Asking what is the heart disorder/condition? ECG showed no P Wave

Question

A young woman was at the gym doing great her normal workout. She would spend 45 minutes on the elliptical and then 15 minutes doing weight training. This was the regular routine for her as she did this almost everyday. One day her normal routine turned upside-down. As she finished her elliptical workout and was making her way to the weight machines, she experienced a rapid heart beat. This washould nothing alarming at first because she had experienced this rapid heart beat before. When it happened previously the rapid heartbeat lasted only 10 or 20 seconds. However, this time was different. She experienced the rapid heart beat, but this time the heart beat did not slow down after 20 seconds. The rapid heart beat continued and she began to feel shortness of bread, some pressure I her chest, as well as feeling light-headed. Scared for what might be happening in general she went home called her husband. Frantically she tried to explain how she was feeling and how scared she was. They went to the E.R during her sTay in the ER her heart rate was constantly monitored. For five hours her heart rate remained between 130 and 150 bpm. After 5 hours her heart rate spontaneously returned to a normal rhythm. She was kept overnight In the ER and attending cardiologist prescribed low-dose beta-blockers

She was given a number of different test and the results were:
-blood pressure normal
- hematocrit normal
-cholesterol normal

She is 34 mother of two. She is of adequate weight and BMI for her age and height. She has regular wellness checkups every year and has never had high cholesterol or hypertension.

Answer 1

The first big clue is in your heading. "The ECG showed no p wave." We don't know what else the ECG looked like except that the rate was 130-150, which by definition is tachycardia (anything over 100). Given her age (34), heart rate, symptoms, and presuming she is otherwise healthy, this woman likely experienced supraventricular tachycardia (SVT). This is a way of saying the tachycardia originates above the ventricles, though we may not be sure exactly where. If she experienced ventricular tachycardia she would have lost consciousness and been in far worse shape.

 

This woman's symptoms are typical of SVT. The lightheadedness, chest pressure and shortness of breath are indicative of decreased cardiac output due to the fast heart rate, which may have been made worse by the fact that the rhythm apparently didn't originate in the SA node (no p waves). This would cause a reduction in cardiac output by 30% due to the loss of atrial kick. Her fast heart rate reduces ventricular filling time and blood flow to the coronary arteries, which in turn reduces oxygen supply to the cardiac muscle, causing chest pain.

 

There are several different types of supraventricular tachycardia, but I would venture a guess that this woman had what is called paroxysmal (sudden onset) supraventricular tachycardia (PSVT) due to her young age, health status (apparently pretty good since she is working out at the gym), similar symptoms in the past, and sudden onset. The fact that the woman stayed overnight in the ER, rather than being admitted to the ICU, suggests a benign type of tachycardia such as PSVT. Also, the fact that she was treated with low-dose beta blockers is suggestive of PSVT.