Ventricles, coronary vessels and access to conduits for grafting

The right ventricle is the most anterior part of the heart; injuries at sternotomy are known to happen, especially with right ventricular hypertrophy in the paediatric age group and at reoperations where this chamber may be stuck to the posterior aspect of the sternum. Preoperative imaging with lateral chest X-ray and CT allows detailed assessment of cardiac anatomy posterior to the sternum and changes in operative strategy to mitigate this risk by either adopting a thoracotomy approach or establishing cardiopulmonary bypass using peripheral cannulation, most often femoral vessels, prior to sternotomy.

At redo operations, sternotomy is performed using an oscillating saw, lifting up the sternum off the underlying structures (anterior surface of right ventricle, aorta or bypass grafts) either by inserting retractors with small blades under the suprasternal notch and xiphoid process or by taking deep sutures going through the muscles and periosteum on either side of the midline. Following sternotomy, sternal retraction should be minimal to allow division of adhesions on either side before full retraction. Forceful retraction of the sternum right at the beginning may induce a right ventricular tear because of the pull of adhesions between the sternum and the anterior surface. If a right ventricular tear happens despite all precautions, either caused by the saw or during retraction, gentle digital pressure using the pulp of a finger is used to control the bleeding. This may not be possible if bleeding is caused by a sternal saw right at the beginning: in such situations, some control can be achieved by pressing the two halves of the sternum together using one hand in each axilla pressing the chest. While temporary control is obtained, expeditious cardiopulmonary bypass is established peripherally using femoral vessels by a second surgeon. Similar injury from a saw is possible at first sternotomy in patients with right ventricular hypertrophy. An assistant's finger placed longitudinally on the tear controls the bleeding long enough for the surgeon to repair the tear using continuous over-and-over polypropylene suture.

In desperate situations, use of a Foley catheter or even an endotracheal tube inserted though the tear may rescue the surgeon. Once inside the lumen, the balloon is inflated and gentle traction of the balloon against the wall of the chamber can seal the leak while cardiopulmonary bypass is established. An endotracheal tube can be connected to the venous drainage to the bypass machine, understanding that alternative drainage will be required once the situation has been defused.

Tetralogy of Fallot (TOF) is a very common congenital cardiac defect and corrective surgery is performed in early life. Right ventricular hypertrophy is quite prominent with very pronounced trabeculae in the cavity. The supraventricular crest forms the posterior rim of the perimembranous ventricular septal defect. There is a risk of injury to the right coronary artery if deep sutures are taken to repair the defect in this part, with the needle going into the right atrioventricular groove.

Lateral chest X-ray and chest CT scan are extremely useful to assess anatomy prior to redo operations.

A strategy to lift the sternum during sternotomy is useful to minimize the risk of injury to the right ventricle in these situations.

Gradual step-by-step sternal retraction is recommended to avoid right ventricular tears due to stretch from adhesions in a redo operation.

The right ventricle is the most anterior structure of the heart and is therefore prone to injury when hypertrophied and in redo sternotomy settings.

Deep sutures through the supraventricular crest at perimembranous ventricular septal defect closure may cause injury to the right coronary artery.

Left ventricular aneurysms are most often anterolateral (85%). They follow myocardial infarction in left anterior descending artery territory, as a part of either multivessel coronary disease or single-vessel disease ( Fig. 53.2 ).

Posterior aneurysms make up 5–10% ( Fig. 53.3 ). The rest are either inferior or lateral aneurysms, of which more than 50% are pseudoaneurysms, caused by leak of blood contained within the pericardium. Anterolateral aneurysms are located next to the apex of the ventricle. During repair, they are opened longitudinally along the long axis of the heart, allowing linear closure. Aneurysms should be opened carefully to avoid injury to the papillary muscles, especially posterior or inferior aneurysms. True aneurysms in these areas most often require a circular patch to close the mouth and avoid distortion of papillary muscles, which may cause mitral regurgitation.

In patients with ventricular septal defects ( Fig. 53.4 ) following myocardial infarction, the left ventricle is incised in the infarcted region. It is most commonly associated with anterolateral infarct and approached via a longitudinal incision just lateral to the interventricular groove. Ventricular septal defect in the posterior septum is usually approached by lifting the apex upwards to expose the posterior surface of the heart and incising the left ventricle in the infarcted area parallel to the posterior interventricular groove. The infarction can be associated with mitral regurgitation from involvement of posterior papillary muscle, requiring concomitant mitral valve surgery. Right atrial and right ventricular surgical approaches, as well as percutaneous device closure, have been reported with successful outcomes; however, they are not routinely applied.

Left ventricular rupture due to myocardial infarction is most often fatal and a postmortem finding. Rarely, it may be manifest as a slow and contained leak forming a pseudoaneurysm, which has to be treated on an urgent or emergent basis due to the high risk of rupture. In these situations, the pseudoaneurysms almost always originate from the posterolateral wall ( Fig. 53.5 ). However, they may track around the lateral aspect and reach under the sternum anteriorly, making sternotomy or sternal retraction dangerous. Establishing peripheral cardiopulmonary bypass using femoral vessels prior to sternotomy may be the only possible approach in such anatomy.

Left ventricular free wall rupture as a complication of surgery in case of mitral operations occurs most often in the subanular region. Lifting the heart to localize this area with a rigid prosthesis in situ in the mitral anulus is not recommended for fear of extending this tear. The only way to approach this would be to stop the heart again with cardioplegia, remove the prosthesis and then repair the rupture.

In both of these situations, localizing and defining the actual tear may be impossible due to the haematoma in the left ventricular myocardium, which makes it oedematous and extremely friable. Various glues have become very useful in these cases, to cover the area widely and then cover this with a wider patch sutured on to the normal myocardium away from the area of rupture. In patients with a pseudoaneurysm with a small mouth, where the patient is haemodynamically stable, the possibility of percutaneous device closure should be explored.

Do not attempt direct closure of post-infarct or intraoperative left ventricular tears; use sealants, haemostatic adjuncts with a wide patch sutured to normal myocardium.

Insert a left ventricular vent at the apex between the left anterior descending and diagonal arteries.

Close the vent site at the end before coming off cardiopulmonary bypass between two adequately sized Teflon pledgets using 3-0 or 4-0 polypropylene sutures.

In redo operations, an apical vent may be inserted prior to sternotomy via a small left anterior thoracotomy.

Assess pseudoaneurysms with a CT scan prior to repair; establish peripheral cardiopulmonary bypass prior to sternotomy if this is tracking under the sternum.

Avoid injury to papillary muscles at vent insertion, repair of aneurysms and ventricular septal defects by proper siting of incisions.

Use information obtained on preoperative imaging, especially intraoperative transoesophageal echocardiogram.

Papillary muscles may be injured if a left ventricular vent inserted via the apex is not sited carefully.

Opening posterior or lateral aneurysms may damage the papillary muscles, especially posteromedial ones.

Sternotomy in pseudoaneurysm repair may be catastrophic if this has tracked around the heart to reach under the sternum.

Posteromedial papillary muscle is prone to injury during posterior post-infarct VSD repair.

A left ventricular apical vent site, if not secured properly, can lead to catastrophic and uncontrollable bleeding.