Wednesday, June 22, 2016

64-Year-Old Woman Presents with a Severe Dilated Cardiomyopathy and HF

A 64-year-old woman who presents with a severe dilated cardiomyopathy and heart failure. She is clinically stable, although experiencing mild dyspnea on exertion. What does the ECG show?


Response: Regarding the 64-year-old woman who presents with a severe dilated cardiomyopathy and heart failure.

Diagnosis: normal sinus rhythm, intraventricular conduction delay (cardiomyopathic QRS complex), left anterior fascicular block

There is a regular rhythm at a rate of 84 bpm. There is a P wave before each QRS complex with a constant PR interval (0.16 sec). The P wave is positive in leads I, II,  aVF, and V4-V6. Hence this is a normal sinus rhythm. The QRS complexes are wide (0.16 sec) and there is a morphology that resembles a left bundle branch block with a deep S wave in lead V1 (→) and a broad R wave in leads I and V6 (←). However, there are certain findings which are not seen with a left bundle branch block, particularly septal forces (i.e. small Q waves in leads I, aVL, V6 and septal R wave in lead V1). This is because the septal or medial fascicle which innervates the septum arises from the left bundle. The septum is the first part of the left ventricle to be depolarized and it is activated in a left to right direction, accounting for the small septal Q waves in leads I, aVL, and V6 and the septal R wave in lead V1. In this case, there are septal Q waves in leads I and aVL (^) and a septal R wave in lead V1 (v). Therefore this is not a left bundle branch block but rather a nonspecific intraventricular delay. Other findings not seen with a left bundle branch block are any left to right forces (terminal S wave in leads I and V6) and a right axis. With an intraventricular conduction delay left ventricular activation goes through the normal His-Purkinje system, but is slow. Since left ventricular activation is via the normal conduction system, abnormalities affecting the left ventricle can be diagnosed. In contrast, with a left bundle branch block left ventricular activation is via direct myocardial activation from the right ventricle and not the normal conduction system. Therefore abnormalities affecting the left ventricle cannot be reliably diagnosed. The axis is extremely left between -30° and -90° (positive QRS complex in lead I and negative complex in leads II and aVF). The two etiologies for an extreme left axis are an old inferior wall myocardial infarction in which there are Q waves in leads II and aVF or a left anterior fascicular block with an rS morphology in leads II and aVF. In this case, this is a left anterior fascicular block which can be diagnosed since there is no left bundle branch block. The QT/QTc intervals are prolonged (460/545 msec) and still slightly prolonged when corrected for the prolonged QRS complex duration (400/ 470 msec). When the QRS is this wide due to an intraventricular conduction delay there is likely an underlying dilated cardiomyopathy, i.e. this is a cardiomyopathic looking QRS complex. The last two QRS complexes (*) are wide (0.16 sec) and have a different morphology; they are not preceded by a P wave. These are premature ventricular complexes. Two in a row is often referred to as a ventricular couplet.


Monday, June 13, 2016

CME: Resuscitation Science

CME COURSE
Survival Analysis After Extracorporeal Membrane Oxygenation in Critically Ill Adults

Abstract
Background
—Extracorporeal membrane oxygenation (ECMO) provides circulatory and respiratory support for patients with severe acute cardiopulmonary failure. The objective of this study was to examine the survival outcomes for patients who received ECMO.
Methods and Results—Adult patients who received ECMO from September 1, 2002, to December 31, 2012, were identified from the Taiwan National Health Insurance Database associated with coronary artery bypass graft surgery, myocardial infarction/cardiogenic shock, injury, and infection/septic shock. A Cox regression model was used to determine hazard ratios and to compare 30-day and 1-year survival rates with the myocardial infarction/cardiogenic shock group used as the reference. The mean±SD age of the 4227-patient cohort was 57±17 years, and 72% were male. The overall mortalities were 59.8% and 76.5% at 1 month and 1 year. Survival statistics deteriorated sharply when ECMO was required for >3 days. Acute (30-day) survival was more favorable in the infection/septic shock (n=1076; hazard ratio, 0.61; 95% confidence interval, 0.55–0.67), coronary artery bypass graft surgery (n=1077; hazard ratio, 0.68; 95% confidence interval, 0.61–0.75), and injury (n=369, hazard ratio, 0.82; 95% confidence interval, 0.70–0.95) groups. The extended survival rapidly approached an asymptote near 20% for the infection/septic shock, myocardial infarction/cardiogenic shock (n=1705), and coronary artery bypass graft surgery groups. The pattern of survival for the injury group was somewhat better, exceeding 30% at year-end.
Conclusions—Regardless of initial pathology, patients requiring ECMO were critically ill with similar guarded prognoses. Those in the trauma group had somewhat better outcomes. Determining the efficacy and cost-effectiveness of ECMO should be a critical future goal.

Thursday, June 9, 2016

65-Year-Old Man with History of Chronic Stable Angina

A 65-year-old man with a history of chronic stable angina who presents to the emergency room with a 2-hour history of epigastric discomfort radiating to his left shoulder and arm. He also complains of nausea.



Response: Regarding the 65-year-old man with a history of chronic stable angina, epigastric discomfort radiating to his left shoulder and arm with nausea.

Diagnosis: sinus tachycardia, first degree AV block (AV delay), acute inferior wall ST segment elevation myocardial infarction, possible posterior wall infarction

There is a regular rhythm at a rate of 100 bpm. There is a P wave before each QRS complex (+) with a constant PR interval (0.26 sec). The P wave is positive in leads I, II, aVF, and V4-V6. Therefore this is a sinus tachycardia with a first degree AV block or first degree AV delay. The QRS complex duration is normal (0.08 sec) and there is a normal morphology and normal axis between 0° and +90° (positive QRS complex in leads I and aVF). The QT/QTc intervals are normal (360/465 msec). There is ST segment elevation in leads II, III, and aVF (↓) consistent with a current of injury and an acute inferior wall ST segment elevation myocardial infarction. Although there are small Q waves in these leads (▲) they are narrow (<0.04 sec in duration) and not pathologic. There is ST segment depression in leads I and aVL (^), which are the reciprocal changes seen with an acute inferior wall ST segment elevation infarction. There are also ST segment depression in leads V1-V2 (↑), which may be reciprocal but are more likely due to posterior wall involvement. This should be evaluated further by recording posterior leads (V7-V8) placed under the left scapula.