Electrical alternans in cardiac tamponade

Electrocardiograms in Critical Care Cardiology

Patients with critical illness may present with electrocardiogram (ECG) findings with bizarre QRS morphology or abnormal amplitude. This article provides ECG examples from such clinical scenarios and discusses their clinical characteristics and significance. (Level of Difficulty: Beginner.).

Clinical significance of 12 lead ECG changes in patients undergoing pericardiocentesis for cardiac tamponade

INTRODUCTION

The electrocardiogram (ECG) is one of the initial tests done in patients suspected of having a cardiac Tamponade. Historically the emphasis has been on low QRS voltage and electrical alternans, which lacks specificity and sensitivity respectively. Majority of these studies included patients with pericardial effusions without tamponade. Moreover, the influence of different therapeutic interventions such as pericardiocentesis on ECG variables has not been elucidated.

OBJECTIVE

To determine the clinical significance of 12 lead ECG changes in patients undergoing pericardiocentesis for cardiac tamponade.

METHODS

144 patients underwent Echo guided pericardiocentesis for cardiac tamponade at a tertiary care hospital over a period of 7 years. We compared 19 EKG variables pre and post procedure.

RESULTS

Low voltage was detected in only 31 patients (29%) with 19 (18%) patients having persistent low voltage (p value = 0.0047) after the pericardiocentesis. Electrical alternans was only observed in 25 patients (23%), and persisted in 10 patients (10%) following pericardiocentesis. None of the other EKG variables measured changed reliably post procedure.

CONCLUSION

We found that although electrical alternans and low voltage were associated with cardiac tamponade, none of the ECG variables were highly sensitive or specific for the diagnosis, reproducibly changed after drainage or predicted recurrent effusion post-pericardiocentesis.

Images of the month 2: Electrocardiographic QRS alternans caused by gastric volvulus

QRS electrical alternans is characterised by alternating amplitude of the QRS complexes, and is well-documented in cardiac conditions such as pericardial effusion. We describe a case of QRS alternans in a patient with gastric volvulus.

Total electrical alternans in a patient with malignant pericardial tamponade

We present a case of a 59-year-old man with acute abdominal pain and progressive shortness of breath. A focused assessment with sonography for trauma scan showed free fluid in the hepatorenal recess and in the recto-uterine recess. Later, due to clinical deterioration and the differential possibility of a pulmonary embolism or aortic dissection, a CT scan was performed which revealed large pericardial effusion. This, together with a dilated vena cava inferior and portal system, raised the suspicion of cardiac tamponade. The diagnosis was confirmed by transthoracic echocardiography (TTE). In retrospect, the ECG at admission showed a sinus tachycardia, low-voltage QRS complexes and a total electrical alternans corresponding with the swinging heart seen on TTE. An electrical alternans on ECG is an important diagnostic clue but is often missed, causing an unnecessary delay to proper diagnostic and therapeutic measures.

Echocardiographic Applications of M-Mode Ultrasonography in Anesthesiology and Critical Care

Proficiency in echocardiography and lung ultrasound has become essential for anesthesiologists and critical care physicians. Nonetheless, comprehensive echocardiography measurements often are time-consuming and technically challenging, and conventional 2-dimensional images do not permit evaluation of specific conditions (eg, systolic anterior motion of the mitral valve, pneumothorax), which have important clinical implications in the perioperative setting. M-mode (motion-based) ultrasonographic imaging, however, provides the most reliable temporal resolution in ultrasonography. Hence, M-mode can provide clinically relevant information in echocardiography and lung ultrasound-driven approaches for diagnosis, monitoring, and interventional procedures performed by anesthesiologists and intensivists. Although M-mode is feasible, this imaging modality progressively has been abandoned in echocardiography and is often underutilized in lung ultrasound. This article aims to comprehensively illustrate contemporary applications of M-mode ultrasonography in the anesthesia and critical care medicine practice. Information presented for each clinical application will include image acquisition and interpretation, evidence-based clinical implications in the critically ill and surgical patient, and limitations. The present article focuses on echocardiography and reviews left ventricular function (mitral annular plane systolic excursion, E-point septal separation, fractional shortening, and transmitral propagation velocity); right ventricular function (tricuspid annular plane systolic excursion, subcostal echocardiographic assessment of tricuspid annulus kick, outflow tract fractional shortening, ventricular septal motion, wall thickness, and outflow tract obstruction); volume status and responsiveness (inferior vena cava and superior vena cava diameter and respiratory variability [collapsibility and distensibility indexes]); cardiac tamponade; systolic anterior motion of the mitral valve; and aortic dissection.

P-wave alternans in a patient with hyponatremia

We describe an unusual electrocardiographic (ECG) case of an alternating P-wave configuration that spares other ECG components. Hyponatremia due to chronic indapamide use was proposed as a plausible cause of this ECG phenomenon because its correction led to the recovery of a steady P-wave morphology.

The importance of an ECG: back to basics

A 48-year-old man presented to accident and emergency with syncope on a background history of 3 weeks of increasing shortness of breath. He collapsed at home prompting admission. He was a smoker with a 30-pack-year history. On examination, he was found to be tachypnoeic and hypoxic, with a raised JVP and quiet heard sounds. He was haemodynamically stable and a chest x-ray showed right upper-lobe collapse. His resting ECG demonstrated electrical alternans prompting urgent referral to the cardiologist for echocardiography. This revealed a large pericardial effusion with evidence of right ventricular diastolic collapse. In view of this, he underwent urgent pericardiocentesis. A subsequent CT scan showed bilateral pleural effusions and multiple lung nodules. Both pericardial and pleural fluid cytology were reported as metastatic non-small cell adenocarcinoma. The pericardial fluid continued to reaccumulate requiring a pericardial window. He was referred to the oncology team for palliative chemotherapy.

Diagnosis and management (by subxiphoid pericardiotomy) of large pericardial effusions causing cardiac tamponade

To determine the clinical features, course and outcome of patients with cardiac tamponade, 57 consecutive patients with new, large pericardial effusions were prospectively studied. Twenty-five patients (44%) developed cardiac tamponade with venous hypertension and a pulsus paradoxus greater than 10 mm Hg. Electrocardiography, radiographic studies and echocardiography did not differentiate patients with and without tamponade. All 57 patients underwent thorough diagnostic evaluation followed by subxiphoid pericardial biopsy and drainage. A diagnosis was obtained in 53 patients (93%). Collagen vascular disease was significantly more frequent in the 25 patients with than in the 32 without cardiac tamponade (24 vs 3%; p less than 0.05). The frequency of malignant and uremic effusions was equal in both groups, whereas radiation-induced effusions seldom produced tamponade. At 1-year follow-up, 3 patients (12%) with tamponade had recurrent effusions, and 1 needed reoperation. This was not significantly different from the 32 patients without tamponade. Twelve-month mortality was also similar in both groups (36 vs 44%). This prospective series disclosed several unexpected findings: (1) Cardiac tamponade occurred in almost 50% of patients with new large pericardial effusions; (2) both malignancy and collagen vascular disease occurred with equal frequency as etiologies, whereas radiation-induced tamponade was unusual; (3) thorough clinical evaluation resulted in few idiopathic etiologies; and (4) subxiphoid pericardiotomy was effective for both diagnosis and therapy of tamponade.

Cardiac tamponade due to malignant pericardial effusion in breast cancer: a case report

Cardiac tamponade resulting from malignant pericardial effusion is an uncommon initial presentation of various extracardiac malignancies. Only twenty-nine cases of extracellular malignancies with this initial presentation have been previously published. Lung carcinoma leads as the most common malignancy involved, followed by carcinoma of the stomach, pancreas, kidney and ovary, mediastinal rhabdomyosarcoma, malignant lymphoma and leukemia. This report describes a case of breast carcinoma in a 47-year-old woman who initially presented with cardiac tamponade. To the best of the authors' knowledge, no similar case has even been reported in the literature.

Cardiac tamponade in medical patients

We reviewed the cases of 56 medical patients wih cardiac tamponade who were treated at the University of Cincinnati. A paradoxic arterial pulse was critical in the diagnosis because most patients did not have a small quiet heart, and blood pressure was often well maintained. Fifty-two of 55 patients had enlarged cardiac silhouette by chest radiogram; heart sounds were diminished in 19 patients; arterial systolic pressure was greater than or equal to 100 mm Hg in 35, and arterial pulse pressure was greater than or equal to 40 mm Hg in 27. Echocardiograms in 23 patients showed abnormally increased right ventricular dimensions and decreased left ventricular dimensions during inspiration, except in one patient with left ventricular dysfunction. The causes of cardiac tamponade were metastatic tumor in 18 patients, idiopathic pericarditis in eight and uremia in five; five cases of tamponade occurred after heparin administration in acute cardiac infarction. Myxedema and dissecting aneurysm each caused tamponade in two patients. Pericardiocentesis relieved tamponade initially in 40 of 46 patients; however, two suffered fatal complications. Pericardial resection was done in 18, including 12 of these 46.

Pericardial effusion and electrical alternans: echocardiographic assessment

Clinical diagnosis of pericardial effusion is often difficult, and assessment of the effects of effusion on cardiac hemodynamics is often imprecise. Electrical alternans is a reasonably specific ECG indicator of the presence of a large effusion and imminent or actual cardiac tamponade. If echocardiography verifies the presennce of pericardial fluid and shows abnormal cardiac motion, a diagnosis of cardiac tamponade can be made without further, more invasive, studies.

Alternans of the ST segment in Prinzmetal's angina

Alternans of the elevated ST segment (STEA) was found in 8 of 21 patients (38%) with Prinzmetal's variant angina. In addition to STEA, all eight patients had varying cardiac arrhythmias: multiple premature ventricular depolarizations in eight, ventricular tachycardia in five, and ventricular fibrillation in three. There was no consistent temporal relationship between the occurrence of STEA and the cardiac arrhythmias. Alternans occurred during periods when no arrhythmias were present. All eight patients underwent coronary angiography. Spontaneous coronary artery spasm was documented angiographically in three patients including two who had minimal or no coronary atherosclerotic disease. Six patients had severe, fixed, occlusive coronary artery disease. Possible mechanisms for STEA include: 1) failure of regions of myocardium to depolarize on alternate beats due to variation in conduction and refractoriness between ischemic and nonischemic zones of myocardium, and 2) electrical alternans of the transmembrane action potential during phase 2 and 3 (repolarization) caused by changes in the rate and extent of electrolyte transfer across cell membranes during ischemia. It is postulated that STEA is an electrocardiographic sign in the surface ECG of a dysequilibrium of refractory periods during ischemia and reflects an unstable electrical state of the myocardium.