Pathology of heart failure

2021-01-28 12:00 AM

Digital has little benefit, and can even be dangerous, with acute myocardial infarction, non-pacemaker bradycardia, and end-stage heart failure

Define

Heart failure is a medical condition in which the heart muscle loses the ability to supply blood according to the body's needs, at first during exertion and when at rest.

This concept holds true for the majority of cases, but has not explained the cases of heart failure with high cardiac output and even in the early stages of heart failure where cardiac output is normal.

Epidemiology

In Europe over 500 million people, the estimated heart failure frequency is between 0.4 and 2%, meaning that there are 2 million to 10 million people with heart failure. In the United States, the estimated number is 2 million people with heart failure, of which 400,000 are new each year. The general frequency is about 1-3% of the population in the world and over 5% if the age is over 75. In our country there are no exact statistics, but based on the population of 70 million people, there are 280,000-4,000,000,000. people with heart failure need treatment.

Reason

Heart failure

Arterial hypertension, simple or combined aortic valve stenosis, myocardial infarction, toxic myocarditis, infection, myocardial diseases, paroxysmal supraventricular tachycardia, seizure atrial, tachycardia, paroxysmal ventricular tachycardia, complete atrioventricular block, aortic stenosis, congenital heart, also ductus arteriosus, ventricular septal defect.

Right heart failure

Mitral stenosis is the most common cause, followed by chronic lung disease such as: bronchial asthma, chronic bronchitis, tuberculosis, bronchiectasis, acute pulmonary infarction. Scoliosis hunchback, thoracic malformation, congenital heart disease such as pulmonary artery stenosis, Fallot quadriplegic, atrial septal defect, late stage ventricular septal, infectious endocarditis, tricuspid valve damage, in addition some rare causes such as left atrial mucus. In the case of pericardial effusion and pericardial spasm, the clinical symptom resembles right-heart failure but is essentially diastolic failure.

Total heart failure

In addition to the two above causes leading to total heart failure, there are also the following causes: dilated cardiomyopathy, total heart failure due to hyperthyroidism, Vitamin B1 deficiency, severe anaemia.

Mechanism of pathogenesis

The hemodynamic function of the heart depends on four factors: pre-load, afterload, myocardial contractility and heart rate.

Pre-load: The elongation of the post-diastolic myocardial fibers, the anterior load depends on the amount of blood accrued to the ventricles and is represented by the volume and blood pressure in the diastolic ventricle.

After-load: After-load is the resistance that the heart encounters in the process of ejection contraction, leading to the peripheral resistance, the afterload increases, the speed of myocardial fibers decreases; therefore, the internal ejection volume decreases the systole.

Myocardial contractility: The force of contraction of the heart muscle increases the internal ejection volume of the systole, the force of the heart muscle is influenced by the sympathetic nerves in the myocardium and the amount of catecholamine circulating in the blood.

Heart rate: Increased heart rate increases cardiac output; heart rate is influenced by sympathetic nerves in the heart and the amount of Catecholamine circulating in the blood. Circulatory failure occurs when factors 1, 2 and 4 are disturbed, and heart failure occurs without factor 3.

In heart failure, the cardiac output decreases, the first phase will have a compensating effect:

The blood stasis of the ventricles causes the myocardial fibers to elongate, the ventricles relax, the force of ejection becomes stronger, but at the same time increases the end diastolic volume.

Ventricular thickening due to an increase in the diameter of cells, an increase in the number of mitochondria, an increase in the number of new muscle contraction units marks the onset of a decrease in the function of myocardial contractility. When compensatory mechanisms are exceeded, heart failure becomes decompensated and clinical symptoms appear.

Diagnose

Heart failure

Mechanical symptoms:

There are 2 main symptoms: Shortness of breath and cough. Shortness of breath is the most common symptom. At first, shortness of breath with exertion, later attacks, sometimes sudden difficulty breathing, sometimes increasing difficulty breathing; Cough occurs at night when the patient is exertion, dry cough, sometimes with bloody blood.

Physical symptoms:

Cardiac examination: The apex of the heart was deviated to the left, and a slight systolic murmur was heard at the apex due to the mitral regurgitation.

Lung examination: Hear moisture at 2 bases of lung. In the case of heart attack can hear a lot of hissing and snoring.

Blood pressure: Normal or decreased blood pressure, normal blood pressure.

Subclinical:

X-ray: Film straightening the heart is big, especially the heart chamber, left atrium is larger in the open 2 leaves, left ventricle dilates with enlarged and thickened lower left arc, the blurred lung is in the hilum.

Electrocardiogram: Increased diastolic or left ventricular systolic load. Left axis, left ventricular thickening.

Echocardiography: The size of the left ventricle is dilated; the ultrasound also shows the left ventricle function and the cause of heart failure such as aortic valve regurgitation ... etc.

Hemodynamic exploration: If you have cardiac ventilation, an angiogram accurately assesses the severity of some heart valve diseases.

Right heart failure

Mechanical symptoms:

Difficulty breathing more or less depending on the degree of heart failure, frequent difficulty breathing, but no exacerbations of shortness of breath such as heart failure heart failure. More or less cyanosis depending on the cause and severity of right heart failure.

Authentication mark:

Mainly peripheral blood stasis with enlarged liver, imprisonment, smooth face, pressure pressure, active treatment with smaller heart support and liver diuretic, after treatment of enlarged liver called "braised liver", if the liver has been stagnant for a long time. It is called "cirrhosis of the heart" with sharp, strong density. The cervical vein is floating, responds to the venous liver (+) in the position of 450. Central venous and peripheral venous pressure increase.

Oedema: Soft oedema initially in the lower limbs and later systemic oedema, possibly accompanied by ascites, pleural effusion. Less urine 200-300ml / 24 hours.

Cardiac examination: In addition to the signs of the cause of heart failure, we also hear tachycardia, sometimes right horseback, systolic blowing in the tricuspid valve due to a possible tricuspid regurgitation. Normal systolic blood pressure, increased diastolic pressure.

Subclinical:

X-ray: Except for the case of right heart failure due to pulmonary valve stenosis characterized by bright lung, other causes of right heart failure on blurred straight lung film, dilated pulmonary artery, heart snout up due to right ventricle stretch. On left tilt film lost light behind sternum.

ECG: Right axis, right ventricular thickening.

Echocardiography: dilated right ventricle, pulmonary hypertension.

Hemodynamic probe: Increases in RV end diastolic pressure, usually increased aortic pressure.

Total heart failure

Right-heart failure often predominates. Patients with frequent dyspnoea, systemic oedema, spontaneous neck veins, increased venous pressure, enlarged liver, often ascites, pleural effusion, decreased systolic blood pressure, increased diastolic blood pressure, X-ray of the whole heart, electrocardiogram can thicken both ventricles.

Heart failure rating

According to the New York Heart Association:

Grade 1: Patient has heart disease but has no physical symptoms. Physical activity is normal.

Grade 2: The muscle symptoms appear only when exertion is limited, physical activity is limited.

Grade 3: Muscle symptoms appear even with mild exertion, limiting physical activity.

Grade 4: Muscle symptoms appear frequently even when the patient is at rest.

Classification of chronic heart failure according to Tran Do Trinh

Grade 1 heart failure: Difficulty breathing during exertion, coughing up blood, no swelling, not enlarged liver.

Heart failure degree 2: Shortness of breath when walking at medium speed. When walking, stop to breathe, mild oedema, liver is not big or big, 2cm below ribs. Feedback venous liver (+) in position 450.

Heart failure grade 3: Difficulty breathing worse or decrease, total oedema, liver> 3cm below the ribs, soft, feedback of the venous liver (+) in position 450, liver treatment completely shrinks.

Heart failure degree 4: Frequent shortness of breath, patients have to sit up to breathe, liver> 3cm below the ribs, solid density, sharp edges, treatment not responding or shrinking.

Treatment of heart failure

Digitalis

Originally used to treat heart failure, it is still widely used today. It has the following properties:

Increases the force of heart muscle contraction.

Slow heart rate.

Reduces conduction in the heart.

Increased ventricular stimulation.

Point:

Digital is clearly indicated in stasis heart failure with atrial fibrillation. However, if it is sinus rhythm, its role is still debated. Its other indication is in supraventricular arrhythmias such as atrial fibrillation, atrial flutter, and paroxysmal Bouveret-type paroxysmal supraventricular tachycardia.

Contraindications:

Absolutely when there is digital poisoning. Other contraindications:

Grade 2 and 3 atrioventricular blocs without a pacemaker.

Severe irritable ventricular state.

Congested cardiomyopathy.

Lack of oxygen.

Lower blood potassium.

Digital is less beneficial and can even be dangerous: acute myocardial infarction (except if there is a rapid atrial fibrillation), non-pacemaker bradycardia, end-stage heart failure, chronic heart failure, spasmodic pericarditis, heart failure with high cardiac output, heart diseases due to metabolic overload such as haemoglobin infection, powder infection.

Drug interactions:

The following drugs can increase digoxin levels: erythromycin, tetracycline, quinidine, amiodarone, verapamine.

In the treatment of chronic heart failure, there are two commonly used types: digoxin and digitoxin, but because digoxin has fast acting and fast elimination, it has a fast treatment effect while it is difficult to cause poisoning, so it is preferred. Note that digoxin is excreted by the kidneys and digitoxin is excreted by the liver. Therefore, if renal failure, digitoxin should be used while liver failure should use digoxin. In pregnant women digitoxin crosses the placental barrier while digoxin does not. In fact, there is no one regimen that is completely right for every patient. Treatment dose depends on the patient's sensitivity to the drug according to the principle that the elderly or heart failure with very large dilated heart, thin patients must reduce the dose of the drug. In general, the usual dose for attack treatment is digoxin 0.25mg (2 times / day for a week then return to the maintenance dose of 1/2 to 1 tablet / day, drink every day or even can drink every day without rest depending on the object. For digitoxin, it is compulsory to take a break such as taking 3 days off for 3 days due to its long half-life. Treatment area of ​​the drug: blood digoxin 1- 2.5ng / ml, blood digitoxin 15-35 ng / ml. However, for children with effective zone around 3 (1ng / ml, when treating, poisoning symptoms must be monitored for timely treatment attitude.

Rest and eating regimen

The patient's mode of activity depends on the degree of heart failure. When you have severe heart failure, you must rest completely at the hospital bed. Eating less than 2 grams of salt / day is necessary if heart failure level I and II, less than 0.5 grams / day if heart failure grade II, IV.

Diuretic

Still considered mainstream in the treatment of stagnant heart failure. With mild heart failure, the moderate dose thiazide diuretic is also sufficient to respond well to the combination with a pale diet. It is not necessary to give loop diuretics early unless there is no response to thiazide. Thiazide dose of 25mg (1-4 tablets / day, Trofurit 40 mg (2-3 tablets / day. These two types are salt-eliminating diuretics), so it is necessary to give each batch of potassium salt (1-2g / day) Severe stagnation may be combined in waves with a distal tubular potassium-sparing diuretic (Spironolactone) because there is often secondary aldosterone hyperaemia.

Vasodilators

Nitrate derivatives: widely used to reduce respiratory symptoms (shortness of breath) of heart failure. The starting dose is then small and then increased slowly to avoid side effects such as headache. The therapeutic dose for Isosorbide dinitrate is about 120mg / day. Similarly, can use mononitrate, paste trinitrine, molsidomine.

Arterial relaxants Helps to improve low supply. Hydralazine effective but disadvantages must use high doses difficult to implement (12-16 divided tablets 4). Prazosin works well, but weakens quite quickly afterward. In general, these drugs are rarely used today.

ACE inhibitors

The prognosis of patients with heart failure has been markedly improved. It not only improves symptoms, but also improves prognosis. Principles of use must be followed to avoid possible drug-induced complications, especially in patients receiving diuretics. The starting dose was small (6.25mg / day with Catopril) then increased to 50 - 150mg / day depending on the case.

Beta inhibitors

Previously seen as contraindicated. However, it has recently officially introduced the treatment of heart failure. The following drugs have been widely accepted: metoprolol, bisoprolol and especially Carvedilol. Use of this drug as a rule is that once heart failure has stabilized (not in acute heart failure), the small dose is gradually increased. With Carvedilol 12.5mg starting dose 1 / 4-1 / 2 tablets / day.

Phosphodiesterase inhibitors (Amrinone, Milrinone, Enoximone)

The mechanism of action is to increase the amount of AMPc, which has two effects: dilating the arteries and increasing myocardial contractility that does not depend on the receptors (. and dobutamine is ineffective.

Treat according to the type of heart failure

Acute heart failure

Board. Management measures for acute heart failure.

1. General measures

Sedation with morphine

2. Adjust the ease factors

Arrhythmia, anaemia, increased blood pressure

3. Adjust the lack of oxygen

Oxygen, supportive respiration if needed.

4. Specific treatment

Drugs: diuretics, vasodilation, myocardial spasm, aortic balloon, surgery: valve replacement, congenital perforation.

Board. Drugs used in the treatment of acute left heart failure.

Medicine

Mechanism

Physiological effects

Effective treatment

Diuretic:

* Furosemide 40-80mg IV

 

Diuretic

 

Reduce your burden

 

Against pulmonary oedema

Vasodilation:

*Morphine 5-10mg TM, TB, TDD.

* Trinitrin: 10-150 (g / min intravenous infusion or nitrate derivatives, oral.

*Nitroprusside: 25-150(g/minute)

 

Varicose veins

Varicose veins

 

 

Dilated arterioles and veins

 

Reduce your burden

Reduce your burden

 

 

Reduce the burden and after-load

 

Against pulmonary oedema

Against pulmonary oedema

 

 


Against pulmonary oedema and increase cardiac output

Increased myocardial contractility:

* Dobutamine: 250-750 (g / min

* Dopamine: 100-600 (g / min

* Digital (lanatoside C, digoxin) 1 intravenous tube

 


Sympathy

 


Sympathy

Preparing Na-K ATPase pump

 


Increased heart contractility

 


Increased cardiac contractility, decreased afterload (low dose), increased afterload (high dose).

Increased heart contractions, reduced pre-load and afterload.

 


Increased cardiac flow

 


Increased cardiac flow, increased blood pressure (high dose).

Anti-pulmonary oedema reduces pressure in the lungs.

 Chronic heart failure

Chronic heart failure treatment goals

Staging heart failure (NYHA)

The classic method

Alternative method

Grade I

No treatment

No treatment

Grade II

- Physical limitations

Salt diet

- Digital

-Digital + Thiazide Diuretic

- Physical limitations

Salt diet

- Diuretic? ACE inhibitors?

- Diuretic + ACE inhibitors or

Diuretic + vasodilation

Grade III

- Digital + Loop diuretics.

- Digital + Diuretic + vasodilator

- Diuretics + ACE inhibitors or vasodilators

Digital? or

- Diuretics + ACE inhibitors or vasodilators

+ heart medicine?

- Beta-blocker?

- A heart transplant.

Grade IV

- Digital + Diuretic + vasodilator

+ New heart drug

- Heart transplant

 

 Board. Heart Failure Regimen (From M. KOMAJDA and Y. GROSGOGEAT)