FIELD OF THE INVENTION

The present application relates to methods and medical devices for providing an implantable cardioverter defibrillator system including a substernal lead.

BACKGROUND OF THE INVENTION

Malignant tachyarrhythmia, for example, ventricular fibrillation, is an uncoordinated contraction of the cardiac muscle of the ventricles in the heart, and is the most commonly identified arrhythmia in cardiac arrest patients. If this arrhythmia continues for more than a few seconds, it may result in cardiogenic shock and cessation of effective blood circulation. As a consequence, sudden cardiac death (SCD) may result in a matter of minutes.

In patients at high risk of ventricular fibrillation, the use of an implantable cardioverter defibrillator (ICD) system has been shown to be beneficial at preventing SCD. An ICD system includes an ICD, which is a battery powered electrical shock device, that may include an electrical housing electrode (sometimes referred to as a can electrode), that is coupled to one or more electrical lead wires placed within the heart. If an arrhythmia is sensed, the ICD may send a pulse via the electrical lead wires to shock the heart and restore its normal rhythm. Owing to the inherent surgical risks in attaching and replacing electrical leads directly within or on the heart, subcutaneous ICD systems have been devised to provide shocks to the heart without placing electrical lead wires within the heart or attaching electrical wires directly to the heart.

Subcutaneous ICD systems have been devised to deliver shocks to the heart by the use of a defibrillation lead placed subcutaneously on the torso. However, the subcutaneous ICD systems may require an output of around 80 Joules (J) of energy to provide effective defibrillation therapy. As a result, subcutaneous ICDs may require larger batteries and more storage capacitors than transvenous ICDs. As such, the subcutaneous ICDs are generally larger in size than transvenous ICDs. The large size of the subcutaneous ICD may compromise patient comfort, decrease system longevity and/or increase cost of the system. In addition, conventional subcutaneous ICD systems are incapable of delivering anti-tachycardia pacing (ATP) without extreme discomfort to the patient, which is a standard therapy in transvenous ICDs to terminate lethal tachyarrhythmias without providing a shock.

SUMMARY OF THE INVENTION

The present application advantageously provides implantable substernal ICD systems and methods for providing substernal electrical stimulation therapy to treat malignant tachyarrhythmia, e.g., ventricular tachycardia (VT) and ventricular fibrillation (VF). The substernal electrical stimulation therapy may take the form of shocks (e.g., either cardioversion or defibrillation shocks) or pacing pulses (e.g., ATP, post-shock pacing, or bradycardia pacing). Such an ICD system is thus capable of providing defibrillation or cardioversion shocks and/or pacing pulses without a lead that enters the vasculature, is implanted within the heart, or is attached to the heart.

In one embodiment, an ICD system comprises an ICD implanted subcutaneously in a patient and an implantable medical electrical lead. The implantable medical lead includes an elongated lead body having a proximal end and a distal portion, a connector at the proximal end of the lead body configured to couple to the ICD, and one or more electrodes along the distal portion of the elongated lead body. The distal portion of the elongated lead body of the lead is implanted substantially within an anterior mediastinum of the patient. The ICD is configured to deliver electrical stimulation to a heart of the patient using the one or more electrodes.

In another embodiment, a method comprises detecting a tachycardia with the implantable cardioverter-defibrillator (ICD) system having an ICD and a medical electrical lead. The medical electrical lead has a proximal end coupled to the ICD and a distal portion including one or more electrodes implanted substantially within an anterior mediastinum of a patient. The method further includes generating an electrical stimulation with the ICD in response to detecting the tachycardia and delivering the electrical stimulation to a heart of the patient via the one or more electrodes implanted substantially within the anterior mediastinum of the patient.

In another embodiment, an ICD system comprises an ICD implanted in a patient and an implantable medical electrical lead. The implantable medical lead includes an elongated lead body having a proximal end and a distal portion, a connector at the proximal end of the lead body configured to couple to the ICD, and a plurality of electrodes along the distal portion of the elongated lead body. The plurality of electrodes includes a defibrillation electrode and at least two sensing electrodes. The distal portion of the elongated lead body is implanted substantially within an anterior mediastinum of the patient. The ICD is configured to detect tachycardia using electrical signals sensed via the at least two sensing electrodes and to deliver one or more shocks to a heart of the patient via the defibrillation electrode in response to detecting tachycardia.

This summary is intended to provide an overview of the subject matter described in this disclosure. It is not intended to provide an exclusive or exhaustive explanation of the techniques as described in detail within the accompanying drawings and description below. Further details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the statements provided below.

