Another measurement of cardiac output: is it truly needed?
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Animals↗
Biomedical subjects
R A Nishimura
Publications and source records attributed to R A Nishimura.
Palliative percutaneous aortic balloon valvuloplasty before noncardiac operations and invasive diagnostic procedures.
Percutaneous aortic balloon valvuloplasty (PABV) is useful in palliating symptoms of severe aortic stenosis in patients who are not candidates for aortic valve replacement. In 15 patients who had severe aortic stenosis and a contraindication to aortic valve replacement, PABV was performed before a noncardiac procedure, in an attempt to improve their hemodynamics and reduce the risks associated with the operation or preoperative diagnostic test. The mean aortic gradient was reduced from 58.1 +/- 6.0 mm Hg to 32.2 +/- 4.0 mm Hg (P less than 0.0002), and the aortic valve area was increased from 0.49 +/- 0.04 cm2 to 0.85 +/- 0.10 cm2 (P less than 0.0002). Complications associated with PABV included left ventricular perforation in three patients (which resulted in death in one of them), transient congestive heart failure in one, and development of femoral pseudoaneurysms in one. After PABV, nine patients underwent the planned surgical procedure under general anesthesia without complications. Five patients underwent surgical diagnostic procedures after PABV that resulted in a change in treatment strategy. Three of these patients required no further treatment, and two required resection of the colon for bleeding, which was preceded by aortic valve replacement. This study demonstrates that PABV may be useful in reducing the risks of noncardiac procedures in selected patients with severe aortic stenosis who are otherwise not candidates for aortic valve replacement.
Aged↗
Assessment of diastolic function of the heart: background and current applications of Doppler echocardiography. Part I. Physiologic and pathophysiologic features.
In the past, evaluation of the myocardium has been limited to examining systolic function of the heart. Recently, however, investigators have demonstrated that abnormalities of diastolic function of the heart provide important contributions to the signs and symptoms experienced by patients with heart disease. In addition, abnormalities of diastolic function may precede abnormalities of systolic function in the early stages of disease. Diastolic filling of the heart, however, is a complex sequence of interrelated events. In order to understand diastolic function, each of these factors contributing to filling of the heart must be examined. They include relaxation, passive compliance, atrial contraction, erectile effect of the coronary arteries, viscoelastic properties, ventricular interaction, and pericardial restraint--all of which are interrelated. In addition, diastolic factors are affected by changes in loading conditions and contractility, and they demonstrate nonuniformity in time and space. This report provides an overview of these various factors from the clinical perspective, based on studies involving the isolated papillary muscle and the isolated heart as well as basic clinical studies.
Animals↗
Assessment of diastolic function of the heart: background and current applications of Doppler echocardiography. Part II. Clinical studies.
Evaluation of diastolic filling of the heart has been difficult because of its complexity and the numerous interrelated contributing factors. Previous determinations have depended on high-fidelity, invasive measurements of instantaneous pressure, volume, mass, and wall stress, which could not be done on a routine clinical basis. With the advent of Doppler echocardiography, intracardiac blood flow velocities can now be noninvasively assessed. For application of this technique to evaluation of diastolic function in patients with heart disease, it is necessary to understand what the Doppler-derived variables represent. It is also necessary to know how they are affected by changes in loading conditions and changes in myocardial relaxation. In this review, we provide an interpretation of the mitral valve, tricuspid valve, and systemic and pulmonary venous inflow velocities in the normal patient and in various disease states.
Blood Flow Velocity↗
Parameters affecting occurrence of paradoxical air embolism.
The effects of different patterns of ventilation and intravascular volume infusion on the occurrence of paradoxical air embolism (PAE) were evaluated in 15 pigs with a surgically created atrial septal defect (ASD). A balloon atrial septostomy was created transvenously in anesthetized pigs (mean diameter 8.6 mm +/- 1 mm). Monitoring included transesophageal echocardiography (TEE) of the right and left heart, ECG, EEG, direct arterial pressure, right and left atrial pressures (RAP and LAP), pulmonary artery pressure, and pulmonary capillary wedge pressure (PCWP). With the animal in a head up tilt, air was infused into the superior vena cava at a rate of 0.27 ml.kg-1.min-1 for 6 min or until PAE was identified on the TEE. Four situations were studied--intermittent positive pressure ventilation (IPPV), intermittent positive pressure ventilation with 10 cm H2O positive end-expiratory pressure (PEEP), spontaneous ventilation, and IPPV following infusion of 500 ml hetastarch. The incidence of PAE was not different in any of the four situations. Release of PEEP resulted in an increase in the amount of PAE or new PAE in nine of 14 animals. PAE occurred both with and without mean RAP exceeding mean LAP and the incidence of PAE was not significantly different based on the atrial pressure gradient. In situations during which the mean LAP remained greater than mean RAP throughout the venous air infusion and PAE occurred, transient reversal of the right to left atrial pressure gradient during a portion of each cardiac cycle was demonstrated.
Animals↗
Failure of preoperative echo testing to prevent paradoxical air embolism: report of two cases.
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Adult↗
Continuous wave Doppler echocardiographic measurement of prosthetic valve gradients. A simultaneous Doppler-catheter correlative study.
Studies correlating prosthetic valve gradients determined by continuous wave Doppler echocardiography with gradients obtained by cardiac catheterization have, to date, been limited to patients with mitral and tricuspid prostheses or have compared nonsimultaneous measurements. Simultaneous Doppler and catheter pressure gradients in 36 patients (mean age, 63 +/- 13 years) with 42 prosthetic valves (20 aortic, 20 mitral, one tricuspid, and one pulmonary) were studied. Catheter gradients were obtained using a dual-catheter technique. The simultaneous pressure tracings and Doppler flow velocity profiles were digitized at 10-msec intervals to derive the corresponding maximal and mean gradients. The correlation between the maximal Doppler gradient and the simultaneously measured maximal catheter gradient was 0.94 (SEE = 6), and that between the Doppler gradient and the simultaneously measured mean catheter gradient was 0.96 (SEE = 3). There were no significant differences in correlation between gradients for the 32 mechanical valves (maximal gradients: r = 0.95, SEE = 6; mean gradients: r = 0.96, SEE = 3) and the 10 bioprosthetic valves (maximal gradients: r = 0.89, SEE = 6; mean gradients: r = 0.93, SEE = 3). In patients with mitral prostheses, Doppler gradients correlated well with the corresponding catheter gradients obtained with direct measurement of left atrial pressure (maximal gradients: r = 0.96, SEE = 2; mean gradients: r = 0.97, SEE = 1.2). A close correlation between corresponding Doppler and catheter gradients also was found in patients with aortic prostheses (maximal gradients: r = 0.94, SEE = 6; mean gradients: r = 0.94, SEE = 3). Thus, continuous wave Doppler echocardiography can accurately predict the pressure gradient across prosthetic valves.
Aged↗
Clinical follow-up after percutaneous aortic balloon valvuloplasty.
Percutaneous aortic balloon valvuloplasty has been applied in a growing number of patients with severe symptomatic calcific aortic stenosis. Follow-up data from these patients have not been well characterized. In 88 patients (mean age, 80 +/- 8 years) who underwent percutaneous aortic balloon valvuloplasty, the average initial aortic valve area was 0.48 +/- 0.20 cm2, and it increased to 0.74 +/- 0.26 cm2 after dilation. The average duration of follow-up in survivors was 7.8 months. Actuarial survival at 6 and 12 months was 75% and 63%, respectively. Factors associated with subsequent death included more severe impairment from heart failure at baseline, smaller initial aortic valve area, smaller final aortic valve area, low baseline cardiac output, and low ejection fraction. Among the surviving patients, 50% had no cardiac symptoms, and 85% had improved symptoms from congestive heart failure. Percutaneous aortic balloon valvuloplasty is associated with continued increased mortality during follow-up, although symptomatic improvement in survivors is good. Percutaneous aortic balloon valvuloplasty can be considered a palliative approach for severely symptomatic patients at high risk for aortic valve operation or patients with a limited life span due to other medical problems, but it is not indicated in patients at acceptably low risk for aortic valve replacement.
Aged↗
Blood velocity measurements during selective coronary angiography before and after percutaneous transluminal coronary angioplasty.
The velocity of blood flowing down a coronary artery may provide an index of myocardial perfusion, independent of the need for measuring the amount of myocardium supplied by a vessel. The velocity of the leading edge of contrast material was therefore measured before and after percutaneous transluminal coronary angioplasty in 15 patients utilizing digitized images from routine coronary angiography. The velocity (mean +/- SD) before percutaneous transluminal coronary angioplasty in the 15 patients was 11.9 +/- 6.0 cm/s, increasing to 21.7 +/- 8.7 cm/s after (P less than 0.01). There was a correlation between the percent change in velocity and the change in percent stenosis before and after percutaneous transluminal coronary angioplasty (r = 0.65; P less than 0.001). The mean absolute interobserver and intraobserver variabilities for the velocity measurements were 2.1 and 1.8 cm/s, respectively. Measurement of coronary flow velocity from data obtained at the time of routine coronary angiography is an easily performed reproducible technique, which may be used to assess the results of an intervention such as percutaneous transluminal coronary angioplasty.
Absorptiometry, Photon↗
Hemodynamic results of percutaneous aortic balloon valvuloplasty as assessed by sequential Doppler echocardiographic studies.
We determined the sequential hemodynamic changes after percutaneous aortic balloon valvuloplasty by means of two-dimensional and Doppler echocardiographic examinations in 25 patients immediately before, immediately after, and 24 to 36 hours after valvuloplasty. An aortic valve area was determined at all three time periods by using the continuity equation from the Doppler velocity profiles. The aortic valve area by Doppler echocardiography immediately before valvuloplasty correlated with that determined by cardiac catheterization (r = 0.85, SEE = 0.08 cm2). The mean aortic valve gradient by Doppler echocardiography was 50 +/- 22 mm Hg before the procedure, decreasing to 29 +/- 12 mm Hg (P less than 0.001), with a small, but significant, increase 1 day later to 33 +/- 13 mm Hg (P less than 0.001). The mean subvalvular velocity increased from 0.44 +/- 0.13 to 0.52 +/- 0.15 m/sec immediately after valvuloplasty (P less than 0.001), increasing further to 0.60 +/- 0.16 m/sec 1 day later (P less than 0.001). The resultant aortic valve area increased from 0.45 +/- 0.11 to 0.73 +/- 0.18 cm2 immediately after (P less than 0.05). One day later, the aortic valve area increased further to 0.86 +/- 0.19 cm2 (P less than 0.05). Because of the dynamic changes occurring during the first 24 to 36 hours after balloon valvuloplasty, hemodynamic measurements taken immediately after the procedure may underestimate the efficacy of this technique.
Aged↗
Determination of left-sided pressure gradients by utilizing Doppler aortic and mitral regurgitant signals: validation by simultaneous dual catheter and Doppler studies.
Continuous wave Doppler echocardiography is an accurate and reproducible method for determination of intracardiac pressure gradients in stenotic valve lesions and right-sided regurgitant lesions. Twenty-three patients with either mitral or aortic regurgitation underwent simultaneous continuous wave Doppler and dual catheter pressure recordings to determine if instantaneous pressure gradients can be accurately determined by Doppler ultrasound in left-sided regurgitant valve lesions. Using the modified Bernoulli equation, the maximal and mean pressure gradients between the left ventricle and left atrium were determined by continuous wave Doppler ultrasound in patients with mitral regurgitation and compared with simultaneous catheter-derived pressures. The mean and end-diastolic pressure gradients between the aorta and left ventricle were determined by continuous wave Doppler ultrasound in patients with aortic regurgitation and compared with simultaneous catheter-derived pressures. Diastolic half-times by both continuous wave Doppler ultrasound and catheter pressures were compared in patients with aortic regurgitation. There was a linear correlation between the mean gradients in all patients (r = 0.94; SEE = 6 mm Hg) with a similar correlation between the instantaneous gradients (r = 0.98; SEE = 8 mm Hg). There was a linear correlation between diastolic half-times by catheter and Doppler ultrasound (r = 0.95; SEE = 39 ms). As with other valvular lesions, continuous wave Doppler echocardiography can be used in patients with mitral or aortic regurgitation to accurately determine intracardiac pressure gradients.
Adult↗
Doppler echocardiographic observations during percutaneous aortic balloon valvuloplasty.
To evaluate the hemodynamic changes occurring with percutaneous aortic balloon valvuloplasty for aortic stenosis, Doppler echocardiography was performed during the procedure in 16 patients. During balloon inflation, peak velocity and ejection time of the aortic valve systolic signals increased (26 and 30%, respectively; p less than 0.001). Aortic regurgitation deceleration time decreased from 1,337 to 625 ms (p less than 0.001). In three patients, aortic regurgitation stopped before end-diastole; in four patients, end-diastole forward flow across the aortic valve was documented. The deceleration time of the mitral valve inflow signal decreased from 303 to 194 ms (p less than 0.001) during balloon inflation, concurrently with an increase in left ventricular diastolic pressure. Mitral regurgitation signals became more prominent during inflation in 10 patients. Changes that occur during balloon inflation in the aortic valve include progressive left ventricular outflow obstruction, equalization of diastolic aortic and left ventricular pressures and changes in diastolic compliance.
Aged↗
Mechanism of reduction of aortic valvular stenosis by percutaneous transluminal balloon valvuloplasty: report of five cases and review of literature.
Among five patients (69 to 93 years of age) in whom percutaneous transluminal balloon valvuloplasty was performed for severe aortic stenosis, fractures of cuspid calcium were observed in three, fractures and a cuspid tear in one, and no gross alterations in one. Aortic stenosis resulted from degenerative (senile) calcification of tricuspid aortic valves in two patients, calcification of congenitally bicuspid aortic valves in two, and postinflammatory (presumably rheumatic) fibrocalcific disease in one. Fractures of calcific lesions, by allowing hingelike motion along their sites, seemed to facilitate cuspid mobility and thereby provided the apparent morphologic substrate for reduction in functional stenosis. Among three cases with fused commissures (two bicuspid and one postinflammatory), however, mobility of the conjoined cusps was not achieved after valvuloplasty, despite fracture of calcific nodules in the adjacent valve pocket of one case, because the fused and calcified commissures were not split or fractured and therefore continued to act as rigid struts that impeded cuspid motion. In the current autopsy evaluation of the effects of aortic balloon valvuloplasty, greater cuspid mobility seemed to be achieved in subjects with degenerative calcific stenosis than in those with calcified bicuspid valves or distortion by postinflammatory disease.
Age Factors↗
Chronic aortic regurgitation: indications for operation--1988.
Timing of operation in a patient with severe aortic regurgitation is a difficult and controversial decision, especially when the patient is asymptomatic or minimally symptomatic. A rational decision can be made when the pathophysiologic features of aortic regurgitation and the natural history of medically treated patients are understood and the benefits and risks associated with aortic valve replacement are known. Proper interpretation of the literature involving echocardiography and nuclear cardiology is essential, as is consideration of the constantly changing surgical techniques and results. Aortic valve replacement should be recommended for those patients with chronic aortic regurgitation who are severely symptomatic (New York Heart Association Functional Class III or IV), in order to ameliorate symptoms and increase longevity. In asymptomatic or minimally symptomatic patients, close continued serial follow-up is necessary in order to detect the onset of resting left ventricular dysfunction and to recommend the optimal timing for surgical intervention.
Aortic Valve Insufficiency↗
Doppler evaluation of results of percutaneous aortic balloon valvuloplasty in calcific aortic stenosis.
To evaluate the short-term results of percutaneous aortic balloon valvuloplasty, 55 consecutive elderly patients with symptomatic, severe aortic stenosis who were at high risk for surgical intervention underwent the procedure, with follow-up by clinical evaluation and Doppler echocardiography. Over a mean follow-up of 6.2 months, there were three early deaths (less than 30 days) and eight late deaths. Nine patients underwent subsequent aortic valve surgery, and four had repeat balloon valvuloplasty. Doppler echocardiography revealed a reduction in aortic valve mean gradient from 48 +/- 18 to 33 +/- 12 mm Hg after the procedure (p less than 0.0001) but a return to 46 +/- 16 mm Hg at follow-up (p less than 0.05). The aortic valve area increased from 0.54 +/- 0.15 to 0.85 +/- 0.23 cm2 after the procedure (p less than 0.0001), but there was a significant decrease to 0.67 +/- 0.19 cm2 at follow-up (p less than 0.05). Of patients free of aortic valve operation or death after 30 days after the procedure, 76% were severely symptomatic before the procedure as compared with 38% at follow-up. In patients undergoing percutaneous aortic balloon valvuloplasty, there is a continued high short-term mortality and a significant incidence of restenosis over short-term follow-up. Nonetheless, a subset of patients do experience sustained clinical improvement from this procedure.
Aged↗
Follow-up observations in patients with mitral valve prolapse.
The discrepancies reported in various studies with respect to long-term prognosis in mitral valve prolapse can be attributed to the criteria employed for diagnosis and to the differing patient populations studied. Furthermore, mitral valve prolapse is not a single, well-defined disease but reflects rather a broad spectrum of a disease process. Echocardiographically, patients can be identified with redundant, thickened leaflets with excessive mitral valve motion and prolapse as well as those with normal appearing leaflets but systolic prolapse representative of differing disease processes with differing prognosis. The incidence of sudden cardiac death is estimated at a low value of 1.9/10,000 patients per year. In the presence of a normal resting ECG, with no hemodynamically-meaningful mitral regurgitation and no evidence of redundant mitral leaflets the risk is even less. Cerebral embolic events occur with an estimated incidence of 1/6000 patients per year, similarly low; it can be assumed that patients with very myxomatous, redundant mitral leaflets have the highest risk. The incidence of infective endocarditis is also low, estimated at 1/5725 patients per year (0.175%). Risk factors for complications include: a systolic murmur, advanced age, male sex and leaflet redundancy. The most important complication is mitral regurgitation for which the incidence is highest in older men and in the presence of left ventricular, dilatation.
Cerebrovascular Disorders↗
Endomyocardial biopsy in 30 patients with primary amyloidosis and suspected cardiac involvement.
Thirty patients with primary amyloidosis in whom cardiac involvement was suspected underwent endomyocardial biopsies. Medical records and biopsies were reviewed and echocardiograms were interpreted by observers who were unaware of the recorded findings. Cardiac amyloidosis was documented by endomyocardial biopsy in 30 (100%) of the patients. In two patients, amyloid was present in only one of four specimens, suggesting that a minimum of four biopsy samples is necessary to eliminate the possibility of sampling error. Only 36 (55%) of 65 biopsy specimens of extracardiac tissues contained amyloid. Findings were positive for amyloidosis in 11 (58%) of 19 rectal biopsies and in 16 (52%) of 31 bone marrow biopsies. Of interest, only the endomyocardial biopsy tissues were positive for amyloid in eight (27%) of the 30 patients, among whom 12 extracardiac biopsies had been performed. Two-dimensional echocardiography was consistent with the diagnosis of amyloidosis in 19 (68%) of 28 patients and was abnormal but nonspecific in the remainder. Endomyocardial biopsy frequently provides information about cardiac involvement with amyloid when biopsy of other organs is negative or echocardiography is nonspecific.
Adult↗
Doppler demonstration of the mechanism of mitral regurgitation mimicking aortic stenosis.
Seven patients with prolapsed posterior mitral leaflet were identified in whom the clinical findings were suggestive of aortic stenosis. In each instance, the murmur was best appreciated at the parasternal area. The murmur radiated to the carotids in two patients. Spatial mapping with pulsed-wave Doppler as well as continuous-wave Doppler examination demonstrated the presence of mitral regurgitation and also that the regurgitant stream was directed to the anterior left atrial wall near the base of the aorta.
Adult↗