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Archive for the ‘Aortic valve replacement’ Category

It was the final case on weekend Echocardiogram review day, I asked my fellow for a brief summary of the patient. 

A 5 -minute conversation

“Yes, sir, he is a 62-year-old male retired govt officer. He has a severely stenosed aortic valve, with a peak gradient of 90 mmHg and a mean gradient that comes to almost 50 mmHg. LV  EF is 58%, GLS is 18, LVH is obvious. LA is not dilated (Didn’t measure volume though), but DT is short. Valve orifice is hovering around 1cm, mild calcium noted in LCC  I am not sure whether it’s bi or tricuspid still. The annulus is 22mm. The mitral valve is perfect, no calcium spill over to the mitral curtain and the rest of the annulus”.

“That is ok, what for he has come”?

“A GP from Tambaram has referred him after he detected a murmur over the chest”.

“Oh Ok. What are his symptoms”?

“He is denying any symptoms”.  

“Are you sure? did you ask him specifically about it during exertion”? 

“Yes, he says he can climb 3 flights of stairs. (In fact, he was sort of amused when I told him to be frank in his expression,since  he has a potentially serious obstruction in the main valve that connects his heart and body.”

“I agree, but his reaction was not inappropriate I thought, after all, he didn’t feel any symptoms right”. “So what shall we do for him?  TAVR? SAVR? or Leave him alone? Shall we put him on the treadmill? to document symptoms? Is it that risky”? 

“But , he says he can walk for a mile or two every day” 

“That’s fine. Can you really predict when his ventricle will fail and he may land up in a semi-emergency surgery?

“I think we can’t,  but why is he is so asymptomatic sir”?

“Wow, that’s more than a million-dollar question. You need to address that query to the vascular Goddess. I don’t know the answer.It is all about the ability of the heart to perfectly balance the ventricle and aorta in spite of severe obstruction. It is something like TIMI 3 flow and good FFR  in a patient with 90% occlusion.) My guess is, the LV does this by modulation of systemic pressure &  resistance in such a way , it neither feels the strain nor does it reduce the stroke volume much. By the way,  have you heard about this ? Z- Va score. I would like you to read about that. It will help you understand the hemodynamic nuances of severe AS and how the ventricle manages to serially couple the afterload of the vascular system”. 

“Make a pardon sir, I haven’t heard about it. What is Zva? 

“Never mind. It is not a new index. Was first introduced 16-years ago by Martin Briand et al from Quebec, heart Institute Canada  J Am Coll Cardiol 2005 Jul 19;46(2):291-8.  Z Va score(Valvulo-Arterial) is the collective flow impedance of the aortic valve and the entire aorta. It is more attractively defined as the cost of blood pressure in mmHg for pushing one ml of blood per body square meter area

Formula for Z va : (Systolic BP × Mean gradient)/ Stroke volume Index

Unit : mmhg /ml/m²

Normal value:  < 3.5 to 4.5 (Actually no normality, rather it must be acceptable value .It is still being defined )  if the cost is more than 5mmhg it suggests significant Aortic stenosis) A high value > 4.5 is a definite index of poor outcome. In a well-compensated heart, Zva is maintained far less than 5 and many such patients are asymptomatic as well. Zva has specific clinical value in all critical AS especially so if they are asymptomatic. It is no longer a research topic, has an important role in the bedside too. Here is an excellent resource on Z Va score from ESC.

 

Final message 

The timing of AVR in aortic stenosis is very critical. All symptomatic severe AS must be immediately intervened. Currently, with surgical risk falling rapidly ( & the option of TAVR looming large) even many of the asymptomatic AS need to be considered for valve intervention at the earliest before or at the onset of LV dysfunction. Zva’s score will definitely add more light to our  limited hemodynamic wisdom in aortic stenosis(Zeineb Hachicha  JACC 2019) 

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With TAVR (Transcutaneous aortic valve replacement ) threatening to take away the Aortic valve surgery atleast in high risk subsets from surgical domain ,a new development is taking place in aortic valve surgery. Minimally Invasive aortic valve replacement and implantation of low profile , bio prosthetic valve placed in aortic root without active suturing .This type of AVR  can be done without traditional  sternotomy  with minimal bypass time , less surgical morbidity and mortality.

It has some specific advantages over TAVR, as the native valve is removed , calcium is debrided and hence less stroke and para-valvular leak .In TAVR cardiologists are blinded ,do lot of guess work to place the valve in right position ,  struggle to handle the deformed and distorted native valve tissue .My belief is,surgery does a more precision job , since the valve is placed in  optimal position .One more issue is, complication of complete heart block and subsequent requirement of pacemaker , its prohibitively high for TAVR as on 2016.(up to 25% )

These new generation valve  are expected to  narrow the gap between AVR and  TAVR. Still. avoiding a surgery is the biggest advantage which drags most patients to TAVR. However, one should ensure quality shouldn’t be compromised for simplicity.

There are two valves available for suture less AVR  , both from Bovine pericardium.

1.Perceval (Psorin)

2.Intuity (Edwards)

p_20160415_174424_1.jpg

Evidence

CAVALIER and TRITON  (PERSIST -AVR forthcoming)

Message for the  patients

TAVR is a revolutionary  treatment modality, agreed .However , one need not blindly accept the  TAVR if offered especially in low and medium risk* situations just because it avoids a surgery.(*Of-course technology may evolve further ) Discuss with surgeons .Be well informed about all the intricacies.Currently  surgical risks seem to  overstated and TAVR risks are underplayed in spite of huge cost advantage in favor of surgical AVR.

A note of caution , for suture less AVR must be made .Basically , surgeons  tried to imitate the cardiologists, .Ironically , it has the same issues of TAVR for possible migration of valve.Conventional AVR  with active permanent fixation sutures will remain the 24 carrot gold standard for AVR and all others may  just glitter !

Please realise, medical decision making and consent forms are increasingly looking  similar to signing a  house mortgage loan which comes with  lots of known and unknown “conditions apply”!

Reference

tavr tavi avr surture less future of avr metaanalysis phan

 

 

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