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Rao. Vessel Plus 2022;6:22 https://dx.doi.org/10.20517/2574-1209.2021.105 Page 17 of 24

Table 7. Etiology of mid-diastolic murmurs. Modified from Rao [5]

1. Large flow across the mitral valve
(a) Ventricular septal defect
(b) Patent ductus arteriosus
(c) Mitral regurgitation
2. Rheumatic mitral valvulitis (Carey Coombs murmur)
3. Aortic regurgitation (Austin Flint murmur)
4. Mitral stenosis
5. Large flow across the tricuspid valve
(a) Atrial septal defect
(b) Anomalous pulmonary venous connection (partial or total)
(c) Tricuspid regurgitation
6. Tricuspid stenosis

heart defects such as VSD or PDA or due to moderate to severe MR (Table 7; Item 1). A holosystolic, non-
radiating murmur of VSD auscultated at the lower left sternal border, a continuous murmur of PDA heard
at the LUSB, or holosystolic murmur of MR auscultated at the apical region with radiation to anterior, and
mid axillary lines will help differentiate them from one another.

Rheumatic mitral valvulitis
In patients with acute rheumatic fever, a mid-diastolic murmur at the apex, named Carey Coombs murmur
may be auscultated. While the etiology of this murmur is not clearly established, it is generally thought that
this murmur is related to the thickening of the mitral valve leaflets along with edema. Another hypothesis is
that there is relative stenosis of the mitral valve produced by a dilated LV. In patients with clinically
suspected rheumatic fever diagnosis, appreciation of Carey Coombs murmur is indicative of involvement of
the mitral valve in the rheumatic disease process.

Austin flint murmur of aortic regurgitation
In subjects with AR, a mid-diastolic rumble at the apex, named Austin Flint murmur may be heard at the
apex. This murmur is believed to result from the jet of the AR impinging on the anterior leaflet of the mitral
valve, making it shudder. The presence of a high-pitched early diastolic murmur of AR at RUSB implies that
this apical murmur is an Austin Flint type of murmur.

Mitral stenosis
Rheumatic and congenital mitral stenoses do result in mid-diastolic murmurs; however, typically, the mid-
diastolic murmur spills into the later part of the diastole and becomes more prominent and is termed
presystolic accentuation.

Increased flow across the tricuspid valve
Increased flow across the tricuspid valve is produced by (1) large shunts caused by ASD, PAPVC, or total
anomalous pulmonary venous connection (TAPVC); and (2) moderate to severe TR (Table 7; Item 5). All
types of ASDs (secundum, primum, sinus venosus, and coronary sinus), if they are large enough to result in
Qp:Qs ratio ≥ 2:1, may have a mid-diastolic murmur auscultated best at the LLSB. Unfortunately, there are
no characteristic findings of the mid-diastolic murmur that differentiates one from the other. Clinical signs
of ASD, PAPVC, or TAPVC or of the murmur of TR heard best at the LLSB are useful in differentiating the
etiology of mid-diastolic flow murmurs heard best at the LLSB.