Occasional Rapid Heartbeat (150 - 170) lasting four to six hours

When I get up in the morning I sometimes experience feeling of lightheadedness. This has happened eight times in the past year. The episodes last four to six hours and are very frightening. The doctor has not found anything wrong with me yet. He told me to take my pulse the next time it happened. To make sure I got it right I bought a blood pressure machine, which showed normal blood pressure, but a heart rate of 150 to 170. Once my heart rate went below 100, which took four hours, I felt fine. I feel awful for the whole four hours, but the lightheadedness fades in and out. There may be about 100 of these periods of lightheadedness, with each lasting about 30 seconds. I habitually hyperventilate when feeling lightheaded. There is no difference between standing and sitting, but I feel better if I go outside and take a brisk walk. When I am walking I do not get the lightheadedness, but it starts again when I come inside. There is nothing wrong with my home, since I have had these spells in several different cities. I am a male 75 years old and in generally good health.

Thanks, Kitt. I did not start keeping a journal until the last bout of tachycardia. I was unsure if I was counting my pulse properly, so I bought a blood pressure machine. I have a very thorough record of what happened during the last bout in terms of blood pressure and pulse. The doctor wants me to have an EKG while I am having a bout, but I can't see how that would be possible, since it is all over in about four hours. He's going to give me an echo cardiogram for whatever insights that might offer. I just have the sense that this problem has some simple explanation and solution, since it happens only rarely and does not last long. I find it curious that I feel better simply going for a brisk walk. I read that a deficiency of carbon dioxide can bring on tachycaria, and a brisk walk would tend to increase carbon dioxide in the blood. I am also wondering if it might be caused by eating a big meal before retiring and perhaps not enough fluid. This always happens when I get up in the morning, so it is not something triggered by something I was doing when it happened.

Thanks again for your interest and sympathy, Kitt.

There is a thread at the top of this page with info on "heart attacks and symptoms"

Common signs and symptoms of a heart attack include:

Pressure, fullness or a squeezing pain in the center of your chest that lasts for more than a few minutes
Pain extending beyond your chest to your shoulder, arm, back, or even to your teeth and jaw
Increasing episodes of chest pain
Prolonged pain in the upper abdomen
Shortness of breath
Sweating
Impending sense of doom
Fainting
Nausea and vomiting
Signs and symptoms of a heart attack in women may be different or less noticeable than heart attack symptoms in men. In addition to the symptoms above, heart attack symptoms in women can include:

Abdominal pain or "heartburn"
Clammy skin
Lightheadedness or dizziness

Unusual or unexplained fatigue

Not all people who have heart attacks experience the same ones or experience them to the same degree. Many heart attacks aren't as dramatic as the ones you've seen on TV. Some people have no symptoms at all. Still, the more signs and symptoms you have, the greater the likelihood that you may be having a heart attack.

A heart attack can occur anytime — at work or play, while you're resting, or while you're in motion. Some heart attacks strike suddenly, but many people who experience a heart attack have warning signs and symptoms hours, days or weeks in advance. The earliest predictor of an attack may be recurrent chest pain (angina) that's triggered by exertion and relieved by rest. Angina is caused by temporary, insufficient blood flow to the heart, also known as "cardiac ischemia." reference: Mayo Staff

Don't "tough out" the symptoms of a heart attack, such as pressure or pain in your chest, for more than five minutes. Call 911 or other emergency medical services for help. If you don't have access to emergency medical services, have someone drive you to the nearest hospital, such as a neighbor or friend. Drive yourself only as a last resort, if there are absolutely no other options. Driving yourself puts you and others at risk if your condition suddenly worsens.

A heart attack generally causes uneasiness or ache in the middle of chest. The ache may come on swiftly, or now and then it may begin gradually, developing in intensity in a matter of minutes. It may feel like pressure, squeezing, fullness, heaviness or tightness. The pain has been depicted by patients as: 'like an elephant sitting on my chest', 'like a red hot poker in the centre of my chest' or 'like a steel band tightening around my chest'. The ache might be mild, severe or even moderate.
 

Please remember I am not a physician.