Field of the Disclosure
This invention relates to a method for puncturing the pericardial membrane. More specifically, this invention relates to a method for puncturing the pericardial membrane by synchronizing needle advancement with cardiac muscle motion.
Description of the Related Art
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventor, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present invention.
As cardiac medical care advances, there is an increasing number of therapeutic procedures that require access into the pericardial space. Examples of such procedures are those needed for pacemakers, defibrillators, and ablation of certain arrhythmias. The pericardial space is a virtual space between the outside of the heart muscle and a thin layer of tissue that encases the heart muscle, called the parietal pericardium. The pericardial space contains a small amount of fluid, called the pericardial fluid.
The pericardial fluid is in constant contact with the heart muscle and the coronary arteries, and therefore, may be used to deliver drugs to the heart muscle and/or the coronary arteries. Since the pericardial fluid is of relatively low volume, such method of drug delivery requires a relatively lower dose of drug.
Additionally, the pericardial fluid may be used to introduce an agent into the pericardial space, while localizing the agent to the area around the heart muscle. Such agent is contained within the pericardial fluid, without contaminating other tissue or parts. Also, due to the low turn over rate of the pericardial fluid, such agent is sustained over a relatively long period of time.
Conventionally, and as shown in FIGS. 1A-1C, there are two commonly accepted locations on the chest that may be used for the insertion of the needle 107 to access the pericardial space 105: subxiphoid (FIGS. 1A and 1C) and apical (FIG. 1B). Although the apical location corresponds to a lower risk of damaging extracardiac structures, as not many exist in the needle's path, it is generally avoided due to the presence of a major coronary artery (the Left Anterior Decending coronary artery) in the area where the puncture occurs, and hence the associated risk of puncturing that artery and causing a heart attack. Access into the pericardial space 105 is attained with a blunt tip needle 107 adopted from the field of anesthesia, called the Tuohy needle. The Tuohy needle is an epidural introducer needle. To use the subxiphoid location to access the pericardial space 105 between the heart muscle 101 and the parietal pericardium 103, the needle 107 is carefully inserted between the Xiphoid process 109 and the diaphragm 111, and advanced toward the heart muscle 101 in order to penetrate the parietal pericardium 103 without damaging or penetrating the heart muscle 101.
Multiple advancements of the needle, with gradual increase in pressure applied to the parietal pericardium 103 may be required until it is punctured. In order to determine if/when the parietal pericardium 107 is punctured, test injections of a contrast agent may be done following each advancement. Once the parietal pericardium 107 is punctured, the contrast agent can be seen filling the pericardial space 105. At this point, no additional punctures are done.
With the exception of patients with a pericardial effusion (a large amount of fluid collection in the pericardial space due to bleeding or other disease process), the process of accessing the pericardial space 105 is a difficult one with a relatively high complication rate due to the small space between the parietal pericardium 103 and the heart muscle 101 (few millimeters at most) and the continuous motion of the heart before, during, and after puncturing the parietal pericardium 107.
In some cases, the needle tip may penetrate the heart muscle 101, creating a leak of blood from the inside of the heart into the pericardial space 105. Such leak can lead to tamponade and hypotension. In other cases, the needle tip may damage a coronary artery (arteries that supply the heart muscle with oxygen and nutrients), which can cause a heart attack. Such complications are life-threatening if not quickly and properly addressed.
Other possible risks include damage to extracardiac structures that are present in the needle's path. For example, the needle may puncture the stomach, colon, liver, or diaphragm. It may also lacerate an artery causing significant bleeding. Such complications are serious, and potentially life-threatening.
USPTO Backgrounds
USPTO Backgrounds