Hypothyroidism and heart failure

[Guest guest]

Gee whiz, maybe I better get that thyroid level checked after all, and take my meds if I need them!

May 28, 2005

http://thyroid.about.com/b/a/173244.htm?nl=1

Researchers Discover Thyroid, Heart Failure ConnectionNot only is low thyroid function -- hypothyroidism -- very common in congestive heart failure, it also indicates a reduced likelihood of recovery, and an increased chance of death. But based on earlier work showing that whatever leads to heart failure it is always preceded by changes in the heart cells, a new study demonstrates that a moderate dose of thyroid hormones (TH) over 30 days actually "normalizes" the shape of the cardiac cells (myocytes) and reduces stress on the heart's wall nearly 40%. "As patients move toward heart failure, the myocytes become longer and flatter, and the wall stress worsens," according to the head of the laboratory where the research was performed. "But moderate TH therapy selectively targeted myocyte cross-sectional shape and modified it in a positive way. This is the first clue on what might be a novel therapeutic approach to heart failure because of the return to a more normal heart cell shape," according to A. Gerdes, director of the Cardiovascular Research Institute, University of South Dakota. The study, entitled "Thyroid hormones induce unique and potentially beneficial changes in cardiac myocyte shape in hypertensive rats near heart failure," appears in the May issue of the American Journal of Physiology-Heart and Circulatory Physiology, published by the American Physiological Society. More Animal Testing Needed Before Move to Humans Based on positive preliminary findings, the University of South Dakota-Florida A & M University research paper reports that moderate TH positively affected heart remodeling and reduced wall stress in ways warranting further study. However the authors warn that since the mechanism of thyroid hormone influence on diseased hearts isn't known, continuous TH therapy could endanger heart failure patients, particularly in accidental overdose. In the U.S. alone, heart failure contributes to or causes about 300,000 deaths each year, according to the National Heart, Lung, and Blood Institute. The unit of the National Institutes of Health estimates that about 5 million people in the U. S. have heart failure and the number is growing. Each year, 550,000 people are diagnosed for the first time. Unique Cardiac Cell Re-Shaping Reduced Heart Wall Stress 38% "This is the first study to look at the implications of thyroid hormone therapy on hypertensive heart failure," Gerdes said. There is "an abundance of evidence that thyroid dysfunction contributes to heart failure," Gerdes noted, "but this study showed that a moderate TH dosage reduced wall stress 38% without affecting blood pressure." The paper said the effect came about because the TH "produced a unique, never-before-observed pattern of myocyte remodeling." This is particularly important, Gerdes said, because no matter what the underlying cause of heart failure in humans, the last phase in heart failure – progression to dilatation – is always accompanied by elongation of heart muscle cells (myocytes), without concomitant cell widening. The paper notes that "it isn't clear at this time whether the critical defect in myocyte remodeling in progression to congestive heart failure is due solely to excessive myocyte lengthening or to impaired transverse growth. It is possible that myocytes are responding normally to increased preload by adding new series sarcomeres, whereas the normal check on this system -- balanced myocyte transverse growth -- is where the true dysfunction lies." However Gerdes warned since "this is the first study to disclose these positive effects with TH, we don't yet have enough information to do this intelligently in humans. Care should be taken in administering TH to humans for heart disease since there is so little information available from animal studies." The current study said that the "most interesting effects were on the left ventricular myocyte shape…and these changes correlated beautifully with echocardiogram-derived measurements of chamber diameter and wall thickness. Additionally, the anatomical changes led to a surprising reduction in left ventricular systolic wall stress despite the presence of sustained hypertension." Next steps

Since there appears to be such a strong link between low thyroid function and heart failure, more animal studies need to focus on this entire subject. "There is a strong likelihood that improvements in human patient outcome may occur if we have the proper scientific basis on which to proceed in an intelligent manner," Gerdes said. Future animal studies also should try to demonstrate that TH treatment can actually reduce mortality in heart failure, since this is the most important question from a clinical standpoint, Gerdes said. An area where additional work is merited, the paper says, is to uncover the signaling mechanisms by which the THs alter myocyte shape, which aren't known. If the impaired thickening of myocytes in progression to chamber dilatation and failure is related to thyroid dysfunction, which is common in heart failure patients, it is possible that treatment may help arrest progressive chamber dilatation. Interestingly, there was no change in myocyte shape with the low-dose TH despite reversal of the myosin-isoform abnormality, which is a marker of fetal-gene program (FGP) reactivation, the paper notes. "This suggests that signaling related to myocyte growth could be independent of changes in the FGP" -- another potential area for follow up. Source: "Thyroid hormones induce unique and potentially beneficial changes in cardiac myocyte shape in hypertensive rats near heart failure" May 2005 issue of the American Journal of Physiology-Heart and Circulatory Physiology, published by the American Physiological Society. FOR MORE INFORMATION Various articles on the thyroid/heart disease connection are featured here at the Thyroid site at About.com.

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[Guest guest]

Patty

My father in law suffered from graves disease (hyperthyroidism) and

had his thyroid irradiated many years ago. As a result, it moved

back into a normal range for several years but ultimately his

thyroid failed completely which most will do eventually if they are

partially irradiated and definitely if they are irradiated

completely. Long story short, neither he or nor his doctor picked

up on the thryoid failure (even though I hounded them about it

because he seemed so tired to me). About seven years ago he was

diagnosed with congestive heart failure due to extremely low thyroid

and he died 2 years ago. It could have been prevented! The low

thryoid did exactly what that article described! Thanks for

sharing that article. My husband has had borderline thyroid values

before and now he doesn't but he sure acts more tired and finds it

hard to lose weight. He also had first degree heart block. He did

a stress test but they said he is fine. He has had 2 ekg's that

showed bradycardia which is too slow a heart rate. I was thinking

about going to see a doctor like julie did because his thyroid tests

are inthe normal range so they say there is nothing to worry about.

Well I don't want what happened to my fatherinlaw to happen to

dale. I sure wish the thyroid was better understood so we can get

the help we need. There are probably millions of people with less

than optimal thyroid function that don't know it because it isn't

easy to diagnose.

Hugs

kathy

> Gee whiz, maybe I better get that thyroid level checked after all,

and take my meds if I need them!May 28, 2005

> http://thyroid.about.com/b/a/173244.htm?nl=1

>

> Researchers Discover Thyroid, Heart Failure Connection

> Not only is low thyroid function -- hypothyroidism -- very common

in congestive heart failure, it also indicates a reduced likelihood

of recovery, and an increased chance of death. But based on earlier

work showing that whatever leads to heart failure it is always

preceded by changes in the heart cells, a new study demonstrates

that a moderate dose of thyroid hormones (TH) over 30 days

actually " normalizes " the shape of the cardiac cells (myocytes) and

reduces stress on the heart's wall nearly 40%.

> " As patients move toward heart failure, the myocytes become longer

and flatter, and the wall stress worsens, " according to the head of

the laboratory where the research was performed. " But moderate TH

therapy selectively targeted myocyte cross-sectional shape and

modified it in a positive way.

> This is the first clue on what might be a novel therapeutic

approach to heart failure because of the return to a more normal

heart cell shape, " according to A. Gerdes, director of the

Cardiovascular Research Institute, University of South Dakota.

> The study, entitled " Thyroid hormones induce unique and

potentially beneficial changes in cardiac myocyte shape in

hypertensive rats near heart failure, " appears in the May issue of

the American Journal of Physiology-Heart and Circulatory Physiology,

published by the American Physiological Society.

> More Animal Testing Needed Before Move to Humans

> Based on positive preliminary findings, the University of South

Dakota-Florida A & M University research paper reports that moderate

TH positively affected heart remodeling and reduced wall stress in

ways warranting further study. However the authors warn that since

the mechanism of thyroid hormone influence on diseased hearts isn't

known, continuous TH therapy could endanger heart failure patients,

particularly in accidental overdose.

> In the U.S. alone, heart failure contributes to or causes about

300,000 deaths each year, according to the National Heart, Lung, and

Blood Institute. The unit of the National Institutes of Health

estimates that about 5 million people in the U. S. have heart

failure and the number is growing. Each year, 550,000 people are

diagnosed for the first time.

> Unique Cardiac Cell Re-Shaping Reduced Heart Wall Stress 38%

> " This is the first study to look at the implications of thyroid

hormone therapy on hypertensive heart failure, " Gerdes said. There

is " an abundance of evidence that thyroid dysfunction contributes to

heart failure, " Gerdes noted, " but this study showed that a moderate

TH dosage reduced wall stress 38% without affecting blood pressure. "

> The paper said the effect came about because the TH " produced a

unique, never-before-observed pattern of myocyte remodeling. " This

is particularly important, Gerdes said, because no matter what the

underlying cause of heart failure in humans, the last phase in heart

failure – progression to dilatation – is always accompanied by

elongation of heart muscle cells (myocytes), without concomitant

cell widening.

> The paper notes that " it isn't clear at this time whether the

critical defect in myocyte remodeling in progression to congestive

heart failure is due solely to excessive myocyte lengthening or to

impaired transverse growth. It is possible that myocytes are

responding normally to increased preload by adding new series

sarcomeres, whereas the normal check on this system -- balanced

myocyte transverse growth -- is where the true dysfunction lies. "

> However Gerdes warned since " this is the first study to disclose

these positive effects with TH, we don't yet have enough information

to do this intelligently in humans. Care should be taken in

administering TH to humans for heart disease since there is so

little information available from animal studies. "

> The current study said that the " most interesting effects were on

the left ventricular myocyte shape…and these changes correlated

beautifully with echocardiogram-derived measurements of chamber

diameter and wall thickness. Additionally, the anatomical changes

led to a surprising reduction in left ventricular systolic wall

stress despite the presence of sustained hypertension. "

> Next steps

> Since there appears to be such a strong link between low

thyroid function and heart failure, more animal studies need to

focus on this entire subject. " There is a strong likelihood that

improvements in human patient outcome may occur if we have the

proper scientific basis on which to proceed in an intelligent

manner, " Gerdes said.

> Future animal studies also should try to demonstrate that TH

treatment can actually reduce mortality in heart failure, since this

is the most important question from a clinical standpoint, Gerdes

said.

> An area where additional work is merited, the paper says, is to

uncover the signaling mechanisms by which the THs alter myocyte

shape, which aren't known. If the impaired thickening of myocytes in

progression to chamber dilatation and failure is related to thyroid

dysfunction, which is common in heart failure patients, it is

possible that treatment may help arrest progressive chamber

dilatation.

> Interestingly, there was no change in myocyte shape with the

low-dose TH despite reversal of the myosin-isoform abnormality,

which is a marker of fetal-gene program (FGP) reactivation, the

paper notes. " This suggests that signaling related to myocyte growth

could be independent of changes in the FGP " -- another potential

area for follow up.

> Source: " Thyroid hormones induce unique and potentially beneficial

changes in cardiac myocyte shape in hypertensive rats near heart

failure " May 2005 issue of the American Journal of Physiology-Heart

and Circulatory Physiology, published by the American Physiological

Society.

> FOR MORE INFORMATION

> Various articles on the thyroid/heart disease connection are

featured here at the Thyroid site at About.com.

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