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Cardiac magnetic resonance imaging findings in a patient with noncompaction of ventricular myocardium
Clinical Imaging 32 (2008) 223 – 226
Cardiac magnetic resonance imaging findings in a patient with noncompaction of ventricular myocardium Xin Liu, Aya Kino, Chris Francois, David Tuite, Karin Dill, James C. Carr⁎ Department of Radiology, Northwestern University Medical School, Chicago, IL 60611, USA Received 5 July 2007; accepted 5 September 2007
Abstract Noncompaction of ventricular myocardium (NCVM) is a rare cardiomyopathy characterized by numerous prominent trabeculations in the ventricular wall and deep intertrabecular recesses communicating with the ventricular cavity. This article reports a 33-year-old female with a familial history of cardiovascular disease, who presented with shortness of breath and palpitations. Transesophageal echocardiography and cardiac magnetic resonance imaging (MRI) were consistent with the diagnosis of NCVM. The advantages of MRI in depicting both the morphological features and pathological characteristics of NCVM were presented. © 2008 Elsevier Inc. All rights reserved. Keywords: Magnetic resonance imaging; Noncompaction; Cardiomyopathy
1. Introduction NCVM is a rare form of cardiomyopathy which is categorized as unclassified cardiomyopathy by the World Health Organization [1]. It is morphologically characterized by numerous prominent trabeculations in the ventricular wall and deep intertrabecular recesses communicating with the ventricular lumen. NCVM can be found as a feature of several malformation syndromes as well as in isolation. An intrauterine arrest of the normal myocardial compaction process is the assumed mechanistic basis [2]. The incidence of NCVM is sporadic, but it may have a genetic origin in some patients who have chromosomal abnormalities [3,4]. The diagnosis of NCVM has important clinical implications due to its possible association with some severe complications such as progressive left ventricle dysfunction, the risk of systemic embolism, and malignant arrhythmias [5]. Echocardiography has been widely used for the diagnosis of NCVM and some diagnostic criteria have been proposed ⁎ Corresponding author. 448 East Ontario Street, Suite 700, Chicago, IL 60611, USA. Tel.: +1 312 695 4218; fax: +1 312 926 5991. E-mail address: [email protected] (J.C. Carr). 0899-7071/08/$ – see front matter © 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.clinimag.2007.09.009
[6–8]. Cardiac MRI is an excellent alternative modality for noninvasive assessment of patients with NCVM because it has several advantages, such as high spatial resolution, large field of view, and ability to detect thrombus and myocardial scar. In this case report, we describe MRI features of a patient with NCVM whose diagnosis was supported by echocardiography and clinical findings. 2. Case report A 33-year-old woman presented with shortness of breath and palpitations and had a history of heart failure for a number of years, particularly after the birth of her last child 7 years ago. She had a history of cardiac surgery at 5 years of age for what was described as a fibrous material over her pericardium. There was no record of a diagnosis of noncompaction at that time. Her mother died at 19 years of age from heart disease (specific type of the disease is unknown). Her uncle, maternal grandmother, and maternal grandfather had a similar heart disease, and her uncle refused a heart transplant. Upon admission, her stress test electrocardiogram demonstrated normal sinus rhythm. Blood studies showed normal results.
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Contrast-enhanced cardiac MRI was performed on a 1.5-T clinical scanner (Avanto, Siemens, Erlangen, Germany) with a phase-array coil incorporating the Siemens total image matrix technology. Cardiac magnetic resonance cine was performed with a breathhold steady-state free precession (SSFP) sequence. Twenty-five phases were acquired per cardiac cycle, with
spatial resolution of 2.4×1.8×6.0 mm. Cines were obtained in vertical long-axis, four-chamber, left ventricular outflow tract and short-axis views. Cine images showed numerous abnormal trabeculations in the left anterior, apical, and inferior left ventricular wall, as well as the right ventricular wall, though to a lesser extent (Fig. 1A). In the short-axis view of the left ventricle, the ratio of noncompacted to
Fig. 1. Four-chamber (A) and short-axial (B) MRI cine image showed trabecular meshwork and deep intertrabecular recesses in left ventricular wall (arrow) and right ventricular wall (arrowhead). The ratio of the thickness of trabeculated myocardium and nontrabeculated myocardium of left ventricle was 3.8 at enddiastole. (C) Four-chamber MRI cine image showed an aneurysm (1.5×1.3 cm2) in the inferior right ventricular free wall at the apex at the end of systole (arrow). (D and E) Dynamic MRA demonstrated the structure of trabeculations more clearly, especially in the right ventricular wall (arrow). It also confirmed that the intertrabecular recesses were communicated with ventricular cavity. (F) Delayed-enhancement MRI showed a linear enhancement in the mid myocardium of basal septum suggesting scar (arrow). (G and H) TEE revealed significant trabeculations in the left ventricular apex and mid cavity (arrow), consistent with the findings of MRI.
X. Liu et al. / Clinical Imaging 32 (2008) 223–226
compacted myocardial layers (NC/C ratio) at the site of maximal wall thickness was 3.8 at end-diastole (Fig. 1B). A focal outpouching was detected in the inferior right ventricular free wall at the apex, suggesting a right ventricular aneurysm (Fig. 1C). There was impaired left ventricular systolic function (ejection fraction 37%) with severe akinesis and flattening of the septal wall. In addition, mild mitral regurgitation and moderate tricuspid regurgitation were demonstrated. Dynamic magnetic resonance angiography (MRA) was performed using single shot inversion recovery SSFP in a four-chamber view. The acquisition time per image was 250 msec. ECG-gating was utilized with the acquisition period occurring at end diastole. A total of 6 ml (0.2 mmol/kg) of Gadolinium-DTPA (Magnevist, Berlex Laboratories, NJ, USA) was injected at rate of 4 ml/s via a peripherally placed intravenous cannula. Noncompacted myocardium from both ventricles was more clearly visible on dynamic MRA images (Fig. 1D and E). In addition, a hypoperfusion was detected in the noncompacted myocardium in resting dynamic MRA images. Delayed-enhancement MRI was performed using inversion recovery turboFLASH sequence with magnitude and phase sensitive reconstruction 10 min after contrast administration in ventricular long-axis, four-chamber, threechamber, and short-axis views. A linear area of enhancement was present within the mid myocardium of the basal septum suggesting a scar (Fig. 1F). There was no evidence of intracardiac thrombus. Transesophageal echocardiography (TEE) revealed normal left ventricular size with significant trabeculations of the left ventricular apex and mid cavity (Fig. 1G and H). The NC/C ratio at end-systole was 3.5. Severe septal hypokinesis with global hypokinesis and severe systolic dysfunction were noted. The overall left ventricular ejection fraction was about 25%. In addition to a dilated and dysfunctional right ventricle, an akinetic apical segment of the right ventricular apex, possibly representing an apical aneurysm, was also detected. Trivial pericardial effusion was noted. Color Doppler flow revealed mild to moderate mitral regurgitation and moderate tricuspid regurgitation with moderate pulmonary hypertension.
3. Discussion In this case report, we describe the MRI findings in biventricular NCVM. Although NCVM more commonly affects the left ventricle, right ventricular involvement has also been described [5,7,9,10]. Additionally, we describe the utility of dynamic MRA and delayed enhanced imaging for better characterization of the left ventricular myocardium. Different definitions of NCVM by echocardiography have been proposed in previous studies [6–8]. Although these diagnostic echocardiographic criteria for NCVM are not uniform and not fully accepted in clinical practice, three
225
echocardiographic criteria were frequently used in the previous studies [5,7,11,12]: (1) numerous prominent trabeculations and deep intertrabecular recesses in the ventricular wall, (2), communication of the intertrabecular recesses with the ventricular cavity, and (3) an end-systolic NC/C ratio N2.0. The TEE findings in our case were consistent with these criteria. The end-systolic NC/C ratio was greater than 2.0, and most of the noncompacted segments are hypokinetic. In addition, color Doppler demonstrated flow in the intertrabecular recesses, suggesting the communication of intertrabecular recesses with ventricular cavity. Ritter et al. [9] and Burke et al. [10] reported that right ventricular noncompaction was involved in 41% (7/17) and 43% (6/14) of patients with NCVM, respectively. Because of the heavily trabeculated nature of the normal right ventricular apex, it is difficult to distinguish pathological trabeculations from the variants of normal patterns. To date, there are no diagnostic criteria that have been proposed in echocardiography of noncompaction of the right ventricle [5,7,9], or the diagnosis has been assessed on a purely qualitative basis [9]. However, based on pathohistologic study, Burke et al. [10] proposed a histological criteria for right ventricular noncompaction: transmural thickness of the noncompacted right ventricle greater than 75%. In our case, the diagnosis for right ventricle was established by qualitative assessment. Cardiac MRI with its superior spatial resolution and higher contrast between blood and myocardium is better suited to evaluating abnormalities of the ventricular myocardium than traditional echocardiography. Petersen et al. [3], based on a modified criteria (end-diastolic NC/C ratio N2.3), demonstrated that the sensitivity and specificity of MRI cine imaging for detecting NCVM were 86% and 99%, respectively. In addition, Korcyk et al. [13] proposed that trabecular mass of greater than 20% of total myocardial mass could be a more useful index for the diagnosis of NCVM. In our case, the end-diastolic NC/C ratio with MRI was 3.8, thus making a diagnosis based on echo criteria. Because noncompacted myocardium also exists in healthy, dilated, and hypertrophied hearts [3,5,11], when increasing diagnostic specificity for distinguishing pathological trabeculations, the measurement of NC/C ratio by MRI was determined at end-diastole; however, the echocardiographic values were taken at end-systole. MRI allows the best visual differentiation of the two layers at end-diastole due to its high spatial resolution. Cardiac MRI is not only useful for detecting the presence of abnormally trabeculated myocardium but may also demonstrate the extent and distribution of the abnormality. This is particularly beneficial when trabeculations are confined to the ventricular apex [3,5] or right ventricle, regions that are difficult to image by echocardiography. Previous studies performed by Jenni [7] and Oechslin [5] demonstrated that the typical distribution of prominent trabeculations in patients with NCVM were the left
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X. Liu et al. / Clinical Imaging 32 (2008) 223–226
ventricular apical, lateral, and inferior segments. Meanwhile, these studies suggested that the assessment of prominent trabeculation distribution is useful for differentiating pathological trabeculations from the prominent trabeculations found in normal or hypertrophied hearts. Another study by Petersen et al. [3] also showed that noncompactions were predominantly localized in the left ventricular apical and mid-cavity (lateral and inferior) wall, but there were no differences between the distribution of noncompactions found in healthy, dilated, and hypertrophied hearts compared to patients with NCVM. Injection of contrast may help to further characterize the noncompacted myocardium. In this case report, MRA imaging more clearly demonstrated the trabeculations and also confirmed communication between the trabecular recesses and the ventricular cavity. Our study also showed resting hypoperfusion in the noncompacted muscle, a finding that has been described in previous studies [13,14]. Moreover, dynamic MRA may identify ventricular thrombus in the deep recesses between the trabeculations. There was no evidence of intracardiac thrombus in this study. Pathohistologic studies have demonstrated that ischemic lesions such as necrosis, fibrosis, and scar were associated with abnormalities of the myocardial microcirculation [7] and were widely distributed in the endocardial (nonecompacted) layer and subendocardial area [5,7,10]. Impaired microperfusion and subsequent scar tissue formation were believed to be associated with left ventricle dysfunction and lethal ventricular arrhythmias [5,7,15]. Jassal et al. [15] reported that delayed-enhanced cardiac MRI showed atypical scar within the abnormal trabeculations. In this case, we did not find the evidence of fibrosis within the trabeculations, but a linear scar was found in the basal septum. This may be related to the abnormal myocardial microcirculation in patients with NCVM. According to the pathohistologic study, myocardial fibrosis and scar may be present in the adjacent area of noncompaction or the area of compacted myocardium [7,10]. Ventricular aneurysm associated with NCVM was only previously reported in one case with a left ventricular aneurysm [4]. But in this case, the ventricular aneurysm was located in the right ventricle. Ventricular aneurysm associated with NCVM is thought to be caused by regional ventricular wall thinning and myocardial hypoperfusion due to abnormalities of the myocardial microcirculation in patients with NCVM [14]. The major clinical complications of NCVM are heart failure, atrial and ventricular arrhythmias, and thromboembolic events [5,6,16]. Heart failure is the most frequent event in hospital admission, and the prognosis of symptomatic patients is poor [5,16]. There is no specific treatment option for NCVM. Medical management varies with clinical manifestation, left ventricular ejection fraction, and presence or absence of arrhythmias. Oral anticoagulation is recom-
mended for NCVM with left ventricular systolic dysfunction, atrial arrhythmia, and local thrombi due to the increased risk of systemic embolism [5,17]. Heart transplantation should be considered for patients who have endstage heart failure. In conclusion, contrast-enhanced cardiac MRI demonstrates not only the morphological features of NCVM but also myocardial perfusion abnormalities and myocardial scar which represent severe complications of NCVM. References [1] Richard P, McKenna W, Bristow M, et al. Report of the 1995 World Health Organization/International Society and Federation of Cardiology Task Force on the definition and classification of cardiomyopathies. Circulation 1996;93:273–83. [2] Sedmera D, Pexieder T, Vuillemin M, et al. Developmental patterning of the myocardium. Anat Rec 2000;258:319–37. [3] Petersen SE, Selvanayagam JB, Wiesmann F, et al. Left ventricular noncompaction: insights from cardiovascular magnetic resonance imaging. J Am Coll Cardiol 2005;46:101–5. [4] Sasse-Klaassen S, Probst S, Gerull B, et al. Novel gene locus for autosomal dominant left ventricular noncompaction maps to chromosome 11p15. Circulation 2004;109:2720–3. [5] Oechslin EN, Attenhofer C, Jost H, Rojis JR, et al. Long-term followup of 34 adults with isolated left ventricular noncompaction: a distinct cardiomyopathy with poor prognosis. J Am Coll Cardiol 2000;36:493–500. [6] Chin TK, Perloff JK, Williams RG, et al. Isolated noncompaction of left ventricular myocardium. A study of eight cases. Circulation 1990;82:507–13. [7] Jenni R, Oechlin E, Schneider J, et al. Echocardiographic and pathoanatomical characteristics of isolated left ventricular noncompaction: a step towards classification as a distinct cardiomyopathy. Heart 2001;86:666–71. [8] Stöllberger C, Finsterer J. Left ventricular hypertrabeculation/noncompaction. J Am Soc Echocardiogr 2004;17:91–100. [9] Ritter M, Oechslin E, Sutsch G, Attenhofer C, Schneider J, Jenni R. Isolated noncompaction of the myocardium in adults. Mayo Clin Proc 1997;72:26–31. [10] Burke A, Mont E, Kutys R, et al. Left ventricular noncompaction: a pathological study of 14 cases. Hum Pathol 2005;36:403–11. [11] Biagini E, Ragni L, Ferlito M, et al. Different types of cardiomyopathy associated with isolated ventricular noncompaction. Am J Cardiol 2006;98:821–4. [12] Frischknecht BS, Jost CHA, Oechslin EN, et al. Validation of noncompaction criteria in dilated cardiomyopathy, and valvular and hypertensive heart disease. J Am Soc Echocardiogr 2005;18:865–72. [13] Korcyk D, Edwards CC, Armstrong G, et al. Contrast-enhanced cardiac magnetic resonance in a patient with familial isolated ventricular noncompaction. J Cardiovasc Magn Reson 2004;6:569–76. [14] Sato Y, Matsumoto N, Yoda S, et al. Left ventricular aneurysm associated with isolated noncompaction of the ventricular myocardium. Heart Vessels 2006;21:192–4. [15] Jassal DS, Nomura CH, Ncilan TG, et al. Delayed enhancement cardiac MR imaging in noncompaction of left ventricular myocardium. J Cardiovasc Magn Reson 2006;8:489–91. [16] Murphy RT, Thaman R, Blanes JG, et al. Natural history and familial characteristics of isolated left ventricular non-compaction. Eur Heart J 2005;26:187–92. [17] Stöllberger C, Finsterer J. Left ventricular hypertrabeculation/noncompaction and stroke or embolism. Cardiology 2005;103:68–72.
Cardiac magnetic resonance imaging findings in a patient with noncompaction of ventricular myocardium Xin Liu, Aya Kino, Chris Francois, David Tuite, Karin Dill, James C. Carr⁎ Department of Radiology, Northwestern University Medical School, Chicago, IL 60611, USA Received 5 July 2007; accepted 5 September 2007
Abstract Noncompaction of ventricular myocardium (NCVM) is a rare cardiomyopathy characterized by numerous prominent trabeculations in the ventricular wall and deep intertrabecular recesses communicating with the ventricular cavity. This article reports a 33-year-old female with a familial history of cardiovascular disease, who presented with shortness of breath and palpitations. Transesophageal echocardiography and cardiac magnetic resonance imaging (MRI) were consistent with the diagnosis of NCVM. The advantages of MRI in depicting both the morphological features and pathological characteristics of NCVM were presented. © 2008 Elsevier Inc. All rights reserved. Keywords: Magnetic resonance imaging; Noncompaction; Cardiomyopathy
1. Introduction NCVM is a rare form of cardiomyopathy which is categorized as unclassified cardiomyopathy by the World Health Organization [1]. It is morphologically characterized by numerous prominent trabeculations in the ventricular wall and deep intertrabecular recesses communicating with the ventricular lumen. NCVM can be found as a feature of several malformation syndromes as well as in isolation. An intrauterine arrest of the normal myocardial compaction process is the assumed mechanistic basis [2]. The incidence of NCVM is sporadic, but it may have a genetic origin in some patients who have chromosomal abnormalities [3,4]. The diagnosis of NCVM has important clinical implications due to its possible association with some severe complications such as progressive left ventricle dysfunction, the risk of systemic embolism, and malignant arrhythmias [5]. Echocardiography has been widely used for the diagnosis of NCVM and some diagnostic criteria have been proposed ⁎ Corresponding author. 448 East Ontario Street, Suite 700, Chicago, IL 60611, USA. Tel.: +1 312 695 4218; fax: +1 312 926 5991. E-mail address: [email protected] (J.C. Carr). 0899-7071/08/$ – see front matter © 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.clinimag.2007.09.009
[6–8]. Cardiac MRI is an excellent alternative modality for noninvasive assessment of patients with NCVM because it has several advantages, such as high spatial resolution, large field of view, and ability to detect thrombus and myocardial scar. In this case report, we describe MRI features of a patient with NCVM whose diagnosis was supported by echocardiography and clinical findings. 2. Case report A 33-year-old woman presented with shortness of breath and palpitations and had a history of heart failure for a number of years, particularly after the birth of her last child 7 years ago. She had a history of cardiac surgery at 5 years of age for what was described as a fibrous material over her pericardium. There was no record of a diagnosis of noncompaction at that time. Her mother died at 19 years of age from heart disease (specific type of the disease is unknown). Her uncle, maternal grandmother, and maternal grandfather had a similar heart disease, and her uncle refused a heart transplant. Upon admission, her stress test electrocardiogram demonstrated normal sinus rhythm. Blood studies showed normal results.
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X. Liu et al. / Clinical Imaging 32 (2008) 223–226
Contrast-enhanced cardiac MRI was performed on a 1.5-T clinical scanner (Avanto, Siemens, Erlangen, Germany) with a phase-array coil incorporating the Siemens total image matrix technology. Cardiac magnetic resonance cine was performed with a breathhold steady-state free precession (SSFP) sequence. Twenty-five phases were acquired per cardiac cycle, with
spatial resolution of 2.4×1.8×6.0 mm. Cines were obtained in vertical long-axis, four-chamber, left ventricular outflow tract and short-axis views. Cine images showed numerous abnormal trabeculations in the left anterior, apical, and inferior left ventricular wall, as well as the right ventricular wall, though to a lesser extent (Fig. 1A). In the short-axis view of the left ventricle, the ratio of noncompacted to
Fig. 1. Four-chamber (A) and short-axial (B) MRI cine image showed trabecular meshwork and deep intertrabecular recesses in left ventricular wall (arrow) and right ventricular wall (arrowhead). The ratio of the thickness of trabeculated myocardium and nontrabeculated myocardium of left ventricle was 3.8 at enddiastole. (C) Four-chamber MRI cine image showed an aneurysm (1.5×1.3 cm2) in the inferior right ventricular free wall at the apex at the end of systole (arrow). (D and E) Dynamic MRA demonstrated the structure of trabeculations more clearly, especially in the right ventricular wall (arrow). It also confirmed that the intertrabecular recesses were communicated with ventricular cavity. (F) Delayed-enhancement MRI showed a linear enhancement in the mid myocardium of basal septum suggesting scar (arrow). (G and H) TEE revealed significant trabeculations in the left ventricular apex and mid cavity (arrow), consistent with the findings of MRI.
X. Liu et al. / Clinical Imaging 32 (2008) 223–226
compacted myocardial layers (NC/C ratio) at the site of maximal wall thickness was 3.8 at end-diastole (Fig. 1B). A focal outpouching was detected in the inferior right ventricular free wall at the apex, suggesting a right ventricular aneurysm (Fig. 1C). There was impaired left ventricular systolic function (ejection fraction 37%) with severe akinesis and flattening of the septal wall. In addition, mild mitral regurgitation and moderate tricuspid regurgitation were demonstrated. Dynamic magnetic resonance angiography (MRA) was performed using single shot inversion recovery SSFP in a four-chamber view. The acquisition time per image was 250 msec. ECG-gating was utilized with the acquisition period occurring at end diastole. A total of 6 ml (0.2 mmol/kg) of Gadolinium-DTPA (Magnevist, Berlex Laboratories, NJ, USA) was injected at rate of 4 ml/s via a peripherally placed intravenous cannula. Noncompacted myocardium from both ventricles was more clearly visible on dynamic MRA images (Fig. 1D and E). In addition, a hypoperfusion was detected in the noncompacted myocardium in resting dynamic MRA images. Delayed-enhancement MRI was performed using inversion recovery turboFLASH sequence with magnitude and phase sensitive reconstruction 10 min after contrast administration in ventricular long-axis, four-chamber, threechamber, and short-axis views. A linear area of enhancement was present within the mid myocardium of the basal septum suggesting a scar (Fig. 1F). There was no evidence of intracardiac thrombus. Transesophageal echocardiography (TEE) revealed normal left ventricular size with significant trabeculations of the left ventricular apex and mid cavity (Fig. 1G and H). The NC/C ratio at end-systole was 3.5. Severe septal hypokinesis with global hypokinesis and severe systolic dysfunction were noted. The overall left ventricular ejection fraction was about 25%. In addition to a dilated and dysfunctional right ventricle, an akinetic apical segment of the right ventricular apex, possibly representing an apical aneurysm, was also detected. Trivial pericardial effusion was noted. Color Doppler flow revealed mild to moderate mitral regurgitation and moderate tricuspid regurgitation with moderate pulmonary hypertension.
3. Discussion In this case report, we describe the MRI findings in biventricular NCVM. Although NCVM more commonly affects the left ventricle, right ventricular involvement has also been described [5,7,9,10]. Additionally, we describe the utility of dynamic MRA and delayed enhanced imaging for better characterization of the left ventricular myocardium. Different definitions of NCVM by echocardiography have been proposed in previous studies [6–8]. Although these diagnostic echocardiographic criteria for NCVM are not uniform and not fully accepted in clinical practice, three
225
echocardiographic criteria were frequently used in the previous studies [5,7,11,12]: (1) numerous prominent trabeculations and deep intertrabecular recesses in the ventricular wall, (2), communication of the intertrabecular recesses with the ventricular cavity, and (3) an end-systolic NC/C ratio N2.0. The TEE findings in our case were consistent with these criteria. The end-systolic NC/C ratio was greater than 2.0, and most of the noncompacted segments are hypokinetic. In addition, color Doppler demonstrated flow in the intertrabecular recesses, suggesting the communication of intertrabecular recesses with ventricular cavity. Ritter et al. [9] and Burke et al. [10] reported that right ventricular noncompaction was involved in 41% (7/17) and 43% (6/14) of patients with NCVM, respectively. Because of the heavily trabeculated nature of the normal right ventricular apex, it is difficult to distinguish pathological trabeculations from the variants of normal patterns. To date, there are no diagnostic criteria that have been proposed in echocardiography of noncompaction of the right ventricle [5,7,9], or the diagnosis has been assessed on a purely qualitative basis [9]. However, based on pathohistologic study, Burke et al. [10] proposed a histological criteria for right ventricular noncompaction: transmural thickness of the noncompacted right ventricle greater than 75%. In our case, the diagnosis for right ventricle was established by qualitative assessment. Cardiac MRI with its superior spatial resolution and higher contrast between blood and myocardium is better suited to evaluating abnormalities of the ventricular myocardium than traditional echocardiography. Petersen et al. [3], based on a modified criteria (end-diastolic NC/C ratio N2.3), demonstrated that the sensitivity and specificity of MRI cine imaging for detecting NCVM were 86% and 99%, respectively. In addition, Korcyk et al. [13] proposed that trabecular mass of greater than 20% of total myocardial mass could be a more useful index for the diagnosis of NCVM. In our case, the end-diastolic NC/C ratio with MRI was 3.8, thus making a diagnosis based on echo criteria. Because noncompacted myocardium also exists in healthy, dilated, and hypertrophied hearts [3,5,11], when increasing diagnostic specificity for distinguishing pathological trabeculations, the measurement of NC/C ratio by MRI was determined at end-diastole; however, the echocardiographic values were taken at end-systole. MRI allows the best visual differentiation of the two layers at end-diastole due to its high spatial resolution. Cardiac MRI is not only useful for detecting the presence of abnormally trabeculated myocardium but may also demonstrate the extent and distribution of the abnormality. This is particularly beneficial when trabeculations are confined to the ventricular apex [3,5] or right ventricle, regions that are difficult to image by echocardiography. Previous studies performed by Jenni [7] and Oechslin [5] demonstrated that the typical distribution of prominent trabeculations in patients with NCVM were the left
226
X. Liu et al. / Clinical Imaging 32 (2008) 223–226
ventricular apical, lateral, and inferior segments. Meanwhile, these studies suggested that the assessment of prominent trabeculation distribution is useful for differentiating pathological trabeculations from the prominent trabeculations found in normal or hypertrophied hearts. Another study by Petersen et al. [3] also showed that noncompactions were predominantly localized in the left ventricular apical and mid-cavity (lateral and inferior) wall, but there were no differences between the distribution of noncompactions found in healthy, dilated, and hypertrophied hearts compared to patients with NCVM. Injection of contrast may help to further characterize the noncompacted myocardium. In this case report, MRA imaging more clearly demonstrated the trabeculations and also confirmed communication between the trabecular recesses and the ventricular cavity. Our study also showed resting hypoperfusion in the noncompacted muscle, a finding that has been described in previous studies [13,14]. Moreover, dynamic MRA may identify ventricular thrombus in the deep recesses between the trabeculations. There was no evidence of intracardiac thrombus in this study. Pathohistologic studies have demonstrated that ischemic lesions such as necrosis, fibrosis, and scar were associated with abnormalities of the myocardial microcirculation [7] and were widely distributed in the endocardial (nonecompacted) layer and subendocardial area [5,7,10]. Impaired microperfusion and subsequent scar tissue formation were believed to be associated with left ventricle dysfunction and lethal ventricular arrhythmias [5,7,15]. Jassal et al. [15] reported that delayed-enhanced cardiac MRI showed atypical scar within the abnormal trabeculations. In this case, we did not find the evidence of fibrosis within the trabeculations, but a linear scar was found in the basal septum. This may be related to the abnormal myocardial microcirculation in patients with NCVM. According to the pathohistologic study, myocardial fibrosis and scar may be present in the adjacent area of noncompaction or the area of compacted myocardium [7,10]. Ventricular aneurysm associated with NCVM was only previously reported in one case with a left ventricular aneurysm [4]. But in this case, the ventricular aneurysm was located in the right ventricle. Ventricular aneurysm associated with NCVM is thought to be caused by regional ventricular wall thinning and myocardial hypoperfusion due to abnormalities of the myocardial microcirculation in patients with NCVM [14]. The major clinical complications of NCVM are heart failure, atrial and ventricular arrhythmias, and thromboembolic events [5,6,16]. Heart failure is the most frequent event in hospital admission, and the prognosis of symptomatic patients is poor [5,16]. There is no specific treatment option for NCVM. Medical management varies with clinical manifestation, left ventricular ejection fraction, and presence or absence of arrhythmias. Oral anticoagulation is recom-
mended for NCVM with left ventricular systolic dysfunction, atrial arrhythmia, and local thrombi due to the increased risk of systemic embolism [5,17]. Heart transplantation should be considered for patients who have endstage heart failure. In conclusion, contrast-enhanced cardiac MRI demonstrates not only the morphological features of NCVM but also myocardial perfusion abnormalities and myocardial scar which represent severe complications of NCVM. References [1] Richard P, McKenna W, Bristow M, et al. Report of the 1995 World Health Organization/International Society and Federation of Cardiology Task Force on the definition and classification of cardiomyopathies. Circulation 1996;93:273–83. [2] Sedmera D, Pexieder T, Vuillemin M, et al. Developmental patterning of the myocardium. Anat Rec 2000;258:319–37. [3] Petersen SE, Selvanayagam JB, Wiesmann F, et al. Left ventricular noncompaction: insights from cardiovascular magnetic resonance imaging. J Am Coll Cardiol 2005;46:101–5. [4] Sasse-Klaassen S, Probst S, Gerull B, et al. Novel gene locus for autosomal dominant left ventricular noncompaction maps to chromosome 11p15. Circulation 2004;109:2720–3. [5] Oechslin EN, Attenhofer C, Jost H, Rojis JR, et al. Long-term followup of 34 adults with isolated left ventricular noncompaction: a distinct cardiomyopathy with poor prognosis. J Am Coll Cardiol 2000;36:493–500. [6] Chin TK, Perloff JK, Williams RG, et al. Isolated noncompaction of left ventricular myocardium. A study of eight cases. Circulation 1990;82:507–13. [7] Jenni R, Oechlin E, Schneider J, et al. Echocardiographic and pathoanatomical characteristics of isolated left ventricular noncompaction: a step towards classification as a distinct cardiomyopathy. Heart 2001;86:666–71. [8] Stöllberger C, Finsterer J. Left ventricular hypertrabeculation/noncompaction. J Am Soc Echocardiogr 2004;17:91–100. [9] Ritter M, Oechslin E, Sutsch G, Attenhofer C, Schneider J, Jenni R. Isolated noncompaction of the myocardium in adults. Mayo Clin Proc 1997;72:26–31. [10] Burke A, Mont E, Kutys R, et al. Left ventricular noncompaction: a pathological study of 14 cases. Hum Pathol 2005;36:403–11. [11] Biagini E, Ragni L, Ferlito M, et al. Different types of cardiomyopathy associated with isolated ventricular noncompaction. Am J Cardiol 2006;98:821–4. [12] Frischknecht BS, Jost CHA, Oechslin EN, et al. Validation of noncompaction criteria in dilated cardiomyopathy, and valvular and hypertensive heart disease. J Am Soc Echocardiogr 2005;18:865–72. [13] Korcyk D, Edwards CC, Armstrong G, et al. Contrast-enhanced cardiac magnetic resonance in a patient with familial isolated ventricular noncompaction. J Cardiovasc Magn Reson 2004;6:569–76. [14] Sato Y, Matsumoto N, Yoda S, et al. Left ventricular aneurysm associated with isolated noncompaction of the ventricular myocardium. Heart Vessels 2006;21:192–4. [15] Jassal DS, Nomura CH, Ncilan TG, et al. Delayed enhancement cardiac MR imaging in noncompaction of left ventricular myocardium. J Cardiovasc Magn Reson 2006;8:489–91. [16] Murphy RT, Thaman R, Blanes JG, et al. Natural history and familial characteristics of isolated left ventricular non-compaction. Eur Heart J 2005;26:187–92. [17] Stöllberger C, Finsterer J. Left ventricular hypertrabeculation/noncompaction and stroke or embolism. Cardiology 2005;103:68–72.