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Mechanics of the Chest Wall Muscles
Published in Alan D. Miller, Armand L. Bianchi, Beverly P. Bishop, Neural Control of the Respiratory Muscles, 2019
Although it has long been neglected, the triangularis sterni or transversus thoracis muscle has an important respiratory function in quadrupeds. In the dog and in the cat, it is invariably active and shortens during the expiratory phase of the breathing cycle.19 In so doing, it pulls the ribs caudally and deflates the rib cage below its resting position. When the muscle relaxes at end-expiration, there is therefore a passive cranial displacement of the ribs and an increase in rib cage volume that precedes the onset of the inspiratory muscle contraction. The triangularis sterni in these animals thus shares the work of breathing with the inspiratory muscles and helps the parasternal intercostals produce the rhythmic inspiratory expansion of the rib cage.
Ventricular Assistance as a Bridge to Cardiac Transplantation
Published in Wayne E. Richenbacher, Mechanical Circulatory Support, 2020
Protamine sulfate is administered and the effect of heparin sodium completely reversed. The activated clotting time (ACT) should return to baseline level. Blood product administration is directed by specific laboratory abnormalities of clotting parameters. Minimize blood product administration to reduce the antigen load in a patient who will ultimately require cardiac transplantation. The pericardium and left upper quadrant preperitoneal pocket, if present, are irrigated with vancomycin hydrochloride solution (1 gm in 1000 ml normal saline). The outlet graft from an implantable LVAD is located off the midline to lessen the chance of injuring this conduit at the time of sternal reentry and cardiac transplantation. The right rectus sheath is entered in the midline and the right rectus abdominis muscle elevated from the posterior rectus fascia (Fig. 6.5). The medial aspect of the right hemidiaphragm and adjacent transversus thoracis muscles are taken down from the right side of the sternum, xiphoid and costal arch. If necessary, the right pleural space is opened and the outlet graft positioned medial to the right lung. With the heart decompressed it is usually possible to close the pericardium even in the presence of VAD cannulae. Pay close attention to VAD filling and VAD flow as pericardial closure is completed. If there is a decline in VAD filling or flow the pericardium is left open. Pericardial closure is facilitated by using a pericardial membrane (Preclude pericardial membrane; W.L. Gore and Associates, Inc., Flagstaff, AZ).6 The membrane is sewn to the lateral edges of the pericardium at least to the level of the xiphoid process. This will further protect the right heart and outlet graft at the time of sternal reentry. The usual mediastinal tubes are employed; one anterior to the heart and one along the diaphragmatic surface. If an implantable blood pump is located in a preperitoneal position the pocket is drained with two 10 mm flat, fluted silicone drains (Blake drain; Johnson & fohnson Medical, Inc., Arlington, TX), one of which is located ventral and one dorsal to the blood pump. These drains are exteriorized through the dependent portion of the preperitoneal pocket. The sternum and midline incisions are closed as they would be for any routine open heart operation.
How to minimize peri-procedural complications during subcutaneous defibrillator implant?
Published in Expert Review of Cardiovascular Therapy, 2020
Muhammad R. Afzal, Toshimasa Okabe, Kevin Hsu, Schuyler Cook, Tanner Koppert, Raul Weiss
Adjunctive regional anesthesia using serratus anterior plain block and transversus thoracis muscle plane block have been shown to be safe and feasible during implantation of S-ICD [33,34]. Serratus plane block is performed under ultrasound guidance by placing the ultrasound at mid axillary line and moving medially to identify latissimus dorsi and serratus anterior muscle. The anesthetic medication is deposited in the latissimus dorsi and serratus anterior muscle plane. For the transversus thoracis muscle plane block, the ultrasound is placed on the left parasternal border at T3–T4 level and moved medially until the plane between the internal intercostal and transversus thoracis muscle is identified. The anesthetic medication is deposited between the internal intercostal and transversus thoracis muscle. Anesthesiology team typically performs these blocks. The studies have shown some subjective improvement in the requirement of pain medications in the postoperative period; although, there was no objective measurement for this. Further studies are needed to explore the role of adjunctive regional anesthesia. One limitation of this technique is the requirement of an anesthesiologist for pain block [35]. This may not be feasible from logistics standpoint and may incur additional financial burden.