The purpose of this clinical study is to assess the safety and performance of the Vision-MR Ablation Catheter, the primary safety endpoint will measure the rate of serious adverse events related to the device or procedure; the primary performance endpoint will measure the acute success rate defined as the demonstration of bidirectional cavo-tricuspid isthmus block after radiofrequency application in the cavo-tricuspid isthmus; the secondary performance endpoint will measure the chronic success rate defined as the freedom of recurrence of type 1 atrial flutter at three months post-ablation procedure. The study will be a single center study conducted at the Leipzig University Hospital Heart Center in Germany. The study population will consist of adult patients requiring ablation for type I atrial flutter.

This is the follow-up study to NCT02699034.

The study will be a single center study conducted at the Leipzig University Hospital Heart Center in Germany. 35 subjects subjects meeting inclusion/exclusion criteria will participate in the study. This study requires the use of investigational products from two independent manufacturers: Imricor and Philips. Imricor has developed the ablation catheter with related accessory cables and electrophysiology (EP) recorder/stimulator system. Philips has developed an image guidance and mapping system that is compatible with the Imricor products.

The Vision-MR Ablation Catheter will be used in conjunction with the following investigational products: Vision-MR Ablation Cable Set, Vision-MR Diagnostic Cable, the interventional MRI Suite (iSuite) image guidance and mapping system, and a dStream Interface (dSIF-FE). With the exception of iSuite and dSIF-FE, which are manufactured by Philips, Imricor will provide all investigational devices used in the study.

Each procedure will require two single-use Vision-MR Ablation Catheters and one each of the two single-use accessory catheter cables.

Ablation for the treatment of arrhythmia is an inherently complex procedure. Use of the investigational products listed above under MR guidance is an emerging approach to performing the interventional electrophysiology procedure.

The study population will consist of adult patients requiring ablation for type I atrial flutter.

Study subjects will require a follow-up visit or telephone call at seven days post procedure. Accordingly, the expected total study duration is approximately 9 months with study start planned for February 2017.

This is the follow-up study to NCT02699034 which was terminated early based on a recommendation by the oversight authority. The study device (Vision-MR ablation catheter) has been improved and the EP recorder/stimulator is now CE-marked.

Inclusion Criteria:

• First time indication for ablation for type I atrial flutter.
• Patients willing and able (mentally and physically capable per physician's discretion) to understand the investigational nature, potential risks and benefits of the study and able to provide written informed consent to participate in the study and agree to comply with follow-up visits and evaluation
• Patients able to receive anticoagulation therapy to achieve adequate anticoagulation

Exclusion Criteria:

• Contraindication for MRI diagnostic exam
• A cardiac ablation or cardiac surgery within 180 days prior to enrollment
• Documented intracardiac thrombus, tumor, bleeding, clotting or other abnormality that precludes catheter introduction and placement
• Myocardial infarction within 60 days prior to enrollment
• Current unstable angina
• History of cerebrovascular event (within 180 days prior to enrollment)
• Patients with an ejection fraction less than or equal to 35% within 90 day prior to enrollment
• Permanent leads in or through the right atrium
• Clinically significant structural heart disease (including tricuspid valve regurgitation, tricuspid valve stenosis or other congenital heart disease) that would preclude catheter introduction and placement, as determined by the Investigator
• Uncompensated congestive heart failure (NYHA Class III or IV)
• Arrhythmia is secondary to electrolyte imbalance, thyroid disease, or other reversible or non-cardiovascular cause
• Known sensitivity to heparin or warfarin
• Active or systemic infection
• Any other significant uncontrolled or unstable medical condition (including but not limited to hypertension and diabetes)
• contraindication for conventional ablation procedure know allergy against radiocontrast agents renal insufficiency with glomerular filtration rate < 30ml/min/1,73m2
• Women who are pregnant or plan to become pregnant within the course of their participation in the investigation or who are breastfeeding
• Life expectancy of less than 12 months
• Patients with prosthetic valves
• Contraindicated for transfemoral venous access
• Older than 75 years
• Current enrollment in any other clinical investigation

This an Open Label study.