Effects of positive-pressure ventilation, pericardial effusion, and cardiac tamponade on respiratory variation in transmitral flow velocities

OBJECTIVE

To determine the effects of positive-pressure ventilation and experimentally induced pericardial effusion and tamponade on transmitral flow velocities in dogs.

DESIGN

Descriptive.

SETTING

University laboratory.

PARTICIPANTS

Eleven tracheally intubated and mechanically ventilated dogs.

INTERVENTIONS

Experimental pericardial effusion and cardiac tamponade were created by pericardial injection of warm saline.

MEASUREMENTS AND MAIN RESULTS

Hemodynamic parameters and pericardial pressures were monitored in the 11 dogs. Pulsed-wave Doppler tracings of mitral valve flow were obtained at the leaflet tips along with hemodynamic measurements at 4 stages: control, effusion (no decrease in mean arterial pressure), tamponade (>or=40% decrease in mean arterial pressure), and tamponade relief (after evacuation of pericardial fluid). Maximal variation (36%) in transmitral flow velocity over the respiratory cycle during positive-pressure ventilation was seen in the control stage. In the effusion and tamponade stages, variation in transmitral flow velocity decreased progressively to 29% (p = 0.1804, not significant) and 16% (p < 0.0001), respectively.

CONCLUSION

Intrathoracic pressure and lung volume changes caused by positive-pressure ventilation influence transmitral flow velocity patterns. Respiratory variation in transvalvular flow is pronounced during standard positive-pressure mechanical ventilation, decreases in the presence of pericardial effusion, and becomes almost nonexistent when cardiac tamponade is present. These findings show that the echocardiographic criteria used to diagnose cardiac tamponade based on mitral valve inflow patterns are different during positive-pressure ventilation from spontaneously breathing subjects.

Hemodynamically unstable pericardial effusion in the Intensive Cardiac Unit: prospective study

The authors have conducted a prospective investigation on 15 patients with hemodynamically unstable pericardial effusion (main criteria: echocardiographic signs of various degrees of right ventricular diastolic collapse and clinical instability) hospitalized in the Intensive Cardiac Unit (1.97% of all patients) for one year and have compared the results with literature data. The causes of pericardial effusion were neoplasms, infections, rupture of heart of aorta and hypothyroidism. Investigation revealed the most frequent findings: symptoms (dyspnea, retrosternal pain, loading intolerance, nonproductive cough), clinical signs (soft heart sounds, changes in pulmonal findings, fever, jugular venous distention, tachycardia, arterial hypotension and hepatomegaly), laboratory changes (elevated erythrocyte sedimentation rate, leukocytosis), ECG changes (ST-T abnormality, microvoltage, tachycardia) and chest X-rays changes (enlarged cardiac silhouette, pleural effusion). Echocardiography found an average width of pericardial effusion of 2.5 cm (+/- 1.2), frequently thickened pericardium and changes in heart motions. The most used drugs in therapy were indomethacin, antibiotics, analgesics and corticosteroids. In three patients pericardiocentesis, and in two pericardiectomy were performed. Two patients died, 13 patients were discharged from the ICU with an improved health condition. Literature data on this condition are either lacking, or differ from the above findings.

Pericardial disease in the oncology patient

Malignant pericardial disease is a serious and common problem seen in patients with cancer. It is usually due to metastatic spread of the underlying malignancy or a complication of radiation therapy. The patient may have a mild, subtle presentation, as is often seen in the early stages of pericardial effusion, or may experience dramatic hemodynamic compromise, as is seen with cardiac tamponade and constrictive pericarditis. There are many treatment options available that range from simple drainage to thoracic surgery. It is essential that the treating physician choose a treatment plan in the context of the cancer stage and the patient's prognosis. This article discusses the incidence, pathophysiology, clinical presentation, diagnosis, and treatment options in the various types of malignant pericardial disease.

Cardiac tamponade masking clinical presentation and hemodynamic effects of papillary muscle rupture after acute myocardial infarction

A 67-year-old woman sustained an acute lateral-wall myocardial infarction and was treated with thrombolytic therapy. Postinfarction hypotension developed 3 days later. Clinical findings at that time were consistent with cardiac tamponade, and an echocardiographic study revealed a moderate-sized pericardial effusion. She underwent urgent pericardiocentesis with transient improvement in hemodynamics, followed by deterioration associated with the development of acute pulmonary edema. Follow-up transesophageal echocardiographic imaging revealed papillary muscle rupture with severe mitral regurgitation. The patient underwent urgent surgical intervention consisting of coronary artery bypass grafting and mitral valve replacement. The presence of cardiac tamponade in this patient masked the clinical manifestations of papillary muscle rupture through the hemodynamic effect of tamponade physiology on mitral regurgitation.

Mild hypothermia alters the oxygen consumption/delivery relationship by decreasing the slope of the supply-dependent line

OBJECTIVE

To evaluate the effect of mild hypothermia on the relationship between systemic oxygen consumption and oxygen delivery.

DESIGN

Prospective animal study.

SETTING

University research laboratory.

SUBJECTS

Anesthetized and ventilated rabbits.

INTERVENTIONS

Rabbits were subjected to stepwise cardiac tamponade to reduce oxygen delivery while body temperature was maintained at 34 degrees C (group H, n = 8) or 39 degrees C (group N, n = 8).

MEASUREMENTS AND MAIN RESULTS

The oxygen consumption/oxygen delivery relationship was analyzed by the dual-line method. The slope of the supply-dependent line was significantly decreased in group H (y = 0.57x + 1.3) compared with that in group N (y = 0.72x + 1.7), indicating that the ability of tissues to extract oxygen was impaired during hypothermia. Consequently, the proportion of the supply-independent area over the entire range of oxygen delivery was decreased in response to hypothermia.

CONCLUSION

The potential for tissue hypoxia is likely to be increased during hypothermia when the circulation becomes unstable and oxygen delivery decreases.

Diastolic heart failure: restrictive cardiomyopathy, constrictive pericarditis, and cardiac tamponade: clinical and echocardiographic evaluation

An understanding of the basic principles of diastolic function is important in order to recognize diseases that may result in diastolic dysfunction and diastolic heart failure. Although uncommon, restrictive cardiomyopathy, constrictive pericarditis, and cardiac tamponade are among the disorders that may affect primarily diastolic function with preservation of systolic function. Diastolic heart failure may manifest with chronic nonspecific symptoms or may present with acute hemodynamic compromise. Echocardiography plays a vital role in the diagnosis of diastolic dysfunction and differentiation of these disease processes. It also provides a basis for clinical decisions regarding management and surgical referral. This review summarizes the clinical features, pathophysiology, and hemodynamic and echocardiographic signs of restrictive cardiomyopathy, constrictive pericarditis, and cardiac tamponade.

Jejunal luminal microdialysate lactate in cardiac tamponade--effect of low systemic blood flow on gut mucosa

OBJECTIVE

To assess gut mucosal metabolic response and susceptibility to dysoxia during low systemic blood flow induced by cardiac tamponade.

DESIGN

A randomized, controlled animal experiment.

SETTING

National laboratory animal center.

INTERVENTIONS

Cardiac tamponade was induced in six pigs, while six additional pigs served as controls. In the tamponade group, fluid was injected into the pericardial space to reduce aortic flow, aiming first at a flow of 50 ml/kg per min and then at 30 ml/kg per min. Each step lasted for 60 min.

MEASUREMENTS AND RESULTS

We measured luminal lactate by microdialysis and mucosal PCO(2) by tonometry in the mid-jejunum. Aortic and superior mesenteric artery blood flow, arterial and mesenteric venous lactate, pyruvate and ketone bodies and regional lactate exchange were measured. The distribution of aortic blood flow to superior mesenteric artery remained unchanged (baseline 14 (12-16)%; median (interquartile range), stepwise flow reduction 11 (10-17)% and 13 (12-19)%, NS) during reduction of aortic blood flow from 81 (61-95) ml/kg per min to 49 (47-49) ml/kg per min and 23 (21-27) ml/kg per min. Systemic hyperlactatemia developed early, whereas gut luminal lactate increased only after 60 min of hypoperfusion and could be largely explained by arterial hyperlactatemia. Mesenteric venous lactate-to-pyruvate (L/P) ratio increased after 30 min of tamponade, but both venous-arterial lactate and pyruvate gradients turned negative (gut lactate and pyruvate uptake). Mesenteric venous ss-hydroxybutyrate to acetoacetate ratio increased after 60 min. No changes were observed in the controls.

CONCLUSIONS

Jejunal mucosal dysoxia and anaerobic metabolism occurs late during low systemic blood flow induced by experimental cardiac tamponade.

Simultaneous malignant hypertension and cardiac tamponade

Malignant hypertension and cardiac tamponade are uncommon but potentially life-threatening medical emergencies. Both conditions may be associated with collagen vascular diseases, such as systemic lupus erythematosus. We report a case of acute cardiac tamponade associated with malignant hypertension secondary to lupus nephritis. Immediately after pericardiocentesis, blood pressure declined substantially. Although malignant hypertension is seen with modest frequency in patients with systemic lupus erythematosus, true cardiac tamponade is a less common complication of lupus serositis. Acute, simultaneous presentation of both life-threatening entities and the hemodynamic course have not been described.

[Cardiac tamponade as a complication of central line catheterization in newborns]

Two cases with cardiac tamponade in neonates, one of which eventuated in death, are presented. The total tamponade rate was 0.27%. Several hours after catheterization patients suddenly developed bradycardia, hypotension, and signs of decompensation, all within an hour. One patient died and the diagnosis was made at autopsy. In the other patient ultrasonography showed a clear echo-free space between the epicardium and pericardium, with the tip of the catheter in contact with the atrial wall. Percutaneous pericardiocentesis was performed under cardiographic guidance; 11 ml of hemorrhagic fluid containing 26 mmol/liter glucose were aspirated. The catheter tip was then repositioned to the vena cava superior. Hemodynamic status rapidly improved and this patient survived. A review of relevant publications is offered.

Pathophysiologic mechanisms in pericardial disease

The pericardium influences cardiac performance indirectly, but pathologic conditions may have profound effects on cardiac function. In recent years, several imaging modalities have been useful, both clinically and in understanding the pathophysiology of pericardial diseases. Rising pericardial pressures progressively reduce the average transmural pressure of the right and subsequently left cardiac chambers, compromising filling and output. This has become more relevant today, with the increased incidence of cardiac tamponade, attributed to the increased use of antiplatelet agents in combination with a more widespread use of invasive devices. On another front, although an uncommon diagnosis, constrictive pericarditis may be missed despite the excellence of a variety of noninvasive methods, and remains a difficult one to make.Introduction

Recent role of imaging in the diagnosis of pericardial disease

Noninvasive cardiac imaging techniques have made a striking impact on the evaluation and management of pericardial disorders. Two-dimensional and Doppler echocardiography are the methods of choice in the evaluation of pericardial effusion and cardiac tamponade. Magnetic resonance imaging, computed tomography, and transesophageal echocardiography are valuable in the assessment of pericardial thickness in suspected cases of constrictive pericarditis. Filling dysfunction associated with constrictive pericarditis is well demonstrated by Doppler flow velocity recordings of intracardiac flow jets, and pulmonary and hepatic venous flow streams. Tissue Doppler echocardiography, by which tissue velocity of myocardial regions and mitral annulus are analyzed, offers additional information in the differentiation of constrictive pericarditis and restrictive cardiomyopathy. Magnetic resonance imaging and computed tomography are the techniques of choice in the recognition of unusual disorders such as pericardial cysts, tumors invading the pericardium, and congenital absence of pericardium. Noninvasive imaging aids not only in the diagnosis of pericardial diseases, but also in the guidance of optimal therapy.

Normovolemic hemodilution improves oxygen extraction capabilities in endotoxic shock

We studied the effects of normovolemic hemodilution on tissue oxygen extraction capabilities in a canine model of endotoxic shock. Eighteen anesthetized and mechanically ventilated dogs underwent normovolemic hemodilution with 6% hydroxyethyl starch solution to reach hematocrit (Hct) levels around 40, 30, or 20% before the administration of 2 mg/kg of Escherichia coli endotoxin. Cardiac tamponade was then induced by repeated injections of normal saline into the pericardial sac to reduce cardiac output and study whole body oxygen extraction capabilities. Whole body critical oxygen delivery was lower in the Hct 20% and 30% groups (8.4 +/- 0.4 and 10.4 +/- 0.7 ml. kg(-1). min(-1), respectively) than in the Hct 40% group (12.8 +/- 0.8 ml. kg(-1). min(-1)) (both P < 0.005). The whole body critical oxygen extraction ratio was higher in the Hct 30% and 20% groups (49.1 +/- 8.2 and 55.2 +/- 4.6%, respectively) than in the Hct 40% group (37.1 +/- 4.4 %) (both P < 0.05). Liver critical oxygen extraction ratio was also higher in the Hct 30% and 20% groups than in the Hct 40% group. The arterial lactate concentrations and the gradient between ileum mucosal PCO(2) and arterial PCO(2) were lower in the Hct 20% and 30% groups than in the Hct 40% group. We conclude that, during an acute reduction in blood flow during endotoxic shock in dogs, normovolemic hemodilution is associated with improved tissue perfusion and increased oxygen extraction capabilities.

Cardiomyopathy and pericardial tamponade in ulcerative colitis

Cardiac complications of inflammatory bowel disease are rare; the most commonly reported complication is pericarditis. Drugs containing 5-aminosalicylic acid have been implicated as the cause of pericarditis in inflammatory bowel disease. A male patient with ulcerative colitis who was not taking any 5-aminosalicylic acid-containing drugs, but who developed a severe myopericarditis mimicking an acute myocardial infarction, is described. He subsequently required therapeutic pericardiocentesis for his worsening cardiac tamponade. The literature on cardiac complications of inflammatory bowel disease is reviewed.

Noninvasive/invasive correlates of exaggerated ventricular interdependence in cardiac tamponade

Ventricular interdependence is that property of the normal heart such that distension of one ventricle alters the distensibility and filling pressure of the other. This phenomenon coupled with reciprocal changes in right and left heart venous return during normal quiet respiration results in minor decreases in left ventricular stroke volume, systolic blood pressure, pulse pressure, total electromechanical systole (Q-A2), left ventricular ejection time and mitral e-wave velocity during inspiration and minor increases in these parameters during expiration. Opposite changes in these parameters occur in the right heart with increases occurring during inspiration and decreases during expiration. Exaggerated ventricular interdependence occurs in cardiac tamponade when the pericardial constraint limits the total contents in the pericardial sac. This, together with the decreased effective left ventricular filling pressure which occurs during inspiration, is responsible for the exaggerated decrease in stroke volume, blood pressure, pulse pressure, left ventricular ejection time and mitral e-wave velocity in this condition. These observations, together with the echocardiographic findings of right atrial collapse, right ventricular collapse, and inferior vena cava plethora constitute the noninvasive diagnosis of pericardial tamponade. The utility of these noninvasive tests in detecting both the presence and degree of increased pericardial pressure was evaluated in 33 invasively studied patients with pericardial effusion. In Group 1 (n = 13) intrapericardial pressure was elevated but less than both right atrial pressure and pulmonary wedge pressure, in Group 2 (n = 10) intrapericardial pressure equaled right atrial pressure but was less than pulmonary wedge pressure, and in Group 3 (n = 10) intrapericardial pressure equaled right atrial pressure and pulmonary wedge pressure. From these data it is concluded that right atrial and right ventricular collapse are highly sensitive techniques for predicting increased intrapericardial pressure in all three groups, but fail to predict the level of intrapericardial pressure and the severity of hemodynamic compromise. However, the absence of inferior vena cava plethora helped separate Group 1 patients from Groups 2 and 3 patients, thereby aiding in distinguishing a group of patients with severe hemodynamic derangement requiring urgent intervention. Exaggerated reciprocal changes in mitral and tricuspid e-wave velocity is a very sensitive finding for increased intrapericardial pressure. However, its presence correlates poorly with the severity of tamponade. Acute pericardial tamponade is a clinical diagnosis determined by the integration of the history, physical exam and appropriate noninvasive physiologic and imaging techniques.

Changes in QRS voltage in cardiac tamponade and pericardial effusion: reversibility after pericardiocentesis and after anti-inflammatory drug treatment

OBJECTIVES

The goal of this study was to define the association between low QRS voltage and cardiac tamponade or pericardial effusion and to assess the reversibility of low QRS voltage after therapeutic procedures.

BACKGROUND

It is unclear whether low QRS voltage is a sign of cardiac tamponade or whether it is a sign of pericardial effusion per se.

METHODS

In a prospective study design, we recorded consecutive 12-lead electrocardiograms and echocardiograms in 43 patients who were referred to our institution for evaluation and therapy of a significant pericardial effusion. Cardiac tamponade was present in 23 patients (53%). Low QRS voltage (defined as maximum QRS amplitude <0.5 mV in the limb leads) was found in 14 of these 23 subjects (61%). Nine of these 14 patients were treated by pericardiocentesis (group A). Five patients received anti-inflammatory medication (group B). Group C consisted of nine patients with pericarditis and significant pericardial effusion who had no clinical evidence of tamponade.

RESULTS

In group A, low QRS voltage remained largely unchanged immediately after successful pericardiocentesis (0.36 +/- 0.17 mV before vs. 0.42 +/- 0.21 mV after, p = NS), but QRS amplitude recovered within a week (0.78 +/- 0.33 mV, p < 0.001). In group B, the maximum QRS amplitude increased from 0.40 +/- 0.20 mV to 0.80 +/- 0.36 mV (p < 0.001) within six days. In group C, all patients had a normal QRS amplitude initially (1.09 +/- 0.55 mV) and during a seven-day follow-up (1.10 +/- 0.56 mV, p = NS).

CONCLUSIONS

Low QRS voltage is a feature of cardiac tamponade but not of pericardial effusion per se. Our findings indicate that the presence and severity of cardiac tamponade, in addition to inflammatory mechanisms, may contribute to the development of low QRS voltage in patients with large pericardial effusions.

Assessment of pseudohypertrophy as a measure of left-ventricular compression in patients with cardiac tamponade

BACKGROUND

Left-ventricular pseudohypertrophy reflecting left-ventricular compression was reported in a selected group of patients with cardiac tamponade.

HYPOTHESIS

Criteria for the presence of pseudohypertrophy can be established to guide its use as a sign of left-ventricular compression in patients with cardiac tamponade.

METHODS

Left-ventricular wall thickness, diameters, relative diastolic wall thickness (%) = (posterior wall thickness/end diastolic radius) x 100 and estimated left-ventricular mass were measured in patients with small, moderate and large pericardial effusion, in patients with cardiac tamponade before and after pericardiocentesis (16 patients in each group) and in 30 control subjects with normal echocardiograms.

RESULTS

Left-ventricular posterior wall thickness was increased (12 +/- 2 vs. 9 +/- 1 mm, p < 0.001), left-ventricular end-diastolic diameter was reduced (3.9 +/- 0.5 vs. 4.6 +/- 0.3 cm, p < 0.001) and relative left-ventricular diastolic wall thickness was increased (61 +/- 13 vs. 41 +/- 4.5%, p < 0.001) only in patients with cardiac tamponade compared to controls, but not in patients with small, moderate and large effusions, respectively (relative wall thickness: 42 +/- 5, 41 +/- 7 and 44 +/- 7%, p = NS). Mean values of the estimated left-ventricular mass were similar in all groups. Following pericardiocentesis all parameters were normal.

CONCLUSIONS

Despite normal left-ventricular mass, relative left-ventricular diastolic wall thickness is elevated in patients with cardiac tamponade. In contrast it is normal in patients with various degrees of pericardial effusion supporting its use as a quantitative measure of left-ventricular compression in patients with suspected cardiac tamponade.

[Peri-operative management in patients with thoracic aortic aneurysm complicated with cardiac tamponade]

We retrospectively summarized the peri-operative hemodynamic status and respiratory function in patients with thoracic aneurysms complicated with cardiac tamponade (Tamponade Group; n = 6) in comparison with patients complicated with hemorrhagic pericardial effusion without symptom of cardiac tamponade (Effusion Group; n = 10). There were no difference with regard to preoperative heart rate, pericardial effusion quantity, frequency of emergent operation and operation time. Preoperative hemodynamic status was worse in Tamponade Group than in Effusion Group. The cardiac indices of 12 h, 24 h, 48 h after operation in Tamponade Group were 2.60 +/- 0.60, 2.29 +/- 0.42, 1.95 +/- 0.33 l/min/m2 respectively, those were not different in Effusion Group. The differences between O2 tension in alveolar and arterial blood O2 tension (A-aDO2) and oxygenation indices (OI) of 12 h and 24 h after operation were significantly worse in Tamponade Group than in Effusion Group, but those of 48 h were not different. The operative mortality was 50% in Tamponade Group, and none in Effusion Group. It is very important to maintain hemodynamic status before operation, to perform complete repair (graft replacement) as early as possible and to care intensively after operation for thoracic aortic aneurysm complicated with cardiac tamponade.

Effects of systemic arterial hypoperfusion on splanchnic hemodynamics and hepatic arterial buffer response in pigs

The hepatic arterial buffer response (HABR) tends to maintain liver blood flow under conditions of low mesenteric perfusion. We hypothesized that systemic hypoperfusion impairs the HABR. In 12 pigs, aortic blood flow was reduced by cardiac tamponade to 50 ml. kg(-1). min(-1) for 1 h (short-term tamponade) and further to 30 ml. kg(-1). min(-1) for another hour (prolonged tamponade). Twelve pigs without tamponade served as controls. Portal venous blood flow decreased from 17 +/- 3 (baseline) to 6 +/- 4 ml. kg(-1). min(-1) (prolonged tamponade; P = 0.012) and did not change in controls, whereas hepatic arterial blood flow decreased from 2 +/- 1 (baseline) to 1 +/- 1 ml. kg(-1). min(-1) (prolonged tamponade; P = 0.050) and increased from 2 +/- 1 to 4 +/- 2 ml. kg(-1). min(-1) in controls (P = 0.002). The change in hepatic arterial conductance (DeltaC(ha)) during acute portal vein occlusion decreased from 0.1 +/- 0.05 (baseline) to 0 +/- 0.01 ml. kg(-1). min(-1). mmHg(-1) (prolonged tamponade; P = 0.043). In controls, DeltaC(ha) did not change. Hepatic lactate extraction decreased, but hepatic release of glutathione S-transferase A did not change during cardiac tamponade. In conclusion, during low systemic perfusion, the HABR is exhausted and hepatic function is impaired without signs of cellular damage.

Sac attack

Although cardiac tamponade remains uncommon, morbidity and mortality from cardiac tamponade are high. EMS providers must understand the numerous causes and prehospital management of cardiac tamponade. Proper identification of its signs and symptoms, followed by correct management, may save lives.