What does the cardiovascular system do?

The cardiovascular system (CVS) consists of the heart, lungs and blood vessels. It is responsible for transportation of vital nutrients, gases and hormones throughout the body. The heart functions as the central pump with the blood vessels the pipes of the body. The CVS is controlled by a number of internal and external systems, which keep the CVS in balance with the needs of the body.

The heart is a pear shaped organ positioned centrally within the chest cavity with the apex extending over to the left nipple.  The heart is a divided into a right and left side, each side has an atrium and ventricle.  Heart valves and the contraction of the heart muscle control blood flow through the heart. The right side receives de-oxygenated blood from the major veins of the body and pumps this blood into the lungs.  The left side of the heart then receives oxygen rich blood from the lungs and pumps this blood into the Aorta and arteries of the body.  This pumping action is a complex well-coordinated activity that cannot be fully explained here.    The heart receives its blood supply via the left and right coronary arteries. 

Poor or abnormal function of the cardiovascular system

May be a result of:

• Insufficient blood supply due to dehydration, bleeding or swelling;
• A poor blood supply to the heart, where there is not enough oxygen and other nutrients for its work;
• Poor lung function or obstruction to blood flow in the lungs, which places a strain on the heart muscle;
• Too many or too few electrolytes (eg. potassium, magnesium) that cause irregular heartbeats or dangerous rhythms in the heart.
• Weakness of blood vessel walls.
• Heart muscle weakness

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What is Cardiomyopathy?

There are a wide variety of reasons that cardiomyopathies may develop. The cardiomyopathies can be classified into number of different broad categories. There are also specific cardiomyopathies that exist.

Dilated cardiomyopathy- DCM (see picture B)

• Dilatation and marked enlargement of the heart that leads to impaired pumping of the left or both ventricles. Often referred to as idiopathic due the difficulty of identifying a direct cause. There are four factors associated with DCM: viral, autoimmune, alcoholic/toxic and pregnancy.

. Hypertrophic cardiomyopathy (see picture C)

• Marked left and occasionally right ventricular enlargement, often asymmetrical, which usually involves the interventricular septum. Mutations in certain proteins cause the disease in many patients. It is common for there to be a family history.

Restrictive cardiomyopathy (see picture D)

• In this disorder the heart muscle becomes stiff (but usually not thickened). This restricts the filling of one or both ventricles during the relaxation (diastolic) phase of the cardiac cycle. The heart’s contraction (systolic function) is maintained at normal or near-normal. This may be associated with other disease (e.g., amyloidosis, endomyocardial disease).

Arrhythmogenic right ventricular cardiomyopathy

• Progressive replacement of the right, and to some degree left, ventricular muscle with fibrous and fatty tissue. Familial disease is common.

Ischaemic cardiomyopathy

• This is caused by multiple heart attacks. When a person has had a heart attack or acute myocardial infarction a part of the heart muscle dies and scar tissue is formed. This scar tissue does not contribute to the pumping action of the heart.

Unclassified cardiomyopathy

• Diseases that do not fit readily into any category. Examples include systolic dysfunction with minimal dilatation, mitochondrial disease, and fibroelastosis.

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What happens in Intensive Care/ Coronary Care?

When a person is admitted with a diagnosis of cardiomyopathy the main aims of therapy are to rest the person, to reduce the workload of the heart and to improve the pumping ability of the heart. This treatment is generally drug therapy, which aids in improving the pumping action of the heart muscle and treatment to ensure the proper volume of blood in the body. Patients may be admitted to either an Intensive care Unit or a Coronary Care Unit depending on the situation.

 

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Signs and Symptoms

• Shortness of breath (especially when laying down) due to collection of fluid in the lungs.
• Palpitations – the sensation of feeling the heart beat.
• Dizziness .
• Cough.
• Loss of appetite.
• Increased fatigue and decreased exercise tolerance due to the heart’s inability to increase its workload with increased demand.
• Increased weight and swelling of hands, legs or feet due to fluid retention.
• Low blood pressure due to failure of the cardiovascular system to compensate for the failing heart.
  

Tests that may be done in the intensive Care Unit

Physical examination	Blood tests
Chest X ray	Electrocardiograph (ECG)
Urine tests	Echocardiography

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Treatment options

Treatment of the patient will depend on the severity of their presentation. Patients with mild to moderate symptoms will generally be managed by the cardiac team in a coronary care unit (or combined ICU/CCU). However some patients may present with severe symptoms and may require the full support of an ICU. Close monitoring of vital signs will be done using a bedside monitor and oxygen saturation monitor. In more severe cases an arterial line and a pulmonary artery catheter may be required. Non-invasive ventilation using a CPAP machine (mask attached to a breathing machine) may be used for patients with acute pulmonary oedema. Occasionally a patient will need full respiratory support using an endotracheal tube (breathing tube) and ventilator (the breathing machine). In a number of cases where heart failure from the cardiomyopathy is extremely severe the doctors use mechanical devices to improve cardiac output (amount of blood the heart can pump) such as an intra aortic balloon pump (IABP) or a ventricular assist device (VAD)

Drug Treatments

A variety of drug therapies are used to treat heart failure:

• ACE inhibitors – this group of drugs deceases the workload of the heart by lowering blood pressure and preventing fluid retention by the kidneys;
• Diuretics - increase urine production to treat the fluid retention
• Vasodilators - dilate blood vessels which decrease the workload of the heart;
• Beta blocking agents - slow the heart rate and this decreases the workload of the heart;
• Antiarrhythmic drugs - keep the heart in a normal heart rhythm;
• Inotropic drugs -strengthen heart contraction

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The time that the person will remain in Intensive Care or Coronary Care will vary depending on the prognosis of the patient. The prognosis of patients with heart failure depends primarily on the nature of the underlying heart disease and if the precipitating factor bringing the person into hospital can be treated effectively. Some patients with severe heart failure may require to be put on a waiting list for a heart transplant. The team of specialist doctors and Nurses working in the Intensive Care Unit will be able to help give you information on each specific case.

Internet Links

• NSW health Internet
• Heart Health and Cardiac Rehabilitation (includes translation to Arabic, Greek, Italian, Russian and Spanish)
• National Heart Foundation - Australia
• National Heart Foundation - New Zealand
• British Heart Foundation
• Heart Beat Victoria

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