Right Ventricle

This study was designed to evaluate the feasibility of using cylindrical ultrasound transducers mounted on a catheter for the ablation of cardiac tissues. In addition, the effects of ultrasound frequency and power was evaluated both using computer simulations and in vitro experiments. Frequencies of 4.5, 6, and 10 MHz were selected based on the simulation studies and manufacturing feasibility. These transducers were mounted on the tip of 7-French catheters and applied in vitro to fresh ventricular canine endocardium, submerged in flowing degassed saline at 37 degree C. When the power was regulated to maintain transducer interface temperature at 90-100 degree C, the 10-, 6-, and 4.5-MHz transducers generated a lesion depth of 5.9 +/- 0.2 mm, 4.6 +/- 1.0 mm, and 5.3 +/- 0.9 mm, respectively. The 10-MHz transducer was chosen for the in vivo tests since the maximum lesion depth was achieved with the lowest power. Two dogs were anesthetized and sonications were performed in both the left and right ventricles. The 10-MHz cylindrical transducers caused an average lesion depth of 6.4 +/- 2.5 mm. In conclusion, the results show that cylindrical ultrasound transducers can be used for cardiac tissue ablation and that they may be able to produce deeper tissue necrosis than other methods currently in use.

Objective— To report successful surgical treatment of double chambered right ventricle (DCRV) in a cat.Study Design— Clinical report.Animals— Cat with DCRV.Methods— DCRV was diagnosed in a 5-month-old male Maine Coon cat using echocardiography and angiocardiography. At 2 years, despite medical therapy, chylothorax developed. A section of the right ventricular free wall that spanned the fibromuscular obstruction was excised under total venous inflow occlusion (TVIO) using the incised pericardial patch technique.Results— Short-term recovery was complicated by return of chylothorax but this resolved after thoracocentesis and diuretic therapy. Three years after surgery, the cat is free of clinical signs and no longer on any medical therapy.Conclusions— Partial right ventriculectomy can be performed under TVIO through an incised pericardial patch.Clinical Relevance— DCRV in cat can be successfully treated by partial right ventriculectomy performed under TVIO through an incised pericardial patch.

Purpose To confirm the central role of antenatal echocardiography and necropsy in the prenatal diagnosis of rare congenital heart defects. Methods A 33-year-old woman undergoing second trimester scan using 2D transabdominal and Doppler sonography. Results The echocardiographic examination showed, at the level of the four-chamber view, a predominant left ventricle with a rudimental right ventricle and a single artery emerging with failed visualization of the pulmonary trunk: a diagnosis of truncus arteriosus communis associated with tricuspid atresia and hypoplastic right heart was made. No other ultrasound-associated anomalies were seen. Fetal karyotype and 22q11.2 microdeletion for Di George syndrome were sought using cordocentesis performed at 21 weeks and both the results were normal. After extensive counselling, the couple opted for termination of pregnancy at 22 weeks gestation. Necroscopy confirmed the prenatal ultrasound diagnosis. Necroscopy of the heart was performed in a manner that resembled the fetal echocardiographic examination and revealed two atria, two atrio-ventricular valves with recognizable mitral and tricuspid morphology, a prevalent ventricle of left-type and a rudimental ventricle of right type and a ventricular septal defect. The common truncus was seen coming out above the ventricular septum, whilst the pulmonary arteries arise separated from the truncus communis. No other structural thoraco-abdominal anomalies were found. Conclusions A combined diagnostic strategy based on second trimester fetal echocardiography, genetic analysis and necroscopy has made identification of a rare congenital heart disease possible.

In the current era of superb surgical results for congenital heart disease, several management options are available for patients born with double outlet right ventricle (DORV). The surgical repair of DORV is tailored to address the variety of abnormalities associated with this lesion. The treatment strategies are dependent upon the anatomy and relationship of the ventricular septal defect (VSD) and the great arteries. For patients with subaortic or doubly committed VSDs, without right ventricular outflow tract obstruction, the usual repair is an intraventricular tunnel from the VSD to the aorta. If right ventricular outflow tract obstruction exists, then augmentation of the right ventricular outflow tract or conduit placement from the right ventricle to the pulmonary artery is necessary. For the "Taussig-Bing anomaly" (subpulmonary VSD) an arterial switch operation is indicated with tunneling of the VSD to the neoaorta. For patients with a remote VSD, complex atrioventric...

Pulmonary hypertension is characterised by the chronic elevation of pulmonary artery pressure (PAP) and pulmonary vascular resistance (PVR) leading to right ventricular enlargement and hypertrophy. Pulmonary hypertension may result from respiratory and cardiac diseases, the most severe forms occurring in thromboembolic and primary pulmonary hypertension. Pulmonary hypertension is most often defined as a mean PAP >25 mmHg at rest or >30 mmHg during exercise, the pressure being measured invasively with a pulmonary artery catheter. Doppler echocardiography allows serial, noninvasive follow-up of PAPs and right heart function. When the adaptive mechanisms of right ventricular dilatation and hypertrophy cannot compensate for the haemodynamic burden, right heart failure occurs and is associated with poor prognosis. The haemodynamic profile is the major determinant of prognosis. In both primary and secondary pulmonary hypertension, special attention must be paid to the assessment of pulmonary vascular resistance index (PVRI), right heart function and pulmonary vasodilatory reserve. Recent studies have stressed the prognostic values of exercise capacity (6-min walk test), right atrial pressure, stroke index and vasodilator challenge responses, as well as an interest in new imaging techniques and natriuretic peptide determinations. Overall, careful haemodynamic evaluation may optimise new diagnostic and therapeutic strategies in pulmonary hypertension.

Background. The guidelines for performing a one and a half ventricle repair with pulsatile bidirectional Glenn remains controversial. This retrospective report summarizes the experience of a single institution, with an attempt at providing an answer.Methods. Fifty consecutive patients, aged 4 months to 42 years, underwent intracardiac repair along with a superior cavopulmonary connection. Twenty-seven of the patients had had previous surgical palliation. Repair consisted of patch closure of the ventricular septal defect (n = 25), tricuspid valve repair (n = 26), reconstruction of the right ventricular outflow tract (n = 34), transpulmonary annular patch (n = 34), right ventricle to pulmonary artery homograft conduit (n = 4), and concomitant repair of atrioventricular canal (n = 9). Ten patients were left with a fenestration in the atrial septum.Results. There were six hospital deaths (12%) and two late deaths (4.5%). Forty-two survivors were followed from 8 months to 116 months. Eighty-eight percent are in functional class I. Actuarial survival at 97 months was 74%.Conclusions. Moderate right heart hypoplasia constitutes a safe anatomic category for a pulsatile bidirectional Glenn. It is advisable not to proceed with a one and a half ventricle repair if postoperative residual pulmonary artery hypertension is anticipated. Patients requiring an intricate intracardiac repair and those with concomitant right heart hypoplasia may be better suited for a Fontan type of repair to reduce the complexity of the procedure.

Background Abnormalities in right ventricular function are known to occur in patients with pulmonary arterial hypertension. Objective Test the hypothesis that chronic elevation in pulmonary artery systolic pressure delays mechanical activation of the right ventricle, termed dyssynchrony, and is associated with both symptoms and right ventricular dysfunction. Methods Fifty-two patients (mean age 46 ± 15 years, 24 patients with chronic pulmonary hypertension) were prospectively evaluated using several echocardiographic parameters to assess right ventricular size and function. In addition, tissue Doppler imaging was also obtained to assess longitudinal strain of the right ventricular wall, interventricular septum, and lateral wall of the left ventricle and examined with regards to right ventricular size and function as well as clinical variables. Results In this study, patients with chronic pulmonary hypertension had statistically different right ventricular fractional area change (35 ± 13 percent), right ventricular end-systolic area (21 ± 10 cm2), right ventricular Myocardial Performance Index (0.72 ± 0.34), and Eccentricity Index (1.34 ± 0.37) than individuals without pulmonary hypertension (51 ± 5 percent, 9 ± 2 cm2, 0.27 ± 0.09, and 0.97 ± 0.06, p < 0.005, respectively). Furthermore, peak longitudinal right ventricular wall strain in chronic pulmonary hypertension was also different -20.8 ± 9.0 percent versus -28.0 ± 4.1 percent, p < 0.01). Right ventricular dyssynchrony correlated very well with right ventricular end-systolic area (r = 0.79, p < 0.001) and Eccentricity Index (r = 0.83, p < 0.001). Furthermore, right ventricular dyssynchrony correlates with pulmonary hypertension severity index (p < 0.0001), World Health Organization class (p < 0.0001), and number of hospitalizations (p < 0.0001). Conclusion Lower peak longitudinal right ventricular wall strain and significantly delayed time-to-peak strain values, consistent with right ventricular dyssynchrony, were found in a small heterogeneous group of patients with chronic pulmonary hypertension when compared to individuals without pulmonary hypertension. Furthermore, right ventricular dyssynchrony was associated with disease severity and compromised functional class.

The ECG interval from the peak to the end of the T wave (T peak-T end) has been used as an index of transmural dispersion of ventricular repolarization (DVR). The correlation between the T peak-T end interval and the global DVR, however, has not been well-evaluated. Methods: Monophasic action potentials (MAPs) were recorded from 51 ± 10 epicardial and 64 ± 9 endocardial sites in the left ventricles of 10 pigs, and from 41 ± 4 epicardial and 53 ± 2 endocardial sites in the right ventricles of 2 of the 10 pigs using the CARTO mapping system. The end of repolarization times over the epi- and endocardium were measured, and the end of repolarization dispersions over the epicardium (DVR-epi), over the endocardium (DVR-endo) and over both (DVR-total) were calculated. The QTpeak, QTend and T peak-T end intervals as well as the QTpeak and QTend dispersions were obtained from the simultaneously recorded 12-lead ECG. Results: The maximal T peak-T end intervals (57 ± 7 ms) were consistent with the DVR-total (58 ± 11 ms, p > 0.05), and significantly correlated with the DVR-total (r = 0.64, p < 0.05). However, the mean T peak-T end intervals (44 ± 5 ms), and T peak-T end intervals from lead II (41 ± 6 ms) and V 5 (43 ± 5 ms) were all significantly smaller than and poorly correlated with the DVR-total, as were the QTpeak and QTend dispersions (15 ± 2 ms vs. 21 ± 4 ms). Conclusion: The maximal T peak-T end interval may be used as a noninvasive estimate for the global DVR, but not the QTpeak and QTend dispersions, nor the mean T peak-T end interval and that from a single lead.