Joseph L. Thorne

Brisket disease: II. Clinical features and hemodynamic observations in altitude-dependent right heart failure of cattle

Abstract In cattle grazing during the summer months at altitudes between 8,000 and 12,000 feet (2,500 to 3,700 meters) in Utah and Colorado severe congestive heart failure develops. The disease is apparently the consequence of severe pulmonary hypertension which develops in this species in response to moderate altitudes. This form of chronic mountain sickness has many similarities to pulmonary hypertensive heart disease in man. It differs from Monges disease in certain significant aspects. It is assumed that the peculiar structure of the pulmonary vascular bed in this species causes an excessive vasoconstrictive response at a reduction in partial pressure of oxygen which is still easily tolerated by man.

Hemodynamic effects of exercise in patients with aortic stenosis

Abstract Hemodynamic data obtained by right and left heart catheterization at rest and during exercise in thirty-two patients with aortic stenosis were reviewed. Eighteen patients had either minimal or no aortic regurgitation (group I) and fourteen patients had moderate to moderately severe aortic regurgitation (group II). The mean systolic pressure gradient (ΔP) across the aortic valve decreased or remained unchanged during exercise in eleven of eighteen patients in group I and in nine of fourteen patients in group II. Net forward aortic valve systolic flow (AVSF) increased during exercise in fourteen of eighteen patients in group I and in thirteen of fourteen patients in group II. Thus, in some patients the change in ΔP during exercise appears to be at variance with the predictability implied by the Gorlin equation which states that ΔP should be directly related to (AVSF) 2 . It is unlikely that this discrepancy can be explained on the basis of a systematic measuring error involving one or more of the various factors in the equation. This suggests that the aortic valve may not behave as a fixed orifice under all hemodynamic conditions, and that orifice hydraulics might be different depending on the mechanics of contraction. Average cardiac index (CI) was 2.5 L. per minute per M 2 . at rest and 3.8 L. per minute per M 2 . during exercise for patients in group 1, and 2.2 L. per minute per M 2 . at rest and 3.9 L. per minute per M 2 . during exercise for patients in group 2. Arterial and left ventricular systolic and diastolic pressures increased, and systemic resistance decreased during exercise. Thus, resting cardiac output is maintained and it increases during exercise at the expense of marked elevation in both systolic and diastolic pressures in the left ventricle. An analysis of the relationship between stroke work index (SWI) and left ventricular end diastolic pressure (LV edp ) in patients from group I revealed, in general, two types of responses to exercise. Six patients had an increase in SWI averaging 39 per cent associated with a 67 per cent increase in LV edp . In sharp contrast, ten other patients demonstrated an increase in SWI averaging only 1.3 per cent whereas LV edp increased by an average of 129 per cent. It is apparent therefore that the response to exercise makes it possible to separate patients with remaining myocardial reserve from those without. Thus, exercise data in patients with aortic stenosis provide objective, quantitative information useful in making a decision when and if to perform corrective surgery.

BRISKET DISEASE. III. SPONTANEOUS REMISSION OF PULMONARY HYPERTENSION AND RECOVERY FROM HEART FAILURE.

Previous reports from this laboratory have dealt with the ecologic, pathologic, clinical, and pathophysiologic features of brisket disease (1, 2). On the basis of these studies brisket disease may be defined as altitude-dependent, pulmonary, hypertensive heart disease in cattle of the species Bos taiurus. Briefly, the disease in Utah occurs primarily in young calves usually during their first exposure to conditions existing on summer ranges at elevations between 8,000 and 11,000 feet. Typical findings in animals suffering from brisket disease are outlined in Table 1. It was observed that a significant number of animals with acute brisket disease recovered when removed from the mountainous ranges and brought to Salt Lake City, Utah (elevation 4,500 feet). This observation prompted an investigation of the nature, magnitude, and time course of changes in various physiologic parameters associated with clinical recovery. The demonstration of dramatic remission from pulmonary hypertension and improvement in over-all cardiovascular function provides the basis for this report.

Clinical and physiologic sequelae of large ventricular septal defects.

Abstract The clinical and hemodynamic data in twenty-nine patients with large ventricular septal defects are analyzed. Evidence of heart failure is uncommon in those with pulmonary vascular disease and/or pulmonic stenosis alone, in contrast to those in whom certain other additional congenital lesions are present. These data are analyzed in terms of a physiologically single ventricle which exists when a large ventricular septal defect is present. Obligatory beat to beat synchronicity of the right ventricular and systemic arterial systolic pressure is discussed and its use in the diagnosis of the physiologically single ventricle in man outlined. Evidence is presented that in the face of a physiologically single ventricle, ventricular failure is most likely to occur when a volume or flow load is present in addition to right ventricular hypertension. The evolution and hemodynamic recognition of ventricular failure in the face of a physiologically single ventricle is discussed.

THE MURMUR OF TRICUSPID REGURGITATION AND THE “VENOUS PISTOL SHOT” SOUND IN BRISKET DISEASE OF CATTLE*

A hallmark of the advanced stage of pulmonary hypertensive heart disease in cattle (brisket disease) is the occurrence of striking functional tricuspid regurgitation which follows right ventricular distension when the altitude induced pulmonary hypertension characteristic of this disease has become excessive (see p. 649). The presence of this functional tricuspid incompetence is manifested by a characteristic holosystolic murmur replacing the first and second heart sound a t the apex, and a large positive pulse in the jugular veins. These findings are sufficiently pronounced to permit the diagnosis of Brisket disease in the field and to separate this entity from other forms of ascites or pericardial effusion in the bovine. FIGURE 1 demonstrates typical pressure records of an animal in an advanced stage of brisket disease. The right atrial pressure curve is nearly indistinguishable from those obtained within the right ventricle. In some cases, as is true of the tricuspid malformation of Ebstein’s disease in humans, the differentiation between the two positions is not possible, but the location of the tricuspid valve and therefore the transition from one chamber into the other can he identified only by simultaneously recorded endocardia1 electrocardiograms. As in the case of true mitral regurgitation in humans a predominant V wave all but dominates the atrial pressure record. An example of the influence of this form of tricuspid regurgitation on the shape of an indicator dilution curve has been published previously.’ ’’ The murmur is typically holosystolic, widely transmitted, and rather high pitched, blending with both the first and the second heart sound (FIGURE 2 ) . I t s point of maximum intensity is generally located just to the left of the sternum in the fifth intercostal space (position V of Detweiler, p. 323). Since the afflicted calves are tachypneic, the change in intensity of the murmur with respiration usually looked for in the human, was not observed. On recovery, when the animal is brought t o lower altitudes, the murmur disappears presumably with full return to the compensated cardiac state.

Comparison of Clinical and Hemodynamic Assessment of Cardiac Disability

Clinical versus hemodynamic assessment of cardiac disability was compared in 187 patients with either coronary artery or valvular disease classified using the New York Heart Association classification (excluding class IV). The following variables were analyzed during rest and exercise: arteriovenous oxygen content difference (CavO2), cardiac index (CI), pulmonary artery pressure (PAP), pulmonary artery wedge pressure (PAWP), pulmonary arteriolar resistance index (PARI) and heart rate (HR). 180 comparisons of variables were made. Hemodynamic evaluation paralleled clinical evaluation only 19 times during rest and 12 during exercise. There were 5 instances of clinical and hemodynamic distinction between class I and II, 14 between class I and III and 12 between class II and III. Correlation was best in mitral stenosis. The most useful variable was CI followed by PAP and CavO2. HR was not helpful. This study emphasizes that subjective clinical disability may not correlate with physiologic derangement in certain patients.