What Is a Normal Heart Rhythm?

The heart has four areas, or chambers. During each heartbeat, the two upper chambers (atria) contract, followed by the two lower chambers (ventricles). This is directed by the heart's electrical system.

The electrical impulse begins in an area called the sinus node, located in the right atrium. When the sinus node fires, an impulse of electrical activity spreads through the right and left atria, causing them to contract, forcing blood into the ventricles.

Then the electrical impulses travel in an orderly fashion to areas called the atrioventricular (AV) node and HIS-Purkinje network. The AV node is the electrical bridge that allows the impulse to go from the atria to the ventricles. The HIS-Purkinje network carries the impulses throughout the ventricles. The impulse then travels through the walls of the ventricles, causing them to contract. This forces blood out of the heart to the lungs and the body. The pulmonary veins empty oxygenated blood from the lungs to the left atrium. A normal heart beats in a constant rhythm -- about 60 to 100 times per minute at rest.

What Is Atrial Fibrillation?

Atrial fibrillation (also referred to as AF or Afib) is the most common type of irregular heartbeat. It is found in about 2.2 million Americans. Its frequency increases with age. If you have AF, the electrical impulse does not travel in an orderly fashion through the atria. Instead, many impulses begin simultaneously and spread through the atria and compete for a chance to travel through the AV node.

The firing of these impulses results in a very rapid and disorganized heartbeat. The rate of impulses through the atria can range from 300 to 600 beats per minute. Luckily, the AV node limits the number of impulses it allows to travel to the ventricles. As a result, the pulse rate is often less than 150 beats per minute, but this is often fast enough to cause symptoms.

What Are the Symptoms of Atrial Fibrillation?

You may have atrial fibrillation without having any symptoms at all. If you have symptoms, they may include:

• Heart palpitations (a sudden pounding, fluttering, or racing feeling in the chest)
• Fatigue or lack of energy
• Dizziness (feeling faint or light-headed)
• Chest discomfort (pain, pressure, or tightness in the chest)
• Shortness of breath (difficulty breathing during normal activities or even at rest)

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Learn about some of the many types of sexual conditions.

Sexual Performance Anxiety

Sex is supposed to be a pleasurable experience, but it's hard to feel sexy or intimate with your partner when you have sexual performance anxiety.

Inability to Orgasm

About 10% of women have never had an orgasm -- either with a partner or during masturbation.

Paraphilias

Paraphilias are problems with controlling impulses that are characterized by recurrent and intense sexual fantasies, urges, and behaviors involving unusual objects, activities, or situations not considered sexually arousing to others.

Trichomoniasis

Trichomoniasis is a sexually transmitted disease (STD) caused by a small organism called Trichomonas vaginalis.

Genital Warts and HPV

Human papillomavirus or HPV is an easily transmitted virus that causes genital warts. Because it also increases risk of cervical or penile cancer, it’s good to get an annual checkup.

Chlamydia

Chlamydia is one of the most common sexually transmitted diseases. This overview provides symptoms to watch for and treatment information.

Gonorrhea

If not treated gonorrhea can cause serious and permanent problems in both men and women. Here’s what you should know.

Syphilis

This serious infection can cause long-term health problems like arthritis, brain damage, and blindness -- unless it is treated. Know the symptoms.

Genital Herpes

Genital herpes is a common and highly contagious infection usually spread through sex. Usually this infection is caused by the herpes simplex virus-2 (HSV-2).

Hepatitis B

Hepatitis B is a serious disease caused by the hepatitis B virus (HBV). Infection with this virus can cause scarring of the liver, liver failure, liver cancer, and even death.

Painful Sex in Women

Intercourse pain, or dyspareunia, can cause problems in a couple's sexual relationship. In addition to the physically painful sex, there is also the possibility of negative emotional effects, so the problem should be addressed as soon as it becomes evident.

Vaginitis

Vaginitis is infection or inflammation of the vagina. It can cause itching and burning, a change in vaginal discharge, and sometimes pain during sex.

Vaginismus

When a woman has vaginismus, the muscle walls of her vagina contract or spasm in response to attempted insertion, for example, with a tampon or penis

Low Testosterone and Sex Drive

Testosterone isn't the only fuel for a man's sex drive and performance. But low testosterone can reduce your ability to have satisfying sex.

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Medical Investigations: Eight nutrients to protect the aging brain

Brain health is the second most important component in maintaining a healthy lifestyle according to a 2014 AARP study. As people age they can experience a range of cognitive issues from decreased critical thinking to dementia and Alzheimer's disease. In the March issue of Food Technology published by the Institute of Food Technologists (IFT), contributing editor Linda Milo Ohr writes about eight nutrients that may help keep your brain in good shape.

1. Cocoa Flavanols: Cocoa flavanols have been linked to improved circulation and heart health, and preliminary research shows a possible connection to memory improvement as well. A study showed cocoa flavanols may improve the function of a specific part of the brain called the dentate gyrus, which is associated with age-related memory (Brickman, 2014).

2. Omega-3 Fatty Acids: Omega-3 fatty acids have long been shown to contribute to good heart health are now playing a role in cognitive health as well. A study on mice found that omega-3 polyunsaturated fatty acid supplementation appeared to result in better object recognition memory, spatial and localizatory memory (memories that can be consciously recalled such as facts and knowledge), and adverse response retention (Cutuli, 2014). Foods rich in omega-3s include salmon, flaxseed oil, and chia seeds.

3. Phosphatidylserine and Phosphatidic Acid: Two pilot studies showed that a combination of phosphatidylserine and phosphatidic acid can help benefit memory, mood, and cognitive function in the elderly (Lonza, 2014).

4. Walnuts: A diet supplemented with walnuts may have a beneficial effect in reducing the risk, delaying the onset, or slowing the progression of Alzheimer's disease in mice (Muthaiyah, 2014).

5. Citicoline: Citicoline is a natural substance found in the body's cells and helps in the development of brain tissue, which helps regulate memory and cognitive function, enhances communication between neurons, and protects neural structures from free radical damage. Clinical trials have shown citicoline supplements may help maintain normal cognitive function with aging and protect the brain from free radical damage. (Kyowa Hakko USA).

6. Choline: Choline, which is associated with liver health and women's health, also helps with the communication systems for cells within the brain and the rest of the body. Choline may also support the brain during aging and help prevent changes in brain chemistry that result in cognitive decline and failure. A major source of choline in the diet are eggs.

7. Magnesium: Magnesium supplements are often recommended for those who experienced serious concussions. Magnesium-rich foods include avocado, soy beans, bananas and dark chocolate.

8. Blueberries: Blueberries are known to have antioxidant and anti-inflammatory activity because they boast a high concentration of anthocyanins, a flavonoid that enhances the health-promoting quality of foods. Moderate blueberry consumption could offer neurocognitive benefits such as increased neural signaling in the brain centers.

Medical Investigations: Pancreatic cancer breakthrough: Scientists turn cancer cells into normal cells

A new research study has shown that pancreatic cancer cells can be coaxed to revert back toward normal cells by introducing a protein called E47. E47 binds to specific DNA sequences and controls genes involved in growth and differentiation. The research provides hope for a new treatment approach for the more than 40,000 people who die from the disease each year in the United States.

"For the first time, we have shown that overexpression of a single gene can reduce the tumor-promoting potential of pancreatic adenocarcinoma cells and reprogram them toward their original cell type. Thus, pancreatic cancer cells retain a genetic memory which we hope to exploit," said Pamela Itkin-Ansari, Ph.D., adjunct professor in the Development, Aging, and Regeneration Program at Sanford-Burnham and lead author of the study published in the journal Pancreas.

E47 turns the clock back

The study, a collaborative effort between Sanford-Burnham, UC San Diego, where Itkin-Ansari holds a joint appointment, and Purdue University, generated human pancreatic ductal adenocarcinoma cell lines to make higher than normal levels of E47. The increased amount of E47 caused cells to stall in the G0/G1 growth phase, and differentiate back toward an acinar cell phenotype.

In vivo studies showed that when the reprogrammed cancer cells were introduced into mice, their ability to form tumors was greatly diminished compared to untreated adenocarcinoma cells.

"Presently, pancreatic adenocarcinoma is treated with cytotoxic agents, yet the average survival for patients post-diagnosis is merely six months, and the improvements in therapies are measured in days," said Andrew M. Lowy, M.D., professor of surgery at the UC San Diego Moores Cancer Center and co-chair of the National Cancer Institute's Pancreatic Cancer Task Force. "The finding that we can differentiate these cancer cells back to a non-threatening phenotype is encouraging. Indeed, there is a precedent for cell differentiation therapy in that the approach has been used to treat acute promyelocytic leukemia (APL) and some neuroblastomas successfully."

"Our next step is to test primary patient-derived tumor tissue to determine whether E47 can produce similar results, potentially providing a novel therapeutic approach to combat this highly lethal disease," said Itkin-Ansari. "Additionally, we are screening for molecules -- potential drugs -- that can induce overexpression of E47."

Pancreatic adenocarcinoma

Pancreatic adenocarcinoma is the most common form of pancreatic cancer. It's primarily caused by a mutation in the oncogene called Kras that causes the digestive enzyme-secreting cells (acinar cells) to differentiate into a destabilized duct-like cell type, which is cancerous. The disease is often called a "silent" cancer because it rarely shows early symptoms -- it tends to be diagnosed at advanced stages when it causes weight loss, abdominal pain, and jaundice.

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Medical Investigations: Impaired sleep linked to lower pain tolerance

People with insomnia and other sleep problems have increased sensitivity to pain, reports a study published in PAIN, the official publication of the International Association for the Study of Pain. The journal is published by Wolters Kluwer.

The effect on pain tolerance appears strongest in people who suffer from both insomnia and chronic pain, who may benefit from treatments targeting both conditions. The study was led by Børge Sivertsen, PhD, of the Norwegian Institute of Public Health, Bergen.

People with Insomnia Have Increased Pain Sensitivity

The study included more than 10,400 adults from a large, ongoing Norwegian health study. Each subject underwent a standard test of pain sensitivity--the cold pressor test--in which subjects are asked to keep their hand submerged in a cold water bath.

Subjects were asked about various types of sleep impairment, including insomnia, total sleep time, and sleep latency (time to falling asleep), and researchers assessed the relationships between measures of sleep impairment and pain sensitivity. The study also looked at other factors potentially affecting sleep impairment and pain perception, including chronic (persistent or recurring) pain and psychological distress (such as depression and anxiety).

Overall, 32 percent of participants were able to keep their hand in the cold water throughout the 106-second test. Participants with insomnia were more likely to take their hand out early: 42 percent did so, compared with 31 percent of those without insomnia.

Pain sensitivity increased with both the frequency and severity of insomnia. For example, compared with individuals who reported no insomnia, rates of reduced pain tolerance were 52 percent higher for subjects reporting insomnia more than once weekly versus 24 percent for those with insomnia once monthly.

Pain sensitivity was also linked to sleep latency, although not to total sleep time. The relationships were unchanged after adjustment for age and sex. The effect was smaller, but still significant, after further adjustment for psychological distress.

Synergistic Effect of Sleep Problems and Chronic Pain

There was also strong joint (synergistic) effect of insomnia and chronic pain on pain tolerance. Patients reporting high problems with both insomnia and chronic pain were more than twice as likely to have reduced tolerance to pain.

Many patients who experience sleep impairment and pain face high costs and personal difficulties. "While there is clearly a strong relationship between pain and sleep, such that insomnia increases both the likelihood and severity of clinical pain," Dr. Sivertsen and coauthors write, "it is not clear exactly why this is the case."

The new study is the first to link insomnia and impaired sleep to reduced pain tolerance in a large, general population sample. The results suggest that psychological factors may contribute to the relationship between sleep problems and pain, but they do not fully explain it. More research is needed to explore the role of neurotransmitters, such as dopamine, that may affect both pain and sleep.

Meanwhile, the study clearly shows the need for efforts to improve sleep among patients with chronic pain and vice versa. Cognitive-behavioral therapy approaches have proved effective for pain problems and insomnia individually. Dr. Sivertsen and colleagues call for studies evaluating earlier interventions targeting patients who are simultaneously affected by both problems.

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Medical Investigations: Potential new treatment for multiple sclerosis

Scientists from the Gladstone Institutes have discovered a way to prevent the development of multiple sclerosis (MS) in mice. Using a drug that blocks the production of a certain type of immune cell linked to inflammation and autoimmunity, the researchers successfully protected against the onset of MS in an animal model of the disease. The scientists say the next step is to test this strategy using other autoimmune disorders.

"We are very excited about these findings," says Eric Verdin, MD, a senior investigator at Gladstone and co-senior author on the study. "In light of the significant effect the treatment had on inflammation, the implications of these results will likely extend beyond multiple sclerosis to other types of autoimmune disorders. We are particularly interested in testing this in type I diabetes given the similar pathways involved, and we are already seeing very promising results in preliminary experiments."

In the immune system, two kinds of T cells strike a delicate balance--T helper cells (Th17) activate the immune system, protecting against infections and cancers, while regulatory T cells (Tregs) suppress the system, keeping it in check. A disparity between these cell types, where there are too many Th17 and not enough Tregs, can lead to a hyperactive immune system, resulting in inflammation, tissue damage, and autoimmune disease.

In the current study, published in the Journal of Experimental Medicine, the researchers discovered that an important regulatory protein, sirtuin 1 (SIRT1), is involved in the production of Th17 cells. By blocking this protein, the scientists can protect against the onset of autoimmunity. SIRT1 also has a negative impact on Treg maturation and maintenance, so inhibiting its expression simultaneously enhances the production of Tregs and suppresses the creation of Th17.

To test this effect on disease, the researchers used a mouse model of MS and treated the animals with a drug that inhibits SIRT1. Typically, MS-model mice experience severe motor problems, eventually leading to paralysis, but when they were given the drug the mice behaved perfectly normally. Moreover, the treated animals showed no signs of inflammation or cell damage in their spines, classic markers for MS.

In contrast with the current research, SIRT1 is typically thought of as having anti-inflammatory properties, and compounds that increase SIRT1--like resveratrol--have been proposed as a way to delay aging. However, first author Hyungwook Lim, PhD, a postdoctoral fellow at Gladstone, says the new research suggests that the protein's effects are more complicated.

"The conventional theory has been that you should activate SIRT1 to improve health and longevity, but we show that this can have negative consequences," says Dr. Lim. "Instead, we think the role of SIRT1 very much depends on the type of tissue being targeted. For instance, in immune cells, instead of being anti-inflammatory SIRT1 appears to have a pro-inflammatory role, which makes it a prime target to treat autoimmune disorders."

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Medical Investigations: Improving the effect of HIV drugs by the use of a vaccine

A vaccine containing a protein necessary for virus replication can boost an HIV-infected patient's immune system, according to clinical research published in the open access journal Retrovirology. This boost can result in increased effectiveness of antiretroviral drugs.

When people are first diagnosed with HIV they are put on antiretroviral drugs, also known as highly active antiretroviral therapy (HAART). These drugs can stop the virus reproducing almost completely. When taking HAART, however, it is known that the virus can still replicate at low levels and accumulate in a latent form in what are called "reservoirs." These reservoirs, located throughout the body including the brain, bone marrow and genital tract, cannot be acted upon by HAART and can cause complications and deaths due to non-AIDS related diseases.

A vaccine was developed that targets the viral protein "Tat," which is produced early on in HIV infection. Tat has a key role in viral replication and progression of the disease by weakening the immune system. By designing a vaccine that included a small amount of the Tat protein, researchers were able to produce an immune response to prevent disease progression.

Lead researcher, Barbara Ensoli, said: "We prove for the first time that antiretroviral therapy may be intensified by a vaccine. These results open new scenarios to investigate, namely whether this vaccine may help with virus control where patients have low adherence to antiretroviral therapy, simplify treatment, and reduce transmission of the disease."

Researchers from the Italian National AIDS Center at Istituto Superiore di Sanità (Rome, Italy) conducted a Phase II clinical trial that injected 168 HIV-infected patients with the vaccine that contained either 7.5 micrograms or 30 micrograms of the Tat protein. For both doses, the participants received the vaccine once a month over the course of either three or five months. None of the participants had anti-Tat antibodies at the start of the trial and it was anticipated that the vaccine would induce them. The patients also continued on HAART treatment.

Patients were followed for three years (144 weeks). It was found that the vaccine induced production of anti-Tat antibodies. A significant growth of CD4+ T cells was also seen, which is a sign of the immune system's strength. There was also an increase in the T, B and other immune cells. The biggest response was seen amongst those who received the vaccine with 30 micrograms of Tat over the course of three months. These effects were found to persist for all the three years.

Those who received the vaccine also had a significant reduction in HIV "proviral" DNA load, which acts as an indicator of the latent form of the virus in reservoirs. This reduction was compared to a group of 79 patients receiving only HAART enrolled in a separate observational study, which acted as reference group for biomarkers of the disease. This is different from an internal control group.

The researchers see the results as very promising for the treatment of HIV in the future. However, they await the results of future efficacy studies, and of a phase II double-blinded trial of the vaccine with a control that has taken place in South Africa, to confirm their findings.

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