What Is Still’s Murmur?

Introduction 

A Still’s murmur is a low-pitched, musical sound created by blood flowing through your heart. It is a benign murmur, that is not associated with any cardiac disorder.¹ 

This is mostly common in children aged 3 to 6 and will usually go away before they become adults.² 

Understanding heart murmurs 

Definition of heart murmurs 

A heart murmur is a blowing, whooshing sound that can be heard during a heartbeat, which is caused by a rough blood flow through the heart valves. 

Types of heart murmurs 

Innocent or benign murmurs 

An innocent or benign murmur is not associated with any disease but makes an unusual sound due to the travelling of the blood in the heart.^3,4 

Cervical venous hum 

Cervical venous hum is a common type of innocent heart murmur that is caused by the sound of blood flow returning normally through the veins above the heart. However, sometimes a slight angle can be produced causing a slightly turbulent blood flow. 

Pulmonary flow murmur 

A pulmonary flow murmur causes the sound of normal blood flow across the pulmonary valve. The blood flow in this type of murmur is normal but may produce extra sounds. This can develop at any age but is common in older children and teenagers, this may be more likely in those who have a thin chest wall as the pulmonary valve is close to the chest wall. 

Supraclavicular systemic flow murmur 

A Supraclavicular systemic flow murmur is a harsh, high-pitched murmur caused by normal blood flow into the aorta. 

Pathologic murmurs 

A pathologic murmur is a murmur caused by heart disease. This occurs when the blood travels through a leaky or narrowed heart valve. The heart conditions associated with this type of murmur, such as structural heart disease, may cause symptoms such as shortness of breath.⁵ 

Characteristics of Still's murmur 

Occurrence in healthy children 

The occurrence of Still’s murmur in healthy children is not a cause of concern. This is because it does not correlate to any heart disorders and children can continue with everyday tasks such as playing sports without being affected. 

Timing in the cardiac cycle 

A cardiac cycle is marked by the S1 systole and S2 diastole sounds. A still murmur signal has a diamond-shaped envelope of pure low frequency that occurs shortly after the S1⁶, this feature makes it easier to classify a Still’s murmur. 

Location of auscultation 

Auscultation is the action of listening to sounds from the heart using a stethoscope. In Still’s murmur, the location of auscultation will be heard at the left lower sternal border and does not radiate.⁷ 

Quality and intensity 

The quality and intensity of a Still’s murmur is a brief vibratory quality that is grade I-III, which is a faint, soft or easily audible sound. 

Changes with patient's age 

This is mostly common in children aged 3 to 6 and will usually go away before they are adults. 

Causes and mechanism 

Turbulence of blood flow 

Blood flow through the heart causes the sounds of a Still's murmur. However, the exact cause remains unclear. A possible reason is that fibrous bands in the left ventricle may produce a vibrating noise with blood flow. There is also a possible link that the increased turbulence of blood flow through the heart may be linked to anaemia. This study found that iron therapy to treat the anaemia showed that heart murmurs were not auscultated.⁸ 

Hemodynamic factors 

Hemodynamic factors are things that affect how well your blood flows, this can make it easier or harder for blood to reach the tissues and organs. One study focused on the hemodynamic interaction between the left ventricle and the aorta and applied the model of ventriculo-arterial coupling (VAC), this model describes the heart based on the pressure-volume relation, they found that children with Still's murmur had a lower VAC ratio than those without.⁹ 

Differences between Still's Murmur and pathologic murmurs 

There are many features that can differentiate a Still's murmur and pathologic murmurs. This includes the intensity, as Still's murmurs are quieter and less intense and Still's murmurs will not be related to other cardiovascular symptoms such as chest pain, shortness of breath and sweating with minimal activity. 

Diagnosis 

Medical history and physical examination 

Considering a child's medical history can be useful in the diagnosis of a Still's murmur. In infants, this will often be done by looking at the mother's history as maternal age is associated with an increased risk of heart defects. In children, a patient's activity level and exercise levels should be monitored as shortness of breath due to this may be linked to a murmur. 

Physical examination will often start with a general checkup, followed by examining vital signs such as blood pressure, oxygen and palpitation of the chest. 

If the doctor hears a heart murmur, they will monitor changes with movement, as lying down causes the Stills’ murmur to sound louder. They may also monitor if the murmur occurs when the heart is resting or contracting. 

Auscultation with a stethoscope 

Auscultation is the primary method of diagnosis for Still’s murmur. The doctor will use a stethoscope to look at the 4 chambers of the heart – aortic, pulmonary, tricuspid and mitral followed by the neck and back. The doctor will be looking for any abnormalities or extra sounds for the presence of a murmur. 

Echocardiography 

An echocardiogram is a type of ultrasound test used to check the structure and function of the heart. In the case of Still’s murmur, they may be used to clarify the diagnosis from auscultation.⁹

Distinguishing Still's Murmur from other murmurs 

A Still's murmur can be distinguished from other murmurs because it has a soft sound and a lack of extra clicks in the heart sounds. A Still's murmur should only be heard in one place as it has no radiation to other places, this often occurs in the lower left area. 

Prognosis and Management 

Reassurance for parents and caregivers 

A diagnosis of Still's murmur often causes anxiety in parents. Therefore, it is important to reassure the parents that the child does not need to make any specific lifestyle changes such as a change of diet or reduced activity. The parent should also understand that most children with Still’s murmur will only have this for a short period of time, as the murmur will go away as the child gets older. 

Monitoring and follow-up 

Although Still's murmur is a condition that does not require any lifestyle changes or treatment. It is recommended to see a healthcare provider for physical examinations to monitor a child’s health. If a child displays any new symptoms such as chest pain or difficulties in breathing a doctor should conduct any examinations.

Indications for referral to a paediatric cardiologist 

In the case that an infant is less than 3 months of age and presents with a murmur that is associated with shortness of breath, and sweating when feeding, should be referred to a paediatric cardiologist. 

Long-term outcomes and potential complications 

A Still's murmur is a short-term health problem that will usually go away as the child gets older. There is no need for long-term treatment and there are no potential complications as this does not lead to other health conditions as there is nothing physically wrong with the heart. 

Summary

Recap of key points 

A heart murmur is a blowing, whooshing sound that can be heard during a heartbeat, which is caused by a rough blood flow through the heart valves. There are different types of heart murmurs – innocent or pathologic. A Still's murmur is a type of innocent heart murmur, commonly diagnosed in young children, that causes a quiet sound, this will usually pass as the child grows older. 

It is important to evaluate any problems with the heart correctly and to give an accurate diagnosis, although a Still's murmur is not a very serious condition, other heart problems may cause long-term issues and complications for a patient.

It is also important that the healthcare provider ensures that the parent of a young patient has all the information they need on this disease so that the patient and parents have no feelings of anxiety and worry, as they will be able to understand that a Still's murmur will not affect their daily activities and does not need any long term treatment.