Discussion
We discussed the case of a middle-aged female with acute respiratory
distress and elevation of blood pressure in the cardiac catheterization
laboratory in favor of FPE.
Acute cardiogenic pulmonary edema is a common and critical condition
caused by increased LV end-diastolic and left atrial (LA) pressures,
which are retrogradely transmitted to the pulmonary venous and the
capillary system. It consequently increases the hydrostatic pressure
across pulmonary capillaries, resulting in fluid accumulation within the
lung interstitium and alveoli.(1) FPE is a
life-threatening and extreme form of cardiogenic pulmonary edema which
develops within minutes. It is related to a sudden rise in cardiac
filling pressures as well as endothelial dysfunction and increased
permeability of pulmonary capillaries, which are the key features to
distinguish FPE from cardiogenic pulmonary edema where we solely have
elevated filling pressures.(2)
Exaggerated sympathetic activity and increased activity of the
renin-angiotensin-aldosterone system (RAAS) are etiologies known to play
essential roles in developing FPE.(2) Catecholamines
increase heart rate and reduce diastolic filling time of the LV, which
notably in patients with diastolic dysfunction results in impaired
diastolic filling and therefore elevation of LA and pulmonary venous
pressures.(4) Both sympathetic hyperactivity and
activation of RAAS caused by catecholamines raise systemic vascular
resistance and precipitate acute elevation of blood pressure. The
augmented afterload results in increased LV wall stress and the
imbalance between oxygen demand and supply, leading to even more
diastolic dysfunction and elevation of filling
pressures.(2) Endothelial dysfunction and excessive
permeability of the pulmonary capillaries are other consequences of
catecholamines.(2, 4) Besides systemic RAAS,
activation of intrapulmonary RAAS contributes to fluid accumulation
within pulmonary interstitial and alveolar areas by increasing pulmonary
capillary permeability.(2)
FPE was reported in some other clinical conditions. Several reports
discussed FPE associated with renal artery stenosis and excessive
renin-angiotensin-aldosterone system activity. Symptoms were improved
after revascularization of the renal artery in these
cases.(5-7) Naman Agrawal et al. in 2016 described
sympathetic crashing acute pulmonary edema as the most severe entity of
acute pulmonary edema, which must be treated with noninvasive
ventilation and intravenous nitrate started in
minutes.(4) In a case report by Catrina PatrĂcio et
al. in 2014, a 64-year-old woman was reported who was admitted to the
emergency department with FPE due to acute severe aortic
insufficiency.(8)
FPE may develop in the cardiac catheterization laboratory at any time
during the procedure. The diagnosis of FPE is based on clinical
evaluation. Rapid progression of dyspnea and hypoxemia indicates the
necessity of prompt diagnosis and management to avoid the need for
mechanical ventilation and adverse outcomes.
It seems that activation of the sympathetic system secondary to extreme
anxiety in combination with severe valvular dysfunction and severe LV
diastolic dysfunction predisposed our patient to FPE.
History and physical examination are the most valuable tools for better
determination of this event.(2) Patients may have a
history of LV diastolic dysfunction, systemic hypertension, or severe
valvular dysfunction. The presence of bilateral renal artery stenosis or
pheochromocytoma must be noted. Moreover, acute events such as
tachyarrhythmias, acute mitral or aortic valve regurgitation, myocardial
ischemia, and hypertensive crisis commonly predispose patients to
FPE.(2, 3) Patients usually present with respiratory
distress, orthopnea, tachypnea, and diaphoresis. Assessment of blood
pressure, heart rate, and oxygen saturation must be done. Elevated blood
pressure, tachycardia, and hypoxemia are common. Auscultation may reveal
rales, S3 gallop, and valvular murmurs. Jugular venous pressure may be
elevated, although it may be hard to measure. 12-lead ECG and bedside
echocardiography are also helpful.(3, 9)
Immediate initiation of high-dose intravenous nitroglycerine must be
done in the first step because of its vasodilatory effect on the
arterial system. The aim is to reduce the afterload and cut the vicious
cycle of sympathetic and RAAS hyperactivity as soon as
possible.(4) Intravenous loop diuretics may also be
helpful. Since FPE is basically caused by fluid redistribution rather
than volume overload, and the diuretic effect of furosemide starts in 30
minutes at the earliest, the effect of loop diuretics is mostly due to
their vasodilator instead of diuretic activity.(2, 4)Supplemental oxygen therapy should be administered for hypoxemia as
well. Once the patient is stabilized, further evaluation and
determination of the cause of FPE must be
performed.(2)