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Indications, Safety and Warnings

Reliance 4-Front™

CAUTION: Federal law (USA) restricts this device to sale by or on the order of a physician. Rx only. Prior to use, please see the complete “Directions for Use” for more information on Indications, Contraindications, Warnings, Precautions, Adverse Events, and Operator’s Instructions.

This Boston Scientific lead is indicated for use as follows:

  • Intended for pacing, rate-sensing, and delivery of cardioversion and defibrillation shocks when used with a compatible pulse generator

Use of this Boston Scientific lead is contraindicated for the following patients:

  • Patients who have a unipolar pacemaker
  • Patients with a hypersensitivity to a maximum single dose of 1.1 mg dexamethasone acetate
  • Patients with mechanical tricuspid heart valves



  • Labeling Knowledge: Read this manual thoroughly before implantation to avoid damage to the pulse generator and/or lead. Such damage can result in patient injury or death.
  • For single patient use only. Do not reuse, reprocess, or resterilize. Reuse, reprocessing, or resterilization may compromise the structural integrity of the device and/or lead to device failure which, in turn, may result in patient injury, illness, or death. Reuse, reprocessing, or resterilization may also create a risk of contamination of the device and/or cause patient infection or cross-infection, including, but not limited to, the transmission of infectious disease(s) from one patient to another. Contamination of the device may lead to injury, illness, or death of the patient.
  • Backup defibrillation protection. Always have external defibrillation equipment available during implant and electrophysiologic testing. If not terminated in a timely fashion, an induced ventricular tachyarrhythmia can result in the patient's death.
  • External-source rescue shocks. Do not use any component of the lead system to assist in delivery of external-source rescue shocks or extensive tissue damage could occur.
  • Resuscitation availability. Ensure that an external defibrillator and medical personnel skilled in CPR are present during post-implant device testing should the patient require external rescue.
  • Lead fracture. Lead fracture, dislodgment, abrasion, or an incomplete connection can cause a periodic or continual loss of pacing or sensing or both.  This could possibly result in arrhythmia nondetection, oversensing of rate, inappropriate delivery of a pulse generator shock, or inadequate delivery of converting energy.


  • Excessive flexing. Although pliable, the lead is not designed to tolerate excessive flexing, bending, or tension. This could cause structural weakness, conductor discontinuity, and/or lead dislodgment.
  • Do not kink leads. Do not kink, twist, or braid the lead with other leads as doing so could cause lead insulation abrasion damage or conductor damage.
  • Handling the lead without Connector Tool. Use caution handling the lead terminal when the Connector Tool is not present on the lead. Do not directly contact the lead terminal with any surgical instruments or electrical connections such as PSA (alligator) clips, ECG connections, forceps, hemostats, and clamps. This could damage the lead terminal, possibly compromising the sealing integrity and result in loss of therapy or inappropriate therapy.
  • Handling the terminal while tunneling. Do not contact any other portion of the lead terminal, other than the terminal pin, even when the lead cap is in place. 

Implant Related

  • Do not implant in MRI site Zone III. Implant of the system cannot be performed in an MRI site Zone III (and higher) as defined by the American College of Radiology Guidance Document on MR Safe Practices. Some of the accessories packaged with pulse generators and leads, including the torque wrench and stylet wires, are not MR Conditional and should not be brought into the MRI scanner room, the control room, or the MRI site Zone III or IV areas.
  • Separate defibrillation electrode. In order to deliver defibrillation therapy, the single-coil models must be implanted with an additional defibrillation electrode. It is recommended to use the pectorally implanted defibrillator pulse generator that uses the metallic housing as a defibrillation electrode.
  • Only use Connector Tool for electrical connections. For DF4-LLHH or DF4-LLHO leads, only use the Connector Tool for electrical connections to pacing system analyzers or similar monitors. Do not attach alligator clips directly to the lead terminal or damage could occur.
  • Obtain appropriate electrode position. Take care to obtain appropriate electrode position. Failure to do so may result in higher defibrillation thresholds or may render the lead unable to defibrillate a patient whose tachyarrhythmia(s) might otherwise be convertible by a pulse generator system.
  • Proper connections. When connecting the lead to the pulse generator, it is very important that proper connections are made. The terminal pin must be inserted beyond the setscrew block to enable a proper connection. Visualization of the terminal pin insertion indicator beyond the setscrew block may be used to confirm that the terminal pin is fully inserted into the pulse generator port. Evaluation of the electrical performance of the lead after connection to the pulse generator is the final confirmation of full insertion. An improper connection could result in loss of therapy or inappropriate therapy.

Post Implant

  • Magnetic Resonance Imaging (MRI) exposure. Unless all of the MRI Conditions of Use (as described in the MRI Technical Guide) are met, MRI scanning of the patient does not meet MR Conditional requirements for the implanted system, and significant harm to or death of the patient and/or damage to the implanted system may result. Refer to the MRI Technical Guide for potential adverse events applicable when Conditions of Use are met or not met, as well as for a complete list of MRI-related Warnings and Precautions.
  • Diathermy. Do not subject a patient with an implanted pulse generator and/or lead to diathermy since diathermy may cause fibrillation, burning of the myocardium, and irreversible damage to the pulse generator because of induced currents.


  • Electrode placement above midseptum. The safety and efficacy of the tip electrode placement in the right ventricle above midseptum has not been clinically established.
  • Use fluoroscopy to verify lead position. Use fluoroscopy to verify that the lead tip is directed toward the apex when implanted.


For specific information on precautions, refer to the following sections of the product labeling: clinical considerations, sterilization and storage, handling, implantation, hospital and medical environments, follow up testing, and explant and disposal.


Based on the literature and on pulse generator and/or lead implant experience, the following alphabetical list includes the possible adverse events associated with implantation of products described in this literature:
Air embolism; Allergic reaction; Arterial damage with subsequent stenosis; Bleeding; Bradycardia; Breakage/failure of the implant instruments; Cardiac perforation; Cardiac tamponade; Chronic nerve damage; Component failure; Conductor coil fracture; Death; Electrolyte imbalance/dehydration; Elevated thresholds; Erosion; Excessive fibrotic tissue growth; Extracardiac stimulation (muscle/nerve stimulation); Fluid accumulation; Foreign body rejection phenomena; Formation of hematomas or seromas; Heart block; Hemorrhage; Hemothorax; Inability to defibrillate or pace; Inappropriate therapy (e.g., shocks and antitachycardia pacing [ATP] where applicable, pacing); Incisional pain; Incomplete lead connection with pulse generator; Infection including endocarditis; Lead dislodgment; Lead fracture; Lead insulation breakage or abrasion; Lead tip deformation and/or breakage; Local tissue reaction; Low amplitude VF signals; Malignancy or skin burn due to fluoroscopic radiation; Myocardial trauma (e.g., irritability, injury, tissue damage); Myopotential sensing; Oversensing/undersensing; Pericardial rub, effusion; Pneumothorax; Post-shock rhythm disturbances; Pulse generator and/or lead migration; Shunting current during defibrillation with internal or external paddles; Syncope; Tachyarrhythmias, which include acceleration of arrhythmias and early, recurrent atrial fibrillation; Thrombosis/thromboemboli; Valve damage; Vasovagal response; Venous occlusion; Venous trauma (e.g., perforation, dissection, erosion)
Transient procedural adverse events are expected in some patients. These include, but are not limited to, discomfort, pain, and other systemic symptoms that might be related to medications or other interventions performed during implant.
For a list of potential adverse events associated with MRI scanning, refer to the ImageReady MR Conditional Defibrillation System MRI Technical Guide.

92436280 (Rev. B)