Heart Failure

 

Heart failure:

The human heart is divided into 4 chambers, two upper chambers receives blood and two lower chambers - right and left ventricles discharge blood and are muscular in nature and called muscular pumps. The right ventricle sends venous blood to the lungs for collecting fresh Oxygen and discharge Carbon dioxide. The distance between the right ventricle and lungs is short and right ventricle has to generate just enough pressure to send blood in the pulmonary capillaries.

The left ventricle is responsible for sending fully oxygenated blood and nutrients to very cells of the body and requires to generate much higher pressure and has a thick muscular wall.

The failure of one or both ventricles to send blood out to their respective destinations happens when ventricular muscles become weaker. This is in medical term called heart failure; it may happen only on the right side then it is called Right ventricular failure and likewise, when only left ventricle fails is called left ventricular failure. Often, one ventricular failure progress to both heart failures and also both hearts may fail simultaneously. If heart failure happens suddenly it is called acute heart failure – either acute right hear failure or acute left heart failure. And when heart failure develop over the years is called Chronic Heart failure – chronic right heart failure or chronic left heart failure or simple heart failure. Heart failure or ventricular failure is the same; and one term is used for the other quite frequently.

The cause of heart failure:

Blood is the vital fluid, circulation of blood to every cells of the body is the only function of the heart. But if there is no blood in the body or marked loss of blood then even the best heart fails.

Those conditions will not be discussed here.

Heart fails for various medical conditions and due to congenital or acquired structural abnormalities.

1. Coronary artery disease.

Ventricles of the heart are full of blood but unable to use that blood for their oxygen and nutritional requirements. Coronary arteries supply blood to the heart. Coronary artery disease is the most common reason heart fails to supply blood to the heart. It may happens suddenly – known as acute coronary event and unless immediate hospital treatment, devastating result follows ; heart may fail slowly over the years – in this situation angina pectoris ( pain in heart) is the main symptom. Then heart muscles slowly weaken and fails.

High BP, high cholesterol, obesity, genetic predisposition, and diabetes are risk factors for the development of coronary artery disease. Initially the endothelial cell damage, separates cells and serum sips underneath the endothelial lining. A waxy deposit forms, pushing it inside the lumen of the vessel, blood flow slows and that manifests as angina pectoris. From time to time the waxy plaque breaks and sends the tissue derbies further into smaller arteriole and precipitates a heart attack. In the raw are of the wall- the site of plaque break, platelets accumulate to plug the raw area by forming a platelet clot, followed by blood clot develops and block off the coronary artery. 

2. Diabetes mellitus.

This condition is steadily increasing all over the world as more and more people are consuming factory produced prepackage food. Diabetes produces microvascular changes in the coronary vessels and many other organs. Plaque formation in coronary artery leads to heart attacks as described above.

{wish to know how DM produce microvascular changes....https://humihealth.blogspot.com/2022/01/diabetes-mellitus-and-microvascular.html }

High BP effects ventricular muscles to undergo hypertrophy in order to over come resistance offered by high BP. Coronary arteries pass through the layers of the heart muscle and every time ventricles contact the coronary artery is pinched off. More higher BP means more pinching and less and less blood flow to the ventricles. If high BP is not controlled heart muscles weaken and fail.

These three above conditions are the main causes of heart failure.

   4. Pulmonary embolism.

Deep seated veins of the thigh and pelvis under certain conditions spontaneously develop blood clots. Venous clots are fragile and easily break off and are carried by the venous blood to the right side of the heart. Right ventricle pushes these clots into the pulmonary artery and the clots block pulmonary arterial circulation. Patients experience severe chest pain and palpitation begins to sweat and soon go into shock. Blood returning to the left ventricle from the lungs are markedly undersaturated and patients develop central cyanosis. Symptoms of hypoxemia soon followed by cardiac arrhythmias and shock which does not reverses with bet adrenergic drugs and other measures. Death follows hours or in a day or two.

The above 4 are also examples of output failure of the ventricles.

5. Cardiac tamponade and pericardial effusion.

When the pericardial cavity is filled with blood because of a direct injury or due to rupture of the heart from other causes, there is little space remains in ventricles to receive blood. This condition produce stagnation of blood in pulmonary circulation and followed by systemic circulation. Cardiac arrhythmia and shock soon follows.

6. Constrictive pericarditis.

Certain infective pericarditis ends in thickening the pericardium and sometimes develop calcification. The symptoms produced in this condition is not that dramatic but never the less serious enough to threaten life of a patient if prompt treatment is nor forthcoming.

7. Myocarditis and dilated cardiomyopathy.

Virus commonly produce myocarditis are Adenovirus, Parvovirus B19, Human Herpes virus 6, Epstein -Barr virus, Human Cytomegalovirus and Enterovirus. Initial inflammatory cell infiltration of the myocardium is followed by fibrosis. The ventricular muscles become weak and unable to meet body's demand and heart fails. In this condition dilated cardiomyopathy and atrial fibrillation and ventricular fibrillation may end life earlier than heart failure.

8. Subacute bacterial endocarditis.

Streptococcus viridans infects damaged or deformed heart valves – mitral and aortic valves are mostly bacterial growth. This produce further damages to valves and other venerable ventricular structures and systemic sepsis leads to organ failure and deaths.

Staphylococcus and many other bacteria and fungus are capable of causing myocarditis and more easily damage heart structures.

9. infiltrative diseases of the heart.

Like inflammatory cells, other substances like iron, copper, and amyloid- a proteinaceous materiel, infiltrate ventricular muscles. This interferes ventricular functions and eventually the heart fails.

10. Radiation and chemotherapy.

Doxorubicin and other chemotherapy drugs and radiation therapy are cardiotoxic and ultimately produce cardiac fibrosis and heart failure.

Examples 5 to 10 are also considered diastolic dysfunction of ventricles (defect in receiving blood).

Other less common but significant causes of heat failure.

1. Morbid obesity and Kyphoscoliosis.

The way the heart function normally, requires free movements inside the chest cavity, as it beats. These two examples and several conditions put stain on the heart and the right ventricle fails first.

2.Malignancy.

Tumors of the heart is rare. Rarely sarcoma of heart is encounter. It is not an easy task to care for.

3. Congenial defects of the heart.

The advent of Doppler Sonography makes it possible to examine a developing child in utero and if there are structural defects of the heart that can be surgically repaired at that time or shortly after birth. This has eliminated many instances of heart failures. Just to mention some well known congenital heart lesions are Atrial Septal Defect (ASD), Ventricular Septal Defect (VSD), Pulmonary Stenosis (PS), Fallot Tetralogy and Transposition of Great Vessels. Hypertrophic cardiomyopathy is congenital but symptoms starts at age 16 -18. In congenital anomalous origin of coronary artery arising from coronary sinus, venous blood circulates myocardium. In postpartum the baby fails to thrive and die if the condition is not recognized soon enough. 

4. Acquired heart valve defects.

Rheumatic fever, at an earlier times, produced havoc with the lives of many young individual. The streptococcus sore throat is the initial illness followed by 2 weeks later by joint pain and heart murmurs, Mitral valve is always affected and often associated with Aortic valve

5. Atrial fibrillation and ventricular fibrillation.

These two heart rhythm abnormalities are seen less frequently in otherwise younger healthy individual and consider as diseases of the old. However, cocaine, amphetamine and cannabis users they are distinct heath hazard. When ventricles pump 250 -300 beats per minute, these is hardly time blood to enter the ventricles and cardiac output falls precipitously. It does not take much for patients to loos consciousness and without treatment die from shock. In ventricular fibrillation, heart does not actually contract and blood remains in the cavities of the ventricles and  blood circulation ceases.

 The New York Heart Association classified heart failure into 4 categories based on the severity of the symptoms. In category 1 - patients have minimal symptoms, in category IV - patients are bed ridden and totally depended on others for the activities of daily living. Category II and III are in between category II and III.

This list of causes of heart failure is short , conditions which are not primarily cardiac are not included in this article.

This bog may be better understood if a previous blog -Human Heart is also reviewed at the same time.

https://humihealth.blogspot.com/2019/03/the-heart-and-heart-failure.html   (Copy and paste on your browser).

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Toxoplasma gondii

         Toxoplasma gondii infection

                     P.K.Ghatak, MD 

Toxoplasma gondii

Toxoplasma gondii is a protozoa. It lives in cat's intestine as a parasite and is eliminated from cats' body in the feces in a cystic from which can infect mammals and birds. Rodents and small mammals are intermediate and humans are also intermediate host and victims.

Toxoplasma needs a higher concentration of arachidonic acid, a long chain fatty acid, for sexual maturity and reproduction. All species of cat family provide that environment because the enzyme, delta-6-desaturase (D6D), which breaks down arachidonic acid during metabolism, is lacking in he cats' small intestine.

Toxoplasmosis is a medical term describing clinical features of Toxoplasma gondii (T. gondii) infection T. gondii is an obligate intracellular parasite in human and other mammals.

Eating under cooked meat, raw fruits, vegetables and drinking unfiltered water contaminated with cats feces are the main source of human infection. In rare cases blood transfusion, organ transplantation and transplacental infection to the developing fetus can occur. Most infected people show no symptoms, however, the fetuses of women infected for first time during pregnancy and Immunosuppressed people become sick.

There are three infectious forms of T. gondii, - 1.sporozoites - present in the feces of cat as oocysts ( thick wall cysts containing multiple larvae), 2.tachyzoites ( rapidly multiplying by asexual cell division) and 3. bradyzoites (slow growing or dormant) - present in the muscles and organs of infected mammals.

Life cycle of Toxoplasma.

T. gondii has a complex life cycle.

In cats:

All species of cat family are carnivorous , when they devour infected preys , the cysts are released in the small intestine. The wall of the cysts opens and releases sporozoites. Subsequent development of T. gondii takes two different pathways.

1. As a intestinal parasite.

In 3 to 10 days the sporozoites mature as male and female gametes and after mating and begins to reproduce. Million of cysts are excreted daily in the feces for 14 days. In the soil these cysts matures further and becomes infectious in a day or two. The cysts can survive about a year in the soil and water

2. As cysts in muscles and organs,

Some of the released sporozoites penetrate intestinal wall and are carries by the blood to different organs and muscles. The sporozoites asexually divide rapidly and are called tachyzoites. Later, tachyzoites stop dividing and form cysts and are known as bradyzoites. Cysts in the muscles, heart,eyes and other organs can complete their life journey if other carnivores eat the cat.

In rodents, mammals and human:

Infection is via oral route. In the intestine the T. gondii follows the 2nd path described for cat.

                                         Taken from CDC publication.

Primary infection is healthy adults.

About 50% of infected people have no symptoms , the rest have symptoms resembling a flu with slight fever, body aches, cough and sneezing. Cervical lymph node enlargement is a distinct feature, at times, lymph nodes draining the thorax may enlarge. Viral pneumonia like symptoms may develop in some. Rarely skin lesions of various definitions are also described. Cysts, containing a live T. gondii remain in the muscles, brain, heart, eyes and other organ for the rest of the life of an individual.

Pregnancy:

In the first trimester of pregnancy if a woman is infected, there is a good chance that infection from the placenta will pass to the fetus. This may result in a miscarriage and spontaneous abortion. A growing fetus examined by ultrasonography shows growth retardation and a characteristic triad of hydrocephalus, chorioretinitis and areas of calcification of the brain. Eye infection leads to congenital blindness. And sensory deafness in 30% cases.

In last trimester of infection produces mainly blindness.

Latency:

In all healthy people, T. gondii after the initial infection, remains in an inactive state. The organism however is still alive within the cysts and last for the rest of life of the individual.

Reactivation:

When inter-current infections and HIV infection in particular, lowers the cellular resistance or immunosuppressed drugs are used, the cellular resistance breaks down and T. gondii spread through out the body. The CNS and eye symptoms predominate.

The Brain:

Mass lesions, like cerebral lymphoma , are present in many cases; in most of the cases necrotizing lymphocytic vasculitis and microglial nodules around the cysts are present. These produce seizures and symptoms of encephalitis. The common areas of brain are the symmetrical lesions in the white matter of cerebral cortex, thalamus, brain stem, and cerebellum. Symptoms are headaches, confusion, seizure, inability to concentrate, clumsiness of movements, fever and nausea and vomiting.

Eyes:

Necrotizing lesions of choroid and retina of the eyes produce poor vision and blindness.

Diagnosis:

The initial test is IgM and IgG antibodies against T. gondii. If a biopsy is performed the T. gondii is visible within the cells. In most cases, PCR test to detect DNA of T. gondii has become a standard test. In encephalitis the PCR test of CSF is 100% positive .

In suspected mother to fetal transmission, an amniocentesis and PCR test is performed on the amniotic fluid.

Treatment:

Normal adult people with T. gondii infection requires no medication. In a developing fetus, even infection is confirmed, no anti- protozoal drugs are prescribed because of adverse effects. After the birth of the baby the choice of therapy is a combination of Pyrimethamine and Sulfadiazine. Infections of pregnant women if the child is not infected - Spiramycin is preferred therapy. If the child is infected then no treatment is given to mothers in the first trimester because drugs can cause deformed brain development and low platelet count of the child. After 16 weeks of pregnancy, Pyrimethamine and Sulfadiazine plus folinic acid are prescribed.

In all other infections the drug of choice is a combination of Pyrimethamine and Sulfadiazine; Folinic acid is added to prevent anemia.

Children with congenital deafness 16 months of therapy is advocated.

Prophylaxis in HIV infection and immunosuppressed individual.

Pyrimethamine plus Sulfadiazine should be continued.

Vaccine:

No vaccine is available.

Prevention:

Good hygienic measures and avoiding under cooked meat and unwashed fruits and vegetable.