Supraventricular tachycardia (SVT) describes a rapid heart rate that begins in the heart’s upper chambers. A normal resting heart rate ranges from 60 to 100 beats per minute, but during an SVT episode, the heart can beat much faster, often between 150 and 220 beats per minute. This condition can arise suddenly and may be triggered by physical activity. This article explores whether exercise-induced SVT is dangerous and how it is managed.
Understanding Exercise-Induced SVT
SVT is an arrhythmia caused by faulty electrical signals in the heart’s upper chambers. Normally, the heart’s electrical impulse originates in the sinoatrial (SA) node, the natural pacemaker, and travels through the atria to the atrioventricular (AV) node, then to the ventricles. In SVT, an abnormal electrical pathway or circuit causes the signal to loop continuously or fire too quickly, leading to a sudden acceleration of the heartbeat.
Exercise can trigger SVT due to the body’s response to physical exertion. Increased adrenaline (catecholamines) during activity can speed up electrical conduction in the atria, activating latent abnormal pathways. For instance, atrioventricular nodal re-entrant tachycardia (AVNRT), the most common type of SVT, often becomes apparent when adrenaline levels peak. Common sensations during an SVT episode include a sudden racing heart, palpitations, shortness of breath, lightheadedness, or dizziness.
Evaluating the Severity of Exercise-Induced SVT
For many individuals, exercise-induced SVT is not considered life-threatening, though it can be uncomfortable. SVT’s danger varies based on factors, particularly the presence of underlying heart conditions. If there is no structural heart disease, the risk is generally low. However, if other heart issues such as coronary artery disease or cardiomyopathy are present, the risk can increase.
The type of SVT also influences its severity. For example, Wolff-Parkinson-White (WPW) syndrome involves an extra electrical pathway that can lead to very rapid heart rates during exercise and a higher risk.
Symptoms during an episode are an important indicator of severity. While mild symptoms like palpitations or dizziness are common, severe symptoms such as chest pain, severe shortness of breath, or fainting (syncope) require immediate medical attention. Fainting, in particular, may signal insufficient blood flow to the brain and can triple the odds of an underlying structural heart problem. The duration and frequency of episodes also play a role, as sustained episodes might lead to complications.
Diagnosing and Managing Exercise-Induced SVT
Diagnosing exercise-induced SVT begins with a review of medical history and a physical examination, inquiring about symptoms and their triggers. An electrocardiogram (ECG or EKG) is a primary test to check the heart’s electrical activity, ideally during an episode. If episodes are infrequent, a Holter monitor or event recorder may be used to capture the heart’s activity over a longer period.
An exercise stress test can be performed to trigger and observe SVT in a controlled environment. An echocardiogram or other imaging may assess the heart’s structure and rule out underlying issues. For a more detailed understanding of the heart’s electrical pathways, an electrophysiology (EP) study can be conducted, guiding catheters into the heart to map electrical signals and identify the source of the arrhythmia.
Management strategies for SVT depend on the frequency and severity of episodes. Acute episodes can be stopped using vagal maneuvers, such as bearing down (Valsalva maneuver) or splashing cold water on the face, to slow the heart rate. In a medical setting, medications like adenosine may be administered to quickly restore a normal rhythm.
Long-term management may involve medications such as beta-blockers or calcium channel blockers to prevent or slow down episodes. For a definitive solution, catheter ablation is a procedure that uses energy to create small scars in the heart tissue, disrupting the abnormal electrical pathways responsible for SVT. This procedure has a high success rate for many types of SVT. When episodes are infrequent and mild, if serious conditions are ruled out, a watchful waiting approach may be used.
Living Actively with Exercise-Induced SVT
Many individuals with exercise-induced SVT can safely maintain an active lifestyle with appropriate guidance. Consulting a cardiologist or electrophysiologist before resuming strenuous exercise after an SVT diagnosis is important. They can provide personalized exercise recommendations based on the specific type of SVT, its triggers, and any underlying heart conditions.
Gradual return to activity is advised, beginning with moderate-intensity exercises like brisk walking or cycling. Individuals may learn to identify and avoid triggers, such as excessive caffeine, certain stimulants, or extreme dehydration, if they consistently trigger episodes. Proper warm-up and cool-down periods can help prevent sudden changes in heart rate that might trigger SVT. Monitoring symptoms and knowing when to stop exercising is important. Adherence to prescribed medications or post-ablation care is key to safe and continued physical activity.