Physical Address

304 North Cardinal St.
Dorchester Center, MA 02124

Myocardial Ischemia and Infarction, Part I: ST Segment Elevation and Q Wave Syndromes

This chapter and the next examine one of the most important topics in electrocardiogram (ECG) analysis and clinical medicine, namely the diagnosis of myocardial ischemia and infarction (ischemic heart disease), a a The terms infarction and infarct are used interchangeably in this book and in clinical practice. including ST segment elevation myocardial infarction (STEMI). We begin with basic concepts and terms. Myocardial Ischemia and Infarction: General…

Ventricular Conduction Disturbances: Bundle Branch Blocks and Related Abnormalities

Recall that in the normal process of ventricular activation the electrical stimulus (signal) reaches the ventricles from the atria by way of the atrioventricular (AV) node and His–Purkinje system ( 1, 5 ). The first part of the ventricles to be stimulated (depolarized) is the left side of the ventricular septum. Soon after, the depolarization spreads simultaneously to the main mass of the left and right…

Atrial and Ventricular Overload/Enlargement

The first six chapters have been devoted to the basics of electrocardiograms (ECGs). From this point on, we focus attention primarily on the recognition and understanding of abnormal ECG patterns. This chapter discusses the ECG manifestations of enlargement and related abnormalities of the four cardiac chambers. As a prelude, we emphasize that in the detection of cardiac chamber size the ECG offers only an indirect assessment.…

Electrical Axis and Axis Deviation

Normal electrocardiogram (ECG) patterns in the chest and extremity leads were discussed in Chapter 5 . The general terms horizontal heart (or horizontal QRS axis ) and vertical heart (or vertical QRS axis ) were used to describe normal, individual variations in QRS patterns seen in the extremity leads. The purpose of this chapter is to further refine the concept of electrical axis and to present methods…

The Normal Electrocardiogram

The previous chapters reviewed the cycles of atrial and ventricular depolarization/repolarization detected by the electrocardiogram (ECG) and the standard 12-lead system used to record this electrical activity. This chapter describes the detailed appearance of the P–QRS–T patterns seen normally in these 12 leads. Fortunately, you do not have to memorize 12 or more separate patterns. Rather, understanding basic principles about the timing and orientation of cardiac…

Electrocardiogram Leads

As discussed in Chapter 1 , the heart produces electrical currents similar to the dry cell battery. A special recording instrument (sensor) such as an electrocardiograph can measure the strength or voltage of these currents and the way they are transmitted throughout the body over time. The body acts as a conductor of electricity. Therefore recording electrodes placed some distance from the heart, such as on the…

How to Make Basic ECG Measurements

This chapter continues the discussion of electrocardiogram (ECG) basics introduced in 1, 2 . Here we focus on recognizing key components of the ECG in order to make clinically important measurements from these time–voltage graphs. Standardization (Calibration) of the ECG The standard ECG recording is generally calibrated such that a signal of 1-mV amplitude produces a 10-mm deflection. Modern ECG units are electronically calibrated; older ones…

Electrocardiogram Basics: Waves, Intervals, and Segments

The first purpose of this chapter is to present two fundamental electrical properties of heart muscle cells: (1) depolarization (activation) and (2) repolarization (recovery). Second, in this chapter, and the next, we define and show how to measure the basic waveforms, segments, and intervals essential to electrocardiogram (ECG) interpretation. Depolarization and Repolarization In Chapter 1 , the term electrical activation (stimulation) was applied to the spread of…

Essential Concepts: What Is an ECG?

The electrocardiogram ( ECG or EKG ) is a special type of graph that represents changes in cardiac electrical activity from one instant to the next. Specifically, the ECG provides a time-voltage chart of the heartbeat. 10 seconds of ECG data (lead II) from healthy young adult. Note variation in rate due to breathing. Open full size image The ECG is a key component of clinical diagnosis…

Transesophageal Echocardiography for Cardiac Surgery

Introduction Transesophageal echocardiography (TEE) for intraoperative planning is well established in the armamentarium of surgeons, cardiologists, and anesthesiologists. The use of intraoperative TEE has become the standard of care during cardiac surgery, and the intraoperative echocardiographer (IE), generally an anesthesiologist, has become an integral part of the cardiac surgery care team. This chapter will review the role of the IE and the intraoperative examination. Role of…

Echocardiography in the Context of Other Cardiac Imaging Modalities

Introduction Despite advances in imaging technology over the past 20 years, echocardiography has maintained its central role in cardiovascular medicine. Although some of this relates to the fact that echocardiographic technology is also progressing steadily, the primary reason is by virtue of the unique advantages of echocardiography including portability, rapid availability, safety, and excellent temporal resolution. As a result, echocardiography is generally the first tool implemented…

Appropriate Use of Echocardiography

Introduction Echocardiography is an important tool in the diagnosis and management of cardiovascular disease. The detailed cardiac structural and functional information that echocardiography provides, coupled with its portability and lack of ionizing radiation, has established this imaging modality as a critical tool in the care of patients with known or suspected cardiovascular disease. However, there has been concern in recent years regarding the rapid growth of…

Handheld Echocardiography

Introduction Although Moore’s law of increasing computing capabilities (including processing power and memory) has propelled the development of all imaging modalities, its most tangible manifestation has been in the field of ultrasonography. Unrestrained by the physical limitations (gantry size and power requirements) of the other modalities, echocardiography machines have evolved from large, cumbersome pieces of equipment to handheld echocardiography (HHE) devices that are the size of…

Other Common Congenital Defects in Adults

Introduction Due to improvements in surgical techniques and medical therapies in recent years, there has been an increase in survival to adulthood in those with complex congenital heart disease. While complex congenital heart disease requires a careful and individualized approach, there are some fundamental assessments that should occur based on anatomic diagnosis. Segmental Anatomy In patients with complex congenital heart disease, it is important to first…

Ventricular Septal Defect

Introduction Ventricular septal defects (VSDs) represent the most common type of congenital heart disease in childhood (∼40%). As a significant proportion of VSDs spontaneously close in childhood (predominantly muscular defects), the prevalence in adulthood decreases and is closer to 25%. Adult Presentation Most commonly, VSDs are diagnosed in childhood. Often, large VSDs are diagnosed due to recurrent infections or evidence of over-circulation, while small VSDs often…

Atrial Septal Defect

Introduction Atrial septal defects (ASDs) occur in 0.1% of the population and represent the largest group of congenital defects in the adult population. Echocardiographic evaluation of ASDs should include characterization of the defect, evaluation for additional associated lesions, and description of the physiologic effect of the ASD. Here we characterize a standardized approach as well as highlight some common pitfalls. Anatomy/Embryology Atrial septation occurs early in…

Echocardiography in Malignant Disease

Introduction Approximately two out of every five people will be diagnosed with cancer at some point during their lifetime. Significant improvements in cancer care have improved 5-year survival for all cancer sites from 49% in 1980 to 67% currently, such that there are over 14 million people living with cancer in the United States today. Multiple factors contribute to an increasing prevalence of clinically significant cardiotoxicity…

Other Systemic Diseases and the Heart

Introduction While echocardiography is, of course, critical in the evaluation of primary diseases of the heart, it is an equally important tool in identifying and monitoring the cardiovascular sequelae of systemic diseases and their treatment. Many of these are discussed in variable detail in prior chapters including those on dilated cardiomyopathies (see Chapter 22 ), Restrictive Cardiomyopathies (see Chapter 24 ), Mitral Valve Disease (see Chapter…