Doppler superior vena cava flow evolution and respiratory variation in superior vena cava syndrome

BACKGROUND: Superior vena cava syndrome (SVCS) is a clinical expression of obstruction of blood flow through the superior vena cava. The patterns of the Doppler flow changes of superior vena cava (SVC), especially the respiratory effects on them have not yet been fully elucidated. This study was to examine SVC Doppler flow patterns and the respiratory effects on them in healthy subjects and patients with SVCS. METHODS: The SVC Doppler flow patterns of 18 normal human subjects and 22 patients with SVCS were analyzed at initial diagnosis and were followed up every 2 months for at least 11 months. RESULTS: Among the 22 patients, 5 patients with the tumor near the right atrium oppressing the inferior segment of the SVC had clear VR- and AR-waves, while in the other 17 patients the VR- and AR-waves disappeared or their outlines were vague. The respiratory variations of the S- and D-waves as a percentage change in inspiration compared to expiration in patient group were much lower than those in control group (S-wave: 1.67 +/- 3.32% vs. 15.65 +/- 16.15%, P = 0.0003; D-wave: 1.80 +/- 1.12% vs. 23.55 +/- 37%, P = 0.0087), which gradually became larger with treatment and showed no significant difference with those in control group after 7 months. CONCLUSIONS: The Doppler flows of the patients with SVCS correlate well with the images of CT scan of them. The respiratory variation of the S- and D-velocities could be used to evaluate the severity of SVC obstruction and its therapeutic effect.     

Superior vena cava Doppler flow velocity patterns in pericardial disease

Doppler superior vena cava (SVC) flow patterns were studied in 34 patients with pericardial disease and in 8 normal adults; the pulse transducer on the echocardiographic instrument was used for respiratory monitoring, rather than a separate nasal thermistor-based device. First expiratory SVC diastolic flow velocities (Dfe) did not differ in normal subjects and patients with hemodynamically insignificant pericardial effusions (23 +/- 3 cm/s and 29 +/- 13 cm/s, difference not significant). Dfe were less than 15 cm/s only in the 14 patients with cardiac tamponade (9 +/- 3 cm/s, p less than 0.01). A ratio of systolic to diastolic flow velocity less than or equal to 1.1 in the first expiratory beat distinguished constrictive pericarditis from all other groups (p less than 0.01), although not from restrictive cardiomyopathy. Expiratory ablation of diastolic SVC flow mimicking cardiac tamponade was not observed in constrictive pericarditis. Respiratory variation in SVC flow velocities was slight in normal subjects and patients with constrictive pericarditis, increased in patients with hemodynamically insignificant pericardial effusions (p less than 0.01) and greatest in patients with cardiac tamponade (p less than 0.01). Quantitative analysis of SVC flow velocity patterns is a useful addition to the echocardiographic evaluation of pericardial disease.     

Cross-sectional echocardiographic study on persistent left superior vena cava

Twelve patients with persistent left superior vena cava (PLSVC) were studied using high speed cross-sectional echocardiography with mechanical sector scanning. The majority of the examined patients had other associated congenital heart diseases.A circular echo with an echo-free space was demonstrated at the posterosuperior region of the posterior mitral leaflet (PML) in the cross-section of the long cardiac axis. It was also recognized as a narrow tubular cavity echo posterior to the left atrium and the left ventricle in the cross-section of the sagittal plane of the chest. This abnormal echo was gradually enlarged during systole and the unusual cavity was largest in early diastole at the E point of the anterior mitral leaflet (AML), and its anterior margin moved back in middiastole. This abnormal echo seems to be correspond to the left atrioventricular sulcus. By the injection of indocyanine green at the left median cubital vein, the positive contrast echo appeared in the cavity which was considered to be PLSVC, whereas it appeareed neither in the left atrium nor in the left ventricle. This abnormal echo was not recognized in normal subjects and other cardiac diseases without PLSVC.In M-mode echocardiography, the unusual linear echo was recorded behind the AML. It moved anteriorly during systole and went back posteriorly in diastole.Consequently, because of the direction of the echo beam, the movement and the location of the unusual echo, it seems to emanate from the lower part of the PLSVC. High speed cross-sectional echocardiography has proved to be useful for noninvasive diagnosis of the PLSVC.     

A case of absent right superior vena cava with persistent left superior vena cava: Cross-sectional echocardiographic diagnosis

Summary We report a case of absence of the right superior vena cava. Hitherto, the findings in this condition have only been obtained using invasive methods; this report is the first in which the diagnosis was made by means of echocardiography. The findings include a markedly enlarged coronary sinus draining into the right atrium and a specific finding of contrast echocardiography in which contrast material injected into the right antecubital vein can be seen in the enlarged coronary sinus. The contrast echo flows into the right atrium from the coronary sinusonly. The size of the coronary sinus was far beyond the range (91±38 mm²/m²) in patients with persistent left superior vena cava with the presence of the right superior vena cava.     

Apparent pulse wave velocity in the canine superior vena cava

In order to evaluate clinically recorded jugular vein pulses it is necessary to understand the transmission process of the right atrial pressure pulse through the caval veins up to the jugular veins. The transmission speed at distinct points of the venous pressure curve was studied in the superior vena cava of 20 anaesthetised dogs. Under control conditions the propagation velocities varied from 1.2 +/- 0.49 to 2.5 +/- 1.36 m . s-1. During increased preload of the heart propagation velocities rose significantly from 2.2 to 4.2 m . s-1 per kPa as a function of mean venous pressure and from 2.3 to 5.8 m . s-1 per kPa as a function of phasic pressures. Right atrial pacing (between 60 and 120 beats . min-1) did not influence the propagation velocity of the studied distinct points. It was found that the summits of the pressure pulse propagate at only a slightly higher speed than the nadirs.     

Respiratory changes of superior vena cava flow velocity in old myocardial infarction with severe left ventricular dysfunction

The clinical significance of the flow velocity of the superior vena cava (SVC) in old myocardial infarction (OMI) with severe left ventricular dysfunction were evaluated using pulsed Doppler echocardiography. The subjects consisted of 10 patients with OMI (averaged left ventricular ejection fraction: 0.37 +/- 0.11) and 10 age-matched normal controls. Among the patients, eight had extensive anterior infarction and two had both anterior and inferior infarctions. During normal respiration, the peak SVC flow velocities in systole (S) and diastole (D), and the D/S ratio were measured. To evaluate right ventricular diastolic function, we measured the peak velocity across the tricuspid orifice in early diastole (rapid inflow: T-R) and the atrial contraction phase (T-A), and the ratio T-A/T-R during quiet expiration. In the normal controls, S was greater than D, both during expiration and inspiration. During inspiration, S, D and the D/S in the normal controls increased, with a greater increase in D than in S. In the patients, however, D and the D/S did not increase during inspiration. T-R was less and the T-A/T-R was greater in the patients with OMI than in the normal controls. These findings of tricuspid flow velocity revealed impaired diastolic filling of the right ventricle in patients with OMI. In conclusion, the impaired diastolic filling of the right ventricle in patients with OMI might be one of the causes of the abnormal response of the SVC flow velocity during normal spontaneous respiration.     

Echocardiography of the superior vena cava

The anatomy and applied echocardiographic anatomy of the superior vena cava (SVC) are briefly described. Right supraclavicular interrogation of the SVC has been in use for many years, but supraclavicular two-dimensional (2-D) imaging of the SVC has been virtually ignored. We have recently shown that supraclavicular 2-D imaging can provide excellent views of the SVC and its main tributaries. Transthoracic echocardiography (TEE) is suitable for imaging of the lower (juxtaatrial) SVC. Persistence of a left SVC is an uncommon variant, diagnosed echocardiographically by coronary sinus dilatation and passage of contrast into it from a left arm vein. Extensive SVC compression by mediastinal masses is well known, but recently intravascular SVC obstruction has been increasingly reported as a complication of radiofrequency ablation for ectopic atrial tachycardia, for thrombosis of the SVC or its main tributaries following indwelling catheters, or following insertion of pacemaker leads. Doppler interrogation or TEE imaging of the SVC have been used in recent years to elucidate such pathology.     

Simultaneous Doppler blood velocity measurements from aorta and radial artery in normal human subjects

We used two independent, pulsed, range-gated, ultrasonic, Doppler blood velocity meters to record blood velocities in the aorta and a peripheral artery in 32 normal subjects aged 8 to 62 years. Aortic signals were obtained from an unfocussed transducer in the suprasternal notch using a 2.25 MHz instrument. Simultaneous tracings were obtained from the radial or posterior tibial artery using an 8 MHz instrument. The audio Doppler signals were subjected to spectral analysis and mean velocity was calculated at 5 ms intervals during 11 successive heart beats at each site. The increase in mean velocity at the start of systole in the aorta followed a linear pattern for the first 45 ms of ejection in two thirds of the beats, irrespective of the age or size of the subject. A similar linear velocity increase in early systole was seen in the peripheral arterial signals after a delay due to the time taken for the flow wave to pass to the periphery. Thus the constant acceleration seen in aortic blood velocity tracings is transmitted to peripheral arteries in an attenuated and delayed but undistorted form.     

Transesophageal echocardiographic examination of left-sided superior vena cava and azygos and hemiazygos veins

In the present study, we describe our experience in the delineation of the left-sided superior vena cava, azygos vein, and hemiazygos vein, using transesophageal echocardiography.     

Effect of propranolol on the left ventricular response to the Valsalva maneuver in normal subjects

Ten normal subjects performed the Valsalva maneuver before and after the administration of propranolol (1 mg/kg). Changes in left ventricular (LV) size and function were assessed with noninvasive techniques (echocardiography and sphygmomanometer). Data were obtained at baseline, at 20 seconds of the strain phase (phase II) and 10 seconds after the release of strain (phase IV). In the control state (before propranolol), blood pressure decreased during phase II and exceeded baseline after the release of strain ("overshoot") in phase IV; after the administration of propranolol, the pressure overshoot characteristic of phase IV was no longer present. End-diastolic dimension decreased during the strain phase, but returned to baseline values during recovery in both control and propranolol states. LV stress-dimension and stress-shortening relations before and after propranolol indicate that an increase in LV contractility beginning during phase II and extending into phase IV was attenuated after propranolol. Although the absence of phase IV blood pressure overshoot may be clinically useful in identifying patients with impaired left ventricular function, beta-adrenergic receptor blocking agents can also produce this hemodynamic response in the presence of normal ventricular function.     

Analysis of Doppler flow spectra of the superior vena cava in a canine model of acute thromboembolic pulmonary hypertension

We aimed to establish a canine model of acute thromboembolic pulmonary hypertension (ATEPH) and to explore the feasibility of diagnosing pulmonary hypertension (PH) through the Doppler flow spectra of the superior vena cava (SVC). A canine model of ATEPH was developed by infusing thrombus into the right femoral vein. The pulmonary arterial pressure was simultaneously measured via a right heart catheter with the guidance of ultrasound. The maximum systolic peak flow velocity (SPV), ventricular reverse peak flow velocity (VRPV), diastolic peak flow velocity (DPV), and atrial reverse peak flow velocity (ARPV) of the SVC were measured by transthoracic echocardiography. ATEPH was successfully established in 24 dogs (88.9%) with the pulmonary arterial systolic pressure (PASP) greater than 30 mmHg. ARPV increased significantly with the increase of PASP, and was positively correlated with PASP (P<0.001). The ARPV/SPV larger than 0.8 could be better adopted to identify all the subjects with PH in this study. The Doppler flow spectra of the SVC could be employed to assess the severity of ATEPH.