Cardiac Trauma

Pathophysiology

Most stab wounds of the heart result in acute pericardial tamponade, although occasionally, rapidly exsanguinating hemorrhage may result. The patient thus usually presents with symptoms and signs of acute cardiac tamponade complicated by acute blood loss. (For a discussion of cardiac tamponade, see “ Acute Cardiac Tamponade ” under Clinical Features and Diagnostic Criteria in Section I of Chapter 23 .)

Missile wounds usually result in acute hemorrhagic shock, which may be rapidly fatal. If not, the patient enters the hospital profoundly hypotensive, with tachycardia and collapsed veins.

Penetrating cardiac wounds are frequently accompanied by wounds involving the pleural space, the intrapericardial thoracic vessels, the lung, and occasionally by wounds of the liver and other abdominal viscera.

Symptoms and Signs

External evidence of a penetrating wound is usually apparent, although in the case of injury with a stiletto, the external wound may initially escape discovery. The external wound and evidence for either hemorrhagic shock or acute pericardial tamponade dominate the clinical presentation.

Special Studies

If the patient's condition permits, a chest radiograph is made. In the rare situation of an initially stable patient, or in a patient recovering from repair of a penetrating wound in another organ and now suspected of having also suffered a cardiac laceration, usual techniques of cardiac investigation are used. Two-dimensional echocardiography, particularly transesophageal echocardiography (TEE), is the technique best adapted to these situations. Its use minimizes, in nonemergency situations, subxiphoid exploratory pericardiotomy.

Stab Wounds

Patients with stab wounds of the heart and great vessels usually survive when treatment is adequate, except for those in extremis on admission (most of whom have suffered immediate massive hemorrhage from laceration of a great vessel).

If the stabbing device is still in place when the patient is admitted to the emergency department, it is not removed until the incision is made and ideally not until the pericardium is opened.

When the patient arrives in the emergency department unconscious and without vital signs or semiconscious with gasping respirations, a thready pulse, and no blood pressure, and all evidence points to a cardiac or great vessel wound as the cause, prognosis is poor; immediate thoracotomy (see discussion under “ Missile Wounds ” later in this chapter) is indicated if the emergency department is prepared for this type of major surgery. If not, a large-bore needle (13F) is inserted into the pericardial space through the subxiphoid route, and the patient is transported rapidly to an operating room. Because of the pathophysiology of acute cardiac tamponade (see Chapter 23 ), removal of even 40 to 50 mL of blood usually improves the hemodynamic state, at least temporarily. When the patient is in shock but has vital signs, a pericardiocentesis is performed as described, followed by rapid transfer to the operating room. When the patient's condition is stable and a cardiac stab wound is only suspected, investigation can be accomplished in the emergency department or in the operating room if a noncardiac procedure is indicated. This evaluation is best performed by TEE.

Once in the operating room, the patient is rapidly anesthetized, prepared, and draped for operation. A large-bore needle is placed in an easily accessible large vein as these preparations are being made. Surgical draping should be wide, with the chest and abdomen fully exposed. Median sternotomy is made and the pericardium opened. (In institutions in which cardiac surgery is not frequently performed, an anterolateral incision, usually left-sided, is made, because this incision can be made rapidly and is the most generally useful.)

Blood is rapidly aspirated from the pericardial space with high-vacuum suckers. Ventricular wounds are best controlled initially by digital compression. Atrial and caval wounds are generally not well controlled in this manner, and wide Allis (Allis-Adair) clamps serve ideally to establish hemostasis by apposing the wound edges. If this is not possible or if the wound edges tear after application of clamps, a Foley catheter with a large balloon volume can be inserted into the cardiac chamber or vein and inflated. Only after digital or instrumental control of active bleeding has been accomplished should attention be turned to suturing the wounds. At this time, physiologic resuscitation should be completed. Blood volume is reconstituted with donor-specific matched or unmatched type O-negative blood to augment previously infused crystalloid or colloid, and blood pH is restored toward normal with bicarbonate. Supplemental calcium is usually given.

Ventricular wounds are best sutured with interrupted pledgeted mattress sutures of No. 2-0 or 3-0 polyester or polypropylene. A great danger in myocardial lacerations is their enlargement by the act of passing sutures in a fully filled and beating ventricle. It is often appropriate to induce inflow occlusion to empty the heart and provide a quieter field. After an interval of hyperventilation, the vena cavae are occluded using vascular clamps, followed by clamp occlusion of the ascending aorta after the heart has emptied a few beats later. The cardiac wound is sutured over the next 2 to 3 minutes; thereafter, the caval and aortic clamps are released. The heart will have continued to beat slowly during the occlusion period. Occasionally, a ventricular laceration is so extensive that it requires cardiopulmonary bypass (CPB) and patch-grafting of the ventricular free wall. Wounds near a major coronary artery are similarly sutured, with pledgets on both sides of the artery and the sutures passing beneath it. If the left anterior descending coronary artery has been damaged, a coronary artery bypass graft should be placed (see Chapter 7 ). Atrial or caval wounds are closed by continuous No. 4-0 or 5-0 polypropylene sutures. Suturing is done beneath the clamp or carefully over the top of the inflated balloon of a Foley catheter, and the clamp is removed (or balloon deflated) only after the suture line is largely in place.

Unless there is near certainty that the pleural spaces have not been violated, both are opened widely through the median sternotomy. The internal thoracic arteries, a potential source of hemorrhage, are examined and, if damaged, are suture-ligated. Damaged areas of lung are oversewn or stapled. The hilum of each lung is examined for injury to the pulmonary vessels.

Drainage catheters are placed in each pleural space (see “ Positioning Chest Tubes ” under Completing Cardiopulmonary Bypass in Section III of Chapter 2 ), and one may be placed in the pericardial space as well. If hemostasis within the pericardium has been satisfactory, the pericardium is loosely closed with widely spaced interrupted sutures. The sternotomy is closed in the usual manner (see Section III of Chapter 2 ).

Missile Wounds

Patients with missile wounds of the heart are far less likely to survive than those with stab wounds. Patients who are unconscious or without vital signs, or who are semiconscious but without a measurable blood pressure, should receive immediate thoracotomy if the emergency room is properly prepared. A left anterolateral incision is made, curving beneath the breast, and the thorax is entered through the fifth or sixth interspace. An assistant spreads the wound with two handheld retractors, or a self-retaining thoracotomy retractor is inserted, and digital control of the hemorrhage is obtained. If trained surgeons are in attendance and the repair appears to be a simple one, repair is then performed. Otherwise, the patient is transferred to a prepared operating room while digital control of the hemorrhage is maintained. If digital control of the hemorrhage is not possible, survival is unlikely and any further intervention inadvisable.

Patients not meeting these criteria for operation in the emergency department are transported immediately to the operating room. Principles of management are the same as described for penetrating wounds, but the result is less often successful.