The possible etiology of the vibratory systolic murmur

Innocent Heart Murmur

Heart murmur is the most common reason for a referral to a pediatric cardiologist. Virtually all children have a heart murmur during their childhood. Less than 1% of murmurs are pathological in children. Innocent/functional heart murmur is the most common type of heart murmur. There are multiple theories proposed to identify etiology of innocent heart murmur with varying consensus, but everybody agrees that innocent heart murmur does not carry any morbidity or mortality risk. Even today, heart murmur is associated with high physician uncertainty and parental anxiety. Extensive cardiac evaluation for such a benign finding is also associated with high health care utilization and cost. This article attempts to review this long-known finding which continues to remain a diagnostic challenge.

Epidemiology of left ventricular false tendons: clinical correlates in the Framingham Heart Study

OBJECTIVE

The study objective was to describe the echocardiographic characteristics and investigate the clinical correlates and prognostic significance of left ventricular false tendons (LVFTs). Although LVFTs are generally considered as anatomic variants, they have been associated with innocent precordial murmurs and electrocardiographic abnormalities in small case series. The correlates of LVFTs in the community are unknown.

METHODS

We compared 101 Framingham Study participants with LVFTs (mean age 56 years, 45% were women) on routine two-dimensional echocardiograms with 151 referents without LVFTs (mean age 57 years, 44% were women). We examined the cross-sectional clinical, electrocardiographic (rest and ambulatory), and echocardiographic correlates of LVFTs using logistic regression models and evaluated the prospective association between LVFTs and all-cause mortality using Cox proportional hazards regression models.

RESULTS

A total of 107 LVFTs (94 simple with 2 points of attachment and 13 complex/branching type with 3 or more points of attachment) were identified in 101 participants. LVFTs were most commonly visualized in the apical 4-chamber view (81%) and predominantly localized to the apical third of the left ventricular cavity (78%). LVFTs were associated with the presence of innocent precordial murmurs (multivariable adjusted odds ratio [OR] 5.55, 95% confidence interval [CI], 1.40-21.94) and electrocardiographic left ventricular hypertrophy (OR 4.43; 95% CI, 1.08-18.25). Body mass index was inversely related to the presence of LVFTs (per kilogram/meters squared increment; OR 0.94; 95% CI, 0.88-0.99). LVFTs were not associated with QRS axis deviation, ventricular premature beats, or repolarization abnormalities (all P values > .20). During a mean (+/- standard deviation) follow-up of 7.7 (+/-1.6) years, 15 participants with LVFTs and 19 participants without LVFTs died. In multivariable analyses, the presence of LVFTs was not associated with the risk of death (P = .92).

CONCLUSION

In our community-based sample of middle-aged to elderly white women and men, LVFTs were more likely to be identified in individuals with lower body mass index and cross-sectionally associated with the presence of innocent precordial murmurs and electrocardiographic left ventricular hypertrophy, but they were not associated with the risk of mortality.

Echocardiographic study on the origin of the innocent flow murmurs

To investigate the origin of the pulmonary systolic ejection innocent flow murmur (IFM), echocardiographic examinations were undertaken in 30 children with IFM and in a control group consisting of 28 healthy children without murmur. Compared to the controls, the diameters of the left ventricular outflow tract (LVOT) and aortic valve annulus and aortic valve area tended to be smaller, whereas stroke volume (SV) and cardiac output were slightly greater in children with IFM, but they were not statistically significant. Mean fractional shortening was significantly higher in children with IFM. Peak flow velocity of LVOT, right ventricular outflow tract, aorta, and pulmonary artery, mean velocity and velocity time integral of the aortic and pulmonary flow, and maximal acceleration of the aortic flow were all significantly higher in the IFM group compared to the controls. The variables of left-sided flow velocities in the same individuals with IFM were significantly higher compared to those derived from the right heart. The ratios of the SV to the LVOT diameter and to the aortic valve area were found to be significantly greater. It was concluded that IFM originates from higher blood flow velocities in the region of LVOT and aortic valve annulus, and that the increased flow velocity results from the larger SV passing through the relatively narrow LVOT and aortic valve in children with IFM.

Heart murmur and anaemia in the pediatric population

Innocent heart murmurs are hearth murmurs that occur in patients with a normal heart structure. They do not represent a disease of the heart and vascular system, and should not be treated as such. Iron-deficiency anaemia often causes, along with other symptoms, systolic heart murmurs and tachycardia. It appears in children of all ages representing a most common haematological paediatric disease. To establish the influence of iron-deficiency anaemia on genesis of innocent murmurs and to compare auscultatory and phono-electrocardiographic findings in patients with anaemia and heart murmurs before and after iron therapy. The study includes 120 patients with innocent heart murmurs that have been auscultated at cardio-rheumatic outpatient department of Pediatric Clinic of the Clinical Center of the University of Sarajevo, during the period from 01/01/2004 to 31/12/2004. Further diagnostic procedure, i.e. laboratory tests, diagnosed iron-deficiency anaemia in 30/120 patients. These patients have been followed in this study. 22/30 patients had systolic murmur I/II intensity of Levin scale; 8/30 patients had II/VI systolic murmurs of intensity by Levin. The highest number of examinees had 0-1 years of age, and in this group the number of boys was higher than the number of girls (M: F = 12:4). During the auscultatory and phono-ECG examinations of murmurs, 6 patients had haemoglobin values less than 95 g/l, which corresponds to an average and severe type of anaemia. 24 patients had haemoglobin values between 95 and 110 g/l, which corresponds to benign type of anaemia. The most numerous were patients aged between 0 - 1 year (3 patients with hemoglobin value Hb < 95 g/l, 13 patients with hemoglobin value Hb 95-110 g/l). All patients were treated with iron medicaments. After three months, clinical and laboratory re-evaluation was performed and it has demonstrated that after iron therapy 24 patients had level of a haemoglobin Hb >110 g/l and 6 patients had haemoglobin levels between 95 and 110 g/l. By auscultatory and phono-ECG examinations, murmurs of a level of intensity I/II was registered in only one child, while in the other 29 patients there were not any registered heart murmurs. Diagnosis of anaemia in the paediatric population group delays definitive diagnosis of heart murmurs. Innocent murmurs in children with sideropenic anaemia occur as its consequence. After adequately conducted iron therapy, i.e. cured anaemia, heart murmurs were not auscultated.

What makes a heart murmur innocent?

The physician determines that a murmur is innocent by evaluating it on its own merits. The information should be assessed in a logical and orderly fashion, and the possibilities are considered based on the information that is obtained. All of this information is processed through the physician's knowledge and experience base, and then a decision is made. One cannot increase one's skill as a cardiac auscultator by reading articles such as this-one can only learn what is abnormal by being completely comfortable with what is normal. There is no substitution for listening to many hearts, but the physician must listen to normal hearts thoughtfully and analytically. What makes a heart murmur innocent? The answer to this question includes the characteristics of the murmur in the context of the patient's total cardiovascular examination. How are these characteristics determined? They are determined the same way as any other technical skill is accomplished-with practice.

Genesis of Still's murmurs: a controlled Doppler echocardiographic study

OBJECTIVE

The origin of innocent systolic murmurs is uncertain. This study was designed to evaluate the relative contribution in the same subjects of the main factors implicated in the genesis of vibratory innocent systolic murmurs--that is, the presence of left ventricular bands and increased left ventricular flow indices--and to examine evidence for turbulence in relation to these findings.

PATIENTS

40 children with innocent systolic murmurs and 40 paired controls without murmurs were matched for age and body surface area.

DESIGN

These subjects were examined prospectively by cross sectional echocardiography with pulsed and continuous wave Doppler and colour flow mapping.

SETTING

A tertiary referral centre for paediatric cardiology.

RESULTS

Left ventricular bands were significantly more prevalent in patients with innocent murmurs (70%) than in controls (48%) but only if apical bands were included (p = 0.039). Cases had significantly higher aortic peak flow velocities (p less than 0.001), flow integrals (p = 0.001), and stroke volumes (p = 0.014), and significantly lower heart rates (p = 0.033) than controls. There were no significant differences between cases and controls in mean aortic diameter, cardiac output, or ejection fraction. There was no evidence of turbulence in the left ventricle or outflow tract in any individual but curvilinear periodic vibrations and audible "whoops" were detected in the left ventricle by pulsed wave Doppler echocardiography. These were significantly more common in cases than controls (p less than 0.01) but were not related to the presence of bands.

CONCLUSIONS

Innocent systolic murmurs were unrelated to aortic size but they were strongly associated with higher aortic flow volume and velocity, with relative bradycardia, and with evidence of vibratory phenomena in the left ventricle. The role of left ventricular bands remains uncertain.