What is Torsade de Pointes?
Torsades de Pointes is a kind of irregular heartbeat where the heart’s electrical activity shows a specific pattern on an EKG (an electrocardiogram, a test that checks your heart’s electrical activity). This pattern looks like the heartbeats are ‘twisting’ around an invisible line on the EKG. Torsades de Pointes is linked to a longer QTc period.
What’s a QTc period? It’s a measurement on an EKG that checks how long it takes your heart to recharge between beats. It changes slightly depending on your heart rate, which is why we ‘correct’ it to find the QTc. For men, a QTc is considered too long if it’s over 450 milliseconds, and for women, it’s too long if it’s over 460 milliseconds. If it’s over 500 milliseconds, it can increase the chances of Torsades de Pointes by two to three times.
The irregular heartbeat of Torsades de Pointes might stop on its own, or it might turn into a more dangerous irregular heartbeat called ventricular fibrillation.
What Causes Torsade de Pointes?
Torsades de pointes is a specific type of irregular heart rhythm that can be either inherited from birth (congenital) or develop later in life (acquired). Often, the acquired form is related to certain medications. These may include antiarrhythmics (used to treat heart rhythm problems), antipsychotics (used to manage mental health conditions), antiemetics (used to treat nausea and vomiting), antifungals (used to treat fungal infections), and antimicrobials (used to treat infections).
Certain substances that slow down the liver’s way of breaking down these medications can make it more likely for the heart rhythm to be affected, which can increase the chances of experiencing torsades de pointes.
In the case where this heart condition is inherited, there are two main types called Jervell and Lange-Nielsen syndrome and Romano-Ward syndrome. Interestingly, people with Jervell and Lange-Nielsen syndrome also usually have hearing loss.
Certain factors, including being older than 65, being female, having low levels of potassium, calcium, or magnesium in the blood, slow heart rate, heart disease, and taking water pills (diuretics) can also make it more likely for someone to experience this kind of irregular heart rhythm.
Lastly, Romano-Ward syndrome and Jervell and Lange Nielsen syndrome are two rare inherited conditions that can lead to long QT syndromes, a group of heart rhythm disorders that can cause fast, chaotic heartbeats.
Risk Factors and Frequency for Torsade de Pointes
Long QT syndrome, a heart condition that can cause fast, chaotic heartbeats, is often present from birth, but we’re not exactly sure how common it is. We think somewhere between 1 in 2,000 and 1 in 20,000 people has the genetic mutation that can cause it. It seems to show up more in men than in women. Another heart condition, drug-induced torsades de pointes, is hard to track because it often comes and goes quickly, and doctors can only diagnose it if they happen to be doing an ECG heart test during an episode. Some European research centers estimate that every year, 0.8 to 1.2 in a million people report having this condition. The likelihood of getting drug-induced torsades de pointes can depend on which medication a person is taking and the specific group of people being studied.
- The prevalence of the inherited condition, Long QT syndrome is uncertain, estimated to be between 1:2000 and 1:20,000.
- This syndrome appears to be more common in males than females.
- The occurrence of a certain heart rhythm disorder, known as drug-induced torsades de pointes, is also not well understood.
- This condition often comes and goes quickly, making diagnosis challenging unless an ECG is captured during an episode.
- Estimates from several European centers suggest 0.8 to 1.2 cases per million people each year of drug-induced torsades de pointes.
- The chance of experiencing drug-induced torsades de pointes can vary depending on the specific medication and the population being studied.
Signs and Symptoms of Torsade de Pointes
About half of the people with a condition called Torsades de Pointes may not show any symptoms. The ones who do, often experience fainting, heart palpitations, and dizziness. Unfortunately, in about 10% of cases, the first sign of this condition is a sudden cardiac death.
Another related condition is Jervell and Lange Nielsen syndrome. People with this syndrome often have a history of hearing loss.
It’s important to note that certain medications can lead to a similar condition called drug-induced long QT syndrome. This emphasizes the importance of providing a complete list of all the medications you’re taking to your healthcare provider.
Individuals with Torsades de Pointes may have a low blood pressure, fast heart rate, and can lose consciousness.
polymorphic nature of the tachycardia, the long QT interval and the initiation
of the tachycardia with a late coupled P.V.C.
Testing for Torsade de Pointes
An electrocardiogram, or EKG, is the main tool used to identify a heart rhythm problem known as Torsades de Pointes. Torsades de Pointes is often recognized by a distinctive pattern in the EKG readout. This pattern looks like a twisting of certain waveforms, called QRS complexes, around a baseline.
Usually, the development of Torsades de Pointes is instigated by an extra heartbeat happening during a specific phase of the heart rhythm, which is known as a PVC occurring on a preceding T wave. A series of heart rhythm sequences known as short-long-short R-R intervals often come before the onset of Torsades de Pointes.
A useful tool in ascertaining the risk of Torsades de Pointes related to certain medications that prolong the QTc (a specific segment of heart rhythm measurement) is the QT nomogram. This is a simple chart that plots a patient’s heart rhythm measurements. Dialing in on any values above the line on the chart can indicate a risk of developing Torsades de Pointes.
Treatment Options for Torsade de Pointes
Preventing the onset of a heart condition called Torsades de Pointes is typically the first strategy in its management. This can be achieved by addressing factors that can be changed, such as discontinuing any medications that extend the QT interval, a measure of some part of the heart’s electrical cycle, and balancing a patient’s electrolyte levels. Ensuring appropriate levels of potassium, magnesium, and calcium in the body can help prevent the onset of Torsades de Pointes. Some studies suggest that both oral and intravenous magnesium might prevent the condition if it’s caused by prolonged QT due to certain drugs; nonetheless, the overall benefit of this approach is not firmly established, and it seems that magnesium doesn’t affect the QT interval directly.
When a patient has Torsades de Pointes, the first thing doctors do is to check if the patient is stable. Although most cases of this condition resolve on their own, it can be dangerous in patients who then develop ventricular fibrillation, a serious heart rhythm disorder. In patients with low blood pressure or cardiac arrest due to Torsades de Pointes, a procedure to restore normal heart rhythm, called electrical cardioversion, should be performed.
Synchronized cardioversion is performed on an unstable patient who has a pulse, while defibrillation – an electric shock to the heart – is used if the patient doesn’t have a pulse. Intravenous magnesium is the primary medication given in this condition because it helps stabilize the heart, although exactly how this works is not fully understood. One common approach is to initially give a slow intravenous dose of 2 g of magnesium, followed by a continuous infusion to maintain magnesium levels above 2 mmol/L. The infusion can be stopped when the magnesium level is above 3mmol/L. Giving too much magnesium can lead to serious side effects such as confusion, respiratory depression, coma, and cardiac arrest. Alongside this, it’s also important to ensure that potassium levels are not low; they should be kept between 4.5 mmol/L and 5 mmol/L when treating Torsades de Pointes.
If a patient keeps having episodes of Torsades de Pointes despite magnesium treatment, another tactic is to increase their heart rate. This could be achieved with certain medications such as isoproterenol. This drug helps prevent Torsades de Pointes in patients with prolonged QT unresponsive to magnesium by increasing heart rate and shortening the QT interval, thus reducing the chance of a serious cardiac event. However, it’s worth noting that isoproterenol shouldn’t be given to patients with genetically prolonged QT as it can paradoxically extend the QT interval.
The final option for treating Torsades de Pointes is pacing the heart at high speed, known as overdrive pacing. Although there’s limited research on the success of this option, it’s reported in numerous case studies as a viable technique. Overdrive pacing can be employed when frequent bouts of Torsades de Pointes occur or when the condition doesn’t respond to magnesium. The pace should exceed the patient’s intrinsic heart rhythm to suppress the arrhythmia. Overdrive pacing is suggested both in cases of Torsades de Pointes induced by drugs and certain chemicals.
What else can Torsade de Pointes be?
The following are potential risks and complications associated with certain medical procedures or drug use:
- Fast or irregular heartbeats, also known as ventricular tachycardia or fibrillation
- Complications related to dialysis, a treatment for kidney failure
- Fainting, also referred to as syncope
- Overdose or harmful effects from certain medications such as antihistamines or antiarrhythmics
Possible Complications When Diagnosed with Torsade de Pointes
- Uncontrolled, rapid heartbeats
- Sudden heart stoppage leading to death
