Single Pulmonary Vein Research Articles

Anomalous Unilateral Single Pulmonary Vein Mimicking Pulmonary Nodules on HRCT of the Lungs and Scimitar Syndrome on Chest Radiograph: Multidetector CT Findings

Anomalous unilateral single pulmonary vein is an extremely rare anomaly of the pulmonary venous system. It is often confused with other pulmonary abnormalities such as hypogenetic lung (scimitar) syndrome, pulmonary varices, pulmonary nodules, and arteriovenous malformations. We present imaging findings including multidetector computerized tomography in a case of anomalous unilateral single pulmonary vein mimicking pulmonary nodules on high-resolution computed tomography of the lungs and scimitar syndrome on chest radiograph in an asthmatic girl.

HYPERTONICITY INCREASES RABBIT ATRIUM AND PULMONARY VEIN ARRHYTHMOGENESIS: A POTENTIAL CONTRIBUTOR TO THE GENESIS OF ATRIAL FIBRILLATION

1. Pulmonary veins are the most important focus for the initiation of atrial fibrillation. Diabetes mellitus may be associated with hypertonicity and increased occurrence of atrial fibrillation. 2. The purpose of the present study was to investigate whether hypertonicity alters the electrophysiological characteristics of pulmonary veins and atria to enhance the genesis of atrial fibrillation. 3. A whole-cell patch-clamp technique was used to investigate action potentials and ionic currents in rabbit isolated single pulmonary vein and atrial cardiomyocytes during immersion in isotonic and hypertonic (1.2x normal osmolality) solutions. 4. Hypertonicity increased the spontaneous beating rates of pulmonary vein cardiomyocytes from 2.3 +/- 0.3 to 3.4 +/- 0.3 Hz (n = 11; P < 0.001). Hypertonicity prolonged action potential duration to a greater extent in atrial cardiomyocytes than in pulmonary vein cardiomyocytes. Compared with atrial cardiomyocytes, hypertonicity increased the transient inward currents and Na(+)/Ca(2+) exchange currents to a greater extent in pulmonary vein cardiomyocytes, but decreased the delayed rectified potassium currents to a lesser extent. 5. Hypertonicity plays an important role in the electrical activity of pulmonary vein and atrial cardiomyocytes, which may have a potential role in the pathophysiology of atrial fibrillation.

Arrhythmogenic Potential of Pulmonary Venous Tissue: Triggers for Atrial Fibrillation Identified within the Remnant of a Vein

Pulmonary veins (PVs) have frequently been identified as triggers for atrial fibrillation (AF), and higher arrhythmogenic potential of superior PVs has been attributed to their larger size, which can more rigorously support abnormalities of impulse formation and/or conduction. Contrary to this belief, we report our observations in a 63-year-old patient with history of lung cancer, S/P left upper lobectomy, undergoing ablation for paroxysmal AF. Circular mapping (Lasso) and ablation (ABL; 8-mm) catheters were deployed in left atrium (LA). Intracardiac ultrasound revealed separate right superior (RS) and inferior (RI) PVs and a single left PV. Segmented LA anatomy from the CT angiogram images corroborated this, although on the latter there appeared to be a "stump" at superior aspect of the left PV. This stump likely was the remnant of the left superior (LS) PV. Thus, the patent left vein was likely the dilated left inferior (LI) PV. With the Lasso and ABL deployed at the LIPV ostium and LSPV remnant, respectively, AF was reproducibly seen to initiate with earliest activity in the latter. Single radio-frequency ablation (RFA) lesion within the LSPV remnant abolished AF triggers. Additional RFA was done to isolate LI, RS, and RI PVs. Over a follow-up period of 24 months, this patient has remained free from AF off any drugs. Our observations suggest that even very proximal remnants of PVs can serve as triggers for AF. Recognition of this phenomenon was facilitated by the use of advanced imaging technique and the deployment of multiple catheters.

Anomalous Midline Common Ostium of the Left and Right Inferior Pulmonary Veins

A 41-year-old man with a history of paroxysmal symptomatic atrial fibrillation refractory to antiarrhythmic drug therapy was referred for pulmonary vein (PV) isolation. Before the procedure, he underwent standard cardiac computed tomographic angiography to evaluate left atrium and PV anatomy, which revealed single right and left superior PVs, each with a moderate-sized ostium. However, the right and left inferior PVs originated from a common and unusually large ostium in the midpostero-inferior left atrium (Figure). Using a double trans-septal approach, an 8-mm tip deflectable ablation catheter and a 20-pole LASSO catheter were inserted …

An Unusual Case of Postoperative Hypoxemia Diagnosed with Transesophageal Echocardiography

An Unusual Case of Postoperative Hypoxemia Diagnosed with Transesophageal Echocardiography

Pneumonectomy in scimitar syndrome —is it correct?

The scimitar syndrome is a rare congenital anomaly that is characterized by anomalous pulmonary venous drainage to the inferior vena cava causing a left-to-right shunt. Because the radiographic shadow of the anomalous vein resembles a curved turkish saber, this defect has been called as the “scimitar deformity”1. Here we present a two months old male child with an anomalous drainage of the single right pulmonary vein draining the entire right lung into the inferior vena cava, direct arterial supply from the abdominal aorta to the right lung, horse-shoe lung and unilobar hypoplastic right lung. The child was treated surgically with a right pneumonectomy. The child had an uneventful postoperative recovery.

Endothelin‐1 Modulates the Arrhythmogenic Activity of Pulmonary Veins

Endothelin-1 has important cardiovascular effects and is activated during atrial fibrillation. Pulmonary veins (PVs) play a critical role in the pathophysiology of atrial fibrillation. The aim of this study was to evaluate whether endothelin-1 affects PV arrhythmogenic activity. Conventional microelectrodes were used to record the action potentials (APs) and contractility in isolated rabbit PV tissue specimens before and after the administration of endothelin-1 (0.1, 1, 10 nM). The ionic currents of isolated PV cardiomyocytes were investigated before and after the administration of endothelin-1 (10 nM) through whole-cell patch clamps. In the tissue preparation, endothelin-1 (1, 10 nM) concentration dependently shortened the AP duration and decreased the PV firing rates. Endothelin-1 (10 nM) decreased the resting membrane potential. Endothelin-1 (0.1, 1, 10 nM) decreased the contractility and increased the resting diastolic tension. In single PV cardiomyocytes, endothelin-1 (10 nM) decreased the PV firing rates from 2.7 +/- 1.0 Hz to 0.8 +/- 0.5 Hz (n = 16). BQ-485 (100 microM, endothelin-1 type A receptor blocker) reversed and prevented the chrono-inhibitory effects of endothelin-1 (10 nM). Endothelin-1 (10 nM) reduced the L-type calcium currents, transient outward currents, delayed rectifier currents, transient inward currents, and sodium-calcium exchanger currents in the PV cardiomyocytes with and without pacemaker activity. Endothelin-1 (10 nM) increased the inward rectifier potassium current, hyperpolarization-induced pacemaker current, and the sustained outward potassium current in PV cardiomyocytes with and without pacemaker activity. Endothelin-1 may have an antiarrhythmic potential through its direct electrophysiological effects on the PV cardiomyocytes and its action on multiple ionic currents.

Swelling activated chloride currents in the electrical activity of pulmonary vein cardiomyocytes

Pulmonary veins (PVs) contain cardiomyocytes with a high arrhythmogenicity for inducing atrial fibrillation. The swelling-activated outwardly rectifying Cl(-) currents (I(Cl,swell)) are important in the electrical activity of cardiomyocytes. This study was to investigate whether I(Cl,swell) play a role in the PV electrophysiological characteristics. A whole-cell patch clamp was used to investigate the action potentials and I(Cl,swell) in isolated rabbit single PV and atrial cardiomyocytes during immersion in isotonic (290-300 mosm L(-1)) and hypotonic (220-230 mosm L(-1)) solutions. The cell length and cell width were measured using confocal microscopy. Hypotonic solution induced larger I(Cl,swell) in the PV cardiomyocytes with pacemaker activity than those in the PV cardiomyocytes without pacemaker activity or atrial cardiomyocytes. Hypotonic solution shortened the action potential duration and increased the cell width to a greater extent in the PV cardiomyocytes than in the atrial cardiomyocytes. Moreover, hypotonic solution decreased the PV firing with a decrease in the transient inward currents and delayed after depolarizations. These findings suggest that the I(Cl,swell) plays an important role in the electrical activity of the PV cardiomyocytes.

Abstract 2544: Pulmonary Venous Anatomy Predicts Recurrent Arrhythmia after Pulmonary Vein Antrum Isolation for Atrial Fibrillation

Background: Pulmonary Vein Antrum Isolation (PVAI) is being used with increasing frequency for the treatment of atrial fibrillation. Multi-detector computed tomography (MDCT) can be used to evaluate the complex anatomy of the left atrium and pulmonary veins to facilitate PVAI. We hypothesized that pulmonary vein anatomy, as determined by MDCT, would predict recurrent atrial fibrillation after PVAI. Methods: We evaluated consecutive patients scheduled for PVAI who underwent a CT examination of the pulmonary veins on a Philips Brilliance 64 or Siemens Sensation-64 slice MDCT scanner &lt; 3 months prior to a PVAI procedure. The number and ostial area of all pulmonary veins, indexed to body surface area, were determined by 2 independent blinded observers. Transtelephonic monitoring was performed for the first 3– 6 months after the PVAI procedure. Patients were followed at 3, 6, and 12 months with a 12-lead EKG and 48-hour Holter monitor. Results: A total of 113 patients (mean age 58±10 years; 73% male) were enrolled and followed for 12 months. A total of 445 pulmonary vein ostia were analyzed; 26% of patients had left sided pulmonary veins with a shared common ostium. The remaining patients had 2 separate left sided pulmonary veins. At the end of the 12-month follow-up, patients with two left sided pulmonary veins had a significantly increased risk of recurrent arrhythmia (34.3%) after PVAI than patients with a common left pulmonary vein (7.7%; p=0.009; OR 4.45). There was no relationship between the number of right sided pulmonary veins or total pulmonary vein ostial size and recurrent arrhythmia (582 cm 2 /m 2 in patients with recurrence vs 505 cm 2 /m 2 without recurrence (P= 0.14). Conclusion: In patients undergoing PVAI for atrial fibrillation, the presence of two left sided pulmonary veins, as determined by MDCT, is associated with an increased risk of recurrent arrhythmia at 12 months compared with patients who have a single common left pulmonary vein.

Difference between electrical remodelling after pulmonary veins and right atrium appendage pacing

Pulmonary veins (PVs) are important sources of paroxysmal atrial fibrillation (AF). Rapid atrial pacing changes atrial electrophysiology, and facilitates the induction and maintenance of AF. The purpose of our study was to evaluate the changes in atrial effective refractory period (AERP) proprieties and in ionic currents in PVs myocytes from dogs subjected to rapid atrial pacing in PVs and right atrial appendage (RAA) and to relate these changes to the ability to induce AF. Twelve mongrel dogs in normal sinus rhythm were paced from the superior left PVs or RAA at 500 bpm for 4 h. Electrophysiological studies were conducted to determine the changes in AERP, dispersion, and rhythm. Ionic currents were evaluated using patch clamp technique in single PVs myocytes in sham-operated dogs, and the results were compared with those from PVs and RAA pacing groups. The presence of rapid atrial pacing was associated with a marked shortening in AERP in both PVs and RAA pacing group with a marked increase in AERP dispersion in PVs pacing. Both L-type calcium current (I(Ca,L)) and the transient outward current (I(to)) were reduced in both groups with an increased significance in PVs pacing group. The density of I(Ca,L) was decreased significantly from (-6.03 +/- 0.63) pA/pF in the control group to (-3.21 +/- 0.34) pA/pF in the PVs pacing group and (-4.75 +/- 0.41) pA/pF in the RAA pacing group (n = 6, P < 0.05), whereas the density of I(to) was decreased significantly from (8.45 +/- 0.71) pA/pF in the control group to (5.21 +/- 0.763) pA/pF in the PVs pacing group and (6.84 +/- 0.69) pA/pF in the RAA pacing group (n = 6, P < 0.05). Our findings provide likely ionic mechanisms of shortened repolarization in induced atrial tachycardia with a decrease in I(Ca,L) and I(to) densities, which is the likely mechanism for a decrease in action potential duration rate adaptation in the canine rapid pacing model more pronounced in the PVs pacing group underlying the crucial role of PVs in initiating AF.

CT Radiographic Findings

Radio-frequency catheter ablation (RFCA) is an ever increasing modality for treating refractory atrial fibrillation. Radiologists should not only be able to interpret and convey anatomic variations of pulmonary veins and left atrium to referring electrophysiologists, but also should be aware of all the post-RFCA complications and their radiographic findings including this rare, but often fatal complication. This report describes a fatal atrio-esophageal fistula (AEF) involving a normal variant single left common pulmonary vein after transcatheter ablation. A 59-year-old man who presented to the Emergency Department (ED) with altered mental status previously complaining of fatigue and malaise. The patient underwent a total of 2 uneventful circumferential percutaneous pulmonary vein ablations for atrial fibrillation. The most recent was performed 5 weeks before admission to ED. Within hours of initial evaluation, the patient quickly deteriorated owing to overwhelming sepsis requiring both inotropic and ventilatory support. Transthoracic echocardiography within ED showed no evidence of valvular vegetation or gas bubbles in the left atrium. Computed tomography (CT) of the chest with intravenous contrast revealed findings compatible with AEF. Head CT was negative for ischemic changes or emboli. Patient underwent emergent cardiac and esophageal surgery at which point the patient later died on the operating table. Patients who present with signs and symptoms of endocarditis, and particularly with new neurologic symptom after RFCA should be promptly evaluated for AEF. In our case, radiographic findings in correlation with clinical history and high suspicion strongly suggested this rare, often fatal complication. During review of the chest CT, particular vigilance should be made to the left pulmonary vein/posterior left atrium junction at which site fistulous tracts tend to occur. Prompt diagnosis necessitates emergent cardiac and esophageal surgery to prevent rapid deterioration and death.

Tumor necrosis factor-α alters calcium handling and increases arrhythmogenesis of pulmonary vein cardiomyocytes

Inflammation and abnormal calcium homeostasis play important roles in atrial fibrillation. Tumor necrosis factor-α (TNFα), a proinflammatory cytokine, can induce cardiac arrhythmias. Pulmonary veins (PVs) are critical in initiating paroxysmal atrial fibrillation. This study was designed to investigate whether TNFα may change the calcium handling and arrhythmogenic activity of PV cardiomyocytes. We used whole-cell patch clamp and indo-1 fluorimetric ratio technique to investigate the action potentials, ionic currents and intracellular calcium in isolated rabbit single PV cardiomyocytes with and without (control) incubation with TNFα (25 ng/ml) for 7–10 h. The expression of sarcoplasmic reticulum ATPase in the control and TNFα-treated PV cardiomyocytes was evaluated by confocal micrographs and Western blot. We found that the spontaneous beating rates were similar between the control ( n = 45) and TNFα-treated ( n = 28) PV cardiomyocytes. Compared with the control PV cardiomyocytes, the TNFα-treated PV cardiomyocytes had significantly a larger amplitude of the delayed afterdepolarizations (6.0 ± 1.7 vs. 2.6 ± 0.8 mV, P < 0.05), smaller L-type calcium currents, larger transient inward currents, larger Na +–Ca 2+ exchanger currents, a smaller intracellular calcium transient, smaller sarcoplasmic reticulum calcium content, larger diastolic intracellular calcium, a longer decay portion of the calcium transient (Tau), and a decreased sarcoplasmic reticulum ATPase expression. In conclusion, TNFα can increase the PV arrhythmogenicity and induce an abnormal calcium homeostasis, thereby causing inflammation-related atrial fibrillation.

Normative Analysis of Pulmonary Vein Drainage Patterns on Multidetector CT With Measurements of Pulmonary Vein Ostial Diameter and Distance to First Bifurcation

To document the frequency of normal and anomalous drainage patterns of the pulmonary veins, and to establish normal values for pulmonary vein ostial diameters, and distance to first bifurcation using multidetector computed tomography, as pertinent to ablation procedures for atrial fibrillation. Two cardiothoracic radiologists retrospectively reviewed thin-section contrast material-enhanced multidetector computed tomography examinations of the thorax in 200 consecutive patients (38 females and 162 males), age 24-79 years (mean 52.8) referred for imaging before radiofrequency ablation therapy for atrial fibrillation. Pulmonary vein anatomy was based on both the number of venous ostia and the drainage patterns of pulmonary veins. Pulmonary vein ostial diameters and distance to first bifurcation of the four major pulmonary veins (right inferior and superior, left inferior and superior) and any additional pulmonary veins were measured at a workstation using both axial images and multiplanar reconstructions by two experienced cardiothoracic radiologists; the mean pulmonary vein diameter and the shortest distance to first bifurcation of the two measurements are reported. The majority of patients, 82% (164 patients) had four pulmonary veins, with a superior and inferior ostium on the right and a superior and inferior ostium on the left. Of the remainder, 9% (18 patients) had five veins, 4.5% (9 patients) had three veins, 3% (6 patients) had two anomalies each, and 0.5% (1 patient) had three anomalies. The middle lobe pulmonary vein drained into the right superior pulmonary vein in 83.5% of patients, directly into the left atrium in 11% of patients, and into the right inferior pulmonary vein in 5.5% of patients; 6.5% of patients had a single left pulmonary vein ostium. Mean pulmonary vein diameters with 95% confidence intervals at the ostia were as follows: right superior 17.6 (13.64-15.36) mm; left superior 16.6 (16.03-17.08) mm; right inferior 17.1 (16.58-17.55) mm; left inferior 14.8 (14.25-15.27) mm, and independent middle lobe 8.6 (8.27-8.86) mm. Mean distance to first bifurcation with 95% confidence intervals were: right superior 14.5 (17.02-18.23) mm; left superior 17.6 (16.63-18.53) mm; right inferior 7.0 (6.49-7.46) mm; left inferior 13.5 (12.83-14.16) mm, and independent middle lobe 8.4 (7.7-9.17) mm. Thin-section thoracic computed tomography demonstrates a greater variability of pulmonary venous drainage than previously described. There is greater variability of the right lung venous drainage compared to the left lung. Eighty-two percent of people have four standard pulmonary veins. There is significant variability in pulmonary vein diameter and distance to first bifurcation.

A Single Pulmonary Vein as Electrophysiological Substrate of Paroxysmal Atrial Fibrillation

It has been demonstrated that pulmonary veins (PVs) play an important role in initiation and maintenance of paroxysmal atrial fibrillation (AF). However, it is not clearly known whether a single PV acts as electrophysiological substrate for paroxysmal AF. This study included five patients with paroxysmal AF. All patients underwent complete PV isolation with continuous circular lesions (CCLs) around the ipsilateral PVs guided by a three-dimensional mapping system. Irrigated radiofrequency (RF) delivery was performed during AF on the right-sided CCLs in two patients and on the left-sided CCLs in three patients. The incomplete CCLs resulted in a change from AF to atrial tachycardia (AT), which presented with an identical atrial activation sequence and P wave morphology. Complete CCLs resulted in AF termination with persistent PV tachyarrhythmias within the isolated PV in all five patients. PV tachyarrhythmia within the isolated PV was PV fibrillation from the left common PV (LCPV) in two patients, PV tachycardia from the right superior PV (RSPV) in two patients, and from the left superior PV in one patient. All sustained PV tachyarrhythmias persisted for more than 30 minutes, needed external cardioversion for termination in four patients and a focal ablation in one patient. After the initial procedure, an AT from the RSPV occurred in a patient with PV fibrillation within the LCPV, and was successfully ablated. In patients with paroxysmal AF, sustained PV tachyarrhythmias from a single PV can perpetuate AF. Complete isolation of all PV may provide good clinical outcome during long-term follow-up.

Predictors of early recurrence and delayed cure after segmental pulmonary vein isolation for paroxysmal atrial fibrillation without structural heart disease

Early recurrence of atrial fibrillation (ERAF) and delayed cure are commonly observed after atrial fibrillation (AF) ablation. The purpose of this study was to determine the predictors of ERAF and delayed cure after a single pulmonary vein isolation (PVI) performed in paroxysmal AF patients without structural heart disease. In 108 consecutive patients (93 men, 15 women; mean age 51 +/- 8 years) with paroxysmal AF and no structural heart disease, segmental PVI guided by a Lasso catheter was performed. Forty-one percent (44/108) AF patients had ERAF after a single PVI. Univariate analysis revealed that left atrial diameter (p = 0.004), age (p = 0.024) and P-wave dispersion (p = 0.045) were significantly related to ERAF. Logistic regression analysis revealed that left atrial enlargement was the only independent predictor of ERAF (odds ratio [OR] 1.17; 95% confidence interval [CI] 1.04-1.30, p = 0.006). Delayed cure occurred in 32% (14/44) patients with ERAF. P-wave dispersion (p = 0.001), left atrial diameter (p = 0.008) were significantly related to delayed cure. P-wave dispersion was the only independent predictive factor of delayed cure (OR 0.91; 95% CI 0.85-0.97, p = 0.004). Elderly patients with left atrial enlargement and a high dispersion of P wave are susceptible to ERAF after a single PVI. Left atrial enlargement is the only independent predictor of ERAF. Among patients with ERAF, those with less P-wave dispersion and less left atrial diameter have a higher probability of delayed cure. P-wave dispersion can independently predict delayed cure.

Recurrence of pulmonary vein conduction and atrial fibrillation after pulmonary vein isolation for atrial fibrillation: A randomized trial of the ostial versus the extraostial ablation strategy

Both segmental ostial and circumferential extraostial pulmonary vein (PV) isolation have been proven effective in the treatment of atrial fibrillation (AF). However, the recurrence of AF and PV conduction after the 2 ablation strategies has never been compared in a randomized study. A total of 100 consecutive patients (age 56 +/- 10; 71 men) with symptomatic AF (paroxysmal, 51; persistent, 49) were randomized to segmental ostial (n = 54) or circumferential extraostial (n = 46) PV isolation. A circular catheter positioned at the ostium of each target PV guided the ostial PV isolation. Extraostial PV isolation was performed by encircling the paired left and right PVs, respectively, guided by an electroanatomic mapping system. A total of 84% of the patients had recurrent AF after the first PV isolation procedure, showing 72% with AF and 12% with organized left atrial tachycardia. In patients undergoing reablation, all but 2 patients had recurrence of left atrium PV conduction (>95%). During a mean follow-up of 12 months without antiarrhythmic medication, 57% of patients who underwent extraostial PV isolation were free of arrhythmia symptoms compared with 31% of patients who underwent ostial PV isolation (P < .05). This difference in success rate between the 2 ablation strategies was mainly seen in patients known with persistent AF (52% and 15%, respectively; P = .02) as opposed to patients with paroxysmal AF (65% and 46%, respectively; P = .26). Overall, the more proximal, extraostial PV isolation was found to be superior to ostial PV isolation, especially in patients known with persistent AF. A high recurrence rate of 84% after a single complete PV isolation procedure was seen. At reablation, more than 95% had recurrence of left atrium PV conduction regardless of the procedure used, supporting the idea that complete PV isolation seems essential to prevent arrhythmia recurrences.

16-MDCT and MR Angiography of Accessory Diaphragm

1All authors: Department of Radiology, Hospital de Sant Pau, Universidad Autonoma de Barcelona, S. Antoni M Cret 167, 08025 Barcelona, Spain. Address correspondence to A. Hildago (jhidalgop@hsp.santpau.es). e describe an unusual accessory diaphragm, also known as diaphragmatic duplication, identified on chest radiography, contrast-enhanced MDCT, and MR angiography (MRA). In this case, the malformation was associated with a unilateral single pulmonary vein. There are few reported cases of this rare pulmonary malformation, which is sometimes confused with lobar atelectasis and residual changes secondary to pulmonary infections. However, the specific radiologic findings allow a correct diagnosis.

Physiology of Isolated Anomalous Pulmonary Venous Connection of a Single Pulmonary Vein as Determined by Cardiac Magnetic Resonance Imaging

The physiology of isolated partially anomalous pulmonary venous connection of a single pulmonary vein has yet to be fully characterized. This study assessed the magnitude of the left-to-right shunt and right ventricular (RV) dilation from a single anomalous pulmonary vein using cardiac magnetic resonance imaging. Subjects with >1 anomalous pulmonary vein or associated lesions, including atrial septal defects, were excluded. In the 6 subjects identified, the median pulmonary-to-systemic flow ratio was 1.55 (range 1.3 to 1.6). The mean RV end-diastolic volume indexed to body surface area in the subjects was significantly larger than in a normal reference cohort (108 +/- 16 vs 78 +/- 18 cm(3)/m(2), p = 0.0009) and greater than the upper limit of normal in all 6 subjects. Older age did not correlate with increased magnitude of shunting (r = 0.3, p = 0.5), but increased age did correlate with RV end-diastolic volume indexed to body surface area (r = 0.96, p = 0.01). Isolated partially anomalous pulmonary venous connection with only 1 vein connecting anomalously results in a modest left-to-right shunt and mild RV dilation.

Anomalous unilateral single pulmonary vein: Two cases mimicking arteriovenous malformations and a review of the literature

Total anomalous pulmonary venous drainage is a rare congenital anomaly. It usually involves a pulmonary to systemic venous shunt and most cases have a septal defect in order to survive. Anomalous pulmonary venous drainage with pulmonary venous shunting is an extremely rare and entirely benign entity. We present two such cases, in which there was atresia of the left superior pulmonary vein and drainage via a tortuous collateral vein to the left inferior pulmonary vein. This collateral was mistaken on plain film and CT for a pulmonary arteriovenous malformation. Awareness of this anomalous unilateral single pulmonary vein and its radiological appearances may help in avoiding unnecessary pulmonary angiography.

Autonomically Induced Conversion of Pulmonary Vein Focal Firing Into Atrial Fibrillation

This study was designed to determine the mechanism(s) whereby focal firing from pulmonary veins (PVs) is converted into atrial fibrillation (AF). The mechanism(s) whereby PV focal firing or even a single PV depolarization is converted into AF is unknown. In 14 anesthetized dogs a right thoracotomy was performed to expose the right superior pulmonary vein (RSPV). An octapolar electrode catheter was sutured alongside the RSPV so that the distal electrode pair was adjacent to the fat pad containing autonomic ganglia (AG) at the veno-left atrial (LA) junction. An acrylic plaque electrode on the fat pad allowed AG stimulation at voltages ranging from 0.6 to 4.0 V. Multi-electrode catheters were sutured to the atria with their distal electrode pairs at the fat pad-atrial junctions. Right superior pulmonary vein focal firing consisted of S(1)-S(1) = 330 ms followed by as many as 11 atrial premature depolarizations (APDs) (A(2)-A(12)) whose coupling interval just exceeded RSPV refractoriness. Autonomic ganglia stimulation, without atrial excitation, caused a reduction in heart rate (HR): control 142 +/- 15/min, 4.0 V; 75 +/- 30/min, p </=0.05. The fewest number of APDs from the RSPV required to induce AF during AG stimulation was as follows: control (no stimulation) 7 +/- 4, 2.4 V; 3 +/- 1, p </=0.05. In seven dogs, lidocaine (2%, 0.4 cc), a neuronal blocker, was injected into the fat pad, resulting in the loss of AF inducibility in six of seven dogs at the same AG stimulation levels. Three of seven dogs showed AF inducibility only with AG stimulation >/=9.3 V. The effects of AG stimulation at the base of the RSPV can provide a substrate for the conversion of PV firing into AF.