European Heart Journal Advance Access originally published online on September 13, 2007
European Heart Journal 2007 28(20):2554; doi:10.1093/eurheartj/ehm359
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Effect of dynamic myocardial dyssynchrony on mitral regurgitation during supine bicycle exercise stress echocardiography in patients with idiopathic dilated cardiomyopathy and 'narrow' QRS.
Department of Ultrasound
The First Affiliated Hospital
College of Medicine
Zhejiang University
#79 Qingchun Road
Hangzhou
Zhejiang 3100003
People's Republic of China
Tel: +86 571 8723 6628 Fax: +86 571 8723 6628 E-mail address: zezhou_song{at}126.com
I read with great interest the study by D'Andrea et al., 1 which confirmed that the increase in left ventricular (LV) dyssynchrony during exercise strongly correlates with the increase in mitral regurgitation (MR) severity and with the impairment of LV stroke volume. The methods and interpretation of the results, however, raise several concerns.
Abnormal interventricular activation and mechanical asynchrony may result in dynamic changes throughout the cardiac cycle in both pressure and volume between the ventricles. These differences in transseptal pressure or volume may be reflected via the septum and cause septal displacement. As a result, the onset of contraction in the right ventricle (RV) occurred before the LV, increased pressure during RV isovolumic systole presumably exceeded LV end-diastolic pressure and the septum was displaced into the LV2 which may increase diastolic MR and decrease LV stroke volume. In this study, D'Andrea et al.1 stated that a significant interventricular electromechanical delay was detected and the results were given in Table 2. However, the relation of interventricular electromechanical delay to the increase in MR severity during exercise was not well described. Did the increase in interventricular electromechanical delay correlate with the increase in MR severity and with the impairment of LV stroke volume?
As a result of the development of a LV-left atrial reverse pressure gradient when atrial contraction is not followed by an appropriately timed ventricular systole, diastolic MR is more likely with the incomplete mitral valve closure.3 Breithardt et al.4 proposed that CRT can restore the mechanical atrioventricular (AV) synchrony and increase LV contraction efficiency, thereby generating the effective transmitral closing force and reducing MR. In this study, however, D'Andrea et al.1 stated that the condition of AV synchrony was not well described. Was a significant AV electromechanical delay detected during exercise? Were there any relations of AV electromechanical delay during exercise to the increase in MR severity and with the impairment of LV stroke volume? The above-mentioned questions need to be further studied.
References
- D'Andrea A, Caso P, Cuomo S, Scarafile R, Salerno G, Limongelli G, Salvo GD, Severino S, Ascione L, Calabro P, Romano M, Romano G, Santangelo L, Maiello C, Cotrufo M, Calabro R. Effect of dynamic myocardial dyssynchrony on mitral regurgitation during supine bicycle exercise stress echocardiography in patients with idiopathic dilated cardiomyopathy and ‘narrow’ QRS. Eur Heart J (2007) 28:1004–1011.
[Abstract/Free Full Text] - Grines CL, Bashore TM, Boudoulas H, Olson S, Shafer P, Wooley CF. Functional abnormalities in isolated left bundle branch block: the effect of interventricular asynchrony. Circulation (1989) 79:845–853.
[Abstract/Free Full Text] - Appleton CP, Basnight MA, Gonzalez MS. Diastolic mitral regurgitation with atrioventricular conduction abnormalities: relation of mitral flow velocity to transmitral pressure gradients in conscious dogs. J Am Coll Cardiol (1991) 18:843–849.[Abstract]
- Breithardt OA, Sinha AM, Schwammenthal E, Bidaoui N, Markus KU, Franke A, Stellbrink C. Acute effects of cardiac resynchronization therapy on functional mitral regurgitation in advanced systolic heart failure. J Am Coll Cardiol (2003) 41:765–770.
[Abstract/Free Full Text]
CiteULike 
Connotea 
Del.icio.us What's this?
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||