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Biomedical subjects

C R Conti

Publications and source records attributed to C R Conti.

At least 379 records · Page 21Linked to original sources
PubMed1978

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.

Animals↗
PubMed1978

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.

Adult↗
PubMed1978

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.

Adult↗
PubMed1978

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.

Administration, Oral↗
PubMed1978

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.

Cardiac Catheterization↗
PubMed1978

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.

Adult↗
PubMed1978

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.

Adult↗
PubMed1978

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.

Animals↗
PubMed1978

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.

Adult↗