Blood pressure monitoring may be used to assist a medical practitioner in diagnosing cardiovascular and other conditions of a patient. In many instances, blood pressure is monitored indirectly since this technique is relatively non-invasive and is useful for obtaining an approximate blood pressure measurement. Typically, a sleeve is placed around a patient's limb, and the patient's blood pressure is measured on a pressure gauge coupled to the sleeve. In some circumstances, however, a more accurate blood pressure measurement may be needed. In such case, direct blood pressure monitoring, utilizing a device that is surgically implanted into a patient's bloodstream, may be employed.
Some direct pressure monitoring device configurations include a capsule having a pressure transducer disposed therein. The capsule includes an opening that allows fluid to contact the pressure transducer directly. When the device is appropriately deployed within the patient (e.g. within the patient's blood vessel proximate the patient's heart or within a chamber of the patient's heart), blood that is pumped by the heart exerts pressure against the pressure transducer. The pressure transducer, in turn, senses the exerted pressure and communicates a signal representative of the sensed pressure to a pressure measurement gauge or other appropriate pressure measuring device.
Although the above-mentioned pressure monitoring devices are useful in many circumstances, they may have certain drawbacks. For example, because the pressure transducer directly contacts the patient's blood, it may be more susceptible to corrosion. Thus, in cases in which the pressure transducer includes an integrated circuit chip, the device may degrade over time. Furthermore, blood may coagulate around the capsule opening, which may, in turn, affect pressure transducer operation. As a result, these types of pressure monitoring devices may not be suitable for long-term pressure monitoring.
In recent years, pressure monitoring devices have been developed to overcome the aforementioned drawbacks by encasing a pressure transducer within a fluid-filled, smooth-surfaced capsule and rigidly attaching the pressure transducer to the capsule. The capsule includes a flexible diaphragm disposed over an opening. When pressure is exerted on the diaphragm, the pressure is transferred to the pressure transducer via the fluid. The pressure transducer communicates with an implantable medical device or other appropriate medical device via a pressure monitoring lead. This device configuration decreases the corrosion experienced by the pressure transducer, reduces blood coagulation on the capsule, and may be implanted into a patient for relatively long-periods of time. However, when the pressure monitoring device is disposed within a patient's heart chamber, heart contractions may cause force to be applied to the lead, and therefore directly to the rigidly attached pressure transducer. This undesirable strain may decrease the structural integrity of the pressure monitoring device over time.
Accordingly, it is desirable to have a relatively simple and inexpensive pressure monitoring device that has a corrosion-resistant configuration and is capable of being implanted into a patient for long periods of time. In addition, it is desirable to have a pressure monitoring device that is configured to reduce strain due to lead movement. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.