Question

A 45-year-old male is transferred from the Emergency department of a NYC hospital into the critical care setting. At arrival he requires initiation of mechanical ventilation due to Acute Respiratory Distress Syndrome (ARDS). Invasive hemodynamic monitoring is started with an EV1000 Monitor. He works as an International Business manager and recently traveled to Madrid, Spain and Berlin, Germany. At arrival he conducted with auto isolation due to the COVID-19 public health sanitary emergency. At 5 days from arrival he started with fever and dry cough. He got in contact with his family physician and stayed at home with general support measures but on day 7 he started with shortness of breath and arrived at the Emergency setting of this NYC hospital. As important medical background the patient has a previous diagnosis of Chronic Arterial Hypertension of 5 years in treatment with Losartan and Insulin resistance syndrome in treatment with diet and exercise. On the third day under mechanical ventilation and invasive hemodynamic monitoring the patient starts with hemodynamic signs of myocarditis with acute cardiac failure and cardiogenic shock.

If the patient started with Low blood pressure and is managed with an INTRAVENOUS infusion of crystalloid solutions (Hartmann IV solution), explain the physiological mechanisms that would get activated, include the order (sympathetic, parasympathetic, baroreceptors, Bainbridge reflex, frank starling).  Explain the factors that determine stroke volume and pressure. Explain Myocarditis (Reasoning: Symptoms/Epidemiology/Etiology/Risk Factors/Pathophysiology/Laboratory and/or Support Studies).

Answer 1

Though patient admitted with Respiratoy distress syndrome with previous history of Chronic Arterial Hypertention, on the third day of his admission the patient starts with the symptoms of myocarditis with acute cardiac failure and cardiogenic shock.

Myocarditis: is a viral infection caused by the inflammation of middle layer of cardiac muscle known as myocardium.

Symptoms: Shortness of breath,severe chest pain, fatigue, tiredness, rapid cardiac rhythms,swelling of legs,ankles and feet. Other symptoms include severe body ache, headache, joint pain, fever,sore throat and diarrhea.

Epidermiology: The incidence of myocarditis is approximately 1.5 million cases arround the world in a year. It is estimated that 10-20 cases per 100,000 persons are detected.

Etiology:

Viruses: Many viruses such as adenovirus, hepatitis B and C virus,herpes simplex virus

Bacteria: Many bacterias such as staphylococcus, streptococcus

Fungi: Candida,aspergillus and histoplasma

Parasites: Trypanosoma cruzi and toxoplasma

Other factors include:    * Certain medications which is used ti trae cancer, anti seizure drugs, antibioyics

                                   * Exposure to radiation or checimals leads to myocarditis

Risk factors: Weak immune system, drug such as cocaine, previous history of myocarditis

Pathophysiology of myocarditis

Any viral infection that can lead to inflammation and injury results in dysrhythmias leads to congestive heart failure. Due to decreased Myocardial contractility heart enlarges cause pulmonary edema leads to congestive heart failure.Increased sympathetic tone and decresed cardiac can lead to Myocarditis

Lab findings:

* elevated CK, LDH

* EKG- sinus tachycardia, reduced QRS voltage, ST- segment and T -wave abnormalities,arrhythmia

* Echo: poor ventricular function,pericardial effusion, mital valve regurgitation

Diagnosis : MRI, ECG, Echocardiogram, Chest X-ray, cardiac catheterization

Treatment:

* ACE inhibitor enables to relax blood vessels,lowers blood pressure and prevents diabetes related kidney disease.

* Beta blocker slows heart rate and decreases blood pressure.

* Diuretics enables to eliminate extra water from the body

* Anti-arrhythmic helps to control abnormal heart rhythms.

Factors that affect stroke volume are Preload, Contractility and Afterload.The filling pressure of heart at the end od diastole is known as preload. The vigorous contraction of heart muscles during systole is contractility.The pressure against which heart eject blood during systole is known as afterload.

The other factors which influence blood pressure are cardiac output, blood viscosity, elasticity of vessels walls, volume of circulating blood.

    Physiologial Mechanisms

Baroreceptor: It is one of the body mechanism which helps to maintain blood pressure at constant levels.The decreased blood pressure decreases baroflex activation and increase heart rate of the body.

Frank Starling: It indicates the relation between stroke volume and diastolic volume. The stroke volume of heart increases when the volume of blood increases.

Bainbridge reflex: is an increase in heart rate beacause of the increase in central venous pressure.

Sympathetic and Parasympathetic: The sympathetic nervous system prepares the body to response in any danger situation. The parasympathetic system protects body from over working and keep the body in calm and relaxed state.