Patent foramen ovale: a cause of hypoxemia in patients on left ventricular support

Left ventricular assist device placement in the setting of congenital VSD

We describe the management of a 59-year-old female with an unrepaired congenital ventricular septal defect (VSD) and end stage nonischemic cardiomyopathy necessitating placement of a left ventricular assist device (LVAD) as a destination treatment. Simultaneous repair of the VSD was performed during the LVAD implantation under a beating heart. The patient remained hemodynamically stable throughout her postoperative course, without signs of hypoxia or cyanosis. Following discharge, outpatient surveillance echocardiogram demonstrated successful VSD closure and no residual shunt.

Anesthetic and Perioperative Considerations in Patients Undergoing Placement of Totally Implantable Replacement Hearts

The recent successful implantation of the AbioCor im plantable replacement heart at the Rudd Heart-Lung Institute, Jewish Hospital, Louisville, KY, has renewed clinical interest in the use of the mechanical replace ment heart as therapy for intractable heart failure. Al though the number of orthotopic heart transplants has plateaued in the past decade, the number of patients requiring transplantation continues to increase. This supply/demand discrepancy continues to be the main catalyst for the research and development of other therapies for the failing heart. This review addresses perioperative considerations, monitoring modalities, and perioperative therapeutic interventions that may help guide the cardiac anesthesiologist through the challenges presented by implantation of total replace ment hearts in end-stage cardiac patients.

Unusual cause of hypoxemia after automatic implantable cardioverter-defibrillatorleads extraction

The indication of pacemaker/AICD removal are numerous. Serious complication can occur during their removal, severe tricuspid regurgitation is one of the complication. The occurrence of PFO is not uncommon among adult population. Shunting across PFO in most circumstance is negligible, but in some necessitates closure due to hypoxemia. We report a case of 62 year old man, while undergoing AICD removal, had an emergency sternotomy for cardiac tamponade. Postoperatively, he experienced profound hypoxemia refractory to oxygen therapy. Transthoracic Echocardiogram was performed to rule out intracardiac shunts at an early stage, but it was difficult to obtain an good imaging windows poststernotomy. A small pulmonary emboli was noted on CTPA, but was not sufficient to account for the level of hypoxemia and did not resolve with anticoagulation. Transesophageal echocardiogram showed flail septal tricuspid valve with severe TR and bidirectional shunt through large PFO. Patient was posted for surgery, tricuspid valve was replaced and PFO surgically closed. Subsequently, patient recovered well ad was discharged to home. Cause of hypoxemia might be due to respiratory or cardiac dysfunction. But for hypoxemia refractory to oxygen therapy, transoesophageal echocardiogram should be always considered and performed early as an diagnostic tool in post cardiac surgical patients.

Amplatzer™ occlusion device implantation in a patient with biventricular HeartWare®

There have been several reports of right-to-left shunting through patent foramen ovale (PFO) after implantation of a left ventricular assist device (LVAD). The atrial pressure changes after assist implantation leading to revelation of undetected PFOs may cause severe systemic hypoxemia. A percutaneous closure approach has been shown to be an adequate therapy option in patients with LVAD. We report a successful interventional occlusion of a PFO with right-to-left shunt in a patient with biventricular HeartWare® ventricular assist device (HVAD) support.

Severe hypoxaemia with a left ventricular assist device in a minipig model with an undiagnosed congenital cardiac disease

We describe the placement of a left ventricular assist device (LVAD) in a pig with spontaneously occurring atrial septal defect (ASD) (incidental finding) that created a right-left cardiac shunt, with subsequent severe hypoxaemia. Early diagnosis was critical in order to prevent end-organ damage due to hypoxaemia. Adequate monitoring alerted us to the deterioration in oxygenation, haemodynamics and cerebral oxygen metabolism. This forced us to change the level of assistance provided by the pump, and thus dramatically correct this impairment. Necropsy revealed an ostium secundum ASD. In conclusion, if hypoxaemia presents after implementation of an LVAD, the presence of a right-left shunt must be ruled out. The first step must be a judicious reduction in assist device flow to minimize intracardiac shunting. Subsequently, atrial septal closure of the defect should be considered. We report an experimental model of severe hypoxaemia after placement of an LVAD as part of a larger research project.

Use of gated cardiac computed tomography angiography in the assessment of left ventricular assist device dysfunction

The purpose of this study is to describe the utility and limitations of gated contrast-enhanced cardiac computed tomography angiography in assessing left ventricular assist device function. Computed tomography angiography (CTA) was used in 14 patients with left ventricular assist devices (LVADs) who had persistent heart failure symptoms, hemodynamic instability, or potential problems with LVAD flows. Retrospectively gated contrast-enhanced CTA was performed on 64-detector scanner, and the CTA images were postprocessed in multiple curved projections on TeraRecon workstation. This study describes the use of CTA to identify LVAD-related issues that altered clinical management and explores the role of CTA and other techniques in evaluating LVAD function. Six of 14 LVAD patients who demonstrated no abnormality on CTA remained stable with medical management. In the remaining eight patients, CTA was abnormal, including abnormalities specifically related to the LVAD cannula. As a result of findings detected by CTA, six patients underwent surgical intervention, including device exchange and heart transplant. Computed tomography angiography is a noninvasive method that enhances diagnostic evaluation of patients with suspected LVAD dysfunction and can lead to changes in patient management.

Rescue treatment by percutaneous closure of interatrial septal defect or PFO in infants with Berlin heart

During the past two decades, important progress has been achieved in the treatment of end-stage congestive heart failure in newborns and infants. The use of ventricular assist devices (VAD) in these patients is now available as a bridge to heart transplantation. The use of a VAD may reveal the presence of a silent interatrial septal defect or a patent foramen ovale (PFO), inducing a right to left shunt resulting in systemic desaturation and hemodynamic instability. We present two cases of low weight infants on circulatory support with VADs and right to left shunt through interatrial septum that were successfully treated by percutaneous intervention with an occlusion device.

Managing drugs and devices in patients with permanent ventricular assist devices

Patients will be considered for destination mechanical circulatory support device (MCSD) implantation when all other organ-saving treatment options have failed and they are not eligible for heart transplantation. Current medical evidence suggests that only for those patients who are inotrope-dependent and therefore likely have a 1-year survival probability without MCSD implantation of less than 50%, MCSD intervention will add to survival and quality-of-life benefit. Suitable candidates for MCSD are those patients who have a high risk of dying from heart failure but acceptable noncardiac risk. Evaluation of patients for MCSD requires a systematic and critical review of all organ systems and of the psychosocial situation. Specifically, right ventricular function and risk of right ventricular failure should be evaluated before planning destination MCSD implantation. Treatment will focus on prompt recovery from MCSD implantation, maintaining optimal treatment for heart failure, and preventing/treating MCSD complications, including infection, bleeding, coagulopathy, right heart failure, and device dysfunction. MCSD programs should be organized as an advanced heart failure center directed by specialized heart failure cardiologists, surgeons expert at implant and management of MCSD, specialized nurses, social workers, psychologists, financial experts, and physical therapists. MCSD practice is based on a patient-centered theory, with an appropriate understanding of the respective roles of the physician and the patient during their iterative encounters in which the patient is an autonomous person making responsible personal health decisions while the health care team is providing continued expert and empathic counseling about various options, based on systematic outcomes research (eg, by participation in the Interagency Registry for Mechanically Assisted Circulatory Support - MCSD database ).

Percutaneous balloon catheter closure of a patent foramen ovale in a patient with pulmonary disease, profound hypoxemia, and normal right heart pressures

Right-to-left intracardiac shunting across a patent foramen ovale (PFO) has been reported in patients with pulmonary embolism, right ventricular (RV) infarction, positive pressure ventilation with positive end-expiratory pressure, heart failure with left ventricular assist devices, cardiac tamponade, and unilateral diaphragmatic paralysis. The primary driving force for these shunts is a reduction in the compliance of the pulmonary bed or right ventricle; right atrial pressure is usually elevated and pulmonary hypertension is frequently present. Significant shunting and hypoxemia are unusual in the absence of these diseases. We encountered a patient with normal pulmonary pressures, severe hypoxemia, pulmonary disease, and intracardiac shunting across a PFO in whom it was difficult to determine how great a role intracardiac shunting was playing in his hypoxemia. To assess this, we performed percutaneous balloon catheter occlusion of the PFO, using transthoracic echocardiography with contrast to confirm closure of the PFO. Therapeutic balloon occlusion has been reported in severe hypoxemia due to shunting across a PFO in a patient with RV infarction. Our case is unique, however, in two respects. First, this patient had normal right-sided cardiac pressures and normal RV function and, thus, no obvious driving force for a significant right-to-left shunt. Second, transthoracic echocardiography with contrast was used before and after balloon inflation to confirm closure of the PFO. This technique helped to answer the important clinical question of whether surgical closure of the PFO in this patient with both lung disease and intracardiac shunting would significantly improve his oxygenation.

The Incidental Finding of a Patent Foramen Ovale During Cardiac Surgery: Should It Always Be Repaired? A Core Review

With the increased use of intraoperative transesophageal echocardiography, patent foramen ovale (PFO) has become a common finding during heart surgery. This finding presents a difficult dilemma for cardiac surgeons, since the impact of intraoperatively diagnosed PFOs on postoperative outcome is unknown. Changes in the surgical plan required for closure of a PFO subject the patient to the possibility of additional risk. On the other hand, a decision to not close a PFO exposes the patient to unclear immediate and long-term consequences. Deciding whether or not to close a PFO currently depends on the clinicians' personal preferences, the probability of intraoperative and postoperative hypoxemia, and any anticipated deviation from the initial surgical plan. Most clinicians agree that an intraoperatively diagnosed PFO must be closed when surgery leads to a high risk of hypoxemia (e.g., left ventricular assist devices placement, heart transplantation); should be closed in most cases when minimal deviation from the initial surgical plan is needed for PFO closure (e.g., mitral valve or tricuspid valve surgeries); and probably, should be closed during heart surgeries performed without atriotomy and bicaval cannulation when the risk of perioperative or remote PFO-related complications is increased. The recent development of percutaneous methods of PFO closure provides a valuable backup for those cases when PFO is not closed and postoperative hypoxemia or other complications may be attributable to the uncorrected PFO.

Hypoxemia Complicating LVAD Insertion: Novel Application of the Amplatzer PFO Occlusion Device

We report a case of profound systemic hypoxemia complicating left ventricular assist device (LVAD) insertion due to right to left shunting through a patent foramen ovale (PFO) in association with a Chiari network. The patient was successfully managed with percutaneous closure of the interatrial defect using an Amplatzer PFO occlusion device and judicious reduction in LVAD flows.

Anterior Approach to Implant the Jarvik 2000 With Retroauricular Power Supply

The retroauricular power supply of the Jarvik 2000 (Jarvik Heart Inc, New York, NY) left ventricular assist device is suitable for permanent support, as it is associated with fewer infections than conventional drivelines. Implantation through a left-lateral thoracotomy limits the performance of additional cardiac procedures. We describe a technique that used a sternotomy for the implantation of the Jarvik 2000 with retroauricular power supply in two patients. The retroauricular power supply of the Jarvik 2000 can be provided with an anterior approach, allowing full surgical access to the heart. If the outflow graft to the ascending aorta indeed reduces aortic stasis and thromboembolic events, the anterior approach with retroauricular power delivery might evolve into a standard procedure.

Profound hypoxemia resulting from shunting across an inadvertent atrial septal tear after left ventricular assist device placement

Defects within the interatrial septum (IAS) can be a source of significant right-to-left shunting and hypoxemia, particularly after placement of a left ventricular assist device (LVAD). We report a case of LVAD placement in which an unrecognized IAS tear occurred intraoperatively, leading to profound arterial desaturation. Transesophageal echocardiography (TEE) was instrumental in making the diagnosis. Certain intraoperative events increased the pressure gradient between the right and left atria, aggravating hypoxemia. We recommend that patients undergoing LVAD placement be screened intraoperatively with TEE for unrecognized IAS defects. Re-examination of the IAS should occur on weaning from cardiopulmonary bypass.

IMPLICATIONS

A traumatic atrial septal defect after atrial cannulation caused a right-to-left intracardiac shunt on initiation of left ventricular assist device support that was further aggravated by chest closure and pleural suction, culminating in severe hypoxemia.

Anesthetic Management for Implantation of the Jarvik 2000??? Left Ventricular Assist System

The Jarvik 2000 Heart(TM) is a left ventricular assist device that produces continuous nonpulsatile axial flow by means of a single, rotating, vaned impeller. Anesthetic and perioperative considerations of the Jarvik 2000 Heart(TM) differ from those of conventional assist devices. The Jarvik 2000 is implanted within the left ventricle through a left thoracotomy, which is aided by left lung isolation. A brief period of cardiopulmonary bypass and induced ventricular fibrillation facilitate implantation. Transesophageal echocardiography is essential to assure proper intraventricular positioning of the device and aortic outflow, confirmed by observation of aortic valve opening in the presence of adequate left ventricular volume. Because continuous flow devices function best in the presence of lower systemic and pulmonary vascular resistance, milrinone was preferentially used as an inotropic drug. In the first group of 10 patients to receive the Jarvik 2000, the pump provided a cardiac output of up to 8 L/min, depending on preload, afterload, and pump speed. There were no early perioperative deaths. The average support duration was 81.2 days; the range was 13-214 days. Seven of the 10 patients survived to transplantation. Survivors underwent complete physical rehabilitation during pump support.

IMPLICATIONS

The Jarvik 2000 is a left ventricular assist device that produces continuous nonpulsatile axial flow by means of a rotating, vaned impeller. Because the anesthetic considerations differ from those of conventional left ventricular assist devices, we report the perioperative management of the first 10 patients who participated in a bridge-to-transplantation feasibility study of the Jarvik 2000.

[Perioperative implications of heart transplant]

Over the past 30 years, heart transplantation has evolved into a definitive therapy for patients with end-stage cardiomyopathy. However, perioperative management of patients undergoing heart transplantation remains a challenge for anesthesiologists. The presence of biventricular failure, arrhythmias and associated multisystem organ dysfunction may contribute to significant intraoperative hemodynamic instability prior to the initiation of cardiopulmonary bypass (CPB). Even after an uneventful transplantation, weaning from CPB may be difficult. Acute right ventricular failure can develop in the recipient secondary to pre-existing pulmonary hypertension. Treatment options frequently focus on therapeutic interventions directed towards decreasing pulmonary vascular resistance and improving right ventricular contractility. Intraoperative use of transesophageal echocardiography (TEE) enables the anesthesiologist to diagnose acute right ventricular failure early on and guide therapy. Concurrent pathology including kinking of the pulmonary artery anastomosis or valvular insufficiency in the transplanted heart can also be recognized and addressed. The number of patients undergoing cardiac transplantation is continually increasing. In addition, the use of more effective immunosuppressive agents has curtailed transplant rejection and permitted longer survival. Consequently, heart transplant recipients are more frequently presenting for non-cardiac surgical procedures. Thus, an understanding of physiological and pharmacological implications associated with heart transplantation is crucial for managing these patients in the perioperative period.

Timing of transesophageal echocardiography in diagnosing patent foramen ovale in patients supported with left ventricular assist device

Left ventricular assist devices unload the left ventricle and decrease left atrial pressure. This hemodynamic change may cause a right to left atrial shunt and hypoxemia in patients with patent foramen ovale. We prospectively studied the best time for performing diagnostic transesophageal echocardiography in left ventricular assist device patients. Intraoperative transesophageal echocardiography was performed in 14 patients before cardiopulmonary bypass was initiated and after left ventricular assist device was implanted. No patent foramen ovale was detected when transesophageal echocardiography was done before bypass, but a patent foramen ovale was found in 3 patients when transesophageal echocardiography was performed after left ventricular assist device was activated. Patent foramen ovale was confirmed by inspection in all three patients and surgically closed during the same procedure. There were no patent foramen ovale closure-related complications.

Patient selection for assist devices: bridge to transplant

Patients in severely progressed states of heart failure can be bridged to successful heart transplantation with mechanical assist devices. Experience has demonstrated that patient selection and timing of device implantation are crucial for obtaining acceptable results when using this expensive technology. The degree of irreversible secondary organ dysfunction before re-establishing adequate cardiac output determines the chance of reaching transplantation. Patients who recover during support from all sequelae of end stage heart failure have an excellent outcome after heart transplantation.

Right hemidiaphragmatic elevation with a right-to-left interatrial shunt through a patent foramen ovale: a case report and literature review

A right-to-left shunt (RLS) is an uncommon complication of a patent foramen ovale (PFO) that may cause hypoxemia from venous admixture and ischemic complications from paradoxic embolization. This report presents the third described patient whose RLS through a PFO and profound hypoxemia developed in association with right hemidiaphragm dysfunction (but without a pressure gradient driving the right-to-left flow). In addition to extending the available experience with this unusual clinical event, we report on the successful closure of the PFO by a catheter-deployed double-umbrella device, after the positioning of which the patient's oxygenation normalized.

Pharmacologic exposure of an occult atrial septal defect

OBJECTIVE

To describe the diagnostic technique used to identify the presence of a symptomatic interatrial shunt obscured by normal intracardiac pressures and to discuss the unusual findings in this case and their relevance to the investigation of patients with unexplained hypoxemia.

DESIGN

Case report.

SETTING

Intensive care unit of a university teaching hospital.

PATIENT

A patient with a variant of the platypnea-orthodeoxia syndrome.

INTERVENTIONS

Intravenous administration of metaraminol.

MEASUREMENTS AND MAIN RESULTS

Clinical examination and routine investigations ruled out pneumonia or myocardial infarction as a cause of respiratory failure, and pulmonary angiography was normal other than for the demonstration of an interatrial communication. Repeated transthoracic echocardiograms failed to indicate the presence of a significant interatrial shunt that was eventually detected following temporary shunt reversal with intravenous metaraminol and confirmation by bubble-contrast transesophageal echocardiography and right heart catheter studies.

CONCLUSIONS

Symptomatic right-to-left intracardiac shunt may occur in patients with normal intracardiac and pulmonary artery pressures. The presence of a significant shunt cannot be ruled out by transthoracic echocardiography without the use of bubble contrast.

Clinical utility of echocardiography in the management of implantable ventricular assist devices

BACKGROUND

The high mortality rate of congestive cardiac failure, the cost and complications of cardiac transplantation, and the waiting list mortality rate resulting from donor organ scarcity have encouraged the development of surgical techniques as bridges to transplantation or as long-term palliative therapy. Implantable left ventricular assist devices are now routinely used as such a bridge, and within the REMATCH Trial, as permanent palliative devices in nontransplant candidates. These are mechanical managements with myriad mechanical complications and pitfalls. Echocardiography has been extensively used in our institution to detect and diagnose previously documented and hitherto unencountered complications of these procedures.

METHODS AND RESULTS

The role of echocardiography in these procedures, including preoperative patient selection, intraoperative transesophageal echocardiography, and postoperative troubleshooting and late follow-up, is discussed. We describe our clinical echocardiographic approach, which has developed over 91 assist-device procedures. The relative frequency and clinical impact of specific anatomic, physiologic, hemodynamic, and mechanical features are described. New techniques such as the Doppler quantification of assist device inflow obstruction are illustrated, as are the device cannula position, the detection of device valve failure, and the parameters related to the remodeling procedure.

CONCLUSIONS

Echocardiography in heart failure surgery has proved to be an invaluable tool in the diagnosis and management of mechanical complications. The experience gained in our institution may serve as an aid to new surgical programs treating these critically ill patients.

Intermittent atrial level right-to-left shunt with temporary hypoxemia in a patient during support with a left ventricular assist device

We report a 56-year-old male patient developing hypoxemia after surgical replacement of infected valves of a left ventricular assist device (LVAD, Novacor) which had supported him during the previous 15 months. Contrast transesophageal echocardiography (TEE) revealed an atrial septal defect with intermittent right-to-left shunt across a patent foramen ovale. We postulate that the shunt detected in this patient occurred as a consequence of reduced pulmonary vascular compliance due to positive end-expiratory pressure (PEEP) and an increase of mean intrathoracic pressure. Furthermore, we hypothesize that synchronized LVAD operation exacerbates any potential right-to-left shunt due to the profound left ventricular unloading which occurs during LVAD support. In this first report of a right-to-left shunt from a previously unrecognized patent foramen ovale in a Novacor patient, the subsequent transient hypoxemia could be managed by avoiding PEEP of more than 3 mmHg, and mean airway pressure of more than 11 mmHg and by careful volume replacement in order to prevent the pump from completely emptying the left ventricle (LV) and the left atrium (LA). Thus, prior to every LVAD implantation a transesophageal contrast echocardiography with Valsalva maneuver should be performed to identify intracardiac right-to-left shunt.

Transcatheter closure of a patent foramen ovale following mitral valve replacement

We report the successful closure of a postoperative patent foramen ovale in a patient who underwent coronary artery bypass grafting and mitral valve replacement for severe mitral insufficiency. The postoperative course was complicated by severe hypoxemia due to a large patent foramen ovale. The patient underwent transcatheter closure with the Das Angel Wings transcatheter occluder (Microvena Corporation, White Bear Lake, MN) with immediate improvement.

Usefulness of Transesophageal Echocardiography in Diagnosing Valve Leakage of Left Ventricular Assist Device

In this case report, we present the utility of transesophageal echocardiography in the detection of two uncommon complications of left ventricular assist devices: regurgitation of the bioprosthetic valve in the inflow conduit and a tear of a Dacron conduit with hematoma formation and compression of the right ventricular free wall.