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JACC: Heart Failure
2014 by the American College of Cardiology Foundation
Published by Elsevier Inc.
Vol. 2, No. 1, 2014
ISSN 2213-1779/$36.00
http://dx.doi.org/10.1016/j.jchf.2013.07.009
Characterization of a Novel Symptom
of Advanced Heart Failure: Bendopnea
Jennifer T. Thibodeau, MD, MSC, Aslan T. Turer, MD, MHS, Sarah K. Gualano, MD,
Colby R. Ayers, MS, Mariella Velez-Martinez, MD, Joseph D. Mishkin, MD, Parag C. Patel, MD,
Pradeep P. A. Mammen, MD, David W. Markham, MD, MSC, Benjamin D. Levine, MD,
Mark H. Drazner, MD, MSC
Dallas, Texas
Objectives
This study sought to examine the frequency and hemodynamic correlates of shortness of breath when bending
forward, a symptom we have termed “bendopnea.”
Background
Many heart failure patients describe bendopnea such as when putting on their shoes. This symptom has not
previously been characterized.
Methods
We conducted a prospective study of 102 subjects with systolic heart failure referred for right-heart catheterization.
Time to onset of bendopnea was measured prior to catheterization. Forty-six subjects also underwent hemodynamic
assessment when sitting and bending. Hemodynamic profiles were assigned on the basis of whether pulmonary
capillary wedge pressure (PCWP) was 22 mm Hg and cardiac index (CI) was 2.2 l/min/m2.
Results
Bendopnea was present in 29 of 102 (28%) subjects with median (25th, 75th percentiles) time to onset of
8 (7, 11) seconds. Subjects with bendopnea had higher supine right atrial pressure (RAP) (p ¼ 0.001) and PCWP
(p ¼ 0.0004) than those without bendopnea but similar CI (p ¼ 0.2). RAP and PCWP increased comparably
in subjects with and without bendopnea when bending, but CI did not change. In those with, versus without,
bendopnea, there was more than a 3-fold higher frequency of a supine hemodynamic profile consisting of elevated
PCWP with low CI (55% vs. 16%, respectively, p < 0.001) but no association with a profile of elevated PCWP with
normal CI (p ¼ 0.95).
Conclusions
Bendopnea is mediated via a further increase in filling pressures during bending when filling pressures are
already high, particularly if CI is reduced. Awareness of bendopnea should improve noninvasive assessment of
hemodynamics in subjects with heart failure. (J Am Coll Cardiol HF 2014;2:24–31) ª 2014 by the American
College of Cardiology Foundation
Shortness of breath, a dominant symptom in patients with
heart failure, is subclassified on the basis of the activity that
provokes its onset. Dyspnea with exertion, orthopnea and
paroxysmal nocturnal dyspnea, criteria used to define heart
failure by the Framingham Heart Study in 1971 (1),
continue to be used in routine clinical practice to classify
breathlessness. Recently, we have noticed that many heart
failure patients describe shortness of breath specifically when
bending forward, such as when putting on their shoes or
socks. To our knowledge, this symptom has not previously
been characterized. In order to determine the potential
mechanism and clinical implications of this symptom, we
conducted the present prospective study to examine the
frequency and hemodynamic correlates of shortness of
breath when bending forward, or “bendopnea,” in heart
failure patients with systolic dysfunction who were referred
for right heart catheterization.
See page 32
From the Division of Cardiology, Department of Internal Medicine, University of
Texas Southwestern Medical Center, Dallas, Texas. Dr. Markham has a financial
relationship with Thoratec. Dr. Drazner has received support from the James M.
Wooten Chair in Cardiology. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose. This study was presented
in part at the American Heart Association Scientific Sessions as part of the Samuel
Levine Young Clinical Investigator Award session on November 3, 2012.
Manuscript received July 19, 2013; accepted July 25, 2013.
Methods
Study design and subject selection. We conducted a singlecenter prospective observational study of a convenience sample of 102 subjects with systolic heart failure who were
referred for right heart catheterization at the University of
JACC: Heart Failure Vol. 2, No. 1, 2014
February 2014:24–31
Texas Southwestern Medical Center for clinical indications
between June 2010 and May 2012. Inpatient or outpatient
subjects 18 years of age or older with systolic heart failure,
defined as a left ventricular ejection fraction (LVEF) 40%
within the previous 3 months, were eligible for enrollment. Subjects were excluded if they had undergone cardiac transplantation or required mechanical circulatory support with
an intra-aortic balloon pump or ventricular assist device. The
study protocol was reviewed and approved by the institutional
review board. All subjects gave written informed consent.
Clinical assessment. A history and physical examination
were completed for each subject by an investigator within
6 h prior to right-heart catheterization. Data collected
included demographic data, medical history, cardiac medications, etiology of cardiomyopathy, peak oxygen consumption, LVEF determined within 3 months of
enrollment, and assessment of functional status by New
York Heart Association (NYHA) classification system (2).
In order to determine the presence of bendopnea, each
subject sat in a chair and bent forward at the waist as if
putting on their socks or shoes, while an investigator timed
the duration to the onset of shortness of breath, as stated to
the patient “tell me when you feel short of breath.” While
some patients reported lightheadedness or fullness of the
head, chest, or abdomen, the symptom that we describe as
bendopnea is specifically shortness of breath when bending
forward. This maneuver was performed after consent was
obtained but prior to the subject entering the catheterization
suite. The subject was classified as having bendopnea if they
reported shortness of breath within 30 sec of bending. In
addition, subjects were queried regarding the presence of the
following symptoms within 7 days prior to enrollment:
angina, dyspnea on exertion (if present, the number of
blocks before symptom onset), orthopnea, paroxysmal
nocturnal dyspnea, weight gain, lower extremity swelling,
abdominal fullness or pressure, early satiety, nausea or
vomiting, palpitations, syncope, and defibrillator firing.
Physical examination included height, weight, and body
mass index (BMI) on the day of enrollment as recorded in
the clinical chart, measurement of waist and hip circumference, estimation of jugular venous pressure (JVP), and
assessment of the presence of a third heart sound, rales, and
lower extremity edema. Laboratory values from the clinical
chart were recorded if they were within 1 week of enrollment
and included hemoglobin, creatinine, and natriuretic peptide
concentration. Estimated glomerular filtration rate was
determined by the Modification of Diet in Renal Disease
equation (3). Due to a change in assay availability at our
institution, B-type natriuretic peptide concentrations were
measured in the first 54 subjects, whereas subsequent subjects had N-terminal pro-B-type natriuretic peptide concentrations measured.
Hemodynamic assessments. SUPINE MEASUREMENTS. Interventional cardiologists who were blinded to the results of
the clinical assessment and determination of bendopnea
status performed the right-heart catheterization. All
Thibodeau et al.
Characterization of Bendopnea
25
enrolled subjects underwent
Abbreviations
and Acronyms
routine right-heart catheterization while lying in the supine
BMI = body mass index
position. Beat-by-beat arterial
CI = cardiac index
blood pressure measurements
LVEF = left ventricular
were taken by using finger phoejection fraction
toplethysmography
(Finapres,
JVP = jugular venous
Ohmeda, Englewood, Colorado),
pressure
and heart rate was determined
NYHA = New York Heart
from a 3-lead electrocardiogram.
Association
Dual pressure transducers were
PCWP = pulmonary capillary
used to allow simultaneous meawedge pressure
surement of right atrial pressure
PVR = pulmonary vascular
(RAP) and pulmonary capillary
resistance
wedge pressure (PCWP). The
RAP = right atrial pressure
mean pressures were used for the
SVR = systemic vascular
RAP and PCWP. The PCWP
resistance
was confirmed by oxygen saturation in two-thirds of subjects and by waveform inspection in
the remaining cases. All pressure measurements were obtained at end expiration. Cardiac output was obtained using
both the thermodilution and the Fick methods. For the Fick
equation, oxygen consumption was estimated according to the
derived formula programmed into the Xper Flex Cardio
(Philips, Andover, Massachusetts) physiomonitoring system
(4) used in our catheterization suite, as follows: VO2 (ml/
min) ¼ 133 ml/min/m2 body surface area (m2), where
body surface area was calculated according to the formula of
Dubois and Dubois (5): [0.007184 weight (kg)0.425 height (cm)0.725]. Thermodilution cardiac output measurements were obtained at least in triplicate and averaged such
that all included values were within 10% of the mean. Cardiac
index (CI) was calculated as the cardiac output indexed to
body surface area.
A subset of
the cohort who consented to additional measurements
(n ¼ 46) also underwent hemodynamic assessment when
sitting upright in a chair and when sitting in a chair while
bending forward at the waist. Location of the right atrial
site was determined under fluoroscopy at the beginning
of the catheterization procedure, and the corresponding
skin site was marked for leveling purposes. After completion of the standard supine right-heart catheterization,
subjects were moved to a chair and repeat assessment of
hemodynamics was performed after releveling of the
pressure transducers and at least 2 min of rest. The subjects
then bent forward at the waist as if tying their shoes
and underwent repeat hemodynamic assessment after releveling of the pressure transducers and at least 1 min of
bending. The presence of bendopnea was also reassessed
at this time.
Definitions. Subjects were classified into 1 of 4 hemodynamic profiles, as advocated by other investigators (6),
based on the basis of invasively-measured left ventricular
filling pressures and CI: profile A, “warm and dry”:
MEASUREMENTS WHEN SITTING AND BENDING.
26
Thibodeau et al.
Characterization of Bendopnea
CI >2.2 l/min/m2, PCWP <22 mm Hg; profile B, “warm
and wet”: CI >2.2 l/min/m2, PCWP 22 mm Hg; profile
C, “cold and wet”: CI 2.2 l/min/m2, PCWP 22 mm Hg;
and profile L, “cold and dry”: CI 2.2 l/min/m2,
PCWP <22 mm Hg.
Statistical analysis. We estimated that 30% of enrolled
subjects would have bendopnea. Given this proportion, a
total of 100 subjects would allow a power of 90% to detect a
5 mm Hg change in RAP and PCWP, assuming a standard
deviation of 7 (7); and a power of over 95% to detect a 0.5
l/min/m2 change in CI, assuming a standard deviation of
0.6 (7). Descriptive statistics are reported as median (25th,
75th percentiles) or as numbers (%), as appropriate. The
chi-square test (categorical variables) and the Wilcoxon rank
sum test (continuous variables) were used for comparison
of clinical characteristics of the bendopnea and the nobendopnea groups. In cases of low cell counts, the Fisher’s
exact test was used for comparison of the categorical variables.
For the primary outcome of differences in hemodynamic
parameters when supine, the Wilcoxon rank sum test was used
to compare the median values between subjects with
and without bendopnea. The Wilcoxon rank sum test was
also used to compare the median values of the hemodynamic
parameters of those with and without bendopnea at each
position and to assess comparisons in the change in hemodynamics across supine, sitting, and bending positions. Statistical significance was set at 0.05, and all tests were 2-tailed.
Statistical analyses were conducted using SAS version
9.2 software (SAS Institute, Inc., Cary, North Carolina).
Results
Clinical characteristics. Bendopnea was present in 29 of
102 (28%) subjects. In those with bendopnea, the median
(25th, 75th percentiles) time to symptom onset was 8 (7, 11)
seconds. The clinical characteristics of subjects with and
without bendopnea are summarized in Table 1. Most subjects
were white, male, 60 to 65 years of age, and NYHA functional
classes III and IV, with an LVEF of approximately 20%. Most
subjects were taking angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, beta-blockers, and
diuretics. Subjects with bendopnea were more likely to have
other symptoms of decompensated heart failure, including
angina, dyspnea on exertion, orthopnea, paroxysmal nocturnal
dyspnea, and abdominal fullness or pressure. BMI was higher
in subjects with bendopnea than in those without, but there
were no differences in waist or hip circumferences and waist/
hip ratios between these 2 groups. On physical examination,
the only sign associated with bendopnea was an elevated JVP.
There were no differences between subjects with and without
bendopnea with respect to renal function, hemoglobin, and
natriuretic peptide concentrations.
Supine hemodynamic findings. Supine hemodynamics for
subjects with and without bendopnea are summarized in
Table 2. Subjects with bendopnea had higher RAP
and PCWP and lower pulmonary artery oxygen saturation
JACC: Heart Failure Vol. 2, No. 1, 2014
February 2014:24–31
and CI calculated using the Fick equation. There was no
difference in the thermodilution CI between subjects with and
without bendopnea (p ¼ 0.17). Additionally, there were no
difference in mean arterial pressure, heart rate, pulmonary
vascular resistance (PVR), or systemic vascular resistance
(SVR) between those with and without bendopnea.
Changes in hemodynamics with position. Of the 46 patients who underwent repeat hemodynamic assessment when
bending, 16 (35%) had bendopnea and 30 (65%) did not
(Online Table 1). Median RAP in subjects with bendopnea
(compared to those without bendopnea) when sitting was
10 (6, 14) mm Hg versus 4 (2, 9) mm Hg, respectively (p ¼
0.02), and 19 (10, 26) mm Hg versus 12 (7, 18) mm Hg when
bending, respectively (p ¼ 0.07) (Fig. 1). This increase in
RAP with bending was significant in both groups (p 0.0001
for both), but there was no difference in the amount of increase between these groups [11 (2, 15) mm Hg vs. 7 (3, 10)
mm Hg, respectively, p ¼ 0.24]. Subjects with bendopnea had
higher median PCWP when sitting than those without
[27 (19, 30) mm Hg vs. 13 (8, 22) mm Hg, respectively, p ¼
0.003] and also when bending [35 (29, 41) mm Hg vs. 22 (16,
35) mm Hg, respectively, p ¼ 0.01]. As with RAP, PCWP
increased when bending in subjects with and without bendopnea (p 0.0001 for both), but there was no difference in the
amount of increase between these groups (p ¼ 0.90). In
contrast to the above findings, thermodilution CI did not
differ between those with and those without bendopnea
when sitting or bending (p ¼ 0.34 and p ¼ 0.42, respectively), nor did thermodilution CI change when bending
either in subjects with or without bendopnea (p ¼ 0.40).
There were no differences in SVR or PVR between those
with and those without bendopnea at all positions, and there
were no changes in SVR or PVR with position change in
either those with or without bendopnea (p > 0.05 for
all).There was 100% agreement in bendopnea status
assessed at study enrollment and during catheterization.
Mean arterial pressure, heart rate, SVR, PVR, transpulmonary gradient (mean PAP PCWP) and transmural
gradient (PCWP RAP) (8–10) were similar in subjects
with and without bendopnea at each position and did not
significantly increase or decrease with position change
(data not shown).
Distribution of hemodynamic profiles, stratified by
bendopnea. As shown in Figure 2, subjects with bendopnea were predominantly hemodynamic profile C,
whereas subjects without bendopnea were predominantly
profiles A and L. To ensure that the increase in frequency
of hemodynamic profile C and not profile B in those
with bendopnea was not due to a higher PCWP in the
former group, we compared the median PCWP values of
these 2 profiles. Overall, the median PCWP in subjects
who were profile B and C were similar [24 (22, 26) mm Hg
and 25 (23, 28) mm Hg, respectively, p ¼ 0.2]. Additionally, the median PCWPs were similar in profile B and
C subjects with bendopnea [26 (24, 26) mm Hg and 25
(23, 29) mm Hg, respectively, p ¼ 1.0] and without
JACC: Heart Failure Vol. 2, No. 1, 2014
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Table 1
Thibodeau et al.
Characterization of Bendopnea
Clinical Characteristics of Subjects With and Without Bendopnea
Characteristic
Subjects With Bendopnea
(n ¼ 29)
Subjects Without Bendopnea
(n ¼ 73)
p Value
Age yrs
58 (50, 65)
64 (54, 68)
0.07
Male
20 (69%)
57 (78%)
0.33
20 (69%)
52 (71%)
Black
8 (28%)
17 (23%)
Hispanic
1 (3%)
3 (4%)
Race
Caucasian
0.90
Medical history
COPD
2 (7%)
8 (11%)
0.72
Atrial fibrillation
6 (21%)
18 (25%)
0.67
Diabetes
12 (41%)
29 (40%)
0.88
Hypertension
12 (41%)
47 (64%)
0.03
Hyperlipidemia
16 (55%)
43 (59%)
0.73
Smoking
15 (52%)
39 (53%)
0.88
Severe mitral regurgitation
3 (10%)
9 (12%)
0.78
Severe tricuspid regurgitation
2 (7%)
10 (14%)
0.50
Current medications
Angiotensin-converting enzyme inhibitor
Amiodarone
Angiotensin receptor blocker
15 (52%)
47 (64%)
0.24
6 (21%)
23 (32%)
0.28
0.19
6 (21%)
7 (10%)
Aldosterone antagonist
15 (52%)
24 (33%)
0.08
Aspirin
17 (59%)
54 (74%)
0.13
Beta-blocker
26 (90%)
58 (80%)
0.22
Digoxin
15 (52%)
29 (40%)
0.27
Diuretic
23 (79%)
64 (88%)
0.35
HMG-CoA reductase inhibitor
12 (41%)
53 (73%)
0.003
Long-acting nitrate or hydralazine
7 (24%)
21 (29%)
0.64
Inotropic therapy
6 (21%)
8 (11%)
0.21
Ischemic cause of cardiomyopathy
12 (41%)
42 (58%)
0.14
LVEF, %
21 (19, 25)
20 (15, 28)
0.55
Peak oxygen consumption,
ml/kg/min (n ¼ 43)
14.5 (11.3, 15.4)
12.8 (12.0, 16.4)
0.88
NYHA class I
0 (0%)
4 (6%)
0.58
NYHA class II
2 (7%)
12 (16%)
0.34
NYHA class III
16 (55%)
48 (66%)
0.32
NYHA class IV
11 (38%)
9 (12%)
0.003
Angina
13 (45%)
10 (14%)
0.001
Dyspnea on exertion
29 (100%)
58 (80%)
0.005
Number of blocks before dyspnea
0.5 (0.5, 1.0)
1.0 (0.5, 3.0)
0.003
Orthopnea
18 (62%)
21 (29%)
0.002
Symptoms in the preceding 7 days of
Paroxysmal nocturnal dyspnea
17 (59%)
17 (23%)
0.001
Weight gain
14 (48%)
15 (21%)
0.001
Lower extremity swelling
8 (28%)
11 (15%)
0.14
Abdominal fullness or pressure
23 (79%)
24 (33%)
<0.001
Early satiety
20 (69%)
36 (49%)
0.07
Nausea/vomiting
10 (35%)
14 (19%)
0.10
Palpitations
12 (41%)
13 (18%)
0.01
3 (10%)
3 (4%)
0.35
10 (35%)
7 (10%)
Syncope
Near syncope
0.006
Continued on next page
27
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Thibodeau et al.
Characterization of Bendopnea
Table 1
JACC: Heart Failure Vol. 2, No. 1, 2014
February 2014:24–31
Continued
Characteristic
Subjects With Bendopnea
(n ¼ 29)
Subjects Without Bendopnea
(n ¼ 73)
p Value
Physical examination findings
BMI, kg/m2
30 (28, 34)
27 (24, 31)
Waist circumference, in
44 (38, 47)
40 (35, 44)
0.17
Hip circumference, in
42 (37, 48)
39 (37, 44)
0.34
Waist/hip ratio
Jugular venous pressure, cm
1.02 (0.94, 1.05)
10 (7, 14)
0.98 (0.93, 1.03)
7 (5, 9)
0.01
0.29
0.01
Third heart sound
1 (4%)
1 (1%)
0.50
Rales
5 (17%)
8 (11%)
0.51
Lower extremity or dependent edema
8 (28%)
12 (16%)
0.20
Laboratory values
Hemoglobin level, g/dl
12.8 (11.1, 14.6)
12.8 (11.5, 13.6)
0.60
Creatinine level, mg/dl
1.2 (1.0, 1.6)
1.4 (1.1, 1.7)
0.40
55 (40, 84)
55 (40, 74)
0.69
389 (281, 680)
395 (159, 676)
0.68
eGFR level, ml/min/1.73 m2
BNP level, pg/ml (n ¼ 54)
NT-proBNP level, pg/ml (n ¼ 30)
2,719 (1,142, 4,008)
2,536 (1,346, 8,359)
0.56
Values are median (25th, 75th percentiles) or n (%).
BMI ¼ body mass index; BNP ¼ B-type natriuretic peptide; COPD ¼ chronic obstructive pulmonary disease; eGFR ¼ estimated glomerular filtration
rate; LVEF ¼ left ventricular ejection fraction; NT-proBNP ¼ N-terminal pro-B-type natriuretic peptide; NYHA ¼ New York Heart Association.
bendopnea [24 (22, 25) mm Hg and 27 (23, 28) mm Hg,
respectively, p ¼ 0.1]. The median increase in the PCWP
with bending was 9 (2, 11) mm Hg in profile B subjects and
11 (6, 16) mm Hg in profile C subjects (p ¼ 0.28).
Discussion
Our study is the initial characterization of a novel symptom
of heart failure, shortness of breath with bending forward,
which we have termed bendopnea. Bendopnea was present
Table 2
in a sizable minority (approximately one-third) of the study
cohort, was reproducible when reassessed later the same day,
and was associated with hemodynamic derangements; specifically, elevated right ventricular and left ventricular filling
pressures. Additionally, when subjects were categorized
into 1 of 4 hemodynamic profiles on the basis of elevation of
left ventricular filling pressures and adequacy of cardiac
perfusion (6), we found that a profile of high PCWP with a
low CI was significantly more common in those with
bendopnea. Finally, by measuring ventricular filling
Supine Hemodynamic Findings for Subjects With and Without Bendopnea
Characteristic
Subjects With Bendopnea
(n ¼ 29)
Subjects Without Bendopnea
(n ¼ 73)
p Value
RAP, mm Hg
11 (7, 15)
5 (3, 10)
0.001
RVSP, mm Hg
49 (42, 66)
42 (25, 53)
0.004
PASP, mm Hg
48 (42, 62)
42 (26, 52)
0.006
PADP, mm Hg
24 (20, 30)
20 (12, 25)
0.003
Mean PAP, mm Hg
33 (30, 44)
30 (19, 36)
0.003
PCWP, mm Hg
23 (20, 26)
19 (8, 23)
0.0004
Transpulmonary gradient, mm Hg
10 (8, 16)
11 (7, 14)
0.55
Transmural gradient, mm Hg
12 (10, 15)
10 (4, 15)
0.05
PA saturation, %
57 (48, 59)
61 (54, 65)
0.003
CI by Thermodilution method, l/min/m2
2.1 (1.8, 2.6)
2.3 (2.0, 2.5)
0.17
CI by Fick method, l/min/m2
2.0 (1.8, 2.2)
2.4 (2.1, 2.6)
0.001
MAP, mm Hg
82 (74, 94)
84 (76, 93)
0.59
Heart rate, beats/min
76 (66, 87)
76 (69, 84)
0.84
PVR by thermodilution method, Woods units
2.4 (1.8, 3.9)
2.7 (1.6, 3.5)
0.41
PVR by Fick method, Woods units
2.4 (1.9, 4.3)
2.2 (1.7, 3.3)
0.19
SVR by thermodilution method, dyne/s/cm5
1,319 (1,115, 1,555)
1,396 (1,134, 1,615)
0.62
SVR by Fick method, dyne/s/cm5
1,433 (1,243, 1,624)
1,327 (1,099, 1,558)
0.18
Values are median (25th, 75th percentiles).
CI ¼ cardiac index; PADP ¼ pulmonary artery diastolic pressure; PA ¼ pulmonary artery; PAP ¼ pulmonary artery pressure; PASP ¼ pulmonary
artery systolic pressure; PCWP ¼ pulmonary capillary wedge pressure; PVR ¼ pulmonary vascular resistance; RAP ¼ right atrial pressure;
RVSP ¼ right ventricular systolic pressure; SVR ¼ systemic vascular resistance.
JACC: Heart Failure Vol. 2, No. 1, 2014
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Thibodeau et al.
Characterization of Bendopnea
Figure 2
29
Distribution of Hemodynamic Profiles,
Stratified by Bendopnea
When comparing subjects with bendopnea to those without bendopnea, there was
an increase in the frequency of profile C in the former (55% vs. 16%, respectively,
p < 0.0001) and a trend toward an increase in the frequency of profile A (p ¼ 0.07)
and in profile L (p ¼ 0.048) in the latter. There was no significant difference in the
frequency of profile B (p ¼ 0.95) in this comparison. The number of subjects
without bendopnea in profile A was 26, 13 in B, 11 in C, and 21 in D; the number
of subjects with bendopnea in profile A was 5, 5 in B, 16 in C, and 3 in L.
Figure 1
Changes in Hemodynamic Parameters From
Sitting to Bending, Stratified by Bendopnea
(A) Right atrial pressure and (B) pulmonary capillary wedge pressure were higher
while sitting in subjects with bendopnea than in those without bendopnea (n ¼ 46;
n ¼ 16 with bendopnea, n ¼ 30 with no bendopnea; p < 0.05 for all). Pressures
increased significantly from sitting to bending in those with or without bendopnea
(p 0.0001 for all). However, there was no significant difference in the amount of
increase between those with and without bendopnea (p ¼ 0.24 for RAP, p ¼ 0.90
for PCWP). (C) Cardiac index by thermodilution was similar between those with and
without bendopnea either when sitting or bending (p ¼ 34 and p ¼ 0.42,
respectively) and did not change from sitting to bending in those with (p ¼ 0.38) or
without bendopnea (p ¼ 0.40).
pressures and CI in subjects when they bent forward, we
found that bending led to an increase in ventricular filling
pressures but no reduction in the cardiac index.
Previous studies have assessed the association of heart
failure signs and symptoms with invasively measured hemodynamics. Orthopnea has been shown to be the symptom
best correlated with elevated left ventricular filling pressures measured in the supine position (6,11,12). In the
ESCAPE (Evaluation Study of Congestive Heart Failure
and Pulmonary Artery Catheterization Effectiveness),
orthopnea within the last week was associated strongly
with very high PCWPs (e.g., 28 to 30 mm Hg) (11). In our
current study, bendopnea (confirmed present on the day of
the right heart catheterization) was also associated with
elevated PCWP when measured in the supine and sitting
positions and when subjects bent forward. Furthermore,
orthopnea was 2-fold more common in those with bendopnea, a finding consistent with the hypothesis that both
symptoms have the same underlying pathophysiological
mechanism (i.e., elevated left ventricular filling pressures).
As with symptoms, signs detected on physical examination
also have been shown to be associated with elevated left
ventricular filling pressures. In the ESCAPE trial, elevated
JVP was the only physical examination finding associated
with elevated PCWP (11). This finding is consistent with
the present study where elevated JVP was the only physical
examination finding associated with bendopnea (Table 1).
One of the objectives of the present study was to determine the pathophysiological basis of bendopnea. First, we
wanted to confirm that bendopnea was not simply related to
body habitus (i.e., increased abdominal girth). Although
BMI was higher in those with bendopnea, we found there
were no differences in waist circumference or waist/hip
30
Thibodeau et al.
Characterization of Bendopnea
ratio in those with bendopnea, suggesting that increased
abdominal girth was not the primary cause of bendopnea.
Second, we wanted to determine whether bendopnea was
related to elevated ventricular filling pressures or to a
reduction in CI during bending. We found that subjects
with bendopnea had higher ventricular filling pressures than
those without, both in the supine and sitting positions.
Furthermore, there was a significant increase in both right
and left ventricular filling pressures during bending (Fig. 1),
consistent with an increase in intrathoracic pressure. We
interpret these data to suggest that during bending,
increased intrathoracic pressure leads to a further increase in
ventricular filling pressures, and subjects with bendopnea
(who start with higher filling pressures) are more likely to
reach a threshold pressure necessary to induce shortness of
breath. We hypothesize that bendopnea is likely caused by
elevation in the left-sided filling pressure, or PCWP, as has
been demonstrated with other manifestations of shortness of
breath in patients with heart failure (13–15). However,
because right- and left-sided ventricular filling pressures
often track together in patients with chronic heart failure
(13–15), we cannot exclude with certainty the fact that
further elevation of RAP also contributed to bendopnea. In
contrast to the above-mentioned changes in filling pressures,
we found that the CI as measured by the thermodilution
method did not change significantly with bending, suggesting that a fall in CI with bending was not the cause of
bendopnea. Nevertheless, a low CI appears to have some
contributory role in this symptom given that hemodynamic
profile C (elevated PCWP and low CI) but not profile B
(elevated PCWP and adequate CI) was associated with
bendopnea, even though the PCWP among those with
profile C was no higher than those with profile B. However,
we recognize that the number of subjects with profile B was
relatively small in our study (n ¼ 18) and that it may have
been underpowered to detect an association with bendopnea.
Clinical implications of bendopnea. Assessing hemodynamics by history and physical examination is important both
for prognostic and therapeutic purposes. Evidence of
congestion has been shown to portend poor prognosis
(16–21). For example, in a retrospective analysis of the
SOLVD (Studies Of Left Ventricular Dysfunction) treatment trial, an elevated JVP was associated with a significantly
increased risk of all-cause mortality, hospitalization for heart
failure, and death from pump failure (17). Additionally, in
those with advanced heart failure, lack of congestion at hospital discharge (11) or at a follow-up clinic visit after hospital
discharge (22) was associated with improved outcomes. Thus,
the prognostic utility of bendopnea should be assessed. In
particular, bendopnea may have utility for physicians who are
not adept at estimating jugular venous pressure.
Study limitations. The number of subjects enrolled was
relatively small, particularly when assessing hemodynamics
during postural changes. Nevertheless, we were able to
document specific hemodynamic changes that occur with
bending. We confirmed the PCWP with oxygen saturation
JACC: Heart Failure Vol. 2, No. 1, 2014
February 2014:24–31
in the supine but not sitting and bending positions. We
estimated oxygen consumption rather than directly
measuring it. However, having subjects breathe into a
metabolic cart might have influenced their perception of
bendopnea. The thermodilution method was used to measure cardiac output, and this approach can be inaccurate in
low-output states or with severe tricuspid regurgitation or
irregular rhythms (23). However, determination of cardiac
output by thermodilution is used in clinical practice and
forms the basis of routine medical decision making. Additionally, the thermodilution method was used in the National Heart, Lung, and Blood Institute-sponsored
ESCAPE trial (7). Another limitation was that assessment
of other symptoms of heart failure was by subject recall over
the previous week and not determined on the day of their
right-heart catheterization; thus, comparison of other
symptoms of heart failure with bendopnea is limited.
However, this was not the main focus of our study. Some
patients with bendopnea did not have elevated PCWP,
suggesting that factors other than elevated left ventricular
filling pressures can cause this symptom. Nevertheless, our
data show that in many patients, bendopnea is a marker of
an elevated PCWP. We enrolled a convenience sample of
patients that was based on the availability of the investigator
and the cardiac catheterization laboratory to enroll research
patients. However, the convenience sampling was due
neither to the severity of illness nor the presence or absence
of bendopnea. Our study cohort consisted of patients who
were referred for right-heart catheterization, many of whom
had advanced heart failure. As such, additional studies are
needed to determine the prevalence of bendopnea among
the general heart failure population.
Conclusions
Bendopnea, a newly described symptom in patients with
heart failure, is mediated via a further increase in ventricular
filling pressures during bending in subjects whose sitting
ventricular filling pressures are already high, particularly in
patients with low CI. Awareness of this symptom by physicians should improve their noninvasive assessment of hemodynamics in patients with heart failure.
Reprint requests and correspondence: Dr. Mark H. Drazner,
University of Texas Southwestern Medical Center, 5323 Harry
Hines Boulevard, Dallas, Texas 75390-9047. E-mail: mark.
[email protected].
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Key Words: dyspnea
-
heart failure
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hemodynamics.
APPENDIX
For a supplemental table, please see the online version of this paper.