A Case of Left Ventricular Noncompaction

A previously healthy 26-yr-old man presented to a community hospital complaining of abdominal pain, nausea, shortness of breath, and lower extremity edema over 5 days. His work-up indicated decompensated heart failure. A transthoracic echocardiogram (TTE) revealed severe left ventricular (LV) enlargement and dysfunction with an ejection fraction of 10%. He was referred to the heart failure clinic of University of Colorado at Denver Health Sciences Center for possible ventricular assist device placement or transplant because of his inotrope-dependent heart failure. TTE evaluation demonstrated a bicuspid aortic valve and prominent trabeculation, resembling deep sinusoids in the myocardium, in the posterolateral aspect of the LV consistent with LV noncompaction. A contrast TTE study, in which opacification of the LV cavity permits enhanced visualization of the ventricular walls, supported the diagnosis (Fig. 1, Video clip 1; please see video clip available at www.anesthesia-analgesia.org). The patient was diagnosed with acute onset of New York Heart Association Class IV heart failure secondary to LV noncompaction and was listed for transplant.Figure 1.: Transthoracic contrast enhanced image of the left ventricle. A transthoracic apical four-chamber view of the heart is demonstrated. The contrast material is visualized as opacification of the ventricular cavity (A), enhancing the identification of the myocardium which is black (B) and invading the noncompacted myocardium making the hypertrabeculation (C) visible.The patient underwent cardiac transplantation 6 wk later. His intraoperative transesophageal echocardiogram confirmed the TTE findings. Segmental thickening found in the LV wall consisted of a thickened endocardial layer with deep trabeculations, and a thin epicardial layer in the apical area as well as in part of the mid-lateral wall (Fig. 2, Video clip 2; please see video clip available at www.anesthesia-analgesia.org). The surgery was performed without complications and the patient was discharged from the hospital on postoperative day 18.Figure 2.: Transgastric short axis view of the apical area of the left ventricle. A compacted epicardial layer, measuring 0.46 cm (A), and a noncompacted endocardial layer, measuring 1.16 cm (B), with trabeculation, are demonstrated. The noncompaction to compaction ratio was >2 representing 1 of the diagnostic criteria of noncompaction. Noncompaction was determined in the apical inferior, septal, anterior and lateral wall.DISCUSSION LV noncompaction is characterized by numerous prominent trabeculations and deep intertrabecular recesses in communication with the ventricular cavity.1 It is a rare primary cardiomyopathy that is an isolated finding in 74% of cases, or is associated with congenital heart disease in 26% of cases.1,2 The overall prevalence is unknown, but a review of patients having echocardiography over 15 yr reported a prevalence of 0.014%.3 LV noncompaction is thought to be caused by disruption of compaction of the loose myocardial meshwork during fetal development, possibly triggered by mutations of sarcomere protein genes.4 The clinical symptoms of LV noncompaction include heart failure, thromboembolic events, and arrhythmias, including ventricular tachycardia and atrial fibrillation.1–3 Echocardiography, especially transesophageal echocardiogram, is the primary diagnostic tool of choice. Three main echocardiographic criteria have been established3: The segmental thickening found in the LV wall consists of two layers: a thickened endocardial layer with deep trabeculations and a thin epicardial layer. The end-systolic ratio of noncompacted to compacted layers of >2 is diagnostic for noncompaction. The pathology is predominantly localized to mid-lateral, apical, and mid-inferior areas. Concomitant regional hypokinesis need not be confined to noncompacted segments. Color Doppler or contrast evaluation demonstrates flow within the trabecular recesses. LV noncompaction has a high morbidity and mortality rate. In a study of 34 patients, 53% developed heart failure, 41% suffered ventricular tachyarrhythmias, 12% required transplant and 35% died at 44-mo follow-up.3 Noncompacted myocardium involved the LV in 62% and both ventricles in 38% of the patients in 1 case series.2 A ratio of noncompacted to compacted myocardium more than 3 and involvement of 3 or more segments (American Heart Association 17-segment model) are indicators of poor prognosis.2 Our patient had a combination of bicuspid aortic valve and noncompaction. A report with two cases of combined bicuspid aortic valve and ventricular noncompaction demonstrated poor prognosis and right ventricular involvement.5 There has been inconsistency in the terminology as LV noncompaction is frequently mentioned to be synonymous with LV hypertrabeculation. Hypertrabeculation is defined by more than three trabeculations in the LV, but it may not show the two-layered wall structure classically described for noncompaction.6 Importantly, LV hypertrabeculation is a secondary cardiomyopathy that has been associated with neuromuscular disorders (NMD), such as metabolic myopathy, Leber’s hereditary optic neuropathy, myotonic dystrophy, Becker muscular dystrophy, Duchenne muscular dystrophy, and NMD of unknown etiology.6 The exact incidence is unknown, but in 1 study 80% of patients with LV hypertrabeculation were diagnosed with a NMD.6 Further genetic studies are needed to elucidate whether LV noncompaction and LV hypertrabeculation are different entities or represent similar genetic background. For now, specific concerns regarding anesthetic management would be to address the history of NMD in both clinical entities as muscle relaxation induced by succinylcholine could precipitate severe hyperkalemia. In conclusion, LV noncompaction is a rare primary genetic cardiomyopathy principally diagnosed by echocardiography. The anesthesiologist should inquire about symptoms from arrhythmias, embolic events or heart failure, as well as NMD history in preparation for the anesthetic care.