[HSF] Low gradient AS

Sun Dec 30 16:22:18 EST 2007

Bob, 
A thoughtful answer as usual. (Does that make me a suck up? I think it is just the season that has me thanking everyone.)

Actually I don't think that so many of these elderly women have dilated ventricles. I don't see them that much. Perhaps they just have stiff but not fixed valves that respond poorly to increased flow (they move a little) and sometimes have a coronary lesion or two that may contribute to the symptoms. Their post op CI are almost always less than or around 2.0 as they get off the aggressive periop fluid, SVR, etc management. I prefer to pull the Swan if they have one to let them readjust their own homeostasis rather than chase the numbers in circles pharmacologically for a couple of days. I am a nihilist or at least minimalist post op as well as intraop. Is not one of the purposes of surgery to minimize the need for medical support? Most seem to end up about the same (better or not) in a couple of months with or without treating every abnormality as not a potential disaster that we can watch but a disaster in evolution.  ??(not a typo)??
 An aortoplasty enlarging both the annulus and the whole oblique aortotomy with a tilt of the valve on the patch and one of the smaller (less bulky) frame can accomplish what you say. Your warning of not trading a small gradient for another makes good sense.

tea

----- Original Message ----
From: "rwmfglycar at aol.com" <rwmfglycar at aol.com>
To: OpenHeart-L at lists.hsforum.com
Sent: Sunday, December 30, 2007 3:50:16 PM
Subject: Re: [HSF] Low gradient AS

Michael,

It is likely that this patient has a dilated heart with?reduced systolic function. We saw these from the early days of aortic?valve replacement?in our Bronx population. The approach was very simple. What is her current cardiac output? What would be her cardiac output at an index of 2.5 to 3.0 L/min/m2? Let's say that the number is 4.2 L/min. Next question: what size valve of what model will give a gradient close to zero at that cardiac output? We had an idea of this because from the 60's we had been studying all valves in pulse duplicators and had a routine of measuring in the OR, post bypass, simultaneous ventricular and aortic pressures? and dye dilution cardiac outputs. 
??? Most of the valves when we started doing this were mechanical. In the 70's the first bioprostheses came in. The standard insertion technique was intra-annular. We knew what we called the mounting size of each design with its designated size. We could get an idea of the annular size from an ascending aorta angiogram. We would know in advance then if?an?available device would have the desired hemodynamic result of a very low transvalvar gradient. (We actually also had what we called the Performance Index which related the area of the device at the level of the annulus to the calculated effective orifice area). But in our minds what counted was how much pressure the ventricle would need to generate to produce a "normal"?cardiac output . 
??? In your example let us say that? to achieve this we would need a size 21 of brand X. We fear however that even a size 19 will be a tight fit and that the mean gradient will be 20mm Hg at a "normal" resting cardiac output. What help would that give to this failing sick ventricle? Answer simple: nothing. Putting in a 19 will not help the patient shorterm or long term. 
??? That left us two choices using a homograft or at least a size 21. In the Bronx with a lousy coroner system homografts were virtually unobtainable in the time we are talking about. For us the option was root enlargement.The circumferences of 19, 21 and 23 annuli are 60, 66 and 72 mm. A patch will easily produce a 6 mm enlargement of a 19 annulus. It is difficult to produce a 12 mm increase in circumference. It is easy to go from 19 to 21 but hard to go from 19 to 23.?But if 19 was not good enough the only basis for offering surgery was aortic root enlargement.?
We had good success with this approach. While cleaning out my basement recently I came across records of mean gradients at normal resting outputs achieved in a series of these patients. They varied between 5 and 15.
?? The other critical fact shown by many surgeons was that low ejection fractions due to aortic stenosis virtually always improved post replacement with a hemodynamically adequate device.
Go for it Michael. Just make sure to give the ventricle optimal myocardial protection.
?? Note that in Padua pulse duplicator studies of modern devices have been done. Unfortunately engineers love to describe the results in terms of energy losses etc. All the ventricle knows is how hard it has to push. Concentrate on mean gradients at normal cardiac indices.
?Bob.

Treat the patient, not the numbers, Michael.
;)
tea

----- Original Message ----
From: Michael Firstenberg <msfirst at gmail.com>
To: OpenHeart-L at lists.hsforum.com
Sent: Sunday, December 30, 2007 12:10:29 PM
Subject: [HSF] Low gradient AS

Not to curse myself, but we are seeing more and more "little old ladies"
with CHF, low EFs, low gradients (relative term), and severe AS (like areas
0.5).  While these are known to be higher risk, has anyone turned anyone
down - and if so what are the true contraindications (besides the usual
failure of the eyeball test).  My take is anything you put in has to be
better than what they have and if you do nothing, then they are toast.

A patient I am working up has a AVA of 0.4 with a peak of 42mmHg and a mean
of 24 mmHg with known CAD (moderate LAD disease from a cath in 2001!).   I
know we can get dobut stress echos and MRI, etc etc and ring up big bills,
but she has already been admitted 3 times with severe CHF problems in the
past 2 months and has an ankle fracture which no one will touch due to her
heart.  I get the sense that if we dont offer something they she may not
make it to the end of the year (yikes - that is in 2 days).

-michael
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