Isolated Non-Compaction of the Ventricular Myocardium Associated With Long QT Syndrome A Report of 2 Cases

Abstract

solated non-compaction of the ventricular myocardium (INCVM) is a relatively newly defined disorder of the endomyocardium characterized by prominent ventricular trabeculations and deep intertrabecular recesses. 1 Clinical manifestations include a depressed left ventricular (LV) function, ventricular arrhythmia, and systemic embolization. 2,3 INCVM has been reported to be associated with several electrocardiographic changes such as ST depression and flat or negative T waves, bundle branch block, and Wolff-Parkinson-White (WPW) syndrome. [2][3][4] To the best of our knowledge, a long QT interval has not been reported on previously.We report 2 cases of INCVM with long QT syndrome (LQTS). Case Report Patient 1The patient was a boy aged 1 day old, who had no family history of sudden death or arrhythmia, and electrocardiograms (ECGs) of his parents showed no abnormality. He was born normally in a maternity hospital at the gestational age of 38 weeks. The Apgar score was 8 points at 1 min after birth. He was given low-dose oxygen because of slight cyanosis. At 13 h after birth, he showed tachypnea and systemic cyanosis.When he was admitted to our hospital, his condition was severe. His respiratory rate was 60 breaths/min and heart rate was 130 beats/min. His systolic blood pressure was 60 mmHg. His head and face was edematous. No heart murmur was audible. Hepatosplenomegaly was not recognized.Blood gas analysis indicated severe metabolic acidosis; the base excess was -9.2 mmol/L and pH was 7.305. Both AST and CK were elevated. In particular, CK was as high as 2,830 IU/L. Mild hypocalcemia (7.8 mg/dl) was present and other serum electrolytes including magnesium (2.3 mg/dl) were within normal limits. A physical examination and laboratory data showed marked stress during gestation or circulatory shock of an unknown cause. A chest X-ray revealed cardiomegaly, and the cardiothoracic ratio (CTR) was 68%. The ECG on admission showed left bundle branch block (LBBB) and a long QT time (Figure 1). An echocardiography showed that the ventricular myocardium was thickened and that the endocardial trabeculation was prominent at the apex, especially in the right ventricle. There were no congenital heart defects, and the ejection fraction of the left ventricle (LVEF) was 10%.A few minutes after supplemental calcium infusion, polymorphic ventricular tachycardia (VT) with torsades de pointes and sustained VT were detected on an ECG moniter (Figure 1). Lidocaine 1 mg/kg was infused initially, but it was ineffective. Even though cardioversion was performed several times, it had only a transient effect on resolving polymorphic and sustained VT. After 1 mmol/kg MgSO4 was administered, sustained VT was resolved, and MgSO4 was infused at a rate of 0.1 mmol · kg -1 · h -1 to prevent sustained VT with torsades de pointes.After VT was resolved, the LVEF was gradually improved to 60% and the CTR based on a chest X-ray was normalized at the age of 4 days. An ECG showed a narrow QRS pattern, not a bundle branch block, and QTc was still prolonged to...

Long-Term Follow-up of Patients With Isolated Left Ventricular Noncompaction - Role of Electrocardiography in Predicting Poor Outcome -

“…Indeed, both benign as well as life-threatening arrhythmias, including VT and ventricular fibrillation, may readily be encountered in these patients. 4,9,25, 26 In the current study, none of the ECG parameters was predictive of severe ventricular arrhythmias during follow-up. Identifying patients likely to suffer malignant ventricular arrhythmias hence remains a challenge in patients with IVNC.…”

Left ventricular non-compaction and its cardiac and neurologic implications

“…From that time, they mature by cardiomyocyte recruitment and proliferation [3,46]. Between gestational weeks 5 and 8, the developing myocardium gradually condenses and the intertrabecular spaces flatten and disappear coinciding with the developing coronary vasculature [3,46,55]. This process typically progresses from the epicardium to the endocardium, from the base to the apex, and is more pronounced in the left than the right ventricle [56].…”

“…Single LVHT patients may present with hereditary sick-sinus syndrome or long-QT syndrome due to mutations in the cardiac sodium-or potassium channels ( Table 1). The 24-h Holter monitoring may reveal sinusbradycardia, ventricular bigeminia, nonsustained ventricular tachycardia [76], T-wave alternans, or torsades de pointes [55], but some authors regard Holter monitoring as insufficient to detect ventricular tachycardias and propose loop recording [76]. Whether ECG abnormalities other than severe ventricular arrhythmias have prognostic implications is unknown, but in a study on 78 LVHT patients, a striking overlap between ventricular conduction delay, atrial conduction delay, QT-prolongation, atrial dilatation, and systolic dysfunction was found [72].…”

Spectrum of Cardiac Arrhythmias in Isolated Ventricular Non-Compaction

“…8 LVNC has also been observed in conjunction with inherited long QT syndrome secondary to KCNH2 mutations; Ogawa et al described one pediatric patient with an A561V mutation in the pore region, and another with a D501N mutation in the nonpore region. 9 Furthermore, it has been associated with the ryanodine receptor gene (RYR2) exon 3 deletion that is described to be a causative mutation in catecholaminergic ventricular tachycardia (CPVT) and in dilated cardiomyopathy. In a series published by Ohno et al, two unrelated individual CPVT probands, each with large RYR2 exon 3 deletions, and concomitant LVNC, were identified.…”

“…The authors raise the concern regarding the higher risk of SCD in such patients, and recommend the implantation of an ICD. 31 Campbell et al described an interesting case of CPVT occurring in a patient who developed LVNC, and who was found to have deletion of exon 3 of the RYR2 gene encoding the ryanodine receptor. This patient suffered multiple expertional syncopal episodes as a child and adolescent, with one episode occurring with documented AF.…”