| 1. |
- Calcutteea, Avin, 1978-
(författare)
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New insights in the assessment of right ventricular function : an echocardiographic study
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: The right ventricle (RV) is multi-compartmental in orientation with a complex structural geometry. However, assessment of this part of the heart has remained an elusive clinical challenge. As a matter of fact, its importance has been underestimated in the past, especially its role as a determinant of cardiac symptoms, exercise capacity in chronic heart failure and survival in patients with valvular disease of the left heart. Evidence also exists that pulmonary hypertension (PH) affects primarily the right ventricular function. On the other hand, previous literature suggested that severe aortic stenosis (AS) affects left ventricular (LV) structure and function which partially recover after aortic valve replacement (AVR). However, the impact of that on RV global and segmental function remains undetermined. Objectives: We sought to gain more insight into the RV physiology using 3D technology, Speckle tracking as well as already applicable echocardiographic measures. Our first aim was to assess the normal differential function of the RV inflow tract (IT), apical and outflow tract (OT) compartments, also their interrelations and the response to pulmonary hypertension. We also investigated the extent of RV dysfunction in severe AS and its response to AVR. Lastly, we studied the extent of global and regional right ventricular dysfunction in patients with pulmonary hypertension of different aetiologies and normal LV function.Methods: The studies were performed on three different groups; (1) left sided heart failure with (Group 1) and without (Group 2) secondary pulmonary hypertension, (2) severe aortic stenosis and six months post AVR and (3) pulmonary hypertension of different aetiologies and normal left ventricular function. We used 3D, speckle tracking echocardiography and conventionally available Doppler echocardiographic transthoracic techniques including M-mode, 2D and myocardial tissue Doppler. All patients’ measurements were compared with healthy subjects (controls). Statistics were performed using a commercially available SPSS software.Results:1- Our RV 3D tripartite model was validated with 2D measures and eventually showed strong correlations between RV inflow diameter (2D) and end diastolic volume (3D) (r=0.69, p<0.001) and between tricuspid annular systolic excursion (TAPSE) and RV ejection fraction (3D) (r=0.71, p<0.001). In patients (group 1 & 2) we found that the apical ejection fraction (EF) was less than the inflow and outflow (controls: p<0.01 & p<0.01, Group 1: p<0.05 & p<0.01 and Group 2: p<0.05 & p<0.01, respectively). Ejection fraction (EF) was reduced in both patient groups (p<0.05 for all compartments). Whilst in controls, the inflow compartment reached the minimum volume 20 ms before the outflow and apex, in Group 2 it was virtually simultaneous. Both patient groups showed prolonged isovolumic contraction (IVC) and relaxation (IVR) times (p<0.05 for all). Also, in controls, the outflow tract was the only compartment where the rate of volume fall correlated with the time to peak RV ejection (r = 0.62, p = 0.03). In Group 1, this relationship was lost and became with the inflow compartment (r = 0.61, p = 0.01). In Group 2, the highest correlation was with the apex (r=0.60, p<0.05), but not with the outflow tract.2- In patients with severe aortic stenosis, time to peak RV ejection correlated with the basal cavity segment (r = 0.72, p<0.001) but not with the RVOT. The same pattern of disturbance remained after 6 months of AVR (r = 0.71, p<0.001). In contrast to the pre-operative and post-operative patients, time to RV peak ejection correlated with the time to peak outflow tract strain rate (r = 0.7, p<0.001), but not with basal cavity function. Finally in patients, RVOT strain rate (SR) did not change after AVR but basal cavity SR fell (p=0.04).3- In patients with pulmonary hypertension of different aetiologies and normal LV function, RV inflow and outflow tracts were dilated (p<0.001 for both). Furthermore, TAPSE (p<0.001), inflow velocities (p<0.001), basal and mid-cavity strain rate (SR) and longitudinal displacement (p<0.001 for all) were all reduced. The time to peak systolic SR at basal, mid-cavity (p<0.001 for both) and RVOT (p=0.007) was short as was that to peak displacement (p<0.001 for all). The time to peak pulmonary ejection correlated with time to peak SR at RVOT (r=0.7, p<0.001) in controls, but with that of the mid cavity in patients (r=0.71, p<0.001). Finally, pulmonary ejection acceleration (PAc) was faster (p=0.001) and RV filling time shorter in patients (p=0.03) with respect to controls.Conclusion: RV has distinct features for the inflow, apical and outflow tract compartments, with different extent of contribution to the overall systolic function. In PH, RV becomes one dyssynchronous compartment which itself may have perpetual effect on overall cardiac dysfunction. In addition, critical aortic stenosis results in RV configuration changes with the inflow tract, rather than outflow tract, determining peak ejection. This pattern of disturbance remains six month after valve replacement, which confirms that once RV physiology is disturbed it does not fully recover. The findings of this study suggest an organised RV remodelling which might explain the known limited exercise capacity in such patients. Furthermore, in patients with PH of different aetiologies and normal LV function, there is a similar pattern of RV disturbance. Therefore, we can conclude that early identification of such changes might help in identifying patients who need more aggressive therapy early on in the disease process.
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| 2. |
- Gustafsson, Ulf, 1976-
(författare)
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Ventricular rotation and the rotation axis : a new concept in cardiac function
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: The twisting motion of the left ventricle (LV), with clockwise rotation at the base and counter clockwise rotation at the apex during systole, is a vital part of LV function. Even though LV rotation has been studied for decades, the rotation pattern has not been described in detail. By the introduction of speckle tracking echocardiography measuring rotation has become easy of access. However, the axis around which the LV rotates has never before been assessed. The aims of this thesis were to describe the rotation pattern of the LV in detail (study I), to assess RV apical rotation (study II), develop a method to assess the rotation axis (study III) and finally to study the effect of regional ischemia to the rotation pattern of the LV (study IV). Methods: Healthy humans were examined in study I-III and the final study populations were 40 (60±14 years), 14 (62±11 years) and 39 (57±16 years) subjects, respectively. In study IV six young pigs (32-40kg) were studied. Standard echocardiographic examinations were performed. In study IV the images were recorded before and 4 minutes after occlusion of left anterior descending coronary artery (LAD). Rotation was measured in short axis images by using a speckle tracking software. By development of custom software, the rotation axis of the LV was calculated at different levels in every image frame throughout the cardiac cycle. Results: Study I showed significant difference in rotation between basal and apical rotations, as well as significant differences between segments at basal and mid ventricular levels. The rotation pattern of the LV was associated with different phases of the cardiac cycle. Study II found significant difference in rotation between the LV and the RV. RV rotation was heterogeneous and bi-directional, creating a ´tightening belt action´ to reduce it circumference. Study III indicated that the new method could assess the rotation axis of the LV. The motion of the rotation axes in healthy humans displayed a physiological and consistent pattern. Study IV found a significant difference in the rotation pattern, between baseline and after LAD occlusion, by measuring the rotation axes, but not by conventional measurements of rotation. AV-plane displacement and wall motion score (WMS) were also significantly changed after inducing regional ischemia. Conclusion: There are normally large regional differences in LV rotation, which can be associated anatomy, activation pattern and cardiac phases, indicating its importance to LV function. In difference to the LV, the RV did not show any functional rotation. However, its heterogeneous circumferential motion could still be of importance to RV function and may in part be the result of ventricular interaction. The rotation axis of the LV can now be assessed by development of a new method, which gives a unique view of the rotation pattern. The quality measurements and results in healthy humans indicate that it has a potential clinical implication in identifying pathological rotation. This was supported by the experimental study showing that the rotation axis was more sensitive than traditional measurements of rotation and as sensitive as AV-plane displacement and WMS in detecting regional myocardial dysfunction.
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| 3. |
- Henein, Mark, 1960-
(författare)
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Left atrial function in health and disease
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Objectives of this thesis are:1) To study possible atrial interaction in patients with right and left ventricular outflow tract obstruction due to significant pulmonary (PS) and aortic valve stenosis (AS), respectively.2) To assess left atrial (LA) intrinsic myocardial function and its relationship to indirect measures of left ventricular (LV) filling pressures in patients with paroxysmal atrial fibrillation (PAF).3) To test the hypothesis that the LA function is affected in patients with pulmonary arterial hypertension (PAH).4) To test the hypothesis that raised LA pressure as shown by pulmonary capillary wedge pressure (PCWP) correlates with severity of LA intrinsic systolic function.We conducted 4 studies to achieve the objective sabove.Study IMethods:We studied 41 PS patients (age 36±10 year) and 41 AS patients (age 35 ± 12 year) and compared them with 27 controls (age 30 ± 7 year). RV and LV filling were recorded by conventional PW Doppler. Biventricular segmental function was studied using the PW tissue Doppler imaging (TDI) and M mode techniques.Results:The 2 patient groups had similar degree of ventricular outflow tract obstruction. In the pressureoverloaded ventricle, global systolic function was preserved but long axis function was impaired.Patients had higher peak late filling (Awave)and TDI late diastolic (a’) velocities recorded in the disease free ventricles despite having similar peak early filling velocities (E wave), E wave deceleration time and E/e’ ratios were not different from controls (p>0.05 for all). The accentuation of atrial activity (A wave) was moderately correlated with the degree of contra lateral ventricular outflow tract obstruction (p<0.001 for both).Conclusion:In the pressure overloaded ventricle long axis function is more sensitive than global function in revealing myocardial dysfunction. The increased contra lateral atrial systolic activity suggests an evidence for atrial interaction in the form of ‘Cross Talk’.Study IIMethods:Twentyfive PAF patients (age 68±7 year, 10 males) with Doppler signs of raised filling pressures were studied using speckle tracking echocardiography and compared with 21 controls. LA segmental longitudinal strain (S), strain rate (SR) and myocardial velocities during atrial systole were measured as were LA longitudinal and transverse diameters. Markers of LV filling pressures were E/A andE/e’.Results:LA longitudinal diameter was larger in patients (5.5±0.6 vs. 4.8±0.6cm,p<0.01) and global LAS and SR were reduced (p<0.05 for both) and correlated with E/A (r=0.52 and r=0.43, p<0.05 for both). LA segmental S and SR were uniformly reduced compared with controls (p<0.05 for all) and also correlated with E/A (p<0.05 for all). LA myocardial velocities (TDI) were highest at the annular level and lowest at the rear in both patients and controls (p<0.01 for all), with the absolute values at each level not different between groups. Myocardial velocities negatively correlated with E/A at the annular level only in patients (septal: r=0.52; lateral: r=0.62, p<0.01 for both).Conclusion:In PAF patients, LA systolic function is suppressed and is directly related to the raised filling pressures. While intrinsic global and segmental function can reproducibly be studied by S and SR, myocardial velocities reflect only regional motion. These findings provide a sound explanation to the known beneficial effect of vasodilators in PAF patients.Study IIIMethods:We studied LA size and reservoir function in 35 patients (age 63 ± 15 years, 16 male) with idiopathic PAH using speckle tracking echocardiography who also underwent right heart catheterization simultaneously to assess pulmonary artery systolic pressure, and compared them with 27 age and gender normal controls.Results:In PAH patients, LA longitudinal diameter was not different from controls but transverse diameter was reduced (3.0 ± 0.6 vs. 3.7 ± 0.5cm, p<0.001). LA lateral wall strain rate (SR) during LV systole (atrial reservoir function was reduced at annular (p<0.001) and mid cavity (p<0.01) levels as were septal segments (p<0.03, for both) compared to controls. Opposite to controls, the two LA walls responded differently to right heart pressures. Lateral SR inversely correlated with pulmonary artery systolic pressure (PASP) (annular: r=0.45, p<0.005 and midcavity: r=0.43, p<0.01), but not with right atrial pressure (RAP). In contrast, septal SR inversely correlated with RAP (annular: r=0.39, p=0.02 and midcavity: r=0.38, p=0.03) but not with PASP.Conclusion:In patients with PAH, LA reservoir function is significantly impaired showing reduced myocardial strain rate properties. In addition,segmental function differs in their response to raised right heart pressures with the septal wall related to right atrial pressure and lateral wall related to the PASP. These findings suggest an evidence for atrial interaction in PAH, which is likely to have significant impact on LV performance.Study IVMethods:We studied 46 patients, mean age 61 ± 13 years, 17 males, of various etiologies with exertional breathlessness who underwent right heart catheterization and simultaneous transthoracic Doppler echocardiography using spectral, tissue Doppler and speckle tracking echocardiography techniques for assessing LA structure and function.Results:PCWP correlated with direct measurements of LA structure and function: LA volume (r= 0.43, p<0.01), LA global systolic strain rate (r=0.79, p<0.001) and to a lesser extent with LA systolic filling fraction (r=0.52, p<0.001). PCWP also correlated with indirect measures of LA pressure: LV E/A (r=0.66, p<0.001), E wave deceleration time (r=0.54, p<0.001), lateral E/e’ (r=0.49, p<0.001) and LV isovolumic relaxation time (r=0.36, p<0.01). LA strain rate was 78% sensitive and 84% specific in identifying patients with PCWP>15 mmHg, having accurately predicted PCWP in 63% of the cases.Conclusion:PCWP correlates with LA intrinsic systolic function and to a much lesser degree with indirect Doppler measures of raised LV filling pressures. These findings should have significant clinical implications in identifying breathless patients with raised LA pressure.
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| 4. |
- Zhao, Ying, 1975-
(författare)
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Effect of valve replacement for aortic stenosis on ventricular function
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background：Aortic stenosis (AS) is the commonest valve disease in the West. Aortic valve replacement (AVR) remains the only available management for AS and results in improved symptoms and recovery of ventricular functions. In addition, it is well known that AVR results in disruption of LV function mainly in the form of reversal of septal motion as well as depression of right ventricular (RV) systolic function. The aim of this thesis was to study, in detail, the early and mid-term response of ventricular function to AVR procedures (surgical and TAVI) as well as post operative patients’ exercise capacity. Methods：We studied LV and RV function by Doppler echocardiography and speckle tracking echocardiography (STE) in the following 4 groups; (1) 30 severe AS patients (age 62±11 years, 19 male) with normal LV ejection fraction (EF) who underwent AVR, (2) 20 severe AS patients (age 79±6 years, 14 male) who underwent TAVI, (3) 30 healthy controls (age 63±11 years, 16 male), (4) 21 healthy controls (age 57±9 years, 14 male) who underwent exercise echocardiography. Results: After one week of TAVI, the septal radial motion and RV tricuspid annulus peak systolic excursion (TAPSE) were not different from before, while surgical AVR had significantly reversed septal radial motion and TAPSE dropped by 70% compared to before. The extent of the reversed septal motion correlated with that of TAPSE (r=0.78, p<0.001) in the patients as a whole after AVR and TAVI (Study I). Compared with controls, the LV twist function was increased in AS patients before and normalized after 6 months of surgical AVR. In controls, the LV twist correlated with LV fractional shortening (r=0.81, p<0.001), a relationship which became weak in patients before (r=0.52, p<0.01) and after AVR (r=0.34, p=ns) (Study II). After 6 months of surgical AVR, the reversed septal radial motion was still significantly lower than before. The septal peak displacement also decreased and its time became prolonged. In contrast, the LV lateral wall peak displacement increased and the time to peak displacement was early. The accentuated lateral wall peak displacement correlated with the septal peak displacement time delay (r=0.60, p<0.001) and septal-lateral time delay (r=0.64, p<0.001) (Study III). In 21 surgical AVR patients who performed exercise echocardiography, the LV function was normal at rest but different from controls with exercise. At peak exercise, oxygen consumption (pVO2) was lower in patients than controls. Although patients could achieve cardiac output (CO) and heart rate (HR) similar to controls at peak exercise, the LV systolic and early diastolic myocardial velocities and strain rate as well as their delta changes were significantly lower than controls. pVO2 correlated with peak exercise LV myocardial function in the patients group only, and the systolic global longitudinal strain rate (GLSRs) at peak exercise was the only independent predictor of pVO2 in multivariate regression analysis (p=0.03) (Study IV). Conclusion: Surgical AVR is an effective treatment for AS patients, but results in reversed septal radial motion and reduced TAPSE. The newly developed TAVI procedure maintains RV function which results in preservation of septal radial motion. In AS, the LV twist function is exaggerated, normalizes after AVR but loses its relationship with basal LV function. While the reversed septal motion results in decreased and delayed septal longitudinal displacement which is compensated for by the accentuated lateral wall displacement and the time early. These patients remain suffering from limited exercise capacity years after AVR.
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