Biomedical subjects

R G McKay

Publications and source records attributed to R G McKay.

At least 73 records · Page 4Linked to original sources

PubMed1988

Assessment of aortic pressure-volume relationships with an impedance catheter.

Volume measurements obtained with an impedance catheter (impedance volume measurements) have been used previously in determining pressure-volume relationships in the right and left ventricles and in the right atrium. The purpose of the present study was to determine the utility of impedance volume techniques in the assessment of aortic pressure-volume relationships in animals and humans. Experiments to develop this methodology were first performed in ten anesthetized dogs, with simultaneous measurements of aortic pressure (micromanometer), diameter (ultrasonic crystals), and impedance volume. Transient (20 sec) inferior vena cava (IVC) occlusion and nitroprusside infusion resulted in a reproducible series of aortic pressure-volume and pressure-diameter points. In each case changes in impedance volume closely paralleled changes in diameter. From the wide range of pressure-volume points, it was possible to construct pressure-volume plots for a single cardiac cycle, as well as longer loops over a 20-40 mm Hg pressure range. End-systolic and end-diastolic pressure-volume points could subsequently be identified, which outlined a more precise pressure-volume relationship that was linear in six cases and curvilinear in four cases, depending on the level of aortic pressure. We extended these techniques to human subjects undergoing diagnostic cardiac catheterization. Studies using the impedance catheter in the aorta were performed in 11 patients. Aortic pressure-volume curves were elicited during Valsalva maneuver to obtain data over a range wider than that of a single cardiac cycle. Measurements of relative volume were calibrated with simultaneous M-mode echocardiography in three patients. We conclude that pressure-volume relationships in the aorta can be assessed with impedance volume techniques, making possible in vivo measurements of arterial compliance. Potential nonlinearities in aortic P-V relationships require that the assessment of aortic compliance encompass as much as possible of the physiologic range of pressure and volume.

Animals↗

PubMed1988

Percutaneous balloon mitral valvuloplasty in a pregnant woman with mitral stenosis.

A 39-year-old woman with symptomatic mitral stenosis underwent percutaneous mitral valvuloplasty at the end of her first trimester of pregnancy. Balloon dilatation utilizing a double 18-20 mm balloon technique resulted in improvement in mean mitral gradient (16 to 7 mmHg) and in calculated mitral valve area (1.4 to 2.4 cm2), without significant complications and with an estimated radiation exposure to the fetus of less than 0.2 rads. The procedure resulted in disappearance of symptoms of congestive heart failure and allowed for discontinuation of diuretics. The subsequent course of gestation was uncomplicated and a normal baby boy was delivered in the 36th wk. We conclude that percutaneous mitral valvuloplasty may produce successful palliation of symptoms in patients with mitral stenosis during pregnancy.

Adult↗

PubMed1988

Hemodynamic responses to noninvasive external cardiac pacing.

Although improvements in noninvasive external cardiac pacing have led to a technique with reliable electrical capture and reduced patient discomfort, hemodynamic responses to this pacing mode have not been described previously. Accordingly, this technique was applied to 16 patients with a clinical diagnosis of angina pectoris undergoing cardiac catheterization. Three patients had normal coronary arteries, whereas the remaining 13 had significant coronary artery disease. All patients had noninvasive pacing at increasing heart rates to 85 percent of age-predicted maximal heart rate. At maximal pacing, all patients demonstrated a rise in atrial, pulmonary artery, and mean aortic pressures. Cardiac index remained unchanged, reflecting parallel increases in arteriovenous oxygen difference and oxygen consumption. One minute after cessation of pacing, pulmonary artery pressure and oxygen consumption remained elevated, whereas arteriovenous oxygen difference returned to baseline with a subsequent rise in cardiac index. Angina occurred in eight patients with coronary artery disease at peak pacing and was accompanied by a rise in left ventricular end-diastolic pressure after pacing. In eight patients without pacing-induced angina, including the three patients with normal coronary arteries, there was no significant change in left ventricular end-diastolic pressure after pacing. It is concluded that noninvasive external cardiac pacing produces a rise in both right and left heart filling pressures and in oxygen consumption that persist after pacing, and may provoke angina and hemodynamic abnormalities consistent with myocardial ischemia. This mode of pacing appears hemodynamically safe with maintenance of cardiac index and aortic pressure at 85 percent of maximal age-predicted heart rate.

Angina Pectoris↗

PubMed1988

Prediction of severity of aortic stenosis: accuracy of multiple noninvasive parameters.

PURPOSE: As newer non-medical techniques are developed to treat older patients with severe aortic stenosis, reliable noninvasive diagnosis of the condition will become increasingly important. For this reason, the accuracy of multiple noninvasive indexes for quantitation of the severity of aortic stenosis was evaluated, relative to catheterization-determined aortic valve area. PATIENTS AND METHODS: To evaluate the accuracy of multiple noninvasive parameters in assessing the presence and extent of aortic valve narrowing, noninvasive and catheterization correlations of the severity of aortic stenosis were obtained on 121 occasions in 81 patients (mean age, 76 +/- 11 years). Forty patients had studies performed before and after valvuloplasty. Noninvasive studies included the time to one-half carotid upstroke and carotid ejection time, corrected for heart rate, measured from a carotid pulse tracing; M-mode echocardiographic aortic valve excursion; mean pressure gradient across the aortic valve assessed by Doppler technique; the ratio of the peak to mean pressure gradient by Doppler; and Doppler aortic valve area assessed using the following continuity equation: aortic valve area = A X V/V1, where A = left ventricular outflow tract area, V = peak left ventricular outflow tract velocity, and V1 = peak velocity in the aortic stenotic jet. Mean aortic valve gradients and area (calculated using the Gorlin formula) were also assessed at cardiac catheterization. RESULTS: The correlations between the catheterization measurement of aortic valve area and the various noninvasive measurements were as follows: time to one-half carotid upstroke (r = -0.32, p less than 0.001); corrected left ventricular ejection time (r = -0.24, p less than 0.05); aortic valve excursion (r = 0.51, p less than 0.001); mean gradient by Doppler study (r = -0.44, p less than 0.001); mean gradient by catheterization analysis (r = -0.55, p less than 0.001); peak to mean gradient ratio measured by continuous wave Doppler (r = 0.38, p less than 0.001); and aortic valve area assessed using the Doppler continuity equation (r = 0.85, p less than 0.001). CONCLUSION: Noninvasive determination of aortic valve area using the continuity equation is an accurate means of assessing the severity of aortic stenosis. Although multiple other noninvasive parameters also correlate with aortic valve area measured at catheterization, there is too much scatter of data points to permit accurate prediction of catheterization aortic valve area in any given patient.

Aged↗

PubMed1988

Time course of left ventricular dilation after myocardial infarction: influence of infarct-related artery and success of coronary thrombolysis.

Dilation of the left ventricle after myocardial infarction is common, occurs rapidly (within 2 weeks of infarction) and may be self-limited. To evaluate the time course of postinfarction left ventricular dilation and to assess the impact of successful coronary thrombolysis, serial radionuclide left ventricular volume analyses were performed in 36 patients undergoing attempted thrombolysis for acute transmural myocardial infarction. All patients underwent cardiac catheterization, coronary angiography and attempted thrombolysis within 7 h of the onset of symptoms. The site of coronary occlusion was the left anterior descending coronary artery in 17 patients, the right coronary artery in 18 and, in 1 patient, occluded bypass grafts to the right and left circumflex coronary arteries. Attempted reperfusion using a thrombolytic agent was successful in 22 individuals, occurring 5 +/- 1 h after the onset of symptoms. Gated radionuclide ventriculography was performed early (mean time 1 day after admission, n = 36), subacutely (mean time 11 days postinfarction, n = 36) and late after infarction (mean time 10.5 months, n = 25), and a geometric technique was used to measure serial left ventricular end-diastolic volume. Left ventricular end-diastolic volume for the entire group increased significantly (p less than 0.01) from 153 +/- 30 ml at baseline to 172 +/- 45 ml (at 11 days) to 220 +/- 63 ml (at 10.5 months). Twenty of 36 patients showed greater than 20% increase in left ventricular end-diastolic volume (dilation) with time. This appeared early in seven patients, occurred remote from infarction in seven others and showed a progressive pattern in six.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1988

Combined aortic and mitral balloon valvuloplasty in patients with critical aortic and mitral valve stenosis: results in six cases.

Six patients with severe combined aortic and mitral valve stenosis underwent double valve balloon dilation as an alternative to surgical valve replacement. Cardiac catheterization in all patients before valve dilation revealed heavily calcified aortic and mitral valves with severe stenosis and minimal regurgitation. Balloon aortic valvuloplasty was performed in each patient with a 20 mm balloon dilation catheter passed retrograde through the aortic valve whereas mitral valvuloplasty was performed transseptally with either a single or double balloon technique. After dilation, the mean aortic and mitral gradients decreased in all patients, with the area of the aortic and the mitral valve increasing from 0.5 +/- 0.3 to 0.9 +/- 0.3 cm2 and from 0.7 +/- 0.1 to 1.5 +/- 0.7 cm2, respectively. The procedures were well tolerated, with no embolic events and no significant increase in valvular regurgitation, and resulted in a reduction in symptoms of dyspnea on exertion and weakness in all patients that has persisted for an average of 5.7 months of follow-up in five of the six patients. It is concluded that combined dilation of stenotic aortic and mitral valves can be accomplished percutaneously and may be considered for patients with combined valvular stenosis who refuse or are deferred from surgical intervention.

Aged↗

PubMed1988

Current complications of diagnostic and therapeutic cardiac catheterization.

Data from 2,883 cardiac catheterizations performed during an 18 month period (from July 1986 through December 1987) were analyzed to assess the current complication profile of diagnostic and therapeutic procedures. Procedures performed during the study period included 1,609 diagnostic catheterizations, 933 percutaneous transluminal coronary angioplasties and 199 percutaneous balloon valvuloplasties. Overall, the mortality rate was 0.28% but ranged from 0.12% for diagnostic catheterizations to 0.3% for coronary angioplasty and 1.5% for balloon valvuloplasty. Emergency cardiac surgery was required in 12 angioplasty patients (1.2%). Cardiac perforation occurred in seven patients (0.2%), of whom six were undergoing valvuloplasty, and five (2.5% of valvuloplasty attempts) required emergency surgery for correction. Local vascular complications requiring operative repair occurred in 1.9% of patients overall, ranging from 1.6% for diagnostic catheterization to 1.5% for angioplasty and 7.5% for valvuloplasty. Although the complication rates for diagnostic catheterization compare favorably with those of previous multicenter registries, current overall complication rates are significantly higher because of the performance of therapeutic procedures with greater intrinsic risk and the inclusion of increasingly aged and acutely ill or unstable patients.

Aged↗

PubMed1988

Diastolic function in patients with aortic stenosis: influence of left ventricular load reduction.

Pressure overload hypertrophy of the left ventricle due to aortic stenosis is associated with abnormalities of left ventricular isovolumic relaxation and early diastolic filling. The relative contribution of the hemodynamic load on the left ventricle to the impairment of diastolic function observed in this disorder remains poorly understood. To study this relation, the vasodilator nitroprusside was administered to eight patients with aortic stenosis and normal systolic function. The effect of a short-term reduction in left ventricular preload and afterload on left ventricular isovolumic relaxation and early diastolic filling was assessed by analysis of simultaneous micromanometer left ventricular pressure and radionuclide angiographic volume measurements. At baseline, left ventricular systolic and end-diastolic pressures were markedly elevated, and associated with prolongation of the time constant of left ventricular relaxation and depression of the left ventricular peak filling rate. Infusion of nitroprusside resulted in reduction of left ventricular systolic (204 +/- 31 to 176 +/- 31 mm Hg, p less than 0.05) and end-diastolic (31 +/- 8 to 18 +/- 6 mm Hg, p less than 0.05) pressures, with no associated improvement in time constant of left ventricular pressure decay (T) (68 +/- 25 to 80 +/- 37 ms, p = NS), T 1/2 (34 +/- 8 to 34 +/- 14 ms, p = NS), left ventricular peak filling rate (2.3 +/- 0.5 to 2.3 +/- 0.8 end-diastolic volume/s, p = NS) or time to left ventricular peak filling rate (150 +/- 50 to 144 +/- 37 ms, p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1988

Transcatheter closure of ventricular septal defects.

Between January and October, 1987, we attempted percutaneous transcatheter closure of seven ventricular septal defects (VSD) in six patients; none of the patients was a candidate for operative management. Patients' ages ranged from 8 months to 82 years (6.0-70 kg); diagnoses included postinfarction VSD (n = 4), congenital VSD (n = 1), and postoperative congenital VSD (n = 2). Indications for VSD closure were shock or respiratory failure (n = 5) or multiple episodes of endocarditis (n = 1). Closure was attempted with a Rashkind double umbrella: VSDs were crossed via the left ventricle and a guide wire was advanced to the right heart, snared with a venous catheter, and used to direct a long sheath (and ultimately the double umbrella) across the VSD. We crossed the VSD in all seven attempts, and a 17-mm double umbrella was successfully placed in each VSD. In the first (postinfarction) patient with the largest (12 mm) VSD, the umbrella embolized after 20 seconds to the pulmonary artery (without reducing flow). The other six umbrellas remained in position, either diminishing or abolishing the left-to-right shunts. Postinfarction patients had increasing VSD shunting over the next several days and died; at postmortem, the umbrellas remained well positioned in the septum, with other VSDs present. All three congenital VSDs had absent or diminished shunts after umbrella closure. These preliminary data indicate that transcatheter VSD closure is feasible in selected cases.

Angiography↗

PubMed1988

Improvement in symptoms and left ventricular performance after balloon aortic valvuloplasty in patients with aortic stenosis and depressed left ventricular ejection fraction.

The application of balloon aortic valvuloplasty to elderly patients with severe aortic stenosis and a low ventricular ejection fraction is undefined. Balloon aortic valvuloplasty was performed in a subset of 28 patients with low left ventricular ejection fraction (37 +/- 11%), severe aortic stenosis, and a mean age of 79 +/- 5 years. After valvuloplasty, significant increases were seen in aortic valve area (from 0.5 +/- 0.1 to 0.9 +/- 0.2 cm2), aortic systolic pressure (from 120 +/- 12 to 135 +/- 22 mm Hg), and cardiac output (from 4.2 +/- 1.1 to 4.8 +/- 1.6 l/min) (p less than 0.01), and significant decreases were seen in transaortic pressure gradient (from 69 +/- 25 to 35 +/- 15 mm Hg) and pulmonary capillary wedge pressure (from 24 +/- 9 to 20 +/- 7 mm Hg) (p less than 0.01). All patients had symptomatically improved at the time of discharge. Serial radionuclide ventriculography showed an increase in left ventricular ejection fraction from 37 +/- 11% before valvuloplasty to 44 +/- 14% within 48 hours after dilatation and to 49 +/- 13% at 3 months after dilatation. However, there was substantial heterogeneity of response. Thirteen patients (group A) showed progressive increases in left ventricular ejection fraction (from 34 +/- 11% to 49 +/- 15% to 58 +/- 11%, p less than 0.0001), whereas 15 patients (group B) showed no significant change in ejection fraction (from 41 +/- 10% to 40 +/- 13% to 41 +/- 10%, p = NS) over 3 months. There was no difference between these groups with respect to age, extent of coronary artery disease, history of myocardial infarction, and aortic valve area before and after valvuloplasty. However, peak systolic wall stress and left ventricular dimensions were higher in group B compared with group A. In conclusion, balloon aortic valvuloplasty may result in symptomatic improvement in patients with aortic stenosis and depressed left ventricular ejection fraction; some patients develop progressive increases in ejection fraction, whereas others fail to show improvement.

Aged↗

PubMed1988

Depression of systolic and diastolic myocardial reserve during atrial pacing tachycardia in patients with dilated cardiomyopathy.

Previous reports have shown that increases in heart rate may result in enhanced left ventricular (LV) systolic and diastolic performance. To assess whether this phenomenon occurs in the presence of depressed LV function, the effects of pacing on LV pressure and volume were compared in seven patients with dilated cardiomyopathy (LV ejection fraction 0.19 +/- 0.11) and six patients with no or minimal coronary artery disease (LV ejection fraction 0.69 +/- 0.11). Patients with normal LV function demonstrated significant increases in LV peak-positive dP/dt, LV end-systolic pressure-volume ratio, LV peak filling rate, and a progressive leftward and downward shift of their pressure-volume diagrams, compatible with increased contractility and distensibility in response to pacing tachycardia. There was no change in LV peak-negative dP/dt or tau. Patients with dilated cardiomyopathy, in contrast, demonstrated no increase in either LV peak-positive dP/dt or the end-systolic pressure-volume ratio, and absence of a progressive leftward shift of their pressure-volume diagrams. Moreover, cardiomyopathy patients demonstrated no increase in LV peak-negative dP/dt or LV peak filling rate and a blunted downward shift of the diastolic limb of their pressure-volume diagrams. Tau, as determined from a derivative method, became abbreviated although never reaching control values. We conclude that patients with dilated cardiomyopathy may demonstrate little or no significant enhancement in systolic and diastolic function during atrial pacing tachycardia, suggesting a depression of both inotropic and lusitropic reserve.

Cardiac Output↗

PubMed1988

Noninvasive external cardiac pacing for thallium-201 scintigraphy.

Improvements in noninvasive external cardiac pacing have led to a technique with reliable electrical capture and tolerable patient discomfort. To assess the use of this modality of pacing in combination with thallium scintigraphy as a noninvasive pacing stress test, we applied simultaneous noninvasive cardiac pacing, hemodynamic monitoring, and thallium-201 scintigraphy in 14 patients undergoing cardiac catheterization for chest pain syndromes. Two patients had normal coronary arteries, while the remaining 12 had significant coronary artery disease. Thallium scintigraphic responses to pacing were compared to routine exercise thallium stress testing in nine of these 14 patients. All patients were noninvasively paced to more than 85% of the age-predicted maximum heart rate. Twelve patients demonstrated reversible thallium defects, which corresponded in 11 cases to significant lesions seen on coronary angiography. Of nine patients who underwent both pacing and exercise thallium stress tests, comparable maximal rate-pressure products were achieved. Moreover, thallium imaging at peak pacing and during delayed views did not differ significantly from exercise thallium scintigraphy. A limiting factor associated with the technique was local patient discomfort, which occurred to some degree in all patients. We conclude that noninvasive external cardiac pacing together with thallium scintigraphy is capable of detecting significant coronary artery disease and may be comparable to routine exercise thallium stress testing. This new modality of stress testing could be useful in patients unable to undergo the exercise required for standard exercise tolerance testing, particularly if improvements in the technology can be found to reduce further the local discomfort.

Cardiac Catheterization↗

PubMed1987

Usefulness of percutaneous transluminal coronary angioplasty for unstable angina pectoris after non-Q-wave acute myocardial infarction.

Without revascularization, patients with non-Q-wave acute myocardial infarction (AMI) are predisposed to angina, recurrent AMI and cardiac death. Percutaneous transluminal coronary angioplasty (PTCA) was performed in 68 patients with angina an average of 2.3 months after non-Q-wave AMI (41 anterior, 27 inferior). Mean diameter stenosis was 95%, with collateralized total occlusion of the infarct-related artery in 23 patients. PTCA was successful in 87% (59 of 68), with a mean residual stenosis of 30%. One patient had emergency bypass surgery. Long-term follow-up (average 17 +/- 10 months) was available for 58 of the 59 patients in whom PTCA was successful. Recurrent angina developed in 41% (24 of 58), but was relieved by repeat PTCA in 14, by late coronary artery bypass surgery in 4 and by medical therapy in 6. There was 1 nonfatal AMI, due to progressive disease in a nondilated vessel, and 1 noncardiac death At last follow-up, 46 of 58 patients (79%) were asymptomatic and fully active or employed. Thus, patients undergoing PTCA for angina after non-Q-wave AMI appear to have a relatively high clinical restenosis rate, but with repeat PTCA have a low incidence of subsequent angina, AMI and cardiac death.

Adult↗

PubMed1987

Effects of positional changes on inferior vena caval size and dynamics and correlations with right-sided cardiac pressure.

Effects of supine and lateral positions on the size and shape of the inferior vena cava (IVC) were studied in 30 normal persons and in 53 patients with cardiac disease undergoing right-sided cardiac catheterization. In normal subjects, mean values for both IVC diameter and area decreased significantly (p less than 0.01) from the right lateral (22 +/- 3 mm and 3.9 +/- 0.6 cm2, respectively) to the supine position (15 +/- 5 mm; 1.8 +/- 0.9 cm2) to the left lateral position (7 +/- 3 mm; 0.8 +/- 0.4 cm2). IVC shape was round in the right lateral, oval in the supine, and slit-like in left lateral position. In the 53 patients, significant differences in IVC diameter and area were also detected in all 3 positions. However, when separated into 2 groups according to right atrial pressure, patients with normal pressure (8 mm Hg or less) had diameter and area values equivalent to those of normal subjects, whereas patients with elevated right atrial pressure (more than 8 mm Hg) had supine and left lateral IVC diameters and areas that were larger than normal, and approximately equivalent: diameters--23 +/- 3 mm (right), 18 +/- 5 mm (supine) and 17 +/- 7 mm (left); areas--4.1 +/- 0.8 cm2 (right), 3.3 +/- 1.2 cm2 (supine) and 3.1 +/- 1.3 cm2 (left). IVC diameters and areas in all 3 positions correlated with mean right atrial pressure, measured subsequently in the supine position, but the left lateral position provided the strongest correlations (r = 0.85, IVC diameter vs right atrial pressure; r = 0.89, IVC area vs right atrial pressure).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1987

Assessment of the relationship between distal occluded pressure and angiographically evident collateral flow during coronary angioplasty.

The relationship between the presence of collateral filling on the baseline coronary angiogram and the distal occluded pressure obtained during balloon inflation was examined in 83 patients undergoing coronary angioplasty. The patients were divided into three groups: Group I (n = 40) had conventional stenoses (80% to 95% luminal diameter narrowing) without angiographically evident collaterals, group II (n = 22) had conventional stenoses with angiographically present collaterals, and group III (n = 21) had total or functional total occlusions (99% to 100% diameter narrowing) with angiographically evident collateral flow. There was no significant difference in age, sex, vessel distribution, clinical class, residual gradient, or residual percent stenosis following successful angioplasty among the three groups. The distal occluded pressure in group I (18 +/- 5 mm Hg) was, however, significantly lower than the distal occluded pressure in either group II (34 +/- 7 mm Hg) or group III (36 +/- 9 mm Hg) (p less than 0.001). This could not be explained by differences in aortic pressure, since there was no correlation between the mean aortic blood pressure and the distal occluded pressure and since the distal occluded pressure/aortic pressure ratio in group I (0.23 +/- 0.07) was significantly lower than that of group II (0.41 +/- 0.09) or group III (0.41 +/- 0.11) (p less than 0.001). These findings indicate a close correlation between the presence of angiographically evident collateral flow and the distal coronary artery pressure during an angioplasty balloon inflation.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗

PubMed1987

Postmortem and intraoperative balloon valvuloplasty of calcific aortic stenosis in elderly patients: mechanisms of successful dilation.

Percutaneous balloon dilation of the aortic valve has recently been proposed as a palliative procedure for treating nonsurgical candidates with calcific aortic stenosis. To assess the safety, efficacy and mechanisms of successful balloon valvuloplasty, postmortem (n = 33) and intraoperative (n = 6) balloon aortic valvuloplasty was performed in the hearts of 39 elderly patients with calcific aortic stenosis. The cause of aortic stenosis was degenerative nodular calcification in 28 cases, calcific bicuspid aortic stenosis in 8 cases and rheumatic heart disease in 3 cases. Balloon dilation was performed with 15 to 25 mm balloons in the postmortem specimens, and with 18 to 20 mm balloons in the operating room immediately before aortic valve replacement. After balloon dilation, valve orifice dimensions and leaflet mobility increased in all patients. The mechanisms of successful dilation included fracture of calcified nodules in 16 aortic valves, separation of fused commissures in 5 valves, both in 6 valves and grossly inapparent microfractures in 12 valves. Valve leaflet avulsion occurred in one heart after inflation with a clearly oversized balloon. Liberation of calcific debris, valve ring disruption or midleaflet tears did not occur in any heart. In conclusion, there are at least three mechanisms of successful aortic valvuloplasty, depending on the origin of valvular stenosis. Embolic phenomena and acute valvular regurgitation do not appear to be likely events associated with this procedure.

Aged↗

PubMed1987

Echocardiographic assessment of aortic valve area in elderly patients with aortic stenosis and of changes in valve area after percutaneous balloon valvuloplasty.

Echocardiographic studies, adequate for analysis of aortic valve area using the continuity equation, were obtained in 31 patients aged greater than or equal to 60 years who were undergoing catheterization for assessment of suspected aortic stenosis. Catheterization-determined aortic valve area was 0.74 +/- 0.30 cm2 (mean +/- SD) and Doppler-determined aortic valve areas were 0.68 +/- 0.27 and 0.65 +/- 0.27 cm2, depending on whether peak or mean velocities, respectively, were entered into the continuity equation. There were significant correlations between both of the Doppler-derived and the catheterization-determined aortic valve areas (r = 0.86, p less than 0.001 for both the continuity equation employing peak velocities and the continuity equation employing mean velocities) which were demonstrated to be linear by F test (catheterization area = -0.03 + 1.13 X Doppler area determined using peak velocities, SEE = 0.163 cm2, p less than 0.001; and catheterization area = -0.02 + 1.16 X Doppler area determined using mean velocities, SEE = 0.165 cm2, p less than 0.001). Both sets of correlations had linear regression parameters meeting the conditions for identity. Significant linear correlations were also noted between the non-invasive measurements of aortic valve excursion, ventricular ejection time, time to one-half carotid upstroke, maximal Doppler velocity and maximal Doppler gradient and catheterization aortic valve area, but the correlations were less tight than those between valve areas determined by catheterization and by Doppler continuity equation. Ten of the patients underwent percutaneous balloon aortic valvuloplasty. There were significant linear correlations between aortic valve areas determined by Doppler and catheterization methods both before valvuloplasty (r = 0.77, p = 0.01; p less than 0.001 by F test, SEE = 0.134 cm2) and after valvuloplasty (r = 0.85, p less than 0.01; p = 0.0001 by F test, SEE = 0.161 cm2). Linear regression parameters met the conditions for identity. There was also a significant linear correlation between catheterization and Doppler measurements of absolute change in aortic valve area (r = 0.79, p less than 0.01; p less than 0.001 by F test, SEE = 0.11 cm2). Aortic valve area can be determined reliably by continuity equation in elderly patients. In addition, results of balloon valvuloplasty, measured by changes in catheterization-determined aortic valve area, are accurately reflected by changes in aortic valve area determined using the continuity equation.

Aged↗

PubMed1987

Balloon dilation of mitral stenosis in adult patients: postmortem and percutaneous mitral valvuloplasty studies.

Preliminary reports have documented the utility of percutaneous balloon valvuloplasty of the mitral valve in adult patients with mitral stenosis, but the mechanism of successful valve dilation and the effect of mitral valvuloplasty on cardiac performance have not been studied in detail. Accordingly, mitral valvuloplasty was performed in five postmortem specimens and in 18 adult patients with rheumatic mitral stenosis, using either one (25 mm) or two (18 and 20 mm) dilation balloons. Postmortem balloon dilation resulted in increased valve orifice area in all five postmortem specimens, secondary to separation of fused commissures and fracture of nodular calcium within the mitral leaflets. In no case did balloon dilation result in tearing of valve leaflets, disruption of the mitral ring or liberation of potentially embolic debris. Percutaneous mitral valvuloplasty in 18 patients with severe mitral stenosis (including 9 with a heavily calcified valve) resulted in an increase in cardiac output (4.3 +/- 1.1 to 5.1 +/- 1.5 liters/min, p less than 0.01) and mitral valve area (0.9 +/- 0.2 to 1.6 +/- 0.4 cm2, p less than 0.0001), and a decrease in mean mitral pressure gradient (15 +/- 5 to 9 +/- 4 mm Hg, p less than 0.0001), pulmonary capillary wedge pressure (23 +/- 7 to 18 +/- 7 mm Hg, p less than 0.0001) and mean pulmonary artery pressure (36 +/- 12 to 33 +/- 12 mm Hg, p less than 0.01). Left ventriculography before and after valvuloplasty in 14 of the 18 patients showed a mild (less than or equal to 1+) increase in mitral regurgitation in five patients and no change in the remainder.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗