Right-to-left flow through a patent foramen ovale in acute right ventricular infarction. Two case reports and a proposal for management

Optimal Conservative Management Resolves Refractory Hypoxemia in Patient with Right Myocardial Infarction Complicated by PFO-Induced Shunting

Inferior myocardial infarction is often accompanied by infarction of the right ventricle (RV). Uncommon RV infarction cases with patent foramen ovale (PFO) shunt, leading to severe persistent hypoxemia even without any pulmonary embolism involvement and often requiring invasive intervention, have been documented previously. We report a patient with RV infarction and right-to-left shunt via PFO who improved with only early revascularization and optimal standard treatment. This condition may not necessitate any invasive intervention if it is treated and monitored per standard procedures. Clinicians should consider the possibility of a right-to-left shunt in patients with RV infarction and persistent hypoxemia to implement appropriate therapeutic interventions.

Profound Hypoxemia From Right Ventricular Failure Following Acute Type A Aortic Dissection

Acute aortic dissection is a catastrophic event with high mortality rate if left untreated. Complications of aortic dissection are fairly common, and some of them increase mortality rates further, necessitating early diagnosis and treatment. We present a case of Stanford type A aortic dissection with an uncommon complication of right ventricular failure, which resulted in a rare presentation of persistent hypoxemia despite intubation and maximal ventilatory support. Other common causes of hypoxemia were ruled out and this was eventually attributed to the aortic dissection and emergency surgery was arranged for the patient. Our case can help to increase the awareness of such a potential association, which should be considered in future similar clinical situations, thus minimizing any delay in management.

Intracardiac Right-to-Left Shunt Complicating Right Ventricular Failure

Three cases of intracardiac right-to-left shunt at the atrial level complicating right ventricular failure (RV) are described. Severe hypoxemia resulted in 2 patients and stroke in the third. This was a consequence of right ventricular infarction causing right-sided heart failure resulting in high right-sided pressures. Echocardiography demonstrated the shunts. A review of the literature on this uncommon problem suggested management strategies based on the limited experience with this condition.

Pulmonary Thromboendarterectomy for Chronic Thromboembolic Pulmonary Hypertension

Pulmonary thromboendarterectomy is the most effective therapy for chronic thromboembolic pulmonary hypertension. The pathophysiology, anesthetic management, and perioperative outcomes of patients with chronic thromboembolic pulmonary hypertension undergoing pulmonary thromboendarterectomy are reviewed.

Transient right-to-left intracardiac shunt following a right ventricular myocardial infarction

A 56-year-old smoker presented with a 3-day history of intermittent chest pain. Cardiovascular examination on admission was normal. ECG showed minimal (<1 mm) ST elevation in lead III, and right-sided leads revealed similar mild ST-elevation. Troponin I was elevated at 10.91. He was managed as a delayed-presentation ST-elevation myocardial infarction case. 12 h following admission, he developed oxygen-resistant hypoxia and hypotension. There were no clinical or radiological signs of pulmonary congestion. CT pulmonary angiogram revealed no pulmonary embolus. A bubble-contrast echocardiogram confirmed an active interatrial right-to-left shunt without Valsalva provocation. His hypoxia steadily improved over the following 24 h and he did not require any shunt closure. A repeat bubble contrast echocardiogram showed that the shunt was now only active following a Valsalva manoeuvre. Transoesophageal echocardiography confirmed a patent foramen ovale. This is a rare but important cause of resistant hypoxia following a right-heart infarct.

Acute right to left shunt through patent foramen ovale presenting as hypoxemia after myocardial infarction: a case report

Introduction

This is a report of a 56-year-old man who became hypoxic due to an acute right to left shunt after sustaining a myocardial infarction involving the right ventricle. This case provides the opportunity to review several key pathophysiologic concepts in the setting of acute right ventricular infarction. Although the development of an acute right to left shunt is a rare complication of myocardial infarction, it is important to recognize the diagnosis early in order to prevent life threatening or debilitating clinical sequelae that may result from tissue hypoxia and embolic events. Transesophageal echocardiography is the noninvasive study of choice to confirm the diagnosis. Treatment involves optimization of right ventricular function to minimize shunting. However, medical therapy may provide only temporary relief, and closure of the atrial septal defect should be considered if a clinically significant shunt persists.

Case presentation

A 56-year-old Caucasian man with severe aortic insufficiency presented to the emergency department for evaluation of substernal chest pain. An inferior myocardial infarction was diagnosed by the electrocardiogram and serologic markers. Cardiac catheterization revealed complete occlusion of the right coronary artery as well as a 50-75% stenosis of the left anterior descending artery. Angioplasty of the right coronary artery was performed, but immediate re-occlusion occurred. Subsequently, hypotension and severe hypoxemia developed and persisted despite intubation and mechanical ventilation with 100% oxygen. A significant right-to-left shunt through a patent foramen ovale was diagnosed by contrast transesophageal echocardiogram. Surgical intervention was required and included coronary artery bypass grafting, aortic valve replacement as well as closure of his atrial septal defect.

Conclusion

A right to left atrial shunt is a rare complication of inferior myocardial infarction with right ventricular infarction. The diagnosis should be considered in the presence of inferior myocardial infarction when hypoxemia persists despite administration of 100% oxygen. Early diagnosis and treatment are critical in order to reduce the risk of embolization and to prevent end-organ damage due to hypoxemia.

Tricuspid valvular papillary muscle rupture with intractable hypoxia: a rare complication post MI

Acute inferior ST-elevation myocardial infarction (STEMI) alone contributes to approximately 10% of in-hospital mortality due to ischemic heart disease. Right ventricular involvement occurs in 50% of patients who present with inferior STEMIs, increasing in-hospital mortality to 31%. In the setting of concomitant severe tricuspid regurgitation, acute rupture of the papillary muscles within the right ventricle should be considered in the differential diagnosis. The authors present the case of a patient with intractable hypoxia in the setting of an acute inferior STEMI complicated by rupture of the posterior tricuspid valve papillary muscle.

Percutaneous closure of patent foramen ovale: impact of device design on safety and efficacy

OBJECTIVE

To compare the safety and efficacy of percutaneous closure of patent foramen ovale (PFO) with the Amplatzer PFO occluder (Amplatzer) or the PFO STAR device (STAR) in patients with presumed paradoxical embolism.

METHODS

Implantation characteristics, procedural complications, residual shunt, and recurrence of thromboembolic events were recorded prospectively in 100 consecutive patients undergoing percutaneous PFO closure with the STAR (n = 50) or Amplatzer (n = 50) devices between 1998 and 2001. The study was not randomised. Device implantation was successful in all cases.

RESULTS

There were more procedural complications in the STAR than in the Amplatzer group (8/50 v 1/50, p = 0.01). More than one device placement attempt was an independent predictor of procedural complications (odds ratio (OR) 8.5, 95% confidence interval (CI) 1.3 to 55.8; p = 0.03). A residual shunt six months after PFO closure, assessed by transoesophageal contrast echocardiography, occurred more often in the STAR than the Amplatzer group (17/50 v 3/50, p = 0.004), and was predicted in the STAR group by the use of a device with a 5 mm as opposed to a 3 mm disc connector (OR 6.1, 95% CI 1.1 to 34.0; p = 0.04). The actuarial risk of recurrent thromboembolic events after 3.5 years was 16.8% (95% CI 7.6% to 34.6%) in the STAR and 2.7% (95% CI 0.4% to 17.7%) in the Amplatzer group after three years (p = 0.08).

CONCLUSIONS

Percutaneous PFO closure with the Amplatzer PFO occluder had fewer procedural complications and was more likely to be complete than with the STAR device. These findings underline the importance of device design for successful percutaneous PFO closure.

Right-to-left shunting through a patent foramen ovale in right ventricular infarction: improvement of hypoxemia and hemodynamics with inhaled nitric oxide

Inhaled nitric oxide is a selective pulmonary vasodilator that has been used successfully to treat hemodynamic embarrassment and right-to-left interatrial shunting in acute right heart failure. Previous reports have been in the setting of disorders causing elevated right heart afterload, such as pulmonary embolism, acute respiratory distress syndrome, and chronic obstructive pulmonary disease. Right ventricular infarction is a less common, but important cause of acute right heart failure with which the intensivist should be familiar. We report a patient with right ventricular infarction for whom cardiogenic shock and refractory hypoxemia due to right-to-left interatrial shunting were effectively treated with inhaled nitric oxide. The potential for broader application of inhaled nitric oxide as a therapy for right ventricular infarction is discussed.

Crossing atrial thrombus in a patient with recurrent pulmonary embolism

OBJECTIVES

To report the detection of a thrombus entrapped in a patent foramen ovale by echocardiography in a patient with recurrent pulmonary embolism.

DESIGN

Case report.

SETTING

Intensive care unit of a university hospital.

PATIENT

A 62-yr-old man with initial deep venous thrombosis and recurrent minor pulmonary embolism followed by a severe embolic event with transitory hemiparesis 10 days after prostatectomy.

INTERVENTION

Systemic anticoagulation, surgical removal of a crossing atrial thrombus, closure of a patent foramen ovale, and venous thrombectomy.

MEASUREMENTS AND MAIN RESULTS

Transesophageal echocardiography revealed a large thrombus entrapped in a patent foramen ovale with portions in all four heart chambers. Intraoperatively, a 19-cm-long thrombus, shaped like the pelvic veins, was found. The patient was successfully weaned from cardiopulmonary bypass, requiring temporary positive inotropic support because of right ventricular dysfunction. Within 24 hrs of the operation, the patient was discharged to the intermediate care unit.

CONCLUSIONS

Recurrent pulmonary embolism can potentially result in paradoxic embolism in patients with a patent foramen ovale. In such patients, it may be crucial to monitor right ventricular function and exclude right-to-left shunts by transesophageal echocardiography, regardless of clinical symptoms. The patent foramen ovale should be closed. This case emphasizes an important indication for transesophageal echocardiography in critically ill patients.