Ventricular Mechanics

Ventricular Mechanics   < Ventricular structure >   The myocytes are mechanically coupled together, -> through the fibrous elements of the extracelluar matrix(ECM).   ECM의 구성 strands of collagen fibronectin other long-chain proteins -> tie the myocytes together at a hierarchy scales -> 심장의 passive stiffness 제공한다.   ECM은 fibroblast에서 만들어진다. -> 심장의 mechanical loading에 의하여 조절되고, -> 심부전의 진행에 한 역할을 한다.   ECM invests the myocytes in a complex weave and helps define the fiber and sheet architecture of the heart wall.   Primary organization Myocytes는 intercalated discs를 통해서 end to end로 서로 단단히 결합된다. -> 전기적 흥분이 이 connections를 통해 전도된다. -> worven sort of sturcture 이룬다. -> further tied together into bundle-like fibers   Secondary organization fibers into sheets (a few cell layers thick) -> woven sort 구성 (by a consistent pattern of organization) -> a greater ease of shearing along the plane of the sheets   Specialized conducting network SA node -> AV node -> bundle of His -> Purkinje fibers   RV & LV   Valves -> inlet : the AV valves (mitrial & tricuspid) outlet : the semilunar valves (aortic & pulmonary) -> papillary mm. chodae tendineae fibrous rings  <img src="https://t1.daumcdn.net/cfile/cafe/2050F30F4BB2C56359" class="tx-daum-image" style="CLEAR: none; FLOAT: none" actualwidth="329" hspace="1" width="329" vspace="1" border="0" id="A_2050F30F4BB2C5635994D4"/>    The RV differs from the LV in having a longer tubular section of outflow tract, the infundibulum, below the pulmonary valve.   The "wind-kessel" effect -> systolic 때 신축성있는 대혈관이 확장되어 flow를 원활히 한다.   Pericardium double-layered fibrous sac flaxible, but not stretchy     < Basic Continuum Mechanics Review >   "Continum" : a smooth, locally homogeneous material : continum mechanics of the heart/blood (심장과 혈액의 메카니즘을 “연속체”의 개념으로 보기로 한다.)   “Stress" : the force acting on a surface, divided by the area of the surface : Normal stress - 표면에 수직으로 작용하는 stress : Shear(전단) stress - 표면에 비스듬이 작용하는 stress : Stress tensor - higher order quantity than a vector   “Strain” : the corresponding resulting deformation of the material (also caraterized by tensor quantity) : "한쪽에서 수축하면 한쪽에서는 이완된다.” : the principal strains - direction을 따라 있는 strain   "In general, the angle between two material line elements within the tissue will change due to the deformation of the material, reflecting local shear."   심장을 pressurized blood로 둘러싸인 thin curved membrane으로 가정하면, "LaPlace law" : curved membrane을 가로지르는(across) force balanc의 의미 -> 어떤 장소에서 membrane 사이의 압력차의 균형을 조절하는데 필요한 wall tension은 그 membrane의 principal curvature에 따라 달렸다. : <?xml:namespace prefix = v /><v:shapetype id=_x0000_t75 stroked="f" filled="f" path="m@4@5l@4@11@9@11@9@5xe" o:preferrelative="t" o:spt="75" coordsize="21600,21600"><v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><v:path o:connecttype="rect" gradientshapeok="t" o:extrusionok="f"></v:path><?xml:namespace prefix = o /><o:lock aspectratio="t" v:ext="edit"></o:lock></v:shapetype><v:shape id=_x35108320 style="WIDTH: 78pt; HEIGHT: 26.54pt; v-text-anchor: top" type="#_x0000_t75"><v:imagedata src="file:///C:\DOCUME~1\KNUH\LOCALS~1\Temp\DRW000014701894.gif" o:title="DRW000014701894"></v:imagedata><?xml:namespace prefix = w /><w:wrap type="topAndBottom"></w:wrap></v:shape> (r1,r2 -> the greatest & the least(principal) radii of curvature of the membrane) (T1,T2 -> the tensions in the membrane along the corresponding directions) : 압력차가 높으면 tension이 커지고, curvature의 반지름(radius)이 작으면 tension이 작아진다. : 또다른 modifying factor는 external loading이 없는 상태에서 심근에 남아있는 residual forces다. -> helping restore the heart to its expanded state during diastole   Motion of continuous material 1) the Lagrangian approach : the motion of individual material points : relative to a reference configuration such as at end diastole : useful for discribing the deformation of solid materials (the muscle of the heart wall)   2) the Eulerian approach : the motion of material passing through fixed locations in space : useful for descfibing the flow of fluids -> such as the distribution of the velocity of the blood within the ventricular chambers   The Stiffness of heart : matrix의 개념 (complex quantity, rather than simple scalar quantity) : non-uniformity, anisotropy -> differernt degrees of stiffness in different direction : non-linearity -> not simply proportional to a deformation : viscoelastic material properties -> "stress relaxation"   Force generation : the active contraction of the myocytes -> interaction of the contractile proteins : the compression of the blood -> a rise in pressure that pushes outward : residual forces -> restore it to its end-diastolic configuration : residual stress -> the tendency of the heart wall to spring open : 혈액의 압력에 상관없이 심근은 돌아오려는 성질 있다. : 일반적으로 fiber의 local direction으로 수축하는 성질. -> subendocardium과 subepicardium의 oblique direction 영향(+) (but, there is also a significant component of cross-fiber shortening during systole in the subendocardium.)   Fluid flow : 높은 압력에서 낮은 압력으로 가려는 성향. : internal forces due to the viscosity of the fluid in the presence of shears or gradients in velocity(the viscous forces act to oppose and reduce such shears), as well as external forces such as gravity. : flow가 증가/감소함에 따라 velocity가 이에 상응하여 감소/증가. -> flow의 volume rate는 보존된다. : the continuity equation -> <v:shapetype id=_x0000_t75 stroked="f" filled="f" path="m@4@5l@4@11@9@11@9@5xe" o:preferrelative="t" o:spt="75" coordsize="21600,21600"><v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><v:path o:connecttype="rect" gradientshapeok="t" o:extrusionok="f"></v:path><o:lock aspectratio="t" v:ext="edit"></o:lock></v:shapetype><v:shape id=_x35177328 style="WIDTH: 46.75pt; HEIGHT: 9.75pt; v-text-anchor: top" type="#_x0000_t75"><v:imagedata src="file:///C:\DOCUME~1\KNUH\LOCALS~1\Temp\DRW000014701896.gif" o:title="DRW000014701896"></v:imagedata><w:wrap type="topAndBottom"></w:wrap></v:shape>(v : velocity vector) : Navier-Stokes equation -> 심실을 드나드는 blood의 양은 local volume of the wall의 변화로 나타난다. -> blood의 움직임은 int. forces와 ext. forces의 조합에 따라 결정. -> no slip of the blood relative to the surface of the endocardium : Bernoulli equation -> <v:shapetype id=_x0000_t75 stroked="f" filled="f" path="m@4@5l@4@11@9@11@9@5xe" o:preferrelative="t" o:spt="75" coordsize="21600,21600"><v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><v:path o:connecttype="rect" gradientshapeok="t" o:extrusionok="f"></v:path><o:lock aspectratio="t" v:ext="edit"></o:lock></v:shapetype><v:shape id=_x35285664 style="WIDTH: 107.25pt; HEIGHT: 22.5pt; v-text-anchor: top" type="#_x0000_t75"><v:imagedata src="file:///C:\DOCUME~1\KNUH\LOCALS~1\Temp\DRW000014701898.gif" o:title="DRW000014701898"></v:imagedata><w:wrap type="topAndBottom"></w:wrap></v:shape> (p : pressure v : velocity) -> conservation of energy in the flowing fluid => velocity 변화에 따른 운동에너지의 변화는 오로지 pressure gradients의 가속에 의한다. : modified Bernoulli formula -> <v:shapetype id=_x0000_t75 stroked="f" filled="f" path="m@4@5l@4@11@9@11@9@5xe" o:preferrelative="t" o:spt="75" coordsize="21600,21600"><v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><v:path o:connecttype="rect" gradientshapeok="t" o:extrusionok="f"></v:path><o:lock aspectratio="t" v:ext="edit"></o:lock></v:shapetype><v:shape id=_x35373560 style="WIDTH: 33.6pt; HEIGHT: 11.75pt; v-text-anchor: top" type="#_x0000_t75"><v:imagedata src="file:///C:\DOCUME~1\KNUH\LOCALS~1\Temp\DRW00001470189a.gif" o:title="DRW00001470189a"></v:imagedata><w:wrap type="topAndBottom"></w:wrap></v:shape> (v : the magnitude of the peak velocity in the jet in m/s p : the pressure drop in mmHg) : Reynolds number -> the ratio of the convective flow inertia(관성) to the shear force -> <v:shapetype id=_x0000_t75 stroked="f" filled="f" path="m@4@5l@4@11@9@11@9@5xe" o:preferrelative="t" o:spt="75" coordsize="21600,21600"><v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><v:path o:connecttype="rect" gradientshapeok="t" o:extrusionok="f"></v:path><o:lock aspectratio="t" v:ext="edit"></o:lock></v:shapetype><v:shape id=_x35327752 style="WIDTH: 79.7pt; HEIGHT: 22.5pt; v-text-anchor: top" type="#_x0000_t75"><v:imagedata src="file:///C:\DOCUME~1\KNUH\LOCALS~1\Temp\DRW00001470189c.gif" o:title="DRW00001470189c"></v:imagedata><w:wrap type="topAndBottom"></w:wrap></v:shape> (V : characteristic velocity of the flow L : characteristic length of the region p : density <v:shapetype id=_x0000_t75 stroked="f" filled="f" path="m@4@5l@4@11@9@11@9@5xe" o:preferrelative="t" o:spt="75" coordsize="21600,21600"><v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><v:path o:connecttype="rect" gradientshapeok="t" o:extrusionok="f"></v:path><o:lock aspectratio="t" v:ext="edit"></o:lock></v:shapetype><v:shape id=_x35652280 style="WIDTH: 6pt; HEIGHT: 9.75pt; v-text-anchor: top" type="#_x0000_t75"><v:imagedata src="file:///C:\DOCUME~1\KNUH\LOCALS~1\Temp\DRW00001470189e.gif" o:title="DRW00001470189e"></v:imagedata><w:wrap type="topAndBottom"></w:wrap></v:shape>: coefficient of viscosity <v:shapetype id=_x0000_t75 stroked="f" filled="f" path="m@4@5l@4@11@9@11@9@5xe" o:preferrelative="t" o:spt="75" coordsize="21600,21600"><v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><v:path o:connecttype="rect" gradientshapeok="t" o:extrusionok="f"></v:path><o:lock aspectratio="t" v:ext="edit"></o:lock></v:shapetype><v:shape id=_x35658792 style="WIDTH: 5.25pt; HEIGHT: 9.75pt; v-text-anchor: top" type="#_x0000_t75"><v:imagedata src="file:///C:\DOCUME~1\KNUH\LOCALS~1\Temp\DRW0000147018a0.gif" o:title="DRW0000147018a0"></v:imagedata><w:wrap type="topAndBottom"></w:wrap></v:shape>: kinematic viscosity) : Womersley number (-> for pulsatile flow) -> the ratio of the oscillatory inertia force to the shear forces -> <v:shapetype id=_x0000_t75 stroked="f" filled="f" path="m@4@5l@4@11@9@11@9@5xe" o:preferrelative="t" o:spt="75" coordsize="21600,21600"><v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><v:path o:connecttype="rect" gradientshapeok="t" o:extrusionok="f"></v:path><o:lock aspectratio="t" v:ext="edit"></o:lock></v:shapetype><v:shape id=_x12779872 style="WIDTH: 50.6pt; 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HEIGHT: 9.75pt; v-text-anchor: top" type="#_x0000_t75"><v:imagedata src="file:///C:\DOCUME~1\KNUH\LOCALS~1\Temp\DRW0000147018a4.gif" o:title="DRW0000147018a4"></v:imagedata><w:wrap type="topAndBottom"></w:wrap></v:shape>: characteristic frequency of the pulsation   < Cardiac Cycle >    <img src="https://t1.daumcdn.net/cfile/cafe/1542590F4BB2C57867" class="tx-daum-image" style="CLEAR: none; FLOAT: none" actualwidth="271" hspace="1" width="271" vspace="1" border="0" id="A_1542590F4BB2C578676B2A"/>    Force generation : 골격근의 수축과 달리, 심장근의 수축은 cardiac conduction system의 exciting impulse에 의한다. (by depolarization of an adjacent muscle cell)   4 principal filling mechanisms 1) elastic recoil of myocardium 2) 심근수축에 의한 동맥압력증가 -> 확장기 때 심근으로 이동 3) 이완기 심장으로 흐르는 blood -> erectile effect of the wall 4) 심실이와기 끝무렵에 일어나는 심방수축 -> 심실의 final filling을 돕는다.   RV와 LV의 상호작용 -> LV dysfunction으로 인한 폐혈관압력증가 => RV에 load 증가시킨다. -> Respiratory effects : 흡기 -> 흉곽내 압력 감소 (RV로의 venous return 증가, LV로의 return은 감소) : 호기 -> 흉곽내 압력 증가   Feedback & regulatory mechanisms   Humoral(hormonal) influences : Epinephrine -> SA note에 작용하여 심박수 늘린다. -> 여러 장기의 arteriolar tone 증가 : ANP : Steroid : 임신 : 자율신경계   Afterload의 변화   수축력의 변화   임신과 출산     < Function Measures >   Ejection Fraction = <v:shapetype id=_x0000_t75 stroked="f" filled="f" path="m@4@5l@4@11@9@11@9@5xe" o:preferrelative="t" o:spt="75" coordsize="21600,21600"><v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><v:path o:connecttype="rect" gradientshapeok="t" o:extrusionok="f"></v:path><o:lock aspectratio="t" v:ext="edit"></o:lock></v:shapetype><v:shape id=_x35247176 style="WIDTH: 98pt; HEIGHT: 23pt; v-text-anchor: top" type="#_x0000_t75"><v:imagedata src="file:///C:\DOCUME~1\KNUH\LOCALS~1\Temp\DRW0000147018a6.gif" o:title="DRW0000147018a6"></v:imagedata><w:wrap type="topAndBottom"></w:wrap></v:shape> = <v:shapetype id=_x0000_t75 stroked="f" filled="f" path="m@4@5l@4@11@9@11@9@5xe" o:preferrelative="t" o:spt="75" coordsize="21600,21600"><v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><v:path o:connecttype="rect" gradientshapeok="t" o:extrusionok="f"></v:path><o:lock aspectratio="t" v:ext="edit"></o:lock></v:shapetype><v:shape id=_x35824216 style="WIDTH: 217.5pt; HEIGHT: 23pt; v-text-anchor: top" type="#_x0000_t75"><v:imagedata src="file:///C:\DOCUME~1\KNUH\LOCALS~1\Temp\DRW0000147018a8.gif" o:title="DRW0000147018a8"></v:imagedata><w:wrap type="topAndBottom"></w:wrap></v:shape> CO = (SV)(HR)   Cardiac Index = CO / BSA   " In particular, the rates of early ejection from and early filling of the ventricle can be used as measures of the contractility and stiffness of the ventricle,"   Pressures in the blood   Peripheral resistance   Myocardial mass   Measurement methods (noninvasive & invasive catheter-based approaches) 1) Projection nuclear imaging with radioisotope-labeld red cells 2) Tomographic imaging - Echocardiography - SPECT or PET - MRI - CT   Invasive catheter-based methods pressure-measuring catheter catheters with ultrasound transducers thermodilution catheters conductance catheters   MR 1) Magnetization tagging - SPAMM 2) Phase shift   Stain : cannot be descriged by a vector -> but must be described with a tensor     < Mechanical Effects of Disease >   Cardiac hypertrophy 1) Concentric thickening - increased pressure demand : 더 큰 압력을 생성한다.(<- 세포에 더 많은 contractile elements) : the force/unit thickness of wall -> 정상심장과 비슷 : but fibrosis 생기면, -> stiffness 증가, diastolic filling 감소 -> 산소와 영양분의 이동길이 늘어남. => ischemia의 위험성 증가. 2) Eccentric thickening - increased volume to be pumped : (같은 압력에도) 더 큰 tension을 생성한다. : increased demand -> progressive dysfunction “두 경우 모두 myocytes의 덩치는 커지지만, 그 숫자가 늘지는 않는다.”   Ischemia & infarction   Pulmonary Hypertension   Valve disease 1) Stenosis - concentric hypertrophy 2) Insufficiency - eccentric hypertrophy : turbulence : shunts   Cadiomyopathies : 많은 경우 idiopathic : preload 증가 -> greater demand : Restrictive cardiomyopathies : Hypertrophic cardiomyopathies -> muscle fiber의 장애, fibrosis => contraction efficiency 감소   Pericardium : inflammation -> stiffened pericardium => abrupt cessation of diastolic filling : pericardial effusion   Pneumothorax : venous return의 장애 -> cardiac output 감소 : tension pneumothorax -> positive intrathoracic pressure   Pulmonary embolism : pulmonary outflow의 장애 -> 좌심으로의 inflow 감소 : acute -> 우심실 load의 증가 : chronic -> 2ndary pulmonary hypertension & RV hypertrophy     Rhythm disturbances