For a heart cast, where would the insertions normally be through?

Heart Cast Insertion Sites: Anatomical Considerations

For a heart cast, the insertions would normally be through the fourth or fifth intercostal space at the anterior axillary line for the main working port, with additional access points in the seventh intercostal space at the midaxillary line for supporting instrumentation. 1

Primary Insertion Sites

• The main working incision is typically placed in the fourth or fifth intercostal space at the anterior axillary line and extended approximately 4 cm laterally, allowing for insertion of atrial retractor blades and admitting 1-2 fingers for manipulation 1
• A secondary insertion site is created in the seventh intercostal space at the midaxillary line, which serves as an entry point for a left atrial sump 1
• A 5-mm trocar is typically placed through a separate stab wound one intercostal space above and more lateral than the working port to provide direct visualization with a thoracoscope 1

Anatomical Considerations for Optimal Access

• The main working incision usually falls at the level of the dome of the diaphragm, which may need to be retracted for proper access 1
• Internal finger palpation should be used to confirm proper placement and avoid damage to vital structures 1
• The fourth intercostal space should be palpated medially to confirm proper placement of the atrial retractor blade post just lateral to the right sternal border 1

Technical Approach for Cardiac Access

• After establishing the access ports, a soft tissue retractor is inserted to retract the intercostal muscles, allowing for smooth introduction of long-shafted instruments 1
• Carbon dioxide is typically infused in the field at a flow rate of 2-3 L/min through a soft drain to minimize the risk of air embolism 1
• The oblique sinus is opened widely, epicardial fat is cleared down to the atrial wall, and the Sondergaard groove is developed minimally to allow for accurate incision of the left atrium 1

Alternative Access Approaches

• For transapical access (when needed), the insertion is made through a left anterior thoracotomy after localizing the apex by fluoroscopy and echocardiography 1
• Transaortic access can be achieved through an upper partial sternotomy or a minithoracotomy at the second or third right intercostal space 1
• For coronary sinus access, a transatrial approach can be used with insertion through a small pursestring in the right atrium 2

Imaging Guidance for Accurate Placement

• Fluoroscopic guidance is essential for navigating catheters through the vascular system and into the heart chambers 3
• Echocardiographic imaging (transesophageal or transthoracic) helps confirm proper positioning and avoid complications 1
• For transapical access, the optimal position avoids the right ventricle and is angulated away from the interventricular septum 1

Potential Complications and Anatomical Pitfalls

• Care must be taken to avoid injury to the internal thoracic artery during insertion 1
• Atrial wall "tenting" should be avoided during atriotomy to prevent tissue damage 1
• Anatomical variants of the coronary sinus, including Thebesian valves (present in 54% of patients), may complicate access and should be identified 4, 5
• Awareness of the relationship between the access sites and surrounding cardiac structures is crucial to prevent inadvertent injury 6

By following these anatomical guidelines for insertion sites, operators can achieve optimal visualization and access for heart cast procedures while minimizing the risk of complications.