68 / 78
CARDIOVASCULAR JOURNAL OF AFRICA • Volume 26, No 4, July/August 2015
e14
AFRICA
asynchrony related to functional mitral regurgitation.
6,7
Functional mitral regurgitation in patients with left bundle
block has multiple components, including asynchrony of the
papillary muscles due to delay in ventricular conduction, which
causes a delay in the contraction of the papillary muscles.
8,9
The
delayed movement of certain areas of the left ventricle (lateral
wall or interventricular septum) leads to a reduction in the force
of mitral valve closure due to the fall in systolic volume caused
by the asynchronous mechanical contraction.
Long-term right ventricular (RV) apical pacing can also
cause MR. It has been shown in canine models that RV pacing
can increase mitral and tricuspid valve incompetence.
10
While
the incidence of MR appeared to be low at baseline, this
study showed that MR can increase in the course of time due
to permanent RV apical pacing. This holds true, especially in
patients with pre-existing MR.
Left ventricular dyssynchrony can be considered as a cause
of MR after long-term RV apical pacing. There are a few
reported cases of acute severe MR as an immediate peri-
operative complication of pacemaker insertion, leading to
acute haemodynamic deterioration. Rita
et al.
demonstrated
that RVA pacing may immediately induce severe MR and acute
cardiac failure, even in patients with preserved LV contraction.
11
This case also shows RV outflow tract pacing improves MR
compared with apical pacing, probably by improving ventricular
dyssynchrony.
Diastolic mitral regurgitation (DMR) is a common
phenomenon seen in patients with AV blocks, hypertrophic
cardiomyopathy, advanced left ventricular systolic dysfunction,
aortic valve disease, and in the presence of atrial fibrillation with
long cardiac cycles. The haemodynamic mechanism leading to
DMR is due to a positive ventricular-to-atrial (V–A) pressure
gradient occurring during diastole.
12,13
Because of the AV
dyssynchrony, the AV pressure gradient reverses (ventricular
pressure becomes higher than atrial), resulting in DMR in the
presence of an incompletely closed mitral valve.
14
Conclusion
These two cases illustrate different mechanisms of mitral
regurgitation, which may have different haemodynamic
consequences and clinical implications. The cases underline
the importance of a high index of suspicion in patients
with intermittent heart failure, and a careful analysis of
echocardiographic images with simultaneous ECG, in order to
delineate systolic and diastolic MR.
References
1.
Enriquez-Sarano M, Akins CW, Vahanian A. Mitral regurgitation.
Lancet
2009;
373
: 1382–9134.
2.
Agricola E, Oppizzi M, Galderisi M,
et al
. Role of regional mechani-
cal dyssynchrony as a determinant of functional mitral regurgitation
in patients with left ventricular systolic dysfunction.
Heart
2006;
92
:1390–1395.
3.
Finelli D, Mehta J. Transient severe mitral regurgitation due to myocar-
dial ischemia.
Chest
1982;
82
: 376–378.
4.
Otsuji Y, Gilon D, Jiang L,
et al
. Restricted diastolic opening of the
mitral leaflets in patients with left ventricular dysfunction: evidence for
increased valve tethering.
J Am Coll Cardiol
1998;
32
: 398–340.
5.
Avierinos JF, Thuny F, Tafanelli L,
et al
. Eclipsed mitral regurgitation:
a new form of functional mitral regurgitation for an unusual cause of
heart failure with normal ejection fraction.
Cardiology
2008;
110
(1):
29–34.
6.
Leclercq C, Kass DA. Retiming the failing heart: principles and current
clinical status of cardiac resynchronization.
J Am Coll Cardiol
2002;
39
: 194–201.
7.
Ypenburg C, Lancellotti P, Tops LF,
et al
. Acute effects of initiation and
withdrawal of cardiac resynchronization therapy on papillary muscle
dyssynchrony and mitral regurgitation.
J Am Coll Cardiol
2007;
50
:
2071–2077.
8.
Breithardt OA, Sinha AM, Schwammenthal E,
et al
. Acute effects of
cardiac resynchronization therapy on functional mitral regurgitation in
advanced systolic heart failure
. J Am Coll Cardiol
2003;
41
: 765–770.
9.
Alessandri N, Mariani S, Messina FR,
et al.
Diastolic mitral regurgi-
tation: A borderline case in cardiovascular physiology.
Eur Rev Med
Pharmacol Sci
2003;
7
: 161–170.
10. Maurer G, Torres MA, Corday E,
et al
. Two-dimentional echocar-
diographic contrast assessment of pacing-induced mitral regurgitation:
relation to altered regional left ventricular function.
J Am Coll Cardiol
1984;
3
: 986–991.
11. Rita M, Sofia A, Luis B,
et al
. Acute severe mitral regurgitation as
an early complication of pacemaker implantation.
Europace
2010;
12
:
1791–1792.
12. Raffa S, Zito C, Oliva S,
et al
. Diastolic mitral and tricuspid regurgita-
tion.
Ecocardiography
2006;
23
: 251–253.
13. Schnittger I, Appleton CP, Hatle LK,
et al
. Diastolic mitral and tricus-
pid regurgitation by Doppler echocardiography in patients with atrio-
ventricular block: New insight into the mechanism of atrioventricular
valve closure.
J Am Coll Cardiol
1988;
11
: 83–88.
14. Panidis IP, Ross J, Munley B,
et al
. Diastolic mitral regurgitation in
patients with atrioventricular conduction abnormalities: A common
finding by Doppler echocardiography.
J Am Coll Cardiol
1986;
7
:
768–774.