Download Right Ventricular Pacing for Right Ventricular Outflow Tract Obstruction

Images in
Cardiovascular
Medicine
Right Ventricular Pacing
for Right Ventricular
Outflow Tract Obstruction
in a Man with Biventricular Hypertrophic Cardiomyopathy
Sarah E. Nelson, MD
Gautam R. Shroff, MBBS
Ronald A. Johannsen, MD
Rehan M. Karim, MBBS
A
40-year-old man with known hypertrophic cardiomyopathy presented with
syncope after coughing. Physical examination revealed a systolic murmur
that was accentuated by the Valsalva maneuver. An electrocardiogram suggested biventricular hypertrophy and biatrial enlargement (Fig. 1). Echocardiograms
revealed asymmetric septal hypertrophy with a diastolic septal thickness of 2.3 cm,
and evidence of flow acceleration across the right ventricular outflow tract (RVOT)
and left ventricular outflow tract (LVOT) (Figs. 2 and 3).
Cardiac magnetic resonance images confirmed noncontiguous hypertrophy involving the basal septal, basal anterior, and apical walls of the left ventricle, as well as the
inferior and free walls of the right ventricle (RV). A prominent muscle band in the
RVOT contributed to dynamic obstruction across the RVOT (Figs. 4 and 5). Patchy
hyperenhancement in the septum, visible in delayed-enhancement sequences after
Fig. 1 Electrocardiogram
shows evidence of biventricular hypertrophy and biatrial
enlargement.
Section Editor:
Raymond F. Stainback, MD,
Department of Adult
Cardiology, Texas Heart
Institute at St. Luke’s
Episcopal Hospital, 6624
Fannin St., Suite 2480,
Houston, TX 77030
From: Department of Internal Medicine (Dr. Nelson)
and Division of Cardiology
(Drs. Johannsen, Karim, and
Shroff), Hennepin County
Medical Center, Minneapolis, Minnesota 55415
Address for reprints:
Sarah E. Nelson, MD,
Department of Internal
Medicine, Hennepin
County Medical Center,
701 Park Ave., Minneapolis,
MN 55415
E-mail: [email protected]
Fig. 2 Transthoracic echocardiogram (parasternal long-axis view) shows systolic flow acceleration across the right (RVOT) and left ventricular
outflow tracts (LVOT).
Fig. 3 Transthoracic echocardiogram (parasternal long-axis view) shows systolic flow acceleration across the right ventricular outflow tract
(RVOT).
Click here for real-time motion image: Fig. 2.
Click here for real-time motion image: Fig. 3.
© 2013 by the Texas Heart ®
Institute, Houston
Texas Heart Institute Journal
Right Ventricular Pacing in Biventricular Hypertrophic Cardiomyopathy
367
gadolinium administration, was consistent with myocardial fibrosis (Fig. 6). The subendocardium was not
involved, suggesting a cause other than coronary disease.
Angiography was performed to measure and characterize the gradient across the RVOT. There was a hemodynamically significant gradient of 54 mmHg (mean,
33 mmHg). When the patient coughed and then performed the Valsalva maneuver, the peak gradients increased to 94 mmHg and 106 mmHg, respectively.
Potentiation of the peak gradient across the RVOT was
observed after a premature ventricular contraction (Fig.
7). Because of the patient’s unexplained syncope, a carFig. 6 Cardiac magnetic resonance image shows delayed
enhancement in the interventricular septum after gadolinium
administration (arrow), consistent with myocardial fibrosis that
spares the subendocardium.
Fig. 4 Cardiac magnetic resonance image shows noncontiguous left ventricular hypertrophy involving the basal septum and
apex (arrows).
Fig. 7 Hemodynamic tracings from right-sided heart catheter­
ization show simultaneous right ventricular (RV) pressure (across
the RV outflow tract) and pulmonary artery (PA) tracings. This
figure shows potentiation of the peak RV gradient (bottom
tracing) after a premature ventricular contraction.
dioverter-defibrillator was implanted for the primary prevention of sudden cardiac death. An atrial lead
was also implanted to accommodate any future need
for atrioventricular synchronous pacing. Transthoracic
echocardiography was performed to evaluate the effect
of RV pacing on the RVOT gradient. The peak gradient across the RVOT was 17 mmHg with RV pacing
and 37 mmHg without RV pacing (Fig. 8).
Comment
Fig. 5 Cardiac magnetic resonance image shows a hypertrophied muscle band in the right ventricular outflow tract contributing to dynamic obstruction indicated by flow acceleration (arrow).
368
Right ventricular involvement has been reported in hypertrophic cardiomyopathy; however, its prevalence is
variably described.1 Dual-chamber pacing has produced
favorable hemodynamic effects in patients with symp-
Right Ventricular Pacing in Biventricular Hypertrophic Cardiomyopathy
Volume 40, Number 3, 2013
A
tomatic LVOT obstruction.2 In comparison, RV pacing
reduced the gradient across our patient’s RVOT.
B
Acknowledgment
We thank Dr. Richard Asinger for his help with hemodynamic evaluation and critical review of the manuscript.
References
Fig. 8 Transthoracic echocardiograms show gradients across
the right ventricular outflow tract. A) With pacing, the peak gradient was 17 mmHg at 72 beats/min. B) Without pacing, the peak
gradient was 37 mmHg at approximately 72 beats/min.
AT = acceleration time; ET = ejection time; Grad = gradient;
Pk = peak; RVOT = right ventricular outflow tract; Vmax = maximum velocity; Vmin = minimum velocity; VTI = velocity time
integral
Texas Heart Institute Journal
1. Maron MS, Hauser TH, Dubrow E, Horst TA, Kissinger KV,
Udelson JE, Manning WJ. Right ventricular involvement in
hypertrophic cardiomyopathy. Am J Cardiol 2007;100(8):
1293-8.
2. Fananapazir L, Epstein ND, Curiel RV, Panza JA, Tripodi D,
McAreavey D. Long-term results of dual-chamber (DDD)
pacing in obstructive hypertrophic cardiomyopathy. Evidence
for progressive symptomatic and hemodynamic improvement
and reduction of left ventricular hypertrophy. Circulation
1994;90(6):2731-42.
Right Ventricular Pacing in Biventricular Hypertrophic Cardiomyopathy
369