Twenty-year follow-up of acute type a dissection: the incidence and extent of distal aortic disease using magnetic resonance imaging.

A persistent distal false lumen (PDFL) after surgical repair of type A aortic dissection is the most important factor in determining long-term survival. It has been suggested that changes in surgical technique reduce the incidence of distal false lumen. We report the findings of a 20-year follow-up (mean 5.2 years) on 87 patients who have undergone surgical repair of type A aortic dissection with all survivors undergoing magnetic resonance (MR) scanning of the entire aorta. Early mortality was 27.5%, and actuarial 5-, 10-, and 15-year survival was 65%, 28% and 20% respectively. Early mortality had decreased to 18% in the last 5 years. The most common cause of late death was related to distal aortic disease, accounting for 47% of all late deaths with a peak incidence at 7-10 years after surgery. The incidence of PDFL in survivors was 72%, despite the fact that 82% of all intimal tears were resected at time of operation. Incidence was not affected by extension of the repair into the aortic arch nor by the use of the open technique or Gelatin-Resorcine-Formal tissue glue. In patients with a distal false lumen 6% had reached a maximum aortic diameter of 6 cm in at least one plane on MR scanning and 25% had reached 5 cm. We conclude that if dissection has extended beyond the arch at time of presentation then the choice of surgical technique does not prevent the persistance of a distal false lumen. MR scanning gives ideal anatomical and functional assessment of distal aortic disease and provides the surgeon with all the necessary information to plan the timing and indications for further surgery.

A rare cause of profound cyanosis after Kawashima modification of bidirectional cavopulmonary anastomosis.

The expected level of systemic arterial saturation may not be present after bidirectional superior cavopulmonary anastomosis in children with complex congenital cardiac anomalies. We present a case of persistent severe cyanosis in a patient with azygos continuation of the inferior vena cava after bidirectional superior cavopulmonary anastomosis (Kawashima procedure) due to an intrahepatic venovenous malformation. Subsequent transcatheter deployment of two Rashkind double umbrella devices into the malformation reduced the shunt and markedly improved systemic arterial saturation.

Effect of frequency and impulse pattern on the non-cholinergic cardiac response to vagal stimulation in the toad, Bufo marinus.

In the toad, Bufo marinus, stimulation of the vagosympathetic trunk to the heart in the presence of cholinergic and adrenergic blockade results in cardiac slowing. This study investigates the importance of impulse pattern and frequency of neural stimulation in determining this cardiac response. When 360 stimuli were delivered to the heart either continuously at 3 Hz for 2 min, 4 Hz for 1.5 min or 6 Hz for 1 min, or in pulses at 6 Hz for 1 s every 2 s, over a 2 min period, there were no significant differences in the size of the chronotropic responses observed. However, when 360 stimuli were delivered in pulses at 6 Hz for 0.5 s every 1 s over 2 min, the resulting cardiac slowing was significantly greater than in response to the other stimulus regimens. In addition, the cardiac slowing in response to 8 Hz for 0.5 s every 1 s over 2 min was significantly greater than the response to 4 Hz continuously for 2 min. The results provide evidence to support the suggestion that the non-cholinergic, non-adrenergic cardiac response to stimulation of the vagosympathetic trunk is peptidergic in origin, and that the frequency of impulses is important in the gain of the response.

Canine left ventricular volume response to mechanical ventilation with PEEP.

To determine the cause of decreased cardiac output (CO) resulting from the use of PEEP, hemodynamic and pulmonary parameters and radiographic estimates of left ventricular volumes were observed in nine dogs under three conditions: control, PEEP (15 cm H2O), and PEEP with intravascular (IV) volume expansion. Volume expansion was sufficient to return the CO to control values. Cardiac index (CI), stroke volume index (SI), left ventricular stroke work index (LVSWI) all decreased approximately 30 per cent with the application of PEEP. Ejection fraction remained unchanged. With IV volume expansion, the CI, SI, left ventricular end-diastolic volume index, and LVSWI returned to approximate control values. The transmural left ventricular end-diastolic pressure (TMLVEDP) did not change significantly. The authors therefore conclude that reduced left ventricular preload is the cause of decreased cardiac output by PEEP and that indirect evidence of preload (transmural left ventricular end-diastolic pressure) is not an adequate assessment of the force-length relationship under the conditions stated.

Coronary sinus-left atrial window.

Left atrial-coronary sinus fenestration is a rare cause of a left-to-right or right-to-left shunt which occurs most commonly with a persistent left superior vena cava. These fenestrations may represent the only pathway for an obligatory right-to-left or left-to-right shunt in atrioventricular valve atresia. Four cases are presented.

Echophonocardiographic diagnosis of left ventricular pseudoaneurysm.

We report the presence of an unusual systolic murmur associated with a traumatic left ventricular pseudoaneurysm. Echophonocardiographic studies showed the murmur to begin at the first heart sound, but end well before the second heart sound. It seems likely that the murmur is caused by the systolic flow of blood from the left ventricle into the relatively noncompliant pseudoaneurysm. The echocardiographic scan of the left ventricle demonstrated a relatively echo-free space posterior to the left ventricular wall, supporting the diagnosis of pseudoaneurysm, which has confirmed with angiographic studies and at surgery. These findings indicate that a combination of noninvasive techniques is useful in establishing this diagnosis.