Mechanodefibrillator dissociation due to prolonged sinus arrest / Mecano disociación del desfibrilador debido a un paro sinusal prolongado

To the editor, Sinus arrest and cardiac arrest are two different terms which are often confused by many. This confusion often leads to inappropriate cardiopulmonary resuscitation (CPR) when patient is connected to defibrillator. Sinus arrest is defined as transient pause in Sino-atrial firing for more than 3 s1. When sinus arrest occurs, other latent pacemakers (atrial myocardium, cells nearby atrioventricular node, and His purkinje system) usually starts firing until Sino-atrial node recover. Sinus arrest can be prolonged till other pacemakers starts firing2. Cardiac arrest occurs when these latent pacemakers does not take up the job of alternate firing. Prolonged sinus arrest in a defibrillator may look like a cardiac arrest which might lead to unnecessary CPR. Here, we would like the put forward a new term “mechano - defibrillator dissociation” which occurs because of prolonged sinus arrest. We should be aware this, so that inappropriate CPR could be avoided. We, emergency physician also faced similar situation while resuscitating a patient because of mechano - defibrillator dissociation caused by prolonged sinus arrest/pseudo cardiac arrest. A 52-year-old male diabetic, hypertensive, and chronic alcoholic came to our emergency department (ED) with history of giddiness, syncope, and palpitation. On arrival to ED, patient was drowsy, diaphoretic, and hypotensive. Patient was connected to defibrillator which showed a heart rate of 35/min and saturation was 90% in room air. ECG showed complete heat block (CHB) and point of care echocardiography showed reduced ejection fraction.

Permanent Pacemaker Implantation in a Patient with MELAS Syndrome / 대한내과학회지

A 35-year-old male patient with heart and renal failure and pneumonia was transferred to our department due to recurrent cardiac standstill with syncope. He had been diagnosed as and treated for MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes) syndrome for the past 3 years. Electrocardiography (ECG) showed the Wolff-Parkinson-White pattern, and an echocardiogram showed hypertrophic cardiomyopathy. He developed syncopal attacks intermittently, and ECG monitoring showed intermittent bradycardia. His Holter monitoring showed several episodes of 5-16 seconds of sinus arrest. We conducted an electrophysiological study to evaluate the arrhythmia. During atrial and ventricular extra-stimuli, cardiac standstill developed several times, and the duration of pauses varied from 2.5 to 5.5 seconds. Abrupt asystolic events also developed accompanying syncopal attacks that were not related to the extra-stimuli. We decided to implant a permanent pacemaker. The patient's syncopal episodes disappeared after implantation of a DDD type pacemaker.

Permanent Pacemaker for Syncope after Heart Transplantation with Bicaval Technique

Sinus node dysfunction occurs occasionally after heart transplantation and may be caused by surgical trauma, ischemia to the sinus node, rejection, drug therapy, and increasing donor age. However, the timing and indication of permanent pacemaker insertion due to sinus node dysfunction following heart transplantation is contentious. Here, we report a case of a permanent pacemaker insertion for syncope due to sinus arrest after heart transplantation, even with a bicaval technique, which has been known to associate with few incidences of sinus node dysfunction.

The Relationship between the Left Atrial Volume and the Maximum P-wave and P-wave Dispersion in Patients with Congestive Heart Failure

PURPOSE: A maximum P-wave duration (Pmax) of > or = 110msec and a P-wave dispersion (PWD) > or = 40msec are accepted indicators of a disturbance in interatrial conduction and an inhomogeneous propagation of the sinus impulse, respectively. The left atrial (LA) volume has been reported to be strongly associated with a systolic and diastolic dysfunction and is considered to be an index of atrial remodeling. We aimed to investigate the relationship between LA volume and Pmax or PWD in patients with congestive heart failure (CHF). PATIENTS AND METHODS: Sixty-one patients with CHF were enrolled in this study. The study population was classified into four groups: two groups were divided according to the Pmax (> or = 110msec or or = 40msec or or = 110ms or a PWD > or = 40ms and those with a Pmax < 110ms or a PWD < 40ms. The LAVi was independently associated with a disturbance in interatrial conduction and an inhomogeneous propagation of the sinus impulse. The LAVi can be used to identify patients with a disturbance in interatrial conduction and an inhomogeneous propagation of the sinus impulse with reasonably good accuracy. CONCLUSION: We concluded that a disturbance in interatrial conduction and an inhomogenous propagation of the sinus impulse in patients with CHF is associated with an increase in the LA volume and a deleterious systolic and diastolic dysfunction.