Chapter 33

An exercise stress test challenges the heart to respond to the increased demands of exercise in a controlled and monitored environment. Not only do exercise stress tests show changes in heart rate, blood pressure, and perceived level of exercise, but they have also been found useful in determining what?

ECG ischemic-type ST-segment changes

A Holter monitor is a small ECG recording devise used for long-term monitoring of cardiac activity, usually for up to 48 hours. These devices are used in correlation with event markers (on the device itself) and activity logs, or diaries of the person's activities. What cardiac problems is a Holter monitor useful in documenting?

Conduction abnormalities ST-segment changes

In children, what is sick sinus syndrome most commonly associated with?

Congenital heart defects following corrective cardiac surgery.

Brugada syndrome, an autosomal dominant disorder, manifests in adulthood as ST-segment elevation, right bundle branch block, and susceptibility to ventericular tachycardia. In Brugada syndrome, the timing of cardiac events is significant. When do these cardiac events typically occur?

During sleep or rest

ECG monitoring has been found to be more sensitive than a patient's report of symptoms when identifying transient ongoing myocardial ischemia. Why is this?

Most ECG-detected ischemic events are clinically silent.

Respiratory sinus arrhythmia is considered a more optimal rhythm than a rhythm where all RR intervals are equal. In respiratory sinus arrhythmia, what is the variation in cardiac cycles related to?

Intrathoracic pressure changes that occur with respiration

When a patient has a recurrent, life-threatening arrhythmia originating either suprventricularly or ventricularly, ablation therapy is an option for treatment. What does ablation therapy do?

Isolates and destroys arrhythmogenic cardiac tissue.

Atrial fibrillation is the most common chronic arrhythmia whose incidence increases with age. Atrial fibrillation may present as asymptomatic to severe symptomatology. What is the treatment of atrial fibrillation dependent on?

Recency of onset Etiology Persistence of arrhythmia

Torsade de pointes is a specific type of polymorphic ventricular tachycardia in which the polarity of the QRS complex swings between positive and negative, often on a beat-to-beat basis. It is the result of the long QT syndrome and can cause sudden cardiac death. Which medication is not linked to torsade de points as a causative?

Tetracycline

In second-degree atrioventricular block, there is a relationship between the P waves and the QRS complex resulting in recurring PR intervals. What does that mean?

The association of P waves and QRS complexes is not random.