Monitoring persistent pulmonary hypertension of the newborn using the arterial to end tidal carbon dioxide gradient

Persistent pulmonary hypertension of the newborn (PPHN) can be monitored theoretically by the difference of the partial pressure of arterial (PaCO2) to end-tidal CO2 (EtCO2). We aimed to test the hypothesis that the PaCO2-EtCO2 gradient in infants with PPHN would be higher compared to infants without PPHN. Prospective, observational study of term-born ventilated infants with echocardiographically-confirmed PPHN with right-to-left shunting and term-born control infants without respiratory disease. The PaCO2-EtCO2 gradient was calculated as the difference between the PaCO2 measured from indwelling arterial sample lines and EtCO2 measured by continuous Microstream sidestream capnography. Twenty infants (9 with PPHN and 11 controls) were studied with a median (IQR) gestational age of 39.5 (38.7-40.4) weeks, a birthweight of 3.56 (3.15-3.93) kg and a birthweight z-score of 0.03 (- 0.91 to 1.08). The PaCO2-EtCO2 gradient was larger in the infants with PPHN compared to those without PPHN after adjusting for differences in the mean airway pressure and fraction of inspired oxygen (adjusted p = 0.037). In the infants with PPHN the median PaCO2-EtCO2 gradient decreased from 10.7 mmHg during the acute illness to 3.3 mmHg pre-extubation. The median difference in the gradient was significantly higher in infants with PPHN (6.2 mmHg) compared to infants without PPHN (-3.2 mmHg, p = 0.022). The PaCO2-EtCO2 gradient was higher in infants with PPHN compared to term born infants without PPHN and decreased over the first week of life in infants with PPHN. The gradient might be utilised to monitor the evolution and resolution of PPHN.

Severe hypoxemia after radiofrequency ablation for atrial fibrillation in palliatively repaired tetralogy of Fallot: A case report

BACKGROUND

Patients with tetralogy of Fallot (TOF) often have arrhythmias, commonly being atrial fibrillation (AF). Radiofrequency ablation is an effective treatment for AF and does not usually cause severe postoperative hypoxemia, but the risk of complications may increase in patients with conditions such as TOF.

CASE SUMMARY

We report a young male patient with a history of TOF repair who developed severe hypoxemia after radiofrequency ablation for AF and was ultimately confirmed to have a new right-to-left shunt. The patient subsequently underwent atrial septal occlusion and eventually recovered.

CONCLUSION

Radiofrequency ablation may cause iatrogenic atrial septal injury; thus possible complications should be predicted in order to ensure successful treatment and patient safety.

The prevalence of positive right to left shunt in migraine patients with and without aura: A new single-center study in China

BACKGROUND

Recently, many studies have reported that there may be association between positive right-to-left shunt (RLS) and migraine, especially Migraine with aura (MA) patients. However, these researches are mostly limited in Western country. And the latest study describing the prevalence of RLS in Chinese patients with migraine was conducted five years ago. It indicated the significant higher rate of positive RLS in MA patients than migraine without aura(MWOA) group. However, no consistent results were observed according to our daily work.

OBJECTIVE

To investigate the prevalence and grade of RLS in migraine patients with and without aura and to evaluate the potential association between positive RLS and migraine with aura.

METHODS

A total of 91 migraine patients were involved, including 57 MWOA patients and 34 MA patients. MWOA and MA were diagnosed according to the International Classification of Headache Disorders, 3rd edition (beta version) (ICHD-3). Contrast transcranial Doppler ultra-sound (cTCD) was used to assess the prevalence of positive RLS, the associations between RLS and presence of aura.

RESULTS

The overall prevalence of RLS in migraine patients was 35.2%. In MA group, 44.1% (15/34) were positive for RLS overall, higher than MWOA group (29.8%,17/57). However, the differences were not significant (P = 0.167). And there were no marked differences in the prevalence of large, middle and small shunt between MA and MWOA patients.

CONCLUSION

Our study suggested MA patients have the slightly higher prevalence of positive RLS than MWOA patients in China. However, there were no significant differences, which was different from the previous studies. Our findings suggested the negative association between the positive RLS and migraine with aura.

Pulmonary arteriovenous malformation and a concurrent patent ductus arteriosus in a Doberman

A 7-week-old male Doberman presented with tachypnea, dyspnea and a VI/VI, left cranial, continuous heart murmur. Thoracic radiographs revealed severe left-sided cardiomegaly, presence of a rounded soft tissue opacity in the caudodorsal aspect of the thoracic cavity and signs of left-sided congestive heart failure. Clinical signs of heart failure were medically controlled. Echocardiography and computed tomography demonstrated a left-to-right shunting patent ductus arteriosus (PDA) in combination with a right-to-left shunting pulmonary arteriovenous malformation (PAVM) between the right main pulmonary artery and the right caudal pulmonary vein. Arterial blood gasses revealed mild hypoxemia. Transcatheter occlusion of the PDA using an Amplatz Canine Duct Occluder was performed. Four months post-operatively, echocardiography showed normal cardiac size and function with complete PDA closure. Thoracic radiographs revealed absence of the rounded opacity and resolution of cardiomegaly and vascular congestion. The PAVM was no longer visualized on repeated computed tomography and the arterial blood gasses were within normal limits. A PAVM connecting a pulmonary artery to a pulmonary vein has only rarely been reported in dogs. This report describes the presence of a congenital PAVM in combination with a PDA in a dog, which has not been previously reported in veterinary medicine.

Contrast-enhanced transcranial doppler versus contrast transthoracic echocardiography for right-to-left shunt diagnosis

RLS can be diagnosed using US, CT angiography, and right heart catheterization. However, most reliable diagnostic modality remains undetermined. c-TCD was more sensitive than c-TTE in the diagnosis of RLS. This was true especially for the detection of provoked shunts or mild shunts. c-TCD can be used as the preferred screening method for RLS.

Atypical distally distributed cutis marmorata decompression sickness associated with unconventional use of thermal protection in a diver with persistent foramen ovale

Cutis marmorata is a mottled, marbling, livedoid rash caused by vascular inflammation and congestion in cutaneous decompression sickness. It may occur during or after ascent due to the formation of bubbles from dissolved nitrogen accumulated throughout the dive. It is strongly associated with the presence of right to left shunts, particularly persistent (patent) foramen ovale (PFO). We report a case of cutis marmorata decompression sickness of an unusual pattern associated with unconventional use of thermal protection (a 'shorty' wetsuit worn over full suit) by a diver with a PFO. The patient also had neurological manifestations of decompression sickness. The distal lower limb pattern of involvement favours the hypothesis that cutis marmorata in humans is likely to be due to bubbles in the skin itself and/or adjacent tissues rather than cerebrally mediated.

A retrospective review of divers treated for inner ear decompression sickness at Fiona Stanley Hospital hyperbaric medicine unit 2014-2020

Introduction

Inner ear decompression sickness (IEDCS) is increasingly recognised in recreational diving, with the inner ear particularly vulnerable to decompression sickness in divers with a right-to-left shunt, such as is possible through a persistent (patent) foramen ovale (PFO). A review of patients treated for IEDCS at Fiona Stanley Hospital Hyperbaric Medicine Unit (FSH HMU) in Western Australia was performed to examine the epidemiology, risk factors for developing this condition, the treatment administered and the outcomes of this patient population.

Methods

A retrospective review of all divers treated for IEDCS from the opening of the FSH HMU on 17 November 2014 to 31 December 2020 was performed. Patients were included if presenting with vestibular or cochlear dysfunction within 24 hours of surfacing from a dive, and excluded if demonstrating features of inner ear barotrauma.

Results

There were a total of 23 IEDCS patients and 24 cases of IEDCS included for analysis, with 88% experiencing vestibular manifestations and 38% cochlear. Median dive time was 40 minutes and median maximum depth was 24.5 metres. The median time from surfacing to hyperbaric oxygen treatment (HBOT) was 22 hours. Vestibulocochlear symptoms fully resolved in 67% and complete symptom recovery was achieved in 58%. A PFO was found in 6 of 10 patients who subsequently underwent investigation with bubble contrast echocardiography upon follow-up.

Conclusions

IEDCS occurred predominantly after non-technical repetitive air dives and ongoing symptoms and signs were often observed after HBOT. Appropriate follow-up is required given the high prevalence of PFO in these patients.

Myocardial Enhancement Following Agitated Saline Contrast Study in a Boxer Dog

•Myocardial enhancement after agitated saline contrast study in a dog is described. •Suspect air microemboli can inadvertently be introduced into coronary vasculature. •Air microemboli are a theoretic risk of saline contrast echocardiography.

Effective long-term sirolimus treatment in hypoxemia mainly due to intrapulmonary right-to-left shunt in a patient with multiple vascular anomalies

Pulmonary arteriovenous malformations (PAVMs), particularly where feeding artery/arteries to PAVMs ≥ 3 mm can be treated with embolization. The treatment for hypoxemia resulting from multiple small or diffuse PAVMs remains unclear.We report a girl aged 5 years and 10 months presented with cyanosis and decreased activity after exercise (83-85% of pulse oxygen saturation, SpO₂). She had 1 skin lesion on her face and 1 suspected hemangioma on her left upper extremity at birth and that gradually disappeared spontaneously. Physical examination revealed clubbed fingers, and abundant vascular networks on her back. Contrast-enhanced lung CT (slice thickness:1.25 mm) with vascular three-dimensional reconstruction and abdominal CT revealed increased bronchovascular bundles, increased diameter of the pulmonary artery and ascending aorta, and intrahepatic portosystemic venous shunts due to patent ductus venosus. Echocardiography revealed increased diameter of aortic and pulmonary artery. Transthoracic contrast echocardiography was highly positive (bubble appearing in the left ventricle after 5 cardiac cycles). Abdominal doppler ultrasound revealed hepatic-portal venous shunt. Magnetic resonance imaging, artery and vein of the brain revealed multiple malformations of venous sinuses. The patient received sirolimus for 2 years and 4 months. Her condition improved significantly. SpO₂ gradually increased to 98%. Her finger clubbing gradually normalized.Our report implicates sirolimus might be a potential treatment option in persistent hypoxemia mainly due to intrapulmonary right-to-left shunt even small multiple or diffusive PAVMs in pediatric patients with multiple cutaneous and visceral vascular anomalies.

Acute hypoxemia due to right-to-left shunt via a patent foramen ovale during left internal thoracic artery to left anterior descending artery anastomosis in off-pump coronary artery bypass grafting: a case report

BACKGROUND

A right-to-left shunt via a patent foramen ovale (PFO) during off-pump coronary artery bypass (OPCAB) may result in difficulties in oxygenation and circulatory management. We herein present a case of a marked shunt via a PFO during OPCAB.

CASE PRESENTATION

A 74-year-old man who had aortic root enlargement, compressing the right atrium, and an atrial septal aneurysm, underwent OPCAB. When the heart was fixed for the anastomosis of the left anterior descending artery, sudden hypoxemia and hypotension were observed. Intraoperative transesophageal echocardiography (TEE) showed a right-to-left shunt via a PFO that was unnoticed preoperatively. After the anastomosis was completed, TEE revealed no shunt through the PFO.

CONCLUSIONS

We should check for a PFO in case of an atrial septal aneurysm. Compression of the right atrium is considered an important anatomical risk of the right-to-left shunt in OPCAB.

Coronary Flow Assessment in an Adult with Anomalous Left Coronary Arising from the Pulmonary Artery

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ALCAPA can be diagnosed for the first time in older adults.

•

Collateral coronary blood flow from the RCA leads to RCA dilatation.

•

Consider ALCAPA with reduced LVEF, bright papillary muscles, MR, and RCA dilatation.

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Color and spectral Doppler is useful to assess perioperative coronary arterial flow.

Long term central venous catheters for haemodialysis causing an extra-cardiac right-to-left shunt

Central venous catheters can provide long-term access for haemodialysis patients who cannot have an arteriovenous fistula or graft fashioned. However, long-term central venous catheter use for haemodialysis may lead to complications including central venous stenosis, and superior vena cava obstruction in its worst form. Here, we describe the case of a patient on haemodialysis via central venous catheters for over 20 years, in whom chronic superior vena cava obstruction led to the development of mediastinal collateral vessels. These drained deoxygenated systemic venous blood into the oxygenated pulmonary venous system. Over time, this caused a significant right-to-left shunt and resulting hypoxaemia. This is the first reported case of central venous catheters used for haemodialysis resulting in an acquired, extra-cardiac, right-to-left shunt.

Hypoxemia found after hospitalization with right hemiplegia due to cerebral infarction: platypnea-orthodeoxia syndrome in the older people

An 89-year-old woman was admitted to our hospital for subacute onset of right upper and lower limb weakness and was diagnosed with acute cerebral infarction. During rehabilitation, close observation revealed that her oxygen saturation decreased in the sitting position and improved in the recumbent position without any subjective symptoms of dyspnea. Transthoracic and transesophageal echocardiography and cardiac catheterization revealed a large patent foramen ovale with an atrial septal aneurysm with right-to-left shunting through the defect, and she was diagnosed with platypnea-orthodeoxia syndrome. Her right hemiplegia caused the trunk to collapse, so the patient slumped when in sitting position, and the trunk tilted to the right forward, resulting in an increased right-to-left shunt. Her peripheral capillary oxygen saturation improved in the upright sitting position supported by therapists. This case suggests that right hemiplegia may exacerbate the symptoms of platypnea-orthodeoxia syndrome. <Learning objective: Platypnea-orthodoxia syndrome (POS) is a rare disease and often not clearly diagnosed. Previous studies have reported POS due to patent foramen ovale (PFO) after the onset of subclinical cerebral infarction. To our knowledge, this is the first case to suggest that trunk collapse during sitting due to right hemiplegia exacerbated the hypoxemia caused by POS. Moreover, 20-30% of adults may have asymptomatic PFO. POS may be detected by examining changes in oxygen saturation in different postures.>.

Evaluation of right-to-left shunt on contrast-enhanced transcranial Doppler in patent foramen ovale-related cryptogenic stroke: Research based on imaging

BACKGROUND

Cardiogenic embolism caused by patent foramen ovale (PFO) is a common etiology of cryptogenic stroke (CS), particularly in young and middle-aged patients. Studies about right-to-left shunt (RLS) detection using contrast-enhanced transcranial Doppler (c-TCD) are numerous. According to the time phase and number of microbubbles detected on c-TCD, RLS can be classified and graded. We hypothesized that the characteristics of an infarction lesion on diffusion-weighted imaging differs when combining the type and grade of RLS on c-TCD in patients with PFO-related CS.

AIM

To explore the characteristics of infarction lesions on diffusion-weighted imaging when combining the RLS type and grade determined by c-TCD.

METHODS

We retrospectively evaluated CS patients from August 2015 to December 2019 at a tertiary hospital. In total, 111 PFO-related CS patients were divided according to whether RLS was permanent (microbubbles detected both at resting state and after the Valsalva maneuver) or latent (microbubbles detected only after the Valsalva maneuver) on c-TCD. Each group was subdivided into small, mild and large RLS according to the grade of shunt on c-TCD. A normal control group was composed of 33 patients who suffered from simple dizziness. Intragroup and intergroup differences were analyzed in terms of clinical, laboratory and diffusion-weighted imaging lesion characteristics. The correlation between RLS grade evaluated by c-TCD and size of PFO determined by transesophageal echocardiography were also analyzed.

RESULTS

In 111 patients with PFO-related CS, 68 had permanent RLS and 43 had latent RLS. Clinical characteristics and laboratory tests were not significantly different among the permanent RLS, latent RLS and normal control groups. The proportion of patients with multiple territory lesions in the permanent RLS group (50%) was larger than that in the latent RLS group (27.91%; P = 0.021). Posterior circulation was more likely to be affected in the latent RLS group than in the permanent RLS group (30.23% vs 8.82%, P = 0.004). Permanent-large and latent-large RLS were both more likely to be related to multiple (P_trend = 0.017 and 0.009, respectively), small (P_trend = 0.035 and 0.006, respectively) and cortical (P_trend = 0.031 and 0.033, respectively) lesions. The grade of RLS evaluated by c-TCD was correlated to the size of PFO determined by transesophageal echocardiography (r = 0.758, P < 0.001).

CONCLUSION

Distribution of the infarct suggested the possible type of RLS. Multiple, small and cortical infarcts suggest large RLS induced by a large PFO.

Importance of saline contrast transthoracic echocardiography for evaluating large right-to-left shunt in patent foramen ovale associated with cryptogenic stroke

Transcatheter closure of patent foramen ovale (PFO) is an effective therapy for preventing recurrent stroke in very specific patient cohorts, such as cryptogenic stroke (CS). The identification of high-risk PFO, which is more likely to be linked to CS, is essential. This study aimed to assess the accuracy of saline contrast transthoracic echocardiography (TTE) for evaluating large right-to-left (RL) shunt. We enrolled 119 patients with or without CS who were confirmed to have PFO by transesophageal echocardiography (TEE) or catheterization. The severity of RL shunt evaluated by TTE and TEE was classified as follows: small (< 10 microbubbles), moderate (10–20 microbubbles), and large (> 20 microbubbles). With TTE, large RL shunt was observed in 94 (79%) of 119 patients, including 66 of 74 with CS and 28 of 45 without CS. With TEE, large RL shunt was observed in 33 (28 %) patients, including 26 with CS and 7 without CS. TTE showed large RL shunt more frequently than TEE (p < 0.01). Large RL shunt evaluated by TTE had a sensitivity of 89 % and an accuracy of 70 % for the association with CS, whereas large RL shunt evaluated by TEE had a sensitivity of 35% and an accuracy of 56 %. Accuracy was significantly greater in TTE than in TEE (p = 0.02). In conclusion, TTE identified large RL shunt associated with CS with higher sensitivity and accuracy compared to TEE. Our findings suggest that the decision for device closure should be made based on the severity of RL shunt by TTE.

Cryptogenic Stroke Caused by Pulmonary Arterial Venous Malformation with Massive Right-to-Left Shunt: A Case Report

Background

Pulmonary arterial venous malformation (PAVM) is an abnormal vascular malformation between pulmonary arteries and veins characterized by varying degrees of right-to-left shunts (RLS). Cryptogenic stroke (CS) due to paradoxical embolism (PE) caused by PAVM is relatively rare in the clinic.

Case Presentation

We report the case of a 54-year-old right-handed woman who presented with sudden-onset left-sided limb weakness for 2 h. A physical examination revealed normal vital signs but weakness in her left upper and lower limbs, graded as 1/5 using the Medical Research Council scale. Her National Institutes of Health Stroke Scale (NIHSS) score was 8, and her modified Rankin scale (mRS) was 4. Brain diffusion-weighted imaging showed acute infarction in the right basal ganglia and the radiation crown but brain magnetic resonance angiography found no obvious abnormality. A transcranial Doppler ultrasound with bubble study (TCD-b) found the rain curtain sign of microbubbles in the left middle cerebral artery, reflecting significant RLS. Transesophageal echocardiography (TEE) and transthoracic echocardiography (TTE) were conducted to distinguish between intra- and extracardiac shunts. A pulmonary computerized tomography angiogram (CTA) demonstrated a PAVM. We considered the patient had CS due to PE caused by PAVM. Thrombolytic therapy within the time window was performed. Then, transcatheter device occlusion of the arteriovenous fistula was successfully undertaken, and the patient carried on with rehabilitation training. At a 15-month follow-up, there were no catheter-related complications or recurrent stroke, and her NIHSS and mRS scores were both 0.

Conclusions

PAVM is an important risk factor for PE and CS and should not be ignored as a possible etiology in stroke patients without any other risk factors. CTA of the pulmonary artery is the recommended gold standard for diagnosing and locating a PAVM. Thrombolytic therapy within the time window combined with transcatheter device occlusion of arteriovenous malformation and rehabilitation training may benefit the recovery of patients with CS caused by PE resulting from PAVM.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40120-021-00275-y.

Large eustachian valve fostering paradoxical thromboembolism: passive bystander or serial partner in crime?

Catheter-based closure of patent foramen ovale (PFO) is more effective than medical therapy in the prevention of recurrent stroke[1]. It is likely that a proportion of patients evaluated for potential transcatheter PFO closure has actually different anatomical variants particularly common in the right atrium such as eustachian valve, Chiari network, Thebesian valve and Crista Terminalis. Notably, the eustachian valve may represent an increased risk factor for left circulation thromboembolism beyond that associated with PFO size and shunting. Such patients may benefit the most from percutaneous closure procedure.

Comparison of clinical and biological differences between patent foramen ovale subtypes in ischemic stroke

BACKGROUNDS

The patent foramen ovale (PFO) is an atrial septal tunnel with a flap-like opening, causing a right-to-left shunt (RLS) between the atrial chambers. There are few studies on ischemic stroke characteristics based on PFO subtypes. In this study, we investigated whether there are differences in clinical characteristics, RLS amount, and the etiology of stroke defined by the Trial of ORG 10,172 in Acute Stroke Treatment (TOAST) classification between PFO subtypes.

METHODS

We retrospectively analyzed consecutive ischemic stroke patients with PFO who were admitted to the Jeonbuk National University Hospital from November 2013 to February 2015, and performed a microbubble test to detect RLS. The patients were divided into two groups according to RLS characteristics: constant RLS group and provoked RLS group. We compared the clinical characteristics and degree of RLS between the PFO subtypes.

RESULTS

Out of 144 ischemic patients evaluated in this study, 83 (58%) were classified into the constant RLS group and 61 (42%) into the provoked RLS group. The proportion of microembolic signal (MES) grades 3 and 4 was significantly higher in the constant RLS group than in the provoked RLS group. There were no statistical differences in the distribution of TOAST classification between the two groups.

CONCLUSION

The constant RLS group showed a higher proportion of high-grade MES than the provoked RLS group.

Echocardiography - techniques and pitfalls whilst diagnosing persistent (patent) foramen ovale as a risk factor in divers with a history of decompression sickness

The case of a diver with a history of decompression sickness (DCS) after recreational scuba diving is presented. Cutis marmorata, a subtype of cutaneous DCS, has been consistently associated with the presence of a persistent (patent) foramen ovale (PFO) as a risk factor. Diagnostic uncertainty arose when transthoracic echocardiography with antecubital injection of agitated saline bubbles (ASBs) did not show any significant shunt, but the presence of a large Eustachian valve was counteracted by intra-femoral injection of ASBs, showing a large PFO with spontaneous shunting. The importance of proper echocardiography techniques prior to resorting to intra-femoral injection of ASBs to counteract the haemodynamic effects of the Eustachian valve is emphasised.

Does persistent (patent) foramen ovale closure reduce the risk of recurrent decompression sickness in scuba divers?

INTRODUCTION

Interatrial communication is associated with an increased risk of decompression sickness (DCS) in scuba diving. It has been proposed that there would be a decreased risk of DCS after closure of the interatrial communication, i.e., persistent (patent) foramen ovale (PFO). However, the clinical evidence supporting this is limited.

METHODS

Medical records were reviewed to identify Swedish scuba divers with a history of DCS and catheter closure of an interatrial communication. Thereafter, phone interviews were conducted with questions regarding diving and DCS. All Swedish divers who had had catheter-based PFO-closure because of DCS were followed up, assessing post-closure diving habits and recurrent DCS.

RESULTS

Nine divers, all with a PFO, were included. Eight were diving post-closure. These divers had performed 6,835 dives (median 410, range 140-2,200) before closure, and 4,708 dives (median 413, range 11-2,000) after closure. Seven cases with mild and 10 with serious DCS symptoms were reported before the PFO closure. One diver with a small residual shunt suffered serious DCS post-closure; however, that dive was performed with a provocative diving profile.

CONCLUSION

Divers with PFO and DCS continue to dive after PFO closure and this seems to be fairly safe. Our study suggests a conservative diving profile when there is a residual shunt after PFO closure, to prevent recurrent DCS events.

Tumor Embolism Through Right-to-Left Shunt Due to Venous Invasion of Esophageal Carcinoma

A 69-year-old man was admitted to the hospital with right hemiparesis and global aphasia. Perfusion computed tomography imaging revealed ischemic penumbra in the middle cerebral artery territory. Angiography showed left middle cerebral artery occlusion. Mechanical thrombectomy with one pass was performed, and successful recanalization was obtained. Embolic material was retrieved; it contained tumor fragments with atypical keratinizing squamous cell carcinoma. Contrast computed tomography imaging indicated tumor invasion into the superior vena cava, and contrast transcranial Doppler indicated the presence of a right-to-left shunt after the Valsalva maneuver. We diagnosed the patient with acute ischemic stroke of large vessel occlusion due to venous invasion of esophageal carcinoma via a right-to-left shunt. To the best of our knowledge, this is the first case of embolic occlusion resulting from an extracardiac tumor via a right-to-left shunt. Contrast transcranial Doppler potentially detects right-to-left shunts in patients who cannot undergo transesophageal echocardiography.

Complete Superior and Inferior Vena Cava Obstruction Associated with Systemic-to-Pulmonary Venous Shunts in a Young Female with Heterozygous Prothrombin G20210A Gene Mutation

Complete superior vena cava (SVC) and inferior vena cava (IVC) obstruction is not uncommon and most commonly associated with malignancy. The risk increases in patients with central lines and hypercoagulable states such as with malignancy, thrombophilia, or use of oral contraceptive pills. According to our knowledge, complete SVC and IVC obstruction associated with systemic-to-pulmonary venous shunts in patients with prothrombin G20210A gene mutation has not been reported in the literature. Here we report the case of a 34-year-old female with complete SVC and IVC obstruction presenting with oxygen desaturation and shortness of breath due to systemic-to-pulmonary venous shunts. The unusual collateral pathway was secondary to SVC obstruction. The patient was managed conservatively, and she remained stable.

The Connection Between Patent Foramen Ovale and Migraine

"Observational studies have identified a relationship between patent foramen ovale (PFO) and migraine headache. In people who have migraine with aura, 40% to 60% have a PFO, compared with 20% to 30% in the general adult population. It is hypothesized that migraine, especially migraine with aura, may be triggered by hypoxemia or vasoactive chemicals (eg, serotonin), which are ordinarily metabolized during passage through the lungs. Although PFO closure is currently not a FDA-approved therapy for migraines, randomized trials suggest that this intervention may benefit a subgroup of migraineurs."

SCORE risk scale as a prognostic factor after sudden sensorineural hearing loss

Menezes et al. recently published an interesting study on cardiovascular prognostic factors for sudden sensorineural hearing loss (SSNHL), analyzing therapeutic strategies with intravenous and intratympanic corticosteroids and evaluating the application of the Systematic Coronary Risk Evaluation risk scale to classify risk in patients with SSNHL. In addition to intravenous and intratympanic corticosteroids, we would like to stress the role of hyperbaric oxygen therapy (HBOT). The new guidelines on SSNHL and the most recent scientific evidence emphasize the therapeutic role of HBOT. In a previous study, we recommended the use of HBOT in addition to intravenous steroid for patients with idiopathic SSNHL. For the best outcomes, we also recommended starting treatment within 14 days from the onset of SSNHL. In the same article, we discussed potential risk factors for SSNHL. Among cardiovascular risk factors, we suggest the possible association between patent foramen ovale (PFO) and SSNHL. The higher prevalence of PFO in our patients (50%) compared to controls suggests that SSNHL may be attributable to a paradoxical embolism, such as a venous embolism as a result of PFO.

Right-to-Left Shunt and the Clinical Features of Migraine with Aura: Earlier but Not More

BACKGROUND

The causal relationship between patent foramen ovale (PFO) and migraine with aura (MA) is controversial. We aimed at exploring whether attack clinical features relate to the presence of right-to-left shunt (RLS) in MA patients.

METHODS

We retrospectively examined a cohort of consecutive patients diagnosed with MA in our headache center and undergoing transcranial doppler (TCD) for RLS detection. We collected from our clinical electronic dossiers, clinical features of MA attacks (type, frequency, duration of aura phenomenon, trigger factors, onset age), family history for MA, thrombophilia genotypes, and the response to preventive treatments. RLS was stratified for severity according to the results of the TCD examination.

RESULTS

We found 111 patients. Binary logistic regression analysis showed that among features of MA attacks, only onset age was associated with the presence of RLS (p < 0.0001). Patients with RLS presented the first MA attack at a younger age (p < 0.0001). The greater RLS severity, the younger was onset age (p < 0.00001) and the presence of atrial septal aneurysms (ASA) was associated with a further decrease in onset age (ρ = -539, p < 0.00001). Family history for MA was associated with the presence of RLS (chi-square p = 0.022). Response to preventive treatments was not influenced by the type of treatment (antiplatelet compared with no antiplatelet drugs), comorbidity with migraine without aura, RLS presence, or by their double interactions (Logistic regression, consistently p > 0.05).

CONCLUSION

Our findings support the hypothesis that although PFO does not influence MA attack frequency, it is not merely a bystander in MA physiopathology, as RLS, its severity, and the presence of ASA possibly make a difference in the disease history.

Risk mitigation in divers with persistent (patent) foramen ovale

In this issue, Anderson and colleagues report follow-up of divers who were found to have a persistent (patent) foramen ovale (PFO) or, in eleven cases, an atrial septal defect (ASD). In most divers diagnosis followed an episode of decompression illness (DCI). The efficacy of closure of the PFO/ASD in preventing future DCI was compared with conservative diving. They reported that in the closure group the occurrence of confirmed DCI decreased significantly compared with pre-closure, but in the conservative group this reduction was not significant.

It is believed there are three requirements for a diver to suffer shunt-mediated DCI: A significant right-to-left shunt (usually a large PFO but sometimes an ASD or pulmonary arteriovenous malformation). Venous bubbles nucleated during decompression circumvent the lung filter by passing through the shunt. Target tissues are supersaturated with dissolved inert gas, so that they are able to amplify embolic bubbles. All three are required because DCI does not occur after contrast echocardiography when bubbles cross a right-to-left shunt.

Therefore, there are two ways that a diver who has suffered shunt-mediated DCI may continue to dive - either their shunt is sealed or future dives should be so conservative that venous bubbles are not liberated and/or critical tissues are not able to amplify embolic bubbles.

PFO/ASD closure will give divers a risk of DCI comparable to the risk in others without a right-to-left shunt, if the procedure adequately seals the shunt. Closure of the shunt will not prevent a diver suffering DCI by other mechanisms, such as when there is arterial gas embolism (AGE) as a result of pulmonary barotrauma or when the dive profile is provocative (e.g., if there is rapid ascent or missed decompression stops). Conservative diving will be effective only if all the dives performed are truly conservative and prevent bubble nucleation and/or amplification.

The study by Anderson et al. has a number of serious limitations. The study was small with only 62 self-selected divers, who self-reported outcomes. Eleven divers had not had DCI when their PFO or ASD was detected. Initially 36 divers were classified as closure and 26 as conservative treatment, but six subjects crossed from the conservative group to the closure group. Three of the six dived in the conservative group before having closure and are classified in both groups depending on whether the dives performed were before or after closure. As a result, there were 42 in the closure group and 23 in the conservative group.

Randomisation to the treatment groups was not possible and its absence results in imbalance. Because the closure group is approximately twice as large as the conservative group, similar changes in incidence would have a greater probability of achieving statistical significance in the former. Large shunts were present in more than three-quarters of the closure group but fewer than half of the conservative group. The authors have three definitions of a 'large' PFO, so the definition of large was inconsistent. All ASDs were considered to be large.

When dealing with small numbers, one needs patient-level data, but that is lacking and may mask inconsistency in management. The divers were investigated and treated in at least 38 hospitals (some divers did not state where they were treated). We do not know what devices were used for PFO/ASD closure, and closure effectiveness varies, or what tests were performed to assess the effectiveness of closure.

The primary end-point was not different between the two groups because only two episodes of confirmed DCI occurred in each group. The authors also considered a softer and subjective end-point, possible DCI.

Crucially we are not told what the divers in the conservative group were told constitutes a conservative dive and whether it was consistent. Nor are we told whether they followed the advice given. That is important because it appears that incidence of possible DCI increased considerably in only the conservative group, which means either that the advice they were given on what constitutes a conservative dive was flawed, that the divers failed to follow good advice or that they frequently reported innocent symptoms as possible DCI, because knowledge that they had a PFO may have increased their reporting - introducing further bias.

There should be assessment of whether DCI after the intervention was shunt-mediated or had another cause. For that assessment, one needs to know details of the dives resulting in symptoms, clinical manifestations and latency of onset.

I have investigated 20 divers who had DCI after PFO closure. In five divers, a contrast echocardiogram showed a significant residual shunt. Typically, the diver had their closure procedure by a cardiologist lacking knowledge of diving medicine and no post-closure contrast echocardiogram was performed. In one case, the diver's PFO was closed but they had a residual pulmonary shunt that was not detected. In those cases where there is a significant residual shunt, the dive profiles, clinical manifestations and latencies of onset were typical of shunt-mediated DCI.

Three divers, who had PFO closure with no residual shunt, subsequently had neurological symptoms with manifestations consistent with AGE secondary to pulmonary barotrauma. High resolution CT scans of their chests showed pulmonary bullae and emphysema.

The remaining divers seen had no residual shunt but had performed highly provocative dives, usually much deeper than 50 metres' sea water (msw). The most recent case that I saw had dived to 102 metres' fresh water (mfw) in a lake at high altitude breathing trimix.

In contrast, several hundred divers in whom I diagnosed a PFO and who elected to dive conservatively had not reported further DCI. I advised them that I have never seen shunt-mediated DCI after dives breathing air to depths of 15 msw or less provided no rules were broken. So I set that as the depth limit or allow them to dive to greater depths breathing nitrox so that there are equivalent partial pressures of nitrogen (e.g., 19 msw with nitrox 32 or 23 msw with nitrox 40) provided they use an air decompression table/algorithm. Alternatively, one can dive using the DCIEM recreational air diving table.

Recurrence of DCI after PFO closure may be the result of a residual shunt or may have other causes. It is difficult to draw conclusions about the safety of 'conservative' diving unless one knows what the divers were advised constitutes conservative dives and whether they adhered to the advice.

The effectiveness of risk mitigation interventions in divers with persistent (patent) foramen ovale

INTRODUCTION

Persistent (patent) foramen ovale (PFO) is a recognized risk for decompression sickness (DCS) in divers, which may be mitigated by conservative diving or by PFO closure. Our study aimed to compare the effectiveness of these two risk mitigation interventions.

METHODS

This was a prospective study on divers who tested positive for PFO or an atrial septal defect (ASD) and either decided to continue diving without closure ('conservative group'), or to close their PFO/ASD and continue diving ('closure group'). Divers' characteristics, medical history, history of diving and history of DCS were reported at enrollment and annually after that. The outcome measures were the incidence rate of DCS, frequency and intensity of diving activities, and adverse events of closure.

RESULTS

Divers in both groups dived less and had a lower incidence rate of confirmed DCS than before the intervention. In the closure group (n = 42) the incidence rate of confirmed DCS decreased significantly. Divers with a large PFO experienced the greatest reduction in total DCS. In the conservative group (n = 23), the post-intervention decrease in confirmed DCS incidence rate was not significant. Of note, not all divers returned to diving after closure. Seven subjects reported mild adverse events associated with closure; one subject reported a serious adverse event.

CONCLUSIONS

PFO closure should be considered on an individual basis. In particular, individuals who are healthy, have a significant DCS burden, a large PFO or seek to pursue advanced diving may benefit from closure.

Characteristics and analysis of right-to-left shunt-related dizziness in patients without hypoxemia

Objective

This study aimed to analyze right-to-left shunt-related dizziness in three patients without hypoxemia.

Methods

Case 1 was a 47-year-old man with a history of cerebral infarction 8 years previously and recurrent dizziness for > 6 months. Patent foramen ovale (PFO) was found with a severe right-to-left shunt. Case 2 was a 50-year-old man with acute stroke. He had a history of repeated dizziness for > 4 years. He was diagnosed with PFO with a severe right-to-left shunt after admission. Case 3 was a 73-year-old woman with recurrent dizziness for > 10 months. Pulmonary arteriovenous fistula was diagnosed upon admission. No patients had hypoxemia.

Results

After percutaneous PFO occlusion in Cases 1 and 2, the patients were followed up for 6 months and 1 year, respectively. Two patients had relief of dizziness without recurrence. In Case 3, the pallor improved and the dizziness was relieved after pulmonary arteriovenous fistula embolization and did not recur over a 6-month follow-up.

Conclusions

There was a possible association between a severe right-to-left shunt and dizziness, although hypoxemia was absent in the cases. Intervention to eliminate a left-to-right shunt can improve dizziness in patients without hypoxemia with a severe right-to-left shunt.

Pediatric Acute Paradoxical Cerebral Embolism with Pulmonary Embolism Caused by Extremely Small Patent Foramen Ovale

Herein, we report a pediatric case of acute paradoxical cerebral embolism complicated by serious acute pulmonary embolism that was caused by an extremely small patent foramen ovale (PFO). The patient had no medical history suggestive of any other reason.

Paradoxical cerebral embolism may occur even with an extremely small PFO because of the increased right-side pressure of the heart and a resulting right-to-left shunt from the acute pulmonary embolism. Although pediatric cases of pulmonary embolism are rare, when diagnosed, clinicians should consider the risk of a concurrent paradoxical cerebral embolism resulting from a latent PFO. The possibility of PFO should be assessed extremely carefully in pediatric critical care by checking for a thrombogenesis tendency and the existence of deep vein thrombosis in the patient.

Clinical relevance of atrial septal aneurysm and patent foramen ovale with migraine

AIM

To test the potential association between atrial septal aneurysm (ASA) and migraine in patent foramen ovale (PFO) closure patients through an observational, single-center, case-controlled study.

METHODS

We studied a total of 450 migraineurs who had right-to-left shunts and underwent PFO closure in a retrospective single-center non-randomized registry from February 2012 to October 2016 on the condition that they were aged 18-45 years old. Migraine was diagnosed according to the International Classification of Headache Disorders, 3^rd edition and evaluated using the Headache Impact Test-6 (HIT-6). All patients underwent preoperative transesophageal echocardiography, contrast transthoracic echocardiography, and computed tomography or magnetic resonance imaging examinations, with subsequent fluoroscopy-guided PFO closure. Based on whether they have ASA or not, the patients were divided into two groups: A (PFO with ASA, n = 80) and B (PFO without ASA, n = 370). Baseline characteristics and procedural and follow-up data were reviewed.

RESULTS

Compared to group B, group A had an increased frequency of ischemic lesions (11.3% vs 6.2%, P = 0.038) and migraine with aura (32.5% vs 21.1%, P = 0.040). The PFO size was significantly larger in group A (P = 0.007). There was no significant difference in HIT-6 scores between the two groups before and at the one-year follow-up after the PFO closure [61 (9) vs 63 (9), P = 0.227; 36 (13) vs 36 (10), P = 0.706].

CONCLUSION

Despite its small sample size, our study suggests that the prevalence of ASA in PFO with migraine patients is associated with ischemic stroke, larger PFO size, and migraine with aura.

Iatrogenic atrial septal defect post mitral valve in valve implantation

A 75 year-old female with symptomatic severe mitral regurgitation of a bio-prosthetic valve secondary to valve leaflet perforation due to endocarditis underwent a mitral valve in valve replacement in an existing Hancock 27 mm valve using a trans-femoral/trans-septal approach. The procedure was complicated by an iatrogenic atrial septal defect post trans-septal puncture causing a severe right-to-left shunt due, possibly, to the combination of severe pulmonary hypertension and moderate tricuspid regurgitation the patient had suffered from at base line. Once the sheath was removed an immediate desaturation was observed which required emergent closure with an AMPLATZER ASD Occluder device (St. Jude Medical/Abbott Structural, St. Paul, Minnesota, MN). This stabilized the patient and returned her blood oxygen levels to normal. The case brings forth a rare but important complication that may occur during trans-septal procedures especially when using large sheaths. It emphasizes the importance of proper echocardiographic and hemodynamic evaluation prior to such procedures in order to be prepared for such complications.

[Paradoxical embolism: Myth or reality?]

Paradoxical embolism should be suspected in front of a clinical phenomenon of thromboembolism associated with an anatomical right-to-left shunt. Others potential cardiac sources of thromboembolism must be ruled out. Strokes constitute the most frequent clinical manifestations of paradoxical embolism. Right-to-left left shunts are in connection with intracardiac defects (atrial septal defect and patent foramen ovale) or pulmonary arteriovenous malformations. The probability that a discovered PFO is stroke-related can be evaluated by a score. Therapeutic approaches for secondary prevention of recurrent stroke include antithrombotic and/or percutaneous treatments. The choice strategy begins to be clearer with the recent results of randomized controlled studies.

Reliability of right-to-left shunt screening in the prevention of scuba diving related-decompression sickness

OBJECTIVES

The aim of this study was to investigate the relationship between right-to-left shunt (RLS) and the clinical features of decompression sickness (DCS) in scuba divers and to determine the potential benefit for screening this anatomical predisposition in primary prevention.

METHODS

634 injured divers treated in a single referral hyperbaric facility for different types of DCS were retrospectively compared to 259 healthy divers. All subjects had a RLS screening by contrast Transcranial Doppler (TCD) ultrasound according to a standardized method. The number of bubbles detected defined the degree of RLS (small if 5-20 bubbles, large if >20 bubbles).

RESULTS

TCD detected 63% RLS in DCS group versus 32% in the control group (p<0.0001) The overall prevalence of RLS was higher in divers presenting a cerebral DCS (OR, 5.3 [95% CI, 3.2-8.9]; p<0.0001), a spinal cord DCS (OR, 2.1 [95% CI, 1.4-3.1]; p<0.0001), an inner ear DCS (OR, 11.8 [95% CI, 7.4-19]; p<0.0001) and a cutaneous DCS (OR, 17.3 [95% CI, 3.9-77]; p<0.0001) compared to the control group, but not in divers experiencing ambiguous symptoms or musculoskeletal DCS. There was in increased risk of DCS with the size of RLS. The determination of diagnostic accuracy of TCD testing through the estimation of likelihood ratios revealed that predetermination of RLS did not change significantly the prediction of developing or not a DCS event.

CONCLUSION

The assessment of RLS remains indicated after an initial episode of spinal cord, cerebral, inner ear and cutaneous form of DCS but this approach is definitely not recommended in routine practice.

Different Valsalva Manoeuvre Procedures for the Diagnosis of Right-to-Left Shunt by Contrast-Transcranial Doppler

The main purpose of this study was to compare two contrast agent injection times during the Valsalva manoeuvre (VM) for the diagnosis of right-to-left shunt using contrast-transcranial Doppler (c-TCD). In total, 992 consecutive patients underwent testing. All patients underwent step 1, and then a coin toss was used to determine the order of steps 2 and 3. The following testing steps were repeated twice: (1) a contrast agent (CA) was infused at rest (CA at rest testing); (2) the VM was initiated immediately after CA injection and released 10 s after CA injection (CA pre-VM testing); and (3) a CA was injected 5 s after initiating the VM, which was released 5 s after CA injection (CA mid-VM testing). For the CA at rest, pre-VM and mid-VM groups, significant differences were observed in the positive right-to-left shunt diagnosis rates (11.49% vs. 23.08% vs. 26.11%, respectively, with an inter-group significance of p < 0.05) and grade classifications (p < 0.05). Although the times to first microbubble appearance were similar between the CA at rest and the CA pre-VM groups (8.96 ± 3.40 s vs. 8.42 ± 3.72 s, p > 0.05), it was shorter (6.4 ± 2.75 s, p < 0.05) for the CA mid-VM group than for the other two groups. For the c-TCD testing, the CA mid-VM group yielded different results for diagnosing right-to-left shunts relative to the CA pre-VM group.

Migraine and percutaneous patent foramen ovale closure: a systematic review and meta-analysis

Background

The association between patent foramen ovale (PFO) and migraine with aura (MA) is well established. However, the benefits of PFO closure are less certain in patients with migraine without aura (MwoA).

Methods

We systematically searched Pubmed for pertinent clinical studies published from January 2000 to July 2015. The primary end-point was the elimination or significant improvement of migraine symptoms after PFO closure.

Results

Upon screening an initial list of 315 publications, we identified eight studies that included 546 patients. Overall, our analysis indicated a significant improvement of migraine in 81% of MA cases compared to only 63% of MwoA cases. The summary odds ratio was 2.5 (95% confidence interval 1.09–5.73), and the benefits of PFO closure were significantly greater for patients with MA compared to patients with MwoA (P = 0.03).

Conclusions

The presence of aura provides a reference standard for the clinical selection of patients with migraine for PFO closure intervention.

Electronic supplementary material

The online version of this article (doi:10.1186/s12872-017-0644-9) contains supplementary material, which is available to authorized users.

Identification and Quantification of Patent Foramen Ovale-Mediated Shunts: Echocardiography and Transcranial Doppler

Once deemed benign, patent foramen ovale (PFO)-mediated right-to-left shunting has now been linked to stroke, migraine, and hypoxemia. Contrast transesophageal echocardiography is considered the standard technique for identifying a PFO, allowing visualization of the atrial septal anatomy and differentiation from non-PFO right-to-left shunts. Transthoracic echocardiography is the most common method for PFO imaging, being cost-effective, but has the lowest sensitivity. Transcranial Doppler is highly sensitive but is unable to differentiate cardiac from pulmonary shunts; it is the best method to quantitate shunt severity, being more sensitive than transthoracic or transesophageal echocardiography so is our preferred screening method for PFO.

The relationship between right-to-left shunt and brain white matter lesions in Japanese patients with migraine: a single center study

BACKGROUND

There may be a link between right-to-left shunt (RLs) and brain white matter lesions (WMLs) in patients with migraine. In this study, we assessed the relationship between WMLs and RLs in Japanese migraine patients.

METHODS

A total of 107 consecutive patients with migraine with (MA) and without aura (MWOA) were included in this study. Contrast transcranial Doppler ultrasound was used to detect RLs. WMLs were graded using brain magnetic resonance imaging based on well-established criteria.

FINDINGS

The prevalence of RLs was significantly increased in the WMLs positive group (n = 24) compared with the WMLs negative group (n = 83) (75.0% vs. 47.0%, p = 0.015). In prevalence of WMLs between MA and MWOA patients, there were no statistical differences (p = 0.410). Logistic regression analysis adjusted by age and disease duration of migraine identified an RLs-positive status as the sole determinant for the presence of WMLs (OR = 6.15; 95% CI 1.82-20.8; p = 0.003) CONCLUSION: Our study suggests a possible link between RLs and WMLs in Japanese patients with migraine.

Ventilation/perfusion ratio and right to left shunt in healthy newborn infants

Oxygenation impairment can be assessed non-invasively by determining the degree of right-to-left shunt and ventilation/perfusion (V_A/Q) inequality. These indices have been used in sick newborn infants, but normative values have not been reported which are essential to determine the magnitude of the abnormality. We, therefore, aimed to measure the shunt and V_A/Q in infants with no history of respiratory conditions and determine if there was any effect of supine or prone position and the reproducibility of the data. Data were analysed from infants who had undergone a hypoxic challenge and in a subset who had been assessed in the supine or prone position. Transcutaneous oxygen saturations (SpO₂) were recorded at fractions of inspired oxygen (F_IO₂) of 0.21 and 0.15. Two independent raters used a computer software algorithm which analysed and fitted paired data for F_IO₂ and SpO₂ and derived a curve which represented the best fit for each infant's data and calculated the shunt and V_A/Q. The raters ability to interpret the SpO₂ value which corresponded to a given F_IO₂ was compared. The downwards displacement of the F_IO₂ versus SpO₂ curve was used to estimate the degree of right-to-left shunt and the rightwards shift of the curve was used to calculate the V_A/Q ratio. The mean (SD) gestational age of the 145 infants was 39 (1.6) weeks, their birth weight was 2990 (578) gms and median (range) postnatal age at measurement 3 (1-8) days. The mean (SD) V_A/Q ratio was 0.95 (0.21). None of the infants had a right-to-left shunt. No significant differences were found in V_A/Q in the supine compared to the prone position. The intraclass correlation coefficient of V_A/Q between two independent raters was 0.968 (95% CI 0.947-0.980), p < 0.001. Right-to-left shunt and V_A/Q ratio in healthy newborn infants were similar in the prone compared to the supine position.

Non-nosocomial healthcare-associated left-sided Pseudomonas aeruginosa endocarditis: a case report and literature review

Background

With the development of invasive medical procedures, an increasing number of healthcare-associated infective endocarditis cases have been reported. In particular, non-nosocomial healthcare-associated infective endocarditis in outpatients with recent medical intervention has been increasingly identified.

Case presentation

A 66-year-old man with diabetes mellitus and a recent history of intermittent urethral self-catheterization was admitted due to a high fever. Repeated blood cultures identified Pseudomonas aeruginosa, and transesophageal echocardiography uncovered a new-onset severe aortic regurgitation along with a vegetative valvular structure. The patient underwent emergency aortic valve replacement surgery and was successfully treated with 6 weeks of high-dose meropenem and tobramycin. Historically, most cases of P. aeruginosa endocarditis have occurred in the right side of the heart and in outpatients with a history of intravenous drug abuse. In the case presented, the repeated manipulations of the urethra may have triggered the infection. Our literature review for left-sided P. aeruginosa endocarditis showed that non-nosocomial infection accounted for nearly half of the cases and resulted in fatal outcomes as often as nosocomial cases. A combination therapy with anti-pseudomonal beta-lactams or carbapenems and aminoglycosides may be the preferable treatment. Medical treatment alone may be effective, and surgical treatment should be carefully considered.

Conclusions

We presented a rare case of native aortic valve endocarditis caused by P. aeruginosa. This case illustrates the importance of identifying the causative pathogen(s), especially for outpatients with a recent history of medical procedures.

Comparison of Different Methods of Valsalva Maneuver for Right-to-left Shunt Detection by Contrast-Enhanced Transcranial Doppler

We evaluated 298 patients for right-to-left shunt (RLS) detection by contrast-enhanced transcranial Doppler at rest state (RS), during the conventional Valsalva maneuver (CM), and during the modified Valsalva maneuver (BM: blowing into the connecting tube of a sphygmomanometer at 40 mm Hg for 10 s) in random order, and the degree of RLS along the time of the first microbubble occurrence was recorded. The positive rates were 21.8%, 36.9% and 47.3% for RS, CM and BM, respectively (p < 0.001). BM resulted in a significantly higher positive rate (p = 0.010), and there was a significant difference between the two different methods of VM in terms of the degree of RLS detection (p < 0.001). Further, the first microbubble occurred later during BM than CM (10.22 ± 3.77 s vs. 9.44 ± 4.36 s, p < 0.05). This modified maneuver is an alternative to the conventional one, especially for those who cannot perform the conventional maneuver adequately, but are highly suspected of having RLS.

Recognition of Undiagnosed Neonatal Heart Disease

Heart defects are the most common congenital malformation. Approximately 8000 infants per year in the United States require diagnosis in the newborn period to avoid severe injury or death. It is incumbent on the neonatologist and pediatrician to expeditiously detect the presence of symptomatic heart disease so that infants can be stabilized before cardiovascular decompensation. Evaluating infants and further categorizing them into the particular pathophysiology are necessary to stabilize them in anticipation of more definitive care by the pediatric cardiac team.

Body positions in the diagnosis of right-to-left shunt by contrast transcranial Doppler

Contrast transcranial Doppler (c-TCD) is sensitive in detecting right-to-left shunt (RLS). However, the methodology and ideal posture are controversial. Consecutive migraine patients were prospectively examined for RLS using c-TCD. Each patient was examined while at rest and subsequently with the Valsalva maneuver (VM) in three positions: supine, left lateral decubitus and right lateral decubitus. RLS was diagnosed with at least one microbubble detected at any position. RLS was highest in the left lateral decubitus position, both during rest and with VM. The left lateral decubitus position was associated with the highest total number of microbubbles and greater shunt grades. Patients who tested positive in the other two positions had the lowest index position failure rate during rest in the left lateral decubitus position. In some patients in whom RLS is detected at rest, it may not be detected (false negative) under VM. To ensure c-TCD's the sensitivity to RLS, testing in the left lateral decubitus position at rest and under VM is suggested; testing in other positions is necessary to avoid false negatives.

The role of persistent foramen ovale and other shunts in decompression illness

A persistent foramen ovale (PFO) and other types of right-to-left shunts are associated with neurological, cutaneous and cardiovascular decompression illness (DCI). A right-to-left shunt is particularly likely to be implicated in causation when these types of DCI occur after dives that are not provocative. It is believed that venous nitrogen bubbles that form after decompression pass through the shunt to circumvent the lung filter and invade systemic tissues supersaturated with nitrogen (or other inert gas) and as a result there is peripheral amplification of bubble emboli in those tissues. Approximately a quarter of the population have a PFO, but only a small proportion of the population with the largest right-to-left shunts are at high risk of shunt-mediated DCI. The increased risk of DCI in people with migraine with aura is because migraine with aura is also associated with right-to-left shunts and this increased risk of DCI appears to be confi ned to those with a large PFO or other large shunt. Various ultrasound techniques can be used to detect and assess the size of right-to-left shunts by imaging the appearance of bubble contrast in the systemic circulation after intravenous injection. In divers with a history of shunt-mediated DCI, methods to reduce the risk of recurrence include cessation of diving, modification of future dives to prevent venous bubble liberation and transcatheter closure of a PFO.

Atrial septal defect: a coincidental finding on a screening medical

An otherwise fit, healthy medical practitioner who was a recreational diver underwent a medical assessment for a remote posting as an Antarctic Medical Practitioner at which a coincidental finding of an atrial septal defect (ASD) was made. ASDs can have health implications in extreme environments such as high altitude and is contraindicated in scuba diving. ASDs are common, being present in 1:1,500 live births and comprise 10% of all cardiac abnormalities. In this case, a percutaneous occlusive device was inserted under general anaesthetic with subsequent improvements in the practitioner's exercise capacity, return to diving and full employment, including Antarctic deployment, and right-sided heart remodelling 18 months post closure.

Systemic-to-pulmonary venous shunt in a patient with non-Hodgkin lymphoma: A case report and review of the literature

We describe a case of a systemic-to-pulmonary venous shunt secondary to superior vena cava obstruction in a patient with newly diagnosed non-Hodgkin lymphoma. This rare condition manifested with symptoms of dyspnea and hypoxemia that were out of proportion to the pleural effusion diagnosed on chest imaging. Standard treatment of such rare collateral plexuses is observation. However, it is important for clinicians to be cognizant that in rare cases such plexuses can lead to right-to-left shunt complications such as embolism.

Effects of patient position on right-to-left shunt detection by contrast transcranial Doppler

Contrast-enhanced transcranial Doppler (c-TCD) was performed on 117 patients to detect a right-to-left shunt (RLS). Each patient was examined during normal breathing and after performing the Valsalva maneuver (VM) in three randomly ordered positions: supine, left lateral decubitus and sitting upright. When breathing normally, RLS-positive rates were 15.4%, 23.1% and 28.2% for supine, left lateral decubitus and upright sitting positions, respectively. After VM, the positive rates were 25.6%, 28.2% and 36.8%, respectively. For each position, the RLS-positive rates were higher after VM than normal breathing and higher for the left lateral decubitus and upright sitting positions compared with the supine position, irrespective of breathing. There were no significant differences between findings for the left lateral decubitus and upright sitting positions. No significant differences in shunt grades were found across all groups. The choice of position for patients undergoing c-TCD can improve its sensitivity for the diagnosis of RLS.

Right-to-left interatrial shunt secondary to right hemidiaphragmatic paralysis: an unusual scenario for urgent percutaneous closure of patent foramen ovale

A 66 year-old female presented with a refractory hypoxaemia in association with an isolated paralysis of the right hemidiaphragm. Transoesophageal echocardiography (TEE) with both colour Doppler and bubble test demonstrated a significant patent foramen ovale (PFO)-mediated right-to-left shunt (RTLS) without an increased interatrial pressure gradient. The PFO was urgently closed by deployment of an AMPLATZER(®) occluder device, resulting in complete recovery of the arterial oxygen saturation and patient's symptoms. As noted on TEE, the RTLS was due to redirection of blood flow from the inferior vena cava directly through the PFO secondary to distortion of the cardiac anatomy by right hemidiaphragmatic paralysis.