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Female hearts fibrillate differently

Gender-specific differences are currently not only a subject of debate for experts but have also raised broad media interest. However, there are very few specific investigations that are able to provide a clear answer, said Prof. Volker Kühlkamp, chief physician in the Department of Cardiology/Electrophysiology at the Lake Constance Heart Centre in Constance/Kreuzlingen and specialist in cardiac arrhythmia.

Prof. Volker Kühlkamp dealing with a critical case on the phone. (Photo: Keller-Ullrich)
Kühlkamp is involved in the development of new techniques for the treatment of cardiac arrhythmias, with a major focus on the catheter ablation of atrial fibrillation and the further development of implantable defibrillators.

Professor Kühlkamp has mixed feelings about the current interest in gender-specific differences. “The topic is a lot more complex than is assumed,” said the heart specialist explaining that women are on average ten years older than men at the time when similar changes of the coronary vessels are experienced.

Symptoms or differences in the general condition are therefore down to both gender and age. However, in the case of atrial fibrillation, which is the most common type of arrhythmia, there are clear differences between men and women.
“Female hearts fibrillate differently,” said Professor Kühlkamp. Women suffering from atrial fibrillation feel a lot worse than men and tolerate less strain. There are many reasons for this, which is why it is so is difficult to assess. The therapy of atrial fibrillation differs considerably between men and women; for example, fewer women are given the anti-coagulant Marcumar, although there is evidence that women in particular have a higher risk of embolisms.

Clinical trials also reveal gender-specific differences: the majority of study participants are men, because typical exclusion criteria for clinical studies are old age or the possibility of pregnancy. As mentioned above, cardiovascular diseases affect women later than men.

New medical technology for treating atrial fibrillation: catheter ablation

Prof. Volker Kühlkamp with his colleague Dr. Holger Stöckel in the laboratory (Photo: Keller-Ullrich)
The Lake Constance Heart Centre is involved in the development of new technologies for the treatment of cardiac arrhythmias, in which catheter ablation is one of the centre’s major priorities. Atrial fibrillation is quite common. Risk factors are high blood pressure, cardiac insufficiency or cardiac valve diseases. People suffering from atrial fibrillation have an irregular, often very rapid, pulse and suffer from strongly reduced capacities. The disease is mainly treated through medication.
If the medications given to stabilize the rhythm of the heart are not sufficiently effective, Professor Kühlkamp treats heartbeat irregularities with catheter ablation. Research has shown that the source of electrical irritability is often the opening of the pulmonary veins. The goal of catheter ablation is to isolate these electrical impulses to prevent them from spreading further. This is done with a catheter that targets the sites of the heart from where the arrhythmias originate. These areas will then be cauterized with high frequency alternating current. This leads to tiny point-shaped scars. A row of such scars forms what is referred to as ablation lines, which prevent the transmission of electrical impulses that cause the atria to fibrillate rather than contract in a regular pattern.

Although this method hasn’t yet become standard, Professor Kühlkamp is already testing the next generation of catheters, which are also equipped with an ultrasound head enabling the operating surgeon to visualise the correct areas for ablation. The new method works, but the physicians are now under pressure to provide evidence that the new method is more effective than the old one, explains Professor Kühlkamp.

Research priority: implantable defibrillators

Another one of Lake Constance Heart Centre’s research priorities is the further development of implantable defibrillators.

A defibrillator is used to treat cardiac arrhythmia. Systems that are currently available consist of an impulse generator that is implanted in the chest muscle under the skin. Electrodes from the generator are guided through veins into the heart where they are put in place. This system works relatively well; problems have been experienced with the probes, explains Professor Kühlkamp. About one third of the probes tend to become defective after ten years. The heart specialist is therefore testing a new generation of defibrillators that work without probes and can be easily replaced if necessary. The reliable and safe function of the new system depends on both specific algorithms for the recognition of the heart rhythm and new electrodes, which are implanted under the skin in the fatty tissue. The first phase of the study was completed successfully and the second phase has just got underway at the Lake Constance Heart Centre.

The new systems are not yet routinely implanted, but are being tested in operations where a traditional defibrillator is implanted. In addition, the researchers are testing how much energy is required to halt ventricular fibrillation, whether the system could be used as an emergency pacemaker and whether it is able to clearly recognize ventricular fibrillation.

Intelligent systems for the automated monitoring of at-risk patients

Nowadays, implantable defibrillators can also be used to monitor certain aspects of patients, for example their body’s fluid budget. This information can then be transmitted via mobile networks, enabling the treating physician to treat his or her patient with additional diuretic drugs should this be necessary.

Special pacemakers have to be continuously adapted to the current heart situation in patients suffering from severe cardiac insufficiency. As a result, the Constance experts are currently assessing possibilities of collaboration with the University of Tübingen. The plan is to run animal tests to find out whether the devices are able to automatically adapt their function to the extent of a patient’s cardiac insufficiency. The goal of these developments is to extend patient life span and quality.

Website address: https://www.gesundheitsindustrie-bw.de/en/article/news/female-hearts-fibrillate-differently