Minimally invasive surgeries (e.g., percutaneous surgeries) account for an increasing number of medical procedures. These surgeries may result in less patient trauma and may yield a significant cost savings as a result of shorter hospitalization times and reduced therapy requirements. Percutaneous procedures include endoscopic and catheter-based procedures such as angioplasty (e.g., balloon angioplasty), stent delivery, and tissue ablation. In many of these procedures, pain, and even tissue damage, can be reduced or eliminated by targeting delivery of anesthesia to the nerves or other tissues adjacent to the vessel in which the procedure is taking place.
Examples of two treatments that could benefit from the controlled application of anesthetic to specific tissues include angioplasty and tissue ablation. For example, carotid angioplasty and stenting can result in stimulation of the carotid sinus nerve, which can lead to bradycardia and hypotension, since acutely stretching or manipulating the carotid artery (which commonly occurs during angioplasty of this region) impinges on the sinus nerve. This can cause profound bradycardia or asystole, leading to severe drop in blood pressure. Patients with severe coronary artery disease or aortic stenosis may suffer cardiac arrest with hypotension. Stent placement can also cause prolonged distention of the carotid artery resulting in continuous stimulation of the carotid sinus nerve, and may require treatment with vasopressor medications requiring observation in an intensive care setting.
Similarly, the treatment of tissue within a vessel by ablation (e.g., using an ablation catheter), may deleteriously effect nearby tissue structures. Ablation of tissue from within the vessel lumen heats even non-target, e.g., adjacent tissue due thermal diffusion from the application of energy (e.g., electrical energy). This heat may cause pain or trauma. The use anesthesia, particularly tumescent anesthesia, is one method of reducing the negative effects of endoluminal ablation. Tumescent anesthesia typically involves providing local anesthesia to a surgical site using dilute local anesthetic solution to both numb and “inflate” the tissue around the target ablation zone. Historically, the delivery of anesthetic in tumescent anesthesia is accomplished by percutaneous introduction of the anesthetic with a hypodermic needle (e.g., see U.S. Pat. No. 6,258,084 to Goldman, et al., herein incorporated by reference in its entirety). This method is time consuming and requires repeated puncture of the skin if a significant surface area must be treated. Moreover, direct targeting of the structures to be rendered anesthetic may be diffuse and inaccurate, resulting in higher volumes and dose of anesthetic. Ideally, the tumescent anesthesia method would apply fluid (including fluid with anesthesia) to the perivesicular (or periluminal) region immediately surrounding the vessel in which the ablation catheter is positioned. In particular, the region around the blood vessel (e.g., between the endothelium and the subendothelial connective tissue) may be selectively injected with a solution of anesthetic to optimize the effectiveness of tumescent anesthesia.
Although many medical procedures (including angioplasty and tissue ablation as described) may benefit from the precisely controlled application of anesthetics, most practitioners continue to apply anesthesia with only limited specificity. Even when performing catheter-based minimally invasive surgery, may practitioners apply anesthesia either systemically (e.g., applying it to the entire patient) or by injecting the anesthesia into the appropriate body region using a needle. However, such percutaneous puncture results in difficult and imprecise deliver of anesthetic. This may also lead to injury of adjacent structures including the veins, arteries, nerves, musculature, etc. Furthermore, imprecise injection can also result in dislodging plaque, leading to thrombosis or other complications. These problems may be avoided by the precise delivery of anesthetic from within the lumen of a vessel.
Unfortunately, most devices for releasing drugs from within the lumen of a body vessel that are currently known, including most injection catheters and infusion catheters, suffer from various inadequacies that make them less than optimal for the precise delivery of anesthesia to different body regions. For example U.S. Pat. No. 6,210,392 to Vigil et al. describes an injection catheter for injecting fluid into a treatment area of a vessel wall. Similarly, U.S. Pat. No. 6,685,648 to Flaherty et al. describes a system and method for delivering drugs using a catheter having a deployable puncturing element. Other examples of injection catheters can be found in U.S. Pat. No. 6,458,098, U.S. Pat. No. 6,692,466, U.S. Pat. No. 5,354,279, U.S. Pat. No. 6,302,870, and U.S. Pat. No. 5,693,029. Each of the above-mentioned patents is herein incorporated by reference in its entirety.
Many of the injection catheters described in these patents do not allow precise control of the stability of the catheter and/or the injector, and therefore may have problems controlling the amount and location of material (particularly anesthetic) applied. Stability of the injection catheter is particularly important when it is desirable to apply a fluid (e.g., a fluid containing an anesthetic) to a precise location outside of the vessel lumen. Movement of the catheter caused by deploying the injection port may prevent proper delivery of the fluid, and may lead to damage of the vessel or extravesicular structures. This may be particularly true when the wall of the vessel is difficult to penetrate (e.g., because of plaque such as arterial plaques, etc.), or is irregularly shaped. Precise delivery of fluid allows for the selective use of normal tissue planes (e. as channels for distribution of the fluid, further enhancing the specificity and decreasing damage to the tissue.
Thus, there is a need for methods and devices for delivering fluids and/or anesthetics to precise locations adjacent to a body vessel from within the vessel. The devices, methods and systems described herein address this need, and the problems described above.
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