Myocardial blood flow in man: effects of coronary collateral circulation and coronary artery bypass surgery.

The effects of coronary artery bypass graft (CAB) and coronary collaterals (CC) on myocardial blood flow (MBF) were studied in 24 patients undergoing 29 CAB's. MBF after CAB was compared to preexisting MBF by intraoperatively injecting (133)xenon via distal CAB with proximal CAB first occluded then open. Pressure gradients across bypassed obstructions were measured. The results were correlated with preoperative coronary arteriograms to determine the effects of CC on MBF and postobstructive perfusion pressures. Mean MBF was increased by CAB from 32+/-6 (se) ml/min per 100 g (CAB occluded) to 118+/-13 ml/min per 100 g (CAB open). The (133)Xe clearance curves with CAB open were resolved into slow (19+/-2 ml/min per 100 g) and rapid (133+/-12 ml/min per 100 g) phases, suggesting that MBF remained heterogeneous after CAB. Vessels with less than 80% stenosis by angiography had pressure gradients less than 20 mm Hg across obstructions, high postobstructive perfusion pressures (75+/-7 mm Hg), and normal MBF (87+/-6 ml/min per 100 g) even with CAB occluded. Vessels with greater than 80% stenosis or total occlusion by angiography had significant pressure gradients with marked reduction of postobstructive MBF. No significant difference in postobstructive MBF was found when vessels with CC (21+/-4 ml/min per 100 g) were compared to those without CC (17+/-4 ml/min per 100 g) (P > 0.4). These studies demonstrate that (a) mean MBF increased 268% after CAB, (b) heterogeneous MBF persisted after CAB, (c) CC were not associated with significant increases in MBF, and (d) vessels with less than 80% stenosis had less than 20 mm Hg gradient with minimal effect on resting MBF.

Ventricular arrhythmias after coronary artery bypass graft surgery: incidence, risk factors and long-term prognosis.

The incidence, risk factors and long-term prognosis of complex ventricular arrhythmias after coronary artery bypass graft surgery are not known. Complex ventricular arrhythmias are defined as Lown grades 4a (couplets), 4b (ventricular tachycardia) and 5 (R on T phenomenon). Ninety-two patients with normal left ventricular function who underwent elective coronary artery bypass graft surgery were prospectively evaluated. Ventricular arrhythmias were documented by predischarge 24 hour ambulatory electrocardiographic monitoring; 43% of patients had no or simple ventricular arrhythmias (Lown grades 1 to 3) and 57% had complex ventricular arrhythmias. Risk factors analyzed included age, sex, diabetes, hypertension, smoking, preoperative digoxin or propranolol therapy, cardiopulmonary bypass time, aortic cross-clamp time, number of vessels bypassed, peak creatine kinase (CK) elevation and pericarditis. No risk factor identified patients at higher risk for complex ventricular arrhythmias. Patients were followed up for 6 to 24 months (mean 16). Patients with complex ventricular arrhythmias did not have a higher incidence of sudden death, cardiac death, syncope, angina, myocardial infarction or cerebrovascular accident. It was concluded that: Complex ventricular arrhythmias are common after coronary artery bypass graft surgery. None of the risk factors considered identify high risk patients. Complex ventricular arrhythmias after coronary artery bypass graft surgery do not indicate a poor prognosis in patients with normal left ventricular function.

Thrombolysis in Myocardial Infarction (TIMI) phase II trial: outcome comparison of a "conservative strategy" in community versus tertiary hospitals. The TIMI Research Group.

In the conservative strategy arm of phase II of the Thrombolysis in Myocardial Infarction (TIMI) trial, 1,461 patients were treated with intravenous recombinant tissue-type plasminogen activator (rt-PA). Coronary angiography, with angioplasty if feasible, was to be performed only for recurrent spontaneous or exercise-induced ischemia. In this study results in patients treated by this strategy in community and tertiary hospitals are compared. Despite similar baseline findings in the two groups, coronary angiography was performed within 42 days in more patients (542 [48%] of 1,155) initially admitted to a tertiary hospital (on-site coronary angiography/angioplasty available) than in those (94 [32%] of 306) admitted to a community hospital (transfer to tertiary hospital for coronary angiography/angioplasty) (p less than 0.001). This different approach resulted in a greater use of coronary angioplasty (203 [18%] of 1,155 versus 32 [11%] of 306, p less than 0.01), coronary artery bypass surgery (133 [12%] of 1,155 versus 23 [8%] of 306, p less than 0.05) and blood transfusions (139 [12%] of 1,155 versus 17 [5.5%] of 306, p less than 0.001) in patients admitted to a tertiary than to a community hospital. However, there were no significant differences between the two groups in mortality, recurrent myocardial infarction or left ventricular function. These results demonstrate that a conservative strategy after treatment of acute myocardial infarction with rt-PA is applicable in the community hospital setting.

Unsuspected giant cell arteritis diagnosed at open heart surgery.

A 62-year-old patient undergoing aortocoronary bypass grafting had giant cell arteritis diagnosed by routine aortic biopsy done at the graft insertion site. This finding led to the tissue diagnosis of temporal arteritis and the institution of steroid therapy. In retrospect, vague symptoms of headache and fatigue, which had been attributed to side effects of antianginal therapy, were probably caused by giant cell arteritis. The population undergoing aortocoronary bypass grafting is in an age group at risk for giant cell arteritis. Routine aortic biopsy specimens should be carefully examined with this in mind.

Left ventricular response to exercise and autonomic control mechanisms in end-stage renal disease.

Left ventricular (LV) function during rest and during exercise was evaluated in patients with end-stage renal disease (ESRD) in whom other causes of LV dysfunction were eliminated through rigid selection criteria. Autonomic function was also assessed in these patients with Valsalva's maneuver and plasma catecholamine determinations. Echocardiography and radionuclide ventriculography in the group with ESRD revealed no abnormalities of LV wall motion or ejection fraction. During graded exercise, patients with ESRD achieved 85% of age-predicted heart rate, and no differences in exercise tolerance or LV function were observed. Valsalva's response was abnormal in patients with ESRD, and post exercise the norepinephrine level was markedly increased (12.5 +/- 1.43 vs 8.28 +/- 0.82 nmol/L). Our results fail to indicate an independent adverse effect of ESRD on LV function.

Cardiopulmonary exercise testing. The clinical value of gas exchange data.

Cardiopulmonary exercise testing is a noninvasive tool whose clinical value is not yet widely recognized. The technique involves breath-by-breath measurement of respiratory gas exchange during a symptom-limited exercise test, with determination of maximal oxygen uptake and anaerobic threshold. These measurements serve as objective, reproducible indices of exercise capacity that can be applied to the management of various clinical problems. In addition, by permitting simultaneous assessment of circulatory and ventilatory reserves, the test can be especially helpful in the differential diagnosis of exertional dyspnea and fatigue. This paper reviews the physiology of gas exchange, the limitations of standard exercise tests, and the methodology and clinical applications of cardiopulmonary exercise testing.

Percutaneous transluminal coronary angioplasty of a coronary artery with a total occlusion.

Percutaneous transluminal coronary angioplasty has become an accepted therapeutic modality for patients with coronary artery disease. Until the present, its use has been restricted to vessels that are subtotally obstructed. We recently successfully utilized coronary angioplasty in a patient with a totally occluded coronary artery. The experience is described and criteria proposed for the selection of patients with totally obstructed coronary arteries for coronary angioplasty.

Hemodynamic evaluation of hydralazine dosage in refractory heart failure.

Hemodynamic responses to different doses of hydralazine were evaluated in 18 patients with severe refractory resistant heart failure. There were no significant overall hemodynamic effects after 50 mg hydralazine. After 75 mg, CI increased slightly (+0.36 l/min/m2) with a 19% decrease in SVR. After 100 mg, there were substantial increases in CI (+0.60 l/min/m2) and decreases in SVR (31%) changes which were greater than those after 75 mg, but the decrease in MAP with 100 mg (-6.6 mm Hg) was of the same order as that after 75 mg (-5.0 mm Hg). LVFP and SWI improved significantly only with 100-mg doses. Seven patients in whom 100 mg hydralazine induced no hemodynamic effects all responded to single doses of 150 to 200 mg. The duration of action of hydralazine was longer (p less than 0.001) in patients with a CCr less than 35 ml/min (14.3 +/- 1.4 hr) than in patients with adequate renal function (7.9 +/- 0.5 hr). Thus, the dose and dosing interval of hydralazine needed to induce hemodynamic improvement in patients with severe heart failure are variable and require individualization.

Left ventricular myxoma: echocardiographic diagnosis and review of the literature.

A 33 year old man with the findings of mild aortic stenosis had an echocardiographic diagnosis of left ventricular myxoma prolapsing through the aortic valve during each ventricular systole. The M-mode echocardiogram, B-scan ultrasonogram and angiograms of this patient are presented. The clinical characteristics in all the reported cases of left ventricular myxomas are reviewed.

Cardiac shape and function in aortic valve disease: physiologic and clinical implications.

Left ventricular shape and function were studied in 12 normal subjects, 18 patients with pressure overloading secondary to isolated aortic stenosis and 20 patients with volume overloading due to aortic regurgitation. End-diastolic volumes were mildly increased in aortic stenosis but greatly increased in aortic regurgitation. Average ejection fractions were normal in aortic stenosis but depressed in aortic regurgitation. Ventricular shape (eccentricity), normal (elongated) in nearly all patients with aortic stenosis, showed in diastole various degrees of abnormal roundness in patients with aortic regurgitation. As ventricular function declined in aortic regurgitation, the ventricles also became more round in systole. After valve surgery, clinical results were generally better in patients with aortic stenosis than in patients with aortic regurgitation. Among the latter, changes in eccentricity and ejection fraction were the best predictors of surgical outcome. It is postulated that chronic volume loading, as exemplified by aortic regurgitation, may induce basic alterations in architecture and fiber alignment of the left ventricular wall. Such changes may exert significant influence on the clinical course of these patients.

Differences in hemodynamic effects of nitroprusside and prazosin in severe chronic congestive heart failure: evidence for a direct negative chronotropic effect of prazosin.

To compare the hemodynamic effects of prazosin and nitroprusside in patients with severe congestive heart failure, nine patients with heart failure refractory to conventional therapy received oral prazosin and intravenous nitroprusside administered so as to produce a similar decrease in left ventricular filling pressure in each patient. By this comparison, both drugs produced similar decreases in mean right atrial pressure, mean pulmonary arterial pressure and systemic and pulmonary vascular resistance. However, with nitroprusside, cardiac index increased more (+0.97 versus +0.73 liters/min per m2, P less than 0.01) and mean arterial pressure decreased less (-13.7 versus -18.3 mm Hg, P less than 0.05) than with prazosin. Both drugs produced similar changes in stroke volume index (+11.7 cc/beat per m2 with nitroprusside and +12.5 with prazosin) and stroke work index (+8.1 g-m/m2 with nitroprusside and +6.6 with prazosin). Therefore, the differences in the hemodynamic responses observed with the two agents were due to the significantly greater decrease in heart rate with prazosin (-8 beats/min) than with nitroprusside (-2 beats/min, P less than 0.05). These clinical data support experimental evidence suggesting that there is a significant negative chronotropic action of prazosin independent of its peripheral vascular effects.

Shunt flow and pulmonary hemodynamics during labor and delivery in the Eisenmenger syndrome.

The Eisenmenger syndrome carries a high mortality rate in a women during delivery and the immediate postpartum period. It has been suggested that marked changes in shunt flow and pulmonary hemodynamics may be responsible. These functions were studied under various physiologic and pharmacologic conditions during labor and delivery in a patient with the Eisenmenger syndrome. Uterine contractions were associated with a decrease in the ratio of pulmonary to systemic blood flow (Qp/Qs) from 1.58 to 1.05. The Qp/Qs ratio also decreased (to 0.83) when forceps were applied during uterine contractions. Epidural anesthesia, oxytocin and the supine position did not adversely affect pulmonary hemodynamics or shunt flow. On the basis of these results, if pregnancy cannot be terminated in a patient with the Eisenmenger syndrome, it is recommended that the patient be given high concentration of oxygen and epidural anesthesia and that serial arterial blood gas determinations be performed to detect changes in shunt flow.

Correlations of electrocardiography and echocardiography in determination of left ventricular wall thickness: Study of apparently normal subjects.

To examine the usefulness of the surface electrocardiogram in predicting left ventricular wall thickness as determined with echocardiography, standard echocardiograms, electrocardiograms and Frank lead vectorcardiograms were obtained in 30 volunteers. End-diastolic thickness of the interventricular septum and free posterior wall was measured from the echocardiogram and compared with the sum of the S wave in lead V1 plus the R wave in lead V6 (VS1+R6) and the magnitude of the Frank lead vector (Vf), a scalar dunction obtained from a simple analog device. The maximum of Vf, the summated vector (Vf), was highly correlated with VS1+R6 (r=0.84). There was significant correlation between the summated vector and VS1+R6 and the thickness of the interventricular septum (IVS) (r=0.73 and 0.66, respectively). The best least mean square fit for the population was Vf=1.7 IVS-0.39. There was no significant correlation between these variables and the end-diastolic thickness of the posterior wall. Volunteers who were athletically inclined or were joggers tended to have larger summated vector values and evidence of symmetric or asymmetric left ventricular hypertrophy in the echocardiogram. It therefore appears that the thickness of the interventricular septum has a greater influence on the summated vector and VS1+R6 that the echocardiographically assessed thickness of the free posterior wall of the left ventricle. The implications of these findings in the light of recent reports about the incidence of echocardiographically diagnosed left ventricular hypertrophy are discussed.

Problems in echocardiographic volume determinations: echocardiographic-angiographic correlations in the presence of absence of asynergy.

The relation of minor and major axes of the left ventricle was determined in 100 left ventriculograms performed in the right anterior oblique projection. This relation taken over a wide range of volumes was used to derive a theoretically correct equation for determination of ventricular volume by echocardiography. The final equation was: V =[7.0/2.4 +d] (D3), where V = volume and D = the echocardiographically measured internal dimension. In 12 patients without asynergy, this equation accurately and directly calculated end-systolic and end-diastolic volumes whether the left ventricle was small or large. However, in 12 patients exhibiting left ventricular asynergy the correlation between angiographically and echocardiographically determined volumes was poor. Thus, caution is recommended in the use of time-motion echocardiography to calculate ventricular volumes in patients with coronary artery disease and possible left ventricular asynergy.

Dermatoglyphic patterns in patients with mitral valve prolapse: a clue to pathogenesis.

Fingerprints were obtained from 100 patients with mitral valve prolapse and compared with those of 100 control subjects matched for sex and race. Arches were found in 16.8 percent of all digital patterns in patients with mitral valve prolapse but in only 2.5 percent of all digits in the control group. Whereas no patient in the control group had four or more arches, 19 percent of patients with mitral valve prolapse had this finding. In addition, arches were found on 16 and 9 percent, respectively, of digits IV and V in patients with mitral valve prolapse but were not found on these digits in the control group. The finding of four or more arches or arches on digits IV or V may be important supportive evidence of mitral valve prolapse when evaluating patients with atypical chest pain and palpitations. Antenatal factors may be involved in the pathogenesis of mitral valve prolapse since it is possible that a genetic or environmental factor that interferes with the development of the mitral valve may also influence epidermal ridge patterns.

Echocardiographic diagnosis of left anterior descending coronary artery disease.

To determine the usefulness of the standard echocardiogram in the diagnosis of left anterior descending coronary artery disease proximal or distal to the first septal branch, coronary arteriograms and echocardiograms were performed in 77 patients with a chest pain syndrome. Seventy-nine percent of patients with proximal disease (15 of 19) had an abnormal septal motion measured as a posterior wall/interventricular septal (PW/IVS) excursion ratio greater than or equal to 2.5 compared with 10% of patients with distal disease (2 of 20) who had abnormal septal motion. Only 5% of patients without obstructive disease of the left anterior descending coronary artery (2 of 38) had abnormal septal motion. Proximal disease was found in 79% with abnormal septal motion in the echocardiogram (15 of 19) but in only 7% of patients with normal septal motion (4 of 58). Therefore, abnormal septal motion as measured by the PW/IVS excursion ratio in the echocardiogram is a useful index for the diagnosis of disease of the left anterior descending coronary artery when that disease is proximal to the first septal branch.

Abnormalities of left ventricular function and geometry in adults with an atrial septal defect. Ventriculographic, hemodynamic and echocardiographic studies.

Left ventricular function and motion in 12 adults with an ostium secundum atrial septal defect were analyzed utilizing biplane cineangiography. Values for left ventricular end-diastolic volume index, stroke volume index, ejection fraction, left ventricular end-diastolic pressure and mean rate of circumferential fiber shortening were compared with values in an age-matched group of 11 normal subjects. Comparisons of ventriculographic and echocardiographic data were also made in 5 patients and 10 control subjects. Cardiac index was smaller in patients than in the normal subjects (3.6 vs. 4.5 liters/min per m2, P less than 0.01). Although left ventricular end-diastolic pressure was similar (8 mm Hg in both groups), the end-diastolic volume index was significantly smaller in patients than in normal subjects (56 vs. 76 ml/m2, P less than 0.05). Stroke volume index was also significantly smaller in patients (40 vs. 52 ml/m2, P less than 0.01). The two groups had similar values for ejection fraction (65 +/- 2 percent [standard error of the mean] in patients vs. 68 +/- 2 percent in normal subjects), circumferential fiber shortening velocity (1.67 +/- 0.13 vs. 1.81 +/- 0.15 circumferences/sec.), heart rate (91 +/- 7 vs. 90 +/- 5 beats/min) and mean systemic arterial pressure (92 +/- 5 vs. 87 +/- 3 mm Hg). Early systolic bulging of the upper ventricular septum toward the right ventricle was seen in 10 of 12 patients with an atrial septal defect but in no normal subject. Echocardiographic data supported these findings. No other abnormalities of motion were consistently noted. It is concluded that the left ventricle of patients with an atrial septal defect is subnormal in volume and abnormal in sequence of contraction of the septum and is characterized by apparent decreased distensibility.

Septal perforator compression (narrowing) in idiopathic hypertrophic subaortic stenosis.

Thirteen patients with idiopathic hypertrophic subaortic stenosis were compared with two groups of subjects: 10 patients with chest pain, normal coronary arteries and a normal left ventricle, and 10 patients with left ventricular hypertrophy. Five of the latter had aortic stenosis and five had idiopathic left ventricular hypertrophy. Coronary arteriography revealed that the septal branches of the left anterior descending artery closed or narrowed during systole in patients with idiopathic hypertrophic subaortic stenosis and did not do so in the other patient groups. This narrowing is possibly related to an abnormal position of the septal arteries within the septum in idiopathic hypertrophic subaortic stenosis. Systolic compression of the septal perforator arteries is not a pathognomonic sign of idiopathic hypertrophic subaortic stenosis.

Paradoxical motion of the interventricular septum with right ventricular dilatation in the absence of shunting: report of two cases.

A history, heart murmur, electrocardiogram and chest X-ray film suggesting an atrial septal defect associated with an echocardiogram revealing paradoxical motion of the interventricular septum with a dilated right ventricle may be considered indicative of a secundum or primum defect in a young adult or child. Two patients who fulfill all these criteria and had the presumptive diagnosis of an atrial septal defect were found at cardiac catheterization to have no demonstrable left to right shunt or other significant abnormality. The results of standard T-M mode echocardiograms were verified with B scan ultrasonograms. These cases may represent an early stage in the development of a cardiomyopathy. There is no echocardiogram pathognomonic of an atrial septal defect, and patients whose history and echocardiogram suggest this defect should have further diagnostic evaluation including technetium scan or cardiac catheterization.

Can noninvasive exercise test criteria identify patients with left main or 3-vessel coronary disease after a first myocardial infarction?

This study attempts to determine whether exercise treadmill testing with clinical, electrocardiographic, and thallium-201 myocardial perfusion imaging data can identify which patients have left main or 3-vessel (anatomically high-risk) coronary artery disease (CAD) after their first transmural myocardial infarct (MI). Twelve exercise test criteria for high-risk disease were compared in 40 patients referred for cardiac catheterization; 34 had a history of chest pain and 17 had angiographically defined high-risk CAD. A thallium image defect outside the vascular distribution of the MI was the most reliable criterion to distinguish patients with high-risk CAD (p = 0.00052 for Fisher's exact test of discrimination). Thallium imaging was somewhat more sensitive (92 versus 65%, p = 0.108) when patients with negative thallium imaging criteria who failed to achieve 85% of the age-predicted maximal heart rate were excluded. Failure to achieve 85% of predicted heart rate was by itself a useful criterion for detecting high-risk CAD (p = 0.017), especially in patients not taking propranolol (p = 0.004). Development of positive S-T segment depression at less than 70% predicted heart rate also discriminated left main or 3-vessel disease from less extensive CAD (p = 0.016). Other criteria failed to discriminate significantly between high-risk and less extensive CAD in patients after their first MI (p greater than 0.05). S-T segment depression (p = 0.199) or chest pain (p = 0.577) during exercise testing were particularly unreliable. Further, none of the criteria for high-risk CAD were influenced by irreversible left ventricular dysfunction. It is concluded that patients with thallium imaging defects outside the region of the infarct, decreasing blood pressure during exercise, failure to achieve 85% of predicted heart rate, or S-T depression at less than 70% of predicted heart rate have a high probability of having left main or 3-vessel disease. Patients without these criteria have a very low probability of having high-risk CAD and probably do not need coronary angiography for the purpose of excluding these high-risk coronary lesions after a first MI.