The value of injections of dye into the left heart in the study of mitral and aortic valvular disease by catheterization of the left heart

Mitral regurgitant flow and left ventricular function in patients with mitral valve disease

A direct indicator-dilution principle for measurement of regurgitant flow has been applied in the study of 39 patients with mitral valve disease.

Certain technical modifications in the procedure appear to have abolished the grossly anomalous results encountered previously, enabling a degree of reliance to be placed on the quantitative measurement.

With use of the measurement obtained, together with other hemodynamic data, the functional status of patients with mitral incompetence has been analyzed. The findings confirm that left ventricular failure, not mitral incompetence itself, underlies many of the criteria presently used to determine the severity of the disease, i.e., the presence of symptoms, the clinical and radiologic signs, and abnormalities in arterial dye dilution curves. These criteria are therefore probably not optimal ones on which to base selection of patients for surgical treatment, or to follow its results.

Cardiac output measurement by thermal dilution: reproducibility and comparison with the dye-dilution technique

Cardiac output estimates by the principle of thermodilution (COth) was compared with dye-dilution estimates (COdye) in pigs. For COth estimates a Swan-Ganz 7 F floating thermodilution catheter and a 9500 Edwards Computer, were used. The COdye estimates were obtained by the apparatus constructed by Zijlstra and Mook. The effect of the thermistor position in the pulmonary artery on the COth estimates was also investigated. The reproducibility of COth was examined by duplicate determinations. Based on 101 simultaneous estimates of COth and COdye the correlation was found COth = 1.020 COdye + 0.2378, r = 0.971 for cardiac outputs between 0.65 l/min and 11 l/min. For 111 duplicate determinations of COth between 2 and 9 l/min the coefficient of variation was 4.74%. The thermistor position in the pulmonary artery had no influence on the COth estimates provided an undamped pressure curve could be monitored from the tip of the catheter. Cardiac output can thus be measured rapidly with good accuracy also for low values by means of a blindly inserted thermistor catheter positioned without x-ray control and a computer with digital display.

Autonomic blockade by propranolol and atropine to study intrinsic myocardial function in man

Blockade of cardiac autonomic nervous activity by an intravenous injection of 0.2 mg/kg propranolol and 0.04 mg/kg atropine was used with cardiac catheterization to study intrinsic cardiac function in 47 patients with normal hearts and known graded myocardial disease. After blockade, significant hemodynamic abnormalities became apparent at rest in the majority of patients with known disease, many of whom had normal control findings. This occurred partly through a reduction in the normal range of cardiac function at rest, and partly through changes in the abnormalities associated with disease: after blockade, diseased hearts had normal stroke volumes, but beat more slowly, and had higher left ventricular filling pressures. The heart rate after blockade was fixed; this was defined as the intrinsic heart rate (IHR); it ranged from 57 to 126 beats/min in different patients. Both the IHR and left ventricular end-diastolic pressure after blockade were sensitively and quantitatively related to the severity of myocardial disease. When, after blockade, arterial pressure was raised by angiotensin, the IHR was unchanged; normal hearts maintained their stroke volume and increased stroke work; diseased hearts maintained stroke volume less well and stroke work was unchanged or fell. Abnormal ventricular responses corresponded well with abnormal ventricular function at rest. In different patients the IHR was significantly related to each available index of left ventricular function. Other studies in animals have shown that the IHR is closely related to intrinsic myocardial contractility in certain forms of experimental heart failure. An analogous relationship existing between the IHR and myocardial function in patients with heart disease is suggested as the explanation for the IHR/ventricular function relationship in this study. If so, the IHR may prove valuable as an index of myocardial function in man, since it can be measured simply and safely in clinical practice.

Quantitation of mitral regurgitation by constant infusion of xenon-133

A method for the accurate quantitation of mitral regurgitation in man was described and tested in 23 patients. The technique involves a constant infusion of xenon-133 into the left ventricle for 2 minutes. Left atrial and arterial samples must be withdrawn after constant concentration is achieved and before recirculation reaches high values. It was shown that concentration of indicator at both sample sites was constant by 60 seconds from the onset of infusion and that at 60 and 120 seconds left atrial concentration would rise on the average to 2.3 and 4.3% arterial concentration, respectively, as a result of recirculation. It could be demonstrated by altering the left atrial sample site that error due to incomplete mixing in the left atrium might average 2% and would be unlikely to exceed 7%. Values for cardiac output and regurgitant flow and regurgitant fraction, measured between 60 and 120 seconds, were relatively constant in any one patient. Regurgitant fraction varied from 1 to 84% of blood leaving the left ventricle in systole in different patients and there was good correlation with clinical and angiocardiographic estimates of severity of regurgitation.

Calculation of Cardiac Output from Indicator-Dilution Curves in the Presence of Mitral Regurgitation

Cardiac output was determined by the indicator-dilution technic with injection of indicator into the ascending aorta, left ventricle, and pulmonary artery in 13 cases of mitral incompetence and in 15 control cases (normal or mild valvular obstruction). The ascending aortic dye curve is not involved in mitral incompetence in its primary circulation and was used for comparison.

In normal subjects, there is no significant difference between the cardiac output obtained by injection of indicator into the ascending aorta and the left ventricle.

The cardiac output obtained from indicator-dilution curves affected by mitral regurgitation in its primary circulation is underestimated by approximately 20 per cent.

The effects of the coronary recirculated indicator particles on the disappearance slope would best explain the discrepancy. Even in the normal circulation, the inclusion of the coronary recirculated particles leads to a small underestimation of the cardiac output when the indicator is injected into the pulmonary artery.

The Pulmonary Blood Volume in Rheumatic Heart Disease and Its Alteration by Isoproterenol

Pulmonary blood volume was measured in five hemodynamically normal subjects and 37 patients with heart disease. Mean pulmonary blood volume in 25 of these patients with moderate to severe mitral stenosis, alone or complicated by other valvular lesions, was 359 ml. per M. 2 (SE = ±24 ml. per M. 2 ), which was significantly higher than the average value of 230 ml. per M. 2 (SE = ±14 ml. per M. 2 ) in the five normal subjects ( p < 0.025).

Multiple correlation of pulmonary blood volume with left atrial mean pressure, pulmonary vascular resistance, and stroke volume showed that each of these factors was significantly related to pulmonary blood volume, independently of the others. Increased left atrial pressure or stroke volume was associated with relatively high, and increased pulmonary vascular resistance with relatively low pulmonary blood volume.

In seven subjects 10 to 20 mg. of isoproterenol administered sublingually led to a marked increase in pulmonary blood volume and a small decrease in pulmonary vascular resistance. The average increase in pulmonary blood volume was 78 ml. per M. 2 , or 35 per cent of the control value (SE = ±15 ml. per M. 2 ), while the average drop in pulmonary vascular resistance was 1.3 R.U.M. 2 (SE = ±0.5 R.U.M. 2 ). Since the change in volume was too large to be accounted for by arteriolar dilatation alone, and there was a simultaneous decrease in pulmonary arterial and left atrial pressures, isoproterenol apparently increased the distensibility of a large but as yet unidentified segment of the pulmonary vascular bed.