Traumatic sinus node dysfunction

Sick sinus syndrome and atrial fibrillation in older persons - A view from the sinoatrial nodal myocyte

Sick sinus syndrome remains a highly relevant clinical entity, being responsible for the implantation of the majority of electronic pacemakers worldwide. It is an infinitely more complex disease than it was believed when first described in the mid part of the 20th century. It not only involves the innate leading pacemaker region of the heart, the sinoatrial node, but also the atrial myocardium, predisposing to atrial tachydysrhythmias. It remains controversial as to whether the dysfunction of the sinoatrial node directly causes the dysfunction of the atrial myocardium, or vice versa, or indeed whether these two aspects of the condition arise through some related underlying pathological mechanism, such as extracellular matrix remodeling, i.e., fibrosis. This review aims to shed new light on the myriad possible contributing factors in the development of sick sinus syndrome, with a particular focus on the sinoatrial nodal myocyte. This article is part of a Special Issue entitled CV Aging.

Effects of cardiac contusion in isolated perfused rat hearts

Myocardial contusion is frequently suspected after blunt chest trauma, but the exact mechanisms of resulting cardiac dysfunction and the time course for enzymatic alterations have not yet been fully understood. Therefore, we investigated pathophysiological aspects of myocardial contusion in a controlled animal model. Male Wistar rat hearts were studied in an isolated perfusion model and were divided into two groups: control (n = 4) and heart contusion (n = 6) groups. The cardiac contusion was produced by a single blow with a weighted pendulum (m = 44 g, height = 20 cm). Functional implications of the contusion were examined in an "isolated perfused heart" model. Troponin 1 concentrations were determined in the perfusate. Cardiac contusion resulted in an increase of coronary perfusion pressure (CPP) of 9 mmHg (P < 0.05, 20 min postcontusion versus baseline and control), followed by a significant increase of left ventricular end-diastolic pressure (LVEDP) of 6 mmHg (P < 0.05, 20 min postcontusion versus baseline and control). Heart contusion was followed by an early increase of troponin 1 (+0.82 ng/mL). The troponin 1 concentration decreased again and, after 20 min, baseline levels were reached. The control group showed no such changes. In this model, high troponin 1 levels after cardiac contusion suggest direct damage to the myocardium. First functional response was shown by the alteration of the coronary perfusion, followed by impaired diastolic function, which persisted even after lowering of the troponin 1 levels.

MILITANCY TRAUMA : PENETRATING AND NONPENETRATING CARDIAC INJURY

Two hundred and eighty patients with serious chest injuries were treated at a service hospital during a period of 41 months. Out of 9 patients who suffered cardiac trauma S had penetrating cardiac injuries, 2 had penetrating pericardial injury and 2 patients had myocardial contusions. Myocardial contusions simulated myocardial infarction. All patients except one had polytrauma, associated injury to the lung or intra-abdominal organs. Early evacuation, resuscitation, high index of suspicion for cardiac injury and prompt surgical intervention were the keys to successful management in these patients. Thoracotomy was performed to repair the myocardial perforation and lacerated lung injuries. Associated infra-abdominal injuries were managed with laparotomy. Two patients died due to lack of cardiopulmonary bypass facilities and resistant cardiac arrhythmias. Seven patients had uneventful recovery.

Sinoatrial Wenckebach associated with blunt cardiac injury

A 20-year-old man developed sinoatrial Wenckebach after moderate blunt chest and cardiac trauma from a motor vehicle accident. This unusual dysrhythmia is manifested by grouped beating, a constant PR interval, progressive shortening of the cycle length, and repetitive pauses. Sinoatrial Wenckebach has not previously been described in association with blunt cardiac injury.