Restrictive cardiomyopathy
Definition
Restrictive cardiomyopathy (RCMP) is characterized by abnormal diastolic function with either thickened or rigid ventricular walls leading to elevated filling pressures of the left- or right-sided cardiac chambers.
Etiology
There is variety of diseases that can cause restrictive cardiomyopathy, including infiltrative diseases, storage diseases and a variety of systemic diseases.
Three of the leading causes of RCMP include cardiac amyloidosis, cardiac sarcoidosis, and cardiac hemochromatosis.
Image 1 Causes of restrictive cardiomyopathy
Pathophysiology
The majority of restrictive cardiomyopathies are caused by infiltration of abnormal matter or substance in between myocytes, storage of abnormal metabolic products within myocytes, or fibrotic injury.
It is characterized by increased stiffness of the myocardium that causes pressure within the ventricle to rise abruptly with only a small increase in volume.
Clinical manifestation
Affecting either or both ventricles, RCMP may cause signs or symptoms of left and/or right heart failure. These are jugular venous distension, ascites, lower extremity edema, and less commonly pulmonary edema.
Syncope occurs occasionally, often exertional, reflecting the limited ability of the heart to increase diastolic filling.
Some patient’s complains are of worse tolerance of exercise or they are newly diagnosed with an arrhythmia most frequently with atrial fibrillation. In the less fortunate cases, some present as sudden cardiac death (SCD).
When we evaluate and physically examine a patient who is suspected of RCM, it is important to look for extracardiac manifestations such as carpal tunnel, which may be present in amyloidosis or bilateral hilar infiltrates seen in sarcoidosis. Hemochromatosis is typically presented with the classic bronze skin, cirrhosis, arthralgias, and sometimes with endocrinopathies as diabetes mellitus from the deposition in pancreas.
Echocardiography findings of restrictive cardiomyopathy
Complete assessment of the Cardiac Amyloidosis is described in our chapter called Amyloidosis.
1. Assessment of left and right ventricular thickness
Both the left and the right ventricle are often thickened, but it is not a requirement.
A usual finding is a small left ventricle (not dilated) with marked atrial dilatation and normal systolic function.
LV wall diameter can be measured from a PLAX or PSAX view.
Relative LV wall thickness - (IVS+PWT)/LVEDD = >0,6 (IVS = interventricular septum, PWT = posterior wall thickness).
Video 1 Restrictive CMP, A3C view - small LV with concentric hypertrophy, sparkling/granular myocardium of the LV and massively dilated LA.
Image 2 Hypertrophy of the LV wall in RKMP, A3C view - concentric hypertrophy especially of the posterior LV wall - 19 mm.
Image 3 Global longitudinal strain assessment in RKMP - significantly reduced GLS -11,7%, hypokinesis of the anterior wall and reduced longitudinal contractility especially in the basal segments - typical apical sparing phenomenon.
Image 4 Mitral annular plane systolic excursion (MAPSE) measurement in RCMP, septal (left) and lateral (right) - MAPSE reflects global longitudinal function of the LV, MAPSE ≥10 mm indicates a preserved ejection fraction <8 mm indicate impaired and <7mm severely impaired left ventricular function. This patient has septal MAPSE 6 mm, and lateral 7 mm.
Video 2 3D assessment of ejection fraction in RKMP with diffuse hypokinesis of LV - moderately reduced EF (41%), but significant systolic dysfunction with cardiac index (CI) = 1,3 l/min/m2.
2. Assessment of the appearance of myocardium
The myocardium appears ‘granular’ or ‘sparkling’ (ground glass) thanks to hyperechogenicity of the myocardial infiltrate.
Video 3 Amyloidosis of the heart, PLAX view - A patient with confirmed AL amyloidosis presenting with typical echocardiographic signs of amyloid infiltration of the myocardium. In the video below you can see the hypertrophic lateral wall and interventricular septum with characteristic granulated or speckled appearance of the myocardium and impaired movement of the basal segments of LV.
Video 4 RCMP, A3C view - dense spontaneous echo contrast of the LV, heavily calcified parts of LV create sparkling appearance of the myocardium
3. Assessment of the left and right atrial volumes
In RCMP the left atrium often enlarges.
Image 5 Extremely dilated LA in RCMP, Simpson’s biplane method in A4C and A2C view - A4C area - 51.0 cm2, A2C - length 99 mm, A2C area - 52.0 cm2, LAVi 160.5 cm3
Video 5 RCMP, dilated LA and RA - LA significantly dilated (LAVi 71.8 cm3/m2) and right atrium (area 33 cm2)
4. Doppler assessment of mitral annular velocities
Mitral annular velocity recorded by Doppler echocardiography is used to evaluate left ventricular diastolic function.
In RCMP PW-Doppler from the mitral valve shows a ‘restrictive pattern’ with very high early diastolic velocity (E-wave), short deceleration time (<160 ms), low late diastolic filling (A-wave) of the transmitral velocity suggesting of impaired left ventricular diastolic function with elevated filling pressures.
Image 6 Doppler signs of RCMP
Image 7 Restrictive cardiomyopathy vs. Constrictive pericarditis: a brief overview
Image 8 PW Doppler measurement of mitral inflow in RKMP, restrictive filling pattern - dominant E wave and small A wave, decreased deceleration time and E/A of 2,06.
Image 9 PW Doppler measurement of mitral inflow in RKMP, restrictive filling pattern - E/A ratio 4,00, E/e’ is 19,5, reduced deceleration time (85 ms).
Image 10 Tissue Doppler septal (left) and lateral (right) in RCMP, Grade IV diastolic dysfunction - Decreased e’ septal - 3cm/s, e’ lateral - 8 cm/s. E/e’ = 19,5
Amyloidosis
Is a disease characterized by extracellular deposition of fibrils that are composed from misfolded products of protein precursors.
Depending on the type of amyloidosis (meaning what type of amyloid is deposited) it can affect different organs and can also involve the heart.
Heart involvement is seen most frequently in the following five types of amyloidosis: amyloid light-chain (AL) amyloidosis, amyloid derived from wild-type transthyretin (TTRwt), mutant TTR (ATTRm, or familial amyloidosis), localized atrial amyloid deposits derived from atrial natriuretic peptide and rarely the secondary (AA) amyloidosis (derived from the inflammatory protein serum amyloid A).
Nearly all cases of clinical cardiac amyloidosis (>95%) are caused by light chain amyloidosis (AL) and transthyretin amyloidosis (ATTR) as the localized atrial amyloid deposits derived from atrial natriuretic peptide have no effect on survival and no treatment needed.
The most common manifestation of cardiac amyloidosis is heart failure as a result of restrictive cardiomyopathy.
Image 11 Amyloidosis subtypes that affect the heart
Adopted from: Garcia-Pavia P, Rapezzi C, Adler Y, et al. Diagnosis and treatment of cardiac amyloidosis: a position statement of the ESC Working Group on Myocardial and Pericardial Diseases. Eur Heart J. 2021 Apr 21;42(16):1554-1568. doi: 10.1093/eurheartj/ehab072.
AL Amyloidosis
The precursor protein of AL amyloidosis is an abnormal light chain produced by dysfunctional plasma cells.
AL amyloidosis is associated with multiple myeloma and the diagnosis and management requires a multidisciplinary approach.
AL amyloidosis can affect almost any organ with the exception of the central nervous system.
Usual age at onset is >50 and it is a rare condition with an incidence of approximately 2,500 to 5,000 new cases in the USA per year.
ATTR Amyloidosis
ATTR amyloidosis can be either hereditary or acquired disease.
Hereditary ATTR amyloidosis is caused by a genetic mutation in the gene encoding transthyretin.
Transthyretin’s main physiological function is to transport the thyroid hormone as well as vitamin A (retinol). However, ATTR amyloidosis is not been proven to be associated with thyroid or vitamin A pathologies.
Wild-type (non-hereditary) ATTR amyloidosis typically affects elderly men and presents with cardiac symptoms.
It is the most common cardiac amyloidosis.
The prevalence of wild type ATTR amyloidosis increases with age with nearly all patients being >60 years of age.
Clinical presentation and diagnosis
Cardiac amyloidosis typically presents with heart failure symptoms and signs with prominent features of right ventricular failure including:
- lower extremity edema
- jugular vein distention
- hepatic congestion and ascites
- dyspnoea
In addition, if the conduction system is affected, patients may present with syncope or pre-syncope. In different types of amyloidosis, distinct extracardiac symptoms can be present. Extracardiac features are summmarised in the table below.
Image 12 Clinical manifestation of AL and ATTR amyloidosis
Adopted from: Georgios Papingiotis; Lamprini Basmpana, Dimitrios Farmakis, Cardiac amyloidosis: epidemiology, diagnosis and therapy, e-Journal of Cardiology Practice, Vol. 19, N° 19 - 21 Apr 2021, available from: https://www.escardio.org/Journals/E-Journal-of-Cardiology-Practice/Volume-19/cardiac-amyloidosis-epidemiology-diagnosis-and-therapy
ECG
ECG features of AL amyloidosis include:
- Low-voltage in limb leads
- rightward axis
- 1st degree AV block
- Q waves seen in leads V1 to V3
- Left bundle branch block is rare in AL amyloidosis
In ATTR amyloidosis:
- Normal voltage
- Nonspecific conduction disturbance
- ST-T wave changes
- Left bundle branch block is more common
- Particularly in ATTRwt, high-degree AV block may occur as the disease progresses
Echocardiography
A list of possible findings on transthoracic echocardiography of amyloidosos includes:
- Thickening of the left ventricle.
- Granular or sparkling appearance of the myocardium secondary to amyloid deposition in the myocardium.
- Thickening of interventricular septum
- Diastolic dysfunction
- Normal or reduced LV cavity
- Pericardial effusion (usually small)
- Right ventricular hypertrophy
- Left atrial enlargement
- Thickened AV valves
- Right ventricular dilatation (indicates poor prognosis)
- Dynamic left ventricular outflow tract obstruction
- Dissociation between short and long axis systolic function.
- Intracardiac thrombus as a result of poor LV function and especially if atrial fibrillation is present
The echocardiographic diagnostic criteria proposed by the ESC from (Image 13):
Adopted from: Garcia-Pavia P, Rapezzi C, Adler Y, et al. Diagnosis and treatment of cardiac amyloidosis: a position statement of the ESC Working Group on Myocardial and Pericardial Diseases. Eur Heart J. 2021 Apr 21;42(16):1554-1568. doi: 10.1093/eurheartj/ehab072. PMID: 33825853; PMCID: PMC8060056.
A typical echocardiographical finding for cardiac amyloidosis is an increased thickness of the left ventricle wall (>12 mm).
Other findings such as left atrial enlargement can often be appreciated but as well as the increased wall thickness, they are not specific for cardiac amyloidosis. and the differential diagnosis includes hypertension, flow obstruction in aortic stenosis or hypertrophic cardiomyopathy and others.
In terms of function of the ventricles, a diastolic dysfunction is usually found. Diastolic dysfunction can begin early in the course of the disease (especially in terms of E/e′ ratio ) and gradually worsens with the progression of the disease.
More specific is the speckled pattern (of the myocardium) appearing because of different echogenicity between the amyloid deposits and the myocardium.
Additionally, a specific global longitudinal strain (GLS) pattern is a sensitive and specific finding for cardiac amyloidosis. The GLS typically decreases earlier than the LVEF which results in a GLS-LVEF dissociation. Consequently, a LVEF:GLS ration can be calculated and used to differentiate cardiac amyloidosis from other pathologies with similar appearance.
The GLS pattern also has a typical apical sparing pattern.
Video 6 Amyloidosis of the heart, PLAX view - A patient with confirmed AL amyloidosis presenting with typical echocardiographic signs of amyloid infiltration of the myocardium. In the video below you can see the hypertrophic lateral wall and interventricular septum with characteristic granulated or speckled appearance of the myocardium and impaired movement of the basal segments of LV.
Image 14 Granulated character of IVS myocardium secondary to amyloid deposition, PLAX view. This is caused by hyperechogenicity of the amyloid deposits compared to the adjacent myocardium.
Image 15 Planar diameters of the left ventricle, PLAX view - note the concentric hypertrophy of the left ventricle, which is not dilated at EDD 44mm, but has hypertrophic septum (13mm) and lateral wall (12mm). The speckled character of the myocardium is also apparent.
Video 7 AL amyloidosis, Apical four chamber view - granulated myocardium, thickened LV walls and reduced mobility of the basal segments.
Video 8 Another patient with confirmed AL amyloidosis, PLAX view- concentric hypertrophy of the LV with preserved ejection fraction and no apparent regional movement impairment.
Video 9 TTR amyloidosis, A4C view - advanced form of amyloidosis with granulated sparkling of the myocardium, the LV has concentric hypertrophy with IVS diameter 14 mm. Also note the hypokinesis of basal segments (apical sparing).
Image 16 PW Doppler measurement of mitral inflow in a patient with amyloidosis - note the restrictive pattern of the mitral inflow signal with dominant E wave and E/A ratio of 4,17 revealing a severe diastolic dysfunction (Grade III-IV) caused by the amyloid infiltration of the myocardium.
Image 17 Grading of diastolic dysfunction based on the mitral inflow signal summary
Image 18 Septal (left side) and lateral (right side) mitral annular peak early diastolic velocity (e′)- note the reduced velocities of the s’, e’ and a’ waves that are below 5 cm/s. The E/e’ ratio of 28.9 is highly suggestive of increased filling pressures in accordance with the diastolic dysfunction.
Image 19 Tricuspid annular plane systolic excursion (TAPSE) measured in M mode, AL amyloidosis, A4C view - note the reduced systolic excursion to 14 cm, also a sign of impaired movement of the basal segments secondary to amyloidosis.
Image 20 Global longitudinal strain (GLS) measurement in a patient with amyloidosis - typical strain pattern for amyloidosis is shown with apical sparing, best seen in the bulls-eye diagram. Reduced longitudinal contraction in basal segments - GLS 7%.
Image 21 Global longitudinal strain (GLS) measurement, AL amyloidosis - “apical sparing” pattern, GLS -11%.
Cardiac magnetic resonance (CMR)
The CMR can be highly suggestive of cardiac amyloidosis, but it cannot be used to make the final diagnosis.
It should be used when there is a clinical suspicion an infiltrative process, hypertrophic cardiomyopathy, constrictive pericarditis or myocarditis could be the cause of the increased wall thickness.
Additionally, CMR cannot distinguish different types of amyloid and other diagnostic methods must be used (see below).
CMR findings suggestive of cardiac amyloidosis include biventricular and atrial septal thickening and normal ventricular cavity size.
Late gadolinium enhancement typically reveals diffuse or patchy subendocardial enhancement, which often involves the atrium as well as increase in extracellular volume with T1 mapping.
The ESC diagnostic criteria are summarised below, (Image 22)
Garcia-Pavia P, Rapezzi C, Adler Y, et al. Diagnosis and treatment of cardiac amyloidosis: a position statement of the ESC Working Group on Myocardial and Pericardial Diseases. Eur Heart J. 2021 Apr 21;42(16):1554-1568. doi: 10.1093/eurheartj/ehab072. PMID: 33825853; PMCID: PMC8060056.
Laboratory testing
Routine laboratory testing may reveal involvement of different organs for example abnormal liver tests - liver involvement or abnormal kidney tests - kidney involvement.
Natriuretic peptides (BNP, NT-proBNP) or cardiac troponins are elevated when the heart is involved.
To diagnose AL amyloidosis, assessment of the presence of light chains is needed.
The tests that are recommended to be performed include: serum free light chain concentration, serum and urine immunofixation electrophoresis (IFE) and serum kappa/lamda free light chain ratio analysis.
The AL amyloidosis should be ruled out before performing nuclear imaging tests for ATTR diagnosis confirmation.
Nuclear Imaging
Nuclear imaging plays a key role in the confirmation of ATTR amyloidosis. A bone tracer scintigraphy is used to assess cardiac uptake of technetium (PYP, DPD or HMDP, depending mainly on availability). A positive test is defined as grade 2 or 3 uptake or H/CL ratio >1.5. If the nuclear imaging test is available, it avoids the need to perform a cardiac biopsy and is now the preferred method due to its lower risk for the patient.
Endomyocardial biopsy
Endomyocardial biopsy (EMB) was a standard method for confirmation of cardiac amyloid diagnosis. However, with the advancements of non-invasive testing its role has diminished. It may be considered in patients with inconclusive results from previous tests or when there are doubts about the diagnosis of cardiac amyloidosis. In standard cases, the EMB can be avoided.
Image 23 Amyloidosis diagnosis
AL indicates immunoglobulin light chain; ATTRv, cardiac variant transthyretin amyloidosis; ATTRwt, wild-type transthyretin amyloidosis; CMR, cardiac magnetic resonance; H/CL, heart/contralateral chest ratio; HCM, hypertrophic cardiomyopathy; and IFE, immunofixation electrophoresis.
Kittleson MM, Maurer MS, Ambardekar AV, et al. American Heart Association Heart Failure and Transplantation Committee of the Council on Clinical Cardiology. Cardiac Amyloidosis: Evolving Diagnosis and Management: A Scientific Statement From the American Heart Association. Circulation. 2020 Jul 7;142(1):e7-e22. doi: 10.1161/CIR.0000000000000792. Epub 2020 Jun 1. Erratum in: Circulation. 2021 Jul 6;144(1):e11. PMID: 32476490.
Therapy
There are two possible groups of therapies for cardiac amyloidosis. First is managing the heart failure and second is treatment of the amyloidosis itself, if possible.
Heart failure management
Standard heart failure medical therapy can be used to treat cardiac amyloidosis induced heart failure. However, patients may not tolerate hypotension which results from the use of angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, angiotensin receptor neprilysin inhibitors, beta-blockers and mineralocorticoid receptor antagonists. Loop diuretics are usually prescribed.
Antiarrhythmic treatment
There is currently a lack of data concerning antiarrhythmic treatment in patients with cardiac amyloidosis. Several distinct features of these patients are the following. When atrial dysfunction is suspected based on imaging methods, patients may benefit from anticoagulation therapy, even in the absence of atrial fibrillation/flutter. A problematic area is the use of implantable cardioverter-defibrillators (ICDs) as patients may not benefit from the implantation. This is because a common cause of cardiac arrest in these patients is a non-shockable rhythm. The use of ICDs should be considered in patients with documented ventricular arrhythmias. However, there are no definitive data to support a clear recommendation.
Heart transplantation
Heart transplantation represents a possible therapeutic option, however there are many limitations to its use. That is because amyloidosis is often a multiorgan disease and the amyloidogenic protein also has a source, which is always outside of the heart. A careful selection of patients needs to be performed. In AL amyloidosis, the heart transplantation needs to be combined with the treatment of the underlying condition, which includes chemotherapy. In ATTRm amyloidosis, the source is located in the liver and thus, the only viable option is a combined heart and liver transplantation. In ATTRwt amyloidosis, the heart transplantation is usually not indicated, as it typically affects older patients who do not meet the age criteria for it.
Specific therapy for AL amyloidosis
Treatment of AL amyloidosis is performed by a hematologist. Two main therapeutic options exist: chemotherapy and/or autologous stem cell transplantation.
Specific therapy for ATTR amyloidosis
Apart from liver or combined heart-liver transplantation for the treatment of hereditary ATTR mentioned above, new options have emerged for the treatment of ATTRwt. Tafamidis is suitable for patients with ATTR cardiomyopathy with heart failure classified as New York Heart Association Class I to III.
Tafamidis acts as a transthyretin stabilizer and reduces the formation of amyloid. Tafamidis reduces mortality and cardiovascular-related hospitalisations, improves quality of life and reduced declines in functional capacity. Other drugs have been approved by the FDA for use in patients with amyloidosis induced neuropathy.
Sarcoidosis
Sarcoidosis is an inflammatory granulomatous disease that can affect any organ.
Up to one-quarter of patients with systemic sarcoidosis may have evidence of cardiac involvement.
Inflammatory process results in scarring, most commonly affecting the interventricular septum, posterior left ventricle, right ventricle, and anterior left ventricle.
The clinical manifestations of cardiac sarcoidosis include heart block, atrial arrhythmias, ventricular arrhythmias and heart failure.
Echocardiography findings - thinning of the basal IVS or LV free wall, wall aneurysms, wall motion abnormalities and diastolic dysfunction are typical patterns of cardiac sarcoidosis.
Cardiac MR - late gadolinium enhancement typically present in mid-wall and/or epicardial, sparing subendocardium (basal heart, particularly septum and lateral
wall)
F18 FDG-PET - is useful for detection and treatment response.
Definitive diagnosis requires pathology confirmation of noncaseating granuloma by endomyocardial biopsy, although sensitivity is poor.
Immunosuppression with corticosteroids remains the standard therapy for the acute inflammatory phase of CS.
Video 10 Sarcoidosis of the heart with aneurysm of the basal part of inferoseptal wall, modified A4C view - note the marked hypokinesis of the inferoseptal wall and basal parts of lateral wall. The LV is not dilated with estimated EF 50%.
Image 24 Sarcoidosis, diameter of the inferoseptal aneurysm - 28 x 14 mm
Video 11 Sarcoidosis of the heart with aneurysm of the basal part of inferoseptal wall, PSAX view
Video 12 Sarcoidosis of the heart with aneurysm of the basal part of inferoseptal wall, A4C view - note the hypokinetic movement of the basal parts.
Image 25 Global longitudinal strain assessment in sarcoidosis - GLS lowered to -14,5%, marked hypokinesis of the basal parts of the inferoseptal wall (aneurysm).
Video 13 Cardiac sarcoidosis, A4C view - moderately dilated LV with LVEF 45-50% and aneurysm of the basal ⅓ of the interventricular septum. The affected parts are akinetic to dyskinetic.
Video 14 Cardiac sarcoidosis, PLAX view - aneurysm of the interventricular septum.
Hemochromatosis
Cardiac hemochromatosis or primary iron-overload cardiomyopathy is an important and potentially preventable cause of heart failure.
Iron-overload syndromes may be hereditary or acquired.
This is initially characterized by diastolic dysfunction or arrhythmias - deposition of iron may occur in the entire cardiac conduction system, especially the atrioventricular node (complete atrioventricular block may need implacement of a permanent pacemaker).
Paroxysmal atrial fibrillation is the most common arrhythmia observed in patients with cardiac hemochromatosis. The prevalence of ventricular arrhythmias increases with left ventricular dilation and low LVEF.
In later stages disease can progress to dilated cardiomyopathy.
Therapy of iron-overload states is important to prevent or reverse cardiac dysfunction. Removal of excess iron from the tissues in these patients minimizes generation of free radicals, reducing organ damage.
Therapy to remove excess iron stores includes therapeutic phlebotomy and iron-chelating agents.
Dietary management are also important in managing cardiac hemochromatosis.
Congestive heart failure should be managed with standard medical therapy for heart failure.
Video 15 Hereditary hemochromatosis causing HFrEF, PLAX view - hemochromatosis causing diffuse hypokinesis, apex and inferior wall are almost akinetic, biplane EF 16%. LA is severely dilated (LAVi 75.4 cm3/m2).
Video 16 Hereditary hemochromatosis causing HFrEF, PSAX view
Video 17 Hereditary hemochromatosis causing HFrEF, A3C view - diffuse hypokinesis to akinesis, EF 16%.
Video 18 Hereditary hemochromatosis causing HFrEF after treatment (2 year follow up), PLAX view- normalization of the size and function of the LV (EF 55-60%), no significant regional wall movement abnormality.
Video 19 Hereditary hemochromatosis causing HFrEF after treatment (2 year follow up), A4C view- normalization of the size and function of the LV (EF 55-60%), no significant regional wall movement abnormality.
References
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- Georgios Papingiotis; Lamprini Basmpana, Dimitrios Farmakis, Cardiac amyloidosis: epidemiology, diagnosis and therapy, e-Journal of Cardiology Practice, Vol. 19, N° 19 - 21 Apr 2021, available from: https://www.escardio.org/Journals/E-Journal-of-Cardiology-Practice/Volume-19/cardiac-amyloidosis-epidemiology-diagnosis-and-therapy
- Kittleson MM, Maurer MS, Ambardekar AV, Bullock-Palmer RP, Chang PP, Eisen HJ, Nair AP, Nativi-Nicolau J, Ruberg FL; American Heart Association Heart Failure and Transplantation Committee of the Council on Clinical Cardiology. Cardiac Amyloidosis: Evolving Diagnosis and Management: A Scientific Statement From the American Heart Association. Circulation. 2020 Jul 7;142(1):e7-e22. doi: 10.1161/CIR.0000000000000792. Epub 2020 Jun 1. Erratum in: Circulation. 2021 Jul 6;144(1):e11. PMID: 32476490.
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