RESUMEN

OBJECTIVE: Haitian women have a high relative incidence of clinical presentation with peripartum cardiomyopathy (PPCM): an incidence estimated at one case per three hundred live births, a ten-fold occurrence compared to American women. Our objective has been to test the hypothesis that some Haitian women may have a forme fruste of PPCM while still without clinical symptoms. METHOD: A preliminary case-control study was conducted at the Hospital Albert Schweitzer (HAS), Deschapelles, Haiti, in which 25 apparently healthy postpartum women, without cardiovascular symptoms and with a normal cardiovascular clinical examination, were selected from a consecutive list of obstetrical deliveries and screened by echocardiography for left ventricular dysfunction. RESULT: Four out of 25 patients (16%) had asymptomatic left ventricular dysfunction that subsequently evolved towards either improvement or deterioration. Supporting evidence for the existence of asymptomatic left ventricular dysfunction or forme fruste PPCM is presented. A hypothetical schema of the pathophysiology of PPCM explains how a latent phase of variable duration may exist prior to onset of detectable clinical heart failure. CONCLUSION: Screening Haitian women during the last month of pregnancy or in the early postpartum period may help to detect asymptomatic left ventricular dysfunction. Early detection and treatment of PPCM in a known high risk population could lead to improvements in maternal and fetal mortality and morbidity.

Asunto(s)

RESUMEN

BACKGROUND: The therapeutic benefit of thrombolytic therapy has been shown to correlate directly with completeness (TIMI grade 3 flow) and speed of reperfusion of the infarct-related coronary artery. The purpose of the RAPID II study was to determine whether a double-bolus regimen of reteplase, a recently developed deletion mutant of wild-type tissue plasminogen activator, could improve 90-minute coronary artery patency rates achieved with the most successful standard regimen, an "accelerated" front-loaded infusion of alteplase. METHODS AND RESULTS: Three hundred twenty-four patients with acute myocardial infarction were randomized to receive (along with intravenous heparin and aspirin) either a 10 plus 10 megaunits double bolus of reteplase or front-loaded alteplase. The primary end point of "patency at 90 minutes, graded according to the TIMI classification" was centrally assessed in a blinded fashion. Infarctrelated coronary artery patency (TIMI grade 2 or 3) and complete patency (TIMI grade 3) at 90 minutes after the start of thrombolytic therapy were significantly higher in the reteplase-treated patients (TIMI grade 2 or 3: 83.4% versus 73.3% for front-loaded alteplase-treated patients, P = .03; TIMI grade 3: 59.9% versus 45.2%, P = .01). At 60 minutes, the incidence of both, patency and complete patency, was also significantly higher in reteplase-treated patients (reteplase versus alteplase, TIMI grade 2 or 3: 81.8% versus 66.1%, P = .01; TIMI grade 3: 51.2% versus 37.4%, P < .03). Reteplase-treated patients required fewer acute additional coronary interventions (13.6% versus 26.5%, P < .01), and 35-day mortality was 4.1% for reteplase and 8.4% for alteplase (P = NS). There were no significant differences between reteplase and alteplase in bleedings requiring a transfusion (12.4% versus 9.7%) or hemorrhagic stroke (1.2% versus 1.9%). CONCLUSIONS: Reteplase, when given as a double bolus of 10 plus 10 megaunits to patients with acute myocardial infarction, achieves significantly higher rates of early reperfusion of the infarct-related coronary artery and requires significantly fewer acute coronary interventions than front-loaded alteplase without an apparent increased risk of complications.

Asunto(s)

RESUMEN

BACKGROUND: Oxygen uptake (VO2) is frequently measured or predicted in patients referred to cardiac rehabilitation programs to quantify functional capacity and prescribe exercise. When entering Phase II programs, some patients are in an anemic state that normalizes over the course of the program. The purpose of this study was to evaluate the relationship between the change in hemoglobin levels and the change in VO2 in a group of Phase II cardiac rehabilitation patients. METHODS: Sixty-six cardiac patients (45 men and 21 women) underwent a graded exercise test with the collection of expired air before and following participation in a Phase II cardiac rehabilitation program. Blood was sampled before each test for hemoglobin-hematocrit analysis. The change in absolute VO2 over the course of the rehabilitation program was chosen as the response variable in a simple regression model designed to measure the effect of normalization of hemoglobin levels during that period. RESULTS: A simple regression of the change in absolute VO2 on patient age and the changes in hemoglobin concentration and maximal work rate produced coefficient estimates that are statistically significant and have the signs one would expect. A bootstrap re-estimation of the regression model gives essentially the same coefficients and supports the results of the simple model. CONCLUSIONS: These results indicate that low levels of hemoglobin concentration adversely affect the VO2 of patients with cardiac disease and should be accounted for when assessing functional capacity. This may be even more critical when estimating rather than measuring VO2. Finally, absolute VO2 may not be the best measure of functional capacity. A submaximal marker, such as the VO2 at the ventilatory threshold, may be a more useful response variable.

Asunto(s)

Asunto(s)

RESUMEN

The accurate calculation of left ventricular (LV) wall motion from two-dimensional echocardiographs will require the accurate registration of the position from which each two-dimensional (2-D) view was obtained. This paper describes a mechanical arm with five degrees of freedom that was developed so that the position and orientation of 2-D echo sections could be calculated in three-dimensional space. High precision potentiometers, direct or gear driven, permit calibration and measurement of each of the five movements. Using the length of the arm and the angles measured by these potentiometers, the position of a 2-D section can be calculated with respect to a fixed reference point outside the body. The measurement arm was extensively retested after six months of clinical use. In patient studies, 95% confidence interval for positioning a cross-section of the long axis is +/- 6 mm. This error is similar to the cross-plane resolution to most contemporary two-dimensional transducers. On the basis of an extensive analysis of variance, recommendations are made to improve the accuracy of the arm.

Asunto(s)

Asunto(s)

RESUMEN

Bidirectional instantaneous aortic root blood flow was measured in 18 patients with aortic insufficiency (AI) using a catheter-tip velocity transducer. The magnitude of AI was quantitated by determining total forward systolic flow from the area of the flow velocity curve above the zero baseline and regurgitant diastolic flow from the curve area below the baseline. Effective forward flow (stroke volume) was calculated as the difference between total forward systolic flow and regurgitant diastolic flow. Regurgitant fraction was determined as the ratio of regurgitant flow to total forward flow. These data were compared with conventional angiographic estimates (1+ to 4+) of the degree of insufficiency. Velocity transducer determination of regurgitant fraction was 26% in the patient with 1+ AI, 37% (31-48%) in 2+ AI, 49% (35-61%) in 3+ AI and 72% in 4+ AI (regurgitant fraction vs angiographic grade, r = 0.84). Regurgitant flow per diastole was 9 ml in the patient with 1+ AI, 39 ml (20-49 ml) in 2+ AI, 57 ml (31-102 ml) in 3+ AI and 183 ml (143 and 223 ml) in 4+ AI (regurgitant diastolic flow vs angiographic grade, r = 0.73). Good correlation (r = 0.90) was found between values of regurgitant flow obtained from the left ventriculogram and those obtained using the velocity transducer. Although the overall association was good, wide, variability in regurgitant fraction and regurgitant flow was found in the 15 patients with 2+ to 3+ AI. These results suggest that the electromagnetic velocity catheter offers a simple technique for quantitating AI.

Asunto(s)

RESUMEN

Left ventricular (LV) wall motion (anterior and posterior) and simultaneous LV pressure were recorded during 30-second left anterior descending (LAD) or circumflex (CX) coronary artery occlusions in open-chest dogs to provide an echocardiographic model of the evolution of wall motion changes during myocardial ischemia. Prominent diastolic echocardiographic motion changes of progressive decrease in LV wall rapid-filling velocities (RFS), slow-filling velocities (SFS), and increased end-diastolic diameter were accompanied by a marked increase in initial and end-diastolic pressures (150% and 70%, respectively; all p less than 0.05). Early (within ten seconds) and progressive decrease in rat (SES), amplitude (E), and duration (TTR) of systolic motion were noted with an increased systolic diameter (p less than 0.05). Ischemic regions developed a characteristic pattern with early relaxation followed by a diastolic inward motion (DIM). These observations confirm and extend other investigators' findings on the motion of the ischemic myocardium and may be applicable to responses to transient myocardial ischemia noted in humans.

Asunto(s)

Asunto(s)

RESUMEN

Simultaneous left ventricular echograms and high-gain pressure recordings were made during 30 s of regional myocardial ischemia induced by snare occlusions of the proximal left anterior descending (LAD) or left circumflex (LCx) coronary arteries in open-chest dogs. Left ventricular diastolic diameter (d) and pressure (p) were measured during slow filling. A normalized (for diameter D) distensibility estimate (DE = delta d/delta p/D) was calculated, as were slow filling slopes (SFSs) of the septum and posterior wall. After occlusion, significant (p less than 0.05) decreases of DE and anterior and posterior left-ventricular-wall mid-diastolic normalized slow-filling slopes (ASFS/D and PSFS/D) were observed. Correlations were noted between percentage decreases of DE and ASFS/D (r = 0.69, p less than 0.0001) and PSFS/D (r = 0.62, p less than 0.0001). No significant differences between decreases of DE and SFS were noted between ischemic and non-ischemic regions. Transient regional myocardial ischemia was associated with a generalized alteration in left ventricular filling patterns in mid-diastole.

Asunto(s)

RESUMEN

A catheter-tip velocity transducer with two high-fidelity pressure manometers was used to evaluate the left ventricular (LV) hemodynamic effects of intravenous propranolol (10 mg). Nine patients without clinical evidence of heart failure were studied. Pulsatile ascending aortic blood flow velocity and pressure and LV pressure were measured continuously during drug administration. Beat-to-beat changes in stroke volume index, stroke work index, LV end-diastolic pressure, maximum blood flow velocity and acceleration, and maximum LV dP/dt were determined. Propranolol produced a decrease in maximum blood flow velocity (from 58 +/- 4.7 to 42 +/- 5.1 cm/sec, p less than 0.002), and acceleration (from 1181 +/- 130 to 847 +/- 117 cm/sec2, p less than 0.002, max dP/dt (from 1361 +/- 70 to 1146 +/- 63 mm Hg/sec, p less than 0.002), stroke volume index (from 47 +/- 3.0 to 38 +/- 3.2 ml/m2, p less than 0.002) and total stroke work index (from 702 +/- 33 to 603 +/- 44 mJ/m2 p less than 0.04), with little change in mean aortic pressure, peak systolic pressure and LV end-diastolic pressure. Depression in myocardial function was detectable within 1 minute after initiation of propranolol and persisted when negative chronotropic effects were eliminated by atrial pacing. The multisensor catheter technique allows rapid and safe detection of changes in cardiovascular function during propranolol administration in conscious man.

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)

RESUMEN

Although the motion of the left ventricular wall has been examined by angiographic and by echocardiographic studies in both experimental animals and in man, there are no complete studies of the motion of the left ventricular posterior wall throughout the entire cardiac cycle. Because the posterior wall can be demonstrated echocardiographically in essentially all patients, it offers a potential of wide clinical application in the evaluation of left ventricular function. This study was undertaken to provide a detailed inclusive analysis of the motion of the left ventricular posterior wall. In 64 human volunteers the echocardiographic movements of the left ventricular posterior wall were identified. Using the R wave of the electrocardiogram as a reference and to identify phases of the cardiac cycle, each movement of the left ventricular posterior wall was temporally related to aortic or mitral valvular movements (or both). In a subset of 14 subjects, dual M-mode echocardiograms confirmed the validity of these temporal relationships. In three subjects, high-fidelity recordings from catheter tip micromanometers were made simultaneously with the echocardiogram to permit description of the temporal relationships between pressure and motion. Results of this study provide a base of normal data for comparison with the motion of the left ventricular posterior wall in a variety of diseases and in response to therapy.

Asunto(s)

RESUMEN

Because no accurate and readily applied method exists for continuous recording of left ventricular cavity dimensions and wall motion in man, we designed a catheter-mounted echocardiographic probe. The purpose of this report is to describe the instrumentation, technique, limitations, complications and preliminary observations employing the probe in humans. The echo transducer built into a cardiac allowed positioning in the right heart under fluoroscopy. The echo signals permitted continuous left ventricular cavity measurements at rest and during maneuvers. Our results suggest that intracardiac echo may be able to provide clear definition of motion patterns of the mitral valve and left ventricular walls. The ultrasonic catheter is an instrument that potentially offers a new technique for continuous monitoring of left ventricular size and motion.

Asunto(s)

RESUMEN

In summary, it is hazardous to rely solely on coronary angiography to define critical coronary stenosis. Clinically, the physiologic significance of a narrowing observed at coronary angiography can best be evaluated by obtaining additional evidence of myocardial ischemia, i.e. stress testing with ECG monitoring, resting and exercise isotope perfusion studies or ventriculographic studies. However, when evaluating coronary angiograms for critical coronary stenosis, several points are worth considering. First, a long narrowing will decrease coronary blood flow more than a short narrowing of the same severity. Second, sequential narrowings will decrease coronary blood flow more than a single narrowing of the same total length. Third, a long narrowing can be estimated more accurately than a short narrowing. Fourth, caliper measurements of coronary artery narrowings are more accurate than subjective estimation, and fifth, coronary artery dilators may increase the percentage narrowing in some cases. The complex effects of percent stenosis and length of stenosis on the physiology of coronary blood flow must always be considered when evaluating angiograms. In addition, the angiographic or photographic artifacts produced by short narrowings tend to overestimate the percent stenosis and, thus, calipers should be used to measure percent stenosis, especially in the short narrowings.

Asunto(s)

Asunto(s)

Asunto(s)

RESUMEN

Percutaneous left ventricular catheterisation with a 4F (O.D. 1.33 mm) catheter-tip pressure transducer is described. The transducer is small enough so that it can be introduced through a short 4F arterial insertion sheath or a Brockenbrough Trans-septal catheter. Experience in 35 patients suggests that this ultraminiature catheter mounted pressure transducer is a valuable addition to the cardiac catheterisation laboratory.

Asunto(s)