Overview of Hyperthyroidism
A series of cardiac disorders caused by hyperthyroidism, including symptoms related to hyperthyroidism and cardiac symptoms such as arrhythmia and heart failure, are caused by the direct or indirect effects of high thyroid hormones on the cardiovascular system. The active treatment of hyperthyroidism is accompanied by the treatment of the corresponding cardiovascular abnormalities, such as antiarrhythmia, cardiotonicity, and diuresis.
Definition
Hyperthyroidism, excessive thyroid hormone on the heart directly and indirectly caused by heart enlargement, heart failure, arrhythmia and angina pectoris and a series of symptoms and signs of endocrine metabolic disorders of heart disease known as hyperthyroidism heart disease, referred to as hyperthyroidism heart.
Hyperthyroidism for heart disease is one of the most common complications of hyperthyroidism [1].
Incidence
The incidence of hyperthyroid heart has increased in recent years, accounting for 10% to 22% of the incidence of hyperthyroidism.
Atrial fibrillation occurs in about 70% of hyperthyroid hearts.
Etiology
Causes
The increase of thyroid hormone in the blood circulation during hyperthyroidism causes increased cardiac excitability and hypermetabolism.
Excess thyroid hormone enhances cardiac sensitivity to catecholamines, exerts positive inotropic effects, and pathological changes such as peripheral vasodilatation and compensatory increase in cardiac output occur, leading to the development of hyperthyroid heart disease [2].
Predisposing factors
Low potassium: it can lead to the reduction of myocardial stress, the body under the influence of hyperthyroidism is a high metabolic state caused by excessive contraction of the myocardium, coupled with the effect of low potassium on the cardiomyocytes, which leads to a series of cardiac arrhythmias and conduction block.
Infection: Infection is a predisposing factor for many diseases. Infection occurs in the high metabolic state of the body, which can further aggravate the cardiac load and induce heart failure.
High risk factors
Those with a family history of hyperthyroidism are susceptible to hyperthyroid heart.
People with potential ischemic heart disease are prone to hyperthyroidism.
People with hyperthyroidism and untimely treatment are prone to hyperthyroidism.
Pathogenesis
The pathogenesis of hyperthyroidism is not well understood. However, it may be related to the following factors.
Direct effects of thyroid hormones on the cardiovascular system
Increased heart rate
Higher production of cyclic adenosine monophosphate cAMP, which increases myocardial contractility.
Increased transcription of the Ca2+-ATPase gene, which increases uptake of calcium and glucose and increases myocardial contractility.
Congestive heart failure
Increased contraction of cardiomyocytes, high energy expenditure, heat production and heat dissipation, increased return and cardiac output with increased microcirculatory shunting, further aggravating cardiac burden.
Increased secretion of erythropoietin, resulting in an increase in the total number of red blood cells.
Arrhythmia
Increased synthesis of Na+-K+-ATPase, increased Na+, decreased K+ and accelerated metabolism in the myocardium, resulting in myocardial hypoxia and overconsumption of substances, affecting the regulation of cardiac rhythms such as cardiomyocyte refractory period and excitation threshold.
Enhanced action of adrenaline
Adrenaline has the effect of accelerating heart rate, enhancing myocardial contractility and accelerating conduction. Excessive enhancement results in cardiac overload, ectopic rhythms, cardiac hypertrophy, heart failure, and coronary artery spasm (angina pectoris, myocardial infarction).
Increased number of adrenergic receptors on cardiac myocytes.
Hepatic degradation of catecholamines is inhibited, resulting in decreased adrenaline degradation.
Activation of the renin-angiotensin-aldosterone system (RAAS)
The central nervous system is stimulated with sympathetic arousal.
Aldosterone secretion increases, causing sodium retention and increasing blood volume.
Peripheral vascular resistance increases, increasing cardiac afterload.
Cardiac positive inotropy, positive frequency increases, and load increases.
Proliferation of cardiomyocytes and vascular smooth muscle cells, resulting in cardiac hypertrophy [3].
Symptoms
Main Symptoms.
Symptoms of hyperthyroid heart include symptoms of hyperthyroidism and symptoms of heart disease; atypical individuals may have only symptoms of heart disease, especially in the elderly.
Symptoms of hyperthyroidism
Hypermetabolic symptoms, which may be characterized by fatigue, excessive sweating, fear of heat, and weight loss.
There may be protruding eyes, photophobia, diplopia, and tearing.
Nervous system may manifest as insomnia, irritability, nervousness, anxiety, inattention, irritability, and so on.
Other symptoms such as palpitations, shortness of breath, hyperphagia, active bowel sounds, anemia, edema under the tibialis anterior, menstrual disorders in females, and gynecomastia.
Cardiac symptoms
Arrhythmia is mainly characterized by atrial fibrillation, atrial flutter, ventricular tachycardia, atrial tachycardia, etc.; it may be manifested as panic, flushing, and fainting in severe cases.
When heart failure occurs, it can be manifested as shortness of breath, sedentary respiration, lower limb edema.
Myocardial ischemia can be manifested as palpitations, chest pain, etc. [4].
Consultation
Department of Medicine
Cardiovascular medicine
When symptoms of arrhythmia, angina pectoris, or heart failure such as palpitations, chest pain, and shortness of breath occur, it is recommended that prompt medical attention be sought.
Endocrinology
When symptoms of hyperthyroidism worsen, such as excessive eating, excessive sweating, significant weight loss, palpitations and hand tremors, it is recommended to consult a doctor.
Preparation
Consultation: Registration, Preparation of documents, Frequently asked questions
Tips for medical treatment
Do not eat or drink the night before your visit so that you can have an examination on an empty stomach.
Preparation Checklist
Symptom list
Pay particular attention to the time of onset of symptoms, special manifestations, etc.
Is there shortness of breath, palpitations, flushing?
Is there any nocturnal awakening, sedentary breathing, lower limb edema, chest pain?
Are there hand tremor, weakness, excessive sweating, photophobia, irritability, poor concentration?
Is there pyrexia, polyphagia, weight loss?
List of medical history
Is there a history of thyroid disease?
Is there a history of thyroid surgery or 131I treatment?
Is there a family history of thyroid disease?
Any history of atrial fibrillation or heart failure?
Checklist
Test results from the last six months, which you can bring with you to your doctor’s appointment
Laboratory tests: blood test, thyroid function, blood biochemistry, etc.
Imaging tests: electrocardiogram, cardiac ultrasound, thyroid ultrasound, thyroid nuclear imaging, thyroid iodine uptake rate.
Medication list
Medication used in the last 3 months, if available in boxes or packages, bring with you to the doctor’s office
Antithyroid medications: e.g. methimazole, propylthiouracil.
Diuretics: e.g. furosemide, spironolactone.
Medications that affect thyroid function: e.g., amiodarone, iodine-containing contrast agents
Diagnosis
Diagnosis is based on
Medical history
History of atrial fibrillation of unknown cause, poorly treated with digitalis drugs.
History of heart failure, but poorly treated.
History of thyroid disease.
History of use of medications that affect thyroid function, such as amiodarone and iodine-containing contrast media.
A family history of autoimmune thyroid disease.
Clinical manifestations
There are manifestations of hyperthyroidism hypermetabolism such as fatigue, excessive sweating, thermophobia, warm skin, hypothermia, humidity, and weight loss.
There are hyperthyroid ocular signs such as proptosis, photophobia, diplopia, and tearing of the eyes.
There are goiter signs such as nodular or diffuse enlargement of the thyroid gland.
There are hyperthyroidism manifestations such as frequent insomnia, irritability, nervousness, anxiety, inattention, and irritability.
Arrhythmia manifestations such as palpitations and arrhythmia, heart failure manifestations such as shortness of breath and sedentary breathing, and myocardial ischemia manifestations such as panic, pharyngeal constriction and chest pain.
There are hyperthyroidism manifestations such as hyper appetite, active bowel sounds, and frequent bowel movements.
Hyperthyroidism manifestations such as menstrual disorders in women and gynecomastia.
Laboratory tests
Thyroid function: to know the level of free triiodothyronine FT3, free thyroxine FT4, thyroid stimulating hormone TSH, etc.; the decrease of TSH and the increase of FT3 and FT4 suggest hyperthyroidism.
Cardiopulmonary four: including myoglobin, B-type natriuretic peptide, ultrasensitive troponin, creatine kinase isoenzyme MB quality, can understand the cardiac function; atrial B-type natriuretic peptide elevation suggests heart failure, the remaining three high suggests myocardial ischemia.
Blood routine: can know whether there is anemia, infection; no anemia and infection can suggest that heart failure is not caused by infection.
Dynamic blood pressure examination: to understand the fluctuation of blood pressure and pulse pressure difference; large fluctuation of blood pressure and large pulse pressure difference suggest hyperthyroidism.
Imaging examination
Cardiac ultrasound: to understand the structure of the four chambers of the heart, size and valves, ejection fraction, etc.; atrial enlargement, ventricular enlargement, valvular regurgitation, ejection fraction <50% are all suggestive of cardiac pathology.
Electrocardiogram (ECG): it can understand the heart rate, heart rhythm, and the relationship between ECG leads, etc. ST-T change, high T wave, abnormal P wave, Q-T interval prolongation, P-Q interval change, and atrial fibrillation, etc. suggest that the heart rhythm is abnormal.
Thyroid ultrasound: to understand the volume and morphology of the thyroid gland; diffuse or nodular enlargement suggests hyperthyroidism.
Thyroid iodine uptake rate: increased 131I uptake rate suggests hyperthyroidism.
Thyroid nuclear imaging: to understand the function of thyroid tissue; hot nodules suggest hyperthyroidism.
Chest X-ray: can understand the heart shape, size, etc.; prominent pulmonary artery arch, spherical shape, and heart shadow enlarged to both sides are suggestive of heart disease [5].
Differential diagnosis
Coronary heart disease
Similarity: palpitations, chest pain and other manifestations.
Differences: hyperthyroidism is ineffective after treatment with vasodilating drugs.
Rheumatic heart disease
Similarity: both may have heart murmur.
Differences: Hyperthyroidism has no apical tremor and poor response to digitalis.
Treatment
Treatment principle: once diagnosed, hyperthyroidism should be controlled as early as possible and effectively, which is the key to treatment; medication should be given first, and surgery is feasible when necessary.
Treatment goal: to eradicate hyperthyroidism and cure non-organic changes of hyperthyroidism.
General treatment
Dietary management
Low iodine diet: avoid foods containing too much iodine such as kelp, nori, seafood.
Ensure sufficient calories and nutrition, especially protein and B vitamins.
Avoid stimulating foods: e.g. strong tea, coffee, sports drinks, etc.
Pay attention to rest
Avoid overwork.
Sedative medication may be used in case of severe irritability or insomnia.
Emotional management
Avoid emotional excitement.
Medication
Anti-hyperthyroidism
Antithyroid drugs (ATD)
Indications are mild to moderate hyperthyroidism; mild to moderate enlargement of the thyroid gland; pregnant women; advanced age; those who are not suitable for surgical treatment; before surgery and 131I treatment; those with moderate to severe hyperthyroidism with protruding eyes; and those who have relapsed after surgery and are not suitable for 131I treatment.
Adverse reactions mainly include liver function impairment, leukopenia, skin rash.
Commonly used drugs include methimazole, propylthiouracil.
Normally, methimazole is preferred; propylthiouracil is preferred in severe cases, hyperthyroidism crisis, and pregnant patients.
Antiarrhythmic
β-blockers
Hyperthyroidism combined with atrial fibrillation and atrial fibrillation is not self-resolving after thyroid function is restored; hyperthyroidism heart failure with myocardial hypertrophy, left ventricular remodeling; elderly patients with a heart rate of >90 beats / minute
May have adverse reactions such as bradycardia, allergy, gastrointestinal reactions.
Commonly used drugs include metoprolol, propranolol, atenolol.
Correction of heart failure
Digitalis drugs
The indications are for people with heart failure combined with recovery of thyroid function.
Commonly used drugs include deacetylmorillonin (optional for those with rapid ventricular rate), toxic trichothecenes K (optional for those with irregular ventricular rate).
Diuretics
Indicated for those presenting with heart failure, especially during acute episodes and with significant fluid retention.
Adverse effects include the possibility of hypokalemia (furosemide), hyperuricemia (hydrochlorothiazide), and hyperkalemia (spironolactone).
Commonly used drugs include furosemide, hydrochlorothiazide, and spironolactone.
Angiotensin converting enzyme inhibitors/angiotensin receptor antagonists (ACEI/ARB)
Indications are hyperthyroid heart failure with cardiac hypertrophy and left ventricular remodeling, and hyperthyroid myocardial ischemia.
Adverse effects include angioedema, irritating dry cough, hyperkalemia, hypotension, and renal insufficiency.
Commonly used drugs include captopril and valsartan.
Aldosterone Receptor Antagonists
Indications are for those with NYHA cardiac function class II or higher and have been poorly controlled with other medications.
Adverse effects mainly include deterioration of renal function and hyperkalemia.
Commonly used drugs include spironolactone and eplerenone.
Beta-blockers
Indications are structural heart disease, NYHA cardiac function class II or above.
Adverse effects mainly include bradycardia, hypotension, fluid retention, and malaise.
Commonly used drugs include metoprolol and bisoprolol.
Sodium-glucose cotransporter protein 2 inhibitors
Indications are hyperthyroidism complicated by heart failure, type 2 diabetes mellitus.
Adverse reactions mainly include genitourinary tract infection, ketoacidosis.
Commonly used drugs include dagliflozin, engliflozin.
Anti-coronary therapy
Angiotensin-converting enzyme inhibitors/angiotensin receptor antagonists (ACEI/ARB)
Indications are hyperthyroid heart failure with cardiac hypertrophy and left ventricular remodeling, and hyperthyroid myocardial ischemia.
Adverse effects include angioedema, irritating dry cough, hyperkalemia, hypotension, and renal insufficiency.
Commonly used drugs include captopril and valsartan.
Nitrates
Indications are for those with hyperthyroid myocardial ischemia.
Adverse reactions mainly include headache, rapid heart rate, flushing, hypotension.
Commonly used drugs include isosorbide mononitrate, isosorbide dinitrate.
Calcium antagonists
Indications are for those with hyperthyroid myocardial ischemia.
Adverse reactions mainly include peripheral edema, palpitations, constipation, facial flushing.
Commonly used drugs include diltiazem, nifedipine [5-7].
131I治疗
Indications are thyroid enlargement of II degree or above; allergy to ATD; when thyroid function is controlled at mild to moderate level and cardiac function is basically recovered; with hematopoiesis; combined with hepatic and renal dysfunction; and contraindications to surgery.
Adverse reactions mainly include hypothyroidism [8].
Surgical treatment
Indications: when thyroid function returns to normal and cardiac function basically recovers; moderate-to-severe hyperthyroidism with ineffective medication; retrosternal goiter; those with suspected malignant tumors; mid-pregnancy (4-6 months); and ineffective ATD treatment.
Contraindications: those with severe cardiopulmonary, hepatic, and renal diseases; early and late pregnancy (1~3 months, 7~9 months).
The surgical procedure is subtotal thyroidectomy [5].
Prognosis
Cure
Untreated hyperthyroidism is not self-healing.
Most of those who are diagnosed and treated early and with good compliance have significant remission or cure.
Irreversible structural lesions of the heart cannot be cured.
Hazards
Poorly controlled hyperthyroidism and untreated hyperthyroidism can lead to serious heart disease such as arrhythmia and heart failure, which may progress to irreversible disease.
Untimely treatment can seriously affect daily life, work, and quality of life, and in severe cases can be life-threatening.
Daily
Daily Management
Dietary management
Low potassium diet: Avoid eating too much food with high potassium content such as seafood, nori, fungus, pickles, etc.; choose tofu, winter melon, zucchini, eggplant and other food with low potassium content.
Ensure sufficient calories; restrict water intake in heart failure.
Eat a balanced diet with more fruits and vegetables and high protein foods (e.g., dairy products, eggs, soy products) [9-10].
Life management
Stop smoking and drinking.
Regular work and rest, avoid overwork.
Disease monitoring
The use of drugs should be monitored on time for therapeutic effects and adverse drug reactions.
Monitor blood count and liver function regularly if using anti-thyroid drugs.
Follow-up examination
Review thyroid function every month and thyroid antibody every 3 months after ATD treatment.
Review thyroid function every 1~2 months after 131I treatment.
Review thyroid function every 6~8 weeks after surgical treatment.
Prevention
Smoking cessation and avoidance of iodine overdose can effectively prevent hyperthyroidism and hyperthyroidism heart.
People with hyperthyroidism and related risk factors (e.g. family history of hyperthyroidism, ischemic heart disease, untreated hyperthyroidism, etc.) should have their thyroid function and thyroid ultrasound checked regularly for early detection and treatment.