Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical therapeutic systems
Reexamination Certificate
2001-03-16
2003-11-18
Vo, Hieu T. (Department: 3747)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical therapeutic systems
C600S486000, C607S006000, C607S009000, C607S112000
Reexamination Certificate
active
06650939
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to implantable hemodynamic monitors (IHMs). Specifically, the invention relates to a device that interfaces with various hospital monitoring systems and various equipments fabricated by different manufacturers to transfer data from the IHMs to hospital monitoring systems. More specifically, the invention pertains to a data management interface system that is compatible with various models of monitoring equipment built by different manufacturers. Further, the invention relates to a data management system that connects IHMs and a remote monitoring system to transfer the patient's medical data and information to an expert data station center where expert systems and personnel are stationed to monitor patients located in various hospital rooms and/or wards.
BACKGROUND OF THE INVENTION
Health care professionals are fully aware of the need to monitor, on a frequent or continuous basis, the vital signs associated with hospitalized patients, particularly those who are seriously and chronically ill. Virtually every hospitalized patient requires periodic measurement and logging of blood pressure, temperature, pulse rate, etc. This type of monitoring has typically been performed by having a health care worker periodically visit the bedside of the patient and measuring and/or observing the patient's vital signs using dedicated equipment that is either hooked up to the patient or brought into the patient's room. Current monitoring procedures are not ideally cost effective because of being highly labor intensive. Moreover, if an invasive procedure is used, the need to continuously monitor the patient becomes critical because of the associated risk.
To alleviate such concerns, hospitals have adopted new and improved patient monitoring methods and processes. The two most frequently used are 1) intensive care wards and 2) “stepped down” care or “monitored bed” wards. In an intensive care ward, physicians and staff check the patient frequently and directly observe pressure signals on the bedside monitor. This bedside monitor is usually connected, via hardwire, analog or digital, to a central nurses'station where the pressure can be continuously watched or observed. These readings can also be documented by placing them in digital storage such as a disk, for example, or printed on paper for inclusion in the patient's file. A “stepped down” ward is a less intensive setting in which the patient can be monitored as described above. In either case, the pressure monitors may be hardwired or connected via RF to central monitoring stations.
A great many implantable medical devices (IMDs) are currently used for cardiac monitoring and/or therapy. Generally, these devices include sensors located in a blood vessel or heart chamber and coupled to an implantable monitor or therapy delivery device. For example, IMDs include implantable heart monitors, therapy delivery devices such as pacemakers, cardioverter/defibrillators, cardiomyostimulators, ischemia treatment devices, and drug delivery devices. Typically, these cardiac systems include electrodes for sensing and sense amplifiers for recording and/or deriving sensed event signals from the intracardiac electrogram (EGM). In current cardiac IMDs that provide a therapy, the sensed event signals are used to control the delivery of the therapy in accordance with an operating algorithm. Selected EGM signal segments and sensed event histogram data or the like are stored in internal RAM for data telemetry via an external programmer at a later time.
Efforts have also been underway for many years to develop implantable physiologic signal transducers and sensors for temporary or chronic use in a body organ or vessel usable with such IHMs for monitoring a physiologic condition other than, or in addition to the disease state that is to be controlled by a therapy delivered by the IMD. A comprehensive listing of implantable therapy delivery devices are disclosed in conjunction with implantable sensors for sensing a wide variety of cardiac physiologic signals in U.S. Pat. No. 5,330,505, incorporated herein in its entirety by reference.
Typically, an IHM measures right ventricular (RV) blood pressure that stems from changes in cardiac output that may be caused by a cardiac failure, ventricular tachycardia, flutter, or fibrillation. These variations may reflect a change in the body's need for oxygenated blood. An IHM may also measure temperature, a compensatory variable. Measuring temperature is used in these situations to correct for potential erroneous judgment stemming from changes in RV pressure resulting from body temperature changes. Temperature measurements have been used informally to identify disease processes not attributable to heart failure, such as the flu, which might be confused with changes in pressure that otherwise might be attributable to heart failure.
For example, as disclosed in U.S. Pat. No. 6,024,704 issued to Meador et al, monitoring of a substantial drop in blood pressure in a heart chamber, particularly the right ventricle, alone or in conjunction with an accelerated or chaotic EGM, is considered as an indicator of fibrillation or tachycardia sufficient to trigger automatic delivery of defibrillation or cardioversion shock. More recently, it has been proposed to monitor the changes in the blood pressure type (dP/dt) by comparing the absolute blood pressure rise and fall rates (dP/dt) that accompany the normal heart contraction and relaxation to those that occur during high rate tachycardia, flutter, or fibrillation.
A number of cardiac pacing systems and algorithms for processing the monitored mean blood pressure or monitored dP/dt have been proposed and, in some instances employed clinically, for treating bradycardia. Such systems and algorithms are designed to sense and respond to changes in mean blood pressure or dP/dt, to change the cardiac pacing rate (rate responsive pacing) between an upper and a lower pacing rate limit in order to control cardiac output.
Such IHMs, blood pressure, and temperature sensors that derive absolute blood pressure signals and temperature signals are disclosed in commonly assigned U.S. Pat. Nos. 5,368,040, 5,535,752 and 5,564,434, and in U.S. Pat. No. 4,791,931 all incorporated by reference herein. The MEDTRONIC® Chronicle® Implantable Hemodynamic Monitor (IHM), disclosed in U.S. Pat. Nos. 6,024,704 and 6,152,885 both incorporated herein by reference in their totality, employs the leads and circuitry disclosed in the above-incorporated, commonly assigned, '752 and '434 patents to record absolute blood pressure values for certain intervals. The recorded data is transmitted to a programmer preferably under the control of a physician in an uplink telemetry transmission from the IHM. As is well known in the art, a telemetry session is initiated by a downlink telemetry transmission from the programmer's radio frequency (RF) head and receipt of an interrogation command by the IHM.
Thus, in accordance with the disclosures in the '704 and '885 patents, an IHM for deriving an absolute pressure signal value is coupled and compared with a barometric reference signal using implantable physiologic sensor(s) to determine a resultant nonabsolute cardiac pressure signal values for storage and transmission. Further, the patents ('704 and '885) disclose a system of calibration of the reference pressure and/or temperature sensor in relation to an external, calibrated, barometric pressure and/or body temperature sensor. This system may be implemented to interlace digital signal values (related to pulmonary artery diastolic pressures) with the primary cardiac pressure signal values derived from the right ventricle, as disclosed in U.S. Pat. No. 6,155,267 incorporated herein by reference.
In accordance with the present invention, an IHM may be implanted in a rather broadly defined group of patients. The requirements for implant include symptomatic heart failure of at least 3 months duration. These are the sickest patient
Beck Robert C.
Bennett Tom D.
Deno D. Curtis
Roberts Jonathan P.
Shaw Richard J.
Chapik Daniel G.
Hoang Johnny H.
Medtronic Inc.
Vo Hieu T.
Wolde-Michael Girma
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