Quantification of low-gradient severe aortic stenosis using a hybrid approach combining Doppler echocardiography and thermodilution.

BACKGROUND AND AIM OF THE STUDY: Estimation of stroke volume in the left ventricular outflow tract (LVOT) is a main limitation to aortic valve area (AVA) calculation by echocardiography when using the continuity equation. In this study, the hypothesis was tested that a hybrid method using thermodilution-derived cardiac output measurement and simultaneous Doppler estimation of the systolic ejection period and transvalvular aortic velocities could be used to accurately assess AVA in patients with low-gradient severe aortic stenosis (AS). METHODS: Eighteen patients with low mean gradient (< 40 mmHg) and nine patients with conventionally defined (> or = 40 mmHg) severe AS (< 1 cm2), as assessed by the echocardiographic continuity equation (baseline echocardiography), underwent catheterization and simultaneous Doppler recording of trans-aortic velocities. RESULTS: The mean pressure gradient was slightly lower by Doppler in the catheterization laboratory (35.8 +/-15.7 mmHg) compared to baseline echocardiography (37.4 +/- 15.2 mmHg) and invasive (38.5 +/- 16.6 mmHg) measurements (both p < 0.05). The AVA values were 0.72 +/- 0.12 cm2 during baseline echocardiography, 0.74 +/- 0.14 cm2 by catheterization, and 0.71 +/- 0.14 cm2 by the hybrid method (bias -0.01 +/- 0.11 cm2 and -0.02 +/- 0.08 cm2, versus echocardiography and catheterization, respectively; both p = NS). CONCLUSION: The hybrid method is reasonably accurate in assessing AVA in patients with low-gradient severe AS. Although the continuity equation should be used in routine clinical practice in most patients, this method could serve as an alternative when the LVOT diameter and/or velocities seem questionable.

Acquired coronary fistula after left ventricular de-airing by apical needle aspiration.

Acquired coronary fistula is uncommon, but has been reported to occur after several surgical procedures, acute myocardial infarction, endomyocardial biopsy, coronary angioplasty, and thoracic trauma. We describe the occurrence of a left coronary to left ventricular cavity fistula following resection of a left atrial myxoma, with spontaneous closure in the following weeks. The fistula was likely caused by a needle inserted into the left ventricular apex, a procedure routinely used to ensure left ventricular de-airing.

Atrial septostomy decreases sympathetic overactivity in pulmonary arterial hypertension.

BACKGROUND: We have reported previously that the sympathetic nervous system is activated in patients with pulmonary arterial hypertension (PAH), and that this is only partly explained by a decrease in arterial oxygenation. Possible causes for increased muscle sympathetic nerve activity (MSNA) in patients with PAH include right atrial distension and decreased cardiac output. Both may be improved by atrial septostomy, but this intervention also further decreases arterial oxygenation. In the present study, we wanted to investigate the effect of atrial septostomy on MSNA in patients with PAH. METHODS: We recorded BP, heart rate (HR), arterial O2 saturation (SaO2), and MSNA before and after atrial septostomy in PAH patients (mean [+/- SE] age, 48 +/- 5 years) and in closely matched control subjects. Measurements were also performed after septostomy, while SaO2 was brought to the preprocedure level by supplemental O2 therapy. RESULTS: Compared to the control subjects (n = 10), the PAH patients (n = 11) had a lower mean BP (75 +/- 2 vs 96 +/- 3 mm Hg, respectively; p < 0.001), lower mean SaO2 (92 +/- 1% vs 97 +/- 0%, respectively; p < 0.001), increased mean HR (84 +/- 4 vs 68 +/- 3 beats/min; p < 0.01), and markedly increased mean MSNA (76 +/- 5 vs 29 +/- 2 bursts per minute; p < 0.001). Atrial septostomy decreased mean SaO2 (to 85 +/- 2%; p < 0.001) and mean MSNA (to 69 +/- 4 bursts per minute; p < 0.01), but did not affect HR or BP. Therapy with supplemental O2 did not affect MSNA, BP, or HR. The decrease in MSNA was correlated to the decrease in right atrial pressure (r = 0.62; p < 0.05). CONCLUSIONS: Atrial septostomy in PAH patients decreases sympathetic hyperactivity despite an associated decrease in arterial oxygenation, and this appears to be related to decreased right atrial distension.

Robotic-enhanced biventricular resynchronization: an alternative to endovenous cardiac resynchronization therapy in chronic heart failure.

BACKGROUND: Cardiac resynchronization therapy (CRT) by pacing the left and right ventricles is an emerging option for treatment of severe heart failure with ventricular conduction disturbances. Stimulation through a coronary vein is currently the technique of choice to achieve left ventricular (LV) pacing. Unfortunately, this approach carries significant limitations and drawbacks. Therefore we explored robotic-enhanced thoracoscopic implantation of an epicardial lead as an alternative technique to stimulate the LV in cardiac resynchronization therapy. METHODS: A total of 15 patients were included in this study. Right (atrial and ventricular) leads were implanted classically through the left subclavian vein. Robotic-enhanced thoracoscopy was then performed to implant the LV epicardial lead. RESULTS: Of the 15 patients, 13 underwent successful endoscopic robotic cardiac resynchronization therapy. Two patients underwent conversion to a small thoracotomy. No perioperative complication occurred in the patients who did not undergo conversion. Acute and chronic LV lead thresholds were satisfactory in all patients, improving over time. All were subjectively and objectively improved at 4 months. As compared with conventional methods, the procedural cost was not significantly affected. CONCLUSIONS: Based on this feasibility study, we believe that robotic LV epicardial lead implantation is a valuable option to achieve biventricular resynchronization therapy. It allows for more reproducible acute thresholds for LV pacing and sensing than does the percutaneous approach; enables fine tuning of the LV lead position, thus potentially providing optimal hemodynamic benefit; and avoids the pitfalls and limitations of the endovenous approach. Therefore it deserves further prospective studies to assess its place in the therapeutic armamentarium against heart failure.

Recurrent transient ischemic attacks in a patient with intrapulmonary arteriovenous shunting detected after closure of a patent foramen ovale.

Paradoxical embolism through right-to-left shunts is widely accepted as a potential cause of cerebral ischemia. Contrast echocardiography is an excellent tool for detection of these shunts. The timing of the appearance of bubbles in the left atrium (ie, early vs late) allows differentiation of foramen ovale patency from intrapulmonary shunting as a result of arteriovenous malformations. We report a patient with recurrent neurologic deficit after surgical closure of a patent foramen ovale. Transesophageal echocardiography demonstrated residual right-to-left shunting from previously unrecognized pulmonary arteriovenous malformations associated with hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu). This case illustrates the fact that contrast echocardiography may fail to identify intrapulmonary shunts when a resting patent foramen ovale coexists.

Pulmonary vein isolation by robotic-enhanced thoracoscopy for symptomatic paroxysmal atrial fibrillation.

BACKGROUND: Pulmonary vein isolation (PVI) has been shown to be effective treatment of patients with symptomatic paroxysmal atrial fibrillation (PAF). The percutaneous approach is currently the technique of choice. Unfortunately, this procedure has limitations and complications that lead to fluctuating success rates. We explored an alternative technique of robotic-enhanced, closed-chest PVI with an endoscopic microwave-based catheter. METHODS: Seven symptomatic PAF patients were included in the study. The pulmonary veins were isolated through right (only) robotic-enhanced thoracoscopy on the beating heart. RESULTS: Six patients underwent successful endoscopic PVI. In 1 patient the operation was converted into small right thoracotomy. Operative assessment of the ablation line showed a successful electric block in every patient. Three months after the procedure, the first 5 patients were in permanent sinus rhythm. The 2 other patients had AF but had less frequent and less symptomatic episodes compared with the preoperative situation. CONCLUSIONS: On the basis of this preliminary experience, we believe that in the near future endoscopic right-chest robotic-enhanced PVI on the beating heart may become a valid option in the treatment of symptomatic PAF patients. This procedure allows for more-reproducible ablation lines and may avoid many of the pitfalls and drawbacks of the percutaneous approach. Therefore this technique deserves larger prospective evaluation in the treatment of AF.

Myocardial homing of nonmobilized peripheral-blood CD34+ cells after intracoronary injection.

Granulocyte--colony-stimulating factor administered for autologous hematopoietic stem cell isolation from blood may favor restenosis in patients implanted after acute myocardial infarction (AMI). We therefore tested the isolation of peripheral-blood CD34+ cells without mobilization in six patients with AMI. After large-volume cytapheresis and positive CD34+ cell selection, 3.6 to 27.6 million CD34+ cells were obtained. We performed intra-coronary implantation of these cells and recorded no restenosis or arrhythmia. We used positron emission tomography (PET) to assess myocardial-labeled CD34+ cell homing, which accounted for 5.5% of injected cells 1 hour after implantation. In conclusion, large amounts of CD34+ cells, in the range reported in previous studies, can be obtained from nonmobilized peripheral blood. PET with [18F]-fluorodeoxyglucose cell labeling is an efficient imaging method for homing assessment.

Effects of right ventricular pacing on regional myocardial glucose metabolism.

AIMS: Permanent right ventricular apical pacing (RVP) is associated with a wide range of myocardial abnormalities. The purpose of this study was to determine the changes over time of RVP on myocardial blood flow (MBF) and glucose metabolism as assessed by positron emission tomography (PET). METHODS: In eight candidates for permanent pacemaker implantation PET imaging was performed with 13N-ammonia and 18F-Fluorodeoxyglucose (FDG) to assess MBF and glucose metabolism before (PET1) and repeated after 3 months of RVP (PET2). For the analysis, the left ventricle was divided into three parts (apex, mid-ventricular and base) and subdivided into six segments (inferior, posterior, lateral, anterior, antero-septal and infero-septal). RESULTS: After RVP, defects of FDG uptake were found in the left ventricle near the stimulation site, without corresponding changes in MBF. Changes over time in the mean FDG uptake were statistically significant between PET1 and PET2 in the apical inferior, apical-posterior, apical-anterior, apical antero-septal, apical infero-septal, mid-inferior and mid-infero-septal segments. CONCLUSIONS: This study shows that RVP induces major changes in the distribution of FDG uptake in the left ventricular myocardium. FDG uptake significantly decreases in the regions surrounding the pacing site.

Sympathetic nerve activity after thoracoscopic cardiac resynchronization therapy in congestive heart failure.

BACKGROUND: Sympathetic benefits of thoracoscopic cardiac resynchronization therapy (TCRT) in congestive heart failure (CHF) are unknown. We determined cardiac hemodynamics, functional status, and muscle sympathetic nerve activity (MSNA) in a group of TCRT patients. We aimed to compare these patients with CHF patients with cardiac asynchrony (ASY) to substantiate the beneficial effects of TCRT. METHODS AND RESULTS: Eleven patients resynchronized by TCRT 6 +/- 1 months before study inclusion (SYN) and 10 matched ASY patients underwent blood pressure, heart rate, and MSNA recordings. All underwent functional status, cardiac index, and left ventricular ejection fraction (LVEF) assessments. SYN patients had shorter QRS duration and interventricular mechanical delays, longer 6 minute walking distance and lower New York Heart Association class (all P < .05) than ASY patients. MSNA of 56 +/- 2 bursts/min in ASY patients was higher than in SYN patients (48 +/- 3 bursts/min, P < .05). Cardiac index was higher in SYN patients than in ASY patients (2.8 +/- 0.2 versus 1.9 +/- 0.2 L.min.m2, P < .05, respectively). MSNA was highest in the patients with the lowest LVEF (r = -0.49, P < .05), cardiac index (r = -0.48, P < .05) and 6-minute walking distance (r = -0.50, P < .05). CONCLUSION: Lower sympathetic nerve activities in TCRT patients are related to more favorable cardiac indexes and six minute walking distances suggesting a sympathetic, hemodynamic, and functional improvement by TCRT.