Overview of hypothyroidism
Heart disease due to hypothyroidism characterized by chills, dry skin, low perspiration, fatigue, unresponsiveness, and edema of the lower extremities, mostly caused by primary hypothyroidism, secondary or central hypothyroidism, and thyroid hormone resistance syndrome, usually treated with thyroid hormone replacement therapy.
Definition
Hypothyroid heart disease is the lack of thyroxine in the body or the biological effects, causing interstitial hypermucinous edema, diffuse small focal degeneration and fibrosis of the myocardium, which leads to abnormalities in the size, function and conduction of the heart and other manifestations, and clinically, there will be hypothyroid coronary artery disease, hypothyroidism cardiomyopathy, pericardial effusion, cardiac arrhythmia, blood pressure abnormalities, and cardiac insufficiency and other manifestations [1].
Hypothyroidism is referred to as hypothyroidism, so hypothyroidism behavioral heart disease is also known as hypothyroid heart.
It manifests as symptoms such as cold fear, dry skin, low sweat, fatigue, unresponsiveness and lower limb edema [2-3].
Morbidity
There is no accurate epidemiological data on hypothyroid heart disease, but the prevalence of hypothyroidism increases gradually with age, and the annual incidence of clinical line hypothyroidism is 3.5:1000 in adult females and 0.6:1000 in males, and 70%~80% of hypothyroidism is accompanied by cardiovascular lesions [4].
Causes
Causes
Primary hypothyroidism: hypothyroidism caused by the thyroid itself, accounting for more than 95%, mainly including autoimmune, thyroid surgery and I131 treatment.
Secondary or central hypothyroidism: due to hypothalamus and pituitary pathology caused by thyrotropin-releasing hormone (TRH) or thyroid-stimulating hormone (TSH) production and secretion decrease. Such as pituitary tumor, pituitary surgery and external irradiation, pharyngotrophic tumor, pituitary ischemic necrosis.
Thyroid hormone resistance syndrome: Hypothyroidism caused by unresponsiveness of peripheral tissues to thyroid hormones [1].
Pathogenesis
Thyroid hormone is secreted by the thyroid gland, and thyroid hormone is necessary to maintain normal metabolism and promote growth and development.
Thyroid hormones affect lipid metabolism. Thyroid hormones elevate cholesterol by promoting hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase activity, and promote the conversion of cholesterol to bile acids in the liver, and the latter action is stronger than the former, with the overall effect being a lowering of cholesterol.
In hypothyroidism, the rate of blood cholesterol decomposition and metabolism is reduced, causing cholesterol and triglyceride levels to rise and inducing the development of atherosclerosis.
When the organism is in hypothyroidism conditions, Na+-K+-ATPase and mucopolysaccharide removal from the heart and other tissue cells are inhibited, causing intracellular sodium retention, swelling, necrosis and rupture, promoting myocardial remodeling, and causing apoptosis of cardiomyocytes, which induces cardiac hypoplasia.
When hypothyroidism occurs, capillary permeability increases and lymphatic return is impeded, causing plasma proteins to rush to the pericardial cavity in large quantities, resulting in pericardial effusion.
In addition, thyroid hormones have a significant effect on the normal physiological function of the heart, which can increase the heart rate, myocardial contractility, cardiac output and myocardial oxygen consumption. When there is insufficient thyroid hormone production due to various reasons, the related functions are diminished.
Symptoms
Main Symptoms
In adults, hypothyroidism often develops insidiously and progresses slowly, and the typical symptoms of hypothyroid heart disease often do not appear until months or even years later.
General symptoms
Fear of cold, dry skin, little sweat, coarse and thick, sparse and dry hair, fatigue, speechlessness, lethargy, memory loss, slow reaction time, body temperature lower than normal, hoarse voice, weight gain, and in a few cases, anemia.
Cardiovascular system manifestations
Initial manifestations include palpitations, slow heart rate, and easy fatigue.
When cardiac insufficiency and pericardial effusion appear, manifestations of cardiac insufficiency appear, such as dyspnea during activity, and in severe cases, sit-up breathing (unable to lie down due to dyspnea and forced to sit up).
Patients with elevated blood lipids and a long history of the disease may have coronary atherosclerosis, angina attacks, or even acute myocardial infarction attacks.
Other symptoms
Special Facial Features
Patients will have mucous edema, which is mainly manifested as indifferent expression, dull gaze, pale and waxy face, rough and thickened skin of edematous eyelids, sparse eyebrows, and in a few patients, thick and brittle fingernails with many cracks, hoarse voice, and so on.
Digestive system manifestations
Loss of appetite, abdominal distension, constipation, etc.
Muscle and joint system manifestations
Muscle weakness, muscle tension, stiffness and myalgia are common, and in severe cases, they may be accompanied by joint pain and immobility.
Psychoneurological manifestations
Depression, mental abnormality, and coma in severe cases [4].
Medical treatment
Department of Medicine
Cardiovascular medicine
When palpitations, chest tightness, shortness of breath, shortness of breath, dyspnea, coma and other symptoms occur, prompt medical attention should be sought.
Preparation for medical treatment
Preparation for medical consultation: registration, preparation of documents, and common problems.
Tips for the doctor
Wear loose-fitting clothes for the examination.
Preparation Checklist
Symptom list
Pay particular attention to the time of onset of symptoms, special manifestations, etc.
Are there any symptoms such as fear of cold, weight gain, fatigue, memory loss, etc.?
Any palpitations, chest tightness, swelling, etc.? When did they occur?
List of medical history
Any history of hypothyroidism or thyroid surgery or 131 iodine treatment?
Any similar symptoms in the past?
Checklist
Test results from the last 6 months, which can be brought with you to the doctor’s office
Imaging tests: thyroid ultrasound, X-ray, echocardiogram, etc.
Laboratory tests: thyroid hormone test, thyroid antibody test
List of medications
Medication used in the last 3 months, if available, bring the box or package with you to the doctor’s office.
Levothyroxine, Digoxin, Simvastatin, Lovastatin, Fenofibrate, etc.
Diagnosis
Diagnosis based on
Medical history
Patients may have a history of primary hypothyroidism, secondary or central hypothyroidism, and thyroid hormone resistance syndrome [1].
Clinical manifestations
General symptoms
Fear of cold, dry, scanty, coarse and thick skin, sparse and dry hair, fatigue, scanty speech, lethargy, memory loss, unresponsiveness, lower than normal body temperature, hoarseness, weight gain, and in a few cases, anemia.
Cardiovascular system manifestations
Palpitation, chest tightness, fatigue, dyspnea on activity, and in severe cases, sit-up breathing (unable to lie down due to dyspnea and forced to sit up), cardiac arrhythmia, angina pectoris, and so on.
Laboratory Tests
Blood tests
Look for problems such as anemia and infection.
A decrease in the number of red blood cells, lower hemoglobin, and low maturity of red blood cells can help in the diagnosis of anemia. If elevated neutrophils are found, there may be signs of infection.
Thyroid Antibody Test
This mainly includes testing for thyroid peroxidase antibodies (TPOAb) and thyroglobulin antibodies (TgAb) to help clarify the cause of hypothyroidism and guide treatment.
If patients with autoimmune thyroiditis are positive for serum TGAb, TPOAb and TBAB, the positive rate of TGAb and TPOAb is 50% to 90%, and the positive rate of TBAb is 20% to 30%, it helps to diagnose hypothyroidism.
Thyroid hormone test
The main indicators include serum thyroid stimulating hormone (TSH), total thyroxine (TT) and free thyroxine (FT).
In hypothyroidism, TT4 is often <3µg/dl earlier than the decrease of TT3, TT3 measurement has little diagnostic value for hypothyroidism, about 30% of clinical hypothyroidism patients have normal TT3, and only in the late stage and the seriously ill, the decrease of TT3 is <100µg/dl.
Precautions during the examination: routine blood test is required before the examination.
Imaging examination
X-ray examination
Purpose of examination: To check the changes of heart through X-ray.
Significance: Chest X-ray shows generalized enlargement of the heart shadow and sluggishness and small amplitude of the heart beat under fluoroscopy.
Precautions during examination: X-ray examination requires some braking, and younger children may have movement artifacts due to cooperation problems. During X-ray examination, parents should control the examination area of the child to prevent blurring of the image caused by the child’s movement, thus affecting the diagnosis.
Echocardiography
Echocardiography can visualize the changes in the chambers of the heart, the movement of the ventricular walls, and the size of the ejection fraction.
In hypothyroid heart disease, pericardial effusion, decreased diastolic and systolic function of the left ventricle, and asymmetric septal hypertrophy can be seen.
Precautions during the examination: There is no significant discomfort during transthoracic cardiac ultrasound, but there may be a feeling of pressure in the chest due to the pressurization of the probe.
Thyroid ultrasound
Ultrasound of the thyroid gland is used to identify the cause of hypothyroidism.
It may reveal a decrease in blood flow to the thyroid gland.
If there is any jewelry around the neck, especially in women, it is important to remove the jewelry and to fully expose the neck so that it can be scanned without any special treatment.
Differential Diagnosis
Coronary artery disease
Similarities: palpitations, chest tightness, easy fatigue, exertional dyspnea may occur
Differences: Coronary artery disease in clinical manifestations are all in the activity, exertion, emotional excitement when the heart. The anterior region of the sternum behind the pressure-like pain, accompanied by a burning sensation, accompanied by the back of the shoulder radiating pain, rest for three to five minutes will be able to relieve, oral nitroglycerin most of the two minutes or so will be able to relieve.
Dilated cardiomyopathy
Similarities: chest tightness, shortness of breath, accompanied by paroxysmal dyspnea at night.
Differences: Dilated cardiomyopathy is characterized by enlargement of the cardiac border and edema of the face and limbs.
Non-specific pericarditis
Similarities: palpitations, shortness of breath.
Difference: non-specific pericarditis is characterized by distant heart sounds, bilaterally enlarged borders, and pericardial effusion on cardiac ultrasound.
Treatment
Aim of treatment: reduce hypothyroidism, alleviate the effect of hypothyroidism on the heart, alleviate and try to eliminate the symptoms of heart disease.
Treatment principle: In addition to the necessity of thyroxine replacement therapy, comprehensive treatment to lower cholesterol, relieve angina and improve cardiac function should be carried out.
Medication
Thyroxine supplementation
Commonly used drugs: levothyroxine.
Used to treat hypothyroidism.
The dose of treatment depends on the condition, age, weight and individual differences, the goal is to restore normal levels of thyroid hormones, improve myocardial metabolic disorders, so that the heart disease becomes in order to recover, permanent hypothyroidism patients need lifelong replacement therapy [1].
Improvement of cardiac function and reduction of pericardial effusion
Commonly used drugs: furosemide, spironolactone, sacubitril valsartan and so on.
Drug effects: reduce cardiac load, reverse ventricular remodeling, improve cardiac function.
Precautions for the use of drugs: those with excessive amount of pericardial effusion, which affects hemodynamics, need urgent pericardiocentesis to extract fluid. When the disease is critical, small doses of digitalis preparations can be added to the application of thyroxine replacement therapy, which needs to be used with caution in small quantities [5-8.
Lipid lowering
Commonly used drugs: simvastatin, lovastatin, fenofibrate and so on.
Effects: Reduce the level of low-density lipoprotein, prevent the occurrence of atherosclerosis, and relieve angina pectoris.
Precautions for use: Regular review of liver and kidney function is required when using drugs.
Other treatments
For hypothyroidism caused by pituitary tumor, timely targeted treatment of pituitary tumor, such as surgery, radiofrequency destruction and other treatments, may help to alleviate hypothyroidism.
For hypothyroidism caused by excessive iodine intake, thyroid function can be adjusted by reducing iodine intake.
For hypothyroidism caused by the use of antithyroid agents, prompt reduction or discontinuation of the medication may help to restore the function of the thyroid gland.
Prognosis
Cure
Clinical symptoms of hypothyroidism can be significantly improved after effective treatment, and the improvement of heart disease symptoms is particularly obvious. After 1 month of treatment, the heart may shrink significantly and the electrocardiogram may return to normal within 4 to 6 weeks.
Hazards
Hypothyroidism can cause palpitations, chest tightness, shortness of breath, wheezing and other symptoms, affecting the patient’s daily work and life. In addition to cardiac lesions, hypothyroidism may also lead to the following problems.
Untreated hypothyroidism in infancy can lead to stunted growth and irreversible serious damage to IQ. Untreated hypothyroidism in early childhood can cause irreversible damage to the physical and intellectual abilities of the child.
In adult women, severe hypothyroidism can be accompanied by decreased libido and ovulation disorders, menstrual cycle disorders and increased menstrual flow, and infertility.
In men, hypothyroidism can lead to loss of libido, impotence and reduced spermatozoa, which may affect fertility to a certain extent.
Untreated hypothyroidism may also be complicated by mucous edema, coma, shock, etc., and may even be life-threatening.
Untreated hypothyroidism during pregnancy has adverse effects on both the mother and the fetus, including spontaneous abortion, preterm delivery, pre-eclampsia, gestational hypertension, postpartum hemorrhage, low birth weight babies, stillbirth, and impaired fetal intellectual and motor functions.
Daily
Daily management
Follow the doctor’s prescription of full dosage and course of medication, and do not stop the medication or change the dosage privately to avoid disease progression.
Avoid consuming large amounts of goiter-causing foods, such as cabbage, kale and cassava, for a long period of time.
Patients with hypothyroidism caused by iodine deficiency should eat foods and vegetables containing more iodine, such as selecting the right amount of kelp, seaweed, available iodized salt, iodized soy sauce, iodized eggs and bread iodized. When frying vegetables, it should be noted that iodized salt should not be put into boiling oil, so as not to volatilize iodine and reduce the concentration of iodine.
When acute heart failure attack, should promptly take a semi-sitting position, keep calm, deep breathing, family members to assist as soon as possible to get in touch with the hospital.
Quit smoking and drinking, smoking and long-term alcohol consumption may have a great impact on the function of the thyroid gland, which is not conducive to the condition of hypothyroidism [3].
Disease monitoring
After treatment, you can observe whether symptoms such as dyspnea, telangiectasia, and edema are relieved. If they are not relieved, the patient can be followed up in time.
Follow-up review
Follow-up to monitor whether the thyroid hormone supplementation is appropriate to avoid underdosing or overdosing.
After starting treatment, follow-up visits are usually every 4 to 8 weeks. After the thyroid function is stabilized, follow-up examination can be done every 6~12 months.
Follow-up examinations include thyroid hormone function tests, thyroid ultrasound, echocardiography and other tests to monitor the condition.
Prevention
Patients without thyroid autoimmune disease should continue to consume iodized salt, and pregnant and breastfeeding women, in particular, should be supplied with adequate iodide.
Patients with thyroid autoimmune disease should avoid eating large quantities of high iodine foods such as kelp and seaweed for a long period of time, and use iodized drugs reasonably under the guidance of doctors.
When applying antithyroid medication to adult hyperthyroidism, the medication must be used strictly according to the doctor’s prescription, paying attention to the dose and course of treatment, and adjusted according to the condition at any time [9-10].