John N. Catanzaro

Exertional rhabdomyolysis and renal failure in patients with sickle cell trait: is it time to change our approach?

Abstract Based upon numerous reported cases and despite widespread beliefs to the contrary, sickle cell trait (SCT) may be deemed a quantifiable risk factor in certain subsets of patients. As a result of common misconceptions regarding SCT, most individuals with the condition are generally not informed regarding the possible consequences of certain activities such as venturing to high altitudes or participating in overly exertional physical activities. Acute exertional rhabdomyolysis is a potentially serious clinical illness and is caused by skeletal muscle injury resulting in the release of myoglobin and other cellular contents, including creatine kinase, into the circulatory system. Mild to moderate cases of acute exertional rhabdomyolysis can cause metabolic disorders including hypernatremia, hyperkalemia, hyperphosphatemia, hypocalcemia, lactic acidosis and hyperuricemia. Severe cases may result in renal failure and even death. Several case reports have been published since the early 1970s describing significant morbidity and mortality of acute exertional rhabdomyolysis in patients with SCT. We present the case of a 27-year-old male with a past medical history significant only for SCT who presented after a 1.5 mile run with severe exertional rhabdomyolysis and subsequent acute renal failure requiring hemodialysis (HD). In presenting this case, we hope to raise awareness of a possible underlying cause to many cases of exertional rhabdomyolysis and encourage physicians to counsel their patients with SCT in order to avoid the significant morbidity and mortality that may be associated with the condition.

Electrocardiographic T-wave changes underlying acute cardiac and cerebral events.

T-wave inversions produced by myocardial infarction (MI) are classically narrow and symmetric. Electrocardiography T-wave changes including low-amplitude and abnormally inverted T waves may be the result of noncardiac path physiology. We present a series of cases that presented with different electrocardiography T-wave changes. The first case involved a 64-year-old woman who presented to the emergency department with diffuse splayed T-wave inversions and was found to have an MI in the context of an acute cerebrovascular accident. We contrasted this case with that of a 76-year-old man with hypercholesterolemia who presented with T-wave widening and a prolonged QT interval and was found to have a subarachnoid hemorrhage secondary to a basilar aneurysm and no MI. Several mechanisms have been suggested to explain the cardiac and cerebral injury, including microvascular spasm and increased levels of circulating catecholamines. Accurate interpretation of T-wave changes can assist the clinician toward a timely therapeutic intervention and accurate diagnosis.

Persistent second-degree atrioventricular block following adenosine infusion for nuclear stress testing.

The agents used for nuclear stress testing (NST) including adenosine, dobutamine, and dipyridamole, are generally well tolerated and the incidence of serious complications associated with their use in NST is relatively low. Adenosine possesses a potent inhibitory effect on the atrioventricular (AV) node and may induce a transient conduction defect which could result in first-, second-, or third-degree heart block in some patients. The use of the potent AV nodal blocker adenosine for nuclear stress testing in patients with evidence of underlying conduction system disease may result in serious complications. We present the case of a 79-year-old man who had sustained second-degree AV block requiring permanent pacemaker implantation following adenosine infusion for nuclear stress testing. We also review the literature regarding the association between adenosine NST and AV block.

Planning and Guidance of Cardiac Resynchronization Therapy–Lead Implantation by Evaluating Coronary Venous Anatomy Assessed with Multidetector Computed Tomography

Objectives We sought to evaluate the utility of multidetector computed tomography (MDCT) in preoperative planning of cardiac resynchronization therapy (CRT) device implantation. Background Variation in coronary venous anatomy can affect optimal lead placement and may warrant preimplantation visualization prior to CRT lead placement. Methods Prospective randomized enrollment of 29 patients (17 males; mean age at implant 66.7 ± 12.8 years) was undertaken. Patients were randomized to preimplantation MDCT (GE® 64-detector Lightspeed, n = 16) or no MDCT. Implantation was planned based on three-dimensional coronary venous reconstruction as visualized in the CT group. Measurement of coronary sinus (CS) angulation, CS ostial (os) diameter, right atrial (RA) width, volume, and height was undertaken prior to implant. Intraoperative CS lead implantation times (introduction, cannulation, and left ventricular [LV] lead positioning), procedure time, fluoroscopy time, and venogram contrast volume were measured to determine if there was a difference between patients who underwent preimplant CT scan and those who did not. Results CS os diameter (mean = 13.8 ± 2.9 cm) was inversely correlated with total fluoroscopy time (r = -0.57, P = .008), and total procedure time, but this correlation was not statistically significant (r = - 0.36, P = 0.12). RA width (mean = 52.8 ± 9.9 cm) was associated with a shorter total procedure time (r = −0.44, P = .047) and LV lead positioning time (r = −0.33, P = .012). There were no statistically significant differences between the CT group and the non-CT group with respect to total intraoperative and fluoroscopy times or venogram contrast volumes. Total procedure time was longer in the CT group but the difference was not statistically significant (94 ± 27.2 vs. 74.7 ± 26.6; P = .065). Conclusion Noninvasive visualization of the coronary venous anatomy before CRT implantation can be used as a guide for lead placement. While no significant differences were noted between the two groups with respect to intraoperative variables, CS os diameter and RA width inversely correlated to a shorter procedure time and LV lead positioning time, respectively. Further clinical trials regarding the utility of MDCT to visualize coronary venous anatomy prior to CRT implantation for procedural planning and lead placement guidance are warranted.

Pacemaker ventricular lead microdislodgement following a motor vehicle accident

Pacemaker lead dislodgement can be defined as any lead position change, whether the functionality of the pacemaker is affected or not. Only dislodgements that provoke a malfunction in the pacing system, however, are clinically relevant. Lead dislodgement can be categorized as ‘macro’ or ‘micro’ dislodgement depending upon the presence of radiographic evidence. This case illustrates a case of lead microdislodgement after a low-impact motor vehicle accident. The lead tip was minimally displaced; enough to produce an increase in capture threshold and eventually loss of capture while keeping near normal lead impedance values. Review of the literature shows that ventricular lead dislodgement after a motor vehicle accident is a rare incidence and cause of pacemaker malfunction.

Emotion-Triggered Cardiac Asystole-Inducing Neurocardiogenic Syncope

The pathophysiology of neurocardiogenic syncope (NCS) is multifactorial. Recurrent syncopal episodes can result in injury and can provoke substantial anxiety among patients. Although an abundance of descriptions of various forms of syncope have been reported in the literature, few articles to date address a documented case due to emotional stress or sound. This is a report of a 31‐year‐old woman who fainted after being startled by someone sneezing. Review of the episode on her event recorder revealed a transient cardiac asystole of 10 seconds. We discuss the incidence of NCS and the proposed mechanism by which this syncopal event occurred.

Sudden cardiac death in a 20-year-old male swimmer.

In young adults, hypertrophic obstructive cardiomyopathy (HOCM) is an acknowledged risk factor for sudden cardiac death (SCD) in an otherwise healthy and active patient. While the incidence of SCD in young people is not high enough for extensive, wide-scale examinations, the potential for prevention of some deaths via pre-exercise imaging may be beneficial in certain patient populations, such as those with a family history of SCD or professional athletes. We present the case of a healthy 20-year-old man with no past medical history who died while swimming in a river, likely secondary to cardiac arrest in the setting of HOCM.

Rapid progression of atrioventricular nodal blockade in a patient with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a multisystem disorder with numerous potential adverse effects on the cardiovascular system. These complications likely develop in most patients with SLE at some time during the course of their disease, in part due to the decreased mortality associated with SLE as a result of modem medical management. Conduction disturbances have been reported in the literature to occur primarily from the progression of SLE and secondarily from pharmacotherapy used to treat SLE and may first be evident on the electrocardiogram in the emergency department (ED) setting. Electrocardiogram abnormalities such as borderline first-degree heart block may be clues to more significant cardiac disease brought upon by years of chronic inflammation, myocarditis, vasculitis, and fibrosis that are often the result of longstanding autoimmune disease. It is essential that patients with autoimmune disease be screened carefully in the ED setting for underlying myocardial disease, particularly given the increased potential for atherosclerosis, ischemia, arrhythmias, and myocardial conduction defects in these patients.

Echocardiographic predictors of ventricular tachycardia

Background Patients with structural heart disease are prone to ventricular tachycardia (VT) and ventricular fibrillation (VF), which account for the majority of sudden cardiac deaths (SCDs). We sought to examine echocardiographic parameters that can predict VT as documented by implantable cardioverter-defibrillator (ICD) appropriate discharge. We examine echocardiographic parameters other than ejection fraction that may predict VT as recorded via rates of ICD discharge. Methods Analysis of 586 patients (469 males; mean age = 68 ± 3 years; mean follow-up time of 11 ± 14 months) was undertaken. Echo parameters assessed included left ventricular (LV) internal end diastolic/systolic dimension (LVIDd, LVIDs), relative wall thickness (RWT), and left atrial (LA) size. Results The incidence of VT was 0.22 (114 VT episodes per 528 person-years of follow-up time). Median time-to-first VT was 3.8 years. VT was documented in 79 patients (59 first VT incidence, 20 multiple). The echocardiographic parameter associated with first VT was LVIDs >4 cm (P = 0.02). Conclusion The main echocardiographic predictor associated with the first occurrence of VT was LVIDs >4 cm. Patients with an LVIDs >4 cm were 2.5 times more likely to have an episode of VT. Changes in these echocardiographic parameters may warrant aggressive pharmacologic therapy and implantation of an ICD.