Pressure-volume relationships in the right atrium were examined before and after the creation of acute experimental tricuspid regurgitation in pigs. A 1.3 kHz multielectrode impedance catheter with a measuring current of 4 mA was used to determine instantaneous right atrial pressure and relative blood volume; right atrial dimension was assessed simultaneously with ultrasonic crystals attached t...

Important questions exist about the relative roles of changes in heart rate versus extent of myocardial shortening in regulating fetal cardiac output, because increases in heart rate created by left atrial pacing have been shown to increase right ventricular output and decrease left ventricular output. Since the pacemaker site could importantly influence foramen ovale flow and, hence, each vent...

To assess the relation between atrial natriuretic peptide and ventricular dysfunction, we simultaneously measured both atrial and plasma immunoreactive atrial natriuretic peptide concentrations in rats 4 weeks after myocardial infarction induced by left coronary artery ligation. When compared to controls (n = 39), rats with infarction (n = 16) had markedly elevated plasma immunoreactive atrial ...

Atrial fibrillation (AF) induces a progressive dilatation of the atria which in turn might promote the arrhythmia. The mechanism of atrial dilatation during AF is not known. To test the hypothesis that loss of atrial contractile function is a primary cause of atrial dilatation during the first days of AF, eight goats were chronically instrumented with epicardial electrodes, a pressure transduce...

Contrast echocardiography was used before cardiac catheterisation in 37 patients with atrial septal defect and a left-to-right shunt and in 18 patients with a raised right atrial and ventricular pressure to assess the contrast echo effect in the inferior vena cava. Using two dimensional contrast apical echocardiography we found a negative contrast echo effect within the right atrium in many but...

BACKGROUND It has been proposed that multisite atrial pacing (MSAp) restores atrial electrical activation and prevents atrial fibrillation recurrence; however, single-site Bachmann's bundle pacing (BBp) has also been reported as providing effective atrial resynchronization. Coronary sinus pacing (CSp) leads to reversed impulse propagation within the atria. METHODS AND RESULTS Acute echocardio...

The effects of the site used for atrial pacing on atrial and atrioventricular nodal conduction were assesed in 16 patients. In 13 patients, three atrial pacing sites were used: high right atrium, low lateral right atrium, and midcoronary sinus. Two recording sites were used: low septal right atrium, including His electrogram, and high right atrium. Stimulus (S) to high right atrium interval was...

In 16 adult patients, we performed continuous intraoperative two-dimensional transesophageal echocardiography (2DTEE) to help elucidate the mechanism of myocardial dysfunction that accompanies liver transplantation. In 4 of the 16 patients "paradoxical" motion of the interventricular septum consistent with right ventricular failure was seen. An additional three of the 16 patients showed right a...

BACKGROUND Data from experimental models of atrial flutter indicate that macro-reentrant circuits may be confined by anatomic and functional barriers remote from the tricuspid annulus-eustachian ridge atrial isthmus. Data characterizing the various forms of atypical atrial flutter in humans are limited. METHODS AND RESULTS In 6 of 160 consecutive patients referred for ablation of counterclock...

the anomalous origin of the right coronary artery (rca) as a branch from the left anterior descending artery (lad) is a very rare variation of the single coronary artery anomaly. the anomalous vessel arises from the proximal or midportion of the lad and courses anterior to the pulmonary artery trunk in most instances. in this case report, a 61-year-old woman is introduced who underwent coronary...