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Hypertrophic cardiomyopathy with systolic anterior motion of the posterior mitral leaflet / Hipertrofik kardiyomiyopatide mitral kapagin arka yaprakciginin sistolik on hareketi.

A 63-year-old man with diagnosed hypertrophic cardiomyopathy (HCM) was referred for sudden death risk assessment. The diagnosis was established one year ago in another hospital, where the patient was admitted with dyspnea on exertion. When the patient came to our attention, he complained of mild exertional dyspnea (New York Heart Association functional class II), but without syncope or chest pain. There was no family history of HCM or sudden death. He had neither history of arterial hypertension nor any other systemic disease. The patient's blood pressure was 130/70 mmHg and a grade 3-4/6 systolic ejection murmur was present at the apex with radiation to the lower left parasternal border. The murmur was exaggerated during Valsalva maneuver. Electrocardiogram (ECG) showed a left bundle branch block pattern. A two-dimensional echocardiogram (Fig. 1, Video 1. See corresponding video/movie images at www.anakarder.com) revealed: an asymmetrical type of left ventricular (LV) hypertrophy with maximum wall thickness of 24 mm measured atthe anterior ventricular septum; LV end diastolic dimension of 55 mm; left atrium size of 45 mm; and LV outflow obstruction due to systolic anterior motion (SAM) of the posterior mitral leaflet (PML) (Doppler echocardiography estimated 39 mm Hg gradient at rest and 65 mmHg after Valsalva maneuver). The mitral annulus had severe calcification with elongated PML (37 mm) with mild mitral regurgitation. The patient had a normal blood pressure response on exercise test, no episodes of non-sustained ventricular tachycardia in 24-hour ECG recording, and absence of late hyperenhancement in cardiac magnetic resonance imaging. He was put on [beta]-blockers therapy and after a 3-month follow up period he remained with mild symptoms and no significant drop in LV outflow tract gradient.

[FIGURE 1 OMITTED]

Systolic anterior motion selectively of the PML with posterior leaflet-septal contact is not exceptional in generating LV outflow tract obstruction in patients with HCM being identifiable in about 10% of previously studied series of patients (1-3). It is difficult to isolate one causative factor for SAM, given the complex interplay of mechanical and flow factors contributing to it The initial mechanism proposed for the etiology of SAM was the increased flow velocity and decreased pressure above the valve caused by the hypertrophied interventricular septum, (the Venturi effect) (4). The more recently investigated mechanism concerns the decrease in effective posterior restraint (increased leaflet slack) caused by anterior redirection of papillary muscle tension; increased length of the residual leaflet, which is relatively free to move anteriorly, unlike the coapted leaflet bodies; and interposition of the leaflets into the path of outflow with the potential to cause drag forces (pushing forces of flow) (5, 6).

The present case reinforces the notion that SAM is mostly due to the drag flow phenomenon and not to the Venturi effect According to Sherrid et al. (7) Venturi flow in the outflow tract cannot be lifting the posterior leaflet because there is little or no area of this leaflet exposed to outflow tract flow and also the PML is shielded and separated from outflow tract flow by the cowl of the anterior leaflet (7). Finally, it should be emphasized that patients with obstructive HCM often have primary structural abnormalities of the mitral apparatus, including displacement of the papillary muscles anteriorly and toward one another with a concomitant anterior shift of the mitral valve, as well as elongated and slack leaflets with altered coaptation (5,7). These findings suggest that HCM is a disease not only of the muscle, but also of the mitral valve and reinforce the hypothesis that primary changes in the mitral apparatus and, in particular, papillary muscle displacement, can be a primary cause of SAM, independent of septal hypertrophy.

In conclusion, SAM selectively of the posterior mitral leaflet with posterior leaflet-septal contact is not exceptional in generating LV outflow tract obstruction in patients with HCM. Furthermore, it suggests that the drag forces are more important than Venturi effect for causing SAM.

References

(1.) Spirito P, Maron BJ. Patterns of systolic anterior motion of the mitral valve in hypertrophic cardiomyopathy: assessment by two-dimensional echocardiography. Am J Cardiol 1984; 54:1039-46.

(2.) Maron BJ, Harding AM, Spirito P, Roberts WC, Waller BF. Systolic anterior motion of the posterior mitral leaflet: a previously unrecognized cause of dynamic subaortic obstruction in patients with hypertrophic cardiomyopathy. Circulation 1983; 68: 282-93.

(3.) Moro E, ten Cate FJ, Leonard JJ, Roeland J. Prevalence of systolic anterior motion of the mural (posterior) leaflet of the mitral valve in hypertrophic cardiomyopathy: an echocardiographic study. Int J Cardiol 1987; 17: 197-205.

(4.) Spirito P, Maron BJ. Significance of left ventricular outflow tract cross-sectional area in hypertrophic cardiomyopathy: a two-dimensional echocardiographic assessment. Circulation 1983; 67: 1100-8.

(5.) Levine RA, Vlahakes GJ, Lefebvre X, Guerrero L, Cape EG, Yoganathanet AP, et al. Papillary muscle displacement causes systolic anterior motion of the mitral valve. Circulation 1995; 91: 1189-95.

(6.) Jiang L, Levine RA, King ME, Weyman AE. An integrated mechanism for systolic anterior motion of the mitral valve in hypertrophic cardiomyopathy based on echocardiographic findings. Am Heart J 1987; 113: 633-44

(7.) Sherrid MV, Gunsburg DZ, Moldenhauer S, Pearle G. Systolic anterior motion begins at low left ventricular outflow tract velocity in obstructive hypertrophic cardiomyopathy. J Am Coll Cardiol 2000; 36:1344-54.

Georgios K. Efthimiadis, Haralambos Karvounis,

Georgios Giannakoulas, Despina Parcharidou, Georgios E. Parcharidis

Cardiology Department, AHEPA Hospital,

Aristotle University, Thessaloniki, Greece

Address for Correspondence: Georgios K. Efthimiadis, MD, 30 Agias Sofias Str, 546 23, Thessaloniki, Greece Phone: +302310994830 Fax: +302310994673 E-mail: efthymos@med.auth.gr
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Title Annotation:Original Images / Orijinal Goruntuler
Author:Efthimiadis, Georgios K.; Karvounis, Haralambos; Giannakoulas, Georgios; Parcharidou, Despina; Parch
Publication:The Anatolian Journal of Cardiology (Anadolu Kardiyoloji Dergisi)
Article Type:Case study
Geographic Code:4EUGR
Date:Sep 1, 2007
Words:914
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