Altered left ventricular geometry and torsional mechanics in high altitude-induced pulmonary hypertension:

Transcription

1 Altered left ventricular geometry and torsional mechanics in high altitude-induced pulmonary hypertension: a 3-D echocardiographic study B.W. De Boeck,* S. Kiencke, C. Dehnert, K. Auinger, # M. Maggiorini, # P.T. Buser,* B.A. Kaufmann* * University Hospital Basel, Basel-CH; Bruderholz Hospital, Basel-CH, University of Ulm, Ulm-DE, # University Hospital Zürich, Zürich-CH

2 Conflict of interests Toshiba Switzerland kindly provided the Artida ultrasound system and working station for the duration and sole purpose of the study. Financial support, grants, stock: none Speaker fees, consultant fees: none

3 Background

4 Torsion and LV Function double helix - torsion FS 5-20% EF 60% + deformable myofiber sheets Fiber cross-interactions Matrix deformation Amplification Trew M L et al. Exp Physiol. 2006;9:

5 LV twist and torsion Torque Arm LV LV Torsion Twist ( /cm) ( ) = = R 2 > R apical rotation - basal rotation base-apex distance subepicardium subendocardium 2, , , ,5-4 LV Twist LV Torsion apical rotation mid rotation basal rotation Subepicardium: left hand helix (R 2 ) Subendocardium: right hand helix, (R ) Basal level: clockwise rotation (-) Apical level: counterclockwise rotation (+) figure source: P. Sengupta et al. JACC Img. 2008

6 Determinants of twist and torsion Imaging-related variability (patho-)physiologic factors variable LV length: General myofibre mechanics: inter-subject variability torsion? R 2 R R Preload ( ) & Afterload ( ) Contractilty ( ) variable scan planes: Epi- vs Endo torque ratio: rotation = level dependent true apical? conc. remodeling = R 2 >> R specific endo- or epi- disease LV geometry, RV pressure? eccentricity (D-shaping) pulmonary pressure sfericity 2 B. van Dalen et al. JASE 2008 S. Puwanant, JD Thomas et al. Circulation B. van Dalen et al. J Appl Physiol 200

7 PAP - geometry - torsion? chronic pulmonary hypertension "irreversible" increase in pulmonary artery pressure (PAP) is associated with geometrical changes and reduced LV Torsion at unchanged LVEF compared to control group. many baseline differences chronic = multiple potential mechanisms altitude-induced pulmonary hypertension "acute and reversible" increase in PAP within same individual paired comparison acute = no structural remodelling yet AIM: to study the relation PAP-geometry-LV torsion S. Puwanant, JD Thomas et al. Circulation 200

8 Methods

9 Study design: low and high altitude Basel Basel: Echo core-lab Zürich Zürich: baseline (n=26) Margherita Margherita 4459m Monte Rosa: altitude (n=22) D0 3600m D Altitude Echo at D3 and D4

10 general study parameters O 2 - Circulation Arterial Oxygen pulse oxymetre Saturation (SatO 2 ) Circulation Heart rate / Cardiac Index (CI) from 3-D stroke volume RV function / loading RV volumes 2-D areas in AP4Ch (RV EDA / RV ESA) RV function 2-D fractional area change (RV FAC) RV preload VCI size+variation & RV EDA RV afterload s/d PAP by TV/PV regurgitation gradient (TR- / PR-PG) LV function / loading LV volumes 3-D volumes (LV ESV / LV EDV) LV function 3-D ejection fraction (LV-EF) LV strains 3-D speckle tracking derived strains and torsion LV preload transmitral E / mean annular TDI Ea (E/Ea) & LV-EDV LV afterload invasive blood pressure (sys / dias BP) Toshiba Artida ultrasound system and working station kindly provided by Toshiba Switzerland

11 3-D deformation Alignment of axes (as in CMR) - true 2-Ch (0 to IVS) long axis - mod. 4-Ch (90 to 2-Ch) - 3 SAX (evenly distributed, 90 to long axis) Automated 3-D speckle tracking - Strains (circum., long., radial) - rotation, twist, torsion - LV EF and LV volumes

12 SAX base SAX mid SAX apex 3-D geometry Alignment of axes (as in CMR) - true 2-Ch (0 to IVS) long axis - mod. 4-Ch (90 to 2-Ch) - 3 SAX (evenly distributed, 90 to long axis) Automated 3-D speckle tracking - Strains (circum., long., radial) - rotation, twist, torsion - LV EF and LV volumes definition of LV geometry, both diastolic / systolic LV eccentricity mod. 4-Ch true 2-Ch LV sphericity Areas: 2Ch / 4Ch Volume / length (ml/cm) D sept-lat D ant-inf

13 Results

14 Haemodynamics & Loading O 2 - Circulation p< SatO 2 (%) D3 p<0.0 D4 2,6 2,2,8,4 CI (l/min/m 2 ) D3 D4

15 Haemodynamics & Loading O 2 - Circulation p< Heart rate (bpm) D3 p<0.0 D4 2,6 2,2,8,4 CI (l/min/m 2 ) D3 D4

16 Haemodynamics & Loading O 2 - Circulation p<0.0 Heart rate (bpm) D3 D Afterload p<0.0 PAP (mmhg) D3 D LV Preload p=ns E / Ea Ratio D3 D4 3 p< p=ns 2, ,2 0 p=ns 0, ,4 CI (l/min/m 2 ) D3 D systemic BP (mmhg) D3 D ED Volume (ml) D3 D4

17 LV- & RV- function D3 D4 RV EDA (cm 2 ) 20 ± ± ± 4.6 RV ESA (cm 2 ) ± ± 3.0 # 2 ± 2.9 RV FAC (%) 46 ± ± ± 9.0 LV EDV (ml) 7 ± 22 4 ± 27 8 ± 22 LV ESV (ml) 50 ± 50 ± 5 49 ± 2 LV SV (ml) 67 ± 3 64 ± 3 69 ± 3* LV EF (%) 57 ± ± ± 5.2 Strain Circum. (%) ± ± ± 4.6 Strain Longit. (%) -6.0 ± ± ± 2. Strain Radial (%) 34.8 ± ± ± 6.7 # p<0.0 vs low altitude, p<0.05 vs low altitude, * p<0.05 high altitude D3 vs D4. All p-values corrected for multiple repeated measurements.

18 LV Geometry & Torsion LV Sfericity (ml/cm) p=ns D3 D4,2, p<0.05 p<0.05 LV Eccentricity,2, p<0.05 p< ,9 0,9 0 diastolic systolic 0,8 diastolic 0,8 systolic 8 LV Twist ( o ) p=0.09 p<0.05 D3 3 LV torsion ( o /cm) p<0.05 p= p<0.0 D4 2,5 p< , ,5 0 0

19 Torsion ( 0 /cm) Torsion changes ( 0 /cm) Geometry vs Torsion Torsion ( 0 /cm) Torsion Changes ( 0 /cm) Diastolic Eccentricity R = p< Systolic Eccentricity R = p< ,85 0,95,05,5,25, R = p= , - 0 0, 0,2 0,3-4 Diastolic Eccentricity Changes 0 0,85 0,95,05,5,25, R = p= , - 0 0, 0,2 0,3-4 Systolic Eccentricity Changes

20 Conclusions

21 Conclusions High altitude exposure is associated with pulmonary hypertension, mild D-shaping of the ventricle and reduced ventricular torsion without changes in global left ventricular function and preload. (changes in ) torsion only correlated with (changes in) ventricular eccentricity Taken together, these data suggests a direct relation between LV geometry and torsional mechanics.

22 3-D speckle tracking 3D instead of 2D speckle tracking - geometry assumption free (LV mass / volume) - through plane tracking - distance apex-base standardized twist torsion - standardized alignment / planes Disadvantages - image quality - frame rate (9 Hz) global strains / torsion limited to ejection / peak Toshiba Artida 3-D Acquisition + 3-D tracking software

23 Thank You for Your Attention