Conditions · Houston
A heart that runs too slow and a heart that runs too fast are opposite problems with different causes, different urgency, and different treatments. Some people have both.
Bradycardia is a heart rate below about 60 beats per minute. On its own that number means very little — trained athletes sit in the 40s and are entirely well. It matters when it is too slow for what you are doing, and when symptoms line up with it.
Two mechanisms account for most of it. In sinus node dysfunction, the heart’s own pacemaker fires too slowly or pauses. In heart block, the sinus node works but the signal is delayed or blocked on its way to the ventricles.
The distinction between Mobitz I and Mobitz II is not academic. It changes urgency substantially, and it is a reason to have the tracing read by someone who looks at these all day.
Tachycardia is a rate above about 100. What matters is where it originates. Supraventricular rhythms start above the ventricles — SVT, atrial fibrillation, atrial flutter. They are often very treatable and frequently curable with ablation.
Ventricular rhythms start in the lower chambers and carry more urgency, particularly when the heart muscle is already weakened. A fast rhythm with fainting, chest pain, or severe breathlessness is an emergency regardless of where it starts.
Tachycardia-bradycardia syndrome is a recognized pattern: a fast atrial rhythm stops, and the sinus node — suppressed and slow to recover — leaves a long pause before the next beat. People describe racing followed by a near-faint.
It creates a genuine bind, because the medication that controls the fast rhythm worsens the slow one. Resolving it often means treating each half on its own terms rather than accepting a compromise that handles neither well.
Thyroid disease. Electrolyte abnormalities. Sleep apnea. Medications — beta blockers, calcium-channel blockers, and several others slow conduction, sometimes by design and sometimes further than intended. Anemia, infection, and dehydration drive rates up.
Some of these are reversible. Implanting a device for a rhythm caused by a medication that could be adjusted is a poor outcome, and it is avoidable by looking first.
The same principle as any rhythm problem: record it while you feel it. An ECG, then ambulatory monitoring matched to how often symptoms occur — a Holter, a patch, or an implantable loop recorder when events are rare or fainting is unexplained.
For symptomatic bradycardia that is not reversible, a pacemaker is the treatment, and conduction-system pacing can preserve a more natural contraction than conventional pacing. For fast rhythms, the options are medication, catheter ablation to treat the circuit directly, and — where the risk is a dangerous ventricular rhythm — a defibrillator.
Procedures are performed at Houston Methodist, Memorial Hermann, Baylor St. Luke’s, and HCA hospitals across the Texas Medical Center, Clear Lake, and Pearland corridors. Clinic follow-up is at TMC, Clear Lake, or Pearland, Monday–Friday, 8am–5pm. One number: (832) 972-7300.
Dr. Boone evaluates you, performs the procedure, and keeps the follow-up. There is no hand-off to a different physician for the part that matters.
Not necessarily. Fit people and many people during sleep run in the 40s with no difficulty. It matters when it fails to rise with exertion, or when it comes with fatigue, lightheadedness, or fainting.
No. The first step is finding out whether something reversible is causing it — medication, thyroid, sleep apnea. A pacemaker is for symptomatic slowing that is not going to correct itself.
In a structurally normal heart it is usually not life-threatening, though it can be genuinely debilitating. It is also one of the most curable rhythms in electrophysiology, which is a good reason to have it identified.
Where the block sits and what it predicts. Mobitz I is typically higher in the conduction system and often benign. Mobitz II sits lower, drops beats without warning, and is taken more seriously because it can progress.
Usually within the week. No referral is required. Call (832) 972-7300, or fax records to (855) 538-7649.
Related: Pacemakers & ICDs · All arrhythmias · Atrial fibrillation · All conditions
Both start the same way: a recorded tracing, read by someone who does this all day.
