Demonstration of an inadvertently created aorto-coronary venous anastomosis: evidence against the clinical effectiveness of retrograde coronary venous perfusion

Arterilization of the coronary venous system has been suggested as a means of myocardial perfusion. We recently studied a patient with a saphenous vein aorto=coronary venous bypass graft created inadvertently during surgery intended to bypass the anterior descending artery. We selectively injected onctrast into this graft during balloon occlusion of the coronary sinus both before and after sublingual nitroglycerin. No arterial visualization was demonstrated from the vein and no evidence to suggest perfusion of the myocardium was found.

Effect of sublingual nitroglycerin on regional flow in patients with and without coronary disease

We evaluated the effects of sublingual nitroglycerin on indices of regional coronary flow and coronary resistance (CR) in 12 selected patients with coronary artery disease (CAD) and eight with normal coronary arteries (NCA), using continuous thermodilution. Resting total left ventricular flow, reflected by coronary sinus flow (CSF), and anterior regional flow, reflected by great cardiac vein flow (GCVF), in NCA and CAD patient groups, were similar. However, in a subgroup of six patients, with CAD limited to the anterior descending artery, GCVF was lower and anterior regional CR (CRANT) higher than the NCA subjects. Nitroglycerin reduced the systolic pressure-heart rate product similarly in both patient groups. CSF and GCVF in NCA subjects declined 15% and 17%, respectively, as total CR (CRT) and CRANT increased. In the CAD subgroup, consisting of patients with CAD limited to the anterior descending, GCVF increased 48% as CRANT declined 50%, and CSF was unchanged. In the other CAD subgroup of patients with CAD in the right and/or circumflex arteries, GCVF declined 32% and CRANT increased 46% as CSF was minimally increased. These data imply that sublingual nitroglycerin reduces both CSF and GCVF in NCA patients as oxygen demands decrease. In certain CAD patients, however, nitroglycerin alters regional coronary venous blood flow, suggesting a redistribution of flow from normally perfused to hypoperfused regions.

In vivo validation of a thermodilution method to determine regional left ventricular blood flow in patients with coronary disease

Several methods have been used to measure left ventricular regional blood flow in humans. However, limitations and lack of validation in patients are major problems. A continuous thermodilution technique to measure regional left ventricular blood flow in patients with coronary disease was validated in vivo. This technique permits simultaneous assessment of venous blood flow draining predominantly from the anterior wall and of the total left ventricular effluent. Thermodilution measurements with simultaneous electromagnetic flowmeter recordings from anterior descending vein grafts were compared in patients with occluded or subtotally occluded anterior descending coronary arteries. The thermodilution method yielded values for both absolute anterior regional blood flow and changes in anterior regional flow that compared closely to anterior descending bypass graft flow measured independently. The multithermistor technique may be useful in monitoring flow effects of regional coronary disease over time, as well as in studies of agents purported to alter regional blood flow.

Coronary and myocardial metabolic effects of combined glyceryl trinitrate and propranolol administration. Observations in patients with and without coronary disease

Coronary haemodynamic and metabolic effects of propranolol and glyceryl trinitrate were studied in 12 patients with coronary artery disease and 5 without coronary heart disease, at rest and during tachycardia stress. Propranolol-associated reductions in indices of myocardial oxygen demand, left ventricle work, tension time, and left ventricle oxygen utilisation (LVVO2) were reversed when heart rate was controlled by atrial pacing. Adding glyceryl trinitrate at rest also restored heart rate but decreased the left ventricular work index and tension time index as coronary resistance declined paradoxically. Tachycardia-related increases in tension time index and LVVO2 were unchanged after propranolol, and ischaemia (angina, ST depression, and reduced lactate extraction) was not altered in most of the patients. During tachycardia, the addition of glyceryl trinitrate decreased the tension time index and LVVO2; angina recurred in only 4 patients, and ST depression and lactate extraction improved. Similar haemodynamic changes occurred in the patients with normal coronary arteries. In contrast with propranolol administered alone, propranolol plus glyceryl trinitrate enhances tachycardia tolerance and prevents tachycardia-induced manifestations of ischaemia. This action is attributed to glyceryl trinitrate-associated improvement in the adequacy of myocardial perfusion.

Platelet aggregation in aortic and coronary venous blood in patients with and without coronary disease. 3. Role of tachycardia stress and propranolol

We studied 16 patients with coronary artery disease (CAD) to evaluate platelet aggregation in blood samples withdrawn simultaneously from the aorta and coronary sinus. At rest, mean platelet aggregation in coronary venous blood was significantly lower than that in aortic blood. Platelet counts in coronary venous blood were also lower than in the aortic blood in each of the six CAD patients in whom counts were done. Platelet aggregation was lower in seven patients who were taking propranolol than in the remaining nine who were not taking propranolol. During tachycardia stress, platelet aggregation increased in all patients, but the magnitude of increase was greater in patients not taking propranolol. In four other patients without CAD, platelet aggregation and counts were also studied in the same fashion and were similar in both the aortic and coronary venous blood. These data suggest that in certain CAD patients, platelet consumption or destruction within atherosclerotic vasculature may occur. Propranolol may reduce platelet aggregation at rest and modify excessive aggregation during tachycardia stress in certain CAD patients.

Platelet aggregation studies in coronary artery disease. Past 4. Effect of aspirin

We evaluated platelet aggregation in vitro in blood samples drawn simultaneously from aorta and coronary sinus. Platelet aggregation was significantly lower in the coronary venous blood than in the aortic blood in patients with coronary artery disease. Lower platelet counts were also observed in coronary venous blood. No such differences were seen in subjects with normal coronary arteries. Oral administration of aspirin eliminated the differences in platelet aggregation and counts across the myocardial vascular bed. These observations suggest that platelet sequestration in the myocardial vasculature may be related to the presence of disease in the coronary arteries.

Unusual vasomotor coronary arterial responses after nitroglycerin

Angiographic evidence of unusual vasomotor responses occurred in two patients after administration of sublingual nitroglycerin. In these patients, right coronary arterial segments that appeared angiographically normal before the administration of nitroglycerin showed narrowing after nitroglycerin. Adjacent segments in each of these vessels, as well as the other coronary arteries, dilated as expected. Both patients remained asymptomatic. Repeated administration of nitroglycerin did not alter the anglographic appearance of these vessels. No reason for the localized reduction of coronary arterial diameter was apparent. The possibility that nitroglycerin was associated with these unusual changes is an additional argument against the routine administration of nitrates before coronary arteriography.

Hemodynamic effects of long and multiple coronary arterial narrowings

The coronary hemodynamic influence of a series of coronary arterial narrowings was compared with single narrowings of the same total length and reduction in diameter in 12 dogs. Compared with single narrowings, two or three sequential narrowings had no significant effect on restng coronary blood flow. Small but significant mean pressure gradients were found for series of two and three 1-mm narrowings but not for single narrowings of the same total length. During reactive hyperemia, repayment of the debt in flow decreased significantly for single 2-mm and 3-mm narrowings, compared with 1-mm single narrowings. An additional decrease in repayment of the debt in flow occurred for two and three separate narrowings, compared with single narrowings. Our findings imply that when the reduction in the diameter of the coronary artery is fixed, an increase in the length or number of narrowings in series reduces the responses of coronary blood flow during reactive hyperemia.

Percutaneous left ventricular catheterisation with an ultraminiature catheter-tip pressure transducer

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.

Aneurysm of sinus of Valsalva: cause of dynamic coronary constriction after aortic valvular replacement and bacterial endocarditis

A patient who had endocarditis on a prosthetic aortic valve and who had undergone two aortic valvular replacements developed classic angina pectoris. Cardiac catheterization revealed an aneurysm of the left sinus of Valsalva, which constricted a proximal segment of the left circumflex coronary artery during systole. This type of dynamic coronary arterial narrowing has not been previously described secondary to an aneurysm of a sinus of Valsalva and may be responsible for this patient's manifestations of ischemia.

Pulsatile flow characteristics of aortic valve porcine heterografts in man

Pulsatile flow characteristics in the ascending aorta were examined in 14 patients 12 months after aortic valve replacement with the glutaraldehyde-fixed porcine aortic heterograft. Analysis of the velocity signals permitted measurement of peak velocity, maximal acceleration, stroke volume, and ejection time in addition to the standard measurement of systolic aortic valvar gradient. Angiographic techniques permitted visualization of a pattern of blood flow in the ascending aorta. Valvar aortic gradients were minimal, and, when the phasic ascending aortic blood flow velocity parameters were compared to those in a group of eight patients with normal aortic valves, these characteristics of flow were nearly indistinguishable. This remarkable similarity to the flow characteristics of normal valves may be important to long-term performance of a prosthetic aortic valve. Our results suggest that the glutaraldehyde-fixed porcine heterograft warrants serious consideration when selecting a substitute aortic valve for man.

Aortic input impedance in heart failure

The input impedance of the systemic circulation was calculated from recordings of pulsatile pressure and flow in the ascending aorta of 20 patients. Ten patients had clinical and hemodynamic evidence of heart failure. The other 10 subjects had no clinical evidence of heart failure and were used as a control group. In the heart failure patients, both input resistance and characteristic impedance (index of aortic distensibility) were significantly increased compared to pressure- and age-matched control subjects. Oscillations of impedance moduli, represented by the difference between maximum and minimum moduli, were also significantly increased in the heart failure patients compared with the control subjects. The increased characteristic input impedance in these heart failure patients suggests that the human aorta is stiffer in heart failure, and the larger oscillations in the impedance spectrum indicate an increase in pressure and flow wave reflections. From reflected wave theory in elastic tubes, reflected pressure waves add to the amplitude of incident pressure waves at the entrance of the system, whereas reflected flow waves subtract from the magnitude of the forward flow. Thus, changes in aortic distensibility could have an important influence on the pulsatile function of the failing left ventricle.

Differences in platelet aggregation in coronary sinus and aortic blood in patients with coronary artery disease: effect of propranolol

Platelet aggregation was studied in aortic and coronary sinus blood samples obtained from 18 patients with coronary artery disease (CAD). Using epinephrine and ADP as aggregating agents, platelet aggregation was lower in coronary venous blood than in aortic blood. In nine patients on long-term propranolol therapy, platelet aggregation was lower in both aortic and coronary venous blood compared to the nine patients not taking propranolol. Four other subjects without angiographic evidence of coronary disease exhibited no difference in platelet aggregation in aortic and coronary sinus blood. These data suggest that platelet aggregation is lower in the coronary venous blood of certain patients with coronary disease and chronic propranolol treatment may reduce aggregation in both aortic and coronary sinus blood.

Haemodynamic effects of hydrallazine and of hydrallazine plus glyceryl trinitrate paste in heart failure

In a study designed to investigate potential non-parenteral treatment for chronic heart failure, hydrallazine, 225 to 300 mg per day, was given orally to 9 patients. There was no significant change in heart rate or mean arterial pressure as cardiac output increased. Left ventricular stroke work increased significantly and pulmonary artery wedge pressure fell. Systemic and pulmonary vascular resistances fell. With the addition of 2 per cent glyceryl trinitrate paste, there was a further decline in mean pulmonary arterial and wedge pressures, without a significant change in heart rate, arterial pressures, cardiac output, or systemic or pulmonary vascular resistance. There were no untoward effects from either form of treatment. All patients reported relief of shortness of breath and other symptoms related to ventricular dysfunction. This study supports the suggestion that oral hydrallazine is effective in increasing cardiac output and decreasing pulmonary congestion. Furthermore, the addition of topical glyceryl trinitrate provides a greater reduction of pulmonary pressures, probably through its predominant venodilator action. In some selected patients with heart failure, oral hydrallazine and topical glyceryl trinitrate in combination produce beneficial clinical and haemodynamic effects, probably through afterload and preload reduction, respectively.

Non-parenteral combined afterload and preload reduction therapy in congestive heart failure

It has been shown that hydralazine is beneficial in chronic heart failure by virtue of its afterload reducing effect. Nitroglycerin paste results in venodilation and fall in left ventricular filling pressure (LVFP). Thirteen patients with chronic heart failure were given a combination of oral hydralazine and nitroglycerin paste. With oral hydralazine (75 to 100 mg every 8 h), left ventricular stroke work increased and LVFP slightly fell. Following addition of 2% nitroglycerin paste, an additional decline in mean pulmonary artery and LVFP was observed without significant changes in heart rate and arterial pressure. There were no untoward side effects from either therapy. Eight patients followed for three to eight months (mean five months) reported subjective improvement in shortness of breath and other symptoms related to ventricular dysfunction. This study shows that in certain patients with chronic heart failure, hydralazine and nitroglycerin paste combination produces salutary clinical effects on long term probably through afterload and preload reduction, respectively.

Hemodynamic significance of the length of a coronary arterial narrowing

The hemodynamic significance of the length of a coronary arterial narrowing is unclear. Accordingly, the influence of the length of a given coronary narrowing on coronary hemodynamic responses was studied in 14 dogs. Recordings were made as short fixed diameter reductions were progressivley lengthened to 5, 10 and 15 mm by the addition of plastic occluders. Resting coronary blood flow decreased and pressure gradients developed across short (snare) narrowings greater than 80 percent (critical stenosis). Short 40 to 60 percent narrowings had no significant resting hemodynamic influence, but increasing their length to 10 and 15 mm consistently resulted in significant pressure gradients and flow reductions. Reactive hyperemic coronary blood flow expressed as repayment of flow debt (after 10 seconds of coronary occlusion) decreased progressively as these narrowings were lengthed. The effect of 15 mm long narrowings on resting and reactive hyperemic flows was similar to that of short 90 percent narrowings. These data indicate that there is uncertainty about the significance of coronary diameter reductions previously considered hemodynamically unimportant. In our studies, significant changes in resting and reactive hyperemic coronary flows and resting pressure gradients occurred as the length of a given degree of narrowing was increased.

Ergonovine testing for coronary artery spasm in patients with angiographic mitral valve prolapse

Coronary artery spasm (CAS) has been postulated to be a pathophysiologic mechanism in the production of ischemic-like chest pain and ECG changes in patients with idiopathic mitral valve prolapse syndrome. To evaluate the possible role of symptomatic CAS evoked by ergonovine maleate, this agent was administered (0.05 to 0.4 mg IV) to 24 patients with chest pain and mitral valve prolapse who had no significant (less than 50%) coronary artery obstruction. Symptoms, ECG and blood pressure changes were monitored in all patients following ergonovine administration. No significant changes were observed in heart rate, systolic blood pressure, or double product. Six patients developed their typical chest pain. In two of these six with chest pain, ST segment shift greater than 1 mm were seen. Post-ergonovine left ventricular end-diastolic pressure (LVEDP) and coronary angiographic changes were also studied in subgroup of 12 of these patients, including five of the six chest pain responders. In the five chest pain responders, pain was associated with a significant rise in LVEDP, whereas no significant change occurred in those patients not experiencing chest pain (p less than 0.01). Chest pain was also associated with significant CAS (greater than 50% lumen reduction) in two patients, each with ST segment shifts greater than 1 mm. In summary, ergonovine stimulation failed to evoke symptoms, ECG or blood pressure changes in three quarters of mitral valve prolapse patients studied. Six patients developed chest pain. Chest pain was assoicated with ECG changes characteristic of CAS in two of these patients, each with angiographic CAS. Thus, symptomatic CAS induced by ergonovine was absent in the majority of these 24 patients with idiopathic mitral valve prolapse syndrome.

Coronary circulatory effects of increased intrathoracic pressure in intact dogs

The effect of increased intrathoracic pressure on coronary hemodynamics and coronary venous oxygen tension was evaluated in surgically instrumented dogs. Following abrupt increase in intrathoracic pressure, as systolic pressure decrease, the tension time index (TTI) fell 83 percent (P less than 0.001) compared to control. The diastolic pressure time index (DPTI) decline proportionately less, effecting an increase in the ratio of DPTI/TTI from 1.19 +/- 0.08 to 1.78 +/- 0.16 (P LESS THAN 0.05). The mean circumflex coronary blood flow declined only minimally toward the end of the test (5.1 +/- 9.0 ml/min; P less than 0.05), and stroke systolic circumflex coronary blood flow increased 116 percent (P less than 0.01) as late diastolic coronary resistance decreased 31 percent (P less than 0.01). The mean coronary venous oxygen pressure increased transiently above control values from 21 +/- 1 to 24 +/- 2 mm Hg (P less than 0.05). These data suggest that in anesthetized dogs, brief periods of high intrathoracic pressure abruptly reduce determinants of myocardial demand for oxygen, while myocardial perfusion decreases to a lesser degree.

Transient asymptomatic S-T segment depression during daily activity

The significance of asymptomatic episodes of ischemic type S-T segment depression was studied in 20 patients with coronary heart disease. Continuous 10 hour electrocardiographic recordings accompanied by detailed daily diaries of activity and symptoms were obtained periodically during a mean time of 16 months. All patients had ischemic type S-T depression associated with angina pectoris during treadmill exercise. Measurements of heart rate, S-T depression and exercise level at the onset of angina obtained during repeated controlled exercise tests at the start of each study period were compared with the measurements recorded during daily activity. After 2,826 hours of recording, 411 transient epidsodes of ischemic type S-T depression were noted during usual daily activity. Only 101 (25 percent) of these episodes were associated with angina. The remaining episodes were unrelated to other symptoms or to posture. All occurred at heart rates significantly lower than those observed at the onset of angina during exercise testing. Of these episodes of asymptomatic S-T depression, 72 percent occurred only at rest or during very light activity such as slow walking or sitting. Nitroglycerin administered hourly significantly reduced the frequency of these episodes, thus supporting the concept that they represent painless ischemia. Because the episodes of asymptomatic ischemic type S-T depression occurred more frequently than angina during usual daily activity and were evident at heart rates and activity levels well below those expected to evoke ischemia, they may be caused by factors other than those that cause angina.

Effects of propranolol on coronary hemodynamic and metabolic responses to tachycardia stress in patients with and without coronary disease

To clarify the influence of propranolol-and particularly its heart-rate effects-on myocardial ischemia, coronary hemodynamics and metabolism were studied in 15 patients utilizing a protocol to control heart rate. Ten patients had significant coronary narrowing (CAD) and 5 were normal. Systemic pressure, coronary sinus blood flow (CSBF), left ventricular oxygen utilization (LVVO2), ST Segment depression, and myocardial lactate extraction were measured before and after propranolol (10 mg IV), at rest, during pacing-induced tachycardia stress. Propranolol-related reduction in CSBF and LVVO2 at rest was reversed when heart rate was controlled in both patient groups. Propranolol failed to alter heart-rate threshold, tension-time index (TTI), CSBF, or LVVO2 at angina in the CAD patients. Likewise, ischemic-type ST depression, decreases in lactate extraction, and coronary resistance were unchanged compared to values observed during tachycardia stress before propranolol. In normal coronary patients, propranolol also produced no significant change in LVVO2 or coronary resistance when its heart rate effects were controlled. These data imply that a major coronary and metabolic influence of propranolol relates to changes occurring secondary to its influence on heart rate. Furthermore, this agent's anti-ischemic effect is not prominent during tachycardia stress suggesting that this stress test may be clinically useful in patients taking propranolol.