Europace Advance Access originally published online on March 13, 2008
Europace 2008 10(4):482-485; doi:10.1093/europace/eun062
Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2008. For permissions please email: journals.permissions@oxfordjournals.org
SYNCOPE: THE ROLE OF SYNCOPE UNIT
Postural tachycardia syndrome and coronary artery bridge
Sahar S. Abdelmoneim1,
Sherif Moustafa2 and
Farouk Mookadam1,*
1 Mayo Cardiovascular Ultrasound Imaging and Hemodynamic Laboratory, Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic, Rochester, MN, USA;
2 Department of Cardiology, Montreal Heart Institute, University of Montreal, Montreal, QC, Canada H1T 1C8
Manuscript submitted 13 December 2007. Accepted after revision 19 February 2008.
* Corresponding author: Mayo Clinic Arizona, 13400 E Shea Blvd, Scottsdale, AZ 85259-5499, USA. Tel: +1 480 301 6201; fax: +1 480 301 8018. E-mail address: mookadam.farouk{at}mayo.edu
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Abstract
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Postural tachycardia syndrome (POTS) is characterized by the
presence of orthostatic tachycardia in the absence of orthostatic
hypotension with a heart rate increase of
30 bpm. Patients often
relate complaints of palpitations, exercise intolerance, fatigue
and near-syncope or syncope, other non-specific symptoms such
as headache and nausea may be present as well to varying degrees.
Myocardial bridging is rare occurring in 0.5–16% in angiographic
studies. Clinical presentation is protean and can manifest as
atrioventricular blockade, ventricular tachycardia, myocardial
ischaemia, sudden cardiac death, and myocardial infarction.
However, the majority of patients with myocardial bridging are
asymptomatic. We describe a case of POTS syndrome and myocardial
bridging co-existing and presenting a therapeutic challenge.
Key Words: Postural tachycardia syndrome, Myocardial bridge
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Case
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A 59-year-old lady with a longstanding history of palpitations
and syncopal attacks presented with exertional chest pain that
is relieved with rest or sublingual nitroglycerin. Past medical
history was unremarkable except for degenerative spondylosis
of the spine. Physical examination was notable for rapid regular
pulse, noted to be a sinus tachycardia on 12-lead electrocardiography
(ECG). Transthoracic echocardiography (TTE) revealed normal
left ventricular size, systolic function (ejection fraction
of 75%), and normal valves and valvular apparatus. Adenosine
stress positron emission tomography (PET) perfusion study of
the heart was done to exclude microvascular angina. Positron
emission tomography study was normal with no evidence of stress-induced
ischaemia. Quantitative sudomotor axon reflex test (QSART) was
normal. The autonomic reflex screen revealed evidence of mild
cardio-vagal impairment with preserved adrenergic and postganglionic
sudomotor responses. Valsalva and tilt test were done. These
showed reduced heart rate responses to deep breathing and to
the Valsalva manoeuvre, persistent tachycardia without orthostatic
hypotension. The patient was diagnosed with a mild form of postural
tachycardia syndrome (POTS). Coronary angiogram showed a dominant
left system with no angiographic evidence of obstructive coronary
artery disease and confirmed bridging of the left anterior descending
artery (LAD) (
Figure 1). A follow-up ECG-gated computed
tomography (CT) angiogram of the heart revealed widely patent
coronary arteries with bridging of the mid-LAD (
Figure 2).
After a failed trial of β-blockers due to intolerance and
side effects, multiple medications have been used with no or
minimal success, including low-dose imipramine, calcium channel
blockers, and nitrates. Only sublingual nitrates were successful
in relieving the patient's chest pain. Given the mild form of
POTS symptoms, the patient was advised to avoid precipitating
factors, and no specific drug treatment was prescribed.
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Figure 1 Cardiac catheterization reveals myocardial bridging of mid-left anterior descending (LAD) coronary artery. Coronary angiograms of mid-LAD coronary artery in diastole (A) and systole (B) show systolic constriction (arrows), which is consistent with myocardial bridging. Normal right coronary artery (RCA) (C). Left main, LM.
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Figure 2 Computed tomography, multiplanar reformation (MPR) image corresponding to A displays segment of mid-left anterior descending coronary artery (thin arrows) partially bridged by myocardium. Volume-rendering image B shows mid-LAD coronary artery (arrow) partially bridged by myocardium (superficial type of intramuscular coronary artery). Aorta, AO; left ventricle, LV.
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Comment
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We describe a case of myocardial bridging and POTS syndrome;
two clinical entities that co-existed. Postural tachycardia
syndrome is characterized by the presence of orthostatic tachycardia
in the absence of orthostatic hypotension with heart rate increase
of
30 bpm. Patients often relate complaints of palpitations,
exercise intolerance, fatigue and near-syncope or syncope and
other non-specific symptoms such as headache and nausea. Symptoms
abate in the supine position.
1
,2 Postural tachycardia syndrome
can occur either primarily or secondary to systemic disease
(
Table 1). Orthostatic intolerance is the main clinical
presentation (
Table 2).
3 Postural tachycardia syndrome
may be of two types: those with autonomic neuropathy (POTS-AN)
and those without (POTS-Alone). Postural tachycardia syndrome-Alone
is diagnosed with head-up tilt test where heart rate is elevated
more than 29 bpm in the first 10 min of the test with no drop
in systolic blood pressure of <20 mmHg and diastolic blood
pressure of 10 mmHg. Postural tachycardia syndrome-AN is usually
diagnosed as POTS-Alone with two of the following: reduced sudomotor
axon reflex test in one site or a second site; reduced Valsalva
response; reduced cardiac response to deep breathing; and/or
distal pattern of anhidrosis on thermoregulatory sweat test.
In our patient, the diagnosis fit the profile of POTS-Alone.
To date, no therapy has been proven to successfully treat all
patients with POTS. In addition, vasodilators, diuretics, and
drugs inhibiting norepinephrine transporter (tricyclic antidepressants)
should be avoided as they aggravate these symptoms. No medicine
is approved by the US Food and Drug Administration for the treatment
of POTS. Most agents are used as ‘off-label’. Moreover,
no pharmacological agent has been tested in a long-term randomized
clinical trial. Some pharmacologic treatments of POTS include
using a low-dose β adrenergic blockers to control heart
rate, vasoconstrictors (midodrine hydrochloride), and others
are central sympatholytic medications (clonidine hydrochloride)
(
Table 3).
4
Myocardial bridging is rare occurring in 0.5–16% in angiographic
studies. The majority of patients with myocardial bridging are
asymptomatic. The usual angiographic finding in myocardial bridging
is systolic narrowing of an epicardial coronary artery. Clinical
presentation is protean and can manifest as atrioventricular
blockade, ventricular tachycardia, myocardial ischaemia, sudden
cardiac death, and myocardial infarction.
5 Therapeutic approaches
include β-blockers (decrease the tachycardia and increase
diastolic time, with a decrease in contractility and compression
of the coronary arteries), and calcium channel blockers by the
same mechanism and to reduce vasoreactivity often associated
with myocardial bridging. Patients who are refractory to medical
therapy can undergo revascularization percutaneously or with
surgical myotomy and/or minimally invasive coronary artery bypass
surgery. These co-existing two clinical entities present a therapeutic
challenge and a pathogenic overlap. Pathogenic overlap such
as tachycardia could worsen the bridge effect in causing myocardial
ischaemia (orthostatic angina), and the presence of a myocardial
bridge could lead to ischaemia and further stress-induced sinus
tachycardia.
Our patient had recurrent anginal pain with no evidence of ischaemia on neither PET study or atherosclerotic disease on angiogram (except for moderate LAD bridging). Since pain was relieved by nitrates (vasodilators) only, the debate in this case is the therapeutic approach. Conflicts in therapeutic decisions may arise when treating patients with POTS disease and symptomatic anginal pain. In this case, the symptomatic LAD bridging responded to medical management. The patient was managed with sublingual nitrates and calcium channel blockers, without aggravating the POTS symptoms (worsen tachycardia), since a low dose was initiated and gradually increased. The fact that the POTS on aggressive testing proved to be mild, allowed the use of the antianginal medications as a first consideration. Had the patient developed intolerable POTS symptoms while on anti-ischaemic drug treatment, coronary stenting of LAD could have been the treatment option before surgical dissection of the bridge.6
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References
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[1] Kanjwal Y, Kosinski D, Grubb BP. The postural tachycardia syndrome: definition, diagnosis and management. Pacing Clin Electrophysiol (2003) 26:1747–57.
[CrossRef][Medline][2] Jáuregui-Renaud K, Hermosillo JA, Jardón JL, Márquez MF, Kostine A, Silva MA, et al. Cerebral blood flow during supine rest and the first minute of head-up tilt in patients with orthostatic intolerance. Europace (2005) 7:460–4.[Abstract/Free Full Text]
[3] Grubb BP, Kanjwal Y, Kosinski DJ. The postural tachycardia syndrome: a concise guide to diagnosis and management. J Cardiovasc Electrophysiol (2006) 17:108–12.[Web of Science][Medline]
[4] Al-Shekhlee A, Lindenberg JR, Hachwi RN, Chelimsky TC. The value of autonomic testing in postural tachycardia syndrome. Clin Auton Res (2005) 15:219–22.[CrossRef][Web of Science][Medline]
[5] Möhlenkamp S, Hort W, Ge J, Erbel R. Update on myocardial bridging. Circulation (2002) 106:2616–22.[Free Full Text]
[6] Alegria JR, Herrmann J, Holmes DR Jr, Lerman A, Rihal CS. Myocardial bridging. Eur Heart J (2005) 26:1159–68.[Abstract/Free Full Text]
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