Variations in Azygos Venous System in The Eastern Indian Population: A Cadaveric Study

Background: This study aimed to classify Azygos vein patterns in the Eastern Indian population. Methods: During the routine dissection of MBBS in the 2018–2020 academic year, 20 formalin embalmed cadavers aged 50–70 were used to classify the azygos system. The cadaver’s age was verified by its entry into our institute’s anatomy register. The register confirmed that all cadavers used for dissection were of Indian origin. Though gender was not compared in this study, it was noted for record purposes by identifying the external genitalia and confirming it to the records. These were the exclusion criteria: 1) No major thoracic surgeries; 2) No major thoracic deformities. Azygos, hemiazygos, and accessory hemiazygos veins were also examined. Results: The Anson & McVay system was used to classify the recruited cadavers’ azygos system. The cadavers were classified into Type-1, Type-2, and Type-3. Type 2 was again subdivided into 5 subgroups and Type-3 into2 sub-groups. In one cadaver, Type-1 was observed, 17 cadavers had Type-2 azygos system and 2 cadavers showed Type-3. Of the 17 cadavers of Type-2, 3 and 7 cadavers had Type-2A and -2B, respectively. Similarly, 4 and 1 cadavers had 2C and 2D patterns, respectively. Also, 2 cadavers showed 2E type. Of the 2 cadavers of Type-3, one was Type -3A and one Type-3B. The termination of the azygos vein vertebral level was between T2 and T4, of the hemiazygos vein was T8 to T11, and accessory hemiazygos veins were between T7 and T10. Conclusion: These variations should be well studied to avoid misinterpretation during radiological investigations and surgical interventions.

Damage control surgery for thoracic outlet vascular injuries: the new resuscitative median sternotomy plus REBOA / Cirugía de control de daños para lesiones del opérculo torácico: nuevo abordaje mediante esternotomía mediana y REBOA

Abstract Thoracic vascular trauma is associated with high mortality and is the second most common cause of death in patients with trauma following head injuries. Less than 25% of patients with a thoracic vascular injury arrive alive to the hospital and more than 50% die within the first 24 hours. Thoracic trauma with the involvement of the great vessels is a surgical challenge due to the complex and restricted anatomy of these structures and its association with adjacent organ damage. This article aims to delineate the experience obtained in the surgical management of thoracic vascular injuries via the creation of a practical algorithm that includes basic principles of damage control surgery. We have been able to show that the early application of a resuscitative median sternotomy together with a zone 1 resuscitative endovascular balloon occlusion of the aorta (REBOA) in hemodynamically unstable patients with thoracic outlet vascular injuries improves survival by providing rapid stabilization of central aortic pressure and serving as a bridge to hemorrhage control. Damage control surgery principles should also be implemented when indicated, followed by definitive repair once the correction of the lethal diamond has been achieved. To this end, we have developed a six-step management algorithm that illustrates the surgical care of patients with thoracic outlet vascular injuries according to the American Association of the Surgery of Trauma (AAST) classification.

Resumen El trauma vascular torácico está asociado con una alta mortalidad y es la segunda causa más común de muerte en pacientes con trauma después del trauma craneoencefálico. Se estima que menos del 25% de los pacientes con una lesión vascular torácica alcanzan a llegar con vida para recibir atención hospitalaria y más del 50% fallecen en las primeras 24 horas. El trauma torácico penetrante con compromiso de los grandes vasos es un problema quirúrgico dado a su severidad y la asociación con lesiones a órganos adyacentes. El objetivo de este artículo es presentar la experiencia en el manejo quirúrgico de las lesiones del opérculo torácico con la creación de un algoritmo de manejo quirúrgico en seis pasos prácticos de seguir basados en la clasificación de la AAST. que incluye los principios básicos del control de daños. La esternotomía mediana de resucitación junto con la colocación de un balón de resucitación de oclusión aortica (Resuscitative Endovascular Balloon Occlusion of the Aorta - REBOA) en zona 1 permiten un control primario de la hemorragia y mejoran la sobrevida de los pacientes con trauma del opérculo torácico e inestabilidad hemodinámica.

Connecting hepatic vein and azygos vein by an autologous pericardial conduit to complete a Fontan procedure through a unilateral thoracotomy: A case report / 中国胸心血管外科临床杂志

@#We reported a case of a six-year-old boy diagnosed of single ventricle, pulmonary atresia and interrupted inferior vena cava. After modified Blalock-Taussig shunt and bidirectional Glenn procedure, he received the Fontan procedure. The Fontan procedure was done through a unilateral thoracotomy, using an autologous pericardial conduit to connect hepatic vein and azygos vein. The result of short-term follow-up was satisfactory.

Staged Repair of Unilateral Absence of the Right Proximal Pulmonary Artery Using Autologous Azygos Vein Graft Interposition / 日本心臓血管外科学会雑誌

The isolated unilateral absence of a proximal pulmonary artery is a rare congenital lesion that presents various symptoms. Although some reports have shown one-stage reconstruction of the pulmonary circulation in infants, the two-stage approach is required in the situation of pulmonary arterial hypoplasia. In these cases, the usual approach is systemic pulmonary shunting for the first operation, to obtain growth of the pulmonary vascular bed, and then connecting bilateral pulmonary arteries for the second operation. Moreover, in the majority of patients without a right proximal pulmonary artery, some material is required for reconstructive surgery that corresponds to the patient's growth. A girl aged 2 years and 10 months with absent right proximal pulmonary artery, underwent modified Blalock-Taussig shunting with a free autograft of the azygos vein. The shunt was banded to prevent excessive pulmonary blood flow. Reconstructive surgery was performed 10 months after the first operation. At the second operation, growth of the right distal pulmonary artery and azygos autograft was satisfactory. Therefore, we used this autograft as an interposed graft of the right and main pulmonary arteries. Her postoperative course was uneventful. We advocate the usefulness of the azygos vein for graft material possessing the possibility of growth. This autograft is useful for pulmonary arterial reconstruction, such as the present case, and also may be useful for a systemic-pulmonary shunt, while growth is anticipated for more complex heart diseases.

Variations In Formation And Termination Of Azygos Vein In South Indian Population

Objectives: To study the variations in formation, termination and its level of azygos vein in embalmed humancadavers.Materials and Methods: The present study sample comprised of thorax of 50 embalmed human cadaversirrespective of their sex and age. The specimens were studied by dissection method at the Department of Anatomy,KIMS Bengaluru and other medical colleges in around the Bengaluru.The parameters were noted meticulouslyand the data processed.Results: Out of 50 specimens studied, in 42 specimens (84%) azygos vein formed only by lateral root, by 2 rootsin 5 specimens (10%). All the three roots, the lateral, intermediate and medial roots together formed the azygosvein in 3 specimens (6%).In all the specimens the azygos vein was terminating into superior vena cava. Formationof azygos vein was at the lower border of T12 in 28 specimens (56%) and termination was at the upper border ofT5 in 43 specimens (86%).Conclusion: The result of the study showed the variations in the formation of azygos vein and its level of formationand termination. The variation has been discussed in detail and this knowledge forms the basis for surgical andother radiological procedures in the posterior mediastinum.

Characteristics and prognosis of interrupted inferior vena cava with azygous continuation / 中华妇产科杂志

Objective To explore the clinical characteristics of interrupted of the inferior vena cava with azygous continuation and the prognosis.Methods Retrospective analysis of 21 fetuses diagnosed with interrupted inferior vena cava with azygous continuation among 28 567 pregnant women who underwent routine ultrasound scan.The clinical data,ultrasonographic features,genetic information and prognosis were collected. Results Interrupted of the inferior vena cava with azygous continuation occurred in 21(0.07%, 21/28 567)of 28 567 patients.Three fetuses(14%,3/21)complicated with heart and extracardiac malformations, including endocardiac cushion defect,single atrium and single ventricle,double superior vena cava,dextrocardia, asplenia syndrome,visceral heterotaxy,duodenal atresia;six fetuses(29%,6/21)were associated with cardiac anomalies, such as hypoplastic left heart syndrome, double outlet right ventricle, pulmonary stenosis, ventricular septal defect,persistent left superior vena cava,endocardiac cushion defect and transposition of the great arteries;six cases(29%,6/21)were only combined with extracardiac malformations,includingasplenia syndrome, visceral heterotaxy, duodenal atresia. Three fetuses (14%,3/21) were nonorganic abnormalities included thickening of the right ventricle wall, fetal bradycardia, pericardial effusion, hydrops abdominis, increased peak systolic velocity/end diastolic velocity and single umbilical artery.Three fetuses(14%,3/21) were isolated interrupted inferior vena cava with azygous continuation,but without other anomalies and 2 of them had normal fetal karyotype.Five cases(24%,5/21)were successfully vaginal delivery,1 case(5%,1/21) had cesarean section. After 12-40 months follow-up, we didn′t obeserve obviously abnormality, nor any chromosomal abnormality.Ten patients(48%,10/21)opted for termination of the pregnancy and the autopsies were not done.Five cases(24%,5/21)were lost to follow up.Conclusions Interrupted inferior vena cava with azygous continuation are associated with cardiovascular and extracardiac anomalies, cardiac malformation and visceral heterotaxy are the most common anomalies. Visceral heterotaxy should be considered and fetal karyotype should be suggested. In the cases of isolated interrupted inferior vena cava with azygous continuation and normal karyotype,the outcome is favorable.

Anatomical study of the atypical azygos venous system and its clinical significance / 局解手术学杂志

Objective To investigate the morphology and classification of the atypical azygos venous system,and to provide reference for diagnosis and treatment of mediastinal and thoracic vascular diseases.Methods Thirty cadavers were perfused with 10%formalin solution, and immersed in the solution for one month before dissection.The vertebral levels of termination and diameters of the azygos,hemiazygos and accessory hemiazygos veins were examined.Results There were 24 cases of classical azygos venous system,which contained the azygos, hemiazygos and accessory hemiazygos veins.And there were 6 cases of atypical azygos venous system,which were further divided into 4 sub-groups.Namely,type a(2 cases)which showed an inverted"Y"shape;type b(2 cases)which was single column with hemiazygos and ac-cessory hemiazygos veins absent;type c(1 case)which showed an accessory hemiazygos vein draining into the left brachiocephalic vein;and type d(1 case)with azygos vein and double superior vena cava variation.Diameters of termination of the azygos,hemiazygos and accessory hemiazygos veins were(10.39 ±1.98)mm,(8.51 ±2.28)mm,and(6.29 ±1.56)mm,respectively.The vertebral levels of termination of the azygos,hemiazygos and accessory hemiazygos veins were T 4(83.3%),T7to T10,T4to T8respectively.Conclusion All morphometrical diameters and their termination levels can be used during preoperative CT evaluations before planning invasive mediastinal procedures.The re-sults of this study could be helpful in mediastinal surgery,mediastinoscopy and the surgery of the deformations of the vertebral column in the thoracic cavity.

Study on Reference Value of Fetal Azygos Vein and Its Relationship with Gestational Age / 中国医学影像学杂志

Purpose To establish normative reference ranges of fetal azygos vein between gestation 20.0 and 40.0 weeks and analyze the possible correlation between azygos vein diameter and gestational age.Materials and Methods Retrospectively analyzed the data which collected from pregnant women with singleton pregnancies,1375 fetuses with normal outcome were included.The gestation was from 20.0 weeks to 40.0 weeks.The research objects were divided into 5 groups according to their gestational age and were examined standardized.The fetal normal reference value of azygos vein and its correlation with gestational ages were analyzed.Results The normal reference value of the fetal azygos vein diameter was established.We found that a significant increase linear between the diameter of fetal azygos vein and the gestation age.There was no obvious correlation with sex.The ratio of azygos vein and descending aorta inner diameter was about 0.36.There was on obvious changes in different gestational ages.Conclusions Fetal echocardiography technology can accurately assess fetal cardiac structure,the establishment normal reference value of azygos vein diameter could provide guidance for fetal echocardiography examination.

Pre-aortic inter-azygos veins: two case reports / Venas interácigos pre-aórticas: reporte de dos casos

This report describes two cases of multiple anomalies associated with the azygos venous system. In Case 1, the hemiazygos vein drained the 9th to 11th left posterior intercostal veins. At T9 vertebral level, the interazygos vein passed obliquely and anterior to the aorta to drain into the azygos vein on the right. In Case 2, the common venous trunk formed by the accessory hemiazygos and hemiazygos veins passed anterior to the aorta to drain into the azygos vein at T9 vertebral level. These findings represent pre-aortic inter-azygos veins, which is a rare variation of the azygos venous system. Pre-aortic inter-azygos veins can mimic pathologies such as enlarged lymph nodes, tumors and aneurysms leading to misinterpretation of radiographs, computerized tomography and magnetic resonance scans. Surgeons need to be aware of this type of variation so as to avoid injury of any anomalous passing venous vessels.

Este informe describe dos casos de múltiples anomalías asociadas con el sistema venoso ácigos. En el caso 1, la vena ácigos drena las 9 y 11 venas intercostales posteriores izquierdas. A nivel de la 9 vértebra torácica, la vena interácigos pasó oblicuamente y anterior a la aorta para drenar en la vena ácigos del lado derecho. En el caso 2, el tronco venoso común formado por las venas hemiácigos accesoria y hemiácigos pasaron anterior a la aorta para drenar en la vena ácigos a nivel de la 9 vértebra torácica. Estos resultados representan venas interácigos pre-aórticas, que es una rara variación del sistema venoso ácigos. Las venas interácigos pre-aórticas pueden imitar patologías, como agrandamiento de nódulos linfáticos, tumores y aneurismas que conducen a una mala interpretación de las exploraciones por radiografías, tomografía computarizada y resonancia magnética. Los cirujanos deben ser conscientes de estos tipos de variaciones para evitar lesionarlos.

Accidental catheterization of epidural venous plexus: tomographic analysis / Cateterização acidental do plexo venoso peridural: análise tomográfica

ABSTRACT BACKGROUND AND OBJECTIVES: Inadvertent venous catheterizations occur in approximately 9% of lumbar epidural anesthetic procedures with catheter placement and, if not promptly recognized, can result in fatal consequences. The objective of this report is to describe a case of accidental catheterization of epidural venous plexus and its recording by computed tomography with contrast injection through the catheter. CASE REPORT: A female patient in her sixties, physical status II (ASA), underwent conventional cholecystectomy under balanced general anesthesia and an epidural with catheter for postoperative analgesia. During surgery, there was clinical suspicion of accidental catheterization of epidural venous plexus because of blood backflow through the catheter, confirmed by the administration of a test dose through the catheter. After the surgery, a CT scan was obtained after contrast injection through the catheter. Contrast was observed all the way from the skin to the azygos vein, passing through anterior and posterior epidural venous plexuses and intervertebral vein. CONCLUSION: It is possible to identify the actual placement of the epidural catheter, as well as to register an accidental catheterization of the epidural venous plexus, using computed tomography with contrast injection through the epidural catheter.

RESUMO JUSTIFICATIVA E OBJETIVOS: A cateterização venosa inadvertida ocorre em aproximadamente 9% das anestesias peridurais lombares com introdução de cateter e caso não seja prontamente reconhecida pode trazer consequências fatais. O objetivo deste relato é descrever um caso de cateterização acidental do plexo venoso peridural e o seu registro por tomografia computadorizada com injeção de contraste pelo cateter. RELATO DE CASO: Paciente feminina, sexagenária, estado físico II (ASA), submetida à colecistectomia convencional sob anestesia geral balanceada e peridural com cateter para analgesia pós-operatória. Durante cirurgia houve suspeição clínica de cateterização acidental do plexo venoso peridural, por refluxo de sangue pelo cateter, fato confirmado pela administração de dose-teste pelo cateter. Feita tomografia computadorizada com injeção de contraste pelo cateter, após o termino da cirurgia. Observado todo o trajeto do contraste desde a pele até a veia ázigo, passando pelo plexo venoso peridural anterior, posterior e veia intervertebral. CONCLUSÃO: É possível a identificação do real posicionamento do cateter peridural, bem como o registro da cateterização acidental do plexo venoso peridural, por meio de tomografia computadorizada com injeção de contraste pelo cateter peridural.

Extracorporeal Membrane Oxygenation Cannula Malposition in the Azygos Vein in a Neonate with Right-Sided Congenital Diaphragmatic Hernia / 대한중환자의학회지

Malposition of the extracorporeal membrane oxygenation (ECMO) venous cannula in the azygos vein is not frequently reported. We hereby present such a case, which occurred in a neonate with right-sided congenital diaphragmatic hernia. Despite ECMO application, neither adequate flow nor sufficient oxygenation was achieved. On the cross-table lateral chest radiograph, the cannula tip was identified posterior to the heart silhouette, which implied malposition of the cannula in the azygos vein. After repositioning the cannula, the target flow and oxygenation were successfully achieved. When sufficient venous flow is not achieved, as in our case, clinicians should be alerted so they can identify the cannula tip location on lateral chest radiograph and confirm whether malposition in the azygos vein is the cause of the ineffective ECMO.

Extracorporeal Membrane Oxygenation Cannula Malposition in the Azygos Vein in a Neonate with Right-Sided Congenital Diaphragmatic Hernia / 대한구급학회지

Malposition of the extracorporeal membrane oxygenation (ECMO) venous cannula in the azygos vein is not frequently reported. We hereby present such a case, which occurred in a neonate with right-sided congenital diaphragmatic hernia. Despite ECMO application, neither adequate flow nor sufficient oxygenation was achieved. On the cross-table lateral chest radiograph, the cannula tip was identified posterior to the heart silhouette, which implied malposition of the cannula in the azygos vein. After repositioning the cannula, the target flow and oxygenation were successfully achieved. When sufficient venous flow is not achieved, as in our case, clinicians should be alerted so they can identify the cannula tip location on lateral chest radiograph and confirm whether malposition in the azygos vein is the cause of the ineffective ECMO.

Complicated Azygos Vein Aneurysm in an Infant Presenting with Acute Pulmonary Thromboembolism

Azygos vein aneurysm is a rare cause of mediastinal mass. Most cases present as an incidental finding on imaging modalities, but in few cases the thrombosis in the aneurysm leads to pulmonary thromboembolism, which may require surgical resection. We present a case where, for the first time, a case of a complicated azygos vein aneurysm was diagnosed in infancy, which required surgical resection.

Anomalous azygos veins - its embryological basis and clinical significance.

Background: The anatomical knowledge of the variability of the azygos venous system is important for the surgical interventions of the posterior mediastinum and also during radiological investigations/diagnosis especially CT and MRI. The variant azygos venous system might be confused with thoracic aorta aneurysms, lymphadenopathy and tumours of posterior mediastinum. Methods: The present study was undertaken on 10 embalmed adult human cadavers irrespective of sex, used for undergraduate dissection from the Department of Anatomy, Mandya Institute of Medical Sciences, Mandya. In this present study, formation, course and termination pattern of azygos system of veins was observed in 10 dissected human cadavers. Out of which 2 cadavers showed different types of variations. Results: In the present study, normal azygos venous system was found in 8 specimens accounting for 80%. Variations were found in 2 specimens (20%); one specimen presented with connection between accessory hemiazygos vein and hemiazygos vein, 3 transverse channels across vertebral column and the other specimen showed absence of accessory hemiazygos vein and shifting of azygos vein towards midline. Conclusions: Accurate knowledge about these kinds of variations is very important to identify, especially in the computed tomography and magnetic resonance imaging of mediastinum. The abnormal azygos venous system may easily be confused with aneurysm, lymphadenopathy and other abnormalities like tumor. It is important to keep these kinds of variations in mind while performing the mediastinal operations or surgery of large vessels.

Clinical value of interrupted inferior vena cava in prenatal diagnosis of isomerism / 中华围产医学杂志

Objective To analyze the ultrasonic features of interrupted inferior vena cava (IVC) and its relationship with related deformities so as to improve the prenatal diagnosis of isomerism.Methods Pregnant women who received prenatal care in Peking University People's Hospital or who were referred to our hospital for suspected malformation of fetus between January 2010 and December 2013 were enrolled in this study.Fetal echocardiography and abdominal transverse section were performed routinely.Spatio-temporal image correlation technology was used to further clarify interrupted IVC if azygos vein was broadened or IVC disappeared in the fetal abdominal transverse sections.Based on the presence of cardiac structural abnormalities,interrupted IVC was divided into isolated IVC interruption and complex IVC interruption.Neonatal echocardiography was performed in women with continued pregnancies.In women with terminated pregnancy,fetus was autopsied after induced labor.Results In total,12 cases of interrupted IVC were diagnosed,including 5 cases of isolated IVC interruption with full-term delivery and 7 cases of complex IVC interruption.Neonatal echocardiography,abdominal ultrasound were all normal in the 5 cases of isolated IVC interruption except for 3 cases complicated with sistus inversus viscerum.All the 7 cases of complex IVC interruption had induced labor because of some congenital cardiac abnormalities.Autopsy showed that 6 cases had left isomerism,and 1 case had right isomerism.Conclusions Interrupted IVC can be easily identified in prenatal diagnosis due to the typical ultrasonic features.Complication with some congenital cardiac abnormalities often indicates isomerism,especially left isomerism.

Atypic Drainage Pattern of Posterior Intercostal Veins Into the Azygos Venous System.

The azygos venous system vary greatly in theirmode of origin, course,tributaries, anastomoses and termination which resulst predominantly due to its complex embryological development. Azygos venous system develops as right and left azygos venous lines. Right azygos venous line develops into vertical part of azygos vein whereas the left one develops into accessory hemiazygos and inferior hemiazygos veins. These are connected by subcentral/ transvertebral veins. In the present case, we found an atypic drainage pattern of posterior intercostal veins into azygos venous system, left being more variable. Right superior intercostal vein formed by 2nd and 3rd posterior intercostal veins whereas left superior intercostal vein was found to be absent. 2nd, 3rd, 4th& 5th left posterior intercostal veins thus drained into accessory hemiazygos vein. Sixth and seventh left PICVs formed a common trunkwith accessory hemiazygous vein and drained into the azygous vein at T6 level. Eighth one united with the hemiazygos vein and formed a common trunkwhich drained into azygos vein at T8 level. Such variations of the azygos venous system are important for a clinician during mediastinal surgeries to prevent inadvertent hemorrhagic complications.

Anatomic variation of thorax drainage: absence of accessory hemiazygos vein

Formed by the azygos, hemiazygos and accessory hemiazygos veins, this system is responsible for the venous drainage of the thorax and partially of the abdomen. Abnormalities of this system are not uncommon, and many are referred to in literature. The complete agenesis of the accessory hemyazigos vein is associated with complete regression of the left posterior cardinal vein or atrophy of the left subcardinal vein. The reported case consists of the complete absence of the accessory hemiazygos vein, culminating in the drainage of the 4th, 5th, 6th, 7th and 8th left posterior intercostal veins directly into the azygos vein of a male cadaver. The importance of the theme is due to the necessity of recognizing patterns and frequencies of these variations when facing procedures addressing the mediastinum or the major vessels.

Implante de eletrodo em veia ázigos: uma opção terapêutica para limiar de desfibrilação elevado / Azygos vein lead implantation: a therapeutic option for elevated defibrillation threshold

A avaliação do limiar de desfibrilação (DFT) durante o implante do cardioversor-desfibrilador (CDI) é uma etapa relevante do procedimento, uma vez que, em até 16% dos pacientes, podemos encontrar elevados DFT. Relatamos o caso de um paciente portador de cardiomiopatia dilatada (CMPD) idiopática submetido a implante de CDI biventricular. Durante o procedimento, apresentou elevado DFT e se mostrou resistente às modalidades terapêuticas usuais. Optamos pelo implante de eletrodo de desfibrilação em veia ázigos, com resolução do quadro.

The evaluation of the defibrillation threshold (DFT) during the implantation of a cardioverter-defibrillator (ICD) is an important stage of the procedure, as a high DFT can be found in up to 16% of patients. We report a patient with idiopathic dilated cardiomyopathy (DCM) submitted to a biventricular ICD implantation. During the procedure, the patient showed a high DFT and showed to be resistant to usual therapeutic modalities. We opted for the azygos vein defibrillation lead implantation, with good resolution.

A Case of Septic Azygos Vein Embolism Caused by Staphylococcus aureus Bacteremia / 결핵및호흡기질환

A Septic embolism is a type of embolism infected with bacteria containing pus. These may become dangerous if dislodged from their original location. Embolisms of this type in the azygos vein are potentially fatal. The diagnosis of septic azygos vein embolism is difficult, so rapid diagnosis and treatment is important to avoid complications. Generally, treatment is enough for appropriate antibiotic therapy without anticoagulant therapy. We report a case of staphylococcal septic embolism in the azygos vein, which was discovered in a 51-year-old man exhibiting chest pain, dyspnea and fever. The patient was treated with antibiotic therapy alone without the use of anticoagulants.

Umbral de desfibrilación elevado: ¿los vectores de desfibrilación son importantes?: Are Defibrillation Vectors Important? / Elevated Defibrillation Threshold / Elevated Defibrillation Threshold: Are Defibrillation Vectors Important?

La evaluación del umbral de desfibrilación (UDF) es una práctica habitual en la mayoría de los implantes de cardiodesfibriladores implantables (CDI). La práctica estándar busca obtener una desfibrilación exitosa de la fibrilación ventricular. En pacientes con umbrales de desfibrilación elevados en los cuales esto no resulta posible se da inicio a una serie de maniobras tendientes a corregir la situación. En esta presentación se describe un caso en el que se recurrió a una estrategia de uso poco frecuente para mejorar resultados durante la falla del UDF. Se trata de un paciente de 78 años, de sexo masculino, con antecedentes de miocardiopatía dilatada, que fue derivado al laboratorio de electrofisiología para el implante de un CDI para prevención primaria. Durante el procedimiento, el CDI falló en desfibrilar al paciente aun luego de haber posicionado el cable en diferentes áreas del ventrículo derecho y de haber optimizado la onda de choque. El paciente finalmente recibió el implante de un electrodo de desfibrilador en la vena ácigos, lo que permitió la reorientación del vector de desfibrilación hacia el eje posterior, con el resultado de una desfibrilación exitosa de la fibrilación ventricular por el CDI.

The evaluation of the defibrillation threshold (DFT) is common after the implantation of implantable cardioverter defibrillator (ICD) devices. The goal of this standard of care is to achieve successful defibrillation of ventricular fibrillation. In patients with elevated defibrillation thresholds, alternative techniques are required to correct the situation. We describe a case in which an uncommon strategy was used to improve DFT after failed defibrillation. A 78-year old man with a history of dilated cardiomyopathy was referred to the electrophysiology laboratory to have an ICD implanted as primary prevention strategy. During the procedure, the ICD failed to defibrillate the patient even after the lead was placed in different areas of the right ventricle and after optimizing the shock wave. A defibrillation lead was implanted in the azygos vein, and the shock vector was directed towards the posterior axis; a successful defibrillation was thus achieved.