Feeds:
Posts
Comments

Posts Tagged ‘www.cardiommc.org’

Who killed Starr -Edwards valve ?

Posted in cardiac surgery, Cardiology - Clinical, cardiology -Therapeutics, tagged , , , , , , , , , , , , on January 15, 2011| 5 Comments »

Prosthetic valve implantation has revolutionized the management of  valvular heart disease . The original concept valve  was a ball in a cage valve  , still considered as a  fascinating discovery.  It was conceived by the young Dr Starr and made by Engineer Edwards  .This was followed   by long hours of arguments,  debates and  experiments that ran into many months . The  silent corridors of  Oregon hospital Portland USA remain the only witness  to their hard work and motivation.  At last,  it happened , the first human valve was implanted in the year 1960. Since then . . . for nearly  50 years these valves  have done a seminal  job for the mankind.

With the advent of  disc valve and bi-leaflet valve in the  later decades of 20th century , we had to say a reluctant good-bye to this valve.

There is a  lingering question among many of the current generation cardiologists and surgeons why this valve became extinct ?

Starr and Edwards with their child !

We in India , are witnessing these old warrior inside the heart functioning for more than 30 years.From my institute of Madras medical college  which probably has inserted more Starr Edwards valve than any other  during the 1970s and 80s by Prof . Sadasivan , Solomon victor , and Vasudevan and others .

It is still a mystery why this valve lost its popularity and ultimately died a premature death.The modern hemodynamic  men  working from a theoretical labs thought  this valve was  hemodynamically  inferior. These Inferior valves worked  like a  power horse  inside the hearts  the poor Indian laborers  for over 30 years.

A Starr Edwards valve rocking inside the heart in mitral position

The cage which gives  a radial support* mimic  sub valvular apparatus, which none of the other valves can provide.

* Mitral  apparatus has 5 major  components. Annulus, leaflets, chordae, pap muscle, LV free wall.None of the artificial valves has all these components.  Though , we would love to have all of them technically it is simply not possible.  The metal cage of Starr Edwards  valve partially satisfies this  , as  it acts as a virtual sub valvular apparatus.Even though the cage has no contact with LV free wall, the mechano hydrolic  transduction of  LV forces to the annulus  is possible .

Further , the good hemodyanmics of this valve indicate , the cage ensures co axial blood  flow  across the mitral inflow throughout diastole. .Unlike the bi-leaflet valve ,  where the direction of  blood flow is determined by the quantum of leaflet excursion  in every beat . In bileaflet valves  each leaflet has independent determinants of valve  motion . In Starr Edwards valve the ball is the leaflet . In contrast to bi-leaflet valve , the contact area  of the  ball and the blood in Starr Edwards  is a smooth affair  and  ball makes sure  the LV forces are equally transmitted to it’s surface .

The superiority of bi-leaflet valves and disc valves  (Over ball and cage ) were  never proven convincingly in a randomized fashion . The other factor which pulled down this valve’s popularity was the supposedly high profile nature of this valve. LVOT tend to get narrowed in few undersized hearts.  This  can not be an  excuse , as no consistent  efforts were made to miniaturize this valve which is  distinctly possible.

Sudden deaths from  Starr Edwards valve  .

  • Almost unheard in our population.
  • The major reason  for the long durability of this valve is due to the  lack of  any metallic moving points .
  • Absence of hinge  in this  valve  confers  a huge mechanical  advantage with  no stress points.
  • A globe / or a ball  has  the universal hemodynamic advantage. This shape makes it difficult for thrombotic focus to stick and grow.

Final message

Science is considered as sacred as our religion .  Patients believe in us. We believe in science. A  good  durable valve  was  dumped from this world  for no good reason. If commerce is the  the main issue ( as many still believe it to be ! )  history will never  forgive those people who were  behind the murder of this innocent device.

Cardiologists and Cardio thoracic surgeons are equally culpable  for the pre- mature exit of this valve from human domain.  Why didn’t they protest ?  We  can get some solace  ,  if  only we can impress upon  the current valve manufacturers  to  give a fresh lease of life to this valve .

http://www.heartlungcirc.org/article/S1443-9506%2810%2900076-4/abstract

Read Full Post »

Aborted and abandoned primary PCI !

Posted in Cardiology -Interventional -PCI, My presentations, Uncategorized, tagged , , , , , , , , , , , on December 8, 2010| Leave a Comment »

It is well  recognised for STEMI  to get aborted   spontaneously or through intervention.

Can a glamorous procedure like  Primary PCI be redundant ?

Yes of course . This paper,  is about how a planned  Primary PCI  can go awry  . . . Presented in the Annual scientific sessions of cardiological society of India Kolkatta December 2010.

Down load full presentation  in PDF format (primary_pci_)

Summary of the presentation

ABORTED  AND     ABANDONED    PRIMARY PCI

S.Venkatesan  G.Gnanavelu.R.Subramanian .Geetha Subramaninan

Madras Medical College. Chennai

Primary PCI has become the  standard of care  for acute STEMI in all  those eligible patients. Apart from the individual & institutional expertise ,the  key  to success  lies in  expediting   the symptom to balloon time to less than an hour.

Even though  STEMI   is characterized  by  acute total obstruction , it  is also a fact during this critical time window , a less recognised   positive  phenomenon takes place within the  ill fated coronary artery. Intrinsic fibrinolytic activity gets activiated and begins to take on the thrombus head on .It should be recalled this is the  earliest intervention in STEMI by natural forces , with zero time window . The power of this natural lytic process has  never  been easy to predict and quantiate . But  we  have  often realised  such a phenomenon do occur often and  is referred  by  various  terminologies like spontaneuous  thrombolyis, aboted MI etc .The exact incidence  is not estimated .In this era of  primary PCI we have found a new opportunity to confirm  this concept.

It has been  observed during  primary PCI ,  an occasional patient  may  have  either  a totally  patent IRA  or a minimal &  insignificant lesion  like luminal irregularity .This has  subsequently led on to cancellation of the procedure .We report our experience with  two patients with  this particular situation .One patient with IWMI with a time window   of  6hours had a totally patent  RCA.  Even , the luminal irregularities were difficult to locate .The other patient had anterior MI with ongoing ischemic pain.He was taken up for primary PCI.The initial angiogram  showed a total mid LAD  obstruction . As soon as the  guidewire reached the thrombotic lesion the  artery opened up   wth a TIMI  3 flow .There was no residual lesion or thrombus  noted. Both of the above  patients  were  young , smokers . 2b 3a antagonists were not administered. We infered, both had thrombotic STEMI and   presumed  to  had either spontaneous reperfusion , or  reperfusion assisted by dye injection & guidewire manipulation. They were  shifted out of cath lab with a new code of aborted primary PCI and  were discharged with normal LV function .It need  to be  realised here, a   distinction must me made between  aborted PCI  and   abandoned or failed  primary PCI  as  the later  connote a negative outcome. The  causes for abandoning  primary PCI are due to complex  lesions like bifurcation /Trifurcation lesions , triple vessel disease  with difficulty in identifying culprit lesions.A  Primary PCI is  considered failed  when the  IRA patency  is not accomplished or  failure to  sustain myocardial flow inspite of  IRA patency (No-Reflow) . These patients may end up in CABG or occasionally fall back on  thrombolysis  which was considered a inferior modality just few hours earlier !

.                                         We conclude , in the management of STEMI ,  primary PCI once contemplated need not always reach it’s  logical conclusion. There are situations  it can  get  aborted or abandoned  at various levels . Aborted  primary PCI  due to spontaneous  lysis though uncommon ,  can be a therapeutically and financially rewarding concept for the patient  and  physician .

Read Full Post »