Marco Larobina

Epicardial wave mapping in human long-lasting persistent atrial fibrillation: transient rotational circuits, complex wavefronts, and disorganized activity

OBJECTIVES To characterize the nature of atrial fibrillation (AF) activation in human persistent AF (PerAF) using modern tools including activation, directionality analyses, complex-fractionated electrogram, and spectral information. BACKGROUND The mechanism of PerAF in humans is uncertain. METHODS AND RESULTS High-density epicardial mapping (128 electrodes/6.75 cm(2)) of the posterior LA wall (PLAW), LA and RA appendage (LAA, RAA), and RSPV-LA junction was performed in 18 patients with PerAF undergoing open heart surgery. Continuous 10 s recordings were analysed offline. Activation patterns were characterized into four subtypes (i) wavefronts (broad or multiple), (ii) rotational circuits (≥2 rotations of 360°), (iii) focal sources with centrifugal activation of the entire mapping area, or (iv) disorganized activity [isolated chaotic activation(s) that propagate ≤3 bipoles or activation(s) that occur as isolated beats dissociated from the activation of adjacent bipole sites]. Activation at a total of 36 regions were analysed (14 PLAW, 3 RSPV-LA, 12 LAA, and 7 RAA) creating a database of 2904 activation patterns. In the majority of maps, activation patterns were highly heterogeneous with multiple unstable activation patterns transitioning from one to another during each recording. A mean of 3.8 ± 1.6 activation subtypes was seen per map. The most common patterns seen were multiple wavefronts (56.2 ± 32%) and disorganized activity (24.2 ± 30.3%). Only 2 of 36 maps (5.5%) showed a single stable activation pattern throughout the 10-s period. These were stable planar wavefronts. Three transient rotational circuits were observed. Two of the transient circuits were located in the posterior left atrium, while the third was located on the anterior surface of the LAA. Focal activations accounted for 11.3 ± 14.2% of activations and were all short-lived (≤2 beats), with no site demonstrating sustained focal activity. CONCLUSION Human long-lasting PerAF is characterized by heterogeneous and unstable patterns of activation including wavefronts, transient rotational circuits, and disorganized activity.

The Ross procedure using autologous support of the pulmonary autograft: techniques and late results

OBJECTIVES It is hypothesized that by performing radical aortic root manipulation and then autologous support for the pulmonary autograft in the Ross procedure, this will maintain aortic root size and should, in turn, lead to the demonstrated low incidence of late aortic regurgitation and need for reoperation on the aortic root and valve. METHODS Aortic root size was measured echocardiographically both preoperatively and then at second yearly intervals in 322 consecutive patients who underwent a Ross operation between October 1992 and June 2013 with autologous support of the pulmonary autograft root using the patients own aorta. This technique, a variant of the inclusion cylinder method, has been developed with the aim of minimizing prosthetic materials in the aortic root. RESULTS Measures to reduce aortic root size included annulus reduction in 201 patients (62.4%) and reduction in aortic sinus or sinotubular junction in 159 patients (49.4%). Maximal aortic root diameter postoperatively at 5, 10, and 15 years was 34.0, 34.6, and 34.7 mm, respectively. Eleven reoperations were required during the study period for progressive aortic regurgitation (none for aortic root enlargement), with freedom from reoperation being 96% at both 15 years and 18 years. Preoperative pure aortic regurgitation, aortic annulus, and sinotubular junction enlargement were risk factors for reoperation. CONCLUSIONS This inclusion method of pulmonary autograft implantation leads to minimal increases in aortic root size over time, with no reoperations for aortic root dilatation and a low requirement for aortic valve reoperation. The Ross procedure deserves to remain on the surgical menu for aortic valve replacement.

Twenty-year analysis of autologous support of the pulmonary autograft in the ross procedure

BACKGROUND The Ross procedure is seldom offered to adults less than 60 years of age who require aortic valve replacement except in a few high-volume centers with documented expertise. Inserting the pulmonary autograft as an unsupported root replacement may lead to increasing reoperations on the aortic valve in the second decade. METHODS Of 333 patients undergoing the Ross procedure between October 1992 and June 2012, the study group of 310 consecutive patients (mean age ± standard deviation, 39.3±12.7 years (limits 16-63) had the aortic root size adjusted to match the pulmonary autograft, which was inserted as a root replacement, with the aorta closed up around it to provide autologous support. RESULTS The mean follow-up time was 9.4 years; the actuarial survival was 97% at 16 years; and freedom from the composite of all reoperations on the aortic valve and late echocardiographic-detected aortic regurgitation greater than mild was 95% at 5 years, 94% at 10 years, and 93% at 15 years. Overall freedom from all reoperations on aortic and pulmonary valves was 97% at 5 years, 94% at 10 years, and 93% at 15 years. All results were better for the patients presenting with predominant aortic stenosis (98% freedom at 15 years) than for those with aortic regurgitation (p=0.01). CONCLUSIONS Autologous support of the pulmonary autograft leads to excellent results in the groups presenting with aortic stenosis and mixed aortic stenosis/regurgitation and to good results for those presenting with pure aortic regurgitation. The Ross procedure, using one of the proven, durable techniques available, should be considered for more widespread adoption.

Acute atrial stretch results in conduction slowing and complex signals at the pulmonary vein to left atrial junction: insights into the mechanism of pulmonary vein arrhythmogenesis

Background—The pulmonary vein–left atrial (PV–LA) junction is key in pathogenesis of AF, and acute stretch is an important stimulus to AF. We aimed to characterize the response of the junction to acute stretch, hypothesizing that stretch would result in electrophysiological changes predisposing to re-entry. Methods and Results—Fifteen participants undergoing cardiac surgery underwent evaluation of the right superior PV–LA junction using an epicardial mapping plaque. In 10, this was performed before and after atrial stretch imposed by rapid volume expansion, and in 5, it was performed with an intervening observation period. Activation was characterized by conduction slowing and electrogram fractionation transversely across the PV–LA junction, with lines of block also demonstrated perpendicular to the junction. Conduction was decremental (plaque activation time 135.8±46.8 ms with programmed extra stimuli at 10 ms above effective refractory period versus 66.1±22.9 ms with pacing at 400 ms; P<0.001) and percentage fractionation was greater with programmed extra stimuli at 10 ms above (33.5%±15.3% versus 20.7%±14.0%, P=0.001). Right atrial pressure increased by 2.5±1.8 mm Hg (P=0.002) with volume expansion. Stretch resulted in conduction slowing across the PV–LA junction (increase in activation time 10.9±14.6 ms in acute stretch group versus −0.1±4.5 ms in control group; P=0.002). Conduction slowing was more marked with programmed extra stimuli at 10 ms above effective refractory period than with stable pacing (13.4±16.5 ms versus 1.7±5.4 ms; P=0.003). Stretch resulted in a significant increase in fractionated electrograms (7.9%±7.0% versus −0.4±3.3; P=0.004). Conclusions—Acute stretch results in conduction slowing across the PV–LA junction, with a greater degree of signal complexity. This substrate may be important in AF initiation and maintenance by promoting re-entry.

Diagnostic enigma: primary pulmonary artery sarcoma

Primary angiosarcoma of pulmonary artery is a very rare lesion. We present a case of primary angiosarcoma that was initially misdiagnosed as a subacute massive pulmonary thromboembolism in a 30-year-old man. This rare disease is usually indistinguishable from acute or chronic thromboembolic disease of the pulmonary arteries. The clinical and radiological findings of pulmonary artery angiosarcoma are similar to those of pulmonary thromboembolism. Although the incidence of pulmonary artery angiosarcoma is very low, our case demonstrates that this disease entity should be included in the differential diagnosis of pulmonary thromboembolism. Patients with early identification can have curative potential with aggressive surgical intervention.

High-density epicardial mapping of the pulmonary vein-left atrial junction in humans: Insights into mechanisms of pulmonary vein arrhythmogenesis

BACKGROUND The pulmonary veins (PVs) and the PV-LA (left atrium) junction are established sources of triggers initiating atrial fibrillation. In addition, they have been implicated in the maintenance of arrhythmia. OBJECTIVE To undertake high-density electrophysiological characterization of the right superior PV-LA junction in humans. METHODS Mapping was performed in 18 patients without a history of atrial fibrillation undergoing cardiac surgery. A high-density epicardial plaque was positioned at the anterior right superior pulmonary vein covering 3 regions: LA, PV-LA junction, and the PV. Isochronal maps were created during (1) sinus rhythm (SR); (2) LA pacing (LA-Pace); (3) PV pacing (PV-Pace); (4) LA programmed electrical stimulation (LA-PES); and (5) PV programmed electrical stimulation (PV-PES). Regional differences in conduction slowing/conduction block (CS/CB) and the prevalence of fractionated signals (FS) and double potentials (DPs) were assessed. RESULTS A region of isochronal crowding representing CS/CB developed at the PV-LA junction in 84% of the maps. Three distinct activation patterns were seen. Pattern 1: Uniform SR activation without CS/CB. LA-Pace and PES caused 1 to 2 lines of isochronal crowding (CS/CB) at the PV-LA junction. Pattern 2: CS/CB occurred at the PV-LA junction in SR. LA/PV-Pace and LA/PV-PES caused an increase in CS/CB at the PV-LA junction with widely split DPs and FS. Pattern 3: A single incomplete line of CS at the PV-LA junction in SR. With LA/PV pacing and LA/PV-PES, multiple lines (≥3) of CS/CB developed at the PV-LA junction with evidence of circuitous activation and a marked increase in DPs and FS. CONCLUSION High-density epicardial mapping of the right superior pulmonary vein demonstrates marked functional conduction delay and circuitous activation patterns at the PV-LA junction, creating the substrate for reentry.

Inclusion cylinder method for aortic valve replacement utilising the Ross operation in adults with predominant aortic stenosis – 99% freedom from re-operation on the aortic valve at 15 years

Background: To report our experience with the Ross operation in patients with predominant aortic stenosis (AS) using an inclusion cylinder (IC) method. Methods: Out of 324 adults undergoing a Ross operation, 204 patients of mean age of 41.3 years (limits 16–62) underwent this procedure for either AS or mixed AS and regurgitation (AS/AR) between October, 1992 and February, 2012, implanting the PA with an IC method. Clinical follow up and serial echo data for this group is 97% complete with late mortality follow up 99% complete. Results: There has been zero (0%) early mortality, and late survival at 15 years is 98% (96%, 100%). Only one re-operation on the aortic valve for progressive aortic regurgitation (AR) has been required with freedom from re-operation on the aortic valve at 15 years being 99% (96%, 100%). The freedom from all re-operations on the aortic and pulmonary valves at 15 years is 97% (94%, 100%). Echo analysis at the most recent study shows that 98% have nil, trivial or mild AR. Aortic root size has remained stable, shown by long-term (15 year) echo follow up. Conclusions: In an experience spanning 19 years, the Ross operation used for predominant AS using the IC method described, results in 99% freedom from re-operation on the aortic valve at 15 years, better than any other tissue or mechanical valve. For adults under 65 years without significant co-morbidities who present with predominant AS, the pulmonary autograft inserted with this technique gives excellent results.

Clinical-pathologic conference in general thoracic surgery: disseminated nocardiosis presenting as Pancoast syndrome

Clinical Summary A 61-year-old woman presented with a left upper lobe lung lesion and clinical evidence of T1 neuropraxia. Her history included carcinoma of the ovary treated with surgical resection and adjuvant chemotherapy with paclitaxel (Taxol) 10 months before presentation. She had a 20 pack-year history of smoking, ceasing 10 years before, and was hospitalized as a child with pneumonia. She had taken only hormone replacement therapy before the diagnosis of the ovarian carcinoma. She had become unwell in January 2001, with generalized lethargy, an intermittent cough, and a reduction in exercise tolerance from several kilometers to several hundred meters. Left shoulder pain extending down her arm preceded the development of some mild weakness of her left thenar eminence. She had had several upper respiratory illnesses in December but had no fevers or sweats, hemoptysis, change in voice, weight loss, or other neurologic symptoms. Chest radiography revealed a mass in the superior pulmonary sulcus (Figure 1), which, on computed tomographic (CT) scanning, was shown to arise from the apex of the left lung and extend into the chest wall (Figure 2). This is highly suggestive of invasive carcinoma. Two percutaneous biopsy specimens were nondiagnostic, showing no malignant cells, occasional granulomata, and no organisms. single photon emission computed tomography (SPECT) scanning showed soft tissue inflammation in the left supraclavicular fossa, with involvement of the first rib. The features were considered nonspecific. Anterior mediastinotomy failed to reveal any evidence of metastatic tumor, and the patient was transferred to our institution for definitive surgical intervention. Registrar, Department of Cardiothoracic Surgery, the Department of Pathology, and the Cardiothoracic Unit, The Alfred, Melbourne, Australia.

The Ross procedure in adults presenting with bicuspid aortic valve and pure aortic regurgitation: 85% freedom from reoperation at 20 years

OBJECTIVES The Ross procedure has demonstrated excellent results when performed in patients with aortic stenosis or mixed aortic valve disease [aortic stenosis and aortic regurgitation (AR)]. However, due to its reported risk of late reoperation, it is not recommended under current guidelines for patients presenting with bicuspid aortic valve and pure AR. We have analysed our own results in light of this recommendation. METHODS Between 1993 and 2016, 129 consecutive patients with a mean age of 34.7 ± 10.6 years (range 16-64 years) presented with bicuspid aortic valve and pure AR and underwent the Ross procedure. Patients were reviewed annually and had 2nd yearly transthoracic echocardiograms during follow-up. The unit had a liberal reoperation policy where reoperation was performed if patients developed recurrent moderate or greater AR during follow-up. RESULTS There was 1 inpatient death, and 3 late deaths over a mean follow-up duration of 9.6 ± 6.8 years. Late survival at 10 and 20 years post-surgery were 99% [95% confidence interval (CI) 94-100] and 95% (95% CI 85-99), respectively. Eleven patients underwent redo aortic valve replacement (AVR) and 4 patients had redo pulmonary valve replacement. Freedom from reoperation for AVR and more-than-mild AR at 10 and 20 years post-surgery were 89% (95% CI 81-94) and 85% (95% CI 74-92), respectively. Having longer aortic cross-clamp (hazard ratio 1.03, 95% CI 1.00-1.06; P = 0.05) and cardiopulmonary bypass times (hazard ratio 1.02, 95% CI 1.00-1.05; P = 0.05), and having a larger preoperative sinotubular junction diameter (hazard ratio 1.15, 95% CI 1.03-1.30; P = 0.02) were significant predictors of having redo AVR or significant AR at follow-up. CONCLUSIONS With a 20-year freedom from redo AVR and greater-than-mild residual AR of 85%, the utilization of the Ross procedure in bicuspid aortic valve patients with pure AR should be considered.

Use of Transcatheter Valves for Open Surgical Mitral Valve Replacement. Australian Experience

BACKGROUND Mitral valve procedures remain a surgical challenge in the presence of extensive annular calcification, which presents a formidable technical challenge. Aggressive debridement is limited by risk of serious complications and the technical complexity of pericardial patch reconstruction of the debrided area. METHODS An open surgical approach with a transcatheter valve allows the valve to be placed under direct visualisation to facilitate positioning and to evaluate the likelihood of both perivalvular leakage and atrioventricular disruption. The open approach has the additional advantage of performing concomitant surgeries like other valve procedures, arrhythmias surgeries and coronary bypass. RESULTS We present our experience with open surgical mitral valve replacement (MVR) using transcatheter valve in different patients requiring varied procedures. These patients were not suitable for MVR using standard prosthetic valve and techniques. They were also not suitable for percutaneous MVR because of heavily calcified anterior mitral leaflet and the other concomitant procedures required. CONCLUSIONS Open MVR with a transcatheter balloon-expandable valve can avoid the need for technically challenging and high-risk decalcification of mitral annulus. These novel techniques using transcatheter valves can be successful in complex cases where standard prosthetic valves are impossible to implant in a heavily calcified mitral annulus.