Musical murmur in a dog with acute chordae tendineae rupture

Abstract

Abstract : A 6 year-old, spayed female, Maltese dog was presented with precordial thrill and mild coughing. Thoracicauscultation revealed a grade V/VI systolic murmur with maximal intensity over the left apex characterized by musicalmurmur. Echocardiography revealed mild myxomatous degeneration of mitral valve and ruptured chordae tendineae.Musical murmur was produced due to the vibration of ruptured piece of chordae tendineae along with regurgitant flow.After treatment with furosemide and ramipril, clinical signs resolved and precordial thrill reduced. This case reportdescribes typical clinical signs and phonocardiogram of musical murmur in a dog with acute chordae tendineae rupture.Keywords : chordae tendineae rupture, mitral valve disease, musical murmur Mitral valve disease (MVD) is the most common acquiredheart disease in small breed-dogs and characterized by myx-omatous valvular degeneration [3, 5, 6, 7, 8]. It results inmitral valve insufficiency creating systolic mitral regurgita-tion, which in turn leads to a left apical systolic murmur [7].Usually with MVD, systolic murmur intensity is related to dis-ease severity. However, occasionally with mild stage of MVD,the murmur has a musical quality and striking intensity [9].This case describes sudden onset of precordial thrill char-acterized as musical murmur resulted from acutely rupturedchordae tendineae with midly degenerated mitral valve.A 6 year-old, spayed female, Maltese dog was presentedwith sudden onset of precordial thrill and mild nocturnalcoughing. Thoracic auscultation revealed a grade V/VI sys-tolic murmur with maximal intensity over the left apex. Lab-oratory data including a complete blood count, serumbiochemical analysis were within normal ranges. Evaluationof the electrocardiogram showed mildly prolonged P wave.Thoracic radiography revealed bronchointerstitial pattern inbilateral caudal lung lobes. 2D-echocardiography demon-strated slightly thickened mitral valve and pieces of rupturedchordae tendineae attached to the tip of mitral valve leaflet(Fig. 1). Doppler echocardiography revealed mild systolicturbulent flow in the left atrium running around atrial wallwith peak velocity 2.07 m/sec and pressure gradient 17.2mmHg (Fig. 1). There was no marked evidence of cardiacremodeling. Phonocardiography was performed, and showedmid-systolic diamond shape murmur with variable ampli-tudes (Fig. 2). Recorded sound files of phonocardiogramrevealed sharp, pitched ‘wheeping’ sound, characterized asmusical murmur. The blood sample collected aseptically wassubmitted for aerobic and anaerobic blood culture, and theresult was negative. Based on the physical and clinical exam-ination, the dog was diagnosed as mitral valve degeneration(MVD) with chordae tendineae rupture (CTR). Furosemide(Lasix, 0.5 mg/kg, oral, twice daily; Handok phrmaceuticals,Korea) and ramipril (Vasotop, 0.125 mg/kg, oral, once adaily; Intervet, Korea) were administered. After 1 month ofmedical treatment, nocturnal coughing was improved andprecordial thrill was reduced.Generally, musical murmur is characterized by a strikingmusical quality and is frequently so loud that it can be heardover the entire thorax. The murmur has been described inhuman literature using following terms: “cooing of a dove,”,“buzzing of a saw”, “like a cuckoo clock,” “like the spinningof a top” [1]. Musical murmur would occur owing to the res-onance of vibrating structure projecting into the regurgitantblood flow. In human medicine, musical murmur is most fre-quently occurred in aortic stenosis [4]. In the present case, itwas ruptured piece of chordae tendineae flailed with mitralvalve during systole vibrating with turbulent blood flow thatmade loud, pinched sound. The size of turbulent jet flow wasrelatively small and ran around the atrial wall. The directionof jet flow indicated that the degeneration of anterior leafletwas worse than posterior leaflet.Historically, CTR is commonly described as a devastatingcomplication of MVD, because it is responsible for acute leftheart failure leading to pulmonary edema and death [2, 8].However, one study suggested that 24.6% of the dogs withCTR were asymptomatic and therefore assigned to Interna-tional Small Animal Health Council (ISACHC) classes Iaand Ib at the time of diagnosis [8]. In this case, 2-D echocar-