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Posts Tagged ‘right ventricle’

Right ventricle . . . more intelligent than Left ?

Posted in acute pulmonary embolism, Cardiac MRI, cardiac physiology, cardiac volume, Cardiology -Hemodynamics, Cardiology -unresolved questions, echocardiography, myocardial disease, pulmonary hypertension, Right ventricle, tagged , , , , , , , , , , , , , , on July 20, 2014| Leave a Comment »

The right ventricle  is considered as a docile cardiac chamber with passive filling and  emptying  properties .

This belief  was reinforced when Fontan  in early 1970s suggested a principle in the management of  cyanotic heart disease  when  the right side of the heart is underdeveloped. He  proved  RV can be by-passed safely , with  great veins  (IVC/SVC)  by  themselves  take care of filling the pulmonary circulation  without the need of RV pumping function.

While it is true for few complex cyanotic heart disease, largely this a misleading  concept. In clinical cardiology practice  ,sudden or non sudden  RV deaths happen every day in the form of . . .

  • RV Infarction
  • Acute RV dysfunction in massive pulmonary embolism
  • COPD with RV dysfunction
  • Most cases dilated cardiomypathy  the terminal event is due to RV  failure.

So , RV function can never be dispensable in day to day cardiac hemodynamics.

RV has some unique properties in terms of shape , size and  hemodynamics . We are getting more insights from  modern blood pool imaging by MRI , about  how the RV handles the blood volume .

I stumbled upon this excellent work  by Alexandru G. Fredriksson published in APS (American physiology society ) This MRI  study have  documented RV fucntion in a dramatic fashion.

We know RV has a unique shape  triangular ( partially  pyramidal ) . It can be inferred the RV cavity is formed by fusion of  many  eccentric spacial planes. We have always believed  RV handles the blood it receives from right atrium in a unique way .Now we are beginning to understand it .It is now documented the RV segregates the blood it receives into 4 components.

 

right ventricle physiology anatomy hemodynamics

It is curious  to know  RV inflow is connected to the outflow by an invisible   physiologic Bridge . About 44% of  blood traverse the RV in this fashion.

 

RVOT blood flow right ventricle

Note : RV blood flow preferentially enters the RVOT with out transiting RV body and apex.Image courtesy http://ajpheart.physiology.org/

 

Which is the most important part in RV ? (Among Inflow, Body, Apex, Out flow)

After reading this article it seems to me , the mechanical  function of RVOT could be most  vital. If it fails to handle the first increment  which  comes directly from  RV inflow, stasis  is likely in RV body and apex , elevating RVEDP and later promoting stasis leading to clinical events.

Clinical implication of this study

  • Differential dilatation RV chambers to pressure or volume  overload is observed .
  • We need to analyse why RV dilates in some   but   goes for hypertrophy in others when confronted with pressure overload (VPS vs PAH)
  • RV apical clot in restrictive cardiomyopathy  is a direct consequence of stasis  of blood  in RV apical zone .
  • RVOT pacing  may have a hemodynamic advantage  over RV apical pacing  . However , for anatomical reasons RV apical pacing  is  far safer than RVOT pacing where the lead  is subjected to constant life long strain due to this busy RV inflow to outflow express  high way !

Final message

Traditionally we have labeled  RV  as a  passive venous chamber .It is clearly a misnomer.It  has to handle both the venous and pumping function beat to beat with precision  without  back log .Obviously ,  RV has to think and work  more than it’s  big brother !

Reference

I wonder , if  there is  any other site other than APS . . . to  find crucial  answers in cardiac physiology  !

 

Right ventricle physiology blood flow 3d 4d analysisAfter thought

  • There is huge gap between physiologists  who work in research labs and the physicians at bed side .
  • I appeal all young cardiologists  to visit  APS  once in a while ,between your busy cath lab schedule and help narrow this gap.
  • Without understanding the physiology properly how are we going to intervene the pathology ?

 

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What are the patterns of RV enlargement in various clinical entities ?

Posted in cardiology congenital heart disese, Clinical cardiology, myocardial disease, Right ventricle, tagged , , , , , , , , , , , , on September 30, 2013| Leave a Comment »

Right ventricle is a passive venous component of the heart .It simply acts a  transit pump for blood to reach the lungs.

It  is true  , RV is dispensable in many complex congenital heart disease as we  can connect the great veins directly into the pulmonary artery  by  Fontan , Glean and it’s clones  bye passing this chamber . Still , by no means the importance of this chamber is to be underestimated.  RV dysfunction and failure  is the key to survival  many  disorders.RV shock is is cause of sudden cardiac death in acute pulmonary embolism and RV infarction .

RV is an unique muscular chamber .It is more of a triangular shape. It has  three different parts connected by three different angle .There is no true  apex  for RV , it is   connected  to Inflow and outflow in peculiar fashion .

In the  following table I have  tired to  describe  of how different parts of RV  behave in various disorders.

what is the morphology of RV enlargement RV inflow outflow body sinus portion of RV

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Does the right ventricle really dilate in ventricular septal defect ?

Posted in Uncategorized, tagged , , , , , , , on October 20, 2010| 1 Comment »

The following  questions  are asked frequently  in clinical cardiology classes on congenital heart disease.

What are the chambers that dilate in ASD ?

Right atrium and  right ventricle .

What are the chambers that dilate in VSD ?

LA, LV , ± RV,

* Image courtesy Wikipedia

While there is no controversy about ASD, The chambers that enlarge in VSD ,   is  by and large  poorly (or rather wrongly ) understood .  Whenever we  diagnose  VSD , our brain is tuned  to think  this way : Blood  will be  shunted form LV to RV.  RV  would  handle more blood and it  should   enlarge . In reality it does not happen.

The VSD  shunts  the  blood from  LV to RV outflow*   or even directly into  pulmonary artery  .  Hence , VSD even if it is large  , does not dilate  the RV until the onset of  pulmonary hypertension and RV dysfunction sets in . It is surprising to note , even the RVOT ( The entry point of most VSD jets) does not significantly  enlarge

Importance of diastolic shunting in determining RV size in VSD

It is also important to recognise, the VSD shunt predominately occur in systole .(90% ?) In systole , the RV is also contracting along with LV  , so it’s size is diminutive  and hence RV can not be volume overloaded in  most of the VSDs however large it may be. Instead in ASD , there is diastolic overloading   involving  all regions(Inflow, Body, Outflow) of  RV   .This enlarges the RV   in a classical  fashion.

Significance of  anatomical location of VSD and RV enlargement

When VSD shunts blo0d into RA as in Gerbode defect it is bound to enlarge RV (like ASD) as there is diastolic volume over load of RV.

In some large muscular VSD , RV body can be  volume  overloaded. This is because the VSD and RVOT are well separated geographically .The  blood that is coming in from LV can enter the pulmonary artery , only in the next cardiac cycle  . So , RV needs to accommodate the shunted  blood till the next beat. Hence RV enlarges.

What are the situations RV can enlarge significantly in VSD ?

  • Rare VSDs of inflow or large muscular VSDs.
  • Eisenmenger syndrome.
  • Tricuspid regurgitation
  • Pulmonary regurgitation
  • Associated RSOV.

Final message

Right ventricle   does not enlarge  significantly in uncomplicated  VSD .This is in contrary to the  traditional teaching and understanding  for  many years. It enlarges only in specific sub types of VSD  or  after the onset of PAH and cardiac failure .

Coming soon

Katz-Wachtel phenomenon is not  due to  bi -ventricular hypertrophy !

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Why we look lead V1 to diagnose RVH but look at V4R , to diagnose RV infarction ?

Posted in Cardiology - Clinical, tagged , , , , , , , , on July 2, 2009| 1 Comment »

The right ventricle  is a unique  chamber of the heart . It is the anterior most chamber and  triangular in shape.  Even though  the walls of RV are  not  clearly demarcated ,   it does  have  anterior ,  posterior, and lateral free surfaces   . Anatomically it has a inflow  body, apex and outflow portions . The apex of right ventricle , blends with the lower IVS at an acute angle.

How does RVH occur anatomically ?

The anatomy of RV is such that  it does not allow  it  a concentric  RVH ( like LVH ) . In fact , there is a  disproportionate free wall , anterior  wall   hypertrophy  many  situations  like  PHT/Pulmonary stenosis. The  infero posterior aspect of RV rarely show hypertrophy.

Since RV is the anterior most chamber, located just beneath the left border of sternum   RVH brings the RV  further closer to chest wall .This makes the V1 lead to show  tall R in V1.

What happens in RVMI ?

Unfortunately, when we  refer to RVMI , we generally do not make any efforts to locate or estimate it’s  size.  Since RV has , anterior , lateral and posterior surface  , the site  and  the  extent of the  mI will have a major impact  on the  ECG  features .

Most often  the RVMI occur as a  part of infero posterior MI  .Hence ,  it is uncommon for the anterior surface of RV to get involved.  But ,  it can be involved if  RCA gives of a   large RV branch  that reach the anterior surface of RV.

Anterior RVMI can occur as a part  of LAD MI  , if a large conal branch cross the RV surface.

What prevents the lead V1 from showing the  ST elevation of RVMI ?

  • Most of the RVMI do not involve the anterior surface of the RV so , less chances for ST elevation
  • Further , if a true posterior wall  MI  occur as a part of  RVMI (Which is often the case !)  V1 can never  show ST elevation  as the  posterior MI  tend to have a ST depressing effect in the V1, V2 leads.
  • Extensive IWMI , can have reciprocal ST depression in V1-V2.This again , prevents V1 lead to show the ST elevation

So many times , even though V1 lead is just sitting over the chamber RV it fails  to  pick  the  ST elevation forces of RVMI

Advantage of V4 R ?

V4R records remote RV forces , as these  signals are not contaminated by the inferio posterior ST forces. Hence  a  1mm ST elevation in right sided chest leads have good sensitivity  and specificity to diagnose RVMI .

When can V1 show ST elevation in RVMI ?

If the RV anterior wall is predominantly involved (Ie Anterior RVMI ) ST elevation can occur in V 1 like a anteroseptal MI.

rvmi ecg

Rarely a q RBB can occur in V1 in isolated RVMI.

Final message

V1 lead , though anatomically proximal to RV has less value in diagnosing RVMI since this lead picks up  Infero posterior  negative ST forces  and  the anterior  forces of RVMI get neutralised . So relying on lead V1 to diagnose RVMI is not adviced , except when  the anterior surface of RV is predominatly  involved.

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What is the difference between left ventricular pressure curve and right ventricular pressure curve ?

Posted in Hemodynamics, Tutorial in clinical cardiology, tagged , , , , , , , , , , on September 18, 2008| 2 Comments »

The pressure tracing between two chambers of the heart are distinctly different .

 Apart from the magnitude of the  pressure ,(LV at systemic pressure ) The morphology also changes.

  •  RV pressure curve is triangular in shape,
  •  Upstroke is not rapid , (Low dp/dt)
  •  There is no sustained peak ,
  •  There is an early fall and
  •  The pressure falls to zero which  never happens in LV.

Contary to this LV pressure curve is bullet shaped,  with a rapid upstroke, sustained peak, fall later, and does not touch zero.

RV/LV pressure curves in normal persons .Adapted from , Curtiss 1975 Circulation

Note : The shapes of RV curve will change in pathological states.Example in TOF, large VSD there will be left ventricularisation of RV pressure wave forms. Also  in pulmonary hypertension RV pressure may mimic a LV curve.

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