ratio. The final step integrates the information of the previous steps. Echocardiography is also the perfect tool to evaluate right ventricular function with tricuspid annular plane systolic excursion (TAPSE), tissue Doppler imaging, together with inferior vena cava dimensions and systolic pulmonary artery pressure and right ventricular systolic pressure measurement. Finally, methods to assess fluid responsiveness with echocardiography are discussed with the inferior vena cava collapsibility index and the variation on left ventricle outflow tract peak velocity and velocity time integral. Cardiac ultrasonography is an indispensible tool for the critical care physician to assess cardiac preload, afterload and contractile function in hemodynamically unstable patients in order to fine-tune treatment with fluids, inotropes and/or vasopressors.

Transcranial Doppler ultrasound in therapeutic hypothermia for children after resuscitation

Aim of the studyThe aim of the present study was to assess the cerebral flow in children receiving therapeutic hypothermia after resuscitation. The prognostic value of transcranial Doppler findings was correlated with the clinical outcomes in these children. MethodsA retrospective cohort study was conducted at the paediatric intensive care unit of Chang Gung Children's Hospital between January 2011 and December 2012. All children from 1 month to 18 years of age who received therapeutic hypothermia after resuscitation were eligible. Serial transcranial Doppler examinations were performed and the findings were reviewed. ResultsSeventeen children met the eligibility criteria for this study. Fourteen patients (82.3%) were asphyxial in aetiology, and 12 (70.5%) of these cases occurred outside of the hospital. Eight patients (47.1%) had a Paediatric Cerebral Performance Score of 1 or 2 at 3 months after the events. Reversal diastolic or undetectable flow patterns during therapeutic hypothermia were associated with unfavourable prognosis. Normal mean flow velocity in the rewarming phase and normal pulsatility index in the hypothermia and rewarming phases were associated with favourable outcome. ConclusionThe transcranial Doppler examinations provided additional information for cerebral perfusion during therapeutic hypothermia, which may in the future be used to guide changes to hypothermia management. Mean cerebral blood flow velocity and pulsatility index by transcranial Doppler sonography can serve as a prognostic factor for children who receive therapeutic hypothermia after resuscitation.

The Evaluation of Type 2 Diabetes Mellitus Related Changes in Diastolic Dysfunction During Exercise Using Conventional and Tissue Doppler Echocardiography.

BackgroundThe aim of this study was to evaluate the relationship between changes in diastolic functions during exercise and the exercising capacity in diabetic patients with diastolic dysfunction and to compare them with healthy individuals and diabetic patients without diastolic dysfunction.MethodsTotally 70 patients prospectively were included in the study and three groups were formed. Forty-six diabetic patients were divided into two groups: those with (group 1) and without (group 2) diastolic dysfunction. The control group (group 3) consisted of 24 patients. All patients were subjected to treadmill exercising test. Echocardiographical assessment was made before exercise and immediately after peak exercise.ResultsExercising time was dramatically decreased in group 1 compared to the other groups (group 1: 396 ± 125 second, group 2: 487 ± 66 second and group 3: 519 ± 102 second). In group 1, the diastolic mitral flow pattern at rest was transformed into pseudo-normal pattern at peak exercise from abnormal relaxation pattern (E/A ratio 0.70 ± 0.11 during rest, 1.02 ± 0.16; P < 0.0001 during peak exercise). Deceleration time (DT) and iso-volumetric relaxation time (IVRT) turned to normal values (DT 238.86 ± 39.48 millisecond during rest and 199.5 ± 23.57 millisecond during peak exercise; P = 0.001, IVRT 102.83 ± 16.22 millisecond during rest and 74.36 ± 8.67 millisecond during peak exercise; P = 0.001). In groups 2 and 3, the mitral flow pattern, DT and IVRT remained within normal limits during rest and exercise. E/Em ratio, which is one of the parameters of tissue Doppler, increased during peak exercise in the diabetic group with diastolic dysfunction (E/Em ratio 7.85 ± 3.31 during rest and 11.14 ± 3.40 after peak exercise; P < 0.0001).ConclusionsDiabetic patients with diastolic dysfunction demonstrated a reduced exercise capacity, which may be due to aggravation of pre-existing left ventricular dysfunction.

The Interplay of Aging, Aortic Stiffness and Blood Viscosity in Atherogenesis

Normal aortic compliance allows cardiac output to be distributed throughout the cardiac cycle, resulting in lower peak blood velocity. Loss of compliance with aging, hypertension, and possibly other risk factors for atherosclerosis increases peak blood velocity, creating eddy currents in areas of changing vascular geometry, as well as creating adverse patterns of diastolic flow. In the resulting areas of low flow, increased blood viscosity creates the potential for thrombosis. Occlusive thrombi may cause death; parietal or mural thrombi may organize to form atherosclerotic plaques.

Effect of the mitral valve on diastolic flow patterns

The leaflets of the mitral valve interact with the mitral jet and significantly impact diastolic flow patterns, but the effect of mitral valve morphology and kinematics on diastolic flow and its implications for left ventricular function have not been clearly delineated. In the present study, we employ computational hemodynamic simulations to understand the effect of mitral valve leaflets on diastolic flow. A computational model of the left ventricle is constructed based on a high-resolution contrast computed-tomography scan, and a physiological inspired model of the mitral valve leaflets is synthesized from morphological and echocardiographic data. Simulations are performed with a diode type valve model as well as the physiological mitral valve model in order to delineate the effect of mitral-valve leaflets on the intraventricular flow. The study suggests that a normal physiological mitral valve promotes the formation of a circulatory (or “looped”) flow pattern in the ventricle. The mitral valve leaflets also increase the strength of the apical flow, thereby enhancing apical washout and mixing of ventricular blood. The implications of these findings on ventricular function as well as ventricular flow models are discussed.

Detection of Internal Thoracic Artery Dissection at Coronary Anastomosis Using Intraoperative 15-MHz High-Frequency Epicardial Ultrasound

A 66-year-old man with a history of diabetes mellitus presented with angina pectoris with 3-vessel disease, and he underwent off-pump coronary artery bypass grafting via median sternotomy. After performing bypass grafting of the left internal thoracic artery to the left anterior descending artery, the appearance of anastomosis configuration appeared to be acceptable. However, transit time flow measurement (TTFM) showed that the mean graft flow was 10 mL/min, which was less than expected despite an acceptable flow curve with a diastolic flow pattern, a pulsatility index (index of resistance) of 2.0, and diastolic filling (proportion of diastole with coronary flow) of 65% (Figure 1). In addition to TTFM, the …

Effect of diastolic flow patterns on the function of the left ventricle

Direct numerical simulations are used to study the effect of intraventricular flow patterns on the pumping efficiency and the blood mixing and transport characteristics of the left ventricle. The simulations employ a geometric model of the left ventricle which is derived from contrast computed tomography. A variety of diastolic flow conditions are generated for a fixed ejection fraction in order to delineate the effect of flow patterns on ventricular performance. The simulations indicate that the effect of intraventricular blood flow pattern on the pumping power is physiologically insignificant. However, diastolic flow patterns have a noticeable effect on the blood mixing as well as the residence time of blood cells in the ventricle. The implications of these findings on ventricular function are discussed.