Danon disease is a rare X-linked dominant genetic disorder that manifests with a clinical triad of cardiomyopathy, skeletal myopathy, and intellectual disability. It is caused by mutations in the lysosome-associated membrane 2 (LAMP2) gene. We report one case of Danon disease and his family members, characterized by ventricular pre-excitation, ventricular hypertrophy, abnormal muscle enzymes, and aberrant liver function. All the patients were confirmed to have Danon disease through genetic screening. Relevant literature was reviewed as a reference for the diagnosis and treatment of the disease.

A 79-year-old Caucasian male was referred to cardiology clinic because the electrocardiogram showed premature atrial complexes and pre-excitation (delta waves) thought to be consistent with Wolff-Parkinson-White (WPW) syndrome. He did not report symptoms of palpitations or syncope. Careful analysis of the electrocardiogram revealed a fascicular-ventricular pathway (FVP) responsible for pre-excitation. Differentiating FVP from WPW syndrome is essential as the risk profile is different with each. Electrocardiographic observations that could help identify the presence of an FVP and its diagnostic, prognostic, and therapeutic implications are presented.

BACKGROUND: Antegradely conducting left lateral accessory pathways are a risk for supraventricular tachycardias and pre-excited atrial fibrillation. Rarely, an anomalous coronary sinus can cause difficulty in locating the pathway. The left circumflex coronary artery and obtuse marginal branches supply the posterolateral left ventricle. We describe a case report of a high-risk accessory pathway associated with an anomalous coronary sinus which, between successive electrophysiology studies, was obliterated by a felicitous acute coronary syndrome in the left circumflex territory.
METHODS: A 49-year-old male with palpitations and manifest pre-excitation was referred for electrophysiology study. Initial study revealed a high-risk left lateral accessory pathway with antegrade effective refractory period of 240 ms and rapidly conducting pre-excited atrial fibrillation. The coronary sinus could not be cannulated to localize the pathway. Coronary angiography and cardiac computed tomography showed an anomalous coronary sinus emptying into the right atrial free wall and patent coronaries. While awaiting repeat electrophysiology study, the patient suffered an acute coronary syndrome with immediate loss of previously visible pre-excitation on electrocardiogram, and underwent stenting of an occluded marginal branch of the circumflex. Repeat electrophysiology study demonstrated a now low-risk accessory pathway (effective refractory period 390 ms). Since infarction, the patient\'s palpitations have fully settled with all subsequent electrocardiograms devoid of manifest pre-excitation.
CONCLUSIONS: Left lateral accessory pathways, which can associate with an anomalous coronary sinus, derive from tissue similar to normal ventricular myocardium and are vulnerable to ischaemic insults in the area subtended by the circumflex artery.

A 75-year-old woman, who had never exhibited a delta wave before, was diagnosed with sigmoid colon cancer and underwent surgical operation. Takotsubo cardiomyopathy (TC) occurred shortly after the operation. About 2 weeks following the onset of TC, a 12‑lead electrocardiogram revealed a delta wave that was present for 50 days, and the patient was diagnosed with transient ventricular pre-excitation. The delta wave disappeared prior to patient\'s discharge and was never observed thereafter. This transient appearance of a delta wave may be related to a pathological modulation of the autonomic nervous system during the acute phase of TC.

BACKGROUND: PRKAG2 syndrome (PS) is a rare, early-onset autosomal dominant inherited disease caused by mutations in PRKAG2, the gene encoding the regulatory γ2 subunit of adenosine monophosphate-activated protein kinase. PRKAG2 syndrome is associated with many cardiac manifestations, including pre-excitation, arrhythmias, left ventricular hypertrophy, and chronotropic incompetence frequently leading to early pacemaker placement. A meta-analysis of genome-wide association data in subjects with chronic kidney disease (CKD) identified a susceptibility locus in an intron of PRKAG2, which has been replicated in other studies. However, CKD has not been reported in patients with PS or mutations in PRKAG2.
METHODS: We report a case of a woman diagnosed at age 27 with PS when she presented with atrial fibrillation and pre-excitation on electrocardiogram. By age 35, she had developed mild renal insufficiency and a biopsy demonstrated IgA nephropathy (IGAN).
CONCLUSIONS: This is the first reported case of IGAN in a patient with PS. We discuss both PS and IGAN and the potential mechanisms by which they could be related.

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Pre-excited, fast conducting atrial fibrillation (AF) is a serious life-threatening arrhythmia that requires urgent pharmacological or electrical cardioversion. When anti-arrhythmic medications fail to restore sinus rhythm, biphasic, direct current (DC) cardioversion is required. Appropriate synchronization of the DC shock with the QRS is crucial, however not easily achieved. Since the QRS-T complexes in pre-excited AF are severely distorted, the diagnosis of inaccurate synchronization may be overlooked. Here, we report a unique case where during electrical cardioversion of pre-excited AF with inappropriate synchronization on the T wave inadvertently resulted in ventricular fibrillation (VF), and review the literature.

Electric injury can cause a variety of cardiac arrhythmias. Atrial fibrillation as a result of such injury is very rare. We present a case of a young asymptomatic patient who developed acute atrial fibrillation with antegrade conduction over the atrioventricular bypass tract and very high ventricular rate after accidental low voltage electric injury, which was reverted successfully by DC shock.