Thyroid and Cardiovascular Problems ( Dr. Roy Christian, SpJ

8/20/2019 Thyroid and Cardiovascular Problems ( Dr. Roy Christian, SpJ

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Thyroid and CardiovascularProblem s

Roy Christian


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The cardiovascular signs and symptomsof thyroid disease are some of the mostprofound and clinically relevant ndingsthat accompany both hyperthyroidism

and hypothyroidism Both hyperthyroidism and hypothyroidism

produce changes in cardiac contractility,myocardial oxygen consumption, cardiacoutput, blood pressure, and systemicvascular resistance (SVR


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!lthough it is "ell #no"n thathyperthyroidism can produce atrialbrillation, it is less "ell recogni$edthat hypothyroidism can predispose toventricular dysrhythmias%

&n almost all cases these

cardiovascular changes are reversible"hen the underlying thyroid disorderis recogni$ed and treated


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Thyroid disease is 'uite common%

Current estimates suggest that it

aects as many as )* to +* of theadult female population and asmaller percentage of adult males%


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Cellular M echanism s ofThyroid H orm one Action

T- and T. are synthesi$ed by the thyroidgland in response to TS/%

The thyroid gland primarily secretes T-

(0*, "hich is converted to T. by 1monodeiodination in the liver, #idney, ands#eletal muscle%

The heart relies mainly on serum T.

because no signicant myocyte intracellulardeiodinase activity ta#es place, and itappears that T., and not T-, is transportedinto the myocyte


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BRAUNW ALD’S HARTD!SAS


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Ef fects of Thyroid H orm oneon CardiovascularH em odynam ics Thyroid hormone eects on the heart

and peripheral vasculature

include decreased SVR and increasedresting heart rate, left ventricularcontractility, and blood volume

Thyroid hormone causes decreased

resistance in peripheral arteriolesthrough a direct eect on VS2 anddecreased mean arterial pressure


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!ctivates the renin1angiotensin1aldosterone system and increasesrenal sodium absorption%

T. also increases erythropoietinsynthesis, "hich leads to an increasein red cell mass

Promote an increase in bloodvolume and preload%

Ef fects of Thyroid H orm oneon CardiovascularH em odynam ics


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Braun"ald’s hear# disease


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3iastolic function, as measured by the isovolumic relaxationtime, varies over the entire range of thyroid disease, includingovert hypothyroidism (4/, subclinical hypothyroidism (SC/,control (C, hyperthyroidism (/, hyperthyroidism after beta1

adrenergic bloc#ade (/ 5 6, and hyperthyroidism aftertreatment to restore normal thyroid function (7


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H yperthyroidism

6atients "ith hyperthyroidismpresent "ith characteristic signs andsymptoms, many related to the heartand cardiovascular system%

/yperthyroidism8 increasedformation and release of thyroid

hormones from the thyroid gland Thyrotoxicosis8 the clinical syndrome

that results from thyroid hormone

excess


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Cardiovascular Signs and Symptoms ofHyperthyroidism

6alpitations

!nginal chest pain

7xercise intolerance

!trial brillation

7xertional dyspnea

Cardiac hypertrophy

Systolic hypertension 6eripheral edema

/yperdynamic precordium

Congestive heart failure


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ATR!AL $!BR!LLAT!%N

The most common rhythm disturbancein patients "ith hyperthyroidism is sinustachycardia, but its clinical impact is

overshado"ed by patients "ith atrialbrillation resulting from thyrotoxicosis

Treatment of atrial brillation in the

setting of hyperthyroidism includesbeta1adrenergic bloc#ade to control theventricular response


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!nticoagulation of patients "ithhyperthyroidism and atrial brillationis controversial%

The ris# of systemic or cerebralemboli$ation must be "eighedagainst the potential for bleeding

and other complications of thistherapy


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H eart Failure

6atients "ith hyperthyroidism may havesigns and symptoms indicative of heartfailure

6atients "ith both severe and chronic

hyperthyroidism, exaggerated sinustachycardia or atrial brillation can producerate1related left ventricular dysfunction andheart failure

6reexistent ischemic or hypertensive heartdisease may also predispose thehyperthyroid patient to the development ofheart failure


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H ypothyroidism

The most common cardiovascularsigns and symptoms ofhypothyroidism are diametricallyopposed to those described forhyperthyroidism and may includebradycardia, mild hypertension

(diastolic, narro"ed pulse pressure,cold intolerance, and fatigue


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Cardiovascular Risks

Associated W ithH ypothyroidism &mpaired cardiac contractility anddiastolic function

&ncreased systemic vascularresistance 3ecreased endothelial1derived relaxation

factor

&ncreased serum cholesterol &ncreased C1reactive protein

&ncreased homocysteine


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The treatment of hypothyroidism in thesetting of #no"n or suspected cardiacdisease poses some challenges% &n

young,other"ise healthy patients "ithovert hypothyroidism, treatment "ith a fullreplacement dose of 91thyroxine (9evoxyl,Synthroid of +%: g;#g per d can be initiated

&n older patients, the adage of start lo" (


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M yxedem a Com a

The most severe form of hypothyroidismis that associated "ith profound C>Sdepression

and is called myxedema coma

the term only refers to patients in comaascribed to hypothyroidism

!ny of the signs and symptoms ofhypothyroidism may be present inmyxedema coma, but signi cantdepression of the sensorium is re'uired


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!ny of the signs and symptoms ofhypothyroidism may be present in myxedemacoma, but signi cant depression of thesensorium is re'uired

2yxedema coma is treated "ith thyroid hormone

replacement% 9oading dose of .== g of thyroxine&V, follo"ed by daily doses of = to +== g &V%

/ydrocortisone, .== mg;d &V in divided doses, isadministered empirically for possible coexisting

adrenal insu? ciency% !s an alternative to givinghydrocortisone, a single dose of dexamethasonemay be administered "hile the rapid cosyntropinstimulation test is performed% 4nce the test iscompleted, hydrocortisone is initiated%


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Thyroid and Cardiovascular Problems ( Dr. Roy Christian, SpJ