Chapter 4: Assessment and Observation of the Cardiovascular System

Introduction

The cardiovascular system is one of the body's fundamental life-sustaining systems; therefore, it is essential that nurses are able to accurately and comprehensively assess this system. This chapter introduces the fundamental knowledge and skills nurses require to do so. It begins with an overview of the fundamental anatomy and physiology of the cardiovascular system. The chapter then explains the processes involved in collecting a general health history for the cardiovascular system, and in performing a physical examination of the cardiovascular system. Finally, this chapter considers a number of special observation and assessment techniques which may be used in the physical examination of the cardiovascular system.

Important note

This section of the chapter assumes a basic knowledge of human anatomy and physiology. If you feel you need to revise these concepts, you are encouraged to consult a quality nursing textbook.

Fundamental anatomy and physiology of the cardiovascular system

The cardiovascular system is comprised of the heart and the system of vessel which transport blood (containing oxygen and nutrients) to, and metabolic wastes from, all parts of the body. It is a dynamic system, with the capacity to adjust to changing conditions and demands (e.g. exercise, temperature changes, stress, etc.). The cardiovascular system does this by, for example, constricting and dilating blood vessels and altering cardiac output, etc.

The heart is the organ responsible for moving blood, oxygen and nutrients around the cardiovascular system. It is a pump comprised of four chambers - two atria (smaller top chambers) and two ventricles (larger bottom chambers). The right side of the heart receives deoxygenated blood from the body via the superior and inferior vena cavae, and pumps it into the pulmonary circulation (i.e. to the lungs) for reoxygenation. Deoxygenated blood leaves the heart via a large vessel known as the pulmonary artery. The left side of the heart receives oxygenated blood from the pulmonary veins, and pumps it into the systemic circulation (i.e. to the body) for use. Oxygenated blood leaves the heart via a large vessel known as the aorta.

There are four valves which control the flow of blood through the chambers of the heart:

• The two atrioventricular valves (separating the atria from the ventricles), including the tricuspid valve (on the right) and the mitral valve (on the left).
• The two semilunar valves, including the pulmonary valve (separating the right ventricle from the pulmonary artery) and the aortic valve (separating the left ventricle from the aorta).

As you saw earlier in this section of the chapter, the heart is the organ responsible for moving - or, more accurately, pumping - blood, oxygen and nutrients around the cardiovascular system. The term 'cardiac cycle' is used to describe the processes involved. There are two key phases of the cardiac cycle:

• Diastole - during this phase, the ventricles relax and fill with blood from the atria. The movement of blood from the atria to the ventricles, through the atrioventricular valves, occurs because the pressure of the blood in the atria is higher than the pressure of the blood in the ventricles, and the atria also contract to facilitate this process. At the end of diastole, the ventricles are filled with blood.
• Systole - during this phase the ventricles contract, forcing blood through the semilunar valves and into the pulmonary artery (from the left ventricle) and the aorta (from the right ventricle). At the end of systole, the ventricles are mostly emptied of blood.

The cardiac cycle, as described above, is controlled by the heart's electrical conduction system. At the beginning of each cardiac cycle, an electrical impulse originating in the sinoatrial node (at the top of the heart) travels across the heart to the atrioventricular node (in the centre of the heart), down the 'bundle of His' and through the 'Purkinje fibres' (at the base of the heart). The movement of this electrical impulse through the heart results in the contraction of the atria and then the ventricles.

When oxygenated blood leaves the heart at the end of each cardiac cycle, it enters the peripheral vascular system - that is, the system of vessels that takes blood to (and then from) the tissues. The arteries are the vessels which carry oxygenated blood to the body; blood moves through these vessels via the pressure generated with each contraction of the ventricles. The veins are the vessels which carry deoxygenated blood back to the heart; blood moves through these vessels via a series of passive valves. Small vessels called capillaries permeate, and allow blood to perfuse every part of the body.

It is important to note that the lymphatic system works in tandem with the cardiovascular system; therefore, in assessing the cardiovascular system the nurse is also indirectly assessing the lymphatic system. The lymphatic system is the network of nodes and associated structured designed to move lymphatic fluid through the interstitial spaces. It has a variety of functions, but a particularly important role in the immune system.

Cardiovascular system - focused health history

As you saw in the previous chapter of this module, health observation and assessment involves three concurrent steps:

When assessing a patient's cardiovascular system, the nurse must commence by collecting a health history. This involves collecting data about:

In some cases, a person will present with a specific problem related to their heart (e.g. chest pain, dyspnoea, cough, nocturia, fatigue, syncope, oedema, leg pain, etc.). If this is the case, a nurse must gather a more focused health history. Remember, nurses can assess a patient's symptoms using the strategy remembered by the 'OLD CARTS' mnemonic (introduced in a previous chapter of this module).

Chest pain is a particularly significant symptom indicating dysfunction in the cardiovascular system. If a patient complains of pain, they should be rapidly assessed using the strategy remembered by the 'PQRST' mnemonic (introduced in a previous chapter of this module). The location, quality, quantity, chronology, associated manifestations and aggravating / alleviating factors of the chest pain a patient experiences can provide important information about the cause of this pain - and allow the patient's health care team to make a differential diagnosis. Review the information in the following table:

As highlighted in the above table, unstable angina and myocardial infarction have very similar signs and symptoms. The key assessment a nurse may perform to differentiate between these conditions is an electrocardiogram (ECG). You will study ECGs in detail in a later section of this unit.

It is important for nurses to realise that there are a number of conditions not related to the cardiovascular system which may result in chest pain. These conditions include (but are not limited to):

• Panic disorder, a condition where a patient experiences recurrent, disabling panic attacks with respiratory and cardiovascular symptoms (e.g. chest pain, dyspnoea, heart palpitations, diaphoresis, nausea, trembling, etc.).
• Peptic ulcer disease, a condition where there is a break in the lining of the stomach, often caused by a bacterial infection or the use of anti-inflammatory medication.
• Gastro-oesophageal reflux disease (GORD), a condition where the lower oesophageal sphincter fails to close properly, and acid from the stomach leaks into, and erodes, the oesophagus.
• Costochondritis, a condition involving inflammation of the cartilage where the ribs attach to the sternum.

As you collect a general health history from a patient, it is important that you assess and identify risk factors for: (1) hypertension, and (2) coronary artery disease. These are two of the most common cardiovascular diseases in the United Kingdom. The common risk factors of each are listed in the table below:

It is important to highlight that some of these risk factors for cardiovascular disease are non-modifiable (e.g. age, family history, gender); however, many are modifiable - that is, a person is capable of making changes to them to reduce their risk. As part of their fundamental health promotion role, it is important that nurses are able to provide patients with advice about how to address the risk factors identified during assessment.

Cardiovascular system - physical examination

Once a cardiovascular health history has been obtained, as described in the previous section of this chapter, a nurse may commence a physical examination of the patient's cardiovascular system. A stepwise process of physically examining the patient's cardiovascular system, with normal (expected) and common abnormal findings, is presented in the following table:

As you saw in the above table, assessing the heart sounds is a key skill for nurses. There are two normal heart sounds: S₁, at systole, has a low pitch, and S₂, at diastole, has a higher pitch. However, there are a number of abnormal sounds a nurse may identify during their assessment; read the information in the following table:

Abnormal heart sounds are often referred to as 'murmurs'. They are generally classified into one of two types:

1. Diastolic murmurs occur during diastole, or the period when the ventricles contract and fill with blood. Most diastolic murmurs are caused by obstructions to the movement of blood into the ventricles, often due to problems with the semilunar and / or atrioventricular valves.
2. Systolic murmurs occur during systole, or the period when the ventricles contract and eject blood. Most systolic murmurs are caused by obstructions to the movement of blood out of the ventricles, often due to problems with the semilunar and / or atrioventricular valves. Other common causes of systolic murmurs are structural deformities of the pulmonary arteries and / or the aorta, structural deformities of the cardiac muscle (e.g. septal defect), severe anaemia, and thyrotoxicosis, etc.

Special assessment techniques for the cardiovascular system

There are a number of special assessment techniques particular to the cardiovascular system:

• Electrocardiogram (ECG). As you saw in an earlier section of this chapter, a key tool to assess the cardiovascular system, and one which can be particularly useful in assisting with a differential diagnosis, is the ECG. An ECG is a measurement of the electrical activity in the heart during a cardiac cycle. An ECG recording is made using an ECG machine, with a number of probes (referred to as leads) attached to the skin around the patient's heart and to their peripheries. Nurses should refer to the particular machine used by their organisation to determine the correct placement of ECG leads.

An ECG machine depicts a cardiac cycle as illustrated in the image following (note that an ECG records multiple cardiac cycles over a period of time):

As noted, in an earlier section of this chapter, an ECG is the key assessment a nurse may perform to differentiate between unstable angina and myocardial infarction - conditions with very similar signs and symptoms. Essentially, myocardial infarct is apparent on an ECG, often - though not always - with changes to the section of the ECG recording between the S- and T-sections (indicative of an ST-segment myocardial infarct, or 'STEMI'). Angina is not apparent on ECG.

It is worth noting here that the interpretation of ECG measurements can be very complex. In the UK, it is generally the responsibility of suitably-trained medical practitioners to interpret ECG measurements and, subsequently, make diagnoses. However, it is important for nurses to be able to identify obvious problems evident on an ECG recording - such as STEMI, described above.

• Capillary refill time (CRT). Another simple, but very important, assessment technique unique to the cardiovascular system is capillary refill time, often abbreviated to 'CRT'. Measuring CRT allows a nurse to assess the function of a patient's vascular system at the level of the capillaries. A nurse measures CRT by gently squeezing the pads of a patient's fingers, or their nail beds, until they blanche (whiten). The pressure is then released and the time for the capillaries to refill, or the colour of the pads / nail beds to return to normal, recorded. CRT should be should be ≤2 seconds.
• Pitting oedema. This is an assessment technique which may identify problems with the cardiovascular system and / or the lymphatic system - specifically, fluid retention and swelling of the tissues. When assessing for pitting oedema, the nurse gently presses the pads of their first and middle fingers into the tissue covering the bottom half of the patient's shin. If an indentation remains after the nurse's fingers are lifted, pitting oedema is present. Pitting oedema is scored as follows:

It is important to highlight that, in most clinical settings, the depth of pitting oedema is not measured. However, nurses should be confident in estimating the depth of the pitting oedema which they observe on a patient during assessment.

• Clubbing of the fingers. This occurs when the angle of the base of the nail bed, where it joins to the tissues of the fingers, is >160. Clubbing is very obvious on inspection, and does not need to be measured. Clubbing indicates that a patient may be experiencing chronic hypoxia.

It is important for nurses to note that there are a variety of other supplementary techniques which may be used to assess the cardiovascular system. Additional assessments to assist with differential diagnosis of cardiovascular problems include chest X-rays or CT scans, blood tests to assess for cardiac biomarkers (i.e. chemicals, such as troponin, which are released into the blood after damage to the heart muscle), and perhaps ultrasound. Although nurses generally do not perform these assessments, they have an important role in preparing the patient and in interpreting and communicating relevant findings.

Conclusion

As you have seen throughout this chapter, the cardiovascular system is one of the body's fundamental life-sustaining systems; therefore, it is essential that nurses are able to accurately and comprehensively assess this system. This chapter has introduced the fundamental knowledge and skills nurses require to do so. It began with an overview of the fundamental anatomy and physiology of the cardiovascular system. The chapter then explained the processes involved in collecting a general health history for the cardiovascular system, and in performing a physical examination of the cardiovascular system. Finally, this chapter considered a number of special observation and assessment techniques which may be used in the physical examination of the cardiovascular system.

'Hands-on' scenario

The observation and assessment of a patient experiencing chest pain, to develop a differential diagnosis

Melissa is a graduate nurse working in the Accident and Emergency (A&E) Department of a large hospital in London. She is preparing to receive a patient arriving via road ambulance. The only information Melissa has about this patient is that he is a fifty-nine year old male who is experiencing chest pain, which the attending paramedics believe to be of cardiac origin. Melissa's role in the care of this patient will be to assist in his assessment - including (1) collecting a health history and (2) physically examining the patient. Because the patient's chest pain is believed to be of cardiac origin, Melissa's health history and physical examination will focus on the cardiovascular system.

The patient is transferred from the ambulance receiving area and into a critical care bay in the A&E Department. Melissa immediately begins observing the patient. She firstly looks for any issues which may immediately threaten the life or wellbeing of the patient. Melissa notices that the patient is conscious and alert, though he is clearly experiencing significant discomfort. He has an oxygen mask in-situ, and is dyspnoeic with clear intercostal retractions and accessory muscle use. The skin of his face, upper extremities and torso appears pale, mottled and diaphoretic.

Melissa begins the first stage of the assessment process - the collection of a health history. In this case, the health history is provided by the paramedic who attended to the patient in the community. Because of the acuity of the situation, the paramedic provides only the information which is necessary for the patient's immediate care. The paramedic tells the A&E team:

"This is Mr Donald Jones. He is a fifty-nine year old male. Approximately twenty minutes ago, Donald's wife telephoned paramedics to state that Donald was experiencing chest pain of sudden onset whilst he was sitting watching television. The pain is located in the precordial region, radiating into both arms, the jaw and the epigastric region. Donald describes this pain as 'squeezing' and 'crushing', at 10/10 on the pain scale. Donald is also experiencing dyspnoea and nausea. Donald has no significant past medical history. Donald is receiving 8 Litres of oxygen per minute via a nasal mask. He has had 15 milligrams of intravenous morphine during transport, but he states that his pain remains at 10/10. An ECG was performed during transport, and is attached to Donald's notes."

As Melissa is listening to this health history, she progresses to the next stage of the assessment process - the physical examination, with a focus on the cardiovascular system. Prior to commencing her assessment, Melissa provides Mr Jones with a brief explanation of what she plans to do and why, and obtains Mr Jones' consent. Melissa then commences the physical examination. Because of the urgency of the situation, she focuses her physical examination as follows:

The health history and physical examination provide Melissa with important information about the current state of Mr Jones' cardiovascular system, and the possible causes of his chest pain. From the heath history, she learned that Mr Jones' chest pain occurred suddenly, whilst the patient was at rest; Melissa knows the most common causes - but not the only causes - of such pain are myocardial infarction and unstable angina. From her physical examination, Melissa also knows that Mr Jones' heart is working harder than normal (evidenced by Mr Jones' tachycardia and hypertension), but that it is failing to compensate for the dysfunction that is occurring (evidenced by Mr Jones' pale and mottled skin, his significant dyspnoea, his cyanosis, his CRT >2 seconds and his low oxygen saturation). However, although it has provided useful baseline information, so far the physical examination has not provided Melissa with any further information which could inform a differential diagnosis; this is because the data Melissa has collected during the physical examination could relate equally to myocardial infarction OR unstable angina.

For this reason, Melissa looks at another key tool to assess the cardiovascular system, and one which can be particularly useful in assisting with a differential diagnosis - the electrocardiogram (ECG). An ECG was performed by the paramedics, and Melissa accesses the printout. She identifies changes to the section of the ECG recording between the S- and T-sections - these changes are characteristic of an ST-segment myocardial infarct, or 'STEMI'. These changes would not be apparent if Mr Jones was experiencing unstable angina, or any other disorder - either related to the cardiovascular system, or not - which causes chest pain.

Although myocardial infarction generally, and STEMI specifically, place a patient at significant risk of disability and death, Melissa knows that rapid and appropriate intervention can significantly improve outcomes. Melissa's contribution to Mr Jones' assessment - including the collection of a health history, and physical examination - enabled: (1) a comprehensive current state of Mr Jones' cardiovascular system, and (2) a diagnosis of the cause of his chest pain. This allows rapid treatment to commence, and increases the likelihood of a positive outcome for the patient.

Reference list

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National Institute of Health and Clinical Excellence. (2010). Chest Pain of Recent Onset: Assessment and Diagnosis. Retrieved from: https://www.nice.org.uk/guidance/cg95

National Institute of Health and Clinical Excellence. (2013). Myocardial Infarction with ST-Segment Elevation: Acute Management: Retrieved from: https://www.nice.org.uk/guidance/cg167?unlid=688318161201611953530

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