Heart failure devices

Medical Device Batteries describes wearable and implantable medical devices powered by batteries. Devices include those that are used for cardiac rhythm management (pacemakers, defibrillators, and heart failure devices), hearing loss, bone growth and fusirm, drug delivery for therapy or pain relief, nerve stimulation for pain management, urinary incompetence and nervous system disorders, vision, diagnostic measurements and monitoring, and mechanical heart pumps. 

Carbon monofluoride (CFx) is one such fluoride compound that today is used as a positive electrode material in Li batteries for a number of different applications. For example, they are used in certain types of heart failure devices - implantable cardiac resynchronization therapy pacemakers (CRT-P). CRT-P devices can pace the right atrium and right ventricle, but they are also capable of pacing the left ventricle. Pacing three chambers requires more power than a cell can deliver, so a different battery type is needed. Li/CFx cells were developed in response to the increased power required by CRT-P devices. Vagal nerve stimulator devices also use a Li/CFx cells. 

Implantable Cardioverter Defibrillators and Heart Failure Devices... 

Both leads can deliver pacing due to the "D" in the DVIR mode. Only the right ventricular lead can sense given the "V" in the second position. Thus, biventricular pacing is effectively accomplished with the short AV interval, the risk of double counting is eliminated as there is no sensing from the LV lead, and the cost of the standard dual chamber ICD is significantly lowered from that of a traditional biventricular heart failure device. 

Cardiac transplantation is one option for patients with severe heart failure. Candidates for cardiac transplantation generally present with New York Heart Association (NYHA) class III or IV symptoms and have an ejection fraction of less than 25%.1,3 The general indications for cardiac transplantation include rapidly declining cardiac function and a projected 1-year mortality rate of greater than 75%. Mechanical support with an implantable left ventricular assist device may be appropriate while patients await the availability of a viable organ.1,3 Some additional reasons for heart transplant include ... 

HCG human chorionic gonadotropin HCL hairy cell leukemia Hct hematocrit HCTZ hydrochlorothiazide HD hemodialysis HDAC histone deacetylase Hep hepatitis hepatotox hepatotoxicity HER2 type of cancer gene HF heart failure HFA designation for type of inhalation device Hgb hemoglobin HIT/HITTS heparin-mduced thrombocytopenia... 

The MADIT-CRT trial is enrolling patients who have an indication for an ICD, a low ejection fraction (LVEF < 40%), Class I or II heart failure, and a prolonged QRS duration to either an ICD alone or a CRT-D device. The primary endpoint of this study is all-cause mortality. 

Barbone A, Holmes JW, Heerdt PM, The AH, Naka Y, Joshi N, Daines M, Marks AR, Oz MC, Burkhoff D. Comparison of right and left ventricular responses to left ventricular assist device support in patients with severe heart failure a primary role of mechanical unloading underlying reverse remodeling. Circulation 2001 104 670-675... 

Radovancevic B, Vrtovec B, Frazier OH. Left ventricular assist devices an alternative to medical therapy for end-stage heart failure. Cwr Opin Cardiol 2003 18 210-214. 

In the near future it will be possible to monitor the status of heart failure using sensors incorporated in the newest generations of defibrillators. Major manufacturers of these devices have put in them the ability to monitor such parameters as heart rate variability, pressure in the right ventricle and force of contraction of the heart as well as many other parameters that are of as yet uncertain significance. As experience with using these data increases the ability to ascertain their utility in the management of patients will increase. 

The data recorded by these novel defibrillators can be downloaded in the office of the general and heart failure cardiologist with a simple device that will provide a printout of a heart failure profile, which can be used in the assessment of the patient at that clinic visit. This has been demonstrated by the... 

COMPASS investigators. In COMPASS, an implantable device that continuously monitors intra-cardiac pressures was shown to be safe and to improve care in patients with chronic heart failure [71]. Some simple measured parameters such as activity of the patient and heart rate and respiratory rate can be plotted over time to determine the patient s level of activity and provide insight into their functional status. 

As an integral member of THI s animal research team, Brano designed and preformed studies involving myocardial protection during cardiac operations, as well as temporary and permanent mechanical circulatory assist devices, heart valve prostheses, and synthetic vascular grafts. In addition he authored, and co- authored approximately 300 publications, and oversaw the writing of numerous heart failure and transplant protocols. 

Low doses (100-200 mg/d) of amiodarone are effective in maintaining normal sinus rhythm in patients with atrial fibrillation. The drug is effective in the prevention of recurrent ventricular tachycardia. It is not associated with an increase in mortality in patients with coronary artery disease or heart failure. In many centers, the implanted cardioverter-defibrillator (ICD) has succeeded drug therapy as the primary treatment modality for ventricular tachycardia, but amiodarone may be used for ventricular tachycardia as adjuvant therapy to decrease the frequency of uncomfortable cardioverter-defibrillator discharges. The drug increases the pacing and defibrillation threshold and these devices require retesting after a maintenance dose has been achieved. 

Brennan TD, Haas GJ. The role of prophylactic implantable cardioverter defibrillators in heart failure recent trials usher in a new era of device therapy. Curr Heart Fail Rep. 2005 2 40-45. 

Recent studies demonstrate that cardiac resynchronization therapy (CRT) offers a promising approach to selected patients with chronic heart failure. Delayed electrical activation of the left ventricle, characterized on the ECG by a QRS duration that exceeds 120 ms, occurs in approximately one-third of patients with moderate to severe systolic heart failure. Since the left and right ventricles normally activate simultaneously, this delay results in asynchronous contraction of the left and right ventricles, which contributes to the hemodynamic abnormalities of this disorder. Implantation of a speciahzed biventricular pacemaker to restore synchronous activation of the ventricles can improve ventricular contraction and hemodynamics. Recent trials show improvements in exercise capacity, NYHA classification, quality of life, hemodynamic function, and hospitalizations. A device that combined CRT with an implantable cardioverter-defibrillator (ICD) improved survival in addition to functional status. CRT is currently indicated only in NYHA class ni-IV patients receiving optimal medical therapy (ACE inhibitors, diuretics, -blockers, and digoxin) and... 

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