Circulation part 3

A wide range of medical and traumatic conditions can affect the circulatory system. Here we’ll look at some of the more common pre-hospital conditions that can have a detrimental effect; 

Myocardial Infarction (MI) – An MI is where a coronary artery becomes occluded by a blood clot. This starves a section of the heart, causing it to become hypoxic, and cardiac tissues to die. As heart cells die, the ability of the heart to pump blood becomes affected. The site of the clot and area of affected tissue will determine how quickly the heart begins to fail. Identification of an MI can be made through the patients’ history, signs and symptoms such as chest pain, shortness of breath, radiating pain to the jaw or arm, and ST-elevation on an ECG.  

Sometime, the classical heart attack presentations aren’t always the case, and an MI may be occurring without several of the typical presentations. The patient will require transport and definitive care at a Primary Percutaneous Coronary Intervention centre, although this may be different depending on area and local guidelines. An array of medications can be given to the patient to try and reduce the damage of the MI and offer pain relief. These can include Aspirin, Clopidogrel, GTN, and Morphine.   

Angina – Angina is chest pain caused by myocardial ischaemia when blood oxygen supply cannot meet the demand of the heart cells. The difference to an MI is that it is not a full occlusion of the coronary artery and is due to the narrowing of the arteries. Typical signs and symptoms of Angina can include chest pain, shortness of breath, radiating pain to the jaw or arm, and ST segment depression on an ECG.  

There are several Angina types; Stable Angina is where pain may come on due to stressful or exacerbating situations, such as exercise, and is often relieved by medication. Unstable Angina is where pain may come on at rest and is sometimes not easily managed by medication. Unstable Angina puts the patient at higher risk of an MI. Decubitus Angina is where pain comes on when the patient is lying flat, this is due to increased cardiac filling pressures which may lead to an augmented myocardial wall tension, subsequently increasing oxygen demand. Prinzmetal’s Angina is caused by coronary artery spasm, limiting the supply of blood to the heart. In the emergency pre-hospital context, a patient calling with chest pain will require 12-lead ECG, Coronary Artery Disease (CAD) medication to help alleviate the symptoms such as Aspirin, GTN, Morphine, and transport to hospital for further investigations.   

Heart Failure – Heart failure is when an aging or damaged heart is unable to pump blood effectively to meet the demands of the body. Depending on the effected side, pathophysiological symptoms can vary. Left Ventricle Failure (LVF) symptoms can include dyspnoea, tachypnoea, tachycardia, orthopnoea, dry nocturnal cough, coughing up pink frothy sputum, and basal lung crepitus. This is due to the back up of fluid within the pulmonary artery from the inadequate pumping of the left side of the heart. Right Ventricle Failure (RVF) symptoms can include peripheral oedema, sacral oedema, abdominal distention, engorgement of the face, pulsation in the neck and face, and distended varicose veins. This is due to the back up of fluid within the Vena Cava and venous return to the heart from inadequate pumping of the right side of the heart. Congested Cardiac Failure (CCF) typically presents with a combination of LVF and RVF symptoms due to both sides being affected. A patient with LVF and/or CCF who is suffering from pulmonary oedema and dyspnoea may benefit (as discussed in the Breathing section) from GTN administration and Furosemide. An exacerbation in all heart failure cases may have significant circulatory disruption and will require urgent transport to hospital.   

Shock – Shock can be described as the physiological or psychological response to inadequate tissue oxygenation, where the metabolic needs of cells are not met due to inadequate blood flow. There are a number of different types of shock; 

Hypovolaemic – due to low blood volume 

Cardiogenic – where the heart isn’t pumping effectively 

Distributive – where body fluids are redistributed from where they should be to another body cavity such in cases of anaphylaxis or burns 

Neurogenic – where the nervous system isn’t managing constriction of blood vessels effectively in cases such as trauma affected patients or patients with nervous system problems 

Septic – caused by severe infection and displacement of fluids 

Obstructive – caused by an obstruction of a major vessel or vessels within the body, meaning all of the tissue past the obstruction is not receiving adequate blood flow or perfusion 

Each can be managed by IV Fluid replacement and further supportive/medical treatments, however, different types have different indications, contra-indications, and cautions to consider, so review your medications and treatment guidelines for your own area.   

Cardiac Arrhythmias – There are wide range of cardiac arrhythmias that can affect circulation. Each type of arrhythmia can affect a patient differently, and treatment can range from primary-led care, to emergency care and resuscitation.