Heart murmur
This article may be too technical for most readers to understand.(April 2014) |
Heart murmur | |
---|---|
Insufficiency, regurgitation, stenosis |
Heart murmurs are unique
There are two types of murmur. A
Most murmurs are normal variants that can present at various ages which relate to changes of the body with age such as chest size, blood pressure, and pliability or rigidity of structures.[4]
Heart murmurs are frequently categorized by timing. These include systolic heart murmurs, diastolic heart murmurs, or continuous murmurs. These differ in the part of the heartbeat they make sound, during systole, or diastole. Yet, continuous murmurs create sound throughout both parts of the heartbeat. Continuous murmurs are not placed into the categories of diastolic or systolic murmurs.[7]
Diagnostic approach and diagnosis
Classification
Murmurs have seven main characteristics. These include timing, shape, location, radiation, intensity, pitch and quality.[8]
- Timing refers to whether the murmur is a systolic, diastolic, or continuousmurmur.
- Shape refers to the intensity over time. Murmurs can be crescendo, decrescendo or crescendo-decrescendo. Crescendo murmurs increase in intensity over time. Decrescendo murmurs decrease in intensity over time. Crescendo-decrescendo murmurs have both shapes over time. These have progressive increase in intensity, peak, and progressive decrease in intensity. Crescendo–decrescendo murmurs resemble a diamond or kite shape.
- Location refers to where the heart murmur is usually heard best. There are four places on the anterior chest wall to listen for heart murmurs. Each location roughly corresponds to a specific part of the heart.[4] Health care providers listen to these areas with a stethoscope.
Region | Location | Heart Valve Association |
---|---|---|
Aortic | 2nd right intercostal space | Aortic valve |
Pulmonic | 2nd left intercostal spaces | Pulmonic valve |
Tricuspid | 4th left intercostal space | Tricuspid valve |
Mitral | 5th left mid-clavicular intercostal space | Mitral valve |
- Position for auscultation: The patient is most often lying on their back (supine) with the head of bed at slight upward angle. The head of the bed is usually at a 30 degree upward angle. Usually the health care provider is standing to the right of the person they are examining.[4] Below are positional changes that one may use:
- Left lateral point of maximal impulse. Also, this will help to hear extra heart sounds (S3 or S4).[4]
- With the patient sitting upright.
- With the patient seated, leaning forward and holding breath after exhalation. This will decrease the distance of the chest wall to the left ventricular outflow tract. By doing so this will help find the presence of an aortic regurgitation murmur.[4]
- Left lateral
- Radiation refers to where the sound of the murmur travels. The rule of thumb is that the sound radiates in the direction of the blood flow.
- Intensity refers to the loudness of the murmur with grades according to the Levine scale, from 1 to 6:[9][10]
Levine scale | Murmur Description |
---|---|
1 | Only audible on listening carefully for some time |
2 | Faint but immediately audible on placing the stethoscope on the chest |
3 | Loud, readily audible but with no palpable thrill.[11] |
4 | loud with a palpable thrill |
5 | loud with a palpable thrill. So loud that it is audible with only the rim of the stethoscope touching the chest. |
6 | loud with a palpable thrill. Audible with the stethoscope not touching the chest but lifted just off it. |
- Pitch may be low, medium or high. This depends on whether auscultation is best with the bell or diaphragm of a stethoscope.
- Quality refers to unusual characteristics of a murmur. For example, blowing, harsh, rumbling or musical.
Interventions that change murmur sounds
- Abrupt standing
- Squatting, by increasing systemic vascular resistance. An increase in systemic vascular resistance results in an increase in afterload. With HOCM, an increase in afterload will hold the obstruction in a more open configuration. This will decrease the loudness of the murmur with HOCM.
- Handgrip maneuver, by increasing afterload. Like squatting, this will decrease the loudness of the HOCM murmur.
- Post ectopic potentiation
- Inhaled amyl nitrite. This is a vasodilator that diminishes systolic murmurs in left-to-right shunts in ventricular septal defects. It also reveals right-to left shunts in the setting of pulmonic stenosis and a ventricular septal defect.[16]
- Methoxamine
- Positioning of the patient. In the lateral decubitus position or lying on the left side. This will make murmurs in the mitral valve area more pronounced.
Anatomic sources
Systolic
Pulmonary valve stenosis is a crescendo-decrescendo systolic murmur. One can hear it best at the left upper sternal border. It has association with a systolic ejection click that increases with inspiration. This finding results from an increased venous return to the right side of the heart. Pulmonary stenosis sometimes radiates to the left clavicle.
Atrial septal defect will present with a systolic crescendo-decrescendo murmur. It is best heard at the left upper sternal border. This is the result of an increased volume going through the pulmonary valve. It has association with a fixed, split S2 and a right ventricular heave.
Ventricular septal defect (VSD) will present as a holosystolic murmur. One can hear it at the left lower sternal border. It has association with a palpable thrill, and increases with isometric handgrip. A right to left shunt (Eisenmenger syndrome) may develop with uncorrected VSDs. This is due to worsening pulmonary hypertension. Pulmonary hypertension will increase the murmur intensity and may present with cyanosis.
Flow murmur presents at the right upper sternal border. It may present in certain conditions, such as anemia, hyperthyroidism, fever, and pregnancy.
Diastolic
Mitral stenosis presents as a diastolic low-pitched decrescendo murmur. It is best heard at the cardiac apex in the left lateral decubitus position. Mitral stenosis may have an opening snap. Increasing severity will shorten the time between S2 (A2) and the opening snap. For example, in severe MS the opening snap will occur earlier after A2.
The cooing dove murmur is a cardiac murmur with a musical quality (high pitched). Associated with aortic valve regurgitation (or mitral regurgitation before rupture of chordae). It is a diastolic murmur heard over the mid-precordium.[17]
Continuous and Combined Systolic/Diastolic
Patent ductus arteriosus may present as a continuous murmur radiating to the back.
Severe coarctation of the aorta can present with a continuous murmur. One may hear the systolic component at the left infraclavicular region and the back. This is due to the stenosis. One may hear the diastolic component over the chest wall. This is due to blood flow through collateral vessels.
Ruptured aortic sinus (sinus of Valsalva) may present as a continuous murmur. This is an uncommon cause of continuous murmur[20] One may hear it at the aortic area and along the left sternal border.
Types and disease associations
- Continuous machinery murmur, at the left upper sternal border
- Classic for a patent ductus arteriosus (PDA). Signs of infants associated with serious cases of PDA are poor feeding, failure to thrive and respiratory distress. Other examination findings may include widened pulse pressures and bounding pulses. A machinery murmur is also known as a Gibson murmur.[21]
- Systolic murmur loudest below the left scapula
- Classic for a coarctation of the aorta. Coarctation of the aorta is narrowing of the aorta. This can occur in Turner's Syndromeis an X-linked disorder with absence of one X-chromosome. Other exam findings of coarctation of the aorta include radio-femoral delay. This is when the femoral pulse is later than the radial pulse. The pulses in the lower extremity may be weaker than those of the upper extremity. Another exam finding is of varying blood pressure in the upper and lower extremities. This presents as higher blood pressure in the arms and lower blood pressure in the legs.
- Harsh holosystolic (pansystolic) murmur at the left lower sternal border
- Classic for a ventricular septal defect (VSD). This may lead to the development of the delayed-onset cyanotic heart disease known as Eisenmenger syndrome. Eisenmenger syndrome is a reversal of the left-to-right heart shunt. This is the result of hypertrophy of the right ventricle over time. This causes a right-to-left heart shunt. The VSD allows deoxygenated blood to flow from the right to left side of the heart. This blood bypasses the lungs. The lack of oxygenation in the pulmonary circulation results in cyanosis.
- Widely split fixed S2 and systolic ejection murmur at the left upper sternal border
- Classic for a patent foramen ovale (PFO) or atrial septal defect (ASD). A PFO is lack of closure of the foramen ovale. At first, this produces a left-to-right heart shunt. This does not produce cyanosis, but causes pulmonary hypertension. Longstanding uncorrected atrial septal defects can also result in Eisenmenger syndrome. Eisenmenger syndromecan result in cyanosis.
Management
A medical provider (e.g. doctor) may order tests for further evaluation of a heart murmur. The
The need for treatment depends on the diagnosis and severity.[1] In some cases, the condition causing the heart murmur may prompt monitoring. Sometimes, heart murmurs disappear on their own. This happens when the cause of the heart murmur is no longer present. Monitoring will help determine how the condition changes.[1] It may stay the same, worsen, or improve. In other cases, the condition causing the heart murmur may not prompt any further tests.
Treatment ranges from medication to surgeries.
References
- ^ a b c d e f "Patient education: Heart murmurs (The Basics)". UpToDate. 25 March 2022. Retrieved 25 March 2022.
- ^ OCLC 1030994993.)
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: CS1 maint: location missing publisher (link) CS1 maint: others (link - )
- ^ OCLC 1153338113.)
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: CS1 maint: location missing publisher (link - ^ "Cardiac thrill". nih.gov. Retrieved 8 June 2022.
- ^ "heart murmur" at Dorland's Medical Dictionary
- ^ "continuous murmur" at Dorland's Medical Dictionary
- ^ "Heart murmur: characteristics". LifeHugger. Archived from the original on 24 November 2010. Retrieved 23 September 2009.
- ISBN 978-1-60547-411-3.
- .
- ^ "Medline Plus Medical Dictionary, definition of "cardiac thrill"". Archived from the original on 27 May 2011.
- ^ PMID 2897627.
- PMID 6497192.
- ^ Harrison's Internal Medicine 17th, chapter 5, "Disorders of the cardiovascular system," question 32, self assessment and board review
- ^ Harrison's Internal Medicine 17th, chapter 5, "Disorders of the cardiovascular system," question 86-87, self assessment and board review
- PMID 14047161.
- PMID 7321208. Retrieved 17 November 2022.
- PMID 9851968.
- ^ "Blaufuss Multimedia - Heart Sounds and Cardiac Arrhythmias". Medical Multimedia Laboratories. Archived from the original on 29 August 2007. Retrieved 2 August 2013.
- PMID 23620707.
- ^ "Gibson murmur". The free dictionary.com. Retrieved 27 January 2016.