Sudden death due to spontaneous rupture of the right atrium in the setting of chronic lung disease: A case report and review

Introduction

A clinical condition known as cardiac tamponade is brought on by a rapid build-up of blood, pus, other fluids or gas in the pericardial space, which causes an increase in intra-pericardial pressure. The amount of venous blood returning to the heart is constrained because the rising pericardial pressure exceeds the central venous pressure; hence, no blood will be pumped out by the heart in systemic circulation. Accumulation of blood in the pericardial cavity leads to haemopericardium, which is usually due to ventricular wall rupture but may also be due to atrial rupture. The term atrial rupture denotes a complete, acquired defect of the wall of either atrium through which blood may leak into the pericardial sac. The first atrial rupture case was published by Rutherfoord in 1828. ¹ Since then, very few cases of isolated right atrial ruptures have been reported. The paucity in the relevant literature could primarily be attributed to the high on-scene fatality rate of isolated right atrial rupture (IRAR). ² The common causes of IRAR are blunt-force trauma followed by various pathological conditions of the heart but our case is the sudden death of an adult male due to a spontaneous, isolated rupture of the right atrial wall without any trauma or gross or microscopic pathology to the heart wall. A search was conducted using PubMed, Ovid and the Cochrane Library, but no case similar to this one was found.

Case report

A 32-year-old man was brought unconscious to the emergency room. His vitals were not recordable. CPR was tried but the patient could not be revived and was declared dead. There was an alleged history of sudden onset of uneasiness and giddiness, followed by unconsciousness at lunch time, about 45 minutes before his arrival at the hospital. He had been a chronic smoker for over 10 years. At autopsy, the pericardium was found to be tense with a bluish appearance (Figure 1(a)), due to underlying blood. Opening the pericardium, free and clotted blood was found covering the heart from all sides (Figure 1(b)). The right atrial wall had ruptured on the posterior aspect near the ventricle (Figure 1(c)). The right atrium was grossly normal without any softening, necrotic changes or bruise. Effusion of blood was found in the sub-epicardial region near the atrio-ventricular groove, mainly on the right side. Both lungs were found adherent to the chest wall due to fibrosis, and multiple pus pockets were found in places in the cut sections of both lungs. In histopathological examination, no findings were suggestive of infarction in the right atrium (Figure 2(a)) or right coronary artery (Figure 2(b)). Dilated and disrupted alveoli filled with eosinophilic fluid along with acute and chronic inflammatory cells were found in lung tissue (Figures 2(c) and 2(d)). All the organs were pale. Haemopericardium, as a result of a right atrial wall rupture, was determined as the cause of death.

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Figure 1.

Gross examination. (a) A tense pericardium with a bluish appearance due to haemopericardium. (b) Clotted blood covering the heart from all sides and (c) A right atrial wall rupture on the posterior side near the ventricle.

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Figure 2.

Histopathological examination. (a) No sign of an infarction or any pathology of the right atrial wall. (b) Atherosclerotic changes with less than 20% lumen obstruction. (c) Microscopic examination with 100× magnification, showing eosinophilic material filling the alveoli with inflammatory cells and (d) Microscopic examination with 400× magnification, showing both acute and chronic inflammatory cells in lung tissue along with disruption of the alveoli.

Discussion

Trauma, atrial infarction, fatty degeneration of the muscle, valvular heart disease, tumour of the heart, or aneurysm of the atrium, are usually linked to or precede atrial rupture. ³ Several instances are included under the category “miscellaneous”, whose aetiology cannot be determined due to insufficient description. Yun et al. described a case of a newborn infant, who had IRAR as a result of high-pressured descent through the vaginal wall during birth, to demonstrate the range of IRAR aetiologies. ⁴ The vast majority of cases report motor vehicle accidents as the source of blunt trauma. ⁵ In our case, neither the deceased's medical history nor any conclusive evidence points to any trauma. Although an acute myocardial infarction may raise the risk of cardiac rupture, this population has less than 1% rupture frequency, making it very difficult to find a relationship. ⁶ Furthermore, the left ventricle or the interventricular septum, but not the right atrium, will most likely be affected by a rupture of an infarcted heart wall. ⁶

It was once believed that all of the heart's chambers were equally liable to rupture, but more recent autopsy studies have questioned this after discovering that the right chamber appeared to rupture more frequently. ⁷ Cardiovascular rupture happens in the right atrium, the weakest region of the heart, when intraluminal pressure exceeds the elasticity of the cardiac wall.^8,9 The auricle of the right atrium is the site of IRAR that occurs most frequently which is mostly explained by its thin wall. ¹⁰ In our case, the right atrial rupture did not occur where the auricle would have been. The great majority (92%) of IRAR cases were brought on by motor vehicle accidents. ¹¹ Right atrial rupture frequently manifests as haemopericardium, which is then followed by a haemothorax if there is a pericardial tear. ¹¹ A significant increase in intraluminal pressure also occurs in any heart rupture. The substantially lower intraluminal pressure of the atria, which fluctuates from −2 to +2 mmHg in the right atrium and is only marginally greater in the left atrium, appears to be strongly associated with the decreased incidence of atrial rupture as opposed to ventricular rupture. The right atrium is a low-pressure chamber, so a large amount of clotted blood covering the heart from all sides was found due to the slow accumulation of blood in the pericardial cavity.

Patients with pulmonary disease or valvular heart disease may have significantly greater atrial pressures.^12,13 In our case, both lungs were found adherent to the chest wall, with small pus pockets at some places. On microscopic examination, inflammatory cells in the lungs, eosinophilic fluid in alveoli, and alveolar disruption in chronic smokers suggest that the deceased had chronic lung disease with emphysematous changes. This may account for an increase in the intraluminal pressure of the heart and rupture at the weakest point during the act of mastication. A common complication of chronic lung disease (CLD) is pulmonary hypertension. When it develops, the prognosis is poor, and it may lead to right heart failure. ¹⁴ In our case, pulmonary hypertension due to chronic lung disease may be a contributing factor to spontaneous IRAR.

Infarction of the atrial wall due to an obliterative endarteritis or thrombotic occlusion is not an unusual cause of spontaneous rupture of the atrium, as it makes the cardiac wall soft and weak due to infarction changes, and an increase in intraluminal pressure increases the chances of the heart rupturing. In our case, no findings suggestive of right atrial wall pathology were found on gross and microscopic examination. The right coronary artery showed atherosclerotic changes, but they are not significant as they blocked less than 20% of the lumen. Here, gross and microscopic findings suggestive of chronic lung disease may offer a reason for the raised intraluminal pressure of the heart chambers. Sub-epicardial effusion of blood along the atrio-ventricular grove is probably due to chest compression at the time of cardio-pulmonary resuscitation (CPR) in the emergency ward.

Conclusions

Most deaths from right atrial rupture result from blunt-force trauma. Isolated right atrial rupture, in the absence of any other injuries or heart wall pathology, is a very unusual cause of sudden death. In the emergency room, it's critical to evaluate these situations objectively because chest compressions during CPR may exacerbate the patient's condition. Beck triad, which includes an engorged neck vein, muffled heart sound and low blood pressure, should alert for the possibility of cardiac tamponade. At autopsy, if IRAR is found without any trauma, the heart should be sent for histopathological examination for heart wall pathology that could be the cause of the atrial wall's weakening. Lung tissue pathology like chronic lung disease and vessel pathology like pulmonary embolism, which may raise intraluminal pressure, should also be looked out for on gross and microscopic examination. IRAR is a very rare finding, so a multicentric study is needed to find out the factors associated with spontaneous rupture of just the right atrial wall.