Papillary muscle rupture and pericardial injuries after blunt chest trauma

Abstract

Non-penetrating cardiac trauma resulting in mitral valve rupture is uncommon, requiring a high degree of suspicion for diagnosis. Sudden and severe mitral regurgitation, unless surgically corrected rapidly lead to congestive heart failure and death. We report a patient with traumatic rupture of the antero–lateral papillary muscle of the mitral valve and pericardial injury, after a lateral blunt chest trauma, who successfully underwent emergency mitral valve replacement.

Chest trauma, Mitral valve regurgitation, Pericardial tear

1 Introduction

In earlier times, cardiac rupture was the only sequela of blunt chest trauma that received a surgical treatment although the first case of traumatic rupture of mitral valve papillary muscle was reported in 1936 by Glendy and White [1], but only in 1964 McLaughlin [2] reported the first successful repair of a mitral valve after a blunt trauma in a 7-year-old boy.

Focusing on valvular apparatus sequelae in post-traumatic settings, the lesions that generally occur consist in: contusion, laceration and rupture.

After blunt chest trauma papillary muscle rupture is uncommon, it's impossible to forecast clinical presentation and standard anatomic features because of native mitral valve and apparatus variability, and manifold types, directions and violence of trauma.

2 Case report

A 41-year-old man was found by emergency medical team to be unresponsive after a traffic accident. The patient was unseated from his motorbike and crashed to the ground, with a lateral impact. He was found unconsciousness and physical examination showed no external wounds on the chest, blood pressure was 80/50 mmHg, pulse rate 115 bpm. Mechanical-assisted ventilation after tracheal intubation was started and the patient was transported to the local hospital, where he had an electrocardiogram that showed sinus tachycardia without any pathological disturbance. A chest X-ray demonstrated a large globular heart and a computed tomographic scan revealed pneumomediastinum with pulmonary contusion. Left tibial and fibular disarranged fractures were immediately treated. Because of progressive haemodynamic worsening and appearance of holosystolic murmur radiating to the axilla, a transthoracic-echocardiogram was done demonstrating a flail anterior mitral leaflet with severe mitral regurgitation and normal systolic function.

At the arrival, in our cardiac surgery Center, he was on low output syndrome, despite inotropic support, with a blood pressure of 55/35 mmHg.

Diagnosis of acute mitral regurgitation due to antero–lateral papillary muscle avulsion was confirmed by transesophageal echocardiography. The patient underwent emergency cardiac surgery.

Chest was opened through a mid-line sternotomy. Hematoma of the remnant thymus gland was noted. At the opening of the anterior pericardium the heart was hyperdynamic, swollen and stretched without macroscopic lesions. A pericardial tear with large communication between pericardial cavity and left pleural space was found.

Standard cardiopulmonary bypass with bicaval cannulation was instituted, patient was cooled down at 32°C, the aorta was cross-clamped and cold hematic cardioplegia was given for myocardial protection. An atrial trans-septal approach was used and examination of the mitral valve revealed a complete detachment of the head of tethered antero–lateral papillary muscle with rupture of accessory chordae tendinae. The flailing anterior mitral leaflet was resected (Fig. 1) , while the posterior leaflet was left in place, and a #. 27 bicarbon (Sorin Biomedica SPA, Saluggia VC, Italy) mechanical valve, was implanted.

Fig. 1

Anterior leaflet of the mitral valve, with attached the head of antero–lateral papillary muscle, and rupture of accessory chordae tendinae.

Weaning from cardiopulmonary bypass was easy but patient received high-dosage inotropic support, that was successfully discontinued on the 3rd post-operative day.

At the time of operation laboratory tests showed: creatine phospho kinase (CPK) was 2463 units/l and CPK MB fraction 11 units/l with a peak on the 2nd post-operative day of CPK 2800 units/l and CPK-MB 62.8 units/l.

The patient had an uneventful recovery and was discharged home on 13th postoperative day.

3 Discussion

The clinical spectrum of cardiac injuries after blunt chest trauma varying from myocardial contusion to valvular rupture. Currently, it has increased in frequency because of the higher incidence of motor vehicle collisions; nevertheless both the incidence and severity are underestimated. The severity of chest wall injury seems not to have a direct relationship with the occurrence of cardiac trauma. When a cardiac valve is involved, most frequently is the aortic valve, followed by the mitral and tricuspid. Mitral valve rupture associated with pericardial tears is an exceptionally rare event.

Valve and subvalvular apparatus of the mitral valve are most vulnerable during late diastole or early systole; if a sudden increase in intrathoracic pressure is transmitted to the ventricle chamber, during this period, tremendous stress may develop accounting for papillary muscle head or chordal rupture.

The rarity of mitral valve trauma is proven by the fact that Parmley and co-workers [3], in their 546 autopsy of fatal non-penetrating cardiac injuries, found no isolated mitral lesions and only eight patients with pure mitral valve disruption either of the leaflets, chordae tendinae or papillary muscles, in association with other cardiac injuries.

Numerous clinical cases of unrepaired mitral insufficiency have been reported in literature; a review of the literature yielded 36 reported cases of surgically corrected traumatic mitral injury (Table 1)

Table 1

Reported cases of surgically corrected traumatic mitral injury

In the past years serial electrocardiograms and enzyme measurements have been the diagnostic methods; nowadays echocardiography both transthoracic (TTE) or transesophageal (TEE) has provided a real-time window for assessing myocardial injury and function. TEE offers higher resolution of sonography, the possibility of differential diagnosis and can be performed quickly, safely at bedside, unrespective to patient's conditions, habitus or position; this results in a significant reduction between injury time, diagnosis and treatment [4].

Clinical findings of patients with traumatic mitral injury varying from acute cardiogenic shock to whom that remain asymptomatic for years. Surgery is dictated by the extent and location of damage, presence of hemodynamic deterioration and associated injuries.

Literature overview demonstrate that many surgical approaches have been proposed for treating mitral rupture, ranging from primary repair and different techniques of reconstruction, to replacement with a prosthetic valve [4–6]. The decision to replace or to preserve a native valve must be individualized based on patient's mitral apparatus anatomical features, extent of damage and estimated probability of success [7].

We decided for mitral valve replacement because of intraoperartive anatomical papillary muscle findings and considering that cardiac injuries sequelae may appear after several days from accidents, because muscular contusion evolving into necrosis can produce a subacute cardiac rupture [8].

Then reparative solution for post-traumatic valvular apparatus in this setting represent a probable risk factor of primary surgical failure.

4 Conclusion

Patients presenting with severe blunt chet trauma should undergo cardiac examination to exclude injuries to cardiac structure. We suggest that those patients should routinely undergo TTE or TEE that in our hands proved to be the most reliable and accurate diagnostic tool.