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Archive for the ‘prosthetic valve dysfunction’ Category

 

A 40 year old  women came  with acute dyspnea who had a prosthetic mitral valve implanted 2 years ago for RHD  .

An emergency  echo showed  a peak gradient of 35mmhg across the valve .She was on warfarin regularly and her last INR was 2.2.Heart rate  was 138/minute, lungs showed congestion .LA,LV were dilated. LV function appeared mildly compromised  but could not be accurately quantified as the  patient  was in distress.

 

The fellow on duty had no hesitation  in diagnosing prosthetic valve thrombus .He Initiated Inj streptokinse bolus followed by infusion  along with diuretics . After few hours the gradient regressed .Patient felt better .Every one was happy . The consultant congratulated the fellow for  the good job done .To recognize prosthetic valve obstruction early and  successfully lysing it too !  The fellow  felt gratified .

prosthetic valve obstruction thrombus 002

Since I  was hanging around the CCU , watching the proceedings , I Initiated  a debate which was  curious to the team that handled the  patient !

Was it really thrombotic obstruction that caused his symptoms ?

  • No one has visualized the thrombus
  • TEE was not done
  • Fluroscopic evaluation of disk motion was not performed
  • There was no documentation of raising FDP that would Indicate clot lysis.

All  we have  is an unexplained  tachycardia with raised  trans prosthetic gradient . . .

Why we are tuned to think  raised gradients  to be  synonymous with thrombus ?

There has  been lot of assumption here . Subsequent analysis of history and  clinical presentation revealed the patient had a febrile illness which triggered an  atrial tachycardia  that possibly  resulted in transient  LV dilatation and dysfunction.

Once the failure is controlled the gradient has come down , I argued !

Of course, this again could be  a guess work , How can you  still rule out a thrombus ? They wondered !

I told them ,  question here is not ruling in or ruling out prosthetic valve thrombus.

It is an important  lesson to learn , raised  prosthetic gradient is not equal to thrombus  in many  acute hemodynamic situations* .

Many factors other than prosthetic valve obstruction  can elevate the gradient.

After all ,  prosthetic valve orifice is inherently stenosed  .(MVO is  never >2.5sqcm in any prosthetic mitral valve) . So at times of tachycardia the gradient is bound to be elevated .

Other factors that can elevate trans – mitral gradient includes

  • LV dysfunction
  • Acute diastolic dysfunction
  • Acute peri-valvular MR
  • Loss of LA compliance

 *One of the  commonest (yet not recognised) cause for elevation of trans mitral prosthetic gradient is acute left ventricular failure due to any cause.It  can be either acute diastolic dysfunction or a sudden raise in  blood pressure that result in  after load mismatch.

Final message

Please remember flow across prosthetic valve is governed by  delicate  local hemodynamic rules .The gradient  is  critically dependent on heart rate, LA  size and compliance , LVEDP and after-load mismatch if any !

Transient raise can occur at times of tachycardia and falling LV function (Mitral valve has to push hard, in the process elevating the gradient)

Simple raise in trans-valvular gradient should be carefully interpreted. Since visualising thrombus in routine TTE is  difficult  in an acutely  dyspnic  patient  many of us have taken this  granted !

Nothing wrong in playing  guess games in medicine . . . but we  need to acknowledge it!

*Note:Other causes for chronically elevated gradients like pannus formation, mechanical defects of valve, degenerated prosthesis  should be addressed separately.

 

 

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