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Clinical Cases in Cardiology
Series Editors: Ravi V. Shah · Siddique A. Abbasi · James L. Januzzi
Clinical Cases
in Chronic
Thromboembolic
Pulmonary
Hypertension
William R. Auger
Deepa Gopalan Editors
Clinical Cases in Cardiology
Series Editors:
RaviV.Shah
Boston,MA,USA
SiddiqueA.Abbasi
Providence,Rhode Island,USA
JamesL.Januzzi
Boston,MA,USA
Clinical cases are a key component in modern medical ed-
ucation, assisting the trainee or recertifying clinician to
work through unusual cases using best practice techniques.
Cardiology is a key discipline in this regard and is a highly
visual subject requiring the reader to describe often very sub-
tle differences in the presentation of patients and dene ac-
curately the diagnostic and management criteria on which to
base their clinical decision-making.
This series of concise practical guides is designed to facili-
tate the clinical decision-making process by reviewing a num-
ber of cases and dening the various diagnostic and manage-
ment decisions open to clinicians.
Each title will be illustrated and diverse in scope, enabling
the reader to obtain relevant clinical information regarding
both standard and unusual cases in a rapid, easy to digest for-
mat.
More information about this series at
http://www.springer.com/series/14348
William R. Auger • Deepa Gopalan
Editors
Clinical Cases
in Chronic
Thromboembolic
Pulmonary
Hypertension
ISSN 2523-3009 ISSN 2523-3017 (electronic)
Clinical Cases in Cardiology
ISBN 978-3-030-17365-4 ISBN 978-3-030-17366-1 (eBook)
https://doi.org/10.1007/978-3-030-17366-1
© Springer Nature Switzerland AG 2020
This work is subject to copyright. All rights are reserved by the Publisher, whether
the whole or part of the material is concerned, specically the rights of transla-
tion, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on
microlms or in any other physical way, and transmission or information storage
and retrieval, electronic adaptation, computer software, or by similar or dissimi-
lar methodology now known or hereafter developed.
The use of general descriptive names, registered names, trademarks, service
marks, etc. in this publication does not imply, even in the absence of a specic
statement, that such names are exempt from the relevant protective laws and
regulations and therefore free for general use.
The publisher, the authors, and the editors are safe to assume that the advice
and information in this book are believed to be true and accurate at the date
of publication. Neither the publisher nor the authors or the editors give a
warranty, expressed or implied, with respect to the material contained herein
or for any errors or omissions that may have been made. The publisher
remains neutral with regard to jurisdictional claims in published maps and
institutional afliations.
This Springer imprint is published by the registered company Springer
Nature Switzerland AG.
The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland
Editors
William R. Auger
Lewis Katz School of Medicine
Temple University
Philadelphia, PA
USA
Deepa Gopalan
Department of Radiology
Imperial College Hospitals
London
UK
v
Preface
It might be best to first acknowledge the origins of Clinical
Cases in Chronic Thromboembolic Pulmonary Hypertension.
Having seen thousands of chronic thromboembolic disease
cases over the years, it has always been instructive as to the
diagnostic challenges presented by these patients. The ques-
tions that remain in our understanding of the natural history
of this disease, the non-specific nature of the clinical presenta-
tion, and the often indistinguishable exam findings between
CTEPH and other forms of pulmonary hypertension make an
understanding of the evaluation algorithm and the reliance on
diagnostic studies a critically important element in ultimately
establishing the diagnosis of chronic thromboembolic disease
or CTEPH.Consequently, this book focuses not on an overall
review of CTEPH as a discipline but rather provides a number
of case vignettes, each illustrating an important teaching point
that a clinician might find helpful when evaluating a patient
suspected of having CTEPH.Each case is an actual patient
presentation referred for endarterectomy surgery; the book is
proportioned to present patients who actually exhibited “typi-
cal” cases of chronic thromboembolic disease, those with clini-
cally challenging cases, as well as several examples of CTEPH
mimics. It is our hope that this book will provide a helpful
diagnostic road map for the clinician.
Chronic thromboembolic pulmonary hypertension
(CTEPH) is a form of pulmonary hypertension that results
from incomplete or non-resolution of a pulmonary embolic
burden within the proximal pulmonary arterial bed. Though
the initial embolic event can be relatively “silent” in some
vi
patients who will ultimately develop CTEPH, many patients
progress to established disease despite the acute event being
recognized and despite an appropriate course of antithrom-
botic therapy having been prescribed. The mechanism of
transition between acute and chronic thrombosis is incom-
pletely understood, as are the risk factors in any one indi-
vidual [1]. Complicating matters is that the “obstructive”
component due to organized thrombus is but a piece of the
entire clinical picture. The development of a precapillary vas-
culopathy and the establishment of systemic collateral circu-
lation “feeding” the pulmonary vasculature are also
considered operative in the establishment of the pulmonary
hypertension one sees in this disease [2, 3]. This complex
interplay contributes not only to the variability in clinical
presentation but also to a range of radiographic presentations
dependent on where any individual is in the course of their
chronic thromboembolic disease. The “pathology drives the
radiology,” and an understanding of this is critically impor-
tant to the diagnostician.
Considered to be a rare disease, the actual prevalence of
CTEPH worldwide has been difficult to determine [4]. Even
less is known when considering chronic thromboembolic dis-
ease (CTED), which is the presence of persistent, unresolved
thrombus in the absence of pulmonary hypertension or right
heart compromise [5]. The non-specificity of presenting car-
diopulmonary complaints, the variability in time course for
disease development, and the wide range of patient popula-
tions that can be affected account for some of the gaps in our
understanding of the epidemiology. But equally as important,
if not more so, are the difficulties with disease recognition
radiographically. Confusion as to the utility of ventilation- -
perfusion scintigraphy, unappreciated pulmonary vascular
and parenchymal perfusion findings by CT, and poorly under-
stood pulmonary angiographic patterns in patients with
established CTEPH contribute to the underdiagnosis of this
disease. Difficulties with the distinction between acute, acute- -
on- chronic, and chronic thromboembolic disease and the
misinformation about CTEPH “mimics” further lend to the
confusion.
Preface
vii
CTEPH is unique among other causes of pulmonary
hypertension as it is potentially possible to obtain a complete
cure in selected patients, particularly with early intervention.
Imaging is pivotal for ensuring that the appropriate diag-
nosis is made at an opportune time [6]. The primary goal of
imaging is to confirm the presence of CTEPH and evaluate
right heart function, while the secondary goal is to delineate
the distribution of the disease as a means to determine the
most appropriate therapeutic option. A single imaging tech-
nique is unlikely to provide all the requisite information, and
therefore, multimodality imaging is widely used in clinical
practice.
Transthoracic echocardiography is a simple but indispens-
able noninvasive tool that is routinely employed as the first
step in the diagnostic pathway. There are several publications
detailing the various echocardiographic parameters that are
useful in PH evaluation. However, it is well recognized that
echocardiography relying predominantly on Doppler pres-
sure estimates can miss PH in as many as 10–30%, particu-
larly in the early stages of the disease. Technical advances
such as three-dimensional (3D) echocardiography can over-
come the challenges presented by the complex RV geometry,
while RV strain imaging can potentially detect subclinical
pulmonary hypertension.
In a patient with known or suspected pulmonary hyperten-
sion, it is necessary to confirm or exclude CTEPH earlier on
in the diagnostic pathway. Ventilation-perfusion (VQ) scin-
tigraphy is the most sensitive test in the diagnostic algorithm
for excluding CTEPH. A normal perfusion scan carries a
high negative predictive valve, and hence, VQ is invaluable as
a simple but effective screening tool. However, its high sensi-
tivity is unfortunately not matched by high specificity, and
there are various conditions in addition to CTEPH that are
associated with mismatched perfusion defects. Examples of
these CTEPH mimics are illustrated in this atlas.
Any patient with a mismatched perfusion defect will
require downstream anatomical testing. The vascular abnor-
malities of CTEPH have been extensively described in the
Preface
viii
literature and include eccentric thrombus that may or may
not be calcified, intravascular webs, and stenosis with or
without post-stenotic dilatation and pouch defects. The ves-
sel may be completely occluded or show abrupt truncation
with attenuated segmental branches. Systemic collateral ves-
sels (bronchial and non-bronchial) are a feature of chronic-
ity. All these features can be delineated using noninvasive
techniques such as computed tomography pulmonary angi-
ography (CTPA) and magnetic resonance pulmonary angi-
ography (MRPA) or by the more conventional catheter
pulmonary angiography.
While CTPA is now considered as the standard of care for
acute PE, its role in the diagnosis of CTEPH is tinged with
controversy. There is a well-recognized variability in the diag-
nostic performance of CTPA in CTEPH that can be partially
attributed to relative rarity of the disease and the lack of
awareness among the imaging community. The lower CT tem-
poral resolution compared to catheter angiography contrib-
utes to the suboptimal delineation of the distal pulmonary
vasculature. This can be circumvented by employing contem-
porary techniques such as dual-energy CT (DECT) that
allow for simultaneous evaluation of pulmonary vascular
morphology and lung perfusion abnormalities, but as of now,
this lacks prospective validation and hence cannot be man-
dated for incorporation into routine clinical practice.
Although CT, MR, and catheter angiography are often con-
sidered to be complementary, corroborative information such
as mosaic attenuation, another useful discriminator for chro-
nicity in patients with suspected acute or acute-on- chronic
disease, can be depicted using CTPA, while the bronchopulmo-
nary shunt fraction can be calculated using MR.Cardiac MR is
also the reference standard for evaluation of ventricular func-
tion. There is a growing body of evidence demonstrating the
value of multiparametric MR techniques for characterization
of RV structure and physiology, but their clinical utility in
CTEPH is yet to be proven. Multidirectional 4D phase-con-
trast MR is a compelling evolving tool for evaluation of the
complex flow patterns within the RV and pulmonary circula-
Preface
ix
tion and could potentially be useful as a screening tool in iden-
tifying subclinical PH in the future.
A few high-volume clinical centers with experience in non-
invasive imaging routinely use the road maps of the pulmo-
nary vasculature obtained from CT and MR for operability
assessment, but most institutions still resort to catheter angi-
ography for this evaluation. Conventional angiography can
be tagged to a right heart catheter examination, eliminating
the need for a separate puncture. While proven to be a safe
technique in accomplished hands, it is not without complica-
tions. Considerable technical expertise is required to ensure
that appropriate views are undertaken without excessive
exposure to radiation and iodinated contrast medium. This
involves a fine balance between acquiring orthogonal views
following selective or super selective engagement of the cath-
eter into the vessel under consideration and observing the
capillary phase for perfusion defects.
The advent of balloon pulmonary angioplasty has led to
further refinement of this technique. Rotational angiography
and cone-beam CT are used in conjunction with the catheter
angiography to get exquisite images of the pulmonary arterial
tree to the subsegmental level.
That multimodality imaging contributes vital information
for CTEPH diagnosis as well as to the decision-making pro-
cess for disease management is incontrovertible. Some physi-
cians and surgeons are accustomed to interpreting the
imaging data without active input from radiologists. While
there is no doubt that some clinicians are seasoned veterans
with years of experience in dealing with CTEPH, they may
still fail to understand the nuances of the different imaging
modalities and miss subtle but crucial findings. It is best to
involve a pulmonary vascular imaging specialist who is con-
versant with the contemporary techniques and understands
the subtleties involved. Most international guidelines and
scientific statements emphasize the need for suspected or
confirmed CTEPH cases to be referred to an expert center
for discussion by a multidisciplinary team in which a radiolo-
gist performs an essential role.
Preface