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Hemodynamic correlates of coronary blood flow and myocardial oxygen consumption during upright exercise
ABSTRACTS
It is concluded that the rapid heart rates resulted in reduced dimensions of the RV outflow tract so that Qp decreased and R-L shunt and cyanosis increased. PAT should be added to the list of conditions that can precipitate cyanotic spells in some patients with T/F. Other supraventricular tachycardias may produce similar results.
Hemodynamic Correlates of Coronary Blood Flow and Myocardial Oxygen Consumption During Upright Exercise KAZUTO KITAMURA, MD; CHARLES R. JORGENSEN, MD; FREDARICK L. GOBEL, MD; HENRY TAYLOR, PhD;YANG WANG, MD, Minneapolis, Minnesota
This study was designed to evaluate hemodynamic indexes that are easily measurable, in some cases noninvasive, and that might have predictive value for myocardial oxygen consumption (MqO,) during various levels of upright exercise up to heavy exertion. Ten healthy male volunteers in their 20’s were studied. Catheters were placed in the ascending aorta and coronary sinus. Upright bicycle exercise was done at several levels to produce heart rates in the ranges of 100-110, 140-150 and 160-175 beats/min, and the following measurements were made: heart rate (HR) , blood pressure (BP), coronary blood flow (CBF) by the nitrous oxide saturation method, and A-V OZ difference. Modification of the CBF method was necessary to measure flows of the magnitude encountered. HR alone correlated well with CBF (r = 0.82) and MqO, (0.88). The correlation of HR x systolic BP with CBF (0.87) and MqO, (0.90) was even better. The tension-time index correlated less well with CBF and MqO, (0.83 and 0.77)) and the external work load was an even poorer correlate. It is concluded that heart rate can provide a useful standardization of cardiac stress for such purposes as exercise electrocardiography.
Perfusion Pressure and Myocardial Blood Flow SUZANNE McHENRY,
B. KNOEBEL, MD; LEON STEIN, MD, Indianapolis, Indiana
MD;
PAUL
L.
The concept that coronary blood flow (MFB) is perfusion pressure-dependent in patients with coronary artery disease (CAD) has had significance in consideration of therapy in this disease. To study the relation of MFB and perfusion pressure, 2 studies were undertaken. Shock was produced in 22 dogs by coronary embolization. The dogs were divided into 3 groups, Group 1 (untreated) ; Group 2 (isoproterenol [ISUI, 0.02-0.09 pg/kg per min) ; and Group 3 (norepinephrine [NE], 0.3-1.1 pg/kg per min). MBF, utilizing a coincidence counting-single bolus 84RbC1 technique, and mean, diastolic and systolic mean arterial pressures were measured 1 hour after embolization. NE and ISU resulted in significant (P
VOLUME
26,
DECEMBER
1970
A second study was performed in 60 patients with cinearteriographically proved CAD. MBF and arterial pressures were measured as in the dog study. There was no correlation through the third degree polynomial in analysis of variance between MBF and any of the arterial pressure changes with isoproterenol infusion (5 pg/min). The lack of correlation maintained for all degrees of severity of CAD as graded by percent of vessels remaining open. The MBF in patients with the most severe degree of coronary occlusive disease (45 or less of vessels remaining patent) was no more dependent on perfusion pressure than was MBF in patients with less severe disease. These 2 studies suggest a partial independence of MBF from perfusion pressure in experimental occlusion of the coronary arterial system as well as in human CAD. The observations may have therapeutic significance as well as lead to further study on the nature of flow inadequacy in CAD.
Consumption Coagulopathy as a Limiting Factor for the Total Prosthetic Heart CLIFFORD S. KWAN-GETT, MD; JUN KAWAI, PETERS, PhD; FRANCIS M. DONOVAN, Jr., KOLFF, MD, PhD, Salt Lake City, Utah
MD; JEFFREY PhD; WILLEM
L. J.
A compact spherical silastic heart was developed to produce an output of 10 liters/min with minimal hemoIytic effect. The prosthesis was implanted in 12 calves weighing from 68.0 kg-go.7 kg. Six calves survived longer than 24 hours (average 53.3 hours ; maximum 92 hours). Postoperatively the animals could drink, pass urine and stools, and they took an interest in their surroundings. The ventricles were driven by square wave pulses of compressed air at a constant rate of 100 beats/min. Stroke volumes varied automatically to keep atria1 pressures normal. The ventricles respond to Starling’s law of the heart without need for electronic control. Pulmonary arterial pressure wave forms showed wide variations without production of pulmonary hypertension. Aortic pressure wave forms did not appear to influence peripheral resistance. Plasma hemoglobin levels decreased from post-pump oxygenator levels of 34 mg/ 100 ml to 80 mg/lOO ml down to a minimum of 1.4% postoperatively. While animals appeared to be in good clinical condition, blood pressures, blood flow, peripheral resistance, Lee-White clotting time, arterial pH and arterial oxygenation remained within physiologic limits. However, there was a gradual fall in fibrinogen levels to 106 mg/lOO ml and platelet counts down to 10,000/mm3. Most experiments terminated soon after a series of convulsions. During the 4 hours before termination, Lee-White clotting times increased and levels of hematocrit, platelet count and fibrinogen concentration fell rapidly. At autopsy the prosthetic heart was always free of large thrombi, but multiple small organized thrombi were always found. The kidneys usually showed multiple small areas of infarction. These changes suggest the continuous consumption of coagulation factors, possibly by repeated formation on the prosthesis of clots shed as microemboli.
643
It is concluded that the rapid heart rates resulted in reduced dimensions of the RV outflow tract so that Qp decreased and R-L shunt and cyanosis increased. PAT should be added to the list of conditions that can precipitate cyanotic spells in some patients with T/F. Other supraventricular tachycardias may produce similar results.
Hemodynamic Correlates of Coronary Blood Flow and Myocardial Oxygen Consumption During Upright Exercise KAZUTO KITAMURA, MD; CHARLES R. JORGENSEN, MD; FREDARICK L. GOBEL, MD; HENRY TAYLOR, PhD;YANG WANG, MD, Minneapolis, Minnesota
This study was designed to evaluate hemodynamic indexes that are easily measurable, in some cases noninvasive, and that might have predictive value for myocardial oxygen consumption (MqO,) during various levels of upright exercise up to heavy exertion. Ten healthy male volunteers in their 20’s were studied. Catheters were placed in the ascending aorta and coronary sinus. Upright bicycle exercise was done at several levels to produce heart rates in the ranges of 100-110, 140-150 and 160-175 beats/min, and the following measurements were made: heart rate (HR) , blood pressure (BP), coronary blood flow (CBF) by the nitrous oxide saturation method, and A-V OZ difference. Modification of the CBF method was necessary to measure flows of the magnitude encountered. HR alone correlated well with CBF (r = 0.82) and MqO, (0.88). The correlation of HR x systolic BP with CBF (0.87) and MqO, (0.90) was even better. The tension-time index correlated less well with CBF and MqO, (0.83 and 0.77)) and the external work load was an even poorer correlate. It is concluded that heart rate can provide a useful standardization of cardiac stress for such purposes as exercise electrocardiography.
Perfusion Pressure and Myocardial Blood Flow SUZANNE McHENRY,
B. KNOEBEL, MD; LEON STEIN, MD, Indianapolis, Indiana
MD;
PAUL
L.
The concept that coronary blood flow (MFB) is perfusion pressure-dependent in patients with coronary artery disease (CAD) has had significance in consideration of therapy in this disease. To study the relation of MFB and perfusion pressure, 2 studies were undertaken. Shock was produced in 22 dogs by coronary embolization. The dogs were divided into 3 groups, Group 1 (untreated) ; Group 2 (isoproterenol [ISUI, 0.02-0.09 pg/kg per min) ; and Group 3 (norepinephrine [NE], 0.3-1.1 pg/kg per min). MBF, utilizing a coincidence counting-single bolus 84RbC1 technique, and mean, diastolic and systolic mean arterial pressures were measured 1 hour after embolization. NE and ISU resulted in significant (P
VOLUME
26,
DECEMBER
1970
A second study was performed in 60 patients with cinearteriographically proved CAD. MBF and arterial pressures were measured as in the dog study. There was no correlation through the third degree polynomial in analysis of variance between MBF and any of the arterial pressure changes with isoproterenol infusion (5 pg/min). The lack of correlation maintained for all degrees of severity of CAD as graded by percent of vessels remaining open. The MBF in patients with the most severe degree of coronary occlusive disease (45 or less of vessels remaining patent) was no more dependent on perfusion pressure than was MBF in patients with less severe disease. These 2 studies suggest a partial independence of MBF from perfusion pressure in experimental occlusion of the coronary arterial system as well as in human CAD. The observations may have therapeutic significance as well as lead to further study on the nature of flow inadequacy in CAD.
Consumption Coagulopathy as a Limiting Factor for the Total Prosthetic Heart CLIFFORD S. KWAN-GETT, MD; JUN KAWAI, PETERS, PhD; FRANCIS M. DONOVAN, Jr., KOLFF, MD, PhD, Salt Lake City, Utah
MD; JEFFREY PhD; WILLEM
L. J.
A compact spherical silastic heart was developed to produce an output of 10 liters/min with minimal hemoIytic effect. The prosthesis was implanted in 12 calves weighing from 68.0 kg-go.7 kg. Six calves survived longer than 24 hours (average 53.3 hours ; maximum 92 hours). Postoperatively the animals could drink, pass urine and stools, and they took an interest in their surroundings. The ventricles were driven by square wave pulses of compressed air at a constant rate of 100 beats/min. Stroke volumes varied automatically to keep atria1 pressures normal. The ventricles respond to Starling’s law of the heart without need for electronic control. Pulmonary arterial pressure wave forms showed wide variations without production of pulmonary hypertension. Aortic pressure wave forms did not appear to influence peripheral resistance. Plasma hemoglobin levels decreased from post-pump oxygenator levels of 34 mg/ 100 ml to 80 mg/lOO ml down to a minimum of 1.4% postoperatively. While animals appeared to be in good clinical condition, blood pressures, blood flow, peripheral resistance, Lee-White clotting time, arterial pH and arterial oxygenation remained within physiologic limits. However, there was a gradual fall in fibrinogen levels to 106 mg/lOO ml and platelet counts down to 10,000/mm3. Most experiments terminated soon after a series of convulsions. During the 4 hours before termination, Lee-White clotting times increased and levels of hematocrit, platelet count and fibrinogen concentration fell rapidly. At autopsy the prosthetic heart was always free of large thrombi, but multiple small organized thrombi were always found. The kidneys usually showed multiple small areas of infarction. These changes suggest the continuous consumption of coagulation factors, possibly by repeated formation on the prosthesis of clots shed as microemboli.
643