Cardiac risk stratification of patients with symptomatic spinal stenosis.

The leading cause of death in the perioperative period after noncardiac surgery is a cardiac event. As the number of lumbar surgeries performed in patients older than 65 years of age continues to increase, this patient population with neurogenic claudications is an at risk group for a cardiac event because of their age and associated cardiac risk factors. The authors attempted to document by means of cardiac chemical stress testing, the prevalence of silent ischemic cardiac disease in patients with neurogenic claudication who were candidates for elective lumbar surgery. Eleven of 140 patients (8%) had induced cardiac wall abnormalities on stress testing, indicating myocardial ischemia. The only risk factors associated with cardiac ischemia were smoking and history of heart disease. It is recommended that dobutamine stress echocardiography be performed in patients undergoing elective spinal surgery for symptomatic spinal stenosis if they have a history of previous heart disease, smoking, or both.

Two-dimensional echocardiography and Doppler ultrasound in managing obstetric patients.

OBJECTIVE: To test the usefulness of ultrasound-derived measurements of intracardiac filling pressures and cardiac performance in the noninvasive management of obstetric patients with an indication for hemodynamic monitoring. METHODS: We included patients with oliguria unresponsive to crystalloid boluses, with hypertension unresponsive to hydralazine, and at high risk for pulmonary edema who were determined to be candidates for invasive monitoring. They were first studied with two-dimensional echocardiography and Doppler ultrasound using a technique previously validated at our institution. Cardiac dimensions, filling pressures, and function were assessed at the bedside. Subsequently, management decisions were made based on these findings. RESULTS: Fourteen patients were studied. Two received a pulmonary artery catheter after noninvasive evaluation indicated a need for continuous monitoring. The 12 patients managed without the need for a pulmonary artery catheter included women with intractable hypertension (one patient), pulmonary edema (two patients), complex cardiac lesions (two patients), oliguria (five patients), intractable hypertension and oliguria (one patient), and unexplained dyspnea with peripheral arterial oxygen desaturation (one patient). Although some patients received as much as 8 L of crystalloid, none developed pulmonary edema or left ventricular failure. In all 12 cases, the ultrasound monitoring allowed successful noninvasive management of the patient. CONCLUSION: This pilot study suggests that two-dimensional echocardiography and Doppler examination may be an effective alternative to invasive monitoring in the management of selected pregnant patients.

Cardiac systolic and diastolic function at rest and exercise in subclinical hypothyroidism: effect of thyroid hormone therapy.

Cardiac atrial and ventricular parameters were determined by Doppler two-dimensional echocardiography at rest and exercise in 8 patients with subclinical hypothyroidism (SCH) (6 women and 2 men; age range: 28-48 years) before and 3 months after achievement of a euthyroid state with incremental adjustment of L-thyroxine therapy. None of the patients had known heart disease. At 3 months of L-thyroxine therapy, TSH levels decreased from 14.8 +/- 9.4 mIU/L to 3.0 +/- 1.5 mIU/L and FTI increased from 7.1 +/- 1.8 to 8.1 +/- 1.9. The cardiac studies were performed at rest, and during incremental exercise load (50, 100, 150 W workload) on a Quinton exercise bicycle. No significant differences were found between the subclinical hypothyroid and euthyroid states in systolic blood pressure at rest (104.8 +/- 12.3 vs 105 +/- 10.1 mm Hg) and exercise (158 +/- 24.9 vs 158.5 +/- 20.9 mm Hg) or diastolic blood pressure at rest (70 +/- 4.7 vs 69 +/- 5.7 mm Hg) and exercise (86 +/- 11.4 vs 89.2 +/- 7.3 mm Hg). All echocardiographic atrial and ventricular parameters were similar before and during L-thyroxine therapy with the exception of a small but significant change in left ventricular diastolic dimension (4.5 +/- 0.3 vs 4.8 +/- 0.4 cm; p < 0.05). All Doppler parameters were not significantly affected by L-thyroxine therapy with the exception of preejection period at stage III exercise (51 +/- 17 vs 39 +/- 13 msec; p < 0.05). Preejection period at other stages of exercise showed trends toward similar differences between subclinical hypothyroidism and euthyroidism, but the differences were not statistically significant. We conclude that the cardiac structure and function overall remains for practical purposes normal in subclinical hypothyroidism. However, the latter may be responsible for a mild prolongation of the preejection period during exercise and a slightly smaller left ventricular diastolic dimension at rest, changes that may not be of clinical significance in patients without underlying heart disease.

Quantitative echocardiographic assessment of left ventricular function in critically ill obstetric patients: a comparative study.

OBJECTIVE: Our purpose was to compare different echocardiographic methods to quantitate maternal ventricular function. STUDY DESIGN: Eleven critically ill obstetric patients requiring invasive monitoring and M-mode and two-dimensional Doppler echocardiographic studies were retrospectively studied. Ventricular volumes and ejection fraction derived from multiple methods were computed and compared with analysis of variance and Newman-Keuls tests. RESULTS: Two M-mode studies could not be analyzed. M-mode and two-dimensional estimates of stroke volume were similar to the previously validated Doppler stroke volume values of these 11 patients. End-diastolic volume estimates were similar. There was no difference in ejection fraction for the five different two-dimensional Doppler methods used (66%, 66%, 67%, 63%, and 63%). CONCLUSION: Left ventricular function is reliably calculated in pregnant women by a number of different echocardiographic techniques. The ability to combine echocardiographic techniques is helpful when any single method does not provide all of the information required.

Comparison of echocardiographic assessment of cardiac hemodynamics in the intensive care unit with right-sided cardiac catheterization.

Estimation of left ventricular filling pressure and cardiac index is important in the management of patients requiring right heart catheterization. Doppler echocardiography can provide a noninvasive measure of these parameters, but its accuracy in individual measurements, predicting hemodynamic subgroups, and in tracking serial changes in critically ill patients remains to be elucidated. Left ventricular filling pressure and cardiac index were assessed in 49 critically ill patients requiring right heart catheterization and Doppler echocardiographic studies. Two or more serial studies were performed in 18 of these subjects. Patients were placed into 1 of 4 hemodynamic subgroups for each technique based on the acquired hemodynamic parameters. Left ventricular filling pressure and cardiac index by Doppler echocardiography and right heart catheterization were similar (21 +/- 8 vs 20 +/- 8 mm Hg; 3.0 +/- 1.2 vs 2.9 +/- 1.2 L/min/m2, respectively) and correlated well with each other (left ventricular filling pressure, r = 0.88; cardiac index, r = 0.92). The Doppler technique accurately placed 73 of 76 studies into the correct hemodynamic subgroup. The noninvasive technique also reliably tracked serial hemodynamic measurements. We conclude that Doppler echocardiography accurately assesses left heart hemodynamics in critically ill patients. Since this technique can be readily acquired, it can be ideal for the rapid assessment of hemodynamic parameters in critically ill patients, especially when right heart catheterization is delayed or is problematic.

Inaccurate noninvasive mitral valve area calculation during pregnancy.

OBJECTIVE: To compare two different Doppler echocardiographic techniques for the assessment of the transmitral area in pregnant patients with native mitral valve stenosis or prosthetic mitral valves. METHODS: Eight consecutive gravid women with prosthetic mitral valves or obstructive native mitral valve disease were evaluated using both the pressure half-time and the continuity equation Doppler echocardiographic methods. Heart rate, cardiac output, and transmitral valve gradient and area were calculated. These studies were repeated postpartum in five women. Differences between the two methods were assessed by characterizing the absolute differences between the mean and standard deviation and by paired t tests. Linear regression analysis was also applied. RESULTS: For the five women who also had postpartum studies, antepartum data were similar to those of the full set of eight patients. Postpartum heart rate, cardiac output, and transvalvular gradient were lower than antepartum measurements. Calculations using the continuity equation yielded comparable antepartum and postpartum estimates of transmitral areas (1.31 +/- 0.41 versus 1.32 +/- 0.44 cm2, respectively, r = 0.96). These estimates were also consistent with the initial clinical presentation. In contrast, antepartum transmitral valve areas calculated using the pressure half-time technique (2.67 +/- 0.61 cm2) were markedly higher than postpartum (1.94 +/- 0.58 cm2). The correlation between the estimates of antepartum valve area given by the two methods was not statistically significant (r = 0.02). In contrast, there was excellent postpartum correlation of transmitral area between the methods (r = 0.99), despite a significant difference (P < .001) in the transmitral area calculated with each technique. CONCLUSIONS: The results indicate that Doppler echocardiographic estimates of the transvalvular area using the continuity equation technique during pregnancy are valid. In contrast, estimates of area using the pressure half-time technique in pregnant patients are dubious and could result in life-threatening consequences.

Massive hemoptysis in Takayasu's arteritis during pregnancy.

Takayasu's arteritis is an uncommon condition affecting predominantly young women. Because the disorder affects women in childbearing age, it may be recognized the first time during pregnancy. Various cardiovascular events may occur in the perinatal period. We describe a patient with Takayasu's arteritis who presented with massive hemoptysis. To our knowledge, this manifestation has not been documented previously.

Rapid echocardiographic assessment of left and right heart hemodynamics in critically ill obstetric patients.

OBJECTIVE: Our purpose was to compare noninvasive two-dimensional and Doppler echocardiography and right heart catheterization with a pulmonary artery catheter in the estimation of stroke volume, cardiac output, cardiac index, left ventricular filling pressure, pulmonary artery systolic pressure, and right atrial pressure in a heterogeneous group of critically ill obstetric patients. STUDY DESIGN: Eleven critically ill obstetric patients requiring invasive monitoring for clinical management were prospectively studied. Simultaneous Doppler and pulmonary artery catheter readings of stroke volume, cardiac output, cardiac index, left ventricular filling pressure, pulmonary artery systolic pressure, and right atrial pressure were acquired. Mean +/- SD or median and range, as appropriate, of each parameter were compared, and data for all parameters were subjected to regression analysis. A two-tailed p value < 0.05 was regarded as significant. RESULTS: There was no significant difference between the two techniques in the estimation of cardiac index, intracardiac pressures, or pulmonary artery systolic pressure. There was a good correlation between the two methods for stroke volume (R2 = 0.98), cardiac output (R2 = 0.98), cardiac index (R2 = 0.96), left ventricular filling pressure (R2 = 0.79), pulmonary artery systolic pressure (R2 = 0.85), and right atrial pressure (R2 = 0.86). CONCLUSION: Two-dimensional and Doppler echocardiography allow rapid, reliable, noninvasive assessment of hemodynamic parameters in critically ill obstetric patients and may give the clinician valuable information that may influence therapeutic and clinical management.

Role of spin echo and cine magnetic resonance imaging in presurgical planning of heterotaxy syndrome. Comparison with echocardiography and catheterization.

BACKGROUND: Patients with heterotaxy syndrome frequently have complex congenital cardiac and noncardiac malformations requiring detailed diagnostic evaluation by noninvasive as well as invasive imaging modalities for management planning. Recent advances in magnetic resonance imaging (MRI) techniques allow detailed delineation of cardiovascular anatomy and blood flow in young infants with rapid heart rates. The present study was undertaken to prospectively evaluate the role of MRI in the presurgical evaluation of patients with heterotaxy syndrome. METHODS AND RESULTS: Between January 1 and December 31, 1992, 14 consecutive patients with heterotaxy syndrome and complex congenital heart disease were enrolled in a prospective protocol. After evaluation by echocardiography and cardiac catheterization, a tentative management plan was recorded. Subsequently, a MRI study was performed and surgical planning was reevaluated. MRI was found to be comparable to echocardiography in terms of length of examination and sedation requirements. Surgical planning was altered in four patients because MRI provided additional data not evident on echocardiography and catheterization. Comparison of diagnostic yield between echocardiography, catheterization, and MRI showed that MRI is superior to echocardiography and often to catheterization in delineation of systemic and pulmonary venous anatomy and their relation to mediastinal structures. When the anatomic and hemodynamic data obtained by echocardiography and MRI were considered together, cardiac catheterization data were necessary only to determination of pulmonary vascular resistance before Fontan operation. CONCLUSIONS: MRI provides excellent anatomic and functional information that in some patients was not available by echocardiography or catheterization. Combined with echocardiography, MRI provides the high-quality diagnostic information necessary for management planning in most patients with heterotaxy syndrome. Cardiac catheterization is indicated when determination of pulmonary vascular resistance is necessary for decision making or when an interventional procedures is indicated.

Comparison of gradient echo with spin echo magnetic resonance imaging and echocardiography in the evaluation of major aortopulmonary collateral arteries.

This study compared gradient echo magnetic resonance imaging, spin echo magnetic resonance imaging, echocardiography, and echocardiography with x-ray cineangiography in the evaluation of major aortopulmonary collateral arteries. Twelve patients (ages 9 months to 35 years, mean 11 +/- 11 years) with known or suspected major aortopulmonary collateral arteries were studied. The aortic insertion and proximal course of 29 major aortopulmonary collateral arteries demonstrated by x-ray contrast angiography were shown in all 29 cases by gradient echo magnetic resonance imaging but in only 23 of the 29 cases by spin echo magnetic resonance imaging. Color Doppler-echocardiography detected aortopulmonary collateral arteries in four patients but did not define the proximal course or distal anatomy. Gradient echo images of distal aortopulmonary collateral anatomy were qualitatively superior to spin echo images. The contrast-to-noise ratio between the vessel lumen and adjacent lung was greater for gradient echo (6.06 +/- 2.91) than for spin echo (1.45 +/- 1.13)(p < 0.05). Gradient echo magnetic resonance imaging is a useful method for identification and characterization of aortopulmonary collateral arteries in patients of all ages and is superior to spin echo magnetic resonance imaging and echocardiography.

Transcatheter occlusion of patent ductus arteriosus in adults.

This study examines whether transcatheter closure of a patent ductus arteriosus (PDA) using a Rashkind PDA occluder device is safe and effective in adults, or if adults have complications not sited in children owing to prolonged aorticopulmonary communication, high surgical risks or calcified PDAs. Fifteen patients aged 22 to 76 years (mean 42 +/- 14) were referred for transcatheter PDA occlusion. Exercise intolerance was the most frequent clinical manifestation. Eleven of 15 patients had surgical risk factors that included left ventricular failure (n = 10), biventricular failure (n = 1), elevated pulmonary pressures (n = 1), and a calcified PDA (n = 5). Twelve millimeter devices were placed in 4 PDAs < or = 3 mm in diameter; 17 mm devices were placed in 11 PDAs 3 to 6 mm in diameter. Seven (47%) were occluded angiographically shortly after device placement; another 5 PDAs (33%) were occluded echocardiographically within 24 hours of the procedure. Completed occlusion in this time interval was more likely to occur in PDAs < 5 mm in diameter (p = 0.0009). Of the 3 remaining PDAs with follow-up ranging from 9 to 38 months, 2 have demonstrated gradual diminution of shunting and have trivial leaks by color/Doppler flow. The other patient with a residual PDA has no ductal flow after placement of a second device. No complications related to device implantation or closure of the PDA occurred in any patient. No complications were reported in the follow-up patients who received evaluation (14 of 15 patients; range 1 to 38 months).(ABSTRACT TRUNCATED AT 250 WORDS)

Termination of supraventricular tachycardia with intravenous adenosine in a pregnant woman with Wolff-Parkinson-White syndrome.

BACKGROUND: Pregnancy is associated with an increased frequency of arrhythmias in women with Wolff-Parkinson-White syndrome. We describe the use of intravenous (IV) adenosine for the acute termination of a narrow complex tachycardia in a pregnant patient with this syndrome. CASE: A 26-year-old woman with known Wolff-Parkinson-White syndrome presented with dizziness, palpitations, and a narrow complex supraventricular tachycardia. We used IV adenosine to convert the arrhythmia to a normal sinus rhythm. During labor, the patient again developed a narrow complex supraventricular tachycardia, and fetal monitoring revealed recurrent deep variable decelerations. Intravenous adenosine resulted in conversion to sinus rhythm and restoration of the fetal heart rate to normal. Cesarean delivery produced a healthy male infant. CONCLUSIONS: Adenosine is effective in rapidly terminating maternal narrow complex tachyarrhythmias before and during delivery in women with Wolff-Parkinson-White syndrome. It can also treat fetal bradycardia resulting from the maternal arrhythmia.

Magnetic resonance velocity measurements in small arteries. Comparison with Doppler ultrasonic measurements in the aortas of normal rabbits.

RATIONALE AND OBJECTIVES: Magnetic resonance imaging (MRI) can be used to measure motion. This study compares MRI blood flow velocity measurements to Doppler ultrasound velocity measurements in an animal model. MATERIALS AND METHODS: Blood flow in the abdominal aortas of nine normal rabbits was measured using 16-frame, velocity-resolved MRI and Doppler ultrasound. The MRI data were processed into velocity spectra to aid in their interpretation. RESULTS: Maximum velocity measurements made by range-gated Doppler ultrasound were predicted by the maximum velocity values derived from MR velocity spectra with a slope of 0.861, an intercept of -2.78 cm/second, and an R-value of 0.935 in 70 measurements. CONCLUSIONS: Despite the longer time required for the MR measurement, the MR velocity measurement may be useful in the assessment of deep vessels or those obscured by other structures, which are difficult to measure with ultrasound.

Does cocaine cause coronary vasospasm in chronic cocaine abusers? A study of coronary and systemic hemodynamics.

The pathogenesis of acute myocardial ischemia or infarction following cocaine abuse is not known. Cocaine causes an increase in circulating catecholamines. Therefore alpha-adrenergic mediated focal or generalized coronary artery spasm has been presumed to be the likely mechanism to induce ischemia. However, coronary vasospasm in chronic cocaine abusers has not been demonstrated angiographically. Moreover, it has been observed that patients commonly manifest ischemic changes hours up to a week after abusing cocaine. In order to evaluate direct effects of cocaine on coronary vasculature, 6 chronic cocaine abusers admitted with prolonged chest pain and electrocardiographic ST- and T-wave changes were studied. Cocaine administered intravenously (maximum 32 mg) produced subjective sensation of central nervous stimulation (the "high") in all patients. However there was no significant change in coronary artery diameter (assessed by computer-assisted quantitative technique), myocardial perfusion (assessed by contrast echocardiography) or left ventricular wall motion (assessed by two-dimensional echocardiography) as compared with the baseline values. Coronary sinus flow (thermodilution) showed an upward trend, a probable reflection of a significant increase in cardiac output (average 62%, p less than 0.007). Despite a significant elevation in heart rate (average 56%, p less than 0.007), mean systemic arterial pressure (average 12%, p less than 0.05) and rate-pressure product (average 69%, p less than 0.005), no symptomatic or acute electrocardiographic changes were observed. It is concluded that recreational doses of cocaine do not cause focal or generalized coronary vasospasm or reduced myocardial perfusion in patients who present with chest pain temporally related to cocaine.(ABSTRACT TRUNCATED AT 250 WORDS)

An electrocardiograph-respiration gating device for MR studies.

A versatile gating device for magnetic resonance (MR) spectroscopy and imaging is presented. The device uses electrocardiograph (ECG) and respiration signals as input, applies appropriate signal conditioning, and generates control signals for ECG, respiration, or combined gating studies. In the combined ECG and respiration mode, in conjunction with a proper MR pulse program, one can acquire MR data gated by the ECG signal within a selected window of the respiration cycle, while maintaining a steady level of magnetization saturation during the remainder of the respiration cycle, by gating the radio-frequency excitation with the ECG while inhibiting data acquisition.

Resolution of ventricular tachycardia and endocardial tuberculoma following antituberculosis therapy.

A 23-year-old woman presented with sustained ventricular tachycardia and was found to have an endocardial mass by echocardiography and by magnetic resonance imaging. The diagnosis of cardiac endocardial tuberculoma was made, and she was treated with antituberculous therapy and an antiarrhythmic drug for one year. After a year, the mass was no longer present, and with all antiarrhythmic medications stopped, ventricular tachycardia could no longer be induced by electrophysiologic study. There has been no clinical recurrence.

Assessment of experimental pericardial effusion using nuclear magnetic resonance imaging techniques.

An experimental canine model of pericardial effusion was designed to validate previous clinical nuclear magnetic resonance imaging (NMR) studies. Saline (n = 7), serum (n = 4), blood (10% hematocrit [n = 5]; 20% hematocrit [n = 5]), and lipid (n = 4) effusions were chosen to resemble: (1) transudative/exudative, (2) nonhemorrhagic/hemorrhagic, and (3) chylous effusions, respectively. There was a linear correlation between the infused volume and the pericardial/epicardial distance measurements on the nuclear magnetic resonance images. Hemorrhagic and nonhemorrhagic exudative effusions were distinguished from transudative effusions by the low signal intensity of transudative effusions images obtained at a TR (repetition time) of 400 and 800 msec. Nonhemorrhagic effusions had significantly lower effusion-to-myocardial signal intensity ratio at TR of 400 msec than did hemorrhagic effusions. Differences in hematocrit were not appreciated qualitatively or quantitatively. Compared with other effusion types, only chylous effusions were hyperintense to myocardium at a TR of 400 msec. Chylous effusions were further uniquely characterized by a decreasing effusion-to-myocardial signal intensity ratio with increasing TR. These experimental findings corroborate the findings of earlier clinical reports and suggest that NMR can provide important assistance in the evaluation of pericardial effusions.