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Introduction: Marriage of the heart and the peripheral circulation
Progress
Cardiovascular VOL. XXIV,
in
Diseases
NO. 3
NOVEMBER/DECEMBER
Vasodilator Introduction:
1981
Symposium
Marriage of the Heart and the Peripheral Circulation Jay N. Cohn, M.D., GuestEditor
A
MAJOR CHANGE of emphasis in our approach to the evaluation and treatment of ventricular function abnormalities began about 10 years ago. This was the time when it began to become apparent that pump performance of the left ventricle was intimately related to the vasomotor state of the peripheral circulation and that its function could sometimes be as effectively improved by vasodilators as by inotropic drugs. In the past decade, therefore, the emphasis has changed from quantitation of that elusive muscle characteristic called “contractility” to assessment of the influence on cardiac function of changes in vascular resistance, impedance, and compliance. This new awareness of the importance of considering the heart and blood vessels as a functioning unit has increased our need for an understanding of the factors controlling the peripheral circulation and for methods to quantitate peripheral vascular phenomena that may influence cardiac performance. At long last, therefore, physiologic investigators interested in the heart are becoming interested in the periphery, and vice versa. This new era represents a remarkable change from the days when the diaphragm appeared to be an impenetrable barrier between cardiac and peripheral vascular research. The present symposium represents an attempt at a comprehensive review of advances in this whole vital area of cardiovascular investigation. Hopefully, it should provide an understanding of smooth muscle function and its neurohumoral
Progess
in Cardiovascular
Diseases,
Vol. XXIV,
No. 3 1November/Decamber),
control; of ways to quantitate the impedance the vasculature imposes on the heart; of how the left ventricle responds to changes in this impedance; of how the circulation may be altered in heart failure; of the various vasodilator drugs and how they may influence systemic and regional circulations; and of the hemodynamic and functional response to these drugs in patients with heart failure. It is a symposium that would not have been planned 10 years ago and one which therefore examines a rapidly evolving area of physiology, pharmacology, and therapeutics. Much obviously remains to be done. This still new approach to our understanding of pump function has already had a remarkable impact on the clinical management of heart disease. Old and new drugs with vasodilator effects are now being widely employed for a purpose different from which they were initially intended. Part of the enthusiasm for the use of these drugs is rooted in the present widespread application of hemodynamic monitoring in the management of severely ill cardiac patients. The dramatic acute hemodynamic effects of these drugs have impressed physicians with their usefulness in the treatment of pump failure. Furthermore, this exciting new area of therapeuFrom the Cardiovascular Division. University of Minnesota Medical School, Minneapolis, Minn. Reprint requests should be addressed to Jay N. Cohn, M.D.. Box 488. Mayo, University of Minnesota Hospitals, Minneapolis, Minn. 55455. 6 1981 by Grune & Stratton, Inc.
198 1
189
190
tics has blossomed more rapidly in the United States than in Europe, which has been the leader in many other recent areas of drug development. Many questions remain to be explored. Can quantitation of peripheral vascular phenomena by some clinically applicable method yield new insights into the role of various factors in influencing circulatory control in heart failure? Could such a measurement provide a useful means of monitoring cardiac patients and assessing their need for and response to vasodilator drugs? Could vasodilator therapy be individualized on the basis of the mechanism of the change in vasomotor tone? Do changes in peripheral vascular function play a role in the natural history of heart failure by setting into motion vicious cycles related to depressed performance of the left ventricle? Could vasodilator
JAY
N. COHN
therapy prevent the development of heart failure or influence the natural history of the disease? A large-scale study designed to examine the long-term efficacy of vasodilator drug therapy in patients with heart failure is now underway. Other studies to evaluate short-term efficacy of a variety of new drugs are also in progress. Until results of such studies are available, the use of these drugs for chronic management of heart failure must remain experimental. Nonetheless, this new attention to the interaction between the heart and periphery has stimulated a renaissance in the study of vascular phenomena. The end result of this interest will certainly be an expanded understanding of circulatory function and improved management of patients with heart disease.
Cardiovascular VOL. XXIV,
in
Diseases
NO. 3
NOVEMBER/DECEMBER
Vasodilator Introduction:
1981
Symposium
Marriage of the Heart and the Peripheral Circulation Jay N. Cohn, M.D., GuestEditor
A
MAJOR CHANGE of emphasis in our approach to the evaluation and treatment of ventricular function abnormalities began about 10 years ago. This was the time when it began to become apparent that pump performance of the left ventricle was intimately related to the vasomotor state of the peripheral circulation and that its function could sometimes be as effectively improved by vasodilators as by inotropic drugs. In the past decade, therefore, the emphasis has changed from quantitation of that elusive muscle characteristic called “contractility” to assessment of the influence on cardiac function of changes in vascular resistance, impedance, and compliance. This new awareness of the importance of considering the heart and blood vessels as a functioning unit has increased our need for an understanding of the factors controlling the peripheral circulation and for methods to quantitate peripheral vascular phenomena that may influence cardiac performance. At long last, therefore, physiologic investigators interested in the heart are becoming interested in the periphery, and vice versa. This new era represents a remarkable change from the days when the diaphragm appeared to be an impenetrable barrier between cardiac and peripheral vascular research. The present symposium represents an attempt at a comprehensive review of advances in this whole vital area of cardiovascular investigation. Hopefully, it should provide an understanding of smooth muscle function and its neurohumoral
Progess
in Cardiovascular
Diseases,
Vol. XXIV,
No. 3 1November/Decamber),
control; of ways to quantitate the impedance the vasculature imposes on the heart; of how the left ventricle responds to changes in this impedance; of how the circulation may be altered in heart failure; of the various vasodilator drugs and how they may influence systemic and regional circulations; and of the hemodynamic and functional response to these drugs in patients with heart failure. It is a symposium that would not have been planned 10 years ago and one which therefore examines a rapidly evolving area of physiology, pharmacology, and therapeutics. Much obviously remains to be done. This still new approach to our understanding of pump function has already had a remarkable impact on the clinical management of heart disease. Old and new drugs with vasodilator effects are now being widely employed for a purpose different from which they were initially intended. Part of the enthusiasm for the use of these drugs is rooted in the present widespread application of hemodynamic monitoring in the management of severely ill cardiac patients. The dramatic acute hemodynamic effects of these drugs have impressed physicians with their usefulness in the treatment of pump failure. Furthermore, this exciting new area of therapeuFrom the Cardiovascular Division. University of Minnesota Medical School, Minneapolis, Minn. Reprint requests should be addressed to Jay N. Cohn, M.D.. Box 488. Mayo, University of Minnesota Hospitals, Minneapolis, Minn. 55455. 6 1981 by Grune & Stratton, Inc.
198 1
189
190
tics has blossomed more rapidly in the United States than in Europe, which has been the leader in many other recent areas of drug development. Many questions remain to be explored. Can quantitation of peripheral vascular phenomena by some clinically applicable method yield new insights into the role of various factors in influencing circulatory control in heart failure? Could such a measurement provide a useful means of monitoring cardiac patients and assessing their need for and response to vasodilator drugs? Could vasodilator therapy be individualized on the basis of the mechanism of the change in vasomotor tone? Do changes in peripheral vascular function play a role in the natural history of heart failure by setting into motion vicious cycles related to depressed performance of the left ventricle? Could vasodilator
JAY
N. COHN
therapy prevent the development of heart failure or influence the natural history of the disease? A large-scale study designed to examine the long-term efficacy of vasodilator drug therapy in patients with heart failure is now underway. Other studies to evaluate short-term efficacy of a variety of new drugs are also in progress. Until results of such studies are available, the use of these drugs for chronic management of heart failure must remain experimental. Nonetheless, this new attention to the interaction between the heart and periphery has stimulated a renaissance in the study of vascular phenomena. The end result of this interest will certainly be an expanded understanding of circulatory function and improved management of patients with heart disease.