Michitaka Uesugi

Acute myocardial infarction caused by spontaneous postpartum coronary artery dissection.

Background A 34-year-old postpartum woman presented at hospital with chest pain. She had experienced an uneventful delivery of a healthy infant and had no known coronary risk factors. Electrocardiography demonstrated an acute myocardial infarction, which resolved on intravenous glyceryl trinitrate infusion. Coronary angiography revealed diffuse narrowing of the left anterior descending artery and tapering of the left main trunk, but there were no obvious hallmarks of intimal dissection.Investigations Electrocardiography, coronary angiography, multidetector CT and intravascular ultrasonography.Diagnosis Postpartum coronary artery dissection.Management The lesion was stabilized with orally administered amlodipine, aspirin, ticlopidine and pitavastatin, along with intravenous heparin and glyceryl trinitrate. The patient was later discharged on bisoprolol, aspirin, pitavastatin and temocapril.

Role of Na+‐H+ Exchange on Reperfusion Related Myocardial Injury and Arrhythmias in an Open‐Chest Swine Model

The inhibition of Na+‐H+ exchange (NHE) with amiloride analogues in vitro has been shown to prevent reperfusion arrhythmias and additional cell necrosis. Inhibition of intracellular Ca2+ overload via NHE inhibition has been suggested as a mechanism of these protective effects. The aim of this study was to examine whether treatment with amiloride analogues reduces the incidence of reperfusion arrhythmias and limits infarct size in vivo. Open‐chest swine were exposed to a 30‐minute left anterior descending artery (LAD) occlusion and 180 minutes of reperfusion during atrial pacing at 150 ppm. Intravenous 5‐(N,N‐dimethyI)‐amiloride (AML, 5 μg/kg per min) was administered in the treatment group (n = 7) and intravenous saline in the control group (n = 7), starting 10 minutes before coronary occlusion. The infusion was continued during ischemia and reperfusion. The area at risk was defined by monastral blue dye and infarct size by triphenyltetrazolium chloride staining. Limb leads ECG and monophasic action potentials (MAPs) from the epicardium in the ischemic area were recorded. There was no significant difference in the size of the area at risk and hemodynamic parameters between the groups. However, the infarcted area was 0.4%± 1.0% of the area at risk in the treatment group, whereas it was 62%± 29% in the control group (P < 0.05). Pathological examination (Hematoxylin‐eosin and mallory s phosphotungstic acid‐hematoxylin staining) revealed that all of the infarcted area consisted of contraction band necrosis. MAP duration in both groups was significantly shortened during ischemia. After reperfusion, MAP duration in the treatment group recovered earlier than that of control group. However, there was no significant difference in the incidence of ventricular tachyarrhythmia between the groups. Inhibition of NHE with AML prevented reperfusion related cell necrosis in the in vivo swine model, but did not reduce the incidence of ventricular tachyarrhythmia.

Asymptomatic Brugada syndrome associated with postural orthostatic tachycardia syndrome: Does autonomic disorder increase propensity for future arrhythmic events?

Autonomic imbalance may work as a modifying factor for initiating lethal arrhythmia in patients with Brugada syndrome. A 26‐year‐old man with episodes of near syncope was given a diagnosis of an autonomic disorder, postural orthostatic tachycardia syndrome (POTS). The patient spontaneously showed typical Brugada‐type ECG, and ventricular fibrillation was induced by programmed electrical stimulation, which allowed the further diagnosis of Brugada syndrome. Although it seems that Brugada syndrome is asymptomatic, its uncommon association of POTS may increase the risk for future arrhythmic events in this patient. (PACE 2004; 27:537–540)

Presence of myocardial hypoenhancement on multidetector computed tomography after primary percutaneous coronary intervention in acute myocardial infarction predicts poor prognosis

BACKGROUND Recent research has suggested that patients with greater delayed contrast-enhanced size by multidetector computed tomography (MDCT) are more likely to experience adverse cardiac events and have poor prognoses over the long term. The myocardial hypoenhancement area in the delayed contrast-enhanced effect suggests microvascular obstruction. The outcomes of patients with a hypoenhancement area detected by MDCT have not been clear. We examined the clinical importance of myocardial hypoenhancement detected by delayed contrast-enhanced MDCT after percutaneous coronary intervention (PCI) in patients with acute myocardial infarction. METHODS AND RESULTS In 80 patients with acute myocardial infarction, MDCT was performed immediately after primary PCI. We investigated the outcomes of the patients with hypoenhancement detected by MDCT. Myocardial hypoenhancement was observed in 14 patients (17.5%). All 14 of these patients with hypoenhancement had a transmural infarction, and their infarct volume was significantly higher than those of the patients without hypoenhancement (n=66). During the median follow-up period of 309 days, the appearance of myocardial hypoenhancement was associated with the presence of slow flow/no-reflow, time from onset to reperfusion ≥6 h, aging, smoking, chronic kidney disease, and hyper-low-density lipoprotein cholesterolemia. The incidence of major adverse cardiovascular events (MACE) was significantly higher in the patients with hypoenhancement compared to those without hypoenhancement, regardless of the myocardial infarct volume. CONCLUSIONS These results indicate that the presence of myocardial hypoenhancement in delayed contrast-enhanced MDCT after PCI as well as the extent of infarct area is an important predictor of MACE.

Adenosine-Sensitive Focal Reentrant Atrial Tachycardia Originating From the Mitral Annulus-Aorta Junction

Adenosine‐sensitive reentrant atrial tachycardia (AT) has been recognized to originate from the confined area of either the right or left atiroventricular nodal regions. We describe a case with adenosine‐sensitive focal AT which was successfully ablated at the uncommon focus located at the mitral annulus‐aorta junction. The mode of AT initiation during the atrial extrastimulus suggested as the mechanism tachycardia reentry; AT was terminated by a bolus of 2 mg of adenosine 5’‐triphosphate. These electrophysiological features are possibly associated with a substrate involved in the mitral annulus‐aorta junction with node‐like properties that is responsive to adenosine.

A case of fulminant myocarditis associated with novel N1H1 influenza successfully treated by percutaneous cardiopulmonary support system

We report a case of fulminant myocarditis associated with N1H1 influenza virus infection. N1H1 was confirmed by a polymerase chain reaction assay and she was treated with oseltamivir phosphate. She was admitted to the hospital because of respiratory distress, however, echocardiography revealed severely depressed wall motion followed by refractory ventricular fibrillation. Extracorporeal circulation by emergent percutaneous cardiopulmonary support system was required to maintain hemodynamic stability. Cardiac function was spontaneously and gradually restored within a week. Findings from biopsy samples taken on day 1 and day 23 were consistent with acute myocarditis.

Benefits of Implantable Cardioverter Defibrillators in Older Patients

Background: The benefits of implantable cardioverter defibrillators (ICDs) have not been fully elucidated in older individuals in whom a comorbidity is relatively high and life expectancy is generally short. We aimed to evaluate the benefits of ICDs in older patients. Methods: Consecutive 171 ICD recipients (male 77.2%, mean age of 63.6±12.4 years old, left ventricular ejection fraction of 44.0±18.8%, ischemic cardiomyopathy 35.1%, primary prevention ICD 47.4%) were prospectively followed-up for 45.4±34.7 months. The patients ≥70 years of age (n=67) were compared with the remaining patients (n=104) in terms of appropriate/inappropriate ICD therapies and the mortality by using Kaplan-Meier analysis. Results: Mortality was 34.4% in the patients ≥70 years of age and 13.5% in the others; overall survival was significantly lower in the older patients than in the younger patients (log-rank p=0.0005). However, the proportion of the patients who had appropriate/inappropriate therapies were similar between older and younger patients (30.0% versus 33.7%, 17.9% versus 17.3%, respectively); event-free survival from appropriate or inappropriate therapies did not significantly differ between the two groups (log-rank p=0.39, 0.20, respectively). Conclusions: ICD therapy may be equally beneficial to reduce arrhythmic death in older patients as in younger patients.

Novel Technique to Facilitate Defibrillator Lead Implantation via Cephalic Vein Cutdown by Means of a Reference Catheter and a Specially Designed Long Sheath

The cephalic vein is recommended as the access route for an implantable cardioverter defibrillator lead to avoid complications associated with subclavian vein puncture; however, cephalic vein cutdown is not necessarily preferred, mainly because of procedural complexity. To facilitate cephalic vein cutdown, we have devised the following method. An 8 Fr catheter is placed in the cephalic vein over a guidewire inserted percutaneously from the left peripheral cephalic vein. The catheter, which is palpable beneath the skin prior to incision, indicates the location of the cephalic vein, facilitating its isolation. A specially designed 9 Fr tear‐away sheath‐dilator unit is used to place leads. With its long‐tapered and curved tip, the unit is easy to insert, even when the cephalic vein is stenotic or tortuous. The 30‐cm‐long sheath reaches the right atrium, and thus the lead is advanced directly to the right atrium without risk of vascular injury. This technique may be feasible in the majority of patients and can even be used by inexperienced implanters.

Restoring the Recurrent Extrusion of the Subcutaneously Implanted Defibrillator by Means of Subpectoral Replacement: The Benefits of Subpectoral Implantation in the Current ICD Era

A 72‐year‐old man with a thin build had an ICD system with a generator implanted at left prepectoral space. The generator was exposed through thin overlying skin at 11 months following surgery. Although it was undermined with the adjacent skin, it was exposed again 6 months later. The generator was replaced in the ipsilateral subpectoral space. Since then, no signs of recurrence have been observed for the subsequent 12 months, with the patient pleased with its cosmetic appearance. This case illustrates the benefits of subpectoral implantation in the current ICD era in which subcutaneous implantation is common.