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 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Phasic left circumflex coronary artery and aortic blood flow were monitored in six awake dogs during a control period and at several degrees of cardiac tamponade. A mean pericardial pressure of 24 plus or minus 3 mm Hg (mean plus or minus SEM) was attained at the maximum tamponade level. Total left circumflex coronary blood flow decreased 51% while the systolic portion of this flow became negative or retrograde. Following acute relief of the tamponade, a coronary hyperaemic response was noted. It it suggested that myocardial ischaemia may be partially responsible for the depressed cardiac function seen in this condition and that extravascular compression of the epicardial vessels may limit the coronary blood flow during systole.
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PMID:The effect of cardiac tamponade on coronary haemodynamics in the awake dog. 12 83

DC shocks within the coronary sinus have been abandoned because of the risk of cardiac rupture and tamponade. Catheter ablation using DC energy to electrodes straddling the ostium of the coronary sinus, when used clinically, has been reported to result in cardiac tamponade in as many as 16% of patients. A new system of energy delivery maximizes voltage while decreasing the undesirable effects caused by barotrauma. This system includes 1) a low-energy ablation power supply with a brief time-constant capacitive discharge that delivers up to 40 J and 3,000 V and 2) a low-energy ablation catheter with a contoured distal electrode. We performed in vitro and in vivo studies of this new system and compared arcing shocks with nonarcing shocks. Ablations were performed using unipolar distal shocks (D) and unipolar shocks to both electrodes made electrically common (P-D). In vitro studies were done in a large tank filled with physiological saline while recording voltage, current, and pressure. High-speed cinematography (32,000 frames/sec) of shocks of 10-40 J permitted detailed analysis of the vapor globe. Anodal shocks of less than 20 J showed no arcing or only minimal vapor globe formation. For D and P-D anodal shocks of 40 J, the diameters of the vapor globe were 31 and 22 mm, respectively, corresponding to pressure recordings of 11 and 4.9 atm. The pressure rise lasted less than 50 mu sec. In vivo studies involved 18 dogs that received nonarcing shocks (one to six shocks of 15 J) and 18 dogs that received arcing shocks (one to three shocks of 40 J). Each group was divided between D and P-D shocks; catheter ablation was performed at a mean +/- SEM distance of 2.94 +/- 0.92 cm within the coronary sinus. All dogs tolerated the procedure without cardiac rupture or tamponade. When killed 2-4 days later, the dogs had edema and hyperemia or hemorrhage in the area of the coronary sinus. We compared the effects of multiple (three to six) nonarcing shocks with the effects of one to three arcing shocks. Disruption or rupture of the coronary sinus within the epicardial fat space occurred in two of 12 dogs (17%) with multiple nonarcing shocks but in 13 of 18 dogs (72%) with arcing shocks (p less than 0.003). Occlusion of the coronary sinus occurred in two of 12 dogs (17%) with multiple nonarcing shocks and in nine of 18 dogs (50%) with arcing shocks (p less than 0.06).(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:In vitro and in vivo effects within the coronary sinus of nonarcing and arcing shocks using a new system of low-energy DC ablation. 198 86

We studied the response of atrial natriuretic peptide to the hemodynamic and renin-aldosterone variations occurring in four patients who developed cardiac tamponade, either occurring in idiopathic fashion in one or secondary to metastatic involvement of the pericardium in three. Right atrial pressure, heart rate and arterial blood pressure were monitored and serial blood samples were taken before and over three hours after pericardiocentesis. During cardiac tamponade, normal levels of atrial natriuretic peptide (mean +/- SEM: 54 +/- 7.4 pg/ml) were observed in the plasma despite increased right atrial pressure (23 +/- 3.8 cm H2O) and heart rates (98 +/- 4.4). Removal of pericardial fluid (540 to 1160 ml) was associated at first with a 200% increase in plasma concentrations of atrial natriuretic peptide (108 +/- 8.8 pg/ml; P less than 0.001), then with a gradual decline toward normal levels, simultaneous with the normalization of right atrial pressure and heart rate. Activity of renin and concentrations of aldosterone in the plasma were increased during tamponade and returned gradually to normal after pericardiocentesis (3.8 +/- 0.9 to 1.2 +/- 0.3 ng/ml/h and 20 +/- 4.2 to 9 +/- 3.2 ng/dl, respectively; P less than 0.01). These data confirm that atrial strain, not intracavitary pressure in itself nor heart rate, is the main determinant of the acute release of atrial natriuretic peptide, which is associated with a suppressing effect on the renin-aldosterone system. In addition, our data indicate that secretion of atrial natriuretic peptide during cardiac tamponade is not stimulated by secondary hyperaldosteronism.
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PMID:Atrial strain is the main determinant of release of atrial natriuretic peptide. 214 62

1. In order to study the role of atrial pressure and atrial stretch on the release of atrial natriuretic peptide we have measured plasma atrial natriuretic peptide concentration, urine output and haemodynamic variables in eight patients during and 30 min after the relief of cardiac tamponade. This condition is characterized by high atrial pressure with little or no atrial stretch. 2. Relief of tamponade was associated with a rise in urine output (53 +/- 27.9 to 101 +/- 24.5 ml/h, mean +/- SEM; P = 0.09), systolic blood pressure (95 +/- 9.6 to 126 +/- 7.0 mmHg, P less than 0.0001), and plasma atrial natriuretic peptide concentration (369.5 +/- 70.9 to 490.3 +/- 94.7 pg/ml, P less than 0.05) despite a large fall in right atrial pressure (18.6 +/- 1.6 to 9.5 +/- 1.3 mmHg, P less than 0.001). 3. These results suggest, therefore, that an increase in atrial stretch, rather than in atrial pressure, stimulates the release of atrial natriuretic peptide.
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PMID:Effect of cardiac tamponade on atrial natriuretic peptide concentrations: influence of stretch and pressure. 217 59

Factors regulating the secretion of atrial natriuretic hormone (ANH) and arginine vasopressin (AVP) have not been elucidated fully. In several studies the release of these peptides has been studied by inducing both increased atrial pressure and atrial distension. A few studies employ cardiac tamponade, allowing the effect of atrial pressure and atrial stretch to be studied separately. In eleven dogs with spontaneous cardiac tamponade the effect of pericardiocentesis on circulating concentrations of ANP and AVP was studied. Pericardiocentesis was followed by a prompt rise in (non-elevated) plasma ANH concentrations from 21.6 +/- 7.3 to 65.4 +/- 17.1 pmol/l (mean +/- SEM). The initially slightly elevated AVP concentration of 5.5 +/- 1.5 pmol/l declined following pericardiocentesis to 2.1 +/- 0.5 pmol/l. In three dogs the systolic arterial pressure was measured indirectly and the central venous pressure was measured with a fluid-filled catheter. Before and after pericardiocentesis arterial pressure readings did not change significantly. Central venous pressure values showed an immediate very steep significant decrease after centesis. It is concluded that ANH release is primarily regulated by stretch and not by atrial pressure, that plasma AVP concentrations are moderately elevated in cardiac tamponade and that in cardiac tamponade pericardiocentesis causes a rapid decline in plasma AVP concentration.
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PMID:Effect of pericardiocentesis on circulating concentrations of atrial natriuretic hormone and arginine vasopressin in dogs with spontaneous pericardial effusion. 816 64

The interdigestive migrating motor complex (MMC) has been demonstrated to be a reliable indicator of intestinal motility and function. The effects of low perfusion on the MMC have never been studied. Fourteen newborn Yorkshire piglets (5 to 18 days old, weighing 2.9 +/- 0.4 kg) underwent celiotomy under general anesthesia with placement of four jejunal electrodes (50 cm apart) as well as a superior mesenteric artery (SMA) Doppler flow probe and a pericardial catheter. Group 1 (n = 5) had operation alone. Group 2 (n = 9) had nonocclusive mesenteric ischemia induced by reversible cardiac tamponade for 5 hours between postoperative days 6 to 12. All subjects had MMC phase III electrical activity, cycling time, and propagation velocity recorded daily. In group 2 MMCs were recorded prior to and during ischemia, and during reperfusion. Group 2 animals had 75% +/- 4% decrease in SMA flow during the tamponade period. During the ischemic period, the MMC cycling time (CT) increased from 67 +/- 10 (mean +/- SEM) to 98 +/- 12 minutes (P < .05) and MMC propagation velocity (PV) decreased to 4.2 +/- 2.2 from a baseline value of 10.5 +/- 1.5 cm/min (P < .05). During reperfusion CT and PV values were not significantly different from baseline. The validity of this model is confirmed by the comparable baseline recordings in groups 1 and 2, and by the return of MMC to baseline values within 4 to 7 hours of reperfusion, as seen in group 2.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The effects of ischemia and reperfusion on intestinal motility. 846 47

The aim of this study was to evaluate the effectiveness and side-effects of intrapericardial administration of cisplatin (IAC), in cases of abundant malignant pericardial effusion (MPE) and/or cardiac tamponade occurring in the course of adenocarcinoma of the lung (AL). Fifteen consecutive patients with abundant MPE and AL (4 females and 11 males; mean age 54 yrs) entered this prospective study. Following pericardiocentesis and insertion of a polyurethane catheter, the pericardial fluid was drained. Malignant aetiology of the pericardial fluid was confirmed by cytological examination. After confirmation of MPE, cisplatin (10 mg in 20 mL normal saline) was instilled directly into the pericardial space, over a period of 5 min for 3-5 consecutive days. Treatment was considered successful (response) if the patient survived 30 days without recurrence of symptoms of abundant MPE, and no other interventions directed to the pericardium were required. Response was achieved in 10 patients (67%). The mean (+/-SEM) dose of cisplatin was 56 (+/-18.9) mg. There were no complications related to the pericardiocentesis. Transient atrial fibrillation was detected in one patient. Mild nausea also occurred in one case. No hypotension or retrosternal pain was observed. Sclerotization of the pericardium and pericarditis constrictiva were detected after IAC in only one case. Cisplatin administered directly into pericardial space is effective and safe. Intraperitoneal administration of cisplatin appears to be the method of choice in the treatment of recurrent malignant pleural effusion in patients with primary adenocarcinoma of the lung. Sclerosis of the pericardial space is a very rare complication observed after intraperitoneal administration of cisplatin therapy.
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PMID:Intrapericardial administration of cisplatin in treatment of metastatic pericardial involvement in adenocarcinoma of the lung. 927 Feb 45

Location of the tip of a central venous catheter (CVC) within the pericardium has been associated with potentially lethal cardiac tamponade. Because the pericardium cannot be seen on chest x-ray (CXR), an alternative radiographic marker is needed for correct placement of CVCs. The anatomy of the region was studied in 34 cadavers. The carina was a mean (SEM) distance of 0.4 (0.1) cm above the pericardial sac as it transverses the superior vena cava (SVC). In no case was the carina located below the pericardial sac. The carina is a reliable, simple anatomical landmark for the correct placement of CVCs. In almost all cases, the carina is radiologically visible even in poor quality, portable CXRs. CVC tips should be located in the SVC above the level of the carina in order to avoid cardiac tamponade.
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PMID:The carina as a landmark in central venous catheter placement. 1157 82