Case
Thanks for taking my call. I have this 16-year old adolescent male that I have been following for years who now presents for his athletic participation physical. As I am listening to his heart I am noting some skipped beats at rest. I don’t recall ever hearing this before and I have nothing documented in his chart. He is completely asymptomatic and wants to play basketball this year and is trying out for the varsity team in a few weeks. He has been practicing regularly and has not had any symptoms. I think he should be fine but I’m a little nervous about clearing him with these extra beats. My plan is to send him for an ECG but I’m wondering if you would suggest anything else?
What am I thinking?
It would be good to characterize the type of extra beats or irregular rhythm that the doctor has noted and so an ECG is a good start. An irregular rhythm in a teen is usually the result of either prominent sinus arrhythmia, or else frequent ectopic beats more commonly due to premature ventricular contractions (PVC) and less commonly, premature atrial contractions (PAC). The question is then to determine if these are benign or the sign of something more malignant. Sinus arrhythmia refers to the prominent irregularity of sinus beats often seen in the young and related to the respiratory cycle. It is an entirely normal phenomenon and is diagnosed by a rhythm strip or ECG monitor showing that the beats are sinus in origin (similar looking p waves) but with a significant irregularity that waxes and wanes on the recording (see Fig. 8.1 ). Since it is a normal finding, all that is needed is reassurance. PACs that occur singly are not uncommon. Being frequent enough to be noticeable to a listening nurse or doctor is, however, surprisingly rare. They are generally benign and do not need further evaluation or management (see Fig. 2.2 ). PVCs are the most common cause of an obviously recognizable irregular heart rhythm in teenagers.
| Differential diagnosis |
| Likely |
| Premature ventricular contractions Normal sinus arrhythmia |
| Possible |
| Premature atrial contractions Premature junctional beats “Echo” beat from reentry |
| Rare |
| Intermittent AV block Atrial fibrillation |
A thorough history and physical can often find clues to provide a better context for these types of arrhythmias. Additional testing may be helpful including long-term monitoring and ruling out of structural heart disease by an echocardiogram. In most cases, premature ventricular contractions are benign in a healthy young person but obtaining some additional evidence to support that contention is necessary.
History and physical
Often in the case of an adolescent patient with premature ventricular contractions, the history and physical are entirely normal. History should be focused on any history of palpitations or syncope, particularly with activity. Family history should be thoroughly obtained to help guide toward a potential diagnosis of genetic arrhythmia syndrome. A review of the patient’s dietary habits may be helpful, particularly the use of caffeinated beverages or energy drinks as these may lead to more ectopic beats. A review of medications is also important, particularly those that may result in electrolyte shifts (e.g., diuretics). Finally, the use of illicit drugs (steroids, cocaine, stimulants, etc.) may result in cardiac stress that could present with ectopic beats.
Physical examination is focused on cardiac findings to suggest cardiac disease. Auscultation of murmur may suggest structural heart disease though typically, the cardiac examination is normal with the exception of the ectopic beat upon auscultation. Changing the position of the patient from supine, to standing, to squatting may help elicit ectopic beats. Most often, the ectopic beats are noted while at rest. A reassuring sign is the suppression of ectopic beats with an increase in heart rate. Asking the patient to perform a physical activity such as jogging in place or jumping jacks in the office and then auscultating the heart again may show that the ectopic beats have gone away.
Diagnostic testing
Depending on the frequency of the ectopic beats, an ECG will be most helpful to identify the type and potential origin of the ectopic beat. PVCs have a distinct morphology suggesting the location of origin. On occasion, these PVCs may have more than one morphology and can be clearly delineated by changes in all of the ECG leads. Usually, a rhythm strip is required to capture enough of the PVCs that provides a comparison.
A 24-h Holter monitor is a good test to determine the frequency of the PVCs that can be helpful to determine additional steps required. Additionally, having the patient perform exercise during the Holter monitor provides the treating physician with a surrogate exercise stress test to demonstrate if PVCs increase with activity. Otherwise, a more traditional exercise stress test can be performed. For those patients who are symptomatic with their PVCs, it is recommended to keep a symptom diary with the Holter or use a cardiac event monitor to capture a single lead or multi-lead recording.
Blood chemistry to evaluate for electrolyte changes that may induce the PVCs is also recommended but is generally normal. In the setting of newly diagnosed PVCs, it is not unusual for an echocardiogram to be performed to evaluate for potential structural heart disease but also to evaluate for cardiac function. However, an echocardiogram is not always needed. A normal cardiac physical examination and normal appearance to the non-PVC sinus beats may be sufficient in many patients and echocardiography in such patients is of low yield. The real importance of echocardiography is in patients with a high (usually 20% or greater) PVC burden. PVC burden refers to the percentage of total beats that are due to PVCs. This number can be derived by Holter monitoring. Patients with a high burden may go on to develop ventricular dysfunction that is labeled as PVC-induced cardiomyopathy.
If history and physical are pointing to more concerning structural disease, a cardiac MRI may be helpful to evaluate for a scar related to hypertrophic cardiomyopathy or arrhythmogenic right ventricular cardiomyopathy.
Action plan
All young athletes who are noted to have premature ventricular contractions should be evaluated by a pediatric cardiologist. In most cases, these forms of arrhythmia are considered benign and do not pose any threat to the patient or their physical activity. However, there are some occasions where ventricular beats noted during activity may be the first sign of cardiovascular disease. Patients should undergo an ECG and Holter monitor at minimum. An echocardiogram could be considered if physical examination or the non-PVC sinus beat morphology is abnormal or if the PVC burden on Holter is high.
Depending on the results of the initial workup, further workup may be required. The asymptomatic young athlete with a structurally normal heart, normal cardiac function, and negative family history is likely to have benign ventricular ectopy. Benign ectopy is further supported with monomorphic morphology and low frequency that suppresses at higher heart rates.
Yet another important finding that supports a diagnosis of benign PVC is a patient who satisfies the above criteria and also has a characteristic morphology of PVCs that suggests that they arise from the right or left ventricular outflow tract (see Fig. 15.1 ). The characteristic pattern is one of PVCs with a left bundle branch block type of morphology with positive waves in leads II, III, and aVF, which suggest a high cardiac origin.
